HK40034215B

HK40034215B - Method and system for additive manufacturing of peelable sacrificial structure

Info

Publication number: HK40034215B
Application number: HK62021023738.9A
Authority: HK
Inventors: 玛雅·伦巴克; 爱德华多·纳帕丁斯基; 贾维徐·美达
Original assignee: 斯特拉塔西斯公司
Priority date: 2017-12-28
Filing date: 2018-11-27
Publication date: 2023-12-01

Description

Method and system for additive manufacturing of strippable sacrificial structures

Related application

The present application claims the benefit of U.S. provisional patent application No. 62/611,064 filed on 12/28 at 2017, the contents of which are incorporated herein by reference in their entirety.

Technical field and background art

In some embodiments of the invention, the invention relates to Additive Manufacturing (AM), and more particularly, but not exclusively, to a method and system of additive manufacturing of peelable sacrificial structures.

Additive Manufacturing (AM) is a technique by which structures of arbitrary shape can be manufactured directly from computer data by an additive forming step. The basic operation of any additive manufacturing system involves slicing a three-dimensional computer model into thin sections, converting the results into two-dimensional positional data, and then providing the data to a control device that manufactures a three-dimensional structure in a hierarchical manner.

Additive manufacturing requires many different manufacturing methods including three-dimensional printing, such as three-dimensional inkjet printing, electron beam melting, photo-curing forming, selective laser sintering, stacked body manufacturing, fused deposition forming, and the like.

Three-dimensional (3D) printing processes, such as three-dimensional inkjet printing, are performed by layer-by-layer inkjet deposition of build material. Thus, a build material is dispensed from a dispensing head having a set of nozzles to deposit layers on a support structure. Depending on the construction material, the layer may be cured (cured) or cured (cured) using a suitable device.

Various three-dimensional printing techniques exist and are disclosed in, for example, U.S. Pat. nos. 6,259,962, 6,569,373, 6,658,314, 6,850,334, 6,863,859, 7,183,335, 7,209,797, 7,225,045, 7,300,619, and 7,500,846, and U.S. patent application publication No. 20130073068, all of which are filed by the same assignee and are hereby incorporated by reference in their entirety.

The build material of a typical additive manufacturing process includes a modeling material that is deposited to produce the desired object, and a support material that provides temporary support to specific areas of the object during the build process and ensures proper vertical placement of subsequent object layers. For example, where the object includes overhanging features or shapes, such as curved geometries, negative angles, voids, etc., adjacent support structures are typically used to construct the object, which support structures are used during printing and then removed to reveal the final shape of the manufactured object.

Known methods of removing the support material include water jet impingement, chemical methods such as dissolution in a solvent, often in combination with heat treatment. For example, for a water-soluble support material, the object being fabricated, including its support structure, is immersed in water capable of dissolving the support material.

Support materials for additive manufacturing are described, for example, in U.S. Pat. nos. 6,228,923, 7,255,825, 7,479,510, 7,183,335, and 6,569,373, all of which are owned by the assignee hereof and incorporated by reference in their entirety.

U.S. patent No. 8,865,047, assigned to the present assignee, discloses a method of constructing a support structure that includes a strip that intersects a layer in a volume of space designed to be empty in a three-dimensional object. The support structure is removed from the volume by applying a lifting force to the strip.

Disclosure of Invention

According to an aspect of some embodiments of the present invention, there is provided an additive manufacturing method of a three-dimensional object. The method comprises the following steps: sequentially dispensing and curing a plurality of layers, the plurality of layers comprising: (i) A stack of layers comprising a modeling material arranged in a configuration pattern corresponding to the shape of the object; (ii) A stack of layers comprising a flexible material and forming a sacrificial structure; and (iii) a stack of layers comprising a soft material having a modulus of elasticity less than a modulus of elasticity of the soft material and forming an intermediate structure between the object and the sacrificial structure; and applying a peel force to the sacrificial structure (e.g., in a dry environment) to separate the sacrificial structure from the object.

According to another aspect of the invention, a system for manufacturing a three-dimensional object by additive manufacturing is provided. The system comprises: a plurality of dispensing heads, such as at least a first dispensing head, configured to dispense a modeling material; a second dispensing head configured to dispense a flexible material; and a third dispensing head configured to dispense a soft material having a modulus of elasticity less than the soft material; a curing system configured to cure each of the plurality of materials; and a computer controller having a circuit configured for operating the plurality of dispensing heads and the curing system to sequentially dispense and cure the plurality of layers as described above, and optionally and preferably as described and exemplified in further detail below.

According to another aspect of the present invention, a three-dimensional inkjet color printer suitable for use in home and office environments is provided. In some exemplary embodiments, the applicability of home and office use is based on the fact that printer use can readily form at least a portion of the sacrificial structure from the model structure, i.e., material that is separated from the three-dimensional object being printed (e.g., by manually peeling the sacrificial structure off the object). Optionally, the flexible material forming at least a portion of the peelable sacrificial structure is an elastomeric material. The separation may be performed at the end of the printing process without the need for dedicated equipment or solvents. In this way, the sacrificial structures can be removed quickly and neatly, and little waste is generated. In some exemplary embodiments, the additional portion of the sacrificial structure may be formed of a soft material, such as, but not limited to, a material that is soluble in water or solvents. Alternatively, a soft material is applied between the modeling material forming the object and the flexible material of the sacrificial structure (i.e., the intermediate structure), and may be attached to and peeled off with the flexible material that is peeled off. Alternatively, once the flexible material is removed, the soft material or residues of soft material of the intermediate structure on the object can be easily removed by rubbing or immersing the object in water.

In exemplary embodiments, the applicability of home and office use is also based on a compact size of a three-dimensional inkjet color printing system for printing full color objects, including up to three printheads, e.g., each head including two linear nozzle arrays. Each nozzle array is dedicated to printing a different material, for example, the system deposits five different colors of modeling material and a support material. In order to provide the sacrificial structure of the present invention using a flexible material that can be used in place of one of the colored modeling materials, without adding another printhead, and thus compromising the compact size of the printing system, the compact system can deposit four different colored modeling materials, a flexible material, and a support material. Optionally, a flexible material having a color similar to the color of the color model material it replaces is selected, optionally and preferably, a black model material is selected. In some example embodiments, the color of the missing modeling material, e.g., black, is created by digitally combining the modeling material that provides the other colors for use by the printer, e.g., a combination of Cyan, magenta, and yellow (Cyan, magenta and Yellow, CMY).

The inventors have found that the mechanical properties of the object are not significantly affected when using a flexible material instead of one of the model materials in the object, for example when fine details are created in the object, or when using a flexible material to create a relatively small volume portion of the object. Thus, in addition to being used as a peelable material for sacrificial structures, black flexible materials may also be used, for example, to create fine details in the three-dimensional object being formed.

According to an aspect of some exemplary embodiments, there is provided a method of additive manufacturing of a three-dimensional object, comprising: sequentially dispensing and curing a plurality of layers, wherein the plurality of layers are formed of (i) a plurality of differently colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) A flexible material arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) a soft material arranged in a configuration pattern to provide separation between the model material and the sacrificial structure.

Optionally, the soft material has an elastic modulus smaller than an elastic modulus of the soft material.

Optionally, the plurality of different colored mold materials does not include a black mold material.

Optionally, the flexible material is black.

Optionally, a black portion of the object is formed based on: (i) Digitally mixing the plurality of differently colored modeling materials to produce a black color; (ii) an amount of black flexible material; or (iii) a combination of said (i) and said (ii).

Optionally, the flexible material is black.

According to an aspect of some exemplary embodiments, there is provided a computer software product comprising: a computer readable medium storing program instructions that, when read by a computer controller of an additive manufacturing system, cause the system to sequentially dispense and cure layers formed of: (i) A plurality of differently colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) A flexible material arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) a soft material arranged in a configuration pattern to provide separation between the model material and the sacrificial structure.

Optionally, the flexible material is black.

Optionally, the plurality of instructions includes a plurality of commands to form a black color in the object by: (i) digitally mixing a plurality of colored modeling materials; (ii) printing a quantity of black flexible material; or (iii) combining said (i) with said (ii).

According to an aspect of some exemplary embodiments, there is provided an Additive Manufacturing (AM) system for manufacturing a three-dimensional colored object, the system comprising: a building material supply apparatus configured to house a set of supply boxes, wherein the set of supply boxes comprises: a set of cartridges having different colored modeling materials; a case comprising a flexible material; and a case comprising a soft material having a modulus of elasticity less than a modulus of elasticity of the soft material; a plurality of nozzle arrays mounted in a plurality of dispensing heads configured to receive a plurality of materials from the build material supply apparatus; a curing system configured to cure the plurality of materials dispensed from the plurality of dispensing heads; and a computer controller having a circuit configured for operating the plurality of dispensing heads and the curing system to sequentially dispense and cure a plurality of layers comprising: (i) A plurality of different colored modeling materials arranged in a configuration pattern corresponding to the shape and color definition of the object; (ii) The flexible material being arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) the soft material is arranged in a configuration pattern to provide separation between the model material and the sacrificial structure.

Optionally, the flexible material is black.

Optionally, the plurality of dispensing heads are configured to operate by printing the following materials to print a black color in the object: (i) A digital mixture of a plurality of different colored modeling materials; (ii) an amount of black flexible material; or (iii) a combination of said (i) and said (ii).

According to an aspect of some exemplary embodiments, there is provided an additive manufacturing system for manufacturing a three-dimensional object, the system comprising: a building material supply apparatus configured to accommodate a maximum of six supply cartridges, wherein the plurality of supply cartridges is selected from a group comprising: a plurality of cartridges having different colored modeling materials; a plurality of cartridges having a flexible material; and a plurality of cartridges having a soft material, wherein a modulus of elasticity of the soft material is less than a modulus of elasticity of the soft material; a maximum of six nozzle arrays mounted in a plurality of dispensing heads configured to receive a plurality of materials from the build material supply apparatus; a curing system configured to cure the plurality of materials dispensed from the plurality of dispensing heads; and a computer controller having a circuit configured for operating the plurality of dispensing heads and the curing system to sequentially dispense and cure a plurality of layers comprising: (i) A plurality of differently colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) The flexible material being arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) the soft material arranged in a configuration pattern to provide separation between the model material and the sacrificial structure; wherein the plurality of differently colored mold materials does not include a black mold material.

According to an aspect of some exemplary embodiments, there is provided a system for manufacturing a three-dimensional object by additive manufacturing, the system comprising: a building material supply apparatus configured to accommodate a maximum of six supply cartridges, wherein the plurality of supply cartridges is selected from a group comprising: a plurality of cartridges having a plurality of different colored modeling materials; a plurality of cartridges having a flexible material; and a plurality of cartridges having soft materials, wherein a modulus of elasticity of the soft materials is less than a modulus of elasticity of the soft materials, and wherein the plurality of differently colored model materials include white, cyan, magenta, and yellow; a maximum of three dispensing heads configured to receive a plurality of materials from the build material supply apparatus; a curing system configured to cure each of the plurality of materials; and a computer controller having a circuit configured for operating the plurality of dispensing heads and the curing system to sequentially dispense and cure a plurality of layers comprising: (i) The plurality of different colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) The flexible material being arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) the soft material arranged in a configuration pattern to provide separation between the model material and the sacrificial structure; wherein at least a portion of the three dispensing heads are configured to operate with digitally mixed cyan, magenta, and yellow to produce a black color in the object.

Optionally, the flexible material is black, and wherein the flexible material is applied to form at least a portion of the object defined as black.

Optionally, the flexible material is black, and wherein the flexible material is included in a digital mix of the differently colored model materials to produce the black in the object.

Alternatively, if the volume of the black portion is greater than a defined threshold, a black portion of the object is formed based on a digital mix of the different colored model materials.

Optionally, if the volume of the black portion is less than the defined threshold, the black portion is made of the flexible material.

Optionally, the soft material is arranged in a configuration pattern to form a plurality of spaces in the sacrificial structure.

Optionally, the plurality of spaces are formed on a plurality of symmetrical planes with respect to the object.

Optionally, the soft material is configured to fill a plurality of holes defined by a geometry of the object.

Optionally, the soft material is configured to contain a plurality of fine features that are prone to fracture when a tensile or peeling force is applied in the vicinity of the plurality of fine features.

Optionally, the soft material is formed from a gel that is water soluble.

Optionally, a thickness of the separation between the modeling material and the sacrificial structure provided by the soft material is 100 microns to 300 microns.

Optionally, a minimum thickness of the sacrificial structure is from about 500 microns to about 3 millimeters.

Optionally, at least a portion of the mold material has a flexural modulus of 2000 megapascals to 4000 megapascals.

Optionally, the mold material comprises at least one additional non-curable material, wherein the non-curable material is selected from the group comprising: a colorant, an initiator, a dispersant, a surfactant, a stabilizer and an inhibitor.

Optionally, the sacrificial structure is characterized by: the sacrificial structure has a tear resistance after curing of at least 4 kilonewtons per meter when measured according to international standard ASTM D-624 after curing.

Optionally, the sacrificial structure is characterized by: the sacrificial structure has a tear resistance after curing of from about 4 kilonewtons per meter to about 8 kilonewtons per meter when measured according to international standard ASTM D-624.

Optionally, the sacrificial layer is configured to be peeled off, and wherein a magnitude of the peeling force is from about 1 newton to about 20 newtons.

Optionally, the sacrificial layer is configured such that the peel force of 5 newtons results in a bending strain of at least 0.02.

Optionally, the flexible material is a formulation comprising a plurality of silica particles.

Optionally, the formulation is characterized by: a tear resistance upon hardening is at least 0.5 kilonewtons per meter higher than a cured formulation having the same flexible material but without the plurality of silica particles.

Optionally, the plurality of silica particles has an average particle size of less than 1 micron

Optionally, at least a portion of the plurality of silica particles comprises a hydrophilic surface.

Optionally, at least a portion of the plurality of silica particles comprises a hydrophobic surface.

Optionally, at least a portion of the plurality of silica particles comprises a plurality of functionalized silica particles.

Optionally, at least a portion of the plurality of silica particles are functionalized with a plurality of curable functional groups.

Optionally, the plurality of curable functional groups comprises a plurality of (meth) acrylate groups.

Optionally, a content of the plurality of silica particles in the formulation ranges from about 1 to about 20 wt%, from about 1 to about 15 wt%, or from about 1 to about 10 wt% of the total weight of the formulation.

Optionally, a weight ratio of the flexible material to the plurality of silica particles ranges from about 30:1 to about 4:1.

optionally, the flexible material is present in an amount of at least 40% or at most 50% of the total weight of the formulation.

Optionally, the flexible material comprises one or more of the following materials: a monofunctional elastomer monomer, a monofunctional elastomer oligomer, a multifunctional elastomer monomer, and a multifunctional elastomer oligomer.

Optionally, the formulation includes an additional curable material.

Optionally, the formulation includes an elastomeric monofunctional curable material, an elastomeric polyfunctional curable material, and an additional monofunctional curable material.

Alternatively, a concentration of the elastomeric monofunctional material ranges from about 10% to about 30% by weight.

Alternatively, a concentration of the elastomeric monofunctional curable material ranges from about 50% to about 70% by weight.

Optionally, a concentration of the elastomeric multifunctional curable material ranges from about 10% to about 20% by weight.

Optionally, a concentration of the monofunctional curable material ranges from about 20% to about 30% by weight.

Alternatively, a concentration of the elastomeric monofunctional curable material ranges from about 30% to about 50% by weight.

Optionally, a concentration of the elastomeric multifunctional curable material ranges from about 10% to about 30% by weight.

Optionally, the flexible material is an ultraviolet curable elastomeric material.

The flexible material is an acrylic elastomer.

Unless defined otherwise herein, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification and its definitions will control. In addition, the materials, methods, and examples are illustrative only and not intended to be necessarily limiting.

Implementation of the methods and/or systems of embodiments of the present invention may involve performing or completing selected tasks manually, automatically, or a combination thereof. Furthermore, the actual instrumentation and equipment of the embodiments of the method and/or system of the present invention may utilize an operating system to implement several selected tasks through hardware, software, firmware, or a combination thereof.

For example, hardware for performing selected tasks according to embodiments of the invention could be implemented as a chip or a circuit. As software, selected tasks according to embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to exemplary embodiments of the methods and/or systems described herein are performed by a data processor, such as a computing platform for executing instructions.

Optionally, the data processor comprises a volatile memory for storing instructions and/or data and/or a non-volatile memory for storing instructions and/or data, such as a magnetic hard disk and/or removable media. Optionally, a network connection is also provided. A display and/or a user input device such as a keyboard or mouse are also optionally provided.

Drawings

Some embodiments of the invention are described herein, by way of example only, with reference to the accompanying drawings and figures. Referring now specifically to the drawings in detail, it is emphasized that the details shown are by way of example and are for purposes of illustrative discussion of embodiments of the invention. In this regard, it is apparent to those skilled in the art how embodiments of the present invention may be practiced in conjunction with the description of the drawings.

In the drawings:

FIGS. 1A-1D are schematic illustrations of additive manufacturing systems according to some embodiments of the present invention;

FIGS. 2A-2C are schematic diagrams of printheads according to some embodiments of the present invention;

FIGS. 3A and 3B are schematic diagrams illustrating coordinate transformations according to some embodiments of the present invention;

FIG. 4 is a schematic diagram of an additive manufacturing full color system according to some embodiments of the invention;

FIGS. 5A and 5B are exemplary top and perspective views of a print block of an additive manufacturing system according to some embodiments of the present invention;

FIG. 6 is a flowchart of a method according to various exemplary embodiments of the invention;

FIG. 7A is a simplified flowchart of an exemplary method of supporting a printed object using a combination of support materials, according to some embodiments of the present invention;

FIG. 7B is a simplified flowchart of an exemplary method of color printing using an additive manufacturing system, according to some embodiments of the present invention;

FIGS. 8A and 8B are schematic illustrations of two different configurations for printing an object using a peelable flexible material and an intermediate flexible structure, according to some embodiments of the invention;

FIGS. 9A and 9B are schematic illustrations of two different configurations for printing an object comprising a large support volume, the object being surrounded by a peelable flexible material and an intermediate flexible structure, according to some embodiments of the invention;

FIGS. 10A and 10B are schematic illustrations of an object having a closed loop geometry printed with a peelable flexible material and an intermediate flexible structure according to some embodiments of the invention;

FIGS. 11A, 11B and 11C are schematic illustrations of three different configurations for printing an object including an aperture, the object being surrounded by a peelable flexible material and an intermediate flexible structure, according to some embodiments of the invention;

FIGS. 12A, 12B, and 12C are schematic illustrations of three different configurations for printing an object including a high aspect ratio slot, the object being surrounded by a peelable flexible material and an intermediate flexible structure, according to some embodiments of the invention;

FIGS. 13A, 13B, and 13C are schematic illustrations of three different configurations for printing an object including a fine feature having surrounding flexible material forming a sacrificial structure, according to some embodiments of the invention;

FIGS. 14A, 14B, 14C and 14D illustrate an exemplary process of stripping a black elastomeric sacrificial structure from a color model according to some embodiments of the invention;

fig. 15 is a chart showing Shore a (Shore a) values for various black samples printed in different model/flexible material combinations, according to some embodiments of the present invention; and

fig. 16 is a graph showing viscosity values of various black samples printed in different model/flexible material combinations, according to some embodiments of the present invention.

Detailed Description

In some embodiments of the invention, the invention relates to Additive Manufacturing (AM), and more particularly, but not exclusively, to methods and systems for additive manufacturing of a strippable sacrificial structure for a full-color three-dimensional object formed by an additive manufacturing apparatus.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and to the arrangements and/or the methods of the components set forth in the following description and/or illustrated in the drawings or examples. The invention is capable of other embodiments or of being practiced or of being carried out in various ways.

The method and system of the present embodiment manufacture a three-dimensional object based on computer object data in a layered manner by forming a plurality of layers in a configuration pattern corresponding to the shape of the object. The Computer object data may be in any known format including, but not limited to, standard tessellation language (Standard Tessellation Language, STL) or stereolithography profile (StereoLithography Contour, SLC) format, virtual reality modeling language (Virtual Reality Modeling Language, VRML), additive manufacturing file (Additive Manufacturing File, AMF) format, drawing exchange format (Drawing Exchange Format, DXF), polygon archive format (Polygon File Format, PLY), or any other suitable Computer-Aided Design (CAD) format.

As used herein, the term "object" refers to an entire object or a portion thereof. The term "object" describes a final product of additive manufacturing. If a support material has been used as part of a construction material, this term refers to the product obtained by the method described herein after removal of the support material. Thus, an "object" consists essentially of hardened (e.g., cured) model material (at least 95 weight percent (wt%)).

Each layer is formed by an additive manufacturing apparatus that scans and patterns a two-dimensional surface. Upon scanning, the device accesses a plurality of target locations on a two-dimensional layer or surface and, for each target location or group of target locations, determines whether the target location or group of target locations is to be occupied by build material, and to which type of build material is to be delivered. The determination is made from a computer image of the surface.

The term digital mixing refers to the distribution of two or more materials, optionally of different colors or characteristics, in an interleaved manner at the microscopic scale or voxel level. Such a digital mix may exhibit a new color or characteristic that is different from the color or characteristic of the individual materials when viewed macroscopically.

Each voxel or voxel block will produce a different model material, e.g. the new color of the digital blend area is the result of spatial combination of several different model materials at the voxel level.

The term "at the voxel level" as used herein in the context of different materials and/or colors includes differences between blocks of voxels, as well as differences between individual voxels or groups of several voxels.

In some embodiments of the invention, additive manufacturing comprises three-dimensional printing, more preferably three-dimensional inkjet printing. In these embodiments, a build material is dispensed from a dispensing head having a set of nozzles to deposit build material hierarchically on a support structure. Thus, the additive manufacturing apparatus distributes the build material in the target locations to be occupied and leaves the other target locations empty.

An apparatus according to some embodiments of the invention includes a plurality of dispensing heads, each dispensing head configured to dispense one or more different build materials. Thus, different build materials may occupy different target locations. The types of construction materials can be divided into two main categories: a modeling material and a support material. The support material serves as a support matrix or structure to support the object or object component during the manufacturing process and/or other purposes (e.g., providing a hollow or porous object). The support structure may additionally comprise model material elements, for example for obtaining further support strength.

The modeling material is typically a composition formulated for additive manufacturing, and it is optionally and preferably capable of forming a three-dimensional object alone, i.e., without mixing or combining with any other substance.

The final three-dimensional object is made of a mold material or a combination of two or more mold materials, or a combination of a mold and a support material, or modifications thereof, e.g., after curing (curing), such as but not limited to curing (curing). All of these operations are well known to those skilled in the art of solid freeform fabrication.

During the same pass of the printheads of the additive manufacturing apparatus, material(s) are optionally and preferably deposited in layers. The material(s) within the layer and the combination(s) of materials may be selected according to the desired characteristics of the object being printed.

According to some exemplary embodiments of the present disclosure, an additive manufacturing apparatus, such as a three-dimensional inkjet printer, may print three-dimensional objects having a plurality of different colors, and may also print a sacrificial structure that can be simply separated from the three-dimensional objects in a manner suitable for home and office use. Existing systems typically use materials that are not easily separated from the three-dimensional object to form the sacrificial structure. They are often messy and require special equipment to remove the sacrificial structures from the printed object. These known methods are inconvenient for a home or office environment. The present inventors have found that a clean and easily removable sacrificial structure is required and have invented a technique that allows such easy removal. The material forming the sacrificial structure may be of elastomeric quality so that it is suitable for being peeled from the mold material forming the object.

A three-dimensional inkjet printer for home and office use is optional and preferably designed to be compact and easy to use. In some exemplary embodiments, a compact printer or printing system according to some exemplary embodiments includes at most three inkjet printheads, e.g., each inkjet printhead includes two linear nozzle arrays, where each nozzle array may be dedicated to printing different materials, such that, for example, the system is capable of depositing five different colors of model material and support material, typically cyan, magenta, yellow, black, white, and a support material.

To add a flexible material to form the peelable sacrificial structures or at least a portion thereof without affecting the compactness of the printing system, for example, without adding additional printheads, one of the colored modeling materials may be replaced with a flexible material having a color similar to the color of the color modeling material being replaced to form the sacrificial structures. Thus, a compact system can deposit four different colors of modeling material, a flexible material, and a support material.

Although flexible materials may be used in place of any one or more of the colored modeling materials in accordance with embodiments of the present invention, the inventors have found that it is advantageous to use a black flexible material instead of a black modeling material for the following reasons: (1) Black is not widely used as a model material when printing a full-color object; (2) Three-dimensional digital colors typically do not require a large number of black "voxels" to obtain the desired color effect; (3) The large black areas of an object requiring black model material may be created by depositing one of the following materials: a separate black flexible material; a digital combination of colored model materials that produce a black color, such as Cyan, magenta, and yellow (Cyan, magenta and Yellow, CMY); or a digital combination of black flexible material and CMY model material; (4) The fine details and small volume of the black color of the object, i.e. when small amounts are required, can be formed using a flexible material of black color without significantly affecting the mechanical properties of the object.

Those skilled in the art will readily appreciate that while this embodiment may be particularly suited for a compact full color system including three dual linear channel printheads (or six single linear channel printheads) for printing model materials in five primary colors and one support material (CMYKW-S), the present invention is also applicable to full color systems including additional or alternative color model materials, such as clear, orange, violet, light cyan, light magenta, which would require more than three dual channel (or six single channel) printheads to create a usable palette (color palette). In some particular embodiments of the present invention, a full-color printing system includes: at least four channels (i.e., nozzle arrays, such as a linear nozzle array) for ejecting modeling material of primary colors; at least one channel for injecting a soft material; and at least one channel for injecting a flexible material, preferably a black flexible material.

A representative and non-limiting example of a system 110 suitable for additive manufacturing of an object 112 according to some embodiments of the invention is shown in fig. 1A. The system 110 includes an additive manufacturing apparatus 114 having a dispensing unit 16, the dispensing unit 16 including a plurality of dispensing heads. As shown in fig. 2A-2C, each head preferably includes an array of one or more nozzles 122 through which a liquid build material 124 is dispensed.

Preferably, but not necessarily, the device 114 is a three-dimensional printing device, in which case the dispensing head is a printhead, and the build material is dispensed by inkjet technology. This need not necessarily be the case, as for some applications the additive manufacturing apparatus may not necessarily employ three-dimensional printing techniques. Representative examples of additive manufacturing apparatuses contemplated in accordance with various exemplary embodiments of the present invention include, but are not limited to, fused deposition modeling (fused deposition modeling) apparatuses and fused material deposition (fused material deposition) apparatuses.

Each dispensing head is optionally and preferably fed via a building material reservoir, which may optionally include a temperature controller (e.g., a temperature sensor and/or a heating device), and a level sensor. To dispense build material, such as in piezoelectric inkjet printing technology, a voltage signal is applied to a dispense head to selectively deposit droplets of material through a dispense head nozzle. The dispensing rate of each spray head depends on the number of nozzles, the type of nozzle, and the rate (frequency) of the applied voltage signal. Such dispensing heads are well known to those skilled in the art of solid freeform fabrication.

In the representative example of fig. 1A, four dispensing heads 16a, 16b, 16c, and 16d are shown. Each of the heads 16a, 16b, 16c and 16d has an array of nozzles. In this example, heads 16a and 16b may be designated for model material(s), and heads 16c and 16d may be designated for support material. Thus, head 16a may dispense a first modeling material, head 16b may dispense a second modeling material, and both heads 16c and 16d may dispense support material. In an alternative embodiment, each of the heads 16a, 16b, and 16c may dispense one or more different modeling materials. In alternative embodiments, heads 16c and 16d may be combined, for example, in a single head having two nozzle arrays for depositing the support material. In alternative embodiments, both heads 16a and 16b may dispense the same modeling material, or may be combined in a single head having two nozzle arrays for depositing one or two different modeling materials. In another alternative embodiment, the dispensing unit 16 includes only heads 16a (for dispensing a modeling material) and 16c (for dispensing a support material), and the system 110 does not include any other dispensing heads other than heads 16a and 16 c.

It should be understood, however, that this is not intended to limit the scope of the present invention, and the number of modeling material deposition heads (modeling heads), the number of support material deposition heads (support heads), and the number of nozzle arrays in any one or more of the heads may be different.

In a preferred embodiment, there are M model heads, each model head having an array of M p nozzles; and S support heads, each having an array of S q nozzles, such that m×m×p=s×s×q. Each of the mxm model array and the sxs support array may be fabricated as a single physical unit that may be assembled and disassembled from groups of arrays. In this embodiment, each such array optionally and preferably includes its own temperature controller and a level sensor, and receives one or more voltages for an individual control of its operation.

The apparatus 114 may also include a curing system 324, such as a hardening device 324, which may include any device configured to emit light, heat, or the like, that may cure, and optionally and preferably harden, the deposited material. For example, curing system 324 may include one or more radiation sources, which may be, for example, an ultraviolet, visible, or infrared lamp, or other electromagnetic radiation source or electron beam source, depending on the modeling material used. In some embodiments of the present invention, the curing system 324 is used to cure (cure) or cure (solidifing) the modeling material. In some embodiments of the present invention, the curing system 324 is used to cure (cure) or cure (solidifing) the modeling material and the support material.

The dispensing head and the radiation source are preferably mounted on a frame or block 128, which frame or block 128 is preferably operable to reciprocate on a tray 360 as a work surface. In some embodiments of the invention, the radiation sources are mounted in the block such that they follow the dispensing head to at least partially cure (e.g., cure) the material just dispensed by the dispensing head. The tray 360 is placed horizontally. According to common practice, the X-Y-Z Cartesian coordinate system (Cartesian coordinate system) is selected such that the X-Y plane is parallel to the tray 360. The tray 360 is preferably configured to move vertically (along the Z-direction), generally downward. In various exemplary embodiments of the invention, the apparatus 114 further includes one or more leveling devices (leveling devices) 132, such as a roller 326. Leveling device 132 is used to straighten, level and/or establish a thickness of the newly formed layer prior to forming a continuous layer thereon. The leveling device 326 preferably includes a waste collection device 136 for collecting excess material generated during leveling. The waste collection device 136 may include any mechanism for delivering material to a waste bin or waste canister.

In use, the plurality of dispensing heads 16 of a unit move in a scanning direction, referred to herein as the X-direction, and selectively dispense build material in a predetermined configuration during passage of the plurality of dispensing heads 16 of the unit through the tray 360. The build material typically includes one or more support materials and one or more modeling materials. After the multiple dispense heads 16 of the unit pass, the modeling material(s) are cured by the radiation source 126. In the reverse pass of the plurality of heads, returning to the start of the just deposited layer, an additional dispensing of building material may be performed according to a predetermined configuration. In the forward and/or reverse pass of the plurality of dispensing heads, the layer thus formed may be straightened by a leveling device 326, which preferably follows the path of the plurality of dispensing heads as they move forward and/or in reverse. Once the multiple dispense heads return to their starting points in the X direction, they can be moved in an indexing direction (referred to herein as the Y direction) to another position and continue to build the same layer by reciprocating in the X direction.

Alternatively, multiple dispensing heads may be moved in the Y direction between forward and reverse movements or after more than one forward-reverse movement. A series of scans performed by multiple dispense heads to complete a single layer is referred to herein as a single scan cycle.

Once the layer is completed, the tray 360 is lowered in the Z direction to a predetermined Z level, depending on the desired thickness of the layer to be subsequently printed. This process is repeated to form the three-dimensional object 112 in a layered fashion.

In another embodiment, the tray 360 may be movable in the Z direction within the layer between the forward and reverse paths of the multiple dispensing heads 16 of the unit. This Z displacement is performed in order to bring the leveling device into contact with the surface in one direction and to prevent contact in the other direction.

The system 110 optionally and preferably includes a build material supply system or apparatus 330 that includes a plurality of build material containers or cartridges and supplies a plurality of build materials to the printheads of the manufacturing apparatus 114.

A computerized controller, such as control unit 152, controls manufacturing equipment 114 and optionally and preferably also supply system 330. The controller 152 generally includes an electronic circuit configured to perform controlling a plurality of operations. The controller 152 is preferably in communication with a data processor 154, the data processor 154 transmitting digital data relating to manufacturing instructions based on computer object data, such as a CAD configuration represented on a computer readable medium in any of the aforementioned formats, such as STL. Typically, the controller 152 controls the voltage applied to each dispense head or nozzle array, and the temperature of the build material in the corresponding print head.

Once the manufacturing data is loaded into the controller 152, it can be run without user intervention. In some embodiments, the controller 152 receives additional input from an operator, for example, using the data processor 154 or using a user interface 116 in communication with the unit 152. The user interface 116 may be of any type known in the art such as, but not limited to, a keyboard, a touch screen, etc. For example, the controller 152 may receive one or more build material types and/or properties as additional inputs, such as, but not limited to, color, distortion of characteristics and/or transition temperature, viscosity, electrical properties, magnetic properties. Other attributes and attribute groups are also contemplated.

Fig. 1B-1D illustrate another representative and non-limiting example of a system 10 suitable for additive manufacturing of an object, according to some embodiments of the present invention. Fig. 1B-1D show a top view (fig. 1B), a side view (fig. 1C), and an isometric view (fig. 1D), respectively, of system 10.

In this embodiment, the system 10 includes a tray 12 and a plurality of dispensing heads 16, optionally and preferably inkjet printheads, each having a plurality of separate nozzles. The tray 12 may be disk-shaped or may be annular. Non-circular shapes are also contemplated as long as they can rotate about a vertical axis.

Optionally and preferably, the tray 12 and head 16 are mounted to allow relative rotational movement between the tray 12 and head 16. This can be achieved by: (i) The tray 12 is configured to rotate about a vertical axis 14 relative to the head 16; (ii) The head 16 is configured to rotate about the vertical axis 14 relative to the tray 12; or (iii) the tray 12 and head 16 are configured to rotate about the vertical axis 14 but at different rotational speeds (e.g., counter-rotation). While the following embodiments emphasize configuration (i) in particular, wherein the tray is a rotating tray configured to rotate about vertical axis 14 relative to head 16, it should be understood that configurations (ii) and (iii) are also contemplated herein. Any of the embodiments described herein may be adapted for use with any of configurations (ii) and (iii), and one of ordinary skill in the art will know how to make such adaptations given the details described herein.

In the following description, a direction parallel to the tray 12 and pointing outward from the shaft 14 is referred to as a radial direction r, and a direction parallel to the tray 12 and perpendicular to the radial direction r is referred to herein as an azimuthal directionAnd a direction perpendicular to the tray 12 is referred to herein as a vertical direction z.

The term "radial position" as used herein refers to a position on or above the tray 12 at a particular distance from the shaft 14. When used in connection with a printhead, the term refers to a position of the printhead at a particular distance from the axis 14. When the term is used in connection with a point on the tray 12, the term corresponds to any point belonging to a locus of points, the locus being a circle having a radius at a specific distance from the axis 14 and being centered on the axis 14.

The term "azimuth position" as used herein refers to a position on or above the tray 12 at a particular azimuth angle relative to a predetermined reference point. Thus, a radial position refers to any point belonging to a trajectory of points, said trajectory being a straight line forming a specific azimuth angle with respect to said reference point.

The term "vertical position" as used herein refers to a position on a plane intersecting the vertical axis 14 at a particular point.

The tray 12 serves as a horizontal surface for three-dimensional printing. Typically, but not necessarily, the working area on which the object or objects are printed is less than the total area of the tray 12. In some embodiments of the invention, the working area is annular. The working area is shown at 26. In some embodiments of the invention, the tray 12 rotates continuously in the same direction throughout the formation of the object, and in some embodiments of the invention, the tray reverses the direction of rotation (e.g., in an oscillating manner) at least once during formation of the object. The tray 12 is optional and preferably detachable. The removal tray 12 may be used to service the system 10 or to replace the tray before printing a new object if desired. In some embodiments of the invention, the system 10 has one or more different replacement trays (e.g., a kit of replacement trays), where two or more trays are designated for different types of objects (e.g., different weights), different modes of operation (e.g., different rotational speeds), etc. The replacement of the tray 12 may be manual or automatic, as desired. When automatic replacement is employed, the system 10 includes a tray replacement device 36 configured to remove the tray 12 from its position under the head 16 and replace it with a replacement tray (not shown). In the representative illustration of fig. 1B, the pallet changing apparatus 36 of fig. 1B is shown as a drive 38 having a movable arm 40 configured to pull the pallet 12, although other types of pallet changing apparatus are contemplated.

In some embodiments, system 10 includes a tray support member 30 positioned below head 16 such that tray 12 is between tray support member 30 and head 16. The tray support member 30 may be used to prevent or reduce vibration of the tray 12 that may occur when the head 16 is operated. In a configuration in which printhead 16 rotates about axis 14, tray support member 30 preferably also rotates such that tray support member 30 is always directly under head 16 (tray 12 between head 16 and tray 12).

Tray 12 and/or printheads 16 are optionally and preferably configured to move along a vertical direction z parallel to vertical axis 14 to vary the vertical distance between tray 12 and printheads 16. In a configuration in which the vertical distance is changed by moving the tray 12 in the vertical direction, the tray support member 30 is preferably also moved vertically together with the tray 12. In the configuration in which the vertical distance is changed in the vertical direction by the head 16, the tray support member 30 is also held in a fixed vertical position while the vertical position of the tray 12 is held fixed.

The vertical movement may be established by a vertical drive 28. Once a layer is completed, the vertical distance between tray 12 and printheads 16 may be increased by a predetermined vertical step (e.g., tray 12 lowered relative to printheads 16) depending on the desired thickness of the layer to be subsequently printed. This process is repeated to form a three-dimensional object in a layered fashion.

The operation of the head 16, and optionally and preferably one or more other components of the system 10, such as the movement of the tray 12, is controlled by a controller 20. The controller may have an electronic circuit and a non-volatile storage medium readable by the circuit, wherein the storage medium stores program instructions that, when read by the circuit, cause the circuit to perform control operations, as described in further detail below.

The controller 20 may also be in communication with a host computer 24 that transmits digital data related to manufacturing instructions based on computer object data in any of the formats described above. The object data format is typically constructed according to a Cartesian coordinate system (Cartesian coordinate system). In these cases, the computer 24 preferably performs a process for converting the coordinates of each slice in the computer object data from a Cartesian coordinate system to a polar coordinate system (polar system of coordinates). The computer 24 optionally and preferably transmits the manufacturing instructions according to the transformed coordinate system. Alternatively, the computer 24 may transmit the manufacturing instructions in accordance with the original coordinate system provided by the computer object data, in which case the coordinate transformation is performed by circuitry of the controller 20.

The transformation of coordinates allows three-dimensional printing on a rotating tray. In conventional three-dimensional printing, the print head reciprocates in a straight line over a fixed tray. In such conventional systems, the print resolution is the same for any point on the tray as long as the dispense rates of the printheads are consistent. Unlike conventional three-dimensional printing, not all of the nozzles of the head cover the same distance on the tray 12 at the same time. The transformation of the coordinates is optionally and preferably performed to ensure that there is an equal amount of excess material at different radial positions. Representative examples of coordinate transformations according to some embodiments of the invention are provided in fig. 3A and 3B, showing three slices of an object (each slice corresponding to manufacturing instructions of a different layer of the object), where fig. 3A shows one slice in a cartesian coordinate system, and fig. 3B shows the same slice after the transformations of the coordinate process are applied to the respective slices.

Generally, as described below, the controller 20 controls voltages applied to various components of the system 10 based on manufacturing instructions and based on stored program instructions.

In general, the controller 20 controls the printheads 16 during rotation of the tray 12 to dispense droplets of build material in layers to print a three-dimensional object on the tray 12.

The system 10 optionally and preferably includes a curing system 18 that may optionally and preferably include one or more radiation sources, which may be, for example, an ultraviolet, visible, or infrared lamp, or other electromagnetic radiation source, or an electron beam source, depending on the modeling material used. The radiation source may comprise any type of radiation emitting device including, but not limited to, light emitting diodes, digital light processing (digital light processing, DLP) systems, resistive lamps, and the like. The curing system 18 is used to cure (e.g., cure) the modeling material. In various exemplary embodiments of the present invention, the operation of curing system 18 is controlled by controller 20, which controller 20 may activate and deactivate curing system 18, and may also optionally control the amount of radiation generated by curing system 18.

In some embodiments of the present invention, system 10 also includes one or more leveling devices 32, which may be manufactured as a roller or a blade. The leveling device 32 is used to straighten a newly formed layer before a continuous layer is formed thereon. In some alternative embodiments, leveling device 32 has the shape of a conical roller positioned such that its axis of symmetry 34 is inclined relative to the surface of tray 12 and its surface is parallel to the surface of the tray. This embodiment is shown in a side view of system 10 (fig. 1C).

The one conical roller may have the shape of a cone or truncated cone (cone).

The opening angle of the cone roller is preferably selected to be a constant ratio between the radius of the cone at any location along its axis 34 and the distance between that location and the axis 14. This embodiment allows the roller 32 to effectively level the layer because the linear velocity of any point p on the roller surface is proportional (e.g., the same) as the linear velocity of the tray vertically below point p as the roller rotates. In some embodiments, the roller has the shape of a frustum of cone, having a height h, a radius R at the nearest distance from the axis 14 ₁ And a radius R at the furthest distance from the axis 14 ₂ Wherein the parameters h, R ₁ R is R ₂ Satisfy the relation R ₁ /R ₂ = (Rh)/h, and where R is the furthest distance of the roll gap axis 14 (e.g., R may be the radius of the tray 12).

Optionally and preferably, controller 20 controls the operation of leveling device 32, and controller 20 may activate and deactivate leveling device 32, and may also optionally control its position along a vertical direction (parallel to axis 14) and/or a radial direction (parallel to tray 12 and directed toward or away from axis 14).

In some embodiments of the invention, the printhead 16 is configured to reciprocate in a radial direction r relative to the tray. These embodiments are useful when the length of the nozzle array 22 of the head 16 is shorter than the width in the radial direction of the working area 26 on the tray 12. Movement of the head 16 in the radial direction is optionally and preferably controlled by a controller 20.

Some alternative embodiments contemplate the manufacture of an object by dispensing different materials from different dispensing heads. These embodiments provide, among other things, the ability to select a material from a given number of materials, and define the desired combination of materials selected and their characteristics. According to this embodiment, the spatial locations of each material and the deposition of the layer are defined to enable the different three-dimensional locations to be occupied by different materials, or to enable the substantially same three-dimensional locations or adjacent three-dimensional locations to be occupied by two or more different materials, thereby allowing post-deposition spatial combinations of materials, such as numerical combinations of materials within the layer, to form a third material at a corresponding location or locations.

Any post-deposition combination or mixing of build materials is contemplated. For example, when a particular material is dispensed, it may retain its original properties. However, when it is dispensed simultaneously with another modeling material or other dispensed material that is dispensed at the same or nearby location, a composite material is formed that has one or more characteristics that are different from the material being dispensed.

Thus, embodiments of the present invention are capable of depositing a wide range of combinations of materials in different portions of an object, as well as fabricating an object that may be composed of a plurality of different combinations of materials, depending on the characteristics required to characterize each portion of the object.

An exemplary embodiment of printhead 16 is shown in fig. 2A-2C. These embodiments may be used in any of the additive manufacturing systems described above, including but not limited to system 110 and system 10.

Fig. 2A-2B illustrate a printhead 16 having one (fig. 2A) and two (fig. 2B) nozzle arrays 22. The nozzles in the array are preferably aligned linearly along a straight line. In embodiments where a particular printhead has two or more linear nozzle arrays, the nozzle arrays are optionally and preferably parallel to each other.

When a system similar to system 110 is employed, all printheads 16 are optionally and preferably oriented along an indexing direction (indexing direction) and the positions of all printheads 16 along a scanning direction are offset from one another.

When a system similar to system 10 is employed, all printheads 16 are optionally and preferably oriented radially (parallel to the radial direction) with their azimuthal positions offset from one another. Thus, in these embodiments, the nozzle arrays of different printheads are not parallel to each other, but are at an angle to each other that is approximately equal to the azimuthal offset between the individual printheads. For example, one head may be radially oriented and positioned in an azimuthal position While the other head can be oriented radially and positioned in azimuth position +.>In this example, the azimuthal offset between the two heads is +.>And the angle between the linear nozzle arrays of the two heads is also +.>In some embodiments, two or more printheads may be assembled to a block of printheads, in which case the printheads of the block are generally parallel to one another. In fig. 2C a block comprising a plurality of heads 16a, 16b, 16C is shown.

Fig. 4 is a schematic diagram of an additive manufacturing full color system according to some embodiments of the invention. In general, additive manufacturing system 600 (i.e., the apparatus) is a three-dimensional inkjet printing apparatus that includes a build material supply system or apparatus 630, and a print block or frame 620 that scans a surface or tray 660 of a build. In one embodiment of the invention, build material supply system 630 includes six liquid build material supply cartridges for supplying six different liquid build materials to additive manufacturing system 600 via material reservoirs 625. To print the object 650, the box "C" supplies a cyan mold material, the box "M" supplies a magenta mold material, the box "Y" supplies a yellow mold material, the box "W" supplies a white mold material, and the box "K" supplies a black mold material. The cassette "S" supplies a soft material that may be used to form the intermediate structure 651 and/or form a portion of a support structure required to print the three-dimensional object 650. According to some embodiments of the present invention, a cartridge "K" is provided in place of the black mold material, with a black flexible material, to print at least a portion of the peelable sacrificial structures 652 as well as some areas of the object itself. The soft material forming the intermediate structure 651 can be selected to have a pasty consistency, and optionally can be selected to be water washable.

In some embodiments of the invention, print block 620 includes up to three inkjet printheads 616 for selectively depositing build material on tray 660. Each printhead 616 receives build material from two of the six cartridges of supply 630 via material reservoir 625. Each printhead has two linear arrays of nozzles 624, for example as shown in fig. 2B, each dedicated to dispensing a different building material supplied by a supply device 630. Alternatively, two or more nozzle arrays may be dedicated to dispensing the same material.

Typically, the printing block 620 further comprises a leveling device 670 for leveling a printing layer, and one or more hardening devices 680 for hardening the printing layer.

The print block 620 is preferably operable to reciprocate on a tray 660 that serves as a work surface. The tray 660 is horizontally placed. According to common practice, an XYZ Cartesian coordinate system is selected such that the X-Y plane is parallel to the tray 660. In some exemplary embodiments, print block 620 moves along a scan direction (referred to herein as the X-direction) and printheads 616 selectively dispense build material in a predetermined configuration as they pass over tray 660. The printhead 616 is then cured by, for example, curing the build material using one of the curing devices 680. In the reverse pass of print block 620, returning to the start of its just deposited layer, an additional dispensing of build material may be performed according to the predetermined configuration. Then, another hardening device 680 is operated. Alternatively, both stiffening means operate in one or both directions.

In the forward and/or reverse pass of the print block 620, the formed layers may be straightened by a leveling device 670, said leveling device 670 preferably following a path of forward and/or backward movement of the print head 616. Once the print block 620 returns to its starting point along the X-direction, it can move to another position along an indexing direction (referred to herein as the Y-direction) and continue building the same layer by reciprocating along the X-direction. Alternatively, print block 620 may move in the Y direction between forward and backward movements or after more than one forward-backward movement. The series of scans performed by the dispense head to complete a single layer is referred to herein as a single scan cycle.

Once the layer is complete, the tray 660 is lowered in the Z direction to a predetermined Z level, depending on the desired thickness of the layer to be subsequently printed. This process is repeated to form the three-dimensional object 650 in a layered fashion.

A control unit 640 controls the operation of the elements included in the building supply system 630 and the print block 620. The control unit 640 typically includes an electronic circuit configured to perform control operations. The control unit 640 is preferably in communication with a processor 641, the processor 641 sending digital data relating to manufacturing instructions based on computer object data (e.g., a CAD configuration represented on a computer readable medium in a standard tessellation language format, etc.). In general, the processor 641 includes a memory unit and/or memory capability for storing computer object data and for storing data related to manufacturing instructions based on the computer object data. In general, the control unit 640 controls elements of the print block 620, such as voltages applied to each printhead 616 or each nozzle array 624, the hardening unit 680, and the roller 670, and supply of building material from each of the six cartridges 631 in the building material supply apparatus 630.

Once the manufacturing data is loaded into control unit 640, additive manufacturing system 600 can be run without user intervention. In some embodiments, the control unit 640 receives additional input from an operator, for example, using the data processor 641 or using a user interface 642 in communication with the unit 640.

Fig. 5A and 5B are exemplary top and perspective views of a material reservoir of an additive manufacturing system according to some embodiments of the present invention. The material reservoir 625 includes a plurality of separate compartments 608 for directing build material from the supply system 630 to the printheads 616 (see FIG. 4). Each compartment 608 of the material reservoir 625 may be shaped as a defined channel having one or more outlets through which material is introduced into a printhead 616. Optionally, an outlet is positioned at each end 609 of the compartment 608. According to some embodiments of the invention, compartment 608a is designed to supply two different build materials to two different nozzle arrays in a first printhead 616, compartment 608b is designed to supply two different build materials to two different nozzle arrays in a second printhead 616, and compartment 608c is designed to supply two different build materials to two different nozzle arrays in a third printhead 616. Typically, the first array and the second array of a single printhead 616 do not overlap, and both arrays can be used to print two different build materials simultaneously.

In one exemplary configuration, the reservoir 625 arranges the modeling material in four different colors plus soft material and a flexible black material. Thus, six different build materials are deposited, i.e., dispensed through three dual nozzle array printheads 616, and a full color three-dimensional object 650 is produced, as well as a peelable flexible sacrificial structure that is easily removed, for example, in a home or office environment.

Fig. 6 is a flow chart of a method according to various exemplary embodiments of the invention. The method may be used to fabricate any object having a peelable sacrificial structure, including but not limited to an artificial medical structure (e.g., a dental structure), a mold, and a housing for an electronic device.

The method begins at 200, and optionally and preferably proceeds to 201, where computer object data is received in any of the aforementioned formats at 201. The method may proceed to 202 where a layer of build material is dispensed 202. The build material may be a mold material, a flexible material, and/or a soft material. In some embodiments of the invention, the method selectively dispenses one or more regions of modeling material, one or more regions of flexible material, and one or more regions of flexible material for a particular layer. The model material is preferably dispensed in a configuration pattern corresponding to the shape of the object and in accordance with the computer object data.

The method optionally and preferably proceeds to 203 where the dispensed build material is cured 203. The type of curing process depends on the type of material being dispensed. For example, when the build material is uv curable, curing includes applying uv radiation, and when the build material is curable by other radiation (e.g., infrared or visible light), curing includes applying radiation of a wavelength that cures the build material.

Operations 202 and 203, and in some embodiments also preferably 201, are performed sequentially a plurality of times, sequentially dispensing and curing a plurality of layers, and completing object data or defined blocks 204 of the plurality of layers. This is shown in fig. 6 as a loop back arrow from operation 204 to operation 201. Alternatively, operation 204 may loop back to operation 202. The multiple layers are dispensed to form a three-dimensional object that includes primarily solid modeling material (e.g., 51 to 100%); a sacrificial structure comprising essentially a flexible material (e.g., 80 to 100%); and an intermediate structure consisting essentially of a soft material (e.g., 80 to 100%). In some embodiments of the invention, the method dispenses digital material for at least one layer.

Once all layers are formed, the method preferably proceeds to 205 by applying a peel force to the sacrificial structure to separate the sacrificial structure from the three-dimensional object, preferably in its entirety, along with a portion or all of the soft material used as an intermediate structure, from the three-dimensional object at 205. Preferably, the stripping is performed in a dry environment. According to some of any of the embodiments of the invention described herein, the peel force is about 1 newton (N) to about 20N, for example about 5N, about 10N, or about 15N. Optionally, once the sacrificial structure is removed, the three-dimensional object is preferably washed with an environmentally friendly liquid (e.g., water) to remove residues of soft material on its surface.

The method ends at 206.

According to some embodiments of the present invention, the sacrificial structures are removed by lift-off, unlike conventional techniques in which water jets (water jets) or other chemical methods are employed, such as dissolution in a solvent with or without heating.

The inventors have found that in many cases, conventional support removal may involve hazardous materials, physical labor, and/or special equipment requiring trained personnel, protective clothing, and expensive waste disposal. The inventors have appreciated that the dissolution process may be limited by diffusion kinetics and may take a long time. The inventors have also recognized that in some cases, a post-treatment must be performed to remove traces of residual material from the object surface, such as support material or hardened mold material and mixtures of support materials. The inventors have also recognized that the need for elevated temperature removal can also be problematic, as this can be inconvenient and require specialized equipment.

To address these issues, the present inventors devised a fabrication technique that facilitates removal of sacrificial structures by lift-off without the need for water jets, chemical processes, and/or high temperatures. The effective removal of the sacrificial structure by lift-off can be ensured in more than one way.

In some embodiments of the invention, the sacrificial structure comprises a stack of sacrificial layers made of a flexible material. Any flexible material, such as an elastomeric material, may be used. A representative example of an elastomeric material suitable for use as an elastomeric material in accordance with some embodiments of the present invention is provided below and described in further detail in international patent application entitled "additive manufacturing of rubber-like materials (ADDITIVE MANUFACTURING OF RUBBER-LIKE MATERIALS)", which claims priority from U.S. provisional patent application No. 62/342,970 filed on month 29 of 2016, the entire contents of which are incorporated herein by reference.

Fig. 7A is a simplified flow chart of an exemplary method of supporting a printed object using a combination of soft and flexible materials, according to some embodiments of the present invention. According to some example embodiments, a support structure for an object printed by a three-dimensional inkjet additive manufacturing system may comprise two different materials. One material may be a flexible material, such as an elastomeric material, configured to form a peelable structure for peeling from an object at the end of a printing process as described herein, while another material may be a soft material that may be used to provide an intermediate soft structure between the object and the peelable material, and to fill difficult-to-reach volumes, such as partially enclosed volumes, from which the sacrificial structure cannot be peeled.

Alternatively, the soft material may be water-soluble, for example, a gel-like photopolymer which can be removed by immersion in water without any special equipment. Alternatively, the soft material may be support material SUP705 ^TM 、SUP706 ^TM Or SUP707 ^TM Or a combination thereof, all of which are listed in israelSupplied by the company limited. Alternatively, the soft material may have a pasty consistency and may also optionally be chosen to be washable.

In some exemplary embodiments, the flexible peelable material may be formed, for example, as follows: from TangoPlus ^TM FLX 930 (Shore 27A), tangoBlackPlus ^TM FLX 980 (Shore 27A), tangoGray ^TM FLX950 (Shore 70A), tangoBlack ^TM FLX973 (Shore 70A), agils 30 ^TM Clear FLX935 (Shore 30A) or Agils 30 ^TM Black FLX985 (Shore 30A) or combinations thereof, all listed in IsraelSupplied by the company limited. Alternatively or additionally, the flexible peelable material may be formed of a dedicated formulation, e.g. from Israel +.>Company SUP705 ^TM 、SUP706 ^TM And/or Vero ^TM A digital combination of materials.

According to some exemplary embodiments, the method starts with received computer object data (505). The computer object data may include regions that are printed primarily using model material to form a three-dimensional object, and regions that are printed primarily using other build materials, such as flexible and/or soft materials, to form a support structure. An area to be used as a support structure may be identified (510) and distinguished from an area to be printed using the modeling material. Portions of the support structure may be printed (515) using a flexible peelable material, such as an elastic material, and other portions of the support structure may optionally be printed (520) using a soft material. Based on the selection, printing is performed (525). After printing, a user may peel off the flexible material and optionally rinse or dip the object with any residue of the flexible material still attached to it to dissolve the remaining flexible material and provide a clean printed object entirely.

In some exemplary embodiments, the soft material is printed to fill deep, narrow holes, or any other difficult to reach and/or hide volume (e.g., a partially enclosed volume) that may be defined by the object structure. Soft materials may also be used to protect delicate features of three-dimensional objects that may be prone to breakage if a pulling or peeling force is applied in the vicinity of the delicate features. In some exemplary embodiments, the soft material provides an intermediate structure between the object to be printed and the sacrificial structure made of a flexible material to facilitate separation of the sacrificial structure from the object. The thickness of the soft material may be, for example, 1 to 10 voxels, 1 to 25 voxels, 1 to 50 voxels, or 10 to 200 micrometers (μm), 10 to 500 μm, or 10 to 1000 μm. Alternatively, the thickness of the soft material may be a function of orientation. In some exemplary embodiments, a spacer layer of soft material may be defined as being thinner in a Z direction (vertical direction) as compared to a horizontal spacer layer. The thickness of the spacer layer may also be a function of the printer properties, physical, chemical and/or other characteristics of one or more materials used to construct the object.

The mechanical properties of the flexible material that can be peeled off depend on its thickness and geometry. Alternatively, the thickness of the flexible peelable material may be defined based on a desired mechanical property. For example, a thinner layer of releasable material may be more flexible and may be easier to release than a thicker layer. Optionally, at least a portion of the sacrificial structure formed of a flexible peelable material has a flexural modulus of between 2000 megapascals (MPa) and 4000MPa. Alternatively, a combination of flexible materials that are peelable may be used to define a pattern, such as a grid, and soft materials may be defined to achieve a desired mechanical property.

Fig. 7B is a simplified flowchart of an exemplary method of color printing with an additive manufacturing system, according to some embodiments of the present invention. Alternatively, an additive manufacturing system may not include a black mold (i.e., solid) material, but may use a black flexible material. The method begins by identifying computer object data corresponding to an area of a three-dimensional object to be printed in black (530). According to some exemplary embodiments, a combination of different colored model materials (e.g., CMY), black alone flexible materials, or a combination of colored model materials and black flexible materials may be used to print a black portion or element in an object to be printed. In some exemplary embodiments, a decision is made between printing a black area using only black flexible material or a combination with model material. Alternatively, if the data to be printed in black is part of a large volume within the object designated to be printed in black (535), then this area may be printed using different colored model materials that are digitally combined to create a black model material, optionally in combination with a quantity of black flexible material (550). Otherwise, when the data printed in black is part of a small volume, this area is preferably printed using a flexible material that is black to obtain true black and reduce the consumption of building material for this purpose (540). For fine external details or structures of the object surface, a combination of multiple build materials is preferably used in order to preserve surface properties (e.g., thin walls).

Fig. 8A and 8B are schematic illustrations of two different configurations of printing an object having a peelable flexible material and an intermediate flexible structure, according to some embodiments of the invention. The flexible material that can be peeled off is, for example, an elastomer material that forms a sacrificial structure. During layer build, an object 715 or 716 is layered and enclosed in a sacrificial structure 706 formed of soft material 710 and peelable flexible material 705. In some exemplary embodiments, portions of the flexible material 705 printed with the peelable may be split. In some examples, the partitioning may be performed by splitting the sacrificial structure into multiple portions to easily remove the peelable material 705, such as by separating the multiple portions of the peelable material 705 using strips of soft material 710. In other examples, the split may be formed by breaking or otherwise forming, such as using strips 710 of exposed (i.e., visible at the surface of the sacrificial structure) soft material to separate a surface of the flexible material 705 that is peelable for further removal. Referring now to fig. 8B of object 716, in some exemplary embodiments, a tab 755 may optionally be formed from a peelable flexible material 705 to facilitate grasping of the flexible material to initiate its removal. Alternatively, the peelable flexible material 705 may be split, for example, near the tab 755, for example, by a soft material 710 that may be exposed at the surface of the slit.

Fig. 9A and 9B are schematic illustrations of two different configurations for printing an object comprising a large support volume, the object having a peelable flexible material 705 and an intermediate structure of soft material 710 around it, according to some embodiments of the invention. When a large volume of support, sacrificial structure 706, is applied to build object 717, the bulk of the peelable flexible material 705 in sacrificial structure 706 may be difficult to remove at the end of the printing process. In some exemplary embodiments, soft material 710 may be applied to fill a portion of volume 706. Optionally, the soft material 710 may be encapsulated with a flexible material 705 that is peelable. Addition of soft material 710 softens volume 706 so that it can be removed more easily. In addition, by encapsulating soft material 710 with peelable flexible material 705, volume 706 can be removed while preserving soft material 710 contained in peelable flexible material 705, thereby avoiding any potential confusion or residue that may occur when soft material 710 is removed, and improving the mechanical properties of printed object 717.

Fig. 10A and 10B are schematic illustrations of an object 718 having a closed loop geometry and printed with a sacrificial structure 706 comprising a peelable flexible material and an intermediate flexible structure, according to some embodiments of the invention. Fig. 10A is a cross-section of an exemplary closed loop object printed vertically with respect to a tray or printing surface, and fig. 10B is a schematic three-dimensional image of a closed loop object printed horizontally with respect to a tray or printing surface. In both cases, when printing an object 718 having a closed loop geometry and a hollow 707, the sacrificial structure 706 required to form the object may be difficult to remove, i.e., to delaminate when printing is completed. In this case, to simplify the peeling process, the peelable flexible material 705 can be defined as a slit printed with soft material along at least a portion of an inner and/or outer circumference of the object 718, from which the flexible material 705 can be peeled after the printing process. Soft material 710 may be exposed at the fracture and may provide for separation of the peelable flexible material 705 at the fracture (e.g., as shown in fig. 10B). The slit may facilitate removal of the flexible material 705 from an object 718 having a closed loop geometry.

FIGS. 11A, 11B and 11C are all schematic side views of three different configurations for printing an object including an aperture with a sacrificial structure formed of a flexible material that is peelable and an intermediate soft structure surrounding the object in accordance with some embodiments of the invention. In some exemplary embodiments, the geometry of an object 719 may define a cavity 729 having a narrow opening. The build object 719, as shown in fig. 11A, may include a large mass of flexible peelable material 705 within the cavity 729. In this configuration, it may be difficult to peel the flexible material 705 from the cavity 729. Alternatively, the object 719 may be defined as printing with the soft support material 710 filling the cavity 729, as shown in fig. 11B, or printing with the soft support material 710 filling a majority of the cavity 729, and the flexible material 705 penetrating partially into the cavity 729 in a taper, as shown in fig. 11C, so that the flexible material 705 may be easily removed. In the configuration shown in fig. 11C, the cleaning time may be reduced based on the reduction in volume of the soft support material 710, as compared to the configuration shown in fig. 11B.

Fig. 12A, 12B and 12C are all schematic illustrations of three different configurations for printing an object including a high aspect ratio cavity surrounded by a sacrificial structure including a peelable flexible material and an intermediate flexible structure, according to some embodiments of the invention. The object 720 includes a high aspect ratio cavity 721. In one configuration, as shown in fig. 12A, the cavity 721 may be filled with a flexible material 705 during printing. In some exemplary embodiments, based on the configuration shown in fig. 12A, it may be difficult to remove the flexible material 705 at the end of the printing process. Due to the geometry of the cavity 721, the shear forces applied when pulling the flexible material 705 may fracture the flexible material 705, making it difficult to completely separate the object 720 from the sacrificial structure. Alternatively, in some exemplary embodiments, cavity 721 may be defined as being completely filled with soft material 710, as shown in fig. 12B, or partially filled with soft material 710, as shown in fig. 12C. In the example shown in fig. 12C, the object 720 is printed with a flexible material 705, which flexible material 705 penetrates into the cavity 721 in a tapered geometry in order to be easily separated from the object 720 at the end of the printing process.

FIGS. 13A, 13B and 13C are all schematic illustrations of three different configurations for printing an object including a fine feature surrounded by flexible material forming a sacrificial structure, according to some embodiments of the invention. The object 722 may include one fine feature 723 or more than one fine feature. In some exemplary embodiments, it may be desirable to use a thicker layer of soft material 710 to cover the fine features 723 of the object 722 to avoid damaging the fine features 723 while pulling the soft material 705 to expose the object 722 at the end of the printing process.

In some exemplary embodiments, as shown in fig. 13A, a layer of soft material 710 having substantially the same thickness around object 722 may not be sufficient to protect fine features 723. Alternatively, in some exemplary embodiments, the fine features 723 may be identified prior to printing, and a thicker layer of soft material 710 may be selected to cover the fine features 723, as shown in fig. 13B and 13C. The thickness and shape of the layer of soft material 710 around the fine feature 723 may be tailored to provide adequate protection while saving the amount of material needed to provide protection and saving the cleaning time associated with removing soft material 710. An alternative arrangement with less support material (e.g., flexible peelable material and/or soft material) is shown, for example, in fig. 13C.

The following is a description of an elastomeric material suitable for use as a flexible material according to some embodiments of the present invention.

The elastomeric formulation described herein comprises an elastomeric material. Optionally and preferably, the elastomeric formulation further comprises silica particles.

The phrase "elastomeric material" describes a curable (e.g., curable) material as defined herein that obtains the characteristics of an elastomer (a rubber or rubber-like material) upon curing (e.g., upon exposure to energy, such as but not limited to curing energy).

The elastomeric material typically comprises one or more polymerizable (curable) groups that polymerize upon exposure to a suitable curing energy to attach to a portion of the elasticity imparted to the polymerized and/or crosslinked material. Such moieties typically comprise alkyl, alkylene chains, hydrocarbon groups, alkylene glycol groups or chains (e.g., oligo-or poly (alkylene glycol) as defined herein, polyurethane, oligo-or polyurethane groups as defined herein, and the like, including any combination thereof, and are also referred to herein as "elastomeric moieties".

An elastomeric monofunctional curable material according to some embodiments of the present invention may be a vinyl-containing compound represented by formula I:

Wherein R is ₁ R is R ₂ Is and/or comprises an elastomeric portion, as described herein.

(=ch) in formula I ₂ ) The group represents a polymerizable group and, according to some embodiments, is a uv curable group such that the flexible material is a uv curable material.

For example, R ₁ Is or comprises an elastomeric moiety as defined herein, and R ₂ For example hydrogen, C (1-4) alkyl, C (1-4) alkoxy or any other substituent, provided that it does not interfere with the elastomeric properties of the cured material.

In some embodiments, R ₁ Is a carboxylate salt, and the compound is a monofunctional acrylate monomer. In some of these embodiments, R ₂ Is methyl, and the compound is a monofunctional methacrylate monomer. Curable material, wherein R ₁ Is a carboxylate and R ₂ Is hydrogen or methyl, collectively referred to herein as "(meth) acrylate".

In some of any of these embodiments, the carboxylic acid group-C (=o) -ORa comprises Ra, ra being an elastomeric moiety as described herein.

In some embodiments, R ₁ Is an amide, and the compound is a monofunctional acrylamide monomer. In some of these embodiments, R ₂ Is methyl, and the compound is a monofunctional methacrylamide monomer. Curable material, wherein R ₁ Is an amide and R ₂ Is hydrogen or methyl, collectively referred to herein as "(meth) acrylamide".

(meth) acrylates and (meth) acrylamides are collectively referred to herein as (meth) acrylic materials.

In some embodiments, R ₁ Is a cyclic amide, and in some embodiments, R ₁ Is a cyclic amide, such as a lactam, and the compound is a vinyl lactam (vinyl lactam). In some embodiments, R ₁ Is a cyclic carboxylate, such as a lactone, and the compound is a vinyl lactone (vinyl lactone).

When R is ₁ R is R ₂ Where one or both comprise a polymeric or oligomeric moiety, the monofunctional curable compound of formula I is a typical polymeric or oligomeric monofunctional curable material. Otherwise, it is a typical monomeric monofunctional curable material.

In the multifunctional elastomeric materials, two or more polymerizable groups are connected to each other via an elastomeric portion, as described herein.

In some embodiments, a multifunctional elastomeric material may be represented by formula I, as described herein, wherein R ₁ Comprising an elastomeric material terminated by a polymerizable group as described herein.

For example, a difunctional elastomeric material may be represented by formula I:

wherein E is an elastomeric linking moiety as described herein, and R' ₂ As for R herein ₂ Defined as follows.

In another example, a trifunctional elastomeric material may be represented by formula II:

wherein E is an elastomeric linking moiety as described herein, and R' ₂ R' and its use " ₂ Each independently as herein for R ₂ Defined as follows.

In some embodiments, a multifunctional (e.g., difunctional, trifunctional, or higher) elastomeric material may be collectively represented by formula III:

wherein:

R ₂ r 'and R' ₂ As defined herein;

b is a mono-or tri-functional branching unit as defined herein (depending on X ₁ Properties of (2);

X ₂ x is X ₃ Each independently absent; an elastomeric portion as described herein; or selected from the group consisting of an alkyl group, a hydrocarbyl group, an alkylene chain, a cycloalkyl group, an aryl group, an alkylene glycol, a carbamate moiety, and any combination thereof; and

X ₁ absent or selected from an alkyl, a hydrocarbyl, an alkylene chain, a cycloalkyl, an aryl, an alkylene glycol, a urethane moiety and an elastomeric moiety, each optionally interrupted by a methyl (acrylate) moiety (O-C (=o) CR' ₂ ＝CH ₂ ) Substitution (e.g., termination), and any combination thereof, or X ₁ The method comprises the following steps:

wherein: b' is a branching unit, identical to or different from B.

X’ ₂ X's' ₃ Respectively and individually as for X herein ₂ X is X ₃ Is defined as follows; and

R” ₂ r ', R'. ₂ As for R herein ₂ R 'and R' ₂ Is defined in (a).

Provided that X ₁ 、X ₂ X is X ₃ Is or comprises an elastomeric portion as described herein.

The term "branching unit" as used herein describes a multi-radical, preferably aliphatic or cycloaliphatic radical. By "multi-radical" is meant that the linking moiety has two or more points of attachment such that it is linked between two or more atoms and/or groups or moieties.

That is, a branching unit is a chemical moiety that, when attached to a single position, group or atom of a substance, produces two or more functional groups attached to the single position, group or atom, thereby "branching" a single functional group into two or more functional groups.

In some embodiments, the branching unit is derived from a chemical moiety having 2, 3, or more functional groups. In some embodiments, the branching unit is a branched alkyl group or a branched linking moiety as described herein.

Also contemplated are multifunctional elastomeric materials having 4 or more polymerizable groups and may have a structure similar to that shown in formula III, including, for example, branching units B having a higher degree of branching, or X having two (meth) acrylate moieties ₁ Moieties, as defined herein or similar to those shown in formula II, also include, for example, another (meth) acrylate moiety attached to the elastomeric moiety.

In some embodiments, the elastomeric moiety, e.g., ra in formula I, or the moiety represented as E in formulas I, II, and III, is or comprises: alkyl groups, which may be linear or branched, and preferably have 3 or more, or 4 or more carbon atoms; alkylene chains, preferably 3 or more, or 4 or more carbon atoms in length; an alkylene glycol as defined herein, an oligo (alkylene glycol) or poly (alkylene glycol) as defined herein, preferably 4 or more atoms in length; a urethane, urethane oligomer or polyurethane as defined herein, preferably having a length of 4 or more carbon atoms; and any combination of the foregoing.

In some embodiments of any of the embodiments described herein, the elastomeric material is a mono (meth) acrylic curable material described herein, and in some embodiments, it is an acrylate.

In some embodiments of any of the embodiments described herein, the elastomeric material is or includes a monofunctional elastomeric material, and in some embodiments, the monofunctional elastomeric material is represented by formula I, wherein R ₁ is-C (=o) -ORa, and Ra is a mono-alkylene chain (e.g., of length 4 or more, preferably 6 or more, preferably 8 or more carbon atoms), or a poly (alkylene glycol) chain as defined herein.

In some embodiments, the elastomeric material is or includes a multifunctional elastomeric material, and in some embodiments, the multifunctional elastomeric material is represented by formula I, wherein E is an alkylene chain (e.g., of length 4 or more, or 6 or more carbon atoms), and/or a poly (alkylene glycol) chain as defined herein.

In some embodiments, the elastomeric material is or includes a multifunctional elastomeric material, and in some embodiments, the multifunctional elastomeric material is represented by formula II, wherein E is a branched alkyl group (e.g., of 3 or more, 4 or more, or 5 or more carbon atoms in length).

In some embodiments of any of the embodiments described herein, the elastomeric material is an elastomeric acrylate or methacrylate (also referred to as an acrylic or methacrylic elastomer) of formula I, I, II or III, for example, and in some embodiments, the acrylate or methacrylate is selected such that, upon hardening, a Tg of the polymeric material is below 0 ℃ or below-10 ℃.

Exemplary elastomeric acrylate and methacrylate curable materials include, but are not limited to: 2-acrylic acid,2- [ [ ((butylamino) carbonyl ] oxy ] ethyl ester (2-propenoic acid,2- [ [ (butylamino) carbonyl ] ethyl ester) (an exemplary urethane acrylate (uretheane acrylate)), and compounds sold under the trade names SR335 (Lauryl acrylate) and SR395 (isodecyl acrylate (isodecyl acrylate)), other examples include compounds sold under the trade names SR350D (trifunctional trimethylol propane trimethacrylate (trifunctional trimethylolpropane trimethacrylate, TMPTMA)), SR256 (2- (2-ethoxyethoxy) ethyl acrylate), SR252 (polyethylene glycol (600) dimethacrylate (polyethylene glycol (600)) and SR561 (alkoxylated hexanediol diacrylate (alkoxylated hexane diol diacrylate)).

In some embodiments of any of the embodiments described herein, the elastomeric material includes one or more monofunctional elastomeric materials (e.g., a monofunctional elastomeric acrylate, such as shown in formula I), and one or more multifunctional (e.g., difunctional) elastomeric materials (e.g., a difunctional elastomeric acrylate, such as shown in formula I, II, or III), and in any corresponding embodiment described herein.

In some embodiments of any of the embodiments described herein, a total amount of elastomeric material(s) is at least 40%, at least 50%, or at least 60%, and may be up to 70% or even 80% of the total weight of the elastomeric formulation comprising the elastomeric material.

In some embodiments of any of the embodiments described herein, the elastomeric formulation further comprises silica particles.

In some of any of the embodiments described herein, the silica particles have an average particle size of less than 1 μm, i.e., the silica particles are submicron particles. In some embodiments, the silica particles are nanoparticles and a mean particle diameter ranging from 0.1 μm to 900 nanometers (nm), from 0.1nm to 700nm, from 1nm to 500nm, or from 1nm to 200nm, including any intermediate values and subranges therebetween.

In some embodiments, at least a portion of such particles may aggregate when introduced into the formulation. In some of these embodiments, the aggregate has an average size of no more than 3 μm, or no more than 1.5 μm.

In the context of this embodiment, any commercially available formulation of submicron silica particles may be used, including fumed silica (fused silica), colloidal silica (colloidal silica), precipitated silica (precipitated silica), layered silica (e.g., montmorillonite), and aerosol assisted self-assembled silica particles (aerosol assisted self-assembly of silica particles).

The silica particles may be characterized by a hydrophobic or a hydrophilic surface. The nature of the hydrophobicity or hydrophilicity of the particle surface depends on the nature of the surface groups on the particle.

When the silica is untreated, i.e., consists essentially of Si and O atoms, the particles typically have silanol (Si-OH) surface groups and are therefore hydrophilic. Untreated (or uncoated) colloidal silica, fumed silica, precipitated silica, and layered silica all have hydrophilic surfaces and are considered hydrophilic silica.

The layered silica may be treated to feature long chain hydrocarbons terminated with quaternary ammonium and/or ammonium as surface groups, and its surface properties are determined by the length of the hydrocarbon chains. Hydrophobic silica is a form of silica in which hydrophobic groups are bonded to the surface of the particle, also known as treated silica or functionalized silica (silica reacts with hydrophobic groups).

Silica particles having hydrophobic surface groups such as, but not limited to: alkyl groups, preferably medium to higher alkyl groups, cycloalkyl groups, aryl groups of 2 or more carbon atoms in length, preferably 4 or more, or 6 or more carbon atoms, and other hydrocarbons as defined herein, or hydrophobic polymers (e.g., polydimethylsiloxane), are particles of hydrophobic silica.

Thus, the silica particles described herein may be untreated (unfunctionalized) and thus hydrophilic particles.

Alternatively, the silica particles described herein may be treated or functionalized by reaction to form bonds with moieties on their surface.

When the moiety is a hydrophilic moiety, the functionalized silica particles are hydrophilic.

Silica particles having hydrophilic surface groups (such as, but not limited to, hydroxyl, amine, ammonium, carboxyl, silanol, oxo, etc.) are particles of hydrophilic silica.

When the moiety is a hydrophobic moiety, the functionalized silica particles are hydrophobic as described herein.

In some of any of the embodiments described herein, at least a portion or all of the silica particles have a hydrophilic surface (i.e., hydrophilic silica particles such as untreated silica, e.g., colloidal silica).

In some embodiments of any of the embodiments described herein, at least a portion or all of the silica particles have a hydrophobic surface (i.e., hydrophobic silica particles).

In some embodiments, the hydrophobic silica particles are functionalized silica particles, i.e., silica particles treated with one or more hydrophobic moieties.

In some embodiments of any of the embodiments described herein, at least a portion or all of the silica particles are hydrophobic silica particles functionalized with curable functional groups (particles having curable groups on their surfaces).

The curable functional groups may be any of the polymerizable groups described herein. In some embodiments, the curable functional groups may be polymerizable by the same polymerization reaction as the curable monomers in the formulation and/or when exposed to the same curing conditions as the curable monomers. In some embodiments, the curable group is a (meth) acrylic (acrylic or methacrylic) group, as defined herein.

The hydrophilic and hydrophobic, functionalized and untreated silica particles described herein may be commercially available materials or may be prepared using methods well known in the art.

As used in the context of these embodiments, "at least a portion" refers to at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% of the particles.

The silica particles may also be a mixture of two or more types of silica particles, for example, two or more of any of the silica particles described herein.

In some embodiments of any of the embodiments described herein, a content of the silica particles in a modeling material formulation comprising silica particles is in a range of about 1% to about 20%, about 1% to about 15%, or about 1% to about 10% by weight of the total weight of the elastomeric formulation.

The content of silica particles can be controlled as desired to control the mechanical properties of the cured material. For example, higher amounts of silica particles may result in higher elastic moduli of the cured sacrificial structures.

In some of any of the embodiments described herein, the silica particles are present in an amount such that a weight ratio of elastomeric material(s) to silica particles in the elastomeric formulation is about 50:1 to about 4:1, or about 30:1 to about 4:1, or about 20:1 to about 2:1, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the elastomeric formulation further comprises one or more additional curable materials.

The additional curable material may be a monofunctional curable material, a polyfunctional curable material, or mixtures thereof, and each material may be a monomer, an oligomer, or a polymer, or combinations thereof.

Preferably, but not necessarily, the additional curable material is polymerizable when exposed to the same curing energy as the curable elastomeric material is polymerizable, for example when exposed to radiation (e.g., ultraviolet-visible radiation).

In some embodiments, the additional curable material is such that when cured, the Tg of the polymeric material is higher than the Tg of an elastomeric material, e.g., a Tg higher than 0 ℃, 5 ℃, or higher than 10 ℃.

Throughout, "Tg" refers to the glass transition temperature, defined as the location of the local maximum of the E "curve, where E" is the loss modulus of a material as a function of temperature.

Broadly, as the temperature increases over a temperature range including the Tg, the state of a material, particularly a polymeric material, gradually changes from a glassy state to a rubbery state.

Herein, a "Tg range" is a temperature range where the E "value is at least half of its value (e.g., its value can be reached) at the Tg temperature as defined above.

Without wishing to be bound by any particular theory, it is assumed that the state of a polymeric material gradually changes from glassy to rubbery within the Tg range defined above. Herein, the term "Tg" refers to any temperature within the Tg ranges defined herein.

In some embodiments, the additional curable material is a monofunctional acrylate or methacrylate ((meth) acrylate). Non-limiting examples include: isobornyl acrylate (isobornyl acrylate, IBOA), isobornyl methacrylate (isobornyl methacrylate), acryloylmorpholine (acryloyl morpholine, ACMO), phenoxyethyl acrylate (phenoxyethyl acrylate), sold by Sartomer company (usa) under the trade name SR-339; urethane acrylate oligomer (urethane acrylate oligomer), such as sold under the trade name CN 131B, as well as any other acrylates and methacrylates that can be used in additive manufacturing processes.

In some embodiments, the additional curable material is a multifunctional acrylate or methacrylate ((meth) acrylate). Non-limiting examples of multifunctional (meth) acrylates include propoxylated (2) neopentyl glycol diacrylate (pro-oxidized (2) neopentyl glycol diacrylate), sold by Sartomer company (U.S.A.) under the trade name SR-9003; ditrimethylolpropane tetraacrylate (Ditrimethylolpropane Tetra-acrylate, ditmpta), pentaerythritol tetraacrylate (Pentaerythitol Tetra-acrylate, TETTA), dipentaerythritol pentaacrylate (Dipentaerythitol Penta-acrylate, diPEP) and aliphatic urethane diacrylate (aliphatic urethane diacrylate), for example sold under the trade name Ebecryl 230. Non-limiting examples of multifunctional (meth) acrylate oligomers include ethoxylated or methoxylated polyethylene glycol diacrylate or dimethacrylate (ethoxylated or methoxylated polyethylene glycol diacrylate or dimethacrylate); ethoxylated bisphenol A diacrylate (ethoxylated bisphenol A diacrylate), polyethylene glycol-polyethylene glycol urethane diacrylate (polyethylene glycol-polyethylene glycol urethane diacrylate), partially acrylated polyol oligomer (partially acrylated polyol oligomer) and polyester urethane diacrylate (polyester-based urethane diacrylates), for example sold under the trade name CNN 91.

Any other curable material may be considered, preferably a curable material having a Tg as defined herein when hardened.

In some of any of the embodiments described herein, the elastomeric formulation further comprises an initiator for initiating polymerization of the curable material.

When all of the curable materials (elastomeric and otherwise, if present) are photopolymerizable, a photoinitiator may be used in these embodiments.

Non-limiting examples of suitable photoinitiators include benzophenones (aromatic ketones), such as benzophenone, methylbenzophenone, michler's ketone, and xanthone; acyl phosphine oxide photoinitiators, e.g. 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide (2, 4,6-trimethylbenzolydiphenyl phosphine oxide, TMPO), 2,4, 6-trimethylbenzoyl ethoxy phenyl phosphine oxide (2, 4, 6-tr)imethylbenzoylethoxyphenyl phosphine oxide, TEPO) and bisacylphosphine oxides (bisacylphosphine oxides, BAPO's); benzoin (benzoins) and benzoin alkyl ethers (bezoin alkyl ethers), such as benzoin, benzoin methyl ether, benzoin isopropyl ether and the like. Examples of photoinitiators are alpha-amino ketones, bisacylphosphine oxides (bisacylphosphine oxides, BAPO's), and under the trade name And (5) selling the product.

A photoinitiator may be used alone or in combination with a co-initiator. Benzophenone is an example of a photoinitiator that requires a second molecule, such as an amine, to generate a radical. After radiation absorption, benzophenone reacts with a tertiary amine to form alpha-amino radicals through hydrogen abstraction, and polymerization of acrylic ester is initiated. Non-limiting examples of one class of co-initiators are alkanolamines such as triethylamine, methyldiethanolamine, and triethanolamine.

A concentration of a photoinitiator in a formulation comprising the photoinitiator may be from about 0.1 to about 5wt%, or from about 1 to about 5wt%, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the elastomeric formulation further comprises one or more additional non-curable materials, for example, one or more of a colorant, a dispersant, a surfactant, a stabilizer, and an inhibitor.

The formulation(s) include an inhibitor for preventing or slowing polymerization and/or curing prior to exposure to curing conditions. Conventional inhibitors, such as radical inhibitors, are contemplated.

Conventional surfactants, dispersants, colorants and stabilizers are contemplated. Exemplary concentrations of each component, if present, are in the range of about 0.01 to about 1, about 0.01 to about 0.5, or about 0.01 to about 0.1 weight percent of the total weight of the formulation containing the component.

In some embodiments of any of the embodiments described herein, the elastomeric material is an ultraviolet curable material, and in some embodiments, is an elastomeric (meth) acrylate, for example, an elastomeric acrylate.

In some embodiments of any of the embodiments described herein, an additional curable component is included in the elastomeric formulation, and in some embodiments, the component is an ultraviolet curable acrylate or methacrylate.

In some of any of the embodiments described herein, the silica particles are (meth) acrylate functionalized silica particles.

In some embodiments of any of the embodiments described herein, the elastomeric formulation comprises one or more monofunctional elastomeric acrylates, one or more multifunctional elastomeric acrylates, one or more monofunctional acrylates or methacrylates, and one or more multifunctional acrylates or methacrylates.

In some of these embodiments, the elastomeric formulation further comprises one or more photoinitiators, e.g.,a family.

In some of any of the embodiments described herein, all of the curable material and silica particles are included in a single formulation.

In some embodiments, the elastomeric formulation includes silica particles, one or more photoinitiators, and optionally other components.

In an exemplary formulation according to some of any of the embodiments described herein, all curable materials are (meth) acrylates.

In any of the exemplary formulations described herein, a concentration of a photoinitiator is in the range of about 1% to about 5%, about 2% to about 5%, about 3% to about 5%, or about 3% to about 4% by weight (e.g., 3, 3.1, 3.2, 3.25, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.85, 3.9, including any intermediate values therebetween) of the total weight of a formulation comprising the photoinitiator

In any of the exemplary formulations described herein, a concentration of an inhibitor is in the range of 0 to about 2%, or 0 to about 1% by weight of the total weight of a formulation comprising the inhibitor, and for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or about 1% by weight, including any intermediate values therebetween.

In any of the exemplary formulations described herein, a concentration of a surfactant is in the range of 0 to about 1% by weight, such as 0, 0.01, 0.05, 0.1, 0.5, or about 1% by weight, including any intermediate values therebetween, of the total weight of a formulation comprising the surfactant.

In any of the exemplary formulations described herein, a concentration of a dispersant is in the range of 0 to about 2% by weight of the total weight of a formulation comprising the dispersant, and for example, 0, 0.1, 0.5, 0.7, 1, 1.2, 1.3, 1.35, 1.4, 1.5, 1.7, 1.8, or about 2% by weight, including any intermediate values therebetween.

In exemplary formulations according to some of any of the embodiments described herein, a concentration of an elastomeric material is in the range of about 30% to about 90%, in the range of about 40% to about 90%, or in the range of about 40% to about 85% by weight.

In some embodiments, the elastomeric material includes a monofunctional elastomeric material and a multifunctional elastomeric material.

In some embodiments, a concentration of the monofunctional elastomeric material is in the range of about 20% to about 70%, or about 30% to about 50%, by weight, including any intermediate values and subranges therebetween. In exemplary embodiments, a concentration of the monofunctional elastomeric material is in the range of about 50% to about 70%, about 55% to about 65%, or about 55% to about 60% (e.g., 58%) by weight, including any intermediate values and subranges therebetween. In exemplary embodiments, a concentration of the monofunctional elastomeric material is in the range of about 30% to about 50%, about 35% to about 50%, or about 40% to about 45% (e.g., 42%) by weight, including any intermediate values and subranges therebetween.

In some embodiments, a concentration of the multifunctional elastomeric material is in the range of about 10% to about 30% by weight. In exemplary embodiments, a concentration of the monofunctional elastomeric material is in the range of about 10% to about 20%, or about 10% to about 15% (e.g., 12%) by weight. In exemplary embodiments, a concentration of the monofunctional elastomeric material is in the range of about 10% to about 30%, about 10% to about 20%, or about 15% to about 20% (e.g., 16%) by weight.

In exemplary formulations according to some of any of the embodiments described herein, a total concentration of an additional curable material is in the range of about 10% to about 40% by weight, or about 15% to about 35% by weight, including any intermediate values and subranges therebetween.

In some embodiments, the additional curable material comprises a monofunctional curable material.

In some embodiments, a concentration of the monofunctional additional curable material is in the range of about 15% to about 25%, or about 20% to about 25% (e.g., 21%) by weight, including any intermediate values and subranges therebetween. In exemplary embodiments, the concentration of the monofunctional elastomeric material is in the range of about 20% to about 30%, or about 25% to about 30% (e.g., 28%) by weight, including any intermediate values and subranges therebetween.

In exemplary formulations according to some of any of the embodiments described herein, the elastomeric material includes a monofunctional elastomeric material and a multifunctional elastomeric material; a concentration of the monofunctional elastomeric material is in the range of about 30% to about 50% (e.g., about 40% to about 45%), or in the range of about 50% to about 70% (e.g., about 55% to about 60%) by weight; and a concentration of the multifunctional elastomeric material in the range of about 10% to about 20% by weight; and the one or more formulations further comprise an additional monofunctional curable material in a total concentration in the range of about 20% to about 30% by weight.

According to some of any of the embodiments described herein, the elastomeric formulation comprises at least one elastomeric monofunctional curable material, at least one elastomeric multifunctional curable material, and at least one additional monofunctional curable material.

According to some of any of the embodiments described herein, a concentration of the curable monofunctional material is in the range of 10% to 30% by weight of the total weight of the elastomeric formulation.

According to some of any of the embodiments described herein, a concentration of the elastomeric monofunctional curable material is in the range of 50% to 70% by weight of the total weight of the elastomeric formulation.

According to some of any of the embodiments described herein, a concentration of the elastomeric multifunctional curable material is in the range of 10% to 20% by weight of the total weight of the elastomeric formulation.

According to some of any of the embodiments described herein, a concentration of the curable monofunctional material is in the range of 10% to 30% by weight of the total weight of the elastomeric formulation; a concentration of the elastomeric monofunctional curable material is in the range of 50% to 70% by weight of the total weight of the elastomeric formulation; and a concentration of the elastomeric multifunctional curable material is in the range of 10% to 20% by weight of the total weight of the elastomeric formulation.

According to some of any of the embodiments described herein, a concentration of the curable monofunctional material is in the range of 20% to 30% by weight of the total weight of the elastomeric formulation.

According to some of any of the embodiments described herein, a concentration of the elastomeric monofunctional curable material is in the range of 30% to 50% by weight of the total weight of the elastomeric formulation.

According to some of any of the embodiments described herein, a concentration of the elastomeric multifunctional curable material is in the range of 10% to 30% by weight of the total weight of the elastomeric formulation.

According to some of any of the embodiments described herein, a concentration of the curable monofunctional material is in the range of 20% to 30% by weight of the total weight of the elastomeric formulation; a concentration of the elastomeric monofunctional curable material is in the range of 30% to 50% by weight of the total weight of the elastomeric formulation; and a concentration of the elastomeric multifunctional curable material is in the range of 10% to 30% by weight of the total weight of the elastomeric formulation.

In some embodiments, an elastomeric formulation described herein is characterized by: when hardened, the tear strength is at least 4,000 newtons per meter (N/m), at least 4500N/m, or at least 5,000N/m.

In some embodiments, an elastomeric formulation described herein is characterized by: when hardened, the tear strength is at least 500N/m, at least 700N/m, or at least 800N/m higher than the tear strength of a formulation without the silica particles.

In some embodiments, an elastomeric formulation described herein is characterized by: when hardened, the tensile strength is at least 2MPa.

In some embodiments of any of the embodiments described herein, a kit is provided comprising an elastomeric formulation as described herein in any of the respective embodiments, and any combination thereof.

Throughout, the phrases "rubber," "rubber material," "elastomeric material," and "elastomer" are used interchangeably to describe materials having elastomeric properties. The phrase "rubber-like material" or "rubber-like material" is used to describe materials having rubber properties and is prepared by additive manufacturing (e.g., three-dimensional inkjet printing) rather than conventional processes involving vulcanization of thermoplastic polymers.

The term "rubber-like material" is also interchangeably referred to herein as "elastomeric material".

Elastomers or rubbers are flexible materials that are characterized by a low Tg (e.g., below room temperature, preferably below 10 ℃, below 0 ℃ and even below-10 ℃).

Some of the characteristics characterizing rubbery (elastomeric) materials used herein and in the art are described below.

Shore A Hardness (Shore A Hardness), also known as Shore Hardness or simply Hardness, describes the resistance of a material to permanent indentation, defined by the type A durometer scale. Shore hardness is typically measured according to ASTM D2240.

Elastic Modulus (Elastic Modulus), also known as Elastic Modulus (Modulus of Elasticity) or Young's Modulus, or Tensile Modulus (Tensile Modulus), or "E", describes the resistance of a material to Elastic deformation when a force is applied, or in other words, the tendency of an object to deform along an axis when opposing forces are applied along the axis. The modulus of elasticity is typically measured by a tensile test (e.g., according to ASTM D624) and is determined by the linear slope of a stress-strain curve in the elastic deformation region, where stress is the force causing the deformation divided by the area of force applied, and strain is the ratio of the change in some length parameter caused by the deformation to the original value of the length parameter. The stress is proportional to the tension on the material and the strain is proportional to the length of the material.

Tensile Strength (Tensile Strength) describes the Tensile Strength of a material, or in other words its ability to withstand loads tending to elongate, and is defined as the maximum stress (in MPa) applied during stretching before an elastomer composite breaks. Tensile strength is typically measured by a tensile test (e.g., according to ASTM D624) and is determined as the highest point of a stress-strain curve, as described herein and in the art.

Elongation (elongation) is the elongation (extension) of a uniform section of a material, expressed as a percentage of the original length, and is generally determined according to ASTM D412.

Z tensile elongation is the elongation measured as described herein when printed in the Z direction.

Tear resistance describes the maximum force required to tear a material, expressed in force units per unit length, where the force acts substantially parallel to the principal axis of the sample. Tear resistance may be measured by ASTM D412 method. ASTM D624 can be used to measure the ability to resist tearing (tear initiation) and to resist tear expansion (tear propagation). Typically, a sample is held between two holders and a uniform pulling force is applied until deformation occurs. The tear strength is then calculated by dividing the applied force by the thickness of the material.

Tear resistance at constant elongation describes the time required for a specimen to tear at constant elongation (below elongation at break).

Thus, throughout, the phrases "build material formulation," "uncured build material formulation," "build material," and other variations collectively describe a material that is dispensed to sequentially form multiple layers, as described herein. This phrase includes uncured material, i.e., one or more uncured modeling material formulations, that are dispensed to form an object, and uncured material, i.e., uncured support material formulations, that are dispensed to form a support.

Throughout, the phrase "cured modeling material" or "hardened modeling material" describes that when a dispensed build material is exposed to cure, and optionally if a support material is dispensed, portions of the build material of an object as defined herein are formed as well when the cured support material is removed. The cured modeling material may be a single curing material or a mixture of two or more curing materials, depending on the modeling material formulation used in the methods described herein.

The phrase "cured modeling material" or "cured modeling material formulation" may be considered a cured build material, wherein the build material consists of only the modeling material formulation and not the support material formulation. That is, this phrase refers to the portion of the build material that is used to provide the final object.

Throughout, the phrase "modeling material formulation (modeling material formulation)", also interchangeably referred to herein as "modeling formulation (modeling formulation)", "modeling formulation (model formulation)", "modeling material formulation (model material formulation)", or simply "formulation)", describes part or all of the build material being dispensed to form an object. The modeling material formulation is an uncured modeling formulation (unless specifically stated otherwise) that forms an object or portion thereof when exposed to curing energy.

In some embodiments of the present invention, a model material formulation for three-dimensional inkjet printing is formulated and is capable of forming a three-dimensional object on its own, i.e., without mixing or combining with any other substance.

An uncured build material may include one or more mold formulations and may be dispensed such that, upon curing, different portions of the object are made from different cured mold formulations or different combinations thereof and, therefore, from different cured mold materials or different mixtures of cured mold materials.

The build material-forming formulation (model material formulation and support material formulation) includes one or more curable materials that form a hardened (cured) material when exposed to curing energy.

Throughout, a "curable material" is a compound (typically a monomeric or oligomeric compound, and optionally also a polymeric material) that cures or hardens when exposed to curing energy, as described herein, to form a cured material. The curable material is typically a polymerizable material that polymerizes and/or crosslinks when exposed to a suitable energy source.

The polymerization may be, for example, free radical polymerization, cationic polymerization, or anionic polymerization, and each may be initiated upon exposure to curing energy, such as radiation, heat, or the like, as described herein.

In some of any of the embodiments described herein, a curable material is a photopolymerizable material that polymerizes and/or crosslinks upon exposure to radiation, as described herein, and in some embodiments, the curable material is an ultraviolet curable material that polymerizes and/or crosslinks upon exposure to ultraviolet radiation, as described herein.

In some embodiments, the curable material described herein is a photopolymerizable material that is polymerized by photo-induced free radical polymerization. Alternatively, the curable material is a photopolymerizable material that is polymerized by photo-cationic polymerization.

In some of any of the embodiments described herein, a curable material may be a monomer, an oligomer, or a short chain polymer, each being polymerizable and/or crosslinkable as described herein.

In some of any of the embodiments described herein, a curable material hardens (cures) by any one or a combination of chain extension and crosslinking when exposed to curing energy (e.g., radiation).

In some of any of the embodiments described herein, a curable material is a monomer or a mixture of monomers that, when exposed to curing energy at which polymerization occurs, can form a polymeric material upon polymerization. Such curable materials are also referred to herein as monomeric curable materials.

In some of any of the embodiments described herein, a curable material is an oligomer or a mixture of oligomers that, when exposed to curing energy at which polymerization occurs, can form a polymeric material upon polymerization. Such curable materials are also referred to herein as oligomer curable materials.

In some of any of the embodiments described herein, a curable material, whether monomeric or oligomeric, may be a monofunctional curable material or a polyfunctional curable material.

Herein, a monofunctional curable material comprises one functional group that is polymerizable upon exposure to curing energy (e.g., radiation).

A multifunctional curable material comprises two or more, for example 2, 3, 4 or more, functional groups that polymerize when exposed to curing energy. The multifunctional curable material may be, for example, a difunctional, trifunctional or tetrafunctional curable material, which contains 2, 3, or 4 groups, respectively, that are polymerizable. Two or more functional groups in the multifunctional curable material are typically linked to each other by a linking moiety as defined herein. When the linking moiety is part of an oligomer or polymer, the multifunctional group is an oligomer or polymer multifunctional curable material. The multifunctional curable material may polymerize when subjected to curing energy and/or as a cross-linking agent.

According to some embodiments of the invention, the intermediate structure has a thickness of about 100 μm to about 300 μm, more preferably about 210 μm to about 290 μm, still more preferably about 220 μm to about 280 μm, for example about 250 μm.

According to some embodiments of the invention, the sacrificial structure is characterized by a tear resistance after curing of at least 4 kilonewtons per meter (kN) when measured according to international standard ASTM D-624 after curing.

According to some embodiments of the invention, the sacrificial structure is characterized by a tear resistance after curing of the sacrificial structure of from about 4kN per meter to about 8kN per meter, more preferably from about 5kN per meter to about 7kN per meter, when measured according to international standard ASTM D-624.

According to some embodiments of the invention, the peel force is about 1N to about 20N, for example about 10N.

According to some embodiments of the invention, a thickness of the sacrificial structure is selected such that a peel force of about 5N results in a bending strain of at least 0.02, more preferably at least 0.022, more preferably 0.024, more preferably 0.026.

According to some embodiments of the invention, the peel force is about 1N to about 10N, for example about 5N.

According to some embodiments of the invention, the sacrificial structure has a minimum thickness of about 500 μm to about 3 millimeters (mm), more preferably about 500 μm to about 2.5mm, and even more preferably about 500 μm to about 2mm.

According to some embodiments of the invention, for at least one of the stack of model layers and the layered sacrificial structure, the model material has a flexural modulus of about 2000MPa to about 4000MPa, more preferably about 2000MPa to about 3500MPa, about 2200MPa to about 3200MPa, when measured according to international standard ASTM D-790-04.

According to some embodiments of the invention, the flexible material is selected from the group consisting of monofunctional elastomer monomers, monofunctional elastomer oligomers, multifunctional elastomer monomers, multifunctional elastomer oligomers, and any combination thereof.

According to some embodiments of the invention, the formulation further comprises at least one additional curable material.

According to some embodiments of the invention, the additional curable material is selected from a monofunctional curable monomer, a monofunctional curable oligomer, a multifunctional curable monomer, a multifunctional curable oligomer, and any combination thereof.

According to some embodiments of the invention, the at least one modeling material formulation further comprises at least one additional non-curable material, such as a colorant, an initiator, a dispersant, a surfactant, a stabilizer, and an inhibitor.

According to some embodiments of the invention, the flexible material is an ultraviolet curable elastomeric material.

According to some embodiments of the invention, the flexible material is an acrylic elastomer.

According to some embodiments of the invention, the formulation is characterized by a tear resistance at hardening at least 0.5 kN/m higher than a cured formulation having the same elastomeric material but without silica particles.

According to some embodiments of the invention, the formulation comprises at least one elastomeric monofunctional curable material, at least one elastomeric multifunctional curable material, and at least one additional monofunctional curable material.

According to some embodiments of the invention, the curable monofunctional material has a total concentration in the range of 10 to 30% by weight of the total weight of the formulation.

According to some embodiments of the invention, the total concentration of the elastomeric monofunctional curable material is in the range of 50% to 70% by weight of the total weight of the formulation.

According to some embodiments of the invention, the total concentration of the elastomeric multifunctional curable material is in the range of 10% to 20% by weight of the total weight of the formulation.

According to some embodiments of the invention, the curable monofunctional material has a total concentration in the range of 10% to 30% by weight of the total weight of the formulation; a total concentration of elastomeric monofunctional curable material in the range of 50% to 70% by weight of the total weight of the formulation; and a total concentration of elastomeric multifunctional curable material is in the range of 10% to 20% by weight of the total weight of the formulation.

According to some embodiments of the invention, the curable monofunctional material has a total concentration in the range of 20% to 30% by weight of the total weight of the formulation.

According to some embodiments of the invention, the total concentration of the elastomeric monofunctional curable material is in the range of 30% to 50% by weight of the total weight of the formulation.

According to some embodiments of the invention, the total concentration of the elastomeric multifunctional curable material is in the range of 10% to 30% by weight of the total weight of the formulation.

According to some embodiments of the invention, the curable monofunctional material has a total concentration in the range of 20% to 30% by weight of the total weight of the formulation; a total concentration of elastomeric monofunctional curable material in the range of 30% to 50% by weight of the total weight of the formulation; and a total concentration of elastomeric multifunctional curable material is in the range of 10% to 30% by weight of the total weight of the formulation.

It is expected that during the life of a patent expiring this application many build materials will be developed that are relevant to additive manufacturing and the scope of the terms "modeling material" and "support material" is intended to include in advance all such new technologies.

The colors of the different materials mentioned herein are expressed as follows: cyan (C), magenta (M), yellow (Y), white (W), black (K). The support material may be denoted as (S). The clear/transparent material may be denoted as (T). Multiple materials may be referred to in series as, for example: CMY, CMYWKS, and the like.

As used herein, the term "about" refers to about ± 10%.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments.

The word "optionally" is used herein to mean "provided in some embodiments, but not in other embodiments". Any particular embodiment of the invention may include a plurality of "optional" features unless these contradict.

The terms "include," comprising, "" including, "and variations thereof mean" including but not limited to.

The term "consisting of" means "including and limited to".

The term "consisting essentially of" (consisting essentially of) means that the composition, method, or structure can include additional ingredients, steps, and/or components, but only if the additional ingredients, steps, and/or components do not materially alter the basic and novel characteristics of the claimed composition, method, or structure.

As used herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

As used herein, the term "about" refers to about ± 10%.

Throughout this application, various embodiments of the invention may be presented in a range of forms. It should be understood that the description of the range format is merely for convenience and brevity and should not be construed as a limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all possible sub-ranges and individual values within the range. For example, a description of a range from 1 to 6 should be considered to have explicitly disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, and the like, as well as individual values within the range, e.g., 1, 2, 3, 4, 5, and 6. The width of the range is applicable.

Whenever a numerical range is referred to herein, it is intended to include any reference number (fractional or integer) within the indicated range. The phrases "a range between a first indicator number and a second indicator number" and "a range from a first indicator number to a second indicator number" are used interchangeably herein and are intended to include both the first and second indicator numbers and all fractions and integers therebetween.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as appropriate in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered as essential features of those embodiments unless the described embodiments are not functional without those elements.

As described herein, various embodiments and aspects of the invention are experimentally supported in the following examples.

Example

Reference is now made to the following examples, which together with the above description illustrate some embodiments of the invention in a non-limiting manner.

Example 1

Proof of concept

Experiments were performed to determine parameters suitable to ensure removal of the sacrificial structures by lift-off.

One object being manufactured is a color cat owl statue.

Fig. 14A, 14B, 14C and 14D are images showing the process of peeling a flexible sacrificial structure from a color cat owl statue. The sacrificial structure is formed of a flexible black material. Alternatively, the flexible sacrificial structure may be formed with a thin spacer layer of soft material between it and the object being formed.

Example 2

Shore A (Shore A) experiment

In some embodiments of the present invention, when a black flexible material is used in place of the black mold material to form a peelable sacrificial structure, the area of the object containing a substantial amount of flexible black material may have reduced physical properties, such as a significant decrease in its Shore A value. To solve this problem, two main solutions are envisaged: (1) Printing black areas using a digital Combination (CMY) of colored model materials to obtain black and avoid variations in physical properties; or (2) a black flexible material is used in combination with a proportion of color CMY materials so that physical properties are not degraded. Although scheme (1) may be suitable in some cases, it also has some drawbacks in that it is difficult to obtain a "pure black" color using only a mixture of CMY colors, and consumption of CMY model materials increases. For the second approach, experiments were performed to determine the minimum amount of modeling material required for use in combination with the flexible material to avoid a reduction in the shore a value.

A Shore durometer Zwick 3110..13 (Zwick/Roell, germany) was used according to Standard test method ASTM D2240, at a J750 Polyjet ^TM Printer @The shore a value was measured on a 20 x 7mm black sample printed on israel, inc.). Using a solution from Vero ^TM Series (/ ->Available from israel), selected from the group consisting of tangobackplus ^TM FLX 980(/>Available from israel, israel) and Agilus30 ^TM Black FLX985(/>Company, israel) tested for various combinations of numbers. When printing a sample, droplets of flexible material may be randomly deposited to obtain a uniform structure. The results obtained are shown in fig. 15 and table 1 below.

TABLE 1

Model [%]	Agilus[％]	Shore A	Tango+[％]	Shore A
					0	100	21	100	20
5	95	35	95	30
					9	91	48	91	42
14	86	49	86	50
					17	83	59	83	60
22	78	63	78	65
					25	75	70	75	72
29	71	75	71	76
					32	68	80	68	80
36	64	80	64	80
					38	62	80	62	80
42	58	80	58	80
					45	55	80	55	80
47	53	80	53	80
					50	50	80	50	80
59	41	80	41	80
					100	0	80	0	80

The above experiments show that if the sample comprises at least about 30% of the model material in combination with a flexible material (up to 70%) randomly distributed between the structures of the sample, the shore a value of the sample is similar to the shore a value measured for a sample comprising 100% of the model material, but no change in physical properties is observed.

Example 3

Viscosity test

In some embodiments of the present invention, when a black flexible material is used in place of the black mold material so that a peelable sacrificial structure can be formed, the area containing the bulk of the black object tends to be tacky due to the chemical composition of the flexible material. To solve the "sticky" problem, two main solutions are envisaged: (1) Printing black areas using a combination of colored model materials (CMY), digitally simulating black and avoiding a sticky effect; or (2) a black flexible material is used in combination with a proportion of colored CMY material until little tackiness is found. Although scheme (1) may be appropriate in some cases, it also has some drawbacks in that it is difficult to create a "pure black" color by simply mixing CMY colors, and the consumption of CMY model material increases. With respect to the second option, experiments were conducted to determine the minimum amount of model material required to be used in combination with the flexible material to make the viscous effect negligible.

Tack values were measured using an LR30K Lloyd instrument (Ametek, usa). Print a circular probe on a J750 PolyJettm printerA company, israel) 60 x 6mm black sample contact and exert a force of about 400N. The probe is slowly pulled out of the sample while measuring the force value over time. The area under the curve is integrated to obtain a "tack" value in N mm. Use of the sequence from VeroTM (+.>Model material from Limited, israel) and selected from TangoBlackPlusTM FLX 980 (Israel)>Limited, israel) and Agilus30 (TM) Black FLX985 (+.>Company, israel) to test various combinations of numbers. When printing a sample, droplets of flexible material may be randomly deposited to obtain a uniform structure. The results obtained are shown in fig. 16 and in table 2 below.

TABLE 2

The above experiments show that if the sample comprises a combination of at least about 30% of the model material and a flexible material (up to 70%) randomly distributed between the sample structures, the viscous effect is negligible.

While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

All publications, patents, and patent applications mentioned in this specification are herein incorporated in their entirety by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. The section headings are not to be construed as necessarily limiting.

Claims

1. A method of additive manufacturing of a three-dimensional object, the method comprising:

sequentially dispensing and curing a plurality of layers, wherein the plurality of layers are formed from: (i) A plurality of differently colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) A black flexible material arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object, the flexible material being an ultraviolet curable elastomeric material; and (iii) a soft material arranged in a configuration pattern to provide separation between the model material and the sacrificial structure;

Wherein the plurality of differently colored mold materials does not include a black mold material and the black flexible material is applied to form a first portion of the object defined as black.

2. The method according to claim 1, characterized in that: a second portion of the object defined as black is formed based on digitally mixing the plurality of differently colored model materials to create a black color.

3. The method according to claim 2, characterized in that: the second portion of the object is greater than a defined threshold and the first portion of the object is less than the defined threshold.

4. A method according to any one of claims 1 to 3, characterized in that: the soft material is arranged in a configuration pattern to form a plurality of spaces in the sacrificial structure.

5. The method according to claim 4, wherein: the plurality of spaces are formed on a plurality of symmetrical planes with respect to the object.

6. A method according to any one of claims 1 to 3, characterized in that: the soft material is configured to fill a plurality of holes defined by a geometry of the object.

7. A method according to any one of claims 1 to 3, characterized in that: the soft material is configured to include a plurality of fine features that are prone to fracture when a tensile or peeling force is applied in the vicinity of the plurality of fine features.

8. A method according to any one of claims 1 to 3, characterized in that: a thickness of the separation between the modeling material and the sacrificial structure provided by the soft material is 100 microns to 300 microns.

9. A method according to any one of claims 1 to 3, characterized in that: a minimum thickness of the sacrificial structure is X1 to X2, where X1 is 450 micrometers to 550 micrometers and X2 is 2.7 millimeters to 3.3 millimeters.

10. A method according to any one of claims 1 to 3, characterized in that: at least a portion of the mold material has a flexural modulus of 2000 megapascals to 4000 megapascals.

11. A method according to any one of claims 1 to 3, characterized in that: the modeling material comprises at least one additional non-curable material, wherein the non-curable material is selected from the group consisting of: a colorant, an initiator, a dispersant, a surfactant, a stabilizer and an inhibitor.

12. A method according to any one of claims 1 to 3, characterized in that: the sacrificial structure is characterized in that: the sacrificial structure has a tear resistance after curing of at least 4 kilonewtons per meter when measured according to international standard ASTM D-624 after curing.

13. A method according to any one of claims 1 to 3, characterized in that: the sacrificial structure is characterized in that: the sacrificial structure has a tear resistance after curing of from X1 to X2, where X1 is from 3.6 kilonewtons per meter to 4.4 kilonewtons per meter and X2 is from 7.2 kilonewtons per meter to 8.8 kilonewtons per meter when measured according to international standard ASTM D-624.

14. A method according to any one of claims 1 to 3, characterized in that: the sacrificial structure is configured to be peeled by applying a peeling force, and wherein a magnitude of the peeling force is from X1 to X2, wherein X1 is 0.9 newton to 1.1 newton and X2 is 18 newton to 22 newton.

15. The method according to claim 14, wherein: the sacrificial structure is configured such that the peel force of 5 newtons results in a bending strain of at least 0.02.

16. A method according to any one of claims 1 to 3, characterized in that: the flexible material is a formulation comprising a plurality of silica particles.

17. The method according to claim 16, wherein: the preparation is characterized in that: a tear resistance upon hardening is at least 0.5 kilonewtons per meter higher than a cured formulation having the same flexible material but without the plurality of silica particles.

18. The method according to claim 16, wherein: an average particle size of the plurality of silica particles is less than 1 micron.

19. The method according to claim 16, wherein: at least a portion of the plurality of silica particles includes a hydrophilic surface.

20. The method according to claim 16, wherein: at least a portion of the plurality of silica particles includes a hydrophobic surface.

21. The method according to claim 16, wherein: at least a portion of the plurality of silica particles comprises a plurality of functionalized silica particles.

22. The method according to claim 21, wherein: at least a portion of the plurality of silica particles are functionalized with a plurality of curable functional groups.

23. The method as claimed in claim 22, wherein: the plurality of curable functional groups includes a plurality of (meth) acrylate groups.

24. The method according to claim 16, wherein: a content of the plurality of silica particles in the formulation ranges from 1 to 20 wt%, from 1 to 15 wt%, or from 1 to 10 wt% of the total weight of the formulation.

25. The method according to claim 16, wherein: a weight ratio of the flexible material to the plurality of silica particles ranging from 30:1 to 4:1.

26. the method according to claim 16, wherein: the flexible material is present in an amount of at least 40% or at most 50% of the total weight of the formulation.

27. The method according to claim 16, wherein: the flexible material comprises one or more of the following materials: a monofunctional elastomer monomer, a monofunctional elastomer oligomer, a multifunctional elastomer monomer, and a multifunctional elastomer oligomer.

28. The method according to claim 16, wherein: the formulation includes an additional curable material.

29. The method according to claim 16, wherein: the formulation includes an elastomeric monofunctional curable material, an elastomeric polyfunctional curable material, and an additional monofunctional curable material.

30. The method according to claim 29, wherein: a concentration of the elastomeric monofunctional curable material ranges from 10% to 30% by weight.

31. The method according to claim 29 or 30, characterized in that: a concentration of the elastomeric monofunctional curable material ranges from 50% to 70% by weight.

32. The method according to claim 29, wherein: a concentration of the elastomeric multifunctional curable material ranging from 10% to 20% by weight; 20% to 30% by weight; 30% to 50% by weight; or 10% to 30% by weight.

33. A method according to any one of claims 1 to 3, characterized in that: the flexible material is peelable and has a flexural modulus of from 2000 mpa to 4000 mpa.

34. The method according to claim 33, wherein: the flexible material is an acrylic elastomer.

35. A computer readable medium storing a plurality of instructions that, when read by a computer controller of an additive manufacturing system, cause the system to sequentially dispense and cure layers of an object formed of: (i) A plurality of differently colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) A flexible material arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) a soft material arranged in a configuration pattern to provide separation between the mold material and the sacrificial structure, wherein the plurality of differently colored mold materials does not include a black mold material, the soft material is black, and the plurality of instructions includes a plurality of commands to apply the soft material in black to form a first portion of the object defined as black, and a plurality of commands to create black in a second portion of the object by digitally mixing the plurality of colored mold materials.

36. An additive manufacturing system for manufacturing a three-dimensional, colored object, the additive manufacturing system comprising:

a building material supply apparatus configured to house a set of supply boxes, wherein the set of supply boxes comprises: a set of cartridges having different colored modeling materials; a case comprising a flexible material; and a case comprising a soft material having a modulus of elasticity less than a modulus of elasticity of the soft material;

a plurality of nozzle arrays mounted in a plurality of dispensing heads configured to receive a plurality of materials from the build material supply apparatus;

a curing system configured to cure the plurality of materials dispensed from the plurality of dispensing heads; and

a computer controller having a circuit configured for operating the plurality of dispensing heads and the curing system to sequentially dispense and cure a plurality of layers comprising: (i) A plurality of differently colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) The flexible material being arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) the soft material arranged in a configuration pattern to provide separation between the mold material and the sacrificial structure, wherein the plurality of different colored mold materials do not include a black mold material, the soft material is black, and the plurality of dispensing heads are configured to operate to print a first portion of the object defined as black by dispensing the black flexible material, and to print a second portion of the object defined as black by digitally mixing the plurality of colored mold materials to create black.

37. An additive manufacturing system for manufacturing a three-dimensional object, the additive manufacturing system comprising:

a building material supply apparatus configured to accommodate a maximum of six supply cartridges, wherein the plurality of supply cartridges is selected from a group comprising: a plurality of cartridges having different colored modeling materials; a plurality of cartridges having a flexible material; and a plurality of cartridges having a soft material, wherein a modulus of elasticity of the soft material is less than a modulus of elasticity of the soft material;

a maximum of six nozzle arrays mounted in a plurality of dispensing heads configured to receive a plurality of materials from the build material supply apparatus;

a computer controller having a circuit configured for operating the plurality of dispensing heads and the curing system to sequentially dispense and cure a plurality of layers comprising: (i) A plurality of differently colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) The flexible material being arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) the soft material arranged in a configuration pattern to provide separation between the model material and the sacrificial structure;

Wherein the plurality of different colored modeling materials does not include black modeling material, the flexible material is black, and the plurality of dispensing heads are configured to be operated to print a first portion of the object defined as black by dispensing the flexible material in black, and to print a second portion of the object defined as black by digitally mixing the plurality of colored modeling materials to create black.

38. A system for manufacturing a three-dimensional object by additive manufacturing, the system comprising:

a building material supply apparatus configured to accommodate a maximum of six supply cartridges, wherein the plurality of supply cartridges is selected from a group comprising: a plurality of cartridges having a plurality of different colored modeling materials; a plurality of cartridges having a black flexible material; and a plurality of cartridges having soft materials, wherein a modulus of elasticity of the soft materials is less than a modulus of elasticity of the soft materials, and wherein the plurality of differently colored model materials include white, cyan, magenta, and yellow;

a maximum of three dispensing heads configured to receive a plurality of materials from the build material supply apparatus;

A curing system configured to cure each of the plurality of materials; and

a computer controller having a circuit configured for operating the plurality of dispensing heads and the curing system to sequentially dispense and cure a plurality of layers comprising: (i) The plurality of different colored modeling materials arranged in a configuration pattern corresponding to a shape and color definition of the object; (ii) The flexible material being arranged in a configuration pattern to form a sacrificial structure at least partially surrounding the object; and (iii) the soft material arranged in a configuration pattern to provide separation between the model material and the sacrificial structure;

wherein the plurality of differently colored modeling materials does not include a black modeling material, wherein at least a portion of the at most three dispensing heads are configured to be operated to print a first portion of the object defined as black by dispensing the flexible material in black, and to print a second portion of the object defined as black by digitally mixing cyan, magenta, and yellow to create black in the object.

39. The system according to any one of claims 36 to 38, wherein: the flexible material is black, and wherein the flexible material is applied to form at least a portion of the object defined as black.

40. The system according to claim 39, wherein: if the volume of the black portion is greater than a defined threshold, a black portion of the object is formed based on a digital mix of the different colored model materials; and if the volume of the black portion is less than the defined threshold, the black portion is made of the flexible material.

41. The system according to any one of claims 36 to 38, wherein: the soft material is arranged in a configuration pattern to form a plurality of spaces in the sacrificial structure.

42. The system according to any one of claims 36 to 38, wherein: the soft material is configured to fill a plurality of holes defined by a geometry of the object.

43. The system according to any one of claims 36 to 38, wherein: a thickness of the separation between the modeling material and the sacrificial structure provided by the soft material is 100 microns to 300 microns.

44. The system according to any one of claims 36 to 38, wherein: a minimum thickness of the sacrificial structure is from 500 microns to 3 millimeters.