CN106893306B - A kind of polyurethane 3D printing material of low melting point and preparation method thereof - Google Patents

Abstract

The invention discloses polyurethane 3D printing materials of a kind of low melting point and preparation method thereof, its main feature is that component raw material and proportion (molfraction) are as follows: 80-120 parts of 80-150 parts of polyalcohol, diisocyanate, end group containing furan nucleus are 0.1-5 parts of 1-20 parts of diisocyanate compositions, the dendritic of maleimide.Contain dynamic chemical key Diels-Alder key in the molecular structure of polyurethane material, polyurethane 3D printing material melt temp produced by the present invention is low, print procedure is smooth, free from extraneous odour, and product surface is bright and clean, dimensionally stable, is not easy to shrink.

Description

A kind of low melting point polyurethane 3D printing material and preparation method thereof

technical field

The invention relates to the field of polyurethane 3D printing materials, in particular to a polyurethane 3D printing material with a low melting point and a preparation method thereof.

Background technique

Rapid prototyping technology is a technology that uses a computer to establish a three-dimensional model of an object, and based on this technology, it is a technology that is directly formed. Compared with traditional forming technology, it significantly shortens the research and development cycle of new products and reduces the cost of research and development. There are many kinds of rapid prototyping methods, such as laser sintering, laser melting, fused deposition, 3D printing, three-dimensional photolithography and so on. The basic working principle of rapid prototyping technology is modeling, stacking and rapid prototyping. Firstly, the physical shape of the object is converted into a three-dimensional digital solid model through modeling software or a three-dimensional scanner, and then the materials are piled up layer by layer by using the above method. To process and solidify to obtain the required shaped parts, rapid prototyping technology has been widely used in developed countries.

3D printing technology is a kind of rapid prototyping technology. Its working principle is similar to inkjet printing, that is, it responds to the digital signal of the computer, so that the molten material or binder in the working cavity of the nozzle forms liquid droplets in an instant, and the liquid droplets are formed in a certain amount. The speed is extruded from the nozzle and sprayed onto the support model to form the shape of the outline. After the thin layer is solidified, it continues to be sprayed and piled up layer by layer to obtain a high-precision formed part. 3D printing technology does not require expensive laser equipment, so the equipment is cheap, and the operation and maintenance costs are very low. Moreover, 3D printing technology has the characteristics of simple operation, fast forming speed, and no pollution during the forming process.

According to the different injection molding materials, 3D printing technology can be divided into three types: adhesive-powder 3D printing, light-curing resin 3D printing and fusion 3D printing. Adhesive-powder 3D printing is to spray liquid adhesive to the powder material layer, and then bond and form layer by layer; photocurable resin 3D printing uses liquid photosensitive resin for spraying and ultraviolet light for curing and forming. Fusion 3D printing transfers polymer materials to a high-temperature heat source for melting, and then continuously extrudes molten polymers to accumulate molded parts layer by layer. The post-processing process is simple. 3D Systems has developed a 3D printer that sprays thermoplastics.

There are currently few types of polymer materials that can be used for 3D printing. The reported ones are mainly acrylonitrile-butadiene-styrene terpolymer (ABS) and polylactic acid (PLA). The two-phase inhomogeneous structure of the graft copolymer with chain and the graft copolymer with resin as the main chain makes it have the high chemical stability, oil resistance and surface hardness of acrylonitrile, and the toughness and cold resistance of butadiene Good dielectric properties, gloss and processability of styrene and other comprehensive properties. However, its strength is not high, and as the molecular weight increases, the processing performance decreases; and ABS has an odor during the printing process, the molded product is easy to shrink, and the dimensional stability of the printed product is not good. However, PLA has poor mechanical properties and is prone to brittle fracture, which limits its processing performance. Therefore, the development of new functional polymer materials for 3D printing is of great significance to make up for the shortcomings that restrict the rapid development of the 3D printing field.

Polyurethane elastomer is a new type of organic polymer synthetic material, which has excellent wear resistance, excellent ozone resistance, high hardness, high strength, good elasticity, low temperature resistance, good oil resistance, chemical resistance and environmental resistance. , and non-toxic and tasteless, so its market and application fields continue to expand and develop rapidly. Lanbijian disclosed a polyurethane material that can be used for 3D printing in patent 201410425030.7. In this method, toluene diisocyanate is mixed with acetone, tetraethylammonium bromide is added, and azobisisobutylamidine hydrochloride is added in sequence after stirring at room temperature Salt, 3-aminopropyltrimethoxysilane, polyurethane particles, and finally heated and stirred to obtain a polyurethane composite material. Sichuan University disclosed a polyurethane composite material for 3D printing and its preparation method and application in patent 201510298936.1. The polyurethane composite material is composed of 100 parts of polyurethane, 0.1-10 parts of inorganic filler, 0.1-0.5 part of light stabilizer, and 0.1-0.5 part of antioxidant, and the average particle size of the obtained polyurethane composite material powder is 10-100 μm, which has good Flexibility and the introduction of inorganic fillers improve the 3D printing performance of polyurethane, and at the same time make the product have excellent mechanical properties, its tensile strength can reach 20.12Mpa, and the elongation at break can reach 511.12%. Shanghai Materials Research Institute discloses a thermoplastic polyurethane modified composite material for FDM 3D printing and its preparation method in patent 201510278792.3. It is prepared by using the following components and raw materials in parts by weight: thermoplastic polyurethane 70-95, antioxidant 1-5, anti-hydrolysis stabilizer 1-5, compatibilizer 1-5, lubricant 1-5, other additives 1-10. Zibo Zhengda Energy Saving New Material Co., Ltd. discloses a polyurethane material for 3D printing in patent 201410803193.4, which is composed of 25-80 parts of polyether polyol, 1-4.5 parts of catalyst, and 2-10 parts of polyisocyanate; Solid consumables are easy to plug, inconvenient to install, high cost, need to be dyed later, unstable performance and other problems. Shanghai Hengan Polyurethane Co., Ltd. disclosed a 3D printing thermoplastic polyurethane material and its preparation method in patent 201510979494.7. Its composition by weight consists of 35-75 parts of macromolecular polyols, 0-10 parts of fluorine-containing polyols, small molecule chain extension 2-25 parts of agent, 0-7 parts of fluorine-containing chain extender, 5-60 parts of isocyanate, 0-8 parts of hydrolysis stabilizer, and 0-10 parts of other additives. The preparation method adopts an in-situ polymerization one-step method to introduce fluorine element into the thermoplastic polyurethane material, and prepares a 3D printing thermoplastic polyurethane material which has both the advantages of fluorine-containing compounds and TPU.

Reducing the melting temperature of the polyurethane material helps to avoid the thermal degradation of the polyurethane material caused by the high temperature of the 3D printing process. Since the D-A bond has a thermally reversible function, it is possible to use the characteristics of the D-A reaction to construct the D-A bond in the polyurethane molecular structure. Minimize the melting temperature of polyurethane materials. Sichuan University once disclosed in the patent 201510299301.3 a polyurethane material containing dynamic bonds for 3D printing and its preparation method and application. 75 parts, 50-125 parts of diol chain extender containing Diels-Alder bond, 0-50 parts of diisocyanate trimer crosslinking agent, 50-100 parts of diol chain extender containing ligand, metal salt The cross-linking agent is 0-50 parts, and the prepared polyurethane material has the function of self-repair and self-bonding. The main feature of this patent is to use a diol containing a Diels-Alder bond as a chain extender or a diol containing a ligand as a chain extender to form a polyurethane 3D printing material with a main chain containing a D-A bond, but The polyurethane material containing Diels-Alder bonds in this patent has a linear structure. Compared with polyurethane with a body structure, its mechanical properties are much inferior. The performance of polymer materials is a concrete reflection of its internal structure and molecular motion, and the structural characteristics of polymer materials have a great influence on the performance of polymer materials. Similarly, the type, quantity, position, and structural characteristics of the D-A bond in the molecular structure of polyurethane also have a great impact on the properties of polyurethane materials for 3D printing. Searching a large number of patent documents and published research papers has not found that the use of furan rings Polyols and maleimide-terminated isocyanate compositions are used as cross-linking agents to construct low-melting polyurethane materials for 3D printing.

Contents of the invention

The purpose of the present invention is to provide a polyurethane 3D printing material with a low melting point and its preparation method in order to avoid thermal degradation of the polyurethane 3D printing material. , when the temperature rises to the critical temperature, the Diels-Alder dynamic bond breaks and cross-links, and the viscosity of the system decreases rapidly, which reduces the melting temperature of the polyurethane material, which is conducive to extrusion printing; when the temperature decreases, the Diels-Alder dynamic bond is re-formed , to crosslink the system and enhance the mechanical properties of the product.

The purpose of the present invention can be achieved through the following technical solutions:

A polyurethane 3D printing material with a low melting point, using the following components and raw material ratios, wherein the parts of raw materials are molar parts unless otherwise specified;

Component raw materials and ratio:

Wherein the mole fraction of polyhydric alcohol containing furan ring/the mole fraction of diisocyanate≥1.

A method for preparing a low melting point polyurethane 3D printing material, comprising the following steps:

Weigh 80-150 parts of polyols containing furan rings, 80-120 parts of diisocyanates, 1-20 parts of diisocyanate compositions whose end groups are maleimides, and 0.1-5 parts of dendrimers, and place them in After melting and dehydration at 30-150°C for 2-4 hours; at the same time, put it into a twin-screw reaction extruder for reaction, and obtain polyurethane particles through underwater pelletizing, and place the obtained polyurethane particles in an oven at 60-200°C to dry and mature for 4 hours. -72h, get the required polyurethane 3D printing material. Control the temperature of each section of the screw extruder as follows: 90-120°C, 120-140°C, 140-150°C, 150-160°C, 160-180°C, 90-120°C.

The isocyanate is diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, dimethyl biphenyl diisocyanate, hexamethylene One or more combinations of diisocyanates;

The composition and preparation method of the furan ring-containing polyol is as follows: 100 parts of organic dicarboxylic acid, 50-100 parts of diol, 5-50 parts of 2,5-dimethylolfuran, 0 parts of titanate catalyst - 1 part is put into the reactor for melting, nitrogen gas is introduced, and the reaction is carried out at 170-230° C. for 5-72 hours until the acid value is less than 0.5 mgKOH/g to obtain furan ring-containing polyols.

The composition and preparation method of the diisocyanate composition whose terminal group is maleimide is as follows: under the condition of N2 protection and mechanical stirring, fully mix 100 parts of diisocyanate and 100-200 parts of organic solvent, and add Add 200-210 parts of N-hydroxyethylmaleimide within 30 minutes, react in an ice-water bath for 2 hours, then continue to react for 0.5-1 hour at room temperature, and then evaporate the organic solvent to obtain maleic acid at both ends. Diisocyanate compositions of imines. Described organic solvent is dimethyl formamide, ethyl acetate, tetrahydrofuran, anhydrous ether, sherwood oil, toluene, acetone, methylene chloride, chloroform, dimethyl sulfoxide, dioxane or n-hexane one or a combination of several.

The present invention has the following advantages:

The invention uses a dendritic polymer to improve processing fluidity, and the manufactured polyurethane 3D printing material has a low melting temperature, a smooth printing process, no peculiar smell, smooth surface of the product, stable size, and is not easy to shrink.

Detailed ways

The present invention is specifically described below through the examples. It is necessary to point out that the present examples are only used to further illustrate the present invention, and can not be interpreted as limiting the protection scope of the present invention. Those skilled in the art can according to the above invention Some non-essential improvements and adjustments have been made to the content. Unless otherwise specified, the following parts are all molar parts.

Example 1:

(1) Preparation of furan ring polyalcohols:

Add 100 parts of adipic acid, 50 parts of 1,4-butanediol, 50 parts of 2,5-dimethylolfuran, and 0.5 parts of titanate catalyst into the reactor to melt, blow in nitrogen, and set the temperature at 170～230℃ The reaction is carried out for 24-30 hours until the acid value is less than 0.5 mgKOH/g, and a furan ring-containing polyol is obtained.

(2) end group is the preparation of the diisocyanate composition of maleimide:

Under the conditions of N2 protection and mechanical stirring, 100 parts of toluene diisocyanate and 100 parts of dimethylformamide were fully mixed, and 200 parts of N-hydroxyethylmaleimide was added under an ice-water bath, and the addition was completed within 30 minutes. After 2 hours of reaction in an ice-water bath, the reaction was continued at room temperature for 0.5-1 hour, and then the dimethylformamide was evaporated to obtain a diisocyanate composition containing maleimide at both ends.

(3) Preparation of low melting point polyurethane 3D printing materials

Weigh 112 parts of furan ring-containing polyols, 110 parts of toluene diisocyanate, 20 parts of diisocyanate compositions whose terminal groups are maleimides, and 3 parts of dendrimers, and place them at 120°C for melting and dehydration in 2- After 4 hours; at the same time, add it to the twin-screw reaction extruder for reaction, obtain polyurethane particles through underwater pelletizing, dry the obtained polyurethane particles in an oven at 80°C, and mature them for 40 hours to obtain the required polyurethane 3D printing material controlled screw extrusion The temperature of each section of the machine is: 90-120°C, 120-140°C, 140-150°C, 150-160°C, 160-180°C, 90-120°C. After testing, the mechanical properties of the printing wire are: tensile strength 50Mpa, bending strength 95Mpa, bending modulus 3000Mpa, elongation at break 18%.

Example 2:

(1) Preparation of furan ring polyalcohols:

Add 100 parts of adipic acid, 80 parts of 1,4-butanediol, 21 parts of 2,5-dimethylolfuran, and 0.8 parts of titanate catalyst into the reactor to melt, blow in nitrogen, and set the temperature at 220-230°C The reaction is carried out for 35-40 hours until the acid value is less than 0.5mgKOH/g, and a furan ring-containing polyol is obtained.

(2) Preparation of diisocyanate composition containing maleimide at both ends:

Under N2 protection and mechanical stirring conditions, fully mix 50 parts of hexamethylene diisocyanate and 150 parts of dimethylformamide, add 100 parts of N-hydroxyethylmaleimide under ice-water bath, within 30 minutes After the addition is completed, react in an ice-water bath for 2 hours, then continue to react at room temperature for 0.5-1 hour, and then evaporate dimethylformamide to obtain a diisocyanate composition containing maleimide at both ends.

(3) Preparation of low melting point polyurethane 3D printing materials

Weigh 130 parts of polyol containing furan ring, 129 parts of hexamethylene diisocyanate, 10 parts of diisocyanate with maleimide end group, and 3 parts of dendritic polymer, and place them under the condition of 120-150°C respectively After melting and dehydrating for 3 hours; at the same time, add it to a twin-screw reaction extruder for reaction, and obtain polyurethane particles through underwater pelletizing, and place the obtained polyurethane particles in an oven at 60-200°C for drying and aging for 24 hours to obtain the required polyurethane 3D printing Material. . Control the temperature of each section of the screw extruder as follows: 90-120°C, 120-140°C, 140-150°C, 150-160°C, 160-180°C, 90-120°C. After testing, the mechanical properties of the printing wire are: tensile strength 74Mpa, bending strength 82Mpa, bending modulus 2750Mpa, elongation at break 23%.

Claims (5)

1. a kind of polyurethane 3D printing material of low melting temperature, it is characterized in that, adopt following component and raw material ratio, wherein said raw material parts are molar parts: Component raw materials and ratio: 80-150 parts of polyols containing furan ring; 80-120 parts of diisocyanate; 1-20 parts of diisocyanate composition whose end group is maleimide; 0.1-5 parts of dendrimer; Wherein the mole fraction of polyhydric alcohol containing furan ring/the mole fraction of diisocyanate≥1. 2. A method for preparing a polyurethane 3D printing material with a low melting temperature, comprising the following steps, wherein the raw material parts are molar parts: Weigh 80-150 parts of polyols containing furan rings, diisocyanate 80-120 parts, 1-20 parts of diisocyanate composition containing maleimide at both ends, 0.1-5 parts of dendritic polymer, respectively placed at 120-150 ° C for 2-4 hours after melting and dehydration; The reaction is carried out in a twin-screw reaction extruder, and polyurethane particles are obtained by underwater pelletizing. The obtained polyurethane particles are dried and aged in an oven at 60-200°C for 4-72 hours to obtain the required polyurethane 3D printing material; controlled screw extrusion The temperature of each section of the machine is: 90-120°C, 120-140°C, 140-150°C, 150-160°C, 160-180°C, 90-120°C. 3. the preparation method of the polyurethane 3D printing material of a kind of low melting temperature according to claim 2, it is characterized in that described diisocyanate is diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, 1 , A combination of one or more of 5-naphthalene diisocyanatophenol, p-phenylene diisocyanate, dimethyl biphenyl diisocyanate, and hexamethylene diisocyanate. 4. The preparation method of a polyurethane 3D printing material with a low melting temperature according to claim 2, characterized in that the composition and preparation method of the furan ring-containing polyols are as follows: in molar fractions, the organic dicarboxylic acid Add 100 parts of acid, 50-100 parts of diol, 5-50 parts of 2,5-dimethylolfuran, and 0-1 part of titanate catalyst into the reactor for melting, and feed nitrogen gas at 170-230°C React for 5-72h until the acid value is less than 0.5mgKOH/g to obtain a furan ring-containing polyol. 5. the preparation method of the polyurethane 3D printing material of a kind of low melting temperature according to claim 2, it is characterized in that the composition and the preparation method of the diisocyanate composition containing maleimide at both ends are: ₂ Under the conditions of protection and mechanical stirring, mix 100 parts of diisocyanate and 100-200 parts of organic solvent in molar parts, and add 200-210 parts of N-hydroxyethylmaleimide under ice-water bath for 30 minutes After the internal addition is completed, react in an ice-water bath for 2 hours and continue to react at room temperature for 0.5-1h, and then evaporate the organic solvent to obtain a diisocyanate composition containing maleimide at both ends; the organic solvent is dimethyl formaldehyde One or a combination of amides, ethyl acetate, tetrahydrofuran, anhydrous ether, petroleum ether, toluene, acetone, methylene chloride, chloroform, dimethyl sulfoxide, dioxane or n-hexane.