WO2023011410A1

WO2023011410A1 - Foamed material, and preparation method therefor and use thereof

Info

Publication number: WO2023011410A1
Application number: PCT/CN2022/109434
Authority: WO
Inventors: 李敏; 邹海良
Original assignee: 华为技术有限公司
Priority date: 2021-07-31
Filing date: 2022-08-01
Publication date: 2023-02-09
Also published as: CN115678086A; CN116171306A

Abstract

The present application relates to the field of foamed materials; and provides a foamed material and a preparation method therefor, the use of the foamed material, and a grinding material. The foamed material comprises an un-foamed structure, and foamed structures which are dispersed in the un-foamed structure, wherein the foamed structures are internally provided with a plurality of cells, with the average distance between the foamed structures being greater than that between the cells. In the foamed material provided in the present application, the foamed structures have good particle size uniformity and dispersion uniformity, such that the foamed material can be prevented from forming a skin-core structure, and the temperature difference caused by the different heat dissipation of a surface layer and a core layer of the foam material is reduced, so that the foamed material is given the advantage of uniform performance.

Description

A kind of foam material and its preparation method and application

This application requires a Chinese patent submitted to the China Patent Office on July 31, 2021 with the application number 202110877145.X and the application name "polymer foam material and its preparation method, application of polymer foam material, and polishing material" The priority of the application, and claim the priority of the Chinese patent application submitted to the China Patent Office on July 15, 2022, with the application number 202210837183.7 and the application title "A Foaming Material and Its Preparation Method and Application", all of which The contents are incorporated by reference in this application.

technical field

The application belongs to the technical field of foaming materials, and in particular relates to a foaming material, a preparation method thereof, and an application of the foaming material.

Background technique

Foaming material is a kind of microporous material which is based on polymer (plastic, rubber, elastomer or natural polymer material) and has cells inside it. Foaming materials are widely used in the fields of household daily necessities, vehicles, insulating materials, packaging materials, electrical appliances, sports facilities, electronic products, chemicals, and textiles due to their light weight, heat insulation, and sound insulation. For example, the foaming material is used in the electronic industry technology to grind the parts of electronic industrial products or industrial materials that need to be planarized, that is, the polymer foams to form the abrasive material.

Foaming materials can be prepared by foaming polymer microspheres, but during the preparation process, polymeric microspheres are difficult to disperse evenly and have a wide particle size distribution, which affects the application of foaming materials. Taking abrasive materials as an example, as shown in Figure 1, technicians use foamed microspheres to prepare polyurethane abrasive pads. The process of preparing polyurethane abrasive pads by this method includes: firstly, polyacrylonitrile microspheres are prepared by high-pressure suspension polymerization, and the microspheres The interior usually contains low-boiling hydrocarbon substances; then by heating, the shell polymer reaches above Tg, and the low-boiling substance in the inner layer is vaporized and expanded to form hollow foamed microspheres; finally, the hollow microspheres are mixed with isocyanate and cross-linked In the mixture of additives, it can be quickly solidified by pouring to form a microporous material. However, the microsphere preparation process of the abrasive pad obtained by this method is complicated, and the cell size and distribution of the obtained material are not uniform; due to the density difference between polyurethane and microspheres, it is difficult to uniformly disperse the microspheres during the pouring process. The product uniformity is poor; limited by the mixing process, the amount of microspheres added is limited, so the porosity adjustment range of the product is small. Another method for preparing a polyurethane grinding pad is as shown in Figure 2, comprising: first synthesizing a thermoplastic polyurethane material base material, forming a polyurethane sheet through the base material, and the size of the sheet is greater than the size of the grinding pad (800mm × 800mm × 2mm); Then the sheet is heated to above Tg, and supercritical gas is introduced at the same time to impregnate the sheet; finally, the supercritical gas impregnated in the sheet is gasified and expanded by rapid pressure release to form a cell structure. The polyurethane polishing pad obtained by this method has uniform size and distribution of foamed microspheres. See the right side of Figure 2. The material is easy to form a skin-core structure with uneven heat dissipation, and the uniformity of cells is difficult to control, and there are many open-pore structures. .

Therefore, it is particularly important to develop a polymer material with uniform size and distribution of foamed microspheres.

Contents of the invention

The purpose of this application is to provide a foaming material and its preparation method, the application of the foaming material, and a grinding material, aiming to solve the problem of uneven size and distribution of foaming microspheres in the existing foaming materials. When the material is foamed, the size of the material is small, the heat dissipation can be effectively controlled, and the nucleation and diffusion speed of the pores can be effectively controlled. Thus, a porous particle material with uniform pore size is obtained. The abrasive material obtained by particle splicing has the same material performance in the middle edge area, and the material performance between the upper and lower layers and between the sheets is the same.

In order to realize the above-mentioned application purpose, the technical scheme adopted in this application is as follows:

The first aspect of the present application provides a foam material, including a plurality of foam structures, the foam structure has many cells inside, wherein the average distance between the foam structures is greater than the average distance between the cells distance. The size of each foam structure in the foam material is small, the heat transfer and mass transfer in the foaming process are effectively controlled, the cell size of the foam structure is better controlled in a relatively uniform range, and the large cells are reduced existence, reducing defects. Due to the same foaming conditions among different foaming structures, the performance difference of each foaming structure is small, so that the performance difference of the whole foaming material is small, and the material performance is uniform.

For the foam material provided by the application, the particle size of the foam structure is 50 to 30000 microns, and the particle size of the foam structure has better uniformity relative to the foam material; meanwhile, the distance between adjacent foam structures is 2-10000 microns, realize the uniform dispersion of the foam structure in the foam material. In addition, since the foamed structure is dispersed in the continuous phase of the unfoamed material, not only the overall foaming material has better fusion, but also the particle size and dispersion uniformity of the foamed structure can be stabilized. To sum up, the foamed material provided by this application has better particle size uniformity and dispersion uniformity, which can prevent the foamed material from forming a skin-core structure, and reduce the heat loss caused by the difference in heat dissipation between the surface layer and the core layer of the foamed material. The temperature difference gives the foam material the advantage of uniform heat dissipation.

As a possible implementation of the foamed material of the present application, the particle size of the foamed structure is 100-5000 microns, and the average distance between adjacent foamed structures is 50-1000 microns.

As a possible implementation of the foam material of the present application, it is characterized in that the particle size of the foam structure is 200-3500 microns, and the average distance between adjacent foam structures is 50-500 microns .

As a possible implementation of the foam material of the present application, it is characterized in that the particle size of the foam structure is 1500-3500 microns, and the average distance between adjacent foam structures is 50-500 microns .

As a possible implementation of the foamed material of the present application, the average pore diameter of the cells is 1-200 microns, and the distance between adjacent cells is 1-500 microns. In this case, the foam structure in the foam material has cells with uniform particle size and uniform distribution, which is conducive to maintaining the performance stability of each area of the foam material and improving the overall stability of the foam material. Exemplary, when the foaming material is used as the grinding material, since the cells in the foaming structure have better particle size uniformity and dispersion uniformity, the aggregation of the abrasive particles by the large cell structure can be avoided, thereby avoiding aggregation The abrasive particles scratch the workpiece to be ground, such as a wafer, which affects the yield of the workpiece to be ground.

As a possible implementation of the foam material of the present application, the average pore diameter of the cells is 1-60 microns, and the average distance between adjacent cells is 1-60 microns. In this case, the presence of large pores in the foam material is avoided, reducing internal abrasive accumulation and reducing polishing defects.

As a possible implementation of the foam material of the present application, the average pore diameter of the cells is 10-40 microns, and the distance between adjacent cells is 2-40 microns. In this case, the particle size distribution of the foamed structure in the foamed material is more concentrated, and the dispersion of the cells in the foamed structure is more uniform, so that the overall performance of the foamed material is uniform and stable, thus endowing the foamed material with excellent performance. performance. In this case, the cell structure of the material can be more uniform, and the stability of different parts, different layers and different batches of the material can be realized.

As a possible implementation of the foamed material of the present application, the polymer constituting the unfoamed structure and the polymer of the foamed structure may be the same or different.

As a possible implementation of the foamed material of the present application, the particle size of the foamed structure is 200-3500 microns, and the distance between adjacent foamed structures is 50-500 microns. In this case, the particle size distribution of the foamed structure in the foamed material is more concentrated, and the dispersion of the foamed structure in the foamed material is more uniform, and the foamed material can exert more uniform and stable performance, such as heat dissipation uniformity , Scratch resistance, etc.

As a possible implementation of the foamed material of the present application, the polymer constituting the unfoamed continuous phase is the same as the polymer constituting the foamed structure. In this case, the overall fusion of the foamed material is further enhanced, the particle size of the foamed structure and the stability of uniform dispersion are improved, and the scratch resistance of the foamed material is enhanced.

As a possible implementation of the foam material of the present application, the polymer is a thermoplastic polymer, a thermosetting polymer, or a mixture of a thermoplastic polymer and a thermosetting polymer. In this case, since the types of foam materials are not limited, the types of foam materials can be enriched, thereby expanding the application scenarios of foam materials. For example, the foam materials provided by this application can be used as grinding materials, insulation Thermal materials, thermal insulation materials, packaging materials, vibration-absorbing materials, noise-reducing materials, model materials, etc. Not only that, the above materials can be formed into polymer microspheres first, and then foamed by supercritical carbon dioxide foaming technology to form an internally foamed core-shell structure, and then heat-pressed or bonded to form a continuous phase outside the foamed structure. It is beneficial to improve the overall fusion of the foamed material and enhance the scratch resistance of the foamed material.

As a possible implementation of the foam material of the present application, the polymer is selected from thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohol, polyamides, rubber, polyaromatic compounds, fluoropolymers, poly One of imide, polyacrylate, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea.

As a possible implementation of the foam material of the present application, the polymer is selected from thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohol, polyamides, rubber, polyaromatic compounds, fluoropolymers, poly A copolymer or a mixture of at least two of imide, polyacrylate, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea.

As a possible implementation of the foam material of the present application, the polymer includes thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohol, polyamides, rubber, polyaromatic compounds, fluoropolymers, At least one of polyimide, polyacrylate, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea, and selected from thermoplastic elastomers, polyolefins, polycarbonate, polyethylene Formation of at least two of alcohols, polyamides, rubbers, polyaromatics, fluoropolymers, polyimides, polyacrylates, polyether ureas, polyisocyanurates, thermoset polyurethanes, polyureas, polyurethane ureas of copolymers.

The foam materials provided by the above three implementation methods can adjust the type of polymer according to the application requirements of the foam materials, so as to obtain foam materials with different properties, and further expand the application fields of the foam materials.

As a possible implementation of the foam material of the present application, in the foam structure, more than 95% of the cells are closed cells. The high closed cell ratio makes the foamed material rich in a large number of cells with uniform particle size and uniform dispersion, thus endowing the foamed material with excellent foaming microcellular characteristics, which is conducive to improving the performance of the foamed material when used in specific application scenarios . For example, when the foam material is used as an abrasive material, the high closed cell rate improves the flattening effect; when the foam material is used as a heat insulation material or heat preservation material, the high closed cell rate makes a large number of cells in the foam structure effectively hinder the flow of heat, So as to improve the effect of heat insulation and heat preservation; when the foam material is used as a noise reduction material, the high closed cell rate can reduce the circulation of noise, and so on.

The second aspect of the present application provides a method for preparing a foam material, comprising the steps of:

Adding polymer microspheres with a particle size of 20 microns to 3000 microns into water and mixing treatment to obtain a mixture; placing the mixture in a high-pressure reactor, injecting supercritical carbon dioxide into the high-pressure reactor, heating and stirring, and waiting for pressure After the temperature is stabilized, heat preservation treatment is performed, and the pressure is released after the heat preservation is completed, so that the polymer microspheres are foamed to obtain polymer foamed microspheres, and the polymer foamed microspheres have a core-shell structure, including unfoamed shell, and foamed core;

Inject the polymer foamed microspheres into a mold, heat and press, and demould to obtain a foamed material; or mix the binder raw material with the polymer foamed microspheres, inject them into a mold, and heat to react. A foamed material is obtained after demolding, wherein the foamed material includes an unfoamed continuous phase, and a foamed structure dispersed in the unfoamed continuous phase, the foamed structure has cells inside, wherein , the particle size of the foamed structure is 50-3500 microns, and the distance between adjacent foamed structures is 20-500 microns.

The preparation method of the foam material provided by the application has the following advantages:

First, this application selects polymer microspheres with a particle size of 20 microns to 3000 microns to be foamed to form polymer foamed microspheres, avoiding the introduction of microspheres with excessive particle size differences at the front end of the process, so that the microspheres are formed after foaming The foam structure with relatively uniform particle size can effectively control the uneven distribution of the foam structure during the molding process of the foam microspheres, and avoid the temperature difference between the surface layer and the core layer of the foam material due to the difference in heat dissipation, thus giving the foam The advantage of uniform heat dissipation of the material. At the same time, due to the increased size and uniformity of dispersion of polymer microspheres, the size and uniformity of dispersion of cells in the foamed structure are also improved. Thus, the foamed material with improved foam structure and cell size uniformity and distribution uniformity avoids structural differences between the surface and the core layer, thereby improving the performance uniformity of the foamed material.

Second, this application divides the foaming process of the polymer microspheres and the molding process of the foamed material into two steps, which can effectively avoid the foaming caused by uneven heating and heat dissipation during the one-step material integral molding process. The problem of uneven size and distribution can further improve the size uniformity and distribution uniformity of the foam structure and cells.

Third, compared to directly using polymer raw materials to prepare foamed microspheres, this application uses supercritical carbon dioxide to foam polymer microspheres to prepare polymer foamed microspheres, which avoids the bubbles caused by the uneven size of the microspheres. The difference in size results in the formation of large-diameter cells.

Fourth, the present application adopts hot pressing or bonding technology to form the foamed material. Among them, the hot pressing method fuses the surface shell of the polymer foamed microspheres by heating to form a continuous phase, thereby improving the overall fusion of the foamed material, and is conducive to improving the foaming structure and maintaining good dispersion uniformity in the foamed material. The bonding method is to bond the surface shell of polymer foamed microspheres by adding binder raw materials to form a continuous unfoamed structure, and to maintain good dispersion uniformity of the foamed structure in the foamed material.

As a possible implementation of the preparation method of the foam material of the present application, the polymer microspheres are thermoplastic elastomer microspheres, polyolefin microspheres, polycarbonate microspheres, polyvinyl alcohol, polyamide microspheres, Rubber microspheres, polyaromatic compound microspheres, fluoropolymer microspheres, polyimide microspheres, polyacrylate microspheres, polyether urea microspheres, polyisocyanurate microspheres, thermosetting polyurethane microspheres, At least one of polyurea microspheres and polyurethaneurea microspheres.

As a possible implementation of the preparation method of the foam material of the present application, the polymer microspheres are selected from thermoplastic elastomers, polyolefins, polycarbonate, polyvinyl alcohol, polyamides, rubber, polyaromatic compounds, Copolymer microspheres formed from at least two of fluoropolymer, polyimide, polyacrylate, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea.

As a possible implementation of the preparation method of the foam material of the present application, the polymer microspheres include thermoplastic elastomer microspheres, polyolefin microspheres, polycarbonate microspheres, polyvinyl alcohol, polyamide microspheres, Rubber microspheres, polyaromatic compound microspheres, fluoropolymer microspheres, polyimide microspheres, polyacrylate microspheres, polyether urea microspheres, polyisocyanurate microspheres, thermosetting polyurethane microspheres, At least one of polyurea microspheres, polyurethaneurea microspheres, and at least one selected from thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohol, polyamides, rubber, polyaromatic compounds, fluoropolymers, polyimides Copolymer microspheres formed by at least two of amine, polyacrylate, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea.

The polymer microspheres provided by the above three implementation methods can be foamed by supercritical carbon dioxide, and the formed cells have better pore size uniformity and dispersion uniformity; not only that, the polymer foam formed by the above materials Microspheres can be bonded and molded by hot pressing or similar polymer binders, which improves the fusion of foamed materials. In the foamed material thus formed, the structural difference and material difference in different regions are reduced, and the consistency of the material surface and the internal performance of the material is improved, thereby improving the stability of its performance. In addition, by adjusting the type of polymer according to the application requirements of the foamed material, foamed materials with different properties can be obtained, thereby expanding the application field of the foamed material.

As a possible implementation of the preparation method of the foam material of the present application, the polymer microspheres are polyurethane microspheres, and the preparation method of the polyurethane microspheres is: configure an organic solution of polymer polyols, Adding isocyanate to the organic solution of the polymer polyol, mixing and treating, standing for reaction to prepare the polyurethane microspheres. The foaming material formed by using polyurethane microspheres as polymer microspheres has excellent planarization effect as an abrasive material; not only that, after polyurethane microspheres are foamed with supercritical carbon dioxide, they are hot-pressed or bonded to form The high-quality polyurethane abrasive material has good uniformity in cell size, which can prevent the abrasive material from agglomerating locally on the abrasive material and damaging the workpiece to be ground.

As a possible implementation of the preparation method of the foaming material of the present application, in the step of adding isocyanates to the organic solution of the polymer polyol, the molar ratio of isocyanate groups to hydroxyl groups is 1:(1 ˜1.05), adding isocyanate to the organic solution of the polymer polyol. In this application, in the polymerization reaction of polymer polyol and isocyanate polyol, a polymer polyol with a molar content slightly more than that of isocyanate is introduced, so that the more stable isocyanate polyol is used as an end group, thereby obtaining stable polymer microspheres, Prevent the polymer terminated with isocyanic acid from being unstable under conditions such as water, and affect the formation of foaming materials during supercritical carbon dioxide foaming.

As a possible implementation of the preparation method of the foaming material of the present application, in the step of adding isocyanate to the organic solution of the polymer polyol, it also includes: adding a catalyst to the organic solution of the polymer polyol , the catalyst is used to catalyze the polymerization reaction between the polymer polyol and the isocyanate. The rate at which polymer polyols and isocyanates form polymer microspheres can be accelerated by adding a catalyst.

As a possible implementation of the method for preparing the foam material of the present application, the average thickness of the shell layer is 10-30 microns, and the particle size of the core is 20-500 microns. In this case, the size of the foam structure is uniform, and since the average thickness of the shell layer is also relatively uniform, after hot pressing or bonding molding, the shell layer forms a continuous phase and makes the adjacent foam structures relatively uniform. distance, so that the foam structure can be evenly dispersed in the foam material, and the foam material can exert more uniform and stable performance, such as heat dissipation uniformity, scratch resistance, etc.

As a possible implementation of the preparation method of the foamed material of the present application, the polymer foamed microspheres are injected into the mold, and the steps of hot-pressing treatment include:

Heating the polymer foamed microspheres until the temperature is above the T _g of the microsphere polymer and below the T _m ;

The heated polymer foamed microspheres are injected into a mold and pressurized to shape.

In this case, after heat treatment, the shell layers of the polymer foamed microspheres are fused to form a continuous phase, and the cores of the foamed microspheres are fixed in it to form the foamed structure of the foamed material. The resulting foamed material has improved size uniformity and distribution uniformity of the foamed structure, which can reduce structural differences in different regions of the foamed material, improve the consistency of the surface and internal properties of the material, and keep the foamed material stable. performance.

As a possible implementation of the preparation method of the foamed material of the present application, the binder raw material is mixed with the polymer foamed microspheres and injected into the mold, and the heating reaction step includes:

mixing the binder raw material with the polymer foamed microspheres to obtain a mixed solution;

The mixed solution is poured into the mold and heated to shape.

In this case, the binder raw material forms a binder under heating conditions, fuses the shell layer of the polymer foamed microspheres to form a continuous phase, fixes the core of the foamed microspheres therein, and forms the foam of the foamed material. bubble structure. The resulting foamed material has improved size uniformity and distribution uniformity of the foamed structure, which can reduce structural differences in different regions of the foamed material, improve the consistency of the surface and internal properties of the material, and keep the foamed material stable. performance. In addition, the added binder can regulate the porosity of the foamed material, so that the foamed material can be adapted to the needs of different scenarios.

As a possible implementation of the preparation method of the foam material of the present application, the polymer foamed microspheres are polyurethane foamed microspheres; the binder raw materials are isocyanate prepolymers, polymer polyols and crosslinked agent. In this case, the binder formed by isocyanate prepolymer, polymer polyol and crosslinking agent is also polyurethane, which can fuse with the shell layer of polymer foamed microspheres to form a continuous phase with good fusion property, thereby improving Structural and material uniformity of the foamed material.

The third aspect of the present application provides the foaming material described in the first aspect or the foaming material prepared by the method described in the second aspect, which can be used as grinding materials, heat insulation materials, heat preservation materials, packaging materials, vibration damping materials, and noise reduction materials. Application of materials and model materials.

In the foamed material provided by the first aspect of the present application or the foamed material prepared by the method provided in the second aspect, the foamed structure has better particle size uniformity and uniformity of dispersion, and the non-foamed structure forms a continuous phase, so that it can be Reduce the structural difference of the foamed material, improve the consistency of the surface of the material and the internal performance of the material, which is conducive to the stability of the foamed material, such as giving the foamed material uniform heat dissipation, heat preservation performance, vibration reduction performance, noise reduction performance, scratch resistance It can be used as abrasive materials, heat insulation materials, heat preservation materials, packaging materials, vibration damping materials, noise reduction materials, and model materials.

The fourth aspect of the present application provides an abrasive material, which is the foam material described in the first aspect or the foam material prepared by the method described in the second aspect.

The abrasive material provided by this application has a foamed structure dispersed in the continuous phase non-foamed structure, and has better particle size uniformity and dispersion uniformity in the entire abrasive material, thereby reducing the structure difference between the surface layer and the core layer of the abrasive material , and prevent the abrasive material from forming a skin-core structure, reduce the temperature difference between the surface layer and the core layer of the abrasive material due to the difference in heat dissipation, and endow the foamed material with the advantage of uniform heat dissipation. Not only that, the foam structure with uniform particle size is conducive to improving the uniformity of the cell diameter, thereby avoiding the aggregation of the abrasive particles by the large-diameter cells, reducing the scratches of the abrasive material on the workpiece such as the wafer, and improving the flatness. effect. In addition, because the present application can adjust the porosity of the grinding material by providing the size of the polymer microspheres, the expansion ratio of supercritical carbon dioxide, etc. in the method provided by the second aspect, so that it can better meet the requirements of different workpieces to be ground. Material porosity requirements.

Description of drawings

Fig. 1 is the schematic flow sheet that adopts foamed microspheres to prepare polyurethane abrasive pad that prior art provides;

Fig. 2 is the process flow diagram that prior art provides that polyurethane sheet is carried out supercritical carbon dioxide foam;

Fig. 3 is the schematic diagram of the foam material provided by the embodiment of the present application;

Fig. 4 is the preparation process flowchart of the foam material provided by the embodiment of the present application;

Fig. 5 is a schematic flow chart of preparing a foaming material by hot pressing provided in an embodiment of the present application;

Fig. 6 is a schematic flow chart of bonding and preparing foaming materials provided by the embodiment of the present application;

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application clearer, the present application will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

In this application, the term "and/or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, A and/or B may mean: A exists alone, A and B exist simultaneously, and B exists alone Condition. Among them, A and B can be singular or plural. The character "/" generally indicates that the contextual objects are an "or" relationship.

In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one item (unit) of a, b, or c", or "at least one item (unit) of a, b, and c" can mean: a, b, c, a-b( That is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

It should be understood that in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the order of execution, and some or all steps may be executed in parallel or sequentially, and the execution order of each process shall be based on its functions and The internal logic is determined and should not constitute any limitation to the implementation process of the embodiment of the present application.

Terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of this application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

The term "CMP" is the abbreviation of "Chemical mechanical planarization", which means chemical mechanical polishing, which is a technology in the semiconductor device manufacturing process, which is used to planarize the silicon wafer or other substrate materials being processed. The basic principle is to make the workpiece to be ground rotate relative to the grinding pad under the condition of certain pressure and abrasive liquid (a mixture composed of ultra-fine abrasive particles, chemical oxidant and liquid medium), and with the help of the mechanical force of the abrasive particles Grinding and corrosion of chemical oxidants are used to complete the material removal on the surface of the workpiece and obtain a smooth surface.

The term "Tg" is an abbreviation for "glass transition temperature", which means the glass transition temperature, which refers to the temperature corresponding to the transition of a polymer from a glass state to a high elastic state. Tg is the lowest temperature at which molecular segments can move, and it is a relaxation phenomenon of the amorphous part of a polymer from a frozen state to a thawed state.

The term "Tm" is the abbreviation of "Melting Temperature", which means the melting temperature, and refers to the temperature at which the three-dimensional long-range ordered state of the macromolecular chain structure transforms into a disordered viscous fluid state for crystalline polymers, also known as the melting point. Tm is the lower limit of temperature for molding process of crystalline polymer.

The term "TPU" is the abbreviation of "Thermoplastic polyurethanes", which means thermoplastic polyurethane elastomer, which is composed of diisocyanate molecules such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI), macromolecular polyols, low molecular polyols (Chain extender) A polymer material formed by co-reaction and polymerization, which can be melted when heated.

The term "TSU" is the abbreviation of "thermeset polyurethane elastomer", which means thermosetting polyurethane elastomer, which is a kind of polyurethane elastomer that forms a shape by chemical reaction under the action of heat, catalyst, pressure, ultraviolet light, etc., and will no longer melt when heated , strong heat will decompose.

Foaming materials can be widely used in various industries due to their light weight, heat insulation, sound insulation, etc. , noise reduction materials, model materials, etc., but not limited thereto. Among them, the foam structure plays a pivotal role in the formation of light weight, heat insulation, sound insulation and other characteristics of the foam material. In particular, the size difference and dispersion performance of the foamed structure in the foamed material directly affect the structural uniformity and performance uniformity of the foamed material, and further affect the performance of the foamed material. The following takes the grinding material as an example to briefly describe the impact of the size difference and dispersion uniformity of the foam structure in the foam material on the grinding.

The polishing pad formed by polyurethane foam has excellent planarization effect on patterned semiconductor wafers. However, due to the wide particle size distribution of the polymeric microspheres, it is difficult to disperse evenly, resulting in the formation of a large cell structure in the polishing pad, and the large cell structure is easy to gather the abrasive particles in the grinding liquid, and these aggregated abrasive particles are very easy to cause The workpiece to be ground, such as the wafer, is scratched, resulting in defects or even scrapping of the workpiece to be ground.

In view of this, the embodiments of the present application provide a foam material that improves the size uniformity and dispersion uniformity of the foam structure. It should be understood that the foaming materials provided in the embodiments of the present application can not only be used as grinding materials, but also can be used as heat insulation materials, heat preservation materials, packaging materials, vibration damping materials, noise reduction materials, model materials, and through improving The size of the foam structure and the uniformity of dispersion of the foam material should improve its performance when used as the above-mentioned material.

Specifically, as shown in Figure 3, the foamed material provided by the embodiment of the present application includes an unfoamed continuous phase and a foamed structure dispersed in the unfoamed continuous phase, and the unfoamed continuous phase forms a honeycomb-like structure. Since the foamed structure is dispersed in the continuous phase of the unfoamed material, not only the overall foaming material has better fusion, but also the foamed structure can be stabilized to maintain a good particle size and dispersion uniformity.

In the embodiments of the present application, the materials of the unfoamed continuous phase and the foamed structure are both polymer materials, and the polymer constituting the unfoamed continuous phase is the same as or different from the polymer constituting the foamed structure.

In one embodiment, the polymer that makes up the unfoamed continuous phase is the same polymer that makes up the foamed structure. In this case, the fusion between the unfoamed continuous phase and the foamed structure is higher, the overall fusion of the foamed material is enhanced, the overall stability of the material is improved, and the scratch resistance of the foamed material enhanced. Exemplarily, when the foaming material is an abrasive material, when the polymer that forms the unfoamed continuous phase is the same as the polymer that forms the foam structure, it can improve the consistency of the abrasive material, improve the planarization effect of the abrasive material, and reduce Risk of scratching workpieces to be ground by abrasive materials.

In a possible implementation manner, the polymers constituting the unfoamed continuous phase and the foamed structure are thermoplastic polymers, thermosetting polymers, or a mixture of thermoplastic polymers and thermosetting polymers. In this case, since the types of foam materials are not limited, the types of foam materials can be enriched, thereby expanding the application scenarios of foam materials. For example, the foam materials provided in the embodiments of this application can be Different, choose the appropriate polymer material respectively, so that the foaming material can be used as grinding material, heat insulation material, thermal insulation material, packaging material, vibration damping material, noise reduction material, model material, etc. Not only that, the above materials can be formed into polymer microspheres first, and then foamed by supercritical carbon dioxide foaming technology to form an internally foamed core-shell structure, and then heat-pressed or bonded to form a continuous phase outside the foamed structure. It is beneficial to improve the overall fusion of the foamed material and enhance the scratch resistance of the foamed material.

In one possible implementation, the polymer is selected from thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohols, polyamides, rubbers, polyaromatics, fluoropolymers, polyimides, polyacrylates , polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea in one. In this case, the polymer that forms the unfoamed continuous phase and the polymer that forms the foamed structure are selected from one of the above-mentioned polymers, and correspondingly, the foamed material obtained is a thermoplastic elastomer foamed material, a polymer Olefin foam, polycarbonate foam, polyvinyl alcohol foam, polyamide foam, rubber foam, polyaromatic foam, fluorine foam, polyimide foam , Polyacrylate foam material, polyether urea foam material, polyisocyanurate foam material, thermosetting polyurethane foam material, polyurea foam material, polyurethane urea foam material.

In one possible implementation, the polymer is selected from thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohols, polyamides, rubbers, polyaromatics, fluoropolymers, polyimides, polyacrylates , polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea at least two copolymers or mixtures formed. In this case, the polymer that forms the unfoamed continuous phase and the polymer that forms the foamed structure are selected from the same copolymer or the same mixture formed by the above-mentioned polymers. Correspondingly, the foaming material is a thermoplastic elastomer, Polyolefins, polycarbonates, polyvinyl alcohols, polyamides, rubbers, polyaromatics, fluoropolymers, polyimides, polyacrylates, polyether ureas, polyisocyanurates, thermoset polyurethanes, polyureas , a foamed material formed from at least two copolymers formed in polyurethane urea; or the foamed material is a thermoplastic elastomer, polyolefin, polycarbonate, polyvinyl alcohol, polyamide, rubber, polyaromatic compound, fluoropolymer A mixed foam material formed of at least two of polyimide, polyacrylate, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea.

In one possible implementation, the polymer comprises thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohols, polyamides, rubbers, polyaromatics, fluoropolymers, polyimides, polyacrylic acid At least one of ester, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea, and selected from thermoplastic elastomer, polyolefin, polycarbonate, polyvinyl alcohol, polyamide, rubber, A copolymer formed of at least two of polyaromatic compounds, fluoropolymers, polyimides, polyacrylates, polyether ureas, polyisocyanurates, thermoset polyurethanes, polyureas, polyurethane ureas.

In a possible implementation manner, the foam material is used as the grinding material, and the polymer forming the foam structure is a thermoplastic material. The thermoplastic material increases the cold flow of the material, which can effectively reduce the scratch of the workpiece to be ground, such as a wafer. In addition, thermoplastic materials can be melted after heating, which can realize good recycling and reuse, and reduce environmental pollution.

In a possible implementation mode, the foaming material is used as the grinding material, and the polymer forming the unfoamed continuous phase and the polymer forming the foaming structure are polyurethane, the grinding material thus formed has better abrasive properties of the workpiece to be ground. on this basis, by adjusting the particle size and dispersion uniformity of the foam structure, the dispersion uniformity and pore size uniformity of the cells in the foam structure can be further improved, and the formation of large particles in the foam structure can be avoided. The pores of the pore size are small, so as to avoid the damage caused by the aggregation of abrasive particles to the workpiece to be ground, and improve the yield of the workpiece to be ground. Especially for patterned semiconductor wafers, polyurethane abrasives have excellent planarization effects.

Of course, it should be understood that the polymers constituting the unfoamed continuous phase may not be exactly the same as the polymers constituting the foamed structure. Exemplary, the polymer that forms foam structure is polyurethane, the polymer that forms unfoamed continuous phase is the mixture that polyurethane and other polymers form, as the polymer that forms foam structure is TPU, forms unfoamed continuous phase The polymer is a mixture of TPU and TSU.

In the embodiment of the present application, the particle size of the foamed structure is 50-3500 microns, and at the same time, the distance between adjacent foamed structures is 20-500 microns. In this case, the particle size of the foamed structure has better uniformity relative to the foamed material; at the same time, the uniform dispersion of the foamed structure in the foamed material can be achieved, thereby avoiding the foaming material on the surface and core. The structure difference of the layer can improve the consistency of the surface of the foam material and the internal performance of the material. For example, the foamed material provided by the embodiment of the present application can avoid uneven heat dissipation caused by the structural difference between the surface layer and the core layer, thereby giving the foamed material the advantage of uniform heat dissipation; the foamed material provided by the embodiment of the present application can also avoid the surface layer and the core layer. The impact of the difference in core layer structure on the planarization effect of the ground workpiece. Since the thickness of the polymer abrasive material in the application process can be on the order of millimeters (such as a grinding pad), the size of the foam structure of the foam material is too large, or the distance between adjacent foam structures is too large, which will reduce the foaming effect. The microporous properties of the material even make it lose its microporous effect.

Exemplarily, the particle size range of the foam structure in the foam material can be 50-300 microns, 50-400 microns, 50-500 microns, 50-600 microns, 50-800 microns, 50-1000 microns, 50-1500 microns Micron, 50-2000 micron, 50-2500 micron, 50-3000 micron, 50-3500 micron, 100-500 micron, 100-600 micron, 100-800 micron, 100-1000 micron, 100-1500 micron, 100-2000 micron Micron, 100～2500 micron, 100～3000 micron, 100～3500 micron, 150～500 micron, 150～600 micron, 150～800 micron, 200～1000 micron, 200～1500 micron, 200～2000 micron, 200～2500 micron Micron, 200～3000 micron, 200～3500 micron, 300～800 micron, 300～1000 micron, 300～1500 micron, 300～2000 micron, 300～2500 micron, 300～3000 micron, 300～3500 micron, 400～1000 micron Micron, 400～1500 micron, 400～2000 micron, 400～2500 micron, 400～3000 micron, 400～3500 micron, 500～1000 micron, 500～1500 micron, 500～2000 micron, 500～2500 micron, 500～3000 micron Micron, 500～3500 micron, 600～1000 micron, 600～1500 micron, 600～2000 micron, 600～2500 micron, 600～3000 micron, 600～3500 micron, 800～1200 micron, 800～1500 micron, 800～2000 micron Micron, 800～2500 micron, 800～3000 micron, 800～3500 micron, 1000～1500 micron, 1000～2000 micron, 1000～2500 micron, 1000～3000 micron, 1000～3500 micron, 1500～2000 micron, 1500～2500 micron Micron, 1500-3000 micron, 1500-3500 micron, 2000-2500 micron, 2000-3000 micron, 2000-3500 micron, 50-30000 micron, etc. It should be understood that the smaller the particle size range of the foamed structure in the foamed material, the better the particle size uniformity of the foamed structure, which is more conducive to reducing the cell difference in the foamed structure and obtaining a foamed material with uniform properties. .

Exemplarily, the distance between adjacent foam structures can range from 20 to 100 microns, 20 to 150 microns, 20 to 200 microns, 20 to 250 microns, 20 to 300 microns, 20 to 350 microns, 20 to 400 microns Micron, 20-450 micron, 20-500 micron, 50-100 micron, 50-150 micron, 50-200 micron, 50-250 micron, 50-300 micron, 50-350 micron, 50-400 micron, 50-450 micron Micron, 50-500 micron, 80-150 micron, 80-200 micron, 80-250 micron, 80-300 micron, 80-350 micron, 80-400 micron, 80-450 micron, 80-500 micron, 100-150 micron Micron, 100-200 micron, 100-250 micron, 100-300 micron, 100-350 micron, 100-400 micron, 100-450 micron, 100-500 micron, 150-200 micron, 150-250 micron, 150-300 micron Micron, 150-350 micron, 150-400 micron, 150-450 micron, 150-500 micron, 200-250 micron, 200-300 micron, 200-350 micron, 200-400 micron, 200-450 micron, 200-500 micron Micron, 250-300 micron, 250-350 micron, 250-400 micron, 250-450 micron, 250-500 micron, 300-350 micron, 300-400 micron, 300-450 micron, 300-500 micron, 350-400 micron Micron, 350-450 micron, 350-500 micron, 400-450 micron, 400-500 micron, 450-500 micron, 50-1000 micron, etc. It should be understood that the smaller the distance between adjacent foam structures in the foam material, the smaller the structural difference between the surface layer and the core layer of the foam material, and the better the uniformity of material properties. In addition, the smaller the distance between adjacent foam structures, the higher the porosity of the foam structure; on the contrary, the larger the distance between adjacent foam structures, the lower the porosity of the foam structure. In some embodiments, the foaming material is obtained by hot pressing or bonding molding after polymer microspheres are foamed by supercritical carbon dioxide. The process parameters in the foaming process are used to control the foaming degree of the foamed microspheres, that is, to control the ratio of the foamed core to the unfoamed shell, and to obtain foamed materials with different porosities.

In some embodiments, the larger the particle size range of the foam structure in the foam material, the larger the distance between adjacent foam structures; correspondingly, the smaller the particle size range of the foam structure in the foam material, the larger the distance between adjacent foam structures. The smaller the spacing range of the foamed structure. Exemplarily, when the particle size of the foam structure in the foam material is less than 500 microns, the distance between adjacent foam structures is preferably less than 100 microns.

In a possible implementation manner, the particle size of the foamed structure is 100-500 microns, and the distance between adjacent foamed structures is 50-100 microns. In this case, the particle size distribution of the foamed structure in the foamed material is more concentrated, and the dispersion of the foamed structure in the foamed material is more uniform, which is conducive to improving the overall uniformity of the foamed material and making the foamed material It can exert more uniform and stable performance, such as heat dissipation uniformity, scratch resistance and so on.

In the examples of the present application, cells are formed inside the foam structure, which endows the foam material with excellent foaming microcellular properties, such as grinding, heat preservation, noise reduction, vibration reduction and other properties.

In a possible implementation manner, the average pore size of the cells is 1-60 microns, and the distance between adjacent cells is 1-20 microns. In this case, the foam structure in the foam material has cells with uniform particle size and uniform distribution, which is conducive to improving the foaming microcellular characteristics of the foam material; in addition, the foam structure has better size uniformity and Dispersion uniformity, so as to maintain the performance stability of each area of the foam material and improve the overall stability of the foam material. Exemplary, when the foaming material is used as the grinding material, since the cells in the foaming structure have better particle size uniformity and dispersion uniformity, the aggregation of the abrasive particles by the large cell structure can be avoided, thereby avoiding aggregation The abrasive particles scratch the workpiece to be ground, such as a wafer, which affects the yield of the workpiece to be ground.

In a possible implementation manner, the average pore size of the cells is 10-20 microns, and the distance between adjacent cells is 2-8 microns. In this case, the particle size distribution of the foamed structure in the foamed material is more concentrated, and the dispersion of the cells in the foamed structure is more uniform, so that the overall performance of the foamed material is uniform and stable, thus endowing the foamed material with excellent performance. performance.

In a possible implementation, in the foam structure, the average pore diameter of the cells is 1-60 microns, the distance between adjacent cells is 1-20 microns, and more than 95% of the cells are closed cells . In this case, the higher closed cell ratio makes the foamed material rich in a large number of cells with uniform particle size and uniform dispersion, thus endowing the foamed material with excellent foaming microcellular characteristics, which is conducive to improving the foaming material in specific Performance when used in application scenarios. For example, when the foam material is used as an abrasive material, the high closed cell rate improves the flattening effect; when the foam material is used as a heat insulation material or heat preservation material, the high closed cell rate makes a large number of cells in the foam structure effectively hinder the flow of heat, So as to improve the effect of heat insulation and heat preservation; when the foam material is used as a noise reduction material, the high closed cell rate can reduce the circulation of noise, and so on.

In a possible implementation, in the foamed structure, the average pore diameter of the cells is 10-20 microns, the distance between adjacent cells is 2-8 microns, and more than 98% of the cells are closed cells . In this case, the foamed material has more excellent foaming microcellular characteristics, thereby better improving the performance of the foamed material.

With the rapid development of the electronics industry, there are more and more electronic industry product components or industrial materials that need to be planarized, including silicon wafers, flat panel displays, and storage disks. Chemical-mechanical polishing is a common method of planarization, and as a key material in the planarization process, polishing pads have received extensive attention. During the grinding process, the grinding pad needs to have a certain mechanical strength to maintain a certain grinding speed; at the same time, it also needs to have stable grinding performance to reduce the grinding difference between wafers. In addition, polishing pads need to have as few grinding defects as possible in order to maintain high-performance planarization qualities. Therefore, it is very important to seek abrasive materials with good planarization effect. On the basis of the above-mentioned embodiments, as a first embodiment, a foam material is used as an abrasive material. In this case, by improving the foam structure size and dispersion uniformity of the foam material, the structure difference between the surface layer and the core layer of the abrasive material is reduced, and the heat dissipation uniformity of the abrasive material is improved. At the same time, since the foamed structure has better size and dispersion uniformity, the pore size uniformity of the cells in the foamed structure is correspondingly improved, thereby avoiding the formation of large cells in the foamed structure. Since the large cells are easy to gather abrasive particles in the abrasive liquid, causing scratches on the surface of workpieces to be abrasive such as wafers, therefore, the abrasive materials provided in the embodiments of the present application have improved anti-scratch performance.

As a second embodiment, a foam material is used as a heat insulating material. In this case, by improving the foam structure size and dispersion uniformity of the foam material, the difference in the heat flow path in the heat insulation material is reduced, and the consistency of the heat insulation performance between the surface of the material and the interior of the material is improved, thereby improving the insulation performance. Insulation properties of thermal materials.

As a third embodiment, the foam material is used as a thermal insulation material. In this case, by improving the foam structure size and dispersion uniformity of the foaming material, the heat-blocking effect of the thermal insulation material is improved, thereby improving the thermal insulation performance of the thermal insulation material.

As a fourth embodiment, the foam material is used as a vibration damping material. In this case, by improving the foam structure size and dispersion uniformity of the foam material, the transmission effect of the vibration damping material on vibration is improved, and the vibration damping difference of materials in different regions is reduced, thereby improving the vibration damping performance of the vibration damping material .

As a fifth embodiment, the foam material is used as a noise reduction material. In this case, by improving the foam structure size and dispersion uniformity of the foaming material, the noise-absorbing effect of the noise-reducing material on noise can be improved, and the noise-reduction difference of materials in different regions can be reduced, thereby improving the noise-reducing performance of the vibration-damping material .

As a sixth embodiment, since the foam structure size and dispersion uniformity of the foam material are improved, when the foam material is used as a packaging material, the difference in material structure can be reduced, thereby improving the overall performance of the material.

As the seventh embodiment, since the foam structure size and dispersion uniformity of the foam material are improved, when the foam material is used as a model material, the difference in material structure can be reduced, thereby improving the overall performance of each material.

The foaming material provided in the examples of the present application can be prepared by the following method.

Correspondingly, as shown in Figure 4, the embodiment of the present application provides a method for preparing a foamed material, including the following steps:

S10. Add polymer microspheres with a particle size of 20 microns to 3000 microns into water and mix them to obtain a mixture; place the mixture in an autoclave, inject supercritical carbon dioxide into the autoclave, heat and stir, and wait until the pressure and temperature Insulation treatment after stabilization, pressure relief after the end of the insulation, to foam the polymer microspheres to obtain polymer foamed microspheres, and the polymer foamed microspheres have a core-shell structure, including unfoamed shells, and foamed the nucleus.

In this step, the polymer microspheres are solid microspheres obtained by polymerizing monomers. In a possible implementation, the polymer microspheres are thermoplastic elastomer microspheres, polyolefin microspheres, polycarbonate microspheres, polyvinyl alcohol, polyamide microspheres, rubber microspheres, polyaromatic compound microspheres , fluoropolymer microspheres, polyimide microspheres, polyacrylate microspheres, polyether urea microspheres, polyisocyanurate microspheres, thermosetting polyurethane microspheres, polyurea microspheres, polyurethane urea microspheres at least one of .

In one possible implementation, the polymer microspheres are selected from thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohols, polyamides, rubbers, polyaromatic compounds, fluoropolymers, polyimides, poly Copolymer microspheres formed by at least two of acrylate, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea.

In a possible implementation, the polymer microspheres include thermoplastic elastomer microspheres, polyolefin microspheres, polycarbonate microspheres, polyvinyl alcohol, polyamide microspheres, rubber microspheres, polyaromatic compound microspheres , fluoropolymer microspheres, polyimide microspheres, polyacrylate microspheres, polyether urea microspheres, polyisocyanurate microspheres, thermosetting polyurethane microspheres, polyurea microspheres, polyurethane urea microspheres and selected from thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohols, polyamides, rubbers, polyaromatic compounds, fluoropolymers, polyimides, polyacrylates, polyether ureas, Copolymer microspheres formed by at least two of polyisocyanurate, thermosetting polyurethane, polyurea, and polyurethane urea.

The polymer microspheres provided by the above three implementation methods can be foamed by supercritical carbon dioxide, and the formed cells have better pore size uniformity and dispersion uniformity; not only that, the polymer foam formed by the above materials Microspheres can be bonded and molded by hot pressing or similar polymer binders, which improves the fusion of foamed materials. In the resulting foamed material, the structural difference and material difference of different regions are reduced, thereby improving the stability of its performance. In addition, by adjusting the type of polymer according to the application requirements of the foamed material, foamed materials with different properties can be obtained, thereby expanding the application field of the foamed material.

In the embodiment of the present application, polymer microspheres with a particle size of 20 microns to 3000 microns are selected and foamed to form polymer foamed microspheres. In this case, the size of the polymer microspheres can be controlled at the front end of the foaming material preparation process, so that the polymer microspheres form a foam structure with a relatively uniform particle size after foaming, thereby effectively controlling the formation of the foamed microspheres. The problem of uneven distribution of the foaming structure in the process can further reduce the difference between the surface layer and the core layer of the foaming material, improve the consistency of the surface and internal properties of the material, and make the prepared foaming material have uniform and stable performance. Exemplarily, by foaming polymer microspheres with a particle size less than or equal to 3000 microns, the structure difference between the surface layer and the core layer during the molding process is effectively reduced, and the temperature difference caused by the heat dissipation of the surface layer and the internal material is avoided.

Exemplarily, the particle size range of the polymer microspheres can be 20-200 microns, 20-300 microns, 20-400 microns, 20-500 microns, 20-600 microns, 20-800 microns, 20-1000 microns, 20 ～1500 microns, 20～2000 microns, 20～2500 microns, 20～3000 microns, 40～200 microns, 40～300 microns, 40～400 microns, 40～500 microns, 40～600 microns, 40～800 microns, 40 ～1000 microns, 40～1500 microns, 40～2000 microns, 40～2500 microns, 40～3000 microns, 60～200 microns, 60～300 microns, 60～400 microns, 60～500 microns, 60～600 microns, 60 ～800 microns, 60～1000 microns, 60～1500 microns, 60～2000 microns, 60～2500 microns, 60～3000 microns, 100～200 microns, 100～300 microns, 100～400 microns, 100～500 microns, 100 ～600 microns, 100～800 microns, 100～1000 microns, 100～1500 microns, 100～2000 microns, 100～2500 microns, 100～3000 microns, 200～300 microns, 200～400 microns, 200～500 microns, 200 ～600 microns, 200～800 microns, 200～1000 microns, 200～1500 microns, 200～2000 microns, 200～2500 microns, 200～3000 microns, 300～400 microns, 300～500 microns, 300～600 microns, 300 ～800 microns, 300～1000 microns, 300～1500 microns, 300～2000 microns, 300～2500 microns, 300～3000 microns, 400～500 microns, 400～600 microns, 400～800 microns, 400～1000 microns, 400 ～1500 microns, 400～2000 microns, 400～2500 microns, 400～3000 microns, 500～600 microns, 500～800 microns, 500～1000 microns, 500～1500 microns, 500～2000 microns, 500～2500 microns, 500 ～3000 microns, 600～800 microns, 600～1000 microns, 600～1500 microns, 600～2000 microns, 600～2500 microns, 600～3000 microns, 800～1000 microns, 800～1500 microns, 800～2000 microns, 800 ～2500 microns, 800～3000 microns, 1000～1500 microns, 1000～2000 microns, 1000～2500 microns, 1000～3000 microns, 1200～1500 microns, 1200～2000 microns, 120 0-2500 microns, 1200-3000 microns, 1500-2000 microns, 1500-2500 microns, 1500-3000 microns, 2000-2500 microns, 2000-3000 microns, 2500-3000 microns, 50-30000 microns, etc. It should be understood that the smaller the particle size range of the foamed structure in the foamed material, the better the particle size uniformity of the foamed structure, which is more conducive to reducing the cell difference in the foamed structure and obtaining a foamed material with uniform properties. .

In a possible implementation, the polymer microspheres have a particle size of 100-5000 microns. In this case, the foamed structure formed by foaming the polymer microspheres has better particle size uniformity and dispersion uniformity.

In the examples of the present application, polymer microspheres with a suitable size can be obtained by screening. Wherein, polymer microspheres can be prepared by suspension polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization, glass membrane emulsification method, interfacial polymerization, precipitation polymerization, extrusion granulation, cutting and grinding. In a possible implementation manner, polymer microspheres with a particle size of 20 microns to 3000 microns can be directly prepared by suspension polymerization or precipitation polymerization. Not only that, the polymer microspheres prepared by suspension polymerization have good dispersion and are not easy to stick; the polymer microspheres prepared by precipitation polymerization have the advantage of low cost.

In a possible implementation mode, the polymer microspheres are polyurethane microspheres, and the preparation method of the polyurethane microspheres is: configuring an organic solution of polymer polyol, adding isocyanate to the organic solution of polymer polyol, mixing and processing After static reaction, polyurethane microspheres were obtained. The foaming material formed by using polyurethane microspheres as polymer microspheres has excellent planarization effect as an abrasive material; not only that, after polyurethane microspheres are foamed with supercritical carbon dioxide, they are hot-pressed or bonded to form The high-quality polyurethane abrasive material has good uniformity in cell size, which can prevent the abrasive material from agglomerating locally on the abrasive material and damaging the workpiece to be ground.

In this implementation mode, the polymer polyol solution is first configured in the organic solution of the polymer polyol, the concentration of the polymer polyol is reduced, and then the isocyanate is added, so as to avoid the occurrence of excessive local concentration when the polymer polyol and isocyanate are added at the same time. Problems with violent reactions.

In some embodiments, before the organic solution of the polymer polyol is prepared, the polymer polyol is dried; before the isocyanate is added, the isocyanate is dried, so as to avoid introducing water into the reaction system and interfering with the polymerization reaction. The drying method and drying atmosphere are not strictly limited, and a vacuum environment may be used, and an inert atmosphere or air may also be used. Illustratively, the isocyanate and polymer polyol are dried under heat and vacuum. Among them, the heating temperature is lower than the glass transition temperature Tg to prevent the bonding between isocyanates and polymer polyols; the drying efficiency is promoted through vacuum conditions.

In one embodiment, in the step of adding isocyanate to the organic solution of polymer polyol, according to the molar ratio of isocyanate group and hydroxyl group is 1: (1～1.05), in the polymer polyol The isocyanate is added to the organic solution. In this application, in the polymerization reaction of polymer polyol and isocyanate polyol, a polymer polyol with a molar content slightly more than that of isocyanate is introduced, so that the more stable isocyanate polyol is used as an end group, thereby obtaining stable polymer microspheres, Prevent the polymer terminated with isocyanic acid from being unstable under conditions such as water, and affect the formation of foaming materials during supercritical carbon dioxide foaming.

In one embodiment, in the step of adding isocyanate to the organic solution of polymer polyol, it also includes: adding a catalyst to the organic solution of polymer polyol, and the catalyst is used to catalyze the polymerization between polymer polyol and isocyanate reaction. The rate at which polymer polyols and isocyanates form polymer microspheres can be accelerated by adding a catalyst. Exemplarily, the catalyst is an organic amine, such as triethylamine.

After adding isocyanate into the organic solution of polymer polyol, or adding isocyanate and catalyst into the organic solution of polymer polyol, after mixing, let it stand for a period of time to make the conversion rate of reaction monomer reach more than 90%. Wherein, the way of mixing treatment is not strictly limited, and the way of manual shaking can be adopted, but not limited thereto.

Exemplarily, a preparation method of polyurethane microspheres is as follows: drying isocyanate and polymer polyol under heating and vacuum conditions; fully dissolving polyol in acetonitrile and mixing uniformly by ultrasonic waves, then adding isocyanate, and mixing uniformly Standing for reaction; after the reaction is finished, the mixture is centrifuged, and the obtained solid is washed with acetonitrile and dried at elevated temperature to obtain thermoplastic polyurethane microspheres.

In the examples of the present application, supercritical carbon dioxide is used to foam polymer microspheres (solid microspheres) to prepare polymer foamed microspheres. Compared with the method of vaporizing and expanding the low-boiling point hydrocarbons stored in the polymer, the use of supercritical gas foaming can avoid the pore difference caused by the uneven pore size of the microspheres during the gasification, expansion and foaming process, and avoid During the foaming process, large-diameter cells are generated, which improves the size of the cells and the uniformity of dispersion. In particular, when supercritical carbon dioxide is used to prepare abrasive materials, since the foaming process is not easy to form large-diameter cells, it can avoid the aggregation of abrasive particles in large-diameter cells and cause damage to the workpiece to be ground. , the existence of large apertures will lead to the aggregation of abrasive particles and the formation of wafer scratches.

In the embodiment of the present application, before supercritical carbon dioxide foaming, the polymer microspheres were added into water and mixed to obtain a mixture, so as to prevent the polymer microspheres from sticking. Then, the mixture is placed in a high-pressure reactor, and supercritical carbon dioxide is injected into the high-pressure reactor, heated and stirred, and the pressure and temperature are stabilized and then heat-insulated, so that the supercritical carbon dioxide is fully infiltrated into the polymer microspheres. In the examples of the present application, when supercritical carbon dioxide is used for foaming, the foaming temperature is higher than the Tg of the polymer microsphere substrate and the Tm of the low polymer microsphere substrate.

After the heat preservation is over, the pressure relief treatment is carried out, and the supercritical carbon dioxide is changed into gaseous carbon dioxide through rapid pressure relief. The gaseous carbon dioxide formed inside the polymer microsphere has a large diffusion resistance and aggregates to form pores; while the carbon dioxide on the surface of the polymer microsphere escapes, the epidermis forms a structure with fewer pores, that is, the skin structure, also known as the unfoamed shell. Thus, by supercritical carbon dioxide, polymer foamed microspheres are formed. Wherein, the polymer foamed microsphere has a core-shell structure, including a foamed core and a shell layer covering the surface of the core, and the shell layer is an unfoamed shell layer. Polymer foamed microspheres are formed by supercritical carbon dioxide, the pores of the shell are large and small, and the pores formed in the core are small and numerous. After the following steps of hot pressing or bonding molding treatment, the shell material is fused to form a continuous phase, and the cell size and uniformly dispersed core form a foam structure, thereby eliminating the inconsistency of the cell size and distribution on the surface and inside of the foamed microspheres The difference in material structure caused by the foam structure avoids the formation of a core-skin structure with structural differences.

In a possible implementation manner, the average thickness of the shell layer is 10-30 microns, and the particle size of the core is 20-500 microns. In this case, the size of the foam structure is uniform, and since the average thickness of the shell layer is also relatively uniform, after hot pressing or bonding molding, the shell layer forms a continuous phase and makes the adjacent foam structures relatively uniform. distance, so that the foam structure can be evenly dispersed in the foam material, and the foam material can exert more uniform and stable performance, such as heat dissipation uniformity, scratch resistance, etc.

In one embodiment, the polymer microspheres are thermoplastic polyurethane microspheres, and the method of foaming the thermoplastic polyurethane microspheres is: adding the thermoplastic polyurethane microspheres into water and mixing them, and then placing them in a high-pressure reactor; Inject a certain pressure of supercritical carbon dioxide into the reaction kettle, heat and stir, and keep the temperature for a certain period of time after the pressure and temperature are stable; finally, the thermoplastic polyurethane foamed microspheres are obtained through rapid pressure release.

S20. Inject the polymer foamed microspheres into the mold, heat press, and demould to obtain a foamed material; or mix the binder raw material with the polymer foamed microspheres and inject them into the mold, heat the reaction, and demould Afterwards, the foamed material is obtained, wherein the foamed material includes an unfoamed continuous phase, and a foamed structure dispersed in the unfoamed continuous phase, and the foamed structure has cells inside, wherein the particle diameter of the foamed structure is 50-3500 microns, and the distance between adjacent foam structures is 20-500 microns.

This step provides two methods for preparing foamed materials by molding polymer foamed microspheres.

In the first possible implementation mode, the method for preparing foamed polymer microspheres by molding polymer foamed microspheres includes: injecting polymer foamed microspheres into a mold, heat-pressing, and demoulding to obtain a foamed material . Through heat and pressure treatment, the surface shell of polymer foamed microspheres is fused to form a continuous phase to cover the core and form a foamed structure, which can improve the overall fusion of the foamed material, and is conducive to improving the foamed structure in the foamed material. Good dispersion uniformity.

In one embodiment, as shown in Figure 5, the step of preparing foamed material by hot pressing comprises:

The heated polymer foamed microspheres are injected into the mold and pressurized to shape.

In this case, after heat treatment, the shell layers of the polymer foamed microspheres are fused to form a continuous phase, and the cores of the foamed microspheres are fixed in it to form the foamed structure of the foamed material. In the foamed material thus obtained, the size uniformity and distribution uniformity of the foamed structure are improved, which can reduce the structural difference in different regions of the foamed material, so that the foamed material can maintain stable performance.

In this embodiment, the foamed material can be obtained by cooling and demoulding the hot press-molded product.

In the second possible implementation mode, the method for preparing foamed materials by molding polymer foamed microspheres includes: mixing the binder raw material with polymer foamed microspheres, injecting them into a mold, heating for reaction, and demolding Afterwards, a foam material is produced. In the method, by adding binder raw materials, the surface shell layer of the polymer foamed microspheres is bonded to form a continuous non-foamed structure, and the foamed structure is maintained to maintain good dispersion uniformity in the foamed material. In addition, the method can be used to control the content of the adhesive, and then control the porosity of the foamed material.

In a possible implementation manner, the raw material of the binder is mixed with the foamed polymer microspheres and injected into the mold, and the heating reaction step includes:

The mixture is poured into the mold and heated until shaped.

In this case, the binder raw material forms a binder under heating conditions, fuses the shell layer of the polymer foamed microspheres to form a continuous phase, fixes the core of the foamed microspheres therein, and forms the foam of the foamed material. bubble structure. In the foamed material thus obtained, the size uniformity and distribution uniformity of the foamed structure are improved, which can reduce the structural difference in different regions of the foamed material, so that the foamed material can maintain stable performance. In addition, the added binder can regulate the porosity of the foamed material, so that the foamed material can adapt to the needs of different scenarios. In particular, because supercritical carbon dioxide foaming is difficult to prepare foamed materials with low porosity (this is due to the difficulty of the first concentration of supercritical carbon dioxide entering the substrate itself), therefore, the continuous flow rate can be increased by adding a binder. Phase content, thereby reducing material porosity.

In this embodiment, the foamed material can be obtained by cooling and demoulding the bonded and molded product.

In one embodiment, the polymer foamed microspheres are polyurethane foamed microspheres; the binder raw materials are isocyanate prepolymer, polymer polyol and crosslinking agent. At this time, as shown in Figure 6, the binder raw material is mixed with polymer foamed microspheres and then injected into the mold, and the heating reaction step includes: mixing isocyanate prepolymer, polymer polyol, crosslinking agent and polyurethane foam The foam microspheres are evenly mixed, poured into a mold and heated until forming, cooled and demolded to obtain a foamed material. In this case, the binder formed by isocyanate prepolymer, polymer polyol and crosslinking agent is also polyurethane, which can fuse with the shell layer of polymer foamed microspheres to form a continuous phase with good fusion property, thereby improving Structural and material uniformity of the foamed material.

In the embodiment of the present application, the foaming process of the polymer microspheres and the molding process of the foamed material are carried out in two steps, which can effectively avoid the size of the cells formed by foaming due to uneven heating and heat dissipation during the one-step material integral molding process. And the problem of uneven distribution, further improve the size uniformity and distribution uniformity of the foam structure and cells.

In the embodiment of the present application, the porosity can be controlled by adjusting the size of the microspheres, controlling the content of the binder, and adjusting the expansion ratio of supercritical carbon dioxide, so that the preparation of foaming materials with various porosities can be realized, and the pores of the material can be widened Rate adjustable range. The foamed material prepared by the method provided in the embodiment of the present application can also be used as grinding material, heat insulation material, heat preservation material, packaging material, vibration damping material, noise reduction material, and model material.

In the embodiment of the present application, an abrasive material is also provided. The grinding material is the foam material of the first aspect or the foam material prepared by the method of the second aspect. The abrasive material thus obtained has a foamed structure dispersed in the continuous phase non-foamed structure, and has better particle size uniformity and dispersion uniformity in the entire abrasive material, thereby reducing the difference in the structure of the abrasive material surface layer and the core layer , and prevent the abrasive material from forming a skin-core structure, reduce the temperature difference between the surface layer and the core layer of the abrasive material due to the difference in heat dissipation, and endow the foamed material with the advantage of uniform heat dissipation. Not only that, the foam structure with uniform particle size is conducive to improving the uniformity of the cell diameter, thereby avoiding the aggregation of the abrasive particles by the large-diameter cells, reducing the scratches of the abrasive material on the workpiece such as the wafer, and improving the flatness. effect. In addition, because the present application can adjust the porosity of the grinding material by providing the size of the polymer microspheres, the expansion ratio of supercritical carbon dioxide, etc. in the method provided by the second aspect, so that it can better meet the requirements of different workpieces to be ground. Material porosity requirements.

The abrasive materials provided in the embodiments of the present application can be used to grind workpieces such as semiconductor substrates, optical substrates, and magnetic substrates. At this time, the product formed by the abrasive material is called a polishing pad. Exemplarily, workpieces to be ground are semiconductor substrates, wafers, wafers, metallurgy, storage disk surfaces, optical elements, lenses, wafer templates.

Exemplarily, a polishing pad is used to polish a wafer in chip processing as an example. During the grinding process, the grinding pad is installed on the grinding table and rotates with the grinding table. The grinding head fixes the wafer, flips the wafer upside down on the grinding pad to contact it, and applies a certain pressure. Add polishing liquid on the surface of the polishing pad, turn on the grinding head and the grinding table, and make the grinding head rotate with the wafer relative to the grinding table. At this time, the wafer surface and the polishing pad move relatively. Wafer grinding is achieved through the grinding liquid on the surface of the grinding pad. It should be understood that when the workpiece to be ground is other workpieces, for example, when the workpiece to be ground is a semiconductor substrate, wafer, metallurgy, storage disk surface, optical element, lens, wafer template, etc., the wafer is replaced by other workpieces to be ground. Grinding the workpiece, through the same principle, realizes the grinding of the workpiece to be ground.

The following will be described in conjunction with specific embodiments.

Example 1

A preparation method of grinding material, comprising the steps of:

(1) Preparation of TPU microspheres by precipitation method: diphenylmethane diisocyanate (MDI) and polytetrahydrofuran ether-650 (PTMG-650) were vacuum-dried at 95° C. for 3 hours. Add acetonitrile (100g) and PTMG-650 (32.5g, the number of hydroxyl groups is about 100μmol) in a 500mL reaction bottle, and ultrasonically disperse to completely dissolve the PTMG-650; add MDI (13.2g, isocyanate group 100 μmol) and triethylamine (TEA, 1.28 g); after mixing evenly by hand shaking, the reaction bottle was sealed and placed in a constant temperature water bath at 40°C for 5 hours. After the reaction, the mixture was centrifuged, and the obtained solid was washed three times with acetonitrile and then dried at 50° C. for 24 hours to obtain polyurethane microspheres.

The polyurethane microspheres prepared in this step are tested by SEM, and the particle size range of the microspheres is 20-300 microns, and the average particle size is about 100 microns.

(2) Preparation of TPU foamed microspheres: Weigh 50 g of TPU solid microspheres synthesized in step (1), mix with 2500 mL of medium water, and place in an autoclave reaction chamber equipped with a porous plate at the bottom. Inject 12MPa CO ₂ into the reaction chamber through a high-pressure fluid metering pump, and discharge the air inside the reaction kettle; at the same time, turn on the autoclave controller to heat the material system to 108°C, and the stirring rate is 300rpm. After the pressure and temperature are stable, the heat preservation and pressure holding stage is started, and the time is 2 hours. Turn off the high-pressure fluid metering pump, and then quickly open the ball valve connected to the discharge pipe, the suspended medium will enter the collection barrel. Turn off the autoclave controller, stop heating and stirring. Open the lid of the kettle, take out the foamed beads from the reaction chamber, and measure the initial foaming ratio. The obtained foamed beads are washed, and placed under normal temperature and pressure for more than 48 hours to obtain matured beads.

The TPU foamed microspheres prepared in this step are tested by SEM. The particle size of the microspheres ranges from 20 to 500 microns, the average particle size is about 200 microns, and the average thickness of the unfoamed structure (shell layer) ranges from 10 to 30 microns. Microns, the average thickness of the shell is about 20 microns, the distance between adjacent cells is 1-20 microns, the average distance between adjacent cells is about 5 microns, and the size of the cells is about 1-20 microns. 60 microns, with an average pore size of about 10 microns.

(3) TPU compression molding:

Preheat the TPU foamed microspheres prepared in step (2) at a temperature of 90°C, place the preheated TPU foamed microspheres in a preheated mold (110°C), and continue heating the mold, The temperature was maintained at -105-115°C and pressure was applied to the mold for 10 minutes. Slowly cool down the mold to room temperature (30 minutes), take it out from the mold, and obtain the grinding material, namely the base material of the grinding pad.

The grinding material prepared in this step is tested by SEM, and the distance range between adjacent foam structures is 20-60 microns, and the average distance is about 40 microns; ~500 microns, with an average diameter of about 200 microns. The distance between adjacent cells ranges from 1 to 20 microns, the average distance between adjacent cells is about 5 microns, the size range of the cells is about 1 to 60 microns, and the average pore size is about 10 microns.

The abrasive material prepared in Example 1 has an average pore size of about 10 microns, more than 95% of which are closed-cell structures, the cells are evenly distributed, and the hardness of the abrasive material can be adjusted. This is attributable to: the foaming process and the molding process of the grinding material are carried out in two steps in this embodiment, which effectively avoids the problem of cell inhomogeneity caused by uneven heating and heat dissipation during the gas heating and expansion foaming process; at the same time The introduction of microspheres with the second structure is avoided, and the process difficulty is reduced. For the grinding material prepared in Example 1, the upper and lower layers, and the cells between the middle and the edge are evenly distributed. The hardness of the final abrasive material is about 30D, the density of the abrasive material is about 0.76g/cm ³ and the compressibility is about 1.3.

Example 2

A preparation method of grinding material, comprising the steps of:

(3) Compression molding of TPU and TSU:

Weigh the TPU foamed solid microspheres prepared by 480g step (2), add the prepolymer (isocyanate end-capping) of 300g TDI and PTMG (Mn=650), then add polyether polyol 4110 and p-di-o-chloroaniline methane The mixture (the molar ratio of NCO:OH is 2.2:1), mixed evenly and degassed, poured into the mold, the temperature was maintained at about 80°C, and the temperature was maintained for about 24h, cooled to room temperature within 30min, ejected from the mold, and taken out from the mold Abrasive pad substrate.

The grinding material prepared by this step is tested by SEM, and the distance range between adjacent foam structures is 22～80 microns, and the average distance is about 50 microns; the honeycomb (foam structure) diameter range of the honeycomb unfoamed structure is 30 ~500 microns, with an average diameter of about 230 microns. The distance between adjacent cells ranges from 1 to 20 microns, the average distance between adjacent cells is about 5 microns, the size range of the cells is about 1 to 60 microns, and the average pore size is about 10 microns.

The abrasive material prepared in Example 2 has an average pore size of about 100 microns, more than 95% of which is a closed-cell structure, and the distribution of cells is uniform. This is attributable to: the foaming process and the molding process of the grinding material are carried out in two steps in this embodiment, which effectively avoids the problem of cell inhomogeneity caused by uneven heating and heat dissipation during the gas heating and expansion foaming process; at the same time The introduction of microspheres with the second structure is avoided, and the process difficulty is reduced. After the grinding material prepared in Example 2 is cut into a grinding pad, the upper and lower layers of the grinding pad, the cells between the middle and the edge are evenly distributed. The hardness of the final abrasive material is about 35D, the density of the abrasive material is about 0.97g/cm ³ , and the compressibility is about 0.9.

Compared with Example 1, the abrasive material prepared in Example 2 introduces a thermosetting polyurethane material, so that the continuous unfoamed phase is a mixture of thermoplastic and thermosetting polyurethane, but the foam structure is still a thermoplastic polyurethane material . This technology can expand the material selection range of abrasive materials, realize the performance adjustment of wide distribution of abrasive performance, and is more conducive to the realization of abrasive materials with various performance characteristics.

Example 3

A preparation method of grinding material, comprising the steps of:

(1) Preparation of TPU foamed microspheres: Weigh 50 g of extruded and granulated TPU solid microspheres, mix them with 2500 mL of medium water, and place them in an autoclave reaction chamber equipped with a porous plate at the bottom. Inject 12MPa CO ₂ into the reaction chamber through a high-pressure fluid metering pump, and discharge the air inside the reaction kettle; at the same time, turn on the autoclave controller to heat the material system to 108°C, and the stirring rate is 300rpm. After the pressure and temperature are stable, the heat preservation and pressure holding stage is started, and the time is 2 hours. Turn off the high-pressure fluid metering pump, and then quickly open the ball valve connected to the discharge pipe, the suspended medium will enter the collection barrel. Turn off the autoclave controller, stop heating and stirring. Open the lid of the kettle, take out the foamed beads from the reaction chamber, and measure the initial foaming ratio. The obtained foamed beads are washed, and placed under normal temperature and pressure for more than 48 hours to obtain matured beads.

The TPU foamed microspheres prepared in this step are tested by SEM. The particle size range of the microspheres is 2000-3000 microns, the average particle size is about 2800 microns, and the average thickness of the unfoamed structure (shell layer) ranges from 10 to 50 microns. Microns, the average thickness of the shell is about 30 microns, the distance between adjacent cells is 1-20 microns, the average distance between adjacent cells is about 10 microns, and the size of the cells is about 1-20 microns 60 microns, with an average pore size of approximately 30 microns.

(2) Compression molding of TPU and TSU:

Weigh 520g of the TPU foamed solid microspheres prepared in step (1), add 300g of the mixture of adhesive A and adhesive B, mix evenly and degas, and inject it into the mold. The temperature is maintained at about 80°C, and the reaction temperature is maintained at about Cool to room temperature within 24 hours and 30 minutes, take out the mold, and take out the polishing pad base material from the mold.

The abrasive material prepared in this step is tested by SEM. The distance between adjacent foamed structures ranges from 20 to 200 microns, with an average distance of about 50 microns; the diameter of the unfoamed structure ranges from 2800 to 3500 microns, with an average diameter of about 3000 microns. The distance between adjacent cells ranges from 1 to 20 microns, the average distance between adjacent cells is about 10 microns, the size range of the cells is about 1 to 60 microns, and the average pore size is about 30 microns.

The abrasive material prepared in Example 3 has an average pore size of about 30 microns, more than 95% of which is a closed-cell structure, and the cells are evenly distributed. This is attributable to: the foaming process and the molding process of the grinding material are carried out in two steps in this embodiment, which effectively avoids the problem of cell inhomogeneity caused by uneven heating and heat dissipation during the gas heating and expansion foaming process; at the same time The introduction of microspheres with the second structure is avoided, and the process difficulty is reduced. After the grinding material prepared in Example 3 is cut into a grinding pad, the upper and lower layers of the grinding pad, the cells between the middle and the edge are evenly distributed. The hardness of the final abrasive material is about 45D, the density of the abrasive material is about 0.89g/cm ³ , and the compressibility is about 0.8.

Compared with Example 1, the grinding material prepared in Example 3 introduces a thermosetting polyurethane material, so that the continuous unfoamed phase is a mixture of thermoplastic and thermosetting polyurethane, but the foam structure is still a thermoplastic polyurethane material . This technology can expand the material selection range of abrasive materials, realize the performance adjustment of wide distribution of abrasive performance, and is more conducive to the realization of abrasive materials with various performance characteristics.

Compared with Example 2, the abrasive material prepared in Example 3 introduced polyols with lower molecular weight, and the resulting abrasive material had greater hardness.

Example 4

A preparation method of grinding material, comprising the steps of:

(2) Compression molding of TPU and TSU:

Weigh 80g of TPU foamed solid microspheres prepared by step (2), add 400g of TDI and PTMG (Mn=650) prepolymer (isocyanate end-capping), then add polyether polyol 4110 and p-di-o-chloroaniline methane The mixture (the molar ratio of NCO:OH is 2.2:1), mixed evenly and degassed, poured into the mold, the temperature was maintained at about 80°C, and the temperature was maintained for about 24h, cooled to room temperature within 30min, ejected from the mold, and taken out from the mold Abrasive pad substrate.

The abrasive material prepared in this step is tested by SEM. The distance between adjacent foamed structures ranges from 20 to 500 microns, with an average distance of about 100 microns; the diameter of the unfoamed structure ranges from 2800 to 3800 microns, with an average diameter of about 3300 microns. The distance between adjacent cells ranges from 1 to 20 microns, the average distance between adjacent cells is about 10 microns, the size range of the cells is about 1 to 60 microns, and the average pore size is about 30 microns.

The abrasive material prepared in Example 4 has an average pore size of about 3 microns, more than 95% of which is a closed-cell structure, and the cells are evenly distributed. This is attributable to: the foaming process and the molding process of the grinding material are carried out in two steps in this embodiment, which effectively avoids the problem of cell inhomogeneity caused by uneven heating and heat dissipation during the gas heating and expansion foaming process; at the same time The introduction of microspheres with the second structure is avoided, and the process difficulty is reduced. After cutting the grinding material prepared in Example 4 into grinding pads, the upper and lower layers of the grinding pad, the cells between the middle and the edge are evenly distributed. The hardness of the final abrasive material is about 55D, the density of the abrasive material is about 1.18g/cm ³ , and the compressibility is about 0.5.

Compared with Examples 1 to 3, the abrasive material prepared in Example 4 has reduced the content of foamed microspheres (adhesive is added), and the obtained abrasive material has greater hardness, higher density and lower compressibility.

Finally, it should be noted that: the above is only the specific implementation of the application, but the protection scope of the application is not limited thereto, and any changes or replacements within the technical scope disclosed in the application should be covered by the scope of the application. within the scope of protection. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

A foaming material is characterized in that it includes a plurality of foaming structures, and the foaming structures have multiple cells inside, wherein the average distance between the foaming structures is greater than the average distance between the cells.
The foam material according to claim 1, characterized in that, the particle size of the foam structure is 50-30000 microns, and the average distance between adjacent foam structures is 2-10000 microns.
The foam material according to claim 1, characterized in that, the particle size of the foam structure is 100-5000 microns, and the average distance between adjacent foam structures is 50-1000 microns.
The foam material according to claim 1, characterized in that, the particle size of the foam structure is 200-3500 microns, and the average distance between adjacent foam structures is 50-500 microns.
The foam material according to claim 1, characterized in that, the average pore diameter of the cells is 1-200 microns, and the average distance between adjacent cells is 1-500 microns.
The foam material according to claim 1, characterized in that, the average pore diameter of the cells is 1-60 microns, and the average distance between adjacent cells is 1-60 microns.
The foam material according to claim 1, characterized in that, the average pore diameter of the cells is 10-40 microns, and the average distance between adjacent cells is 2-40 microns.
The foamed material of claim 1, wherein said foamed material comprises an unfoamed structure dispersed within said foamed structure.
The foam material according to any one of claims 1 to 7, characterized in that, the polymer constituting the unfoamed structure and the polymer of the foamed structure can be the same or different.
The foam material according to claims 1 to 8, wherein at least one of the polymer of the unfoamed structure and the polymer of the foamed structure is a thermoplastic polymer, a thermosetting polymer, or a thermoplastic A mixture of polymers and thermosetting polymers.
The foamed material according to claim 10, wherein the foamed structure is a thermoplastic polymer, and the unfoamed structure is a thermosetting polymer.
The foam material according to claim 10, wherein at least one of the polymer of the unfoamed structure and the polymer of the foamed structure is selected from the group consisting of thermoplastic elastomers, polyolefins, polycarbonates, One of polyvinyl alcohol, polyamide, rubber, polyaromatic compound, fluoropolymer, polyimide, polyacrylate, polyether urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea , and/or the polymer is selected from the group consisting of thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohols, polyamides, rubbers, polyaromatics, fluoropolymers, polyimides, polyacrylates, polyethers A copolymer or a mixture of at least two of urea, polyisocyanurate, thermosetting polyurethane, polyurea, polyurethane urea.
The foam material according to any one of claims 1 to 7, characterized in that, in the foam structure, more than 95% of the cells are closed cells.
The foam material according to any one of claims 1 to 7, characterized in that the density of the material ranges from 0.3 to 1.1 g/cm3.
The foam material according to any one of claims 1 to 7, characterized in that the density range of the material is 0.6-1 g/cm3.
The cell according to claim 1, characterized in that, in the same foam structure, the cell wall and the polymer between adjacent cells are the same material.
The unfoamed structure according to claim 1, characterized in that the cell ratio is <10%.
Unfoamed structure according to claim 1, characterized in that the number of voids with a size > 200 microns is less than that of the foamed structure.
A kind of preparation method of foam material is characterized in that, comprises the steps:

Adding polymer microspheres with a particle size of 20 microns to 3000 microns into water and mixing treatment to obtain a mixture; placing the mixture in a high-pressure reactor, injecting supercritical gas into the high-pressure reactor, heating and stirring, and waiting for pressure After the temperature is stabilized, heat preservation treatment is performed, and the pressure is released after the heat preservation is completed, so that the polymer microspheres are foamed to obtain polymer foamed microspheres, and the polymer foamed microspheres have a core-shell structure, including unfoamed shell, and foamed core;

Inject the polymer foamed microspheres into a mold, heat and press, and demould to obtain a foamed material; or mix the binder raw material with the polymer foamed microspheres, inject them into a mold, and heat to react. A foamed material is obtained after demolding, wherein the foamed material includes an unfoamed continuous phase, and a foamed structure dispersed in the unfoamed continuous phase, the foamed structure has cells inside, wherein , the particle size of the foamed structure is 50-3500 microns, and the distance between adjacent foamed structures is 20-500 microns.
The preparation method of foaming material as claimed in claim 19, is characterized in that, described polymer microsphere is thermoplastic elastomer microsphere, polyolefin microsphere, polycarbonate microsphere, polyvinyl alcohol, polyamide microsphere , rubber microspheres, polyaromatic compound microspheres, fluoropolymer microspheres, polyimide microspheres, polyacrylate microspheres, polyether urea microspheres, polyisocyanurate microspheres, thermosetting polyurethane microspheres , at least one of polyurea microspheres, polyurethaneurea microspheres, and/or

The polymeric microspheres are selected from thermoplastic elastomers, polyolefins, polycarbonates, polyvinyl alcohols, polyamides, rubbers, polyaromatic compounds, fluoropolymers, polyimides, polyacrylates, polyether ureas, Copolymer microspheres formed by at least two of polyisocyanurate, thermosetting polyurethane, polyurea, and polyurethane urea.
The preparation method of foaming material as claimed in claim 19, is characterized in that, described polymer microsphere is polyurethane microsphere, and the preparation method of described polyurethane microsphere is: configure the organic solution of polymer polyol, in The isocyanate is added to the organic solution of the polymer polyol, mixed and treated, and left to stand for reaction to prepare the polyurethane microspheres.
The preparation method of foaming material as claimed in claim 19, is characterized in that, in the step of adding isocyanate in the organic solution of described polymer polyol, according to the mol ratio of isocyanate group and hydroxyl is 1:( 1 to 1.05), adding isocyanate to the organic solution of the polymer polyol.
The preparation method of foaming material as claimed in claim 21, is characterized in that, in the step of adding isocyanate in the organic solution of described polymer polyol, also comprises:

A catalyst is added to the organic solution of the polymer polyol, and the catalyst is used to catalyze the polymerization reaction between the polymer polyol and the isocyanate.
The method for preparing a foam material according to any one of claims 19 to 23, wherein the average thickness of the shell layer is 10-30 microns, and the particle diameter of the core is 20-500 microns.
The preparation method of foamed material as described in any one of claims 19 to 23, is characterized in that, described polymer foamed microsphere is injected in the mould, and the step of hot-pressing treatment comprises:

heating the polymer foamed microspheres until the temperature is above Tg and below Tm of the microsphere polymer;

The heated polymer foamed microspheres are injected into a mold and pressurized to shape.
The method for preparing a foamed material as claimed in any one of claims 19 to 23, wherein the binder raw material is mixed with the polymer foamed microspheres and injected into a mold, and the heating reaction step comprises:

mixing the binder raw material with the polymer foamed microspheres to obtain a mixed solution;

The mixed solution is poured into the mold and heated to shape.
The preparation method of foaming material as claimed in claim 26, is characterized in that, described polymer foamed microsphere is polyurethane foamed microsphere; Described binder raw material is isocyanate prepolymer, polymer polyol and cross-linking agent. joint agent.
The foaming material as described in any one of claims 1 to 18 or the foaming material that any one of claims 19 to 27 methods make, as grinding material, heat insulation material, thermal insulation material, packaging material, vibration damping Application of materials, noise-reducing materials, and model materials.
An abrasive material, characterized in that the abrasive material is the foam material according to any one of claims 1 to 18 or the foam material prepared by the method according to any one of claims 19 to 27.