Preparation method of high-density and high-hardness foamed polyurethane polishing pad

Abstract

The invention is applied to the technical field of polishing pad preparation, and particularly discloses a preparation method of a high-density and high-hardness foamed polyurethane polishing pad, which comprises the following steps: S1, raw material pretreatment; s2, a prepolymer synthesis step; s3, a foaming and forming step; s4, demolding and post-processing are carried out; and S5, sheet detection and formula optimization: detecting the hardness and density of the treated polishing pad finished product, and correspondingly adjusting the mixing ratio of the raw materials according to the detection result. According to the preparation method of the high-density and high-hardness foamed polyurethane polishing pad, polyether polyol and polyester polyol are mixed and then react with isocyanate, the polyether polyol and the polyester polyol do not react, and the polyether polyol and the polyester polyol jointly participate in the reaction of the isocyanate after being mixed, so that the high-density and high-hardness foamed polyurethane polishing pad is prepared. The generated polymer combines the advantages of polyether polyol and polyester polyol, and has stronger mechanical properties and chemical resistance than a polymer generated from a single component, so that the quality of a finished product of the polishing pad can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of polishing pad preparation, in particular to a method for preparing a high-density and high-hardness foamed polyurethane polishing pad. Background Art

[0002] Polishing pads are a kind of sheet material with certain flexibility, elasticity and wear resistance. They are used in conjunction with polishing liquid during the polishing process. Through friction with the surface of the workpiece being polished, they remove tiny flaws, scratches and unevenness on the surface of the workpiece, so that the surface of the workpiece can meet the required smoothness and precision requirements. Polishing pads are made of a variety of materials, among which polyurethane polishing pads have good elasticity and flexibility, and strong machinability, and are suitable for different polishing equipment and needs. Therefore, polyurethane polishing pads have a wide range of uses.

[0003] At present, the hardness of conventional polyurethane polishing pads is 73-82A and the density is 420g / cm 3 It can also maintain good flexibility. If the hardness exceeds 88A and the density is 600g / cm 3 The above-mentioned phenomenon will cause the material to become brittle, that is, to break in half, making the processing difficult and unable to be processed into the desired size, thus affecting the application occasions of the polyurethane polishing pad. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a high-density and high-hardness foamed polyurethane polishing pad to solve the problem in the above background technology that when the hardness of the polyurethane polishing pad exceeds a certain range, the material becomes brittle and difficult to process.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a high-density and high-hardness foamed polyurethane polishing pad, comprising the following steps:

[0006] S1. Raw material pretreatment step, drying the synthetic raw materials to avoid moisture affecting the polymerization process;

[0007] S2. Prepolymer synthesis step, in which part of the mixed polyol is pre-reacted with isocyanate to form a prepolymer, and the prepolymer is reacted and mixed with the remaining polyol again and an auxiliary reagent is added;

[0008] S3 foaming and molding step, the mixed raw materials are injected into the mold, foaming and curing;

[0009] S4 demolding and post-processing steps, the raw material after molding is removed from the mold to obtain a finished polishing pad, the polishing pad is surface treated to obtain the final product;

[0010] S5. The step of tablet detection and formula optimization is to test the hardness and density of the finished polishing pad after treatment, and adjust the raw material mixing ratio accordingly according to the test results;

[0011] Preferably, in the raw material pretreatment step S1, the polyol is dried at a drying temperature of 120° C. for 2-4 hours to ensure that the water content of the raw material polyol drops below 0.05%.

[0012] By adopting the above technical solution, the water content of the polyol in the raw material is dried to below 0.05%, ensuring that in the subsequent polymerization reaction, there is no water in the polyol to interfere with the reaction process.

[0013] Preferably, the raw materials in the S2 prepolymer synthesis step include two components, respectively marked as component A and component B, the component A includes polyether polyol and polyester polyol, the component B is isocyanate, the polyether polyol and polyester polyol in component A are mixed into a polyol mixture, and the polyol mixture is divided into two parts, one of which is mixed with the isocyanate of component B to form a prepolymer.

[0014] By adopting the above technical solution and utilizing a two-component polymerization reaction, the advantages of polyether polyol and polyester polyol can be combined to increase the mechanical properties of the polishing pad.

[0015] Preferably, in the S3 foaming and molding step, the prepolymer is mixed with another part of the polyol mixture, and triethylamine catalyst, ethylenediamine chain extender, calcium carbonate filler and carbon dioxide foaming agent are added to generate a raw material mixture, which is injected into a mold and heated and cured to generate a polishing pad product.

[0016] By adopting the above technical scheme, the reaction process can be accelerated by using triethylamine catalyst, and the ethylenediamine chain extender can increase the molecular weight of the polymer, thereby improving the mechanical properties.

[0017] Preferably, the triethylamine catalyst promotes the reaction between isocyanate and polyol, the ethylenediamine chain extender reacts with the isocyanate end groups in the prepolymer to increase the molecular weight of the polyurethane, and the calcium carbonate filler can increase the overall density of the foamed polyurethane.

[0018] By adopting the above technical solution and using calcium carbonate filler, the overall density of the foamed polyurethane can be increased, thereby improving the finished product performance of the polishing pad.

[0019] Preferably, in the S4 demolding and post-processing step, the solidified polishing pad is cooled to room temperature for demolding, and the demolded polishing pad is subjected to a trimming operation, wherein the trimming operation includes cutting and grinding to obtain a polishing pad of a desired size, and a layer of silicone coating is coated on the surface of the trimmed polishing pad, wherein the silicone coating improves the hardness and wear resistance of the polishing pad surface.

[0020] By adopting the above technical solution and performing post-treatment on the polishing pad after demoulding, the hardness and wear resistance of the polishing pad surface can be further increased.

[0021] Preferably, in the S5 tablet detection and formula optimization step, the hardness and density of the finished polishing pad are tested, and the raw material mixing ratio is adjusted accordingly according to the test results. The adjustment method is as follows:

[0022] Increasing the amount of isocyanate to improve the density and hardness of the polishing pad, wherein the amount of isocyanate increased is 10%-20%;

[0023] Reducing the amount of polyols used. When the amount of polyols used is reduced, the isocyanate content in the reaction increases accordingly, thereby increasing the density and hardness of the polishing pad;

[0024] The amount of foaming agent used is reduced, which reduces the size and number of cells in the polishing pad, makes the structure of the polyurethane polymer more compact, and increases the density and hardness.

[0025] By adopting the above technical solution and adjusting the formula using the data after the polishing pad finished product inspection, the performance of the polishing pad can be improved.

[0026] Preferably, the reaction temperature in steps S1 to S5 increases in a gradient, the temperature in the raw material mixing stage is 20°C-30°C, the temperature in the prepolymer and foaming stage is 30°C-50°C, the temperature in the curing stage is 50°C-80°C, and the reactions in each stage are preheated to increase the temperature gradually.

[0027] By adopting the above technical solution and heating the reaction process by preheating, the occurrence of side reactions can be suppressed and the quality and performance of the product can be improved.

[0028] Compared with the prior art, the invention has the following beneficial effects: the preparation method of the high-density and high-hardness foamed polyurethane polishing pad:

[0029] 1. In the present invention, polyether polyol and polyester polyol are mixed and reacted with isocyanate. The polyether polyol and polyester polyol do not react with each other, but participate in the reaction of isocyanate together after mixing. The generated polymer combines the advantages of polyether polyol and polyester polyol, and has stronger mechanical properties and chemical resistance than the polymer generated by a single component, thereby improving the quality of the finished polishing pad;

[0030] Furthermore, during the reaction of the mixed polyol and the isocyanate, a part of the mixed polyol is first reacted with the isocyanate to form a prepolymer, and then the prepolymer is reacted with the remaining mixed polyol, so that the polishing pad reacts relatively mildly during the generation process and is easy to control, thereby obtaining a polymer with more stable performance;

[0031] Furthermore, during the reaction of the prepolymer and the remaining mixed polyol, a triethylamine catalyst is added to accelerate the reaction process, and an ethylenediamine chain extender reacts with the isocyanate end groups in the prepolymer to increase the molecular weight of the polyurethane, thereby improving the mechanical properties of the finished polishing pad.

[0032] 2. In the present invention, different reaction temperatures are used in different reaction stages to ensure the best quality of the finished polishing pad, and preheating is used for heating in each reaction stage. Through preheating, the polyurethane synthesis reaction can be carried out quickly at a relatively high temperature, reducing the time that the reaction system is in an unstable state, thereby effectively inhibiting the occurrence of side reactions and improving the quality and performance of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of the steps of the present invention;

[0034] Figure 2 It is a schematic diagram of the process structure of the present invention;

[0035] Figure 3 It is a schematic diagram of the reaction temperature change structure of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] See also Figure 1-Figure 3 The present invention provides a technical solution: a method for preparing a high-density and high-hardness foamed polyurethane polishing pad.

[0038] S1. Raw material pretreatment step, drying the synthetic raw materials to prevent moisture from affecting the polymerization process; S2. Prepolymer synthesis step, pre-reacting part of the mixed polyols with isocyanate to generate prepolymers, and the prepolymers and the remaining polyols react and mix again and add auxiliary reagents; S3. Foaming and molding step, injecting the mixed raw materials into the mold for foaming and curing molding; S4. Demolding and post-processing step, the molded raw materials are removed from the mold to obtain a finished polishing pad, and the polishing pad is surface treated to obtain the final product; S5. Sheet detection and formula optimization step, the hardness and density of the treated polishing pad product are tested, and the raw material mixing ratio is adjusted accordingly according to the test results;

[0039] like Figure 1As shown, in the process of preparing the foamed polyurethane polishing pad, the synthetic raw materials are first dried to prevent moisture from affecting the subsequent polymerization reaction process, and a part of the mixed polyol is pre-reacted with isocyanate to generate a prepolymer. The generated prepolymer is reacted with the remaining mixed polyol, and the corresponding auxiliary reagents are added for mixing. After mixing, it is injected into a mold to perform foaming and curing molding steps. The molded polishing pad is demolded and post-processed to obtain a finished polishing pad. The hardness and density of the finished polishing pad are tested, and the mixing ratio in the raw materials is adjusted accordingly according to the test results.

[0040] In the S1 raw material pretreatment step, the polyol is dried at a drying temperature of 120°C for 2-4 hours to ensure that the water content of the raw material polyol drops below 0.05%. In the S2 prepolymer synthesis step, the raw material includes two components, which are marked as component A and component B respectively. Component A includes polyether polyol and polyester polyol, and component B is isocyanate. The polyether polyol and polyester polyol in component A are mixed into a polyol mixture. The polyol mixture is divided into two parts, one of which is mixed with the isocyanate of component B to generate a prepolymer. In the S3 foaming and molding step, the prepolymer generated by the mixture is mixed with the other part of the polyol mixture, and triethylamine catalyst, ethylenediamine chain extender, calcium carbonate filler and carbon dioxide foaming agent are added to generate a raw material mixture. The raw material mixture is injected into a mold, heated and cured to generate a polishing pad product. The ethylamine catalyst promotes the reaction between isocyanate and polyol. The ethylenediamine chain extender reacts with the isocyanate end group in the prepolymer to increase the molecular weight of the polyurethane. The calcium carbonate filler can increase the overall density of the foamed polyurethane. In the S4 demoulding and post-processing step, the solidified polishing pad is cooled to room temperature for demoulding. The demoulding polishing pad is trimmed, and the trimming operation includes cutting and grinding to obtain a polishing pad of a desired size. The trimmed polishing pad is coated with a layer of silicone coating, and the silicone coating improves the hardness and wear resistance of the polishing pad surface. The reaction temperature in steps S1 to S5 increases in a gradient, the temperature in the raw material mixing stage is 20°C-30°C, the temperature in the prepolymer and foaming stage is 30°C-50°C, and the temperature in the curing stage is 50°C-80°C. The reaction in each stage is preheated to increase the temperature slowly.

[0041] like Figure 2 and Figure 3As shown, the polyol is dried at 120° C. for 2-4 hours to reduce the water content in the raw polyol to below 0.05%, so as to prevent the water in the raw polyol from affecting the subsequent polymerization reaction process. The polyether polyol and the polyester polyol are mixed into a polyol mixture, and part of the polyol mixture is reacted with isocyanate to generate a prepolymer. The generated prepolymer is subjected to a secondary reaction with the remaining polyol mixture. The prepolymer generation process makes the polishing pad react relatively mildly during the preparation process and is easy to control, so as to obtain a polymer with more stable performance. In the secondary reaction process of the prepolymer and the polyol mixture, triethylamine catalyst, ethylenediamine chain extender, Calcium carbonate filler and carbon dioxide foaming agent, triethylamine catalyst accelerate the reaction process, ethylenediamine chain extender can react with the isocyanate end group in the prepolymer to increase the molecular weight of the polyurethane. The increase in molecular weight can improve the mechanical properties of the finished polishing pad, and the calcium carbonate filler increases the overall density of the foamed polyurethane. The mixed raw materials are injected into the mold and cured by gradient heating to reduce the time that the reaction system is in an unstable state and improve the quality and performance of the product. After curing, the product is demolded, and the demolded product is cut and polished to obtain a finished product of a specific size, and a silicone coating is applied on the surface to increase the performance of the finished product.

[0042] In the S5 sheet inspection and formula optimization step, the hardness and density of the finished polishing pad are tested, and the raw material mixing ratio is adjusted accordingly according to the test results. The adjustment method is as follows: increase the amount of isocyanate to improve the density and hardness of the polishing pad, and the increase in isocyanate is 10%-20%; reduce the amount of polyol, when the amount of polyol is reduced, the isocyanate content in the reaction increases accordingly, thereby improving the density and hardness of the polishing pad; reduce the amount of foaming agent, the reduction of foaming agent will reduce the size and number of pores in the polishing pad, make the structure of the polyurethane polymer more compact, and improve the density and hardness;

[0043] The hardness and density data of the prepared polishing pad are tested, and the content of each component in the raw material is adjusted accordingly based on the test results. Among them, increasing the isocyanate content, reducing the polyol content, and reducing the amount of foaming agent can all improve the density and hardness of the polyurethane polymer, thereby increasing the performance of the finished polishing pad.

[0044] Working principle: Before the reaction starts, the raw material polyether polyol and polyester polyol are dried at 120°C to reduce the water content to below 0.05%, so as to avoid the water in the raw material polyol affecting the subsequent reaction process. The dried polyether polyol and polyester polyol are mixed into a polyol mixture, one part of which reacts with isocyanate to form a prepolymer, and the other part undergoes a secondary reaction with the generated prepolymer, and triethylamine catalyst, ethylenediamine chain extender, calcium carbonate filler and carbon dioxide foaming agent are added. The generation of the prepolymer can make the reaction relatively warm during the entire preparation process of the polishing pad. The degree is easy to control, so that a more stable polymer can be obtained. The triethylamine catalyst can accelerate the reaction process. The ethylenediamine chain extender can react with the isocyanate end group in the prepolymer to increase the molecular weight of the polyurethane, thereby improving the mechanical properties of the finished polishing pad. The calcium carbonate filler increases the overall density of the foamed polyurethane. The mixed raw materials are injected into the mold, heated and cured, and after curing, cooled to room temperature and demolded. The demolded product is cut and polished, and a silicone coating is applied on the surface to increase the performance of the finished product, thereby obtaining a high-density and high-hardness foamed polyurethane polishing pad.

[0045] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a high-density and high-hardness foamed polyurethane polishing pad, characterized in that: The following steps are involved: S1. Raw material pretreatment step, drying the synthetic raw materials to avoid moisture affecting the polymerization process; S2. prepolymer synthesis step, in which part of the mixed polyol is pre-reacted with isocyanate to form a prepolymer, and the prepolymer is reacted and mixed with the remaining polyol again and an auxiliary reagent is added; S3 foaming and molding step, the mixed raw materials are injected into the mold, foaming and curing; S4 demolding and post-processing steps, the raw material after molding is removed from the mold to obtain a finished polishing pad, the polishing pad is surface treated to obtain the final product; S5. The step of tablet inspection and formula optimization is to inspect the hardness and density of the finished polishing pad after treatment, and adjust the raw material mixing ratio accordingly according to the inspection results.

2. The method for preparing a high-density and high-hardness foamed polyurethane polishing pad according to claim 1, characterized in that: In the raw material pretreatment step S1, the polyol is dried at a drying temperature of 120° C. for 2-4 hours to ensure that the water content of the raw material polyol drops below 0.05%.

3. The method for preparing a high-density and high-hardness foamed polyurethane polishing pad according to claim 1, characterized in that: The raw materials in the S2 prepolymer synthesis step include two components, respectively marked as component A and component B, the component A includes polyether polyol and polyester polyol, the component B is isocyanate, the polyether polyol and polyester polyol in component A are mixed into a polyol mixture, and the polyol mixture is divided into two parts, one of which is mixed with the isocyanate of component B to form a prepolymer.

4. The method for preparing a high-density and high-hardness foamed polyurethane polishing pad according to claim 1, characterized in that: In the S3 foaming and molding step, the prepolymer is mixed with another part of the polyol mixture, and triethylamine catalyst, ethylenediamine chain extender, calcium carbonate filler and carbon dioxide foaming agent are added to generate a raw material mixture, which is injected into a mold and heated and cured to generate a polishing pad product.

5. The method for preparing a high-density and high-hardness foamed polyurethane polishing pad according to claim 4, characterized in that: The triethylamine catalyst promotes the reaction between isocyanate and polyol, the ethylenediamine chain extender reacts with the isocyanate end groups in the prepolymer to increase the molecular weight of the polyurethane, and the calcium carbonate filler can increase the overall density of the foamed polyurethane.

6. The method for preparing a high-density and high-hardness foamed polyurethane polishing pad according to claim 1, characterized in that: In the S4 demolding and post-processing step, the solidified polishing pad is cooled to room temperature for demolding, and the demolded polishing pad is trimmed, which includes cutting and grinding to obtain a polishing pad of a desired size. The trimmed polishing pad is coated with a layer of silicone coating, which improves the hardness and wear resistance of the polishing pad surface.

7. The method for preparing a high-density and high-hardness foamed polyurethane polishing pad according to claim 1, characterized in that: In the S5 tableting inspection and formula optimization step, the hardness and density of the finished polishing pad are inspected, and the raw material mixing ratio is adjusted accordingly according to the inspection results. The adjustment method is as follows: Increasing the amount of isocyanate to improve the density and hardness of the polishing pad, wherein the amount of isocyanate increased is 10%-20%; Reducing the amount of polyols used. When the amount of polyols used is reduced, the isocyanate content in the reaction increases accordingly, thereby increasing the density and hardness of the polishing pad; The amount of foaming agent used is reduced, which reduces the size and number of cells in the polishing pad, makes the structure of the polyurethane polymer more compact, and increases the density and hardness.

8. The method for preparing a high-density and high-hardness foamed polyurethane polishing pad according to claim 1, characterized in that: The reaction temperature in steps S1 to S5 increases in a gradient manner. The temperature in the raw material mixing stage is 20°C-30°C, the temperature in the prepolymer and foaming stage is 30°C-50°C, and the temperature in the curing stage is 50°C-80°C. The reactions in each stage are preheated to increase the temperature gradually.

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