Preparation method of solvent-free polyurethane grinding pad with color change monitoring function

Abstract

The invention provides a preparation method of a solvent-free polyurethane grinding pad with a discoloration monitoring function, which comprises the following steps: dissolving a PH indicator, an emulsifier and a chain extender in deionized water to prepare a water phase, dissolving a wall material monomer in an organic solvent to prepare an oil phase, and adding an amino silicon oil coupling agent; adding the water phase into the oil phase, and carrying out emulsification and interfacial polymerization reaction to obtain a PH indicator microcapsule; taking a component A, namely polyol, a filler, a catalyst and a PH indicator microcapsule; the preparation method comprises the following steps: firstly, adding the filler into component A polyhydric alcohol for mixing, then adding the catalyst for mixing, and finally adding the PH indicator microcapsule to obtain a material A; taking isocyanate of a component B as a material B; in the presence of supercritical CO2 fluid, stirring and mixing the material A and the material B to obtain a mixture; and heating, curing, cooling, separating the release paper and cutting to obtain the solvent-free polyurethane grinding pad. The breakage rate of the microcapsules is reduced, and the microcapsules are dispersed uniformly without agglomeration.

Description

Technical Field

[0001] This invention relates to a method for preparing a polyurethane abrasive pad, specifically a method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function, belonging to the field of polyurethane material technology. Background Technology

[0002] Chemical mechanical polishing (CMP) is a key process for planarizing semiconductor wafer surfaces, and the polishing pad, as a core consumable in CMP, directly determines the polishing effect. With increased usage time, the surface of the polishing pad wears down, leading to shallower trenches and reduced polishing slurry transfer capacity, thus affecting wafer yield. Therefore, timely and accurate assessment of the polishing pad's wear level and timely replacement are crucial. Existing polishing pad lifetime monitoring mainly relies on offline measurements or empirical estimations, lacking intuitive real-time monitoring methods. Although existing technologies include adding dyes or indicators to the polishing pad, directly mixed dyes cannot reflect the depth of wear. To address this issue, microencapsulation technology has been introduced, attempting to indicate wear by encapsulating a pH indicator; during polishing, the microcapsules rupture and change color upon contact with alkaline / acidic polishing slurries. However, applying microencapsulation technology to the preparation of solvent-free polyurethane polishing pads typically faces challenges in simultaneously achieving microcapsule dispersibility and low breakage, as well as poor interfacial adhesion between the microcapsule wall material and the solvent-free polyurethane matrix.

[0003] Solvent-free polyurethane components, especially polyol A, have high viscosity, typically exceeding 2000 cps. To ensure uniform dispersion of microcapsules in the matrix, high-shear mechanical stirring is usually required. However, the micron-sized microcapsule walls are thin and brittle, and high shear forces can easily cause microcapsules to rupture and fail during the mixing stage, resulting in discoloration or loss of monitoring function in the finished grinding pad before use. Reducing the stirring speed can lead to microcapsule agglomeration, resulting in uneven grinding pad performance. Interface defects often exist between the microcapsule wall material and the solvent-free polyurethane matrix. During the high-intensity shear grinding process of CMP, weak interfacial bonding can cause microcapsules to detach entirely, forming large pits. This not only results in loss of indication function but also the potential for detached particles to scratch the wafer surface. Summary of the Invention

[0004] Based on the above background, the purpose of this invention is to provide a method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function. By introducing amino silicone oil interface modification and utilizing the plasticizing and viscosity-reducing effect of supercritical fluid, the uniform dispersion of microcapsules in a solvent-free system is achieved while ensuring the structural integrity of the microcapsules, thus solving the problems of easy breakage of microcapsules and poor bonding force with the matrix in the prior art.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function, the method comprising the following steps:

[0007] S1. The pH indicator, emulsifier, and chain extender are dissolved in deionized water to prepare an aqueous phase. The wall material monomer is dissolved in an organic solvent to prepare an oil phase. An amino silicone oil coupling agent is added to the oil phase or the aqueous phase. Under shear conditions, the aqueous phase is added to the oil phase to carry out emulsification and interfacial polymerization reaction. After curing, washing, and drying, pH indicator microcapsules are obtained.

[0008] S2. By weight, take 100 parts of polyol of component A, 0-30 parts of filler, 0.01-1 parts of catalyst and 1-20 parts of pH indicator microcapsules prepared in step S1; first add filler to polyol of component A and mix, then add catalyst and mix, and finally add pH indicator microcapsules and disperse evenly under mechanical stirring to obtain material A.

[0009] S3. By weight, take 50-120 parts of isocyanate component B as material B; feed material A and material B to the mixer head respectively, and at the same time, feed supercritical CO2 fluid into the mixer head in a predetermined ratio. Under the condition of supercritical CO2 fluid, stir and mix material A and material B to obtain a mixture.

[0010] S4. The mixture obtained in step S3 is coated onto release paper, heated and cured, cooled, the release paper is separated and cut to obtain the solvent-free polyurethane abrasive pad.

[0011] Step S1 introduces an amino silicone oil coupling agent to participate in interfacial polymerization, resulting in organosilicon segments and active amino groups on the surface of the microcapsules. This improves the dispersibility of the microcapsules in the subsequent polyurethane matrix and enhances the interfacial bonding force through chemical bonding. Step S2 employs a stepwise feeding method, first dispersing the difficult-to-disperse inorganic fillers, and finally adding the microcapsules. Pre-dispersion is controlled only during the A-component stage to avoid prolonged high-shear damage to the microcapsules. Step S3 utilizes the low viscosity and high diffusivity of supercritical CO2 fluid, which dissolves in the polyurethane prepolymer, significantly reducing the system viscosity. This allows the mixing of A / B components to achieve molecular-level homogeneous mixing at a lower shear rate, thus protecting the integrity of the microcapsule walls and resolving the contradiction between the high shear required for high-viscosity mixing and the fragility of the microcapsules. Step S4 completes the final molding.

[0012] Preferably, in step S1, the aqueous phase is prepared as follows: 100 parts by weight of deionized water, 0.5-5 parts by weight of pH indicator, and 0.1-5 parts by weight of emulsifier; the pH indicator is selected from one or more of phenolphthalein, methyl red, and bromothymol blue; the chain extender is selected from at least one of diethyldiamine and diethylenetriamine, and the molar ratio of the chain extender to the wall material monomer is 1:1-1:1.5.

[0013] Preferably, in step S1, the oil phase is prepared in the following proportions: 100 parts by weight of organic solvent and 5-20 parts by weight of wall material monomer; the wall material monomer is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, and isophorone diisocyanate.

[0014] Preferably, in step S1, the amount of amino silicone oil coupling agent added is 0.1-2 parts by weight.

[0015] This range ensures sufficient interface modification while avoiding excessive silicone oil from affecting the compactness of the microcapsule wall.

[0016] Preferably, in step S1, the process conditions for the emulsification and interfacial polymerization reaction are as follows: first, shear emulsification is performed at a speed of 2000-6000 rpm to form a water-in-oil emulsion, and then the speed is reduced to 200-500 rpm, and the polymerization reaction is carried out at a temperature of 65-70°C for 2-3 hours.

[0017] Segmented speed control: high shear in the early stage ensures small and uniform particle size, while low shear polymerization in the later stage prevents the rupture of the formed capsule walls.

[0018] Preferably, in step S2, the polyol of component A is selected from polyether polyol or polyester polyol; the filler is selected from one or more of the following: matting powder, aluminum hydroxide, aluminum oxide, magnesium hydroxide, zinc borate, aluminum silicate, magnesium carbonate, glass microspheres, silica, organosilicon resin powder, silicon dioxide, calcium carbonate, magnesium oxide, cerium oxide, and zirconium oxide.

[0019] Preferably, in step S2, the mechanical stirring conditions after adding the pH indicator microcapsules are: 300-600 rpm and 10-20 minutes.

[0020] Strictly limit the stirring speed to a low level, relying solely on mechanical force for macroscopic dispersion to avoid microcapsule breakage.

[0021] Preferably, in step S3, the isocyanate component B is diphenylmethane diisocyanate.

[0022] Preferably, in step S4, the coating amount is controlled at 100-300 g / m². 2 The viscosity of the mixture is 2000-10000 cps at 25°C.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] This invention discloses a method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function. By introducing an amino silicone oil coupling agent in situ during the microcapsule preparation stage, silicon-containing hydrophobic segments and active reactive groups are constructed on the surface of the microcapsules. During the curing process of the abrasive pad, the microcapsules are firmly anchored in the polyurethane matrix through chemical bonds, effectively preventing the microcapsules from falling off during the abrasive process. Furthermore, by introducing a supercritical fluid-assisted mixing process, the swelling and plasticizing effects of supercritical fluid in the polyurethane components are utilized to significantly reduce the viscosity of the reaction system. This allows the mixing of components A / B with the microcapsules to be completed under a low shear field, reducing the breakage rate of the microcapsules and ensuring uniform dispersion without agglomeration. Detailed Implementation

[0025] The technical solution of the present invention will be further described in detail below through specific embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.

[0026] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art. Unless otherwise specified, the components or equipment in the following embodiments are general standard parts or components known to those skilled in the art, and their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0027] The embodiments of the present invention are described in detail below. In this detailed description, many specific details are set forth to facilitate explanation and provide a thorough understanding of the embodiments of the present invention. However, one or more embodiments may be practiced by those skilled in the art without these specific details.

[0028] Example 1

[0029] A method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function includes the following steps:

[0030] S1, Microcapsule Preparation

[0031] Aqueous phase: 100g deionized water, 3g phenolphthalein (pH indicator), 2g OP-10 (emulsifier), and hexamethylenediamine (chain extender) in a molar ratio of 1:1.2 to the wall material.

[0032] Oil phase: 100g xylene, 15g toluene diisocyanate (TDI, wall material monomer), 1g amino silicone oil coupling agent.

[0033] Process: The aqueous phase was added to the oil phase at 4000 rpm for emulsification, then the speed was reduced to 300 rpm and reacted at 68°C for 2.5 hours. After washing and drying, microcapsules were obtained.

[0034] S2, Preparation of Material A

[0035] Raw materials: 100 parts of polyether polyol, 15 parts of silica filler, 0.5 parts of amine catalyst, and 10 parts of microcapsules obtained in step S1.

[0036] Process: First, mix in the filler, then add the catalyst, and finally add the microcapsules. After adding the microcapsules, the stirring speed is 450 rpm, and the stirring time is 15 minutes.

[0037] S3, Supercritical Fluid Mixing

[0038] Material B: 85 parts of diphenylmethane diisocyanate (MDI).

[0039] Process: Materials A and B are fed to the mixer head, and supercritical CO2 is injected simultaneously. Process conditions: Temperature 35℃, pressure 8.0MPa, mixer head speed 4000rpm.

[0040] S4, Molding

[0041] Coating amount 200g / m 2 The product is obtained by aging at 135℃ for 10 minutes.

[0042] Example 2

[0043] A method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function includes the following steps:

[0044] S1, Microcapsule Preparation

[0045] Aqueous phase: 100g deionized water, 0.5g phenolphthalein (pH indicator), 0.1g OP-10 (emulsifier), and hexamethylenediamine (chain extender) in a molar ratio of 1:1.2 to the wall material.

[0046] Oil phase: 100g xylene, 5g toluene diisocyanate (TDI, wall material monomer), 0.1g amino silicone oil coupling agent.

[0047] Process: The aqueous phase was added to the oil phase at 2000 rpm for emulsification, then the speed was reduced to 200 rpm and reacted at 68°C for 2.5 hours. After washing and drying, microcapsules were obtained.

[0048] S2, Preparation of Material A

[0049] Raw materials: 100 parts of polyether polyol, 0.01 parts of amine catalyst, and 1 part of the microcapsules obtained in step S1.

[0050] Process: First, mix in the filler, then add the catalyst, and finally add the microcapsules. After adding the microcapsules, the stirring speed is 300 rpm, and the stirring time is 10 minutes.

[0051] S3, Supercritical Fluid Mixing

[0052] Material B: 50 parts of diphenylmethane diisocyanate (MDI).

[0053] Process: Materials A and B are fed to the mixer head, and supercritical CO2 is injected simultaneously. Process conditions: Temperature 31.5℃, pressure 7.5MPa, mixer head speed 4000rpm.

[0054] S4, Molding

[0055] Coating amount 100g / m 2 The product is obtained by aging at 135℃ for 10 minutes.

[0056] Example 3

[0057] A method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function includes the following steps:

[0058] S1, Microcapsule Preparation

[0059] Aqueous phase: 100g deionized water, 5g phenolphthalein (pH indicator), 5g OP-10 (emulsifier), and hexamethylenediamine (chain extender) in a molar ratio of 1:1.2 to the wall material.

[0060] Oil phase: 100g xylene, 20g toluene diisocyanate (TDI, wall material monomer), 2g amino silicone oil coupling agent.

[0061] Process: The aqueous phase was added to the oil phase at 6000 rpm for emulsification, then the speed was reduced to 500 rpm and reacted at 68°C for 2.5 hours. After washing and drying, microcapsules were obtained.

[0062] S2, Preparation of Material A

[0063] Raw materials: 100 parts polyether polyol, 30 parts silica filler, 1 part amine catalyst, and 20 parts microcapsules obtained in step S1.

[0064] Process: First, mix in the filler, then add the catalyst, and finally add the microcapsules. After adding the microcapsules, the stirring speed is 600 rpm, and the stirring time is 20 minutes.

[0065] S3, Supercritical Fluid Mixing

[0066] Material B: 120 parts of diphenylmethane diisocyanate (MDI).

[0067] Process: Materials A and B are fed to the mixer head, and supercritical CO2 is injected simultaneously. Process conditions: Temperature 40℃, pressure 10MPa, mixer head speed 4000rpm.

[0068] S4, Molding

[0069] Coating amount 300g / m 2 The product is obtained by aging at 135℃ for 10 minutes.

[0070] Comparative Example 1

[0071] A method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function includes the following steps:

[0072] S1, Microcapsule Preparation

[0073] Aqueous phase: 100g deionized water, 3g phenolphthalein (pH indicator), 2g OP-10 (emulsifier), and hexamethylenediamine (chain extender) in a molar ratio of 1:1.2 to the wall material.

[0074] Oil phase: 100g xylene, 15g toluene diisocyanate (TDI, wall material monomer), 1g amino silicone oil coupling agent.

[0075] Process: The aqueous phase was added to the oil phase at 4000 rpm for emulsification, then the speed was reduced to 300 rpm and reacted at 68°C for 2.5 hours. After washing and drying, microcapsules were obtained.

[0076] S2, Preparation of Material A

[0077] Raw materials: 100 parts polyether polyol, 15 parts silica filler, 0.5 parts amine catalyst, and 10 parts microcapsules obtained in step S1.

[0078] Process: First, mix in the filler, then add the catalyst, and finally add the microcapsules. After adding the microcapsules, the stirring speed is 450 rpm, and the stirring time is 15 minutes.

[0079] S3, Supercritical fluid mixing

[0080] Material B: 85 parts of diphenylmethane diisocyanate (MDI).

[0081] Process: Material A and Material B are fed to the mixer head, which rotates at 20,000 rpm.

[0082] S4, Molding

[0083] Coating amount 200g / m 2 The product is obtained by aging at 135℃ for 10 minutes.

[0084] Comparative Example 2

[0085] A method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function includes the following steps:

[0086] S1, Microcapsule Preparation

[0087] Aqueous phase: 100g deionized water, 3g phenolphthalein (pH indicator), 2g OP-10 (emulsifier), and hexamethylenediamine (chain extender) in a molar ratio of 1:1.2 to the wall material.

[0088] Oil phase: 100g xylene, 15g toluene diisocyanate (TDI, wall material monomer).

[0089] Process: The aqueous phase was added to the oil phase at 4000 rpm for emulsification, then the speed was reduced to 300 rpm and reacted at 68°C for 2.5 hours. After washing and drying, microcapsules were obtained.

[0090] S2, Preparation of Material A

[0091] Raw materials: 100 parts polyether polyol, 15 parts silica filler, 0.5 parts amine catalyst, and 10 parts microcapsules obtained in step S1.

[0092] Process: First, mix in the filler, then add the catalyst, and finally add the microcapsules. After adding the microcapsules, the stirring speed is 450 rpm, and the stirring time is 15 minutes.

[0093] S3, Supercritical fluid mixing

[0094] Material B: 85 parts of diphenylmethane diisocyanate (MDI).

[0095] Process: Materials A and B are fed to the mixer head, and supercritical CO2 is injected simultaneously. Process conditions: Temperature 35℃, pressure 8.0MPa, mixer head speed 4000rpm.

[0096] S4, Molding

[0097] Coating amount 200g / m 2 The product is obtained by aging at 135℃ for 10 minutes.

[0098] Comparative Example 3

[0099] A method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function includes the following steps:

[0100] S1, Microcapsule Preparation

[0101] Aqueous phase: 100g deionized water, 3g phenolphthalein (pH indicator), 2g OP-10 (emulsifier), and hexamethylenediamine (chain extender) in a molar ratio of 1:1.2 to the wall material.

[0102] Oil phase: 100g xylene, 15g toluene diisocyanate (TDI, wall material monomer), 1g amino silicone oil coupling agent.

[0103] Process: The aqueous phase was added to the oil phase at 4000 rpm for emulsification, then the speed was reduced to 300 rpm and reacted at 68°C for 2.5 hours. After washing and drying, microcapsules were obtained.

[0104] S2, Preparation of Material A

[0105] Raw materials: 100 parts of polyether polyol, 15 parts of silica filler, 0.5 parts of amine catalyst, and 10 parts of microcapsules obtained in step S1.

[0106] Process: First, mix in the filler, then add the catalyst, and finally add the microcapsules. After adding the microcapsules, the stirring speed is 2000 rpm, and the stirring time is 15 minutes.

[0107] S3, Supercritical Fluid Mixing

[0108] Material B: 85 parts of diphenylmethane diisocyanate (MDI).

[0109] Process: Materials A and B are fed to the mixer head, and supercritical CO2 is injected simultaneously. Process conditions: Temperature 35℃, pressure 8.0MPa, mixer head speed 4000rpm.

[0110] S4, Molding

[0111] Coating amount 200g / m 2 The product is obtained by aging at 135℃ for 10 minutes.

[0112] The performance of the abrasive pad samples prepared in the above embodiments and comparative examples was tested, and the results are shown in Table 1.

[0113] Table 1 Comparison of performance test results of abrasive pad samples from Examples 1-3 and Comparative Examples 1-3 Testing items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Microcapsule breakage rate % 0.3% 0.5% 0.8% 45.2% 0.4% 38.6% Color change response time (s) 2 3 2 >60 2 >45 Taber wear rate % 0.35% 0.40% 0.32% 0.48% 0.85% 0.52% Surface defects none none none - Severe shedding - Hardness Shore A 65 55 85 62 58 63

[0114] The microcapsule breakage rate test involves taking a slurry coating after mixing and counting the number of broken and deformed microcapsules out of 1000 microcapsules under a microscope. The color change response time test is performed by simulating grinding, adding an alkaline solution with pH=10, and recording the color change time. The Taber abrasion resistance test measures the mass loss rate after 5000 revolutions of wear. The surface defect test involves observing the surface after grinding for pits left by microcapsule detachment.

[0115] Comparative data shows that the microcapsule breakage rate in Comparative Example 1 was as high as 45.2%, leading to the failure of the color-changing response. This is because, without supercritical CO2, the viscosity of the A / B mixture is high, exceeding 5000 cps, requiring greater mechanical shear force to achieve homogeneous mixing, which exceeds the tolerance limit of the microcapsule wall. In contrast, Example 1 uses supercritical CO2, whose molecules insert into the polymer chain segments, increasing the free volume and causing the system viscosity to decrease exponentially. This transforms the mixing process from shear-dominated to diffusion-dominated, achieving homogeneous mixing under low fluid shear stress while preserving the structural integrity of the microcapsules, with a breakage rate of only 0.3%.

[0116] Although the microcapsules in Comparative Example 2 remained intact, they exhibited a high wear rate and significant surface detachment. This was because the ordinary polyurea wall material was only bonded to the polyurethane matrix by weak van der Waals forces. In Example 1, the amino groups of the amino silicone oil participated in the curing reaction of the microcapsule wall, while its long-chain siloxane segments extended into the matrix. During the curing of the polishing pad, the active groups on the microcapsule surface reacted chemically with the isocyanates in the matrix, forming a dual anchoring effect of chemical bonding and physical entanglement. This prevented the microcapsules from peeling off entirely during polishing, instead allowing them to wear synchronously with the matrix, thus ensuring the wear resistance and surface smoothness of the polishing pad.

[0117] Comparative Example 3 shows that even if supercritical CO2 is used subsequently, if high shear is used in the premixing stage of material A, the microcapsules will still break down in large quantities, which verifies the necessity of low-speed stirring in the premixing stage of material A.

[0118] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function, characterized in that: The method includes the following steps: S1. The pH indicator, emulsifier, and chain extender are dissolved in deionized water to prepare an aqueous phase. The wall material monomer is dissolved in an organic solvent to prepare an oil phase. An amino silicone oil coupling agent is added to the oil phase or the aqueous phase. Under shear conditions, the aqueous phase is added to the oil phase to carry out emulsification and interfacial polymerization reaction. After curing, washing, and drying, pH indicator microcapsules are obtained. S2. By weight, take 100 parts of polyol of component A, 0-30 parts of filler, 0.01-1 parts of catalyst and 1-20 parts of pH indicator microcapsules prepared in step S1; first add filler to polyol of component A and mix, then add catalyst and mix, and finally add pH indicator microcapsules and disperse evenly under mechanical stirring to obtain material A. S3. By weight, take 50-120 parts of isocyanate component B as material B; feed material A and material B to the mixer head respectively, and at the same time, feed supercritical CO2 fluid into the mixer head in a predetermined ratio. Under the condition of supercritical CO2 fluid, stir and mix material A and material B to obtain a mixture. S4. The mixture obtained in step S3 is coated onto release paper, heated and cured, cooled, the release paper is separated and cut to obtain the solvent-free polyurethane abrasive pad.

2. The method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function according to claim 1, characterized in that: In step S1, the aqueous phase is prepared as follows: 100 parts by weight of deionized water, 0.5-5 parts by weight of pH indicator, and 0.1-5 parts by weight of emulsifier; the pH indicator is selected from one or more of phenolphthalein, methyl red, and bromothymol blue; the chain extender is selected from at least one of diethyldiamine and diethylenetriamine, and the molar ratio of the chain extender to the wall material monomer is 1:1-1:1.

5.

3. The method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function according to claim 1, characterized in that: In step S1, the oil phase is formulated as follows: 100 parts by weight of organic solvent and 5-20 parts by weight of wall material monomer; the wall material monomer is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, and isophorone diisocyanate.

4. The method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function according to claim 1, characterized in that: In step S1, the amount of amino silicone oil coupling agent added is 0.1-2 parts by weight.

5. The method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function according to claim 1, characterized in that: In step S1, the process conditions for the emulsification and interfacial polymerization reaction are as follows: first, shear emulsification is performed at a speed of 2000-6000 rpm to form a water-in-oil emulsion, and then the speed is reduced to 200-500 rpm, and the polymerization reaction is carried out at a temperature of 65-70℃ for 2-3 hours.

6. The method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function according to claim 1, characterized in that: In step S2, the polyol in component A is selected from polyether polyol or polyester polyol; the filler is selected from one or more of the following: matting powder, aluminum hydroxide, aluminum oxide, magnesium hydroxide, zinc borate, aluminum silicate, magnesium carbonate, glass microspheres, silica, organosilicon resin powder, silicon dioxide, calcium carbonate, magnesium oxide, cerium oxide, and zirconium oxide.

7. The method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function according to claim 1, characterized in that: In step S2, the mechanical stirring conditions after adding the pH indicator microcapsules are: rotation speed 300-600 rpm, stirring time 10-20 minutes.

8. The method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function according to claim 1, characterized in that: In step S3, the isocyanate component B is diphenylmethane diisocyanate.

9. The method for preparing a solvent-free polyurethane abrasive pad with color change monitoring function according to claim 1, characterized in that: In step S4, the coating amount is controlled at 100-300 g / m². 2 The viscosity of the mixture is 2000-10000 cps at 25°C.