A melamine resin / polyurethane composite polishing pad and its preparation method

Abstract

The invention discloses a melamine resin / polyurethane composite polishing pad and a preparation method thereof. The method comprises the following steps: 1. preparing a modified porous melamine resin: S1. adding an organic modifier into a first solvent and stirring the mixture uniformly to obtain a modified solution; S2. immersing the porous melamine resin into the modified solution for reaction, taking out the product after the reaction and drying it to obtain the modified porous melamine resin; 2. preparing a melamine resin / polyurethane composite polishing pad: S1. adding polyurethane into a second solvent and stirring the mixture uniformly to obtain a polyurethane solution; S2. immersing the modified porous melamine resin into the polyurethane solution for reaction to obtain a porous melamine resin / polyurethane composite; S3. immersing the porous melamine resin / polyurethane composite into an aqueous solution of the second solvent for flocculation reaction, while freezing the composite; after returning the composite to room temperature, washing, drying, grinding, and cutting the product to obtain the melamine resin / polyurethane composite polishing pad.

Description

Technical Field

[0001] The invention relates to the technical field of polymer composite materials, and in particular to a melamine resin / polyurethane composite polishing pad and a preparation method thereof. Background Art

[0002] Polishing pads are essential consumables in chemical mechanical polishing (CMP) systems, storing and transporting polishing fluid, removing waste, transferring process loads, and ensuring a smooth polishing process. Their cost accounts for approximately one-third of the total cost of CMP. Polyurethane is widely used as a polishing pad substrate due to its heat and wear resistance, as well as its excellent liquid-holding properties. However, its inherent structural characteristics have drawbacks such as low hardness and poor wear resistance.

[0003] To address this issue, polyurethane polishing pads are currently manufactured using a solvent-nonsolvent flocculation process. This process increases the hardness of the product by increasing the polyurethane loading, but this also significantly reduces the porosity of the polishing pad, significantly impacting the polishing accuracy and service life of the polyurethane polishing pad. These polyurethane polishing pads are typically treated with methods such as rapid heat treatment, mechanical grooving, and drilling to increase their porosity. However, these processes are not only complex and wasteful of raw materials, but also further degrade the mechanical properties of the product. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the polyurethane polishing pads prepared by the current process and provide a method for preparing a melamine resin / polyurethane composite polishing pad. The polishing pad prepared by the method of the present invention solves the problem of poor compatibility between hardness and porosity of the current polyurethane polishing pads, and effectively improves the hardness and porosity of the polyurethane polishing pads.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that the method comprises the following steps:

[0007] 1. Preparation of modified porous melamine resin:

[0008] S1, adding an organic modifier to a first solvent and stirring uniformly to obtain a modified solution;

[0009] S2, immersing the porous melamine resin in the modification solution to react, taking out the product after the reaction and drying it to obtain a modified porous melamine resin;

[0010] 2. Preparation of melamine resin / polyurethane composite polishing pad:

[0011] S1, adding polyurethane to the second solvent and stirring evenly to obtain a polyurethane solution;

[0012] S2, impregnating the modified porous melamine resin in the polyurethane solution to react, thereby preparing a porous melamine resin / polyurethane composite;

[0013] S3. Immersing the porous melamine resin / polyurethane composite in an aqueous solution of the second solvent for flocculation (precipitation) reaction, while freezing the composite. After returning to room temperature, the composite is washed, dried, ground, and cut to obtain a melamine resin / polyurethane composite polishing pad.

[0014] Specifically, in the method of the present invention, the organic modifier is chemically bonded with the amino groups on the inner and outer pore surfaces of the porous melamine resin by immersion modification, which is conducive to the uniform chemical adsorption of the organic modifier on the surface of the porous melamine resin; at the same time, the organic modifier adsorbed on the surface of the porous melamine resin will further undergo a chemical grafting reaction with the polyurethane, so that the polyurethane resin is uniformly assembled and wrapped on the surface of the porous melamine resin. Then, a large number of micropores formed during the coagulation and foaming process of the polyurethane form a pore-pore interconnected structure with the micropores and nanopores existing in the porous melamine resin itself, effectively increasing the bubble density of the obtained porous melamine resin / polyurethane composite material.

[0015] Furthermore, a method for preparing a melamine resin / polyurethane composite polishing pad is provided: 1. Preparation of modified porous melamine resin:

[0016] In step S1, the organic modifier is isocyanate; the first solvent is acetone; and the mass ratio of the organic modifier to the first solvent is (0.05-0.2):1.

[0017] Furthermore, a method for preparing a melamine resin / polyurethane composite polishing pad is provided: the isocyanate is selected from any one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, and meta-xylylenediisocyanate.

[0018] Furthermore, a method for preparing a melamine resin / polyurethane composite polishing pad is provided: 1. Preparation of modified porous melamine resin:

[0019] Step S2, immersing the porous melamine resin in the modified solution and performing an adsorption reaction at 60-80° C., while condensing and recovering the first solvent until the first solvent is completely evaporated, taking out the product after the reaction and drying it to obtain a modified porous melamine resin;

[0020] Wherein: the mass ratio of the porous melamine resin to the organic modifier is 1:(0.02-0.05).

[0021] Furthermore, a method for preparing a melamine resin / polyurethane composite polishing pad is provided: 2. Preparation of a melamine resin / polyurethane composite polishing pad:

[0022] In step S1, the second solvent is N,N-dimethylformamide (DMF);

[0023] The mass fraction of polyurethane in the polyurethane solution in step S1 is 5.0% to 20.0%.

[0024] Furthermore, a method for preparing a melamine resin / polyurethane composite polishing pad is provided: 2. Preparation of a melamine resin / polyurethane composite polishing pad:

[0025] The molecular weight of the polyurethane in step S1 is 30,000 to 50,000.

[0026] Furthermore, a method for preparing a melamine resin / polyurethane composite polishing pad is provided: 2. Preparation of a melamine resin / polyurethane composite polishing pad:

[0027] The mass ratio of the modified porous melamine resin to the polyurethane in step S2 is (0.1-0.5):1; and the reaction time in step S2 is 1-3 hours.

[0028] Furthermore, a method for preparing a melamine resin / polyurethane composite polishing pad is provided: 2. Preparation of a melamine resin / polyurethane composite polishing pad:

[0029] The volume concentration of the aqueous solution of the second solvent in step S3 is 10.0% to 25.0%;

[0030] The freezing temperature in step S3 is -20°C to -10°C, and the freezing time is 3 to 6 hours.

[0031] A melamine resin / polyurethane composite polishing pad is characterized in that the melamine resin / polyurethane composite polishing pad is prepared by the above-mentioned preparation method.

[0032] Beneficial effects of the present invention:

[0033] (1) The preparation method of the melamine resin / polyurethane composite polishing pad provided by the present invention first uses an organic modifier (isocyanate) to organically modify the porous melamine resin material, which has the following advantages: 1) the isocyanate can fully chemically bond with the amino groups on the inner and outer pore surfaces of the porous melamine resin by immersion modification, which is conducive to the uniform chemical adsorption of the isocyanate on the surface of the porous melamine resin; 2) the isocyanate adsorbed on the inner and outer surfaces of the porous melamine resin can further undergo a chemical grafting reaction with the polyurethane, so that the polyurethane resin is uniformly assembled and wrapped on the surface of the porous melamine resin. Then, a large number of micron-sized pores formed during the polyurethane flocculation (precipitation) reaction form a pore-pore interconnected structure with the micron-sized pores and nanopores (nanopores caused by the triazine ring molecular structure) existing in the melamine resin itself, thereby effectively increasing the pore density of the obtained porous melamine resin / polyurethane composite material.

[0034] (2) The preparation method provided by the present invention adopts freezing technology for treatment during the polyurethane flocculation (precipitation) process, which is beneficial to further improve the porosity and water permeability of the melamine resin / polyurethane composite material and further increase the pore density of the obtained material.

[0035] (3) The preparation method provided by the present invention fully utilizes the advantages of thermosetting resin (melamine resin) such as high hardness and good wear resistance, and uses porous melamine resin as a "hard skeleton" to compound with thermoplastic resin (polyurethane) to prepare melamine resin / polyurethane composite polishing pad material; the melamine resin / polyurethane composite polishing pad material prepared by the method of the present invention has both the rigid chain segment of melamine resin and the flexible chain segment of polyurethane resin, and by regulating the ratio of the two resins, a melamine resin / polyurethane composite polishing pad with moderate hardness is prepared, which effectively improves the comprehensive application performance of the polyurethane polishing pad such as hardness and wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 This is a high-definition microscope photograph of the melamine resin / polyurethane composite polishing pad prepared in Example 4 of the present invention;

[0038] Figure 2 This is a high-definition microscope photo of the melamine resin / polyurethane composite polishing pad prepared in Comparative Example 1;

[0039] Figure 3 This is a high-definition microscope photo of the melamine resin / polyurethane composite polishing pad prepared in Comparative Example 2;

[0040] Figure 4 This is a high-definition microscope photo of the melamine resin / polyurethane composite polishing pad prepared in Comparative Example 3. DETAILED DESCRIPTION

[0041] The following will be combined with the accompanying 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 embodiments described are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Example 1

[0043] Provided is a method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that the method comprises the following steps:

[0044] 1. Preparation of modified porous melamine resin:

[0045] S1. Add 0.05 kg of toluene diisocyanate (organic modifier) ​​to 1.0 kg of acetone (first solvent) and stir evenly to obtain a modified solution;

[0046] S2. Immersing 2.5 kg of porous melamine resin in the modified solution and subjecting it to an adsorption reaction at 60° C., while simultaneously condensing and recovering acetone until the acetone is completely evaporated, removing the product after the reaction and drying it to obtain a modified porous melamine resin (i.e., toluene diisocyanate-modified porous melamine resin); wherein the porous melamine resin was purchased from Zhengzhou Fengtai Nanomaterial Co., Ltd.;

[0047] 2. Preparation of melamine resin / polyurethane composite polishing pad:

[0048] S1. Add polyurethane with a molecular weight of 30,000 to N,N-dimethylformamide (the second solvent) and stir evenly to prepare a polyurethane solution with a concentration of 5.0 wt %; wherein: the polyurethane is purchased from Shanghai Huide Technology Co., Ltd.;

[0049] S2, immersing the modified porous melamine resin in 100.0 kg of the polyurethane solution for adsorption reaction for 1 hour to obtain a porous melamine resin / polyurethane composite;

[0050] S3. Quickly remove the porous melamine resin / polyurethane composite product and re-immerse it in an aqueous solution with a volume concentration of 10% DMF (second solvent) for flocculation (precipitation) reaction, and freeze it at a temperature of -10°C for 6 hours. After returning to room temperature, the product is washed with deionized water, dried, ground, and cut to obtain a melamine resin / polyurethane composite polishing pad.

[0051] Example 2

[0052] Provided is a method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that the method comprises the following steps:

[0053] 1. Preparation of modified porous melamine resin:

[0054] S1. Add 0.2 kg of diphenylmethane diisocyanate to 1.0 kg of acetone and stir evenly to obtain a modified solution;

[0055] S2, immersing 4.0 kg of porous melamine resin in the above-mentioned modification solution, and performing an adsorption reaction at 80° C., while performing the adsorption reaction, condensing and recovering acetone until the acetone is completely evaporated, taking out the product after the reaction and drying it, thereby obtaining a modified porous melamine resin (diphenylmethane diisocyanate modified porous melamine resin);

[0056] Wherein: the porous melamine resin is purchased from Zhengzhou Fengtai Nanomaterial Co., Ltd.;

[0057] 2. Preparation of melamine resin / polyurethane composite polishing pad:

[0058] S1. Adding polyurethane with a molecular weight of 50,000 to N,N-dimethylformamide and stirring uniformly to prepare a polyurethane solution with a concentration of 20.0 wt%; wherein the polyurethane was purchased from Asahikawa Chemical (Kunshan) Co., Ltd.;

[0059] S2, immersing the modified porous melamine resin in 200.0 kg of the polyurethane solution for adsorption reaction for 3 hours to obtain a modified melamine resin / polyurethane composite;

[0060] S3. Quickly remove the product porous melamine resin / polyurethane composite and re-immerse it in an aqueous solution with a volume concentration of 25% DMF for flocculation (precipitation) reaction, and freeze it at a temperature of -20°C for 3 hours. After returning to room temperature, wash the product with deionized water, dry, grind, and cut to obtain a melamine resin / polyurethane composite polishing pad.

[0061] Example 3

[0062] Provided is a method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that the method comprises the following steps:

[0063] 1. Preparation of modified porous melamine resin:

[0064] S1. Add 0.1 kg of triphenylmethane triisocyanate to 1.0 kg of acetone and stir evenly to obtain a modified solution;

[0065] S2, immersing 2.8 kg of porous melamine resin in the above-mentioned modification solution, and performing an adsorption reaction at 70° C., while performing the adsorption reaction, condensing and recovering acetone until the acetone is completely evaporated, taking out the product after the reaction and drying it, thereby obtaining a modified porous melamine resin (triphenylmethane triisocyanate modified porous melamine resin);

[0066] Wherein: the porous melamine resin is purchased from Zhengzhou Fengtai Nanomaterial Co., Ltd.;

[0067] 2. Preparation of melamine resin / polyurethane composite polishing pad:

[0068] S1. Adding polyurethane with a molecular weight of 40,000 to N,N-dimethylformamide and stirring uniformly to prepare a polyurethane solution with a concentration of 10.0 wt%; wherein the polyurethane was purchased from Asahikawa Chemical (Kunshan) Co., Ltd.;

[0069] S2, immersing the modified porous melamine resin in 93.3 kg of the polyurethane solution for adsorption reaction for 2 hours to obtain a porous melamine resin / polyurethane composite;

[0070] S3. Quickly remove the product porous melamine resin / polyurethane composite and re-immerse it in an aqueous solution with a volume concentration of 20% DMF for flocculation (precipitation) reaction, and freeze it at a temperature of -15°C for 4 hours. After returning to room temperature, wash the product with deionized water, dry, grind, and cut to obtain a melamine resin / polyurethane composite polishing pad.

[0071] Example 4

[0072] Provided is a method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that the method comprises the following steps:

[0073] 1. Preparation of modified porous melamine resin:

[0074] S1. Add 0.15 kg of isophorone diisocyanate to 1.0 kg of acetone and stir evenly to obtain a modified solution;

[0075] S2, immersing 3.5 kg of porous melamine resin in the above-mentioned modification solution, and performing an adsorption reaction at 65° C., while performing the adsorption reaction, condensing and recovering acetone until the acetone is completely evaporated, taking out the product after the reaction and drying it, thereby obtaining a modified porous melamine resin (isophorone diisocyanate modified porous melamine resin);

[0076] Wherein: the porous melamine resin is purchased from Zhengzhou Fengtai Nanomaterial Co., Ltd.;

[0077] 2. Preparation of melamine resin / polyurethane composite polishing pad:

[0078] S1. Add polyurethane with a molecular weight of 45,000 to N,N-dimethylformamide and stir evenly to prepare a polyurethane solution with a concentration of 15.0 wt %; wherein: the polyurethane is purchased from Shanghai Huide Technology Co., Ltd.;

[0079] S2, immersing the modified porous melamine resin in 116.7 kg of polyurethane solution for adsorption reaction for 2.5 hours to obtain a porous melamine resin / polyurethane composite;

[0080] S3. Quickly remove the product porous melamine resin / polyurethane composite and re-immerse it in an aqueous solution with a volume concentration of 15% DMF for flocculation (precipitation) reaction, and freeze it at a temperature of -10°C for 5 hours. After returning to room temperature, wash the product with deionized water, dry, grind, and cut to obtain a melamine resin / polyurethane composite polishing pad.

[0081] Comparative Example 1

[0082] Provided is a method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that the method comprises the following steps:

[0083] (1) adding polyurethane with a molecular weight of 45,000 to N,N-dimethylformamide and stirring uniformly to prepare a polyurethane solution with a concentration of 15.0 wt%;

[0084] (2) immersing 3.5 kg of porous melamine resin in 116.7 kg of the above-mentioned polyurethane solution for adsorption reaction for 2.5 hours;

[0085] Wherein: the porous melamine resin is purchased from Zhengzhou Fengtai Nanomaterial Co., Ltd.;

[0086] (3) The product obtained in step (2) was quickly taken out and re-immersed in an aqueous solution with a volume concentration of 15% DMF for flocculation (precipitation) reaction, and at the same time, frozen at a temperature of -10°C for 5 hours. After returning to room temperature, the product was washed with deionized water, dried, ground, and cut to obtain a melamine resin / polyurethane composite polishing pad.

[0087] The difference between the above-mentioned Comparative Example 1 and Example 4 is that the porous melamine resin is not modified in Comparative Example 1, that is, Comparative Example 1 does not perform the modified porous melamine resin preparation steps in Examples 1 to 4 above, and the remaining preparation conditions of Comparative Example 1 are the same as those of Example 4.

[0088] Comparative Example 2

[0089] Provided is a method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that the method comprises the following steps:

[0090] 1. Preparation of modified porous melamine resin:

[0091] S1. Add 0.15 kg of isophorone diisocyanate to 1.0 kg of acetone and stir evenly to obtain a modified solution;

[0092] S2, immersing 3.5 kg of porous melamine resin in the above-mentioned modification solution, and performing an adsorption reaction at 65° C., while performing the adsorption reaction, condensing and recovering acetone until the acetone is completely evaporated, taking out the product after the reaction and drying it, thereby obtaining a modified porous melamine resin (isophorone diisocyanate modified porous melamine resin);

[0093] Wherein: the porous melamine resin is purchased from Zhengzhou Fengtai Nanomaterial Co., Ltd.;

[0094] 2. Preparation of melamine resin / polyurethane composite polishing pad:

[0095] S1. Add polyurethane with a molecular weight of 45,000 to N,N-dimethylformamide and stir evenly to prepare a polyurethane solution with a concentration of 15.0 wt%; wherein: the polyurethane is purchased from Shanghai Huide Technology Co., Ltd.;

[0096] S2, immersing the modified porous melamine resin in 116.7 kg of polyurethane solution for adsorption reaction for 2.5 hours to obtain a porous melamine resin / polyurethane composite;

[0097] S3. Quickly remove the porous melamine resin / polyurethane composite product and re-immerse it in an aqueous solution with a volume concentration of 15% DMF for flocculation (precipitation) reaction. After the reaction, wash the product with deionized water, dry, grind, and cut to obtain a melamine resin / polyurethane composite polishing pad.

[0098] The difference between Comparative Example 2 and Example 4 is that no freezing treatment process is performed during the preparation process of Comparative Example 2, and the other preparation conditions of Comparative Example 2 are the same as those of Example 4.

[0099] Comparative Example 3

[0100] Provided is a method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that the method comprises the following steps:

[0101] 1. Preparation of modified melamine resin:

[0102] S1. Add 0.15 kg of isophorone diisocyanate to 1.0 kg of acetone and stir evenly to obtain a modified solution;

[0103] S2, 3.5kg of unfoamed melamine resin material (specific surface area of ​​about 1.4843m 2 / g, pore volume of about 0.000426cm 3 / g) is immersed in the above-mentioned modification solution and subjected to adsorption reaction at 65°C, while condensing and recovering acetone until the acetone is completely evaporated, and the product is taken out and dried after the reaction to obtain a modified melamine resin;

[0104] 2. Preparation of melamine resin / polyurethane composite polishing pad:

[0105] S1. Add polyurethane with a molecular weight of 45,000 to N,N-dimethylformamide and stir evenly to prepare a polyurethane solution with a concentration of 15.0 wt%;

[0106] S2, immersing the modified melamine resin in 116.7 kg of polyurethane solution for adsorption reaction for 2.5 hours to obtain a melamine resin / polyurethane composite;

[0107] S3. Quickly remove the product melamine resin / polyurethane composite and re-immerse it in an aqueous solution with a volume concentration of 15% DMF for flocculation (precipitation) reaction, and freeze it at a temperature of -10°C for 5 hours. After returning to room temperature, the product is washed with deionized water, dried, ground, and cut to obtain a melamine resin / polyurethane composite polishing pad.

[0108] The difference between Comparative Example 3 and Example 4 is that the unfoamed melamine resin used in Comparative Example 3 is different from the porous melamine resin used in Example 4; the other preparation conditions of Comparative Example 3 are the same as those of Example 4.

[0109] Performance testing:

[0110] According to the preparation steps: a melamine resin / polyurethane composite polishing pad material is prepared after drying, grinding, and cutting. The composite polishing pad is then made into a 4cm*2cm rectangular sample for wear resistance and hardness testing:

[0111] (1) Wear resistance test: The wear resistance of the melamine resin / polyurethane composite polishing pads obtained in Examples 1 to 4 and Comparative Examples 1 to 3 was tested;

[0112] The test method was based on ASTM D 3884-2000. An abrasion tester (GT-7012-T, Shanghai Hongfu Instrument Co., Ltd.) was used. The H-22 grinding wheel (1.0 kg load) was used. The weight loss rate was measured after 1000 cycles of grinding. The test results are shown in Table 1.

[0113] (2) Hardness Performance Test: The hardness of the melamine resin / polyurethane composite polishing pads obtained in Examples 1 to 4 and Comparative Examples 1 to 3 was tested according to the national standard GB / T 2411-2008. The test results are shown in Table 1. The test steps are as follows:

[0114] ① Place the obtained sample horizontally and place a piece of the same sample below it. The sample should not be wrinkled or bent.

[0115] ② Place the hardness tester flat on the test sample, place your finger on the circular notch at the top of the hardness tester, and press down hard until the pointer of the hardness tester stops moving;

[0116] ③Record the pointer reading as the hardness of the sample at this test point; repeat the above operation, take six points to test its hardness, and finally take the average value (round up).

[0117] (3) Bulk density test: The melamine resin / polyurethane composite polishing pads obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were tested for bulk density using a bulk density instrument according to the national standard GB / T 9984.9. The test results are shown in Table 1.

[0118] Table 1 shows the wear resistance, hardness and bulk density test results of the melamine resin / polyurethane composite polishing pads obtained in Examples 1 to 4 and Comparative Examples 1 to 4.

[0119]

[0120] From the test results in Table 1, it can be seen that the melamine resin / polyurethane composite polishing pad prepared by the method of the present invention has a lower weight loss rate, indicating that it has better wear resistance; the melamine resin / polyurethane composite polishing pad prepared by the method of the present invention has better hardness; and at the same time, the bulk density is lower, indicating that the porosity of the material is higher.

[0121] Microscopic characterization:

[0122] The melamine resin / polyurethane composite polishing pads prepared in Example 4 and Comparative Examples 1 to 3 were observed using a FLY-MV2H800 high-definition microscope produced by Shanghai Fulai Optical Technology Co., Ltd. The results are as follows: Figures 1 to 4 As shown;

[0123] (1) By Figure 1 It can be seen that the surface of the melamine resin / polyurethane composite polishing pad prepared in Example 4 of the present invention has a rich pore structure with relatively uniform pore size, indicating that the preparation method of the present invention effectively improves the porosity of the obtained product;

[0124] (2) By Figure 2It can be seen that the melamine resin / polyurethane composite polishing pad prepared in Comparative Example 1 has fewer pore structures on its surface (compared to Figure 1 Obviously less); the side proves that the present invention greatly improves the porosity of the obtained product by modifying the porous melamine resin with isocyanate;

[0125] (3) By Figure 3 It can be seen that the pore structure on the surface of the melamine resin / polyurethane composite polishing pad prepared in Comparative Example 2 is significantly less than that in Example 4 ( Figure 1 It is shown); it is proved that the preparation method of the present invention is conducive to improving the porosity of the obtained melamine resin / polyurethane composite polishing pad material by adopting a freezing process, and further increases the pore density of the obtained material;

[0126] (4) By Figure 4 It can be seen that the pore structure on the surface of the melamine resin / polyurethane composite polishing pad prepared in Comparative Example 3 is also significantly less than that in Example 4 ( Figure 1 As shown); it is proved that in the preparation method of the present invention, by using porous melamine resin as a skeleton, compared with the comparative example 3 using unfoamed melamine resin, the porous melamine resin used in the present invention is more conducive to the adsorption of the modifier (isocyanate), thereby being more conducive to the chemical bonding of isocyanate and porous melamine resin, and being conducive to the chemical grafting reaction between isocyanate and polyurethane, so that the polyurethane resin is uniformly assembled and wrapped on the surface of the melamine resin, and then a large number of micropores formed in the polyurethane flocculation and foaming process form a pore-pore interconnected structure with the micropores and nanopores in the porous melamine resin itself, thereby effectively increasing the pore density of the melamine resin / polyurethane composite polishing pad material and making the porosity higher.

[0127] From the above performance test and microscopic characterization results, it can be seen that the composite polishing pad prepared by the method of the present invention has multiple characteristics such as high hardness, good wear resistance and high porosity.

[0128] The above preferred embodiments of the present invention are only used to explain the present invention and are not used to limit the present invention. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a melamine resin / polyurethane composite polishing pad, characterized in that: The method comprises the following steps:

1. Preparation of modified porous melamine resin: S1, adding an organic modifier to a first solvent and stirring uniformly to obtain a modified solution; the organic modifier is an isocyanate; S2, immersing the porous melamine resin in the modification solution to react, taking out the product after the reaction and drying it to obtain a modified porous melamine resin; 2. Preparation of melamine resin / polyurethane composite polishing pad: S1, adding polyurethane to the second solvent and stirring evenly to obtain a polyurethane solution; S2, impregnating the modified porous melamine resin in the polyurethane solution to react, thereby preparing a porous melamine resin / polyurethane composite; S3. Immersing the porous melamine resin / polyurethane composite in an aqueous solution of the second solvent for flocculation reaction, while freezing the composite. After returning to room temperature, the composite is washed, dried, ground, and cut to obtain a melamine resin / polyurethane composite polishing pad.

2. The method for preparing a melamine resin / polyurethane composite polishing pad according to claim 1, wherein:

1. Preparation of modified porous melamine resin: In step S1, the first solvent is acetone; the mass ratio of the organic modifier to the first solvent is (0.05-0.2):

1.

3. The method for preparing a melamine resin / polyurethane composite polishing pad according to claim 1, characterized in that: The isocyanate is selected from any one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, and meta-xylylenediisocyanate.

4. The method for preparing a melamine resin / polyurethane composite polishing pad according to claim 1, wherein:

1. Preparation of modified porous melamine resin: Step S2, immersing the porous melamine resin in the modified solution and reacting at 60-80° C., while condensing and recovering the first solvent until the first solvent is completely evaporated, taking out the product after the reaction and drying it to obtain a modified porous melamine resin; Wherein, the mass ratio of the porous melamine resin to the organic modifier is 1: (0.02～0.05)。 5. The method for preparing a melamine resin / polyurethane composite polishing pad according to claim 1, wherein:

2. Preparation of melamine resin / polyurethane composite polishing pad: In step S1, the second solvent is N,N-dimethylformamide; The mass fraction of polyurethane in the polyurethane solution in step S1 is 5.0% to 20.0%.

6. The method for preparing a melamine resin / polyurethane composite polishing pad according to claim 1 or 5, characterized in that:

2. Preparation of melamine resin / polyurethane composite polishing pad: The molecular weight of the polyurethane in step S1 is 30,000 to 50,000.

7. The method for preparing a melamine resin / polyurethane composite polishing pad according to claim 1, characterized in that:

2. Preparation of melamine resin / polyurethane composite polishing pad: The mass ratio of the modified porous melamine resin to the polyurethane in step S2 is (0.1-0.5):1; The reaction time in step S2 is 1 to 3 hours.

8. The method for preparing a melamine resin / polyurethane composite polishing pad according to claim 1, characterized in that:

2. Preparation of melamine resin / polyurethane composite polishing pad: The volume concentration of the aqueous solution of the second solvent in step S3 is 10.0% to 25.0%; The freezing temperature in step S3 is -20°C to -10°C, and the freezing time is 3 to 6 hours.

9. A melamine resin / polyurethane composite polishing pad, characterized in that: The melamine resin / polyurethane composite polishing pad is prepared by the preparation method according to any one of claims 1 to 8.

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