A waterborne polyurethane composite porous polishing pad and preparation method thereof

Abstract

The application discloses a kind of water-based polyurethane composite porous polishing pad and preparation method thereof, belong to polishing pad technical field.A kind of water-based polyurethane composite porous polishing pad, including substrate layer, adhesive layer and polishing layer, the surface of substrate layer is adhered with polishing layer by adhesive layer, and adhesive layer is prepared using sulfonate type water-based polyurethane;Polishing layer includes the following weight parts raw materials: modified water-based polyurethane 56 parts, curing agent 7 parts and nano abrasive 4 parts.The application solves the problem of insufficient flexibility of existing polishing pad, the water-based polyurethane composite porous polishing pad and preparation method thereof proposed by the application, substrate layer and polishing layer are bonded by adhesive layer, palm fiber is added in substrate layer, the elasticity of substrate layer as a whole is improved, and modified palm fiber is mixed in modified water-based polyurethane in polishing layer, and the structure of adhered substrate layer and polishing layer is firm, soft and hard, and the polishing effect is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polishing pads, in particular to a water-based polyurethane composite porous polishing pad and a preparation method thereof. BACKGROUND

[0002] The polishing pad is used as a carrier for storing and transporting polishing liquid and provides certain physical bearing capacity during polishing. A Chinese patent with publication number CN112300355B discloses a two-component water-based polyurethane, its use, a polyurethane composite polishing pad formed therefrom and a preparation method. The two-component water-based polyurethane of the invention comprises a water-based polyurethane resin and a water-based polyurethane curing agent. The invention significantly improves the hardness, strength and wear resistance of the composite polishing pad after the adhesion of the fiber filaments by mixing the water-based polyurethane curing agent with the water-based polyurethane resin and then treating the base material with a specific process.

[0003] However, the polishing pad prepared by fully impregnating the base material in the patent has high integrity and good rigidity, but lacks flexibility. SUMMARY

[0004] The present application relates to the technical field of polishing pads, in particular to a water-based polyurethane composite porous polishing pad and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a water-based polyurethane composite porous polishing pad, comprising a base layer, an adhesive layer and a polishing layer, the surface of the base layer is bonded with the polishing layer through the adhesive layer, the adhesive layer is prepared from a sulfonate type water-based polyurethane, and the polishing layer comprises the following raw materials by weight: modified water-based polyurethane 56-75 parts, curing agent 3-20 parts and nano abrasive 2-9 parts.

[0006] Preferably, the preparation method of the modified water-based polyurethane is as follows: IPDI and polyethylene glycol are heated and reacted at 90-100 DEG C, and after cooling to below 30 DEG C, a mixture of dimethylol propionic acid and 1, 4-butanediol is added and heated and reacted at 45-60 DEG C to obtain a prepolymer.

[0007] The surface-modified palm fiber is soaked in deionized water, and after soaking for more than 4 hours, solid-liquid separation is performed, the soaked palm fiber is impregnated in the sulfonate type water-based polyurethane, so that the sulfonate type water-based polyurethane is adhered to the surface of the palm fiber, and the excess sulfonate type water-based polyurethane is filtered, leaving the modified palm fiber.

[0008] The modified palm fiber and polyether amine are added into the prepolymer, and heated to react at 50-60℃, then hydroxyethyl methacrylate is added for end-capping, a polymerization inhibitor is added, and stirred to react at 25-35℃, finally a dispersing agent is added, stirred, and then the modified waterborne polyurethane is obtained.

[0009] Preferably, the mass ratio of the modified palm fiber, polyether amine and prepolymer is 12-25:1-2:220-250; the polyether amine is a polyether containing double-end amino groups, and the molecular weight is 500-1000.

[0010] Preferably, the surface modification method of the palm fiber is as follows: the palm fiber raw material is dried at 80℃, the dried palm fiber is soaked in an alkali solution for 24h, the alkali solution is 20% sodium hydroxide, then the palm fiber is washed and soaked in deionized water until neutral, filtered and dried, to obtain the alkali-treated palm fiber, the alkali-treated palm fiber is added into a 5% hexadecyltrimethoxysilane anhydrous methanol solution, the solution is adjusted to pH 5 with acetic acid, and stirred to react at room temperature for 24h, then the fiber after reaction is washed and soaked in deionized water to remove unreacted hexadecyltrimethoxysilane, and the palm fiber is dried at 90℃, ground and crushed to obtain the surface-modified palm fiber.

[0011] Preferably, the preparation method of the sulfonate type waterborne polyurethane is as follows: polybrominated diphenyl ether, HDI, IPDI and dibutyltin dilaurate are stirred, a measured amount of 1,4-butanediol and epoxy resin are added, and the reaction is kept until the NCO content reaches the specified value, then ethanol is added to reduce viscosity, sulfonate chain extender AAS is added for reaction, and ethylenediamine is added for chain extension, and the acetone is removed by vacuum evaporation, to obtain the epoxy-modified sulfonate type waterborne polyurethane.

[0012] Preferably, the epoxy resin is added in a mass fraction of 4%, the w(non-volatile matter) of the sulfonate type waterborne polyurethane is greater than 50%, the viscosity is greater than 95mPa·s, and the tensile strength is greater than 15MPa.

[0013] Preferably, the base layer is cured from the waterborne polyurethane, and the waterborne polyurethane comprises the following raw materials in parts by weight: waterborne polyurethane resin 50-78 parts, curing agent 2-18 parts and palm fiber 2-9 parts.

[0014] Preferably, the curing agent comprises the following raw materials in parts by weight: diphenylmethane diisocyanate 28 parts, polyethylene glycol 62 parts, tris(2-hydroxyethyl)methylammonium hydroxide 1 part and nonylphenol 2 parts.

[0015] Preferably, the nano abrasive comprises the following raw materials in parts by weight: nano cerium 2-5 parts, nano alumina 3-4 parts and nano silicon oxide 1-2 parts.

[0016] Another technical problem to be solved by the present application is to provide a preparation method of the water-based polyurethane composite porous polishing pad, comprising the following steps:

[0017] S1: after the water-based polyurethane resin and the palm fiber are uniformly mixed and stirred, the curing agent is added, and after mixing, the water-based polyurethane is prepared, the water-based polyurethane is coated on the substrate, and after heat curing, the base layer is prepared;

[0018] S2: after the modified water-based polyurethane and the nano abrasive are mixed according to the amount, the curing agent is added and uniformly stirred, and then coated on the substrate, and after heat curing, the polishing layer is prepared;

[0019] S3: the prepared sulfonate type water-based polyurethane is coated between the base layer and the polishing layer, and is heat cured, and after cutting and polishing, the water-based polyurethane composite porous polishing pad is prepared.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] The base layer and the polishing layer are bonded by the adhesive layer, the palm fiber is added in the base layer, the elasticity of the base layer as a whole is improved, the modified palm fiber is mixed in the modified water-based polyurethane in the polishing layer, the palm fiber absorbs water and expands, the internal void space increases, and the sulfonate type water-based polyurethane is adhered, the modified palm fiber with the sulfonate type water-based polyurethane can be firmly bonded with the water-based polyurethane, the modified palm fiber forms a reticular structure in the water-based polyurethane, the palm fiber soaked in the sulfonate type water-based polyurethane can prevent shrinkage, improve the hardness of the polishing layer, and the water absorbed in the palm fiber is evaporated during the processing of the polishing layer, the micropores of the polishing layer are increased, the adhesive layer is prepared by using the sulfonate type water-based polyurethane, the adhesion is good, the structure of the bonded base layer and polishing layer is firm, and the polishing effect is good. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure is a structure diagram of the water-based polyurethane composite porous polishing pad of the present application.

[0023] In the figure: 1, base layer; 2, adhesive layer; 3, polishing layer. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] Embodiment one:

[0026] In order to solve the problem of the polishing pad made by fully impregnating the base material, which has high integrity, good rigidity, but poor flexibility, please refer to Figure 1 The embodiment provides the following technical scheme:

[0027] A water-based polyurethane composite porous polishing pad comprises a base layer 1, an adhesive layer 2 and a polishing layer 3, the surface of the base layer 1 is bonded with the polishing layer 3 through the adhesive layer 2, and the adhesive layer 2 is prepared from a sulfonate type water-based polyurethane.

[0028] The polishing layer 3 comprises the following raw materials in parts by weight: 56 parts of modified water-based polyurethane, 7 parts of a curing agent and 4 parts of nano abrasive;

[0029] The preparation method of the modified water-based polyurethane is as follows: IPDI and polyethylene glycol are heated to react at 90 DEG C, and after cooling to below 30 DEG C, a mixture of dimethylol propionic acid and 1,4-butanediol is added and heated to react at 45 DEG C to obtain a prepolymer;

[0030] The palm fiber with the modified surface is soaked in deionized water, after soaking for more than 4 hours, the palm fiber swells after soaking, the internal void space increases, and the soaked palm fiber is impregnated in the sulfonate type water-based polyurethane, so that the sulfonate type water-based polyurethane is adhered to the surface of the palm fiber, and the excess sulfonate type water-based polyurethane is filtered, leaving the modified palm fiber;

[0031] The modified palm fiber and the polyether amine are added to the prepolymer and heated to react at 50 DEG C, then hydroxyethyl methacrylate is added for end-capping, a polymerization inhibitor is added, and stirring is carried out at 25 DEG C, and finally a dispersing agent is added and stirred to obtain the modified water-based polyurethane, the modified palm fiber with the sulfonate type water-based polyurethane can be firmly bonded with the water-based polyurethane, the modified palm fiber forms a reticular structure in the water-based polyurethane, the toughness of the entire polishing layer 3 is improved, and the wear during polishing is reduced.

[0032] The mass ratio of the modified palm fiber, the polyether amine and the prepolymer is 12:1:220; the polyether amine is a polyether containing double-end amino groups, and the molecular weight is 500-1000.

[0033] The surface modification method of palm fiber is as follows: the palm fiber raw material is dried at 80℃, the dried palm fiber is soaked in 20% sodium hydroxide solution for 24h, then washed and soaked with deionized water until neutral, filtered and dried, to prepare alkali treated palm fiber, then the alkali treated palm fiber is added into 5% hexadecyl trimethoxysilane anhydrous methanol solution, the solution is adjusted to pH 5 with acetic acid, stirred at room temperature for 24h, then the fiber is separated from the solution, washed and soaked with deionized water to remove unreacted hexadecyl trimethoxysilane, and the palm fiber is dried at 90℃, ground and crushed to obtain surface modified palm fiber.

[0034] The preparation method of sulfonate type waterborne polyurethane is as follows: polybrominated diphenyl ether is stirred with HDI, IPDI and dibutyltin dilaurate, and a certain amount of 1,4-butanediol and epoxy resin is added, and the reaction is carried out under heat until the NCO content reaches the specified value, then ethanol is added to reduce viscosity, sulfonate chain extender AAS is added for reaction, and then ethylenediamine is added for chain extension, and acetone is removed by vacuum evaporation to obtain epoxy modified sulfonate type waterborne polyurethane, the mass fraction of epoxy resin is 4%, and after the introduction of epoxy resin, the crosslinking density is improved due to the introduction of rigid benzene ring structure, which can improve the thermal decomposition temperature of the film, that is, the thermal stability of the film is significantly improved, the w(non-volatile matter) of the sulfonate type waterborne polyurethane is greater than 50%, the viscosity is greater than 95mPa·s, and the tensile strength is greater than 15MPa.

[0035] The base layer 1 is cured from waterborne polyurethane, and the waterborne polyurethane comprises the following raw materials by weight: waterborne polyurethane resin 55 parts, curing agent 8 parts and palm fiber 5 parts.

[0036] The curing agent comprises the following raw materials by weight: diphenylmethane diisocyanate 28 parts, polyethylene glycol 62 parts, tris(2-hydroxyethyl)methylammonium hydroxide 1 part and nonylphenol 2 parts.

[0037] The nano abrasive comprises the following raw materials by weight: nano cerium 3 parts, nano aluminum oxide 3 parts and nano silicon oxide 2 parts.

[0038] In order to better show the preparation process of the waterborne polyurethane composite porous polishing pad, the present embodiment proposes a preparation method of waterborne polyurethane composite porous polishing pad, which comprises the following steps:

[0039] Step one: mix and stir the waterborne polyurethane resin and palm fiber uniformly, then add the curing agent, mix and prepare the waterborne polyurethane, coat the waterborne polyurethane on the substrate, and after heat curing, the base layer 1 is prepared;

[0040] Step two: mix the modified waterborne polyurethane and nano abrasive according to the amount, then add the curing agent and stir uniformly, coat on the substrate, and after heat curing, the polishing layer 3 is prepared;

[0041] Step three: the prepared sulfonate type waterborne polyurethane is coated between the base layer 1 and the polishing layer 3, and heated and cured, and after cutting and polishing, a waterborne polyurethane composite porous polishing pad is prepared.

[0042] Example two:

[0043] A waterborne polyurethane composite porous polishing pad, comprising a base layer 1, an adhesive layer 2 and a polishing layer 3, the surface of the base layer 1 is bonded with the polishing layer 3 through the adhesive layer 2, and the adhesive layer 2 is prepared by using a sulfonate type waterborne polyurethane.

[0044] The polishing layer 3 comprises the following raw materials by weight: modified waterborne polyurethane 56 parts, curing agent 7 parts and nano abrasive 4 parts.

[0045] The preparation method of the modified waterborne polyurethane is as in example one, wherein the mass ratio of the modified palm fiber, polyether amine and prepolymer is 15:1:220; the polyether amine is a polyether containing double-end amino groups, and the molecular weight is 500-1000.

[0046] The base layer 1 is cured by waterborne polyurethane, and the waterborne polyurethane comprises the following raw materials by weight: waterborne polyurethane resin 55 parts, curing agent 8 parts and palm fiber 5 parts.

[0047] The curing agent comprises the following raw materials by weight: diphenyl methane diisocyanate 28 parts, polyethylene glycol 62 parts, tris (2-hydroxyethyl) methyl ammonium hydroxide 1 part and nonyl phenol 2 parts.

[0048] The nano abrasive comprises the following raw materials by weight: nano cerium 3 parts, nano alumina 3 parts and nano silicon oxide 2 parts.

[0049] The polishing pad is prepared by the method of example one.

[0050] Example three:

[0051] A waterborne polyurethane composite porous polishing pad, comprising a base layer 1, an adhesive layer 2 and a polishing layer 3, the surface of the base layer 1 is bonded with the polishing layer 3 through the adhesive layer 2, and the adhesive layer 2 is prepared by using a sulfonate type waterborne polyurethane.

[0052] The polishing layer 3 comprises the following raw materials by weight: modified waterborne polyurethane 70 parts, curing agent 15 parts and nano abrasive 4 parts.

[0053] The preparation method of the modified waterborne polyurethane is as in example one, wherein the mass ratio of the modified palm fiber, polyether amine and prepolymer is 12:1:220; the polyether amine is a polyether containing double-end amino groups, and the molecular weight is 500-1000.

[0054] The base layer 1 is cured from a water-based polyurethane including the following raw materials in parts by weight: a water-based polyurethane resin 55 parts, a curing agent 8 parts, and palm fibers 5 parts.

[0055] The curing agent includes the following raw materials in parts by weight: diphenyl methane diisocyanate 28 parts, polyethylene glycol 62 parts, tri(2-hydroxyethyl)methyl ammonium hydroxide 1 part, and nonyl phenol 2 parts.

[0056] The nano abrasive includes the following raw materials in parts by weight: nano cerium 3 parts, nano alumina 3 parts, and nano silica 2 parts.

[0057] A polishing pad is prepared using the method of Example 1.

[0058] Comparative Example 1

[0059] A water-based polyurethane composite porous polishing pad includes a base layer 1, an adhesive layer 2, and a polishing layer 3, the surface of the base layer 1 is adhered with the polishing layer 3 through the adhesive layer 2, and the adhesive layer 2 is prepared from a sulfonate type water-based polyurethane.

[0060] The polishing layer 3 includes the following raw materials in parts by weight: a water-based polyurethane resin 56 parts, a curing agent 7 parts, and a nano abrasive 4 parts.

[0061] The base layer 1 is cured from a water-based polyurethane including the following raw materials in parts by weight: a water-based polyurethane resin 55 parts, a curing agent 8 parts, and palm fibers 5 parts.

[0062] The curing agent includes the following raw materials in parts by weight: diphenyl methane diisocyanate 28 parts, polyethylene glycol 62 parts, tri(2-hydroxyethyl)methyl ammonium hydroxide 1 part, and nonyl phenol 2 parts.

[0063] The nano abrasive includes the following raw materials in parts by weight: nano cerium 3 parts, nano alumina 3 parts, and nano silica 2 parts.

[0064] In this comparative example, a water-based polyurethane resin is used instead of a modified water-based polyurethane to prepare a polishing pad using the method of Example 1.

[0065] Comparative Example 2

[0066] A water-based polyurethane composite porous polishing pad includes a base layer 1 and a polishing layer 3, and the surface of the base layer 1 is provided with the polishing layer 3.

[0067] The polishing layer 3 includes the following raw materials in parts by weight: a modified water-based polyurethane 56 parts, a curing agent 7 parts, and a nano abrasive 4 parts.

[0068] The base layer 1 is cured from a water-based polyurethane including the following raw materials in parts by weight: a water-based polyurethane resin 55 parts and a curing agent 8 parts.

[0069] The curing agent comprises the following raw materials in parts by weight: 28 parts of diphenylmethane diisocyanate, 62 parts of polyethylene glycol, 1 part of tris(2-hydroxyethyl)methylammonium hydroxide and 2 parts of nonylphenol.

[0070] The nano-abrasive comprises the following raw materials in parts by weight: 3 parts of nano-cerium, 3 parts of nano-aluminum oxide and 2 parts of nano-silicon oxide.

[0071] The polishing pad is prepared as follows:

[0072] Step 1: Adding a waterborne polyurethane resin to a curing agent, mixing and forming a waterborne polyurethane, coating the waterborne polyurethane on a substrate, and heat curing to form a base layer 1;

[0073] Step 2: Modified waterborne polyurethane and nano-abrasive are measured and mixed, and then a curing agent is added and stirred evenly, and then coated on the base layer 1. After heat curing, it is cut and polished to make a waterborne polyurethane composite porous polishing pad.

[0074] In this comparative example, no adhesive layer was provided.

[0075] The polishing pads prepared in the above examples and comparative examples were tested to obtain the following data:

[0076]

[0077]

[0078] It can be concluded from the above table that the polishing pads prepared in Examples 1 to 3 and Comparative Example 2 have a higher hardness due to the use of modified water-based polyurethane in the polishing layer 3. At the same time, the base layer 1 of the polishing pads prepared in Examples 1 to 3 and Comparative Example 1 has a higher compression ratio. The base layer 1 has higher elasticity due to the use of palm fiber. Comparative Example 2 does not use palm fiber and has insufficient elasticity. In addition, the grinding losses of Comparative Examples 1 and 2 are higher than those of the examples, indicating that the polishing pads prepared using ordinary water-based polyurethane are not as wear-resistant as the polishing pads prepared using modified water-based polyurethane, and the absence of the adhesive layer 2 will also affect the wear effect. In addition, Examples 1 to 3 have smaller pore sizes and higher surface porosities than Comparative Example 1, indicating that the modified water-based polyurethane used in Examples 1 to 3 is beneficial to improving the uniformity of the micropores.

[0079] In summary: The present invention proposes a water-based polyurethane composite porous polishing pad and a preparation method thereof, wherein a base layer 1 and a polishing layer 3 are bonded by an adhesive layer 2, palm fibers are added to the base layer 1 to improve the overall elasticity of the base layer 1, and modified palm fibers are mixed with modified water-based polyurethane in the polishing layer 3. The palm fibers absorb enough water to swell, the internal void space increases, and the sulfonate-type water-based polyurethane is adhered to the modified palm fibers. The modified palm fibers with the sulfonate-type water-based polyurethane can be firmly bonded to the water-based polyurethane, and the modified palm fibers form a network structure in the water-based polyurethane. The palm fibers soaked in the sulfonate-type water-based polyurethane can prevent shrinkage and improve the hardness of the polishing layer 3. When processing the polishing layer 3, the water absorbed in the palm fibers is evaporated, and the micropores of the polishing layer 3 are increased. The adhesive layer 2 is prepared using the sulfonate-type water-based polyurethane, has good viscosity, and the adhered base layer 1 and polishing layer 3 have a firm structure, are both soft and hard, and have a good polishing effect.

[0080] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0081] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A waterborne polyurethane composite porous polishing pad comprising a base layer (1), an adhesive layer (2) and a polishing layer (3), characterized in that: The surface of the base layer (1) is bonded with a polishing layer (3) via an adhesive layer (2), wherein the adhesive layer (2) is prepared from sulfonate-type waterborne polyurethane, and the polishing layer (3) comprises the following raw materials in parts by weight: 56-75 parts of modified waterborne polyurethane, 3-20 parts of curing agent, and 2-9 parts of nano-abrasive; The preparation method of the modified waterborne polyurethane is as follows: IPDI and polyethylene glycol are heated at 90-100° C. for reaction, the temperature is lowered to below 30° C., a mixture of dimethylolpropionic acid and 1,4-butanediol is added, and the mixture is heated at 45-60° C. for reaction to obtain a prepolymer; The surface-modified palm fiber is soaked in deionized water for more than 4 hours, and then the solid and liquid are separated. The soaked palm fiber is then immersed in sulfonate-based waterborne polyurethane, so that the surface of the palm fiber is adhered to the sulfonate-based waterborne polyurethane. The excess sulfonate-based waterborne polyurethane is filtered out, leaving the modified palm fiber. The modified palm fiber and polyetheramine are added to the prepolymer and heated at 50-60°C for reaction, followed by addition of hydroxyethyl methacrylate for end-capping, addition of a polymerization inhibitor, stirring and reacting at 25-35°C, and finally addition of a dispersant and stirring to obtain a modified waterborne polyurethane; The preparation method of the sulfonate-type waterborne polyurethane is as follows: polybrominated diphenyl ether is mixed with HDI, IPDI and dibutyltin dilaurate, 1,4-butanediol and epoxy resin are added in measured amounts, and the mixture is kept warm for reaction until the NCO content reaches a specified value, ethanol is added to reduce viscosity, and a sulfonate chain extender AAS is added for reaction, and ethylenediamine is added for chain extension, and acetone is evaporated under reduced pressure to obtain epoxy-modified sulfonate-type waterborne polyurethane.

2. The waterborne polyurethane composite porous polishing pad according to claim 1, characterized in that: The mass ratio of the modified palm fiber, polyetheramine and prepolymer is 12-25:1-2:220-250; the polyetheramine is a polyether containing double-terminal amino groups and has a molecular weight of 500-1000.

3. The waterborne polyurethane composite porous polishing pad according to claim 2, characterized in that: The surface modification method of the palm fiber is as follows: drying the palm fiber raw material at 80° C., soaking the dried palm fiber in an alkali solution for 24 hours, wherein the alkali solution is 20% by mass of sodium hydroxide, then washing and soaking the palm fiber with deionized water until neutral, filtering and drying to prepare alkali-treated palm fiber, adding the alkali-treated palm fiber to an anhydrous methanol solution with a mass fraction of 5% hexadecyltrimethoxysilane, adjusting the pH value of the solution to 5 with acetic acid, stirring and reacting at room temperature for 24 hours, after solid-liquid separation, washing and soaking the reacted fiber with deionized water to remove unreacted hexadecyltrimethoxysilane, then drying the palm fiber at 90° C., grinding and crushing to obtain palm fiber with good surface modification.

4. The waterborne polyurethane composite porous polishing pad according to claim 3, characterized in that: The epoxy resin is added in an amount of 4% by mass, the w of the sulfonate-type waterborne polyurethane is greater than 50%, the viscosity is greater than 95 mPa·s, and the tensile strength is greater than 15 MPa.

5. The waterborne polyurethane composite porous polishing pad according to claim 4, characterized in that: The base layer (1) is formed by curing waterborne polyurethane, which comprises the following raw materials in parts by weight: 50-78 parts of waterborne polyurethane resin, 2-18 parts of curing agent and 2-9 parts of palm fiber.

6. The waterborne polyurethane composite porous polishing pad according to claim 5, characterized in that: The curing agent comprises the following raw materials in parts by weight: 28 parts of diphenylmethane diisocyanate, 62 parts of polyethylene glycol, 1 part of tris(2-hydroxyethyl)methylammonium hydroxide and 2 parts of nonylphenol.

7. The waterborne polyurethane composite porous polishing pad according to claim 6, characterized in that: The nano-abrasive comprises the following raw materials in parts by weight: 2-5 parts of nano-cerium, 3-4 parts of nano-aluminum oxide and 1-2 parts of nano-silicon oxide.

8. A method for preparing the waterborne polyurethane composite porous polishing pad according to claim 7, characterized in that: The following steps are involved: S1: After mixing and stirring the waterborne polyurethane resin and palm fiber, a curing agent is added and mixed to form a waterborne polyurethane, which is then coated on a substrate and thermally cured to form a base layer (1); S2: Modified waterborne polyurethane and nano-abrasive are measured and mixed, and then a curing agent is added and stirred evenly, and then coated on the substrate and thermally cured to form a polishing layer (3); S3: The prepared sulfonate-type water-based polyurethane is coated between the base layer (1) and the polishing layer (3), and heated and cured. After cutting and polishing, a water-based polyurethane composite porous polishing pad is prepared.

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