Environment-friendly recyclable polyurethane polishing pad and preparation method thereof

Abstract

The invention discloses an environment-friendly recyclable polyurethane polishing pad and a preparation method thereof, and relates to the technical field of polyurethane polishing pads. According to the invention, the comprehensive performance of the polyurethane prepared by compounding multiple polyols is obviously improved; the inorganic filler nano silicon nitride is added, so that the mechanical removal efficiency of the polishing pad on hard materials is improved; alkane is used as a foaming agent, so that emission of volatile organic compounds is avoided, and environmental protection is realized; the design of bionic tooth-shaped structure surface grooves is adopted, the flowing efficiency of polishing liquid is improved, residues of abrasive particles and abrasive dust in a working area are reduced, and therefore the polishing quality is improved; according to the branched isocyanate disclosed by the invention, the risk of environmental pollution caused by volatile organic compounds in the production process is greatly reduced, the toxicity of polyurethane is reduced, the chemical stability is higher, and the tensile strength of the material is improved; the characteristics of covalent bonds and dynamic covalent bonds are beneficial to physical recovery or chemical recovery, resource reutilization is realized, and waste pollution is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane polishing pads, in particular to an environmentally friendly and recyclable polyurethane polishing pad and a preparation method thereof. BACKGROUND

[0002] Chemical mechanical polishing (CMP) is a surface planarization process combining chemical and mechanical action, by placing the workpiece on the polishing pad, using the friction between the abrasive and the polishing pad, layer by layer removing the surface material, so as to achieve high flatness, low surface roughness, and a smooth surface. The polyurethane polishing pad takes polyurethane foam as the core substrate, adds curing agent, foaming agent or catalyst, or adds polishing liquid during polishing to improve polishing efficiency or enhance the performance of the polishing pad. However, the chemical reagents in the polishing liquid react with the polishing pad material, forming a glaze layer or debris embedded in the polishing pad micropores, which hardens after combining with chemical residues, blocking the pores and reducing the service life of the polishing pad. Traditional polyurethane polishing pads contain harmful substances such as halogen (such as chlorine, bromine, etc.), PFAS (perfluoro and polyfluoro alkyl substances), which are difficult to degrade and cause pollution.

[0003] Traditional polishing pads mostly use toluene diisocyanate (TDI) type polyurethane materials, which produce waste solids during production and are not environmentally friendly and cannot be recycled after use. With the continuous development of electronic products, 3C products and the semiconductor industry, the demand for polishing applications is increasing, and the demand for polyurethane polishing pads is growing. The present application introduces a new type of environmentally friendly and recyclable diphenyl methane diisocyanate (MDI) type polyurethane polishing pad and its preparation method to solve the above technical problems. SUMMARY

[0004] The present application aims to provide an environmentally friendly and recyclable polyurethane polishing pad and a preparation method thereof to solve the problems in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A preparation method of an environmentally friendly and recyclable polyurethane polishing pad, comprising the following processes:

[0007] S1: mixing polyether polyol, polycarbonate polyol and polyester polyol to obtain a mixture;

[0008] S2: adding branched isocyanate compound, foaming agent and inorganic filler to the mixture, and dispersing at a speed of 1200-2400 r / min for 30-40 min to obtain branched polyurethane prepolymer;

[0009] S3: The branched polyurethane prepolymer is injected into a mold, foamed at a temperature of 85-95 DEG C and a pressure of 7-15 MPa for 2-5 h to form a foamed polyurethane elastomer, gradient curing, slicing, to obtain an environmentally friendly recyclable polyurethane polishing pad.

[0010] Further, in step S3, the environmentally friendly recyclable polyurethane polishing pad is post-processed, and the post-processing process is: a groove-shaped structure is arranged on the surface of the polishing pad; the groove-shaped structure is a wave-tooth structure combined with a transition circular arc design extending outward from the center as a starting point.

[0011] Further, the groove depth is 0.5-1 mm, and the included angle of a single groove unit structure is 140-160 DEG.

[0012] Further, the inorganic filler is nano silicon nitride.

[0013] Further, the foaming agent is any one of n-pentane, i-pentane, and cyclopentane.

[0014] In the above technical effects, first, the polyurethane polishing pad has a unique soft segment-hard segment block structure, with polyols as the soft segment; branched isocyanate compounds as the hard segment, the hydroxyl group in the polyol reacts with the isocyanate group to form a urethane, and the polyurethane prepared by compounding multiple polyols has significantly improved comprehensive performance. The polyester polyol can improve the tensile strength and hardness, the polyether polyol imparts flexibility, its low viscosity characteristics can improve the flowability of the polyurethane system, making it easy to process and increasing the foaming stability, the polycarbonate polyol can improve the wear resistance and fatigue resistance, reducing the wear of the polishing pad, and meeting the performance requirements of high strength and high wear resistance of the chemical mechanical polishing (CMP) polishing pad.

[0015] Secondly, by adding the inorganic filler nano silicon nitride, the hardness of the nano silicon nitride is higher than that of the traditional filler, which can improve the mechanical removal efficiency of the polishing pad for hard materials, and the nano-sized particle size can form a more dense abrasive particle distribution, accelerating the material surface flattening through micro-cutting action; the elastomer polyurethane and the rigid structure of the nano silicon nitride produce a synergistic effect, the spherical or near-spherical structure of the nano silicon nitride can disperse mechanical stress, avoid local stress concentration, reduce the use of polishing liquid, reduce the residual of heavy metal pollutants in the polishing liquid, improve the polishing precision and polishing efficiency, and is more environmentally friendly and green.

[0016] Finally, the alkane is used as a foaming agent to replace the fluorine-containing foaming agent, the ODP of the alkane foaming agent is small, most of which is zero, and the GWP is small, which has less impact on the environment, avoids the emission of volatile organic compounds, and is green and environmentally friendly; the gradient curing technology is adopted to ensure the slow growth of the pores and avoid cracking and collapse, thereby improving the structural stability; the bionic cud animal tooth-shaped surface groove design is adopted, and the single groove unit is mostly obtuse or circular arc-shaped, which makes the contact surface force more uniform during polishing, reduces the wear and consumption of the polishing pad under the condition of not affecting the polishing efficiency, prolongs the service life of the polyurethane polishing pad; when the polishing liquid is used during processing, compared with the traditional non-groove design polyurethane polishing pad, the surface groove structure has higher polishing liquid flow efficiency, reduces the residue of abrasive particles and swarf in the working area, thereby improving the polishing quality, and the physical structure instead of the chemical composition regulation is more in line with the sustainable development strategy, thereby reducing the pollution to the environment.

[0017] Further, the branched isocyanate compound is prepared by the following process: adding dimethylformamide (DMF) to dissolve butanedione monoxime, adding diphenyl methane diisocyanate (MDI) to stir uniformly, then adding 1,4-butanediol and gallic acid, continuing to stir, pouring into a mold, drying at a temperature of 80-90℃ for 4-6h to obtain the branched isocyanate compound.

[0018] Further, the branched isocyanate compound comprises the following mass components: 2-3 parts of butanedione monoxime, 50-60 parts of DMF, 10-15 parts of MDI, 1-2 parts of 1,4-butanediol, and 1-2 parts of gallic acid.

[0019] In the above technical solution, the di-functional oxime compound is used as a chain extender, the hydroxyl group in the butanedione monoxime reacts with the isocyanate group to graft the oxime-urethane bond in the polyurethane molecular chain, the oxime-urethane bond can impart reversibility to the polyurethane, so that the polyurethane polishing pad can be reprocessed and recycled; a small amount of gallic acid is added, the phenolic hydroxyl group of the gallic acid as a natural phenolic chain extender can graft with the remaining isocyanate groups to form a phenolic-urethane bond, under the condition of heating or other external environmental intervention, the breakage of the phenolic-urethane bond will release free isocyanate groups (-NCO), which can then recombine with other hydroxyl groups (-OH) or amino groups (-NH2), having the characteristics of dynamic covalent bond, imparting self-repairing and recyclable ability, increasing the reprocessability of the polyurethane material, and enhancing the mechanical properties and oxidation resistance of the polyurethane material, thereby prolonging the service life of the polyurethane polishing pad; by introducing a diol as a chain extender, the small molecule can fully react with the polyurethane synthesis system, adjust the reaction viscosity, improve the regularity of the molecular structure and the molecular weight, and comprehensively improve the performance of the composite polyurethane polishing pad.

[0020] The branched isocyanate compound of the present application can effectively reduce the system reactivity, avoid the problem of uneven distribution of interface defects caused by the direct reaction of butanedione oxime and gallic acid as chain extenders in the traditional process, greatly reduce the risk of environmental pollution caused by volatile organic compounds in the production process compared with TDI, reduce the toxicity of polyurethane, have higher chemical stability, and improve the tensile strength of the material; the covalent bond and dynamic covalent bond characteristics are beneficial to physical recycling or chemical recycling, realize resource recycling, and reduce waste pollution.

[0021] Further, the molecular weight of the polyether polyol is 500-1000.

[0022] Further, the molecular weight of the polycarbonate polyol is 1000-2000.

[0023] Further, the molecular weight of the polyester polyol is 1000-2000.

[0024] Further, the branched polyurethane prepolymer comprises the following mass components: 10-20 parts of polyether polyol, 20-30 parts of polycarbonate polyol, 20-30 parts of polyester polyol, 70-80 parts of branched isocyanate compound, 40-50 parts of foaming agent, and 5-10 parts of inorganic filler.

[0025] Further, the process conditions of the gradient curing are as follows: heating to 65-75 DEG C, keeping for 30-40 min, then heating to 110-120 DEG C, and curing for 2-3 h.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] 1. The polyurethane polishing pad of the present application is prepared by compounding a plurality of polyols, has high tensile strength, good flexibility, good wear resistance and fatigue resistance, and by adding inorganic filler nano silicon nitride, the mechanical removal efficiency of the polishing pad for hard materials is improved, the material surface is accelerated to be planarized, the rigid structure of the elastomeric polyurethane and the nano silicon nitride produces a synergistic effect, the mechanical stress is dispersed, the use of polishing liquid is reduced, the residual of heavy metal pollutants in the polishing liquid is reduced, the polishing precision and polishing efficiency are improved, and the polishing pad is more environmentally friendly and green.

[0028] 2、The alkane is used as the foaming agent to replace the fluorine-containing foaming agent, volatile organic emissions are avoided, it is green and environment-friendly, the bionic animal tooth-shaped structure surface groove design is adopted, and the single groove unit is mostly an obtuse angle or a circular arc, so that the contact surface is more uniform in stress in the polishing process, the polishing efficiency is not affected, the wear and consumption of the polishing pad are reduced, the service life of the polyurethane polishing pad is prolonged, the surface groove structure has higher polishing liquid flow efficiency, the residual abrasive particles and swarf in the working area are reduced, and thus the polishing quality is increased, the physical structure is used to replace the chemical composition to regulate, which is more in line with the sustainable development strategy, and the pollution to the environment is reduced.

[0029] 3、The di-functional oxime compound is used as the chain extender, the hydroxyl group in the dimethylglyoxime reacts with the isocyanate group, the oxime-urethane bond is grafted in the polyurethane molecular chain, the oxime-urethane bond can endow the polyurethane with reversibility, the polyurethane polishing pad can be reprocessed and recycled, a small amount of gallic acid is added, the phenolic hydroxyl group can react with the remaining isocyanate group to form a phenol-urethane bond, the dynamic covalent bond characteristics are possessed, the self-repairing and recyclable ability are endowed, the reworkability of the polyurethane material is increased, and the mechanical properties and oxidation resistance of the polyurethane polishing pad are enhanced, so that the service life of the polyurethane polishing pad is prolonged. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0031] In the following specific embodiments, the "parts" are mass parts, except for special cases.

[0032] The polyether polyol is polytetrahydrofuran, and the molecular weight is 800;

[0033] The polycarbonate polyol is polycarbonate diol, and the molecular weight is 2000;

[0034] The polyester polyol is polycaprolactone polyol, and the CAS is 24980-41-4;

[0035] The MDI is MDI-50;

[0036] The nano silicon nitride is DK-Si3N4-01, the average particle size is 20 nm, and the purity is 99.9%;

[0037] The dimethylglyoxime is CAS:18180-30-8;

[0038] The gallic acid is CAS:149-91-7;

[0039] Embodiment 1:

[0040] The application discloses a preparation method of an environment-friendly and recyclable polyurethane polishing pad.

[0041] S1: mixing polyether polyol, polycarbonate polyol and polyester polyol to obtain a mixture;

[0042] S2: adding branched isocyanate compound, normal pentane and nano silicon nitride into the mixture, and performing high-speed dispersion at a rotating speed of 1200 r / min for 30 min to obtain branched polyurethane prepolymer;

[0043] S3: injecting the branched polyurethane prepolymer into a mold, foaming the branched polyurethane prepolymer at a temperature of 85 ℃ and a pressure of 7 MPa for 2 h to form a foamed polyurethane elastomer, increasing the temperature to 65 ℃ and maintaining for 30 min, then increasing the temperature to 110 ℃ and solidifying for 2 h, slicing and setting a groove-shaped structure on the surface of the polishing pad, wherein the groove-shaped structure is a wave-tooth-shaped structure combined with a transition arc design extending outward from the center as a starting point, to obtain the environment-friendly and recyclable polyurethane polishing pad; the groove depth is 0.5 mm, and the included angle of a single groove unit structure is 140°.

[0044] The branched isocyanate compound is prepared by the following process: adding dimethylglyoxime into N,N-dimethylformamide (DMF) to dissolve, adding MDI to stir uniformly, then adding 1,4-butanediol and gallic acid to continue stirring, and injecting into a mold to dry at a temperature of 80 ℃ for 4 h to obtain the branched isocyanate compound.

[0045] The branched isocyanate compound comprises the following mass components: 2 parts of dimethylglyoxime, 50 parts of DMF, 10 parts of MDI, 1 part of 1,4-butanediol and 1 part of gallic acid.

[0046] The branched polyurethane prepolymer comprises the following mass components: 10 parts of polyether polyol, 20 parts of polycarbonate polyol, 20 parts of polyester polyol, 70 parts of branched polyurethane compound, 40 parts of normal pentane and 5 parts of nano silicon nitride.

[0047] Embodiment 2:

[0048] The application discloses a preparation method of an environment-friendly and recyclable polyurethane polishing pad.

[0049] S1: mixing polyether polyol, polycarbonate polyol and polyester polyol to obtain a mixture;

[0050] S2: adding MDI, cyclopentane and nano silicon nitride into the mixture, and performing high-speed dispersion at a rotating speed of 1200 r / min for 30 min to obtain branched polyurethane prepolymer;

[0051] S3: The branched polyurethane prepolymer is injected into a mold, foamed at a temperature of 85℃ and a pressure of 7MPa for 2h, heated to 65℃ and kept for 30min, then heated to 110℃ and cured for 2h, sliced, and a groove-shaped structure is arranged on the surface of the polishing pad; the groove-shaped structure is a wave-tooth structure combined with a transition arc design that expands outward from the center, to obtain an environmentally friendly and recyclable polyurethane polishing pad; the groove depth is 0.5mm, and the included angle of a single groove unit structure is 150°;

[0052] The branched isocyanate compound is prepared by the following process: butanedione oxime is dissolved in DMF, MDI is added and stirred uniformly, then 1,4-butanediol and gallic acid are added and stirred continuously, and the branched isocyanate compound is obtained by injecting into a mold and drying at a temperature of 80℃ for 4h;

[0053] The branched isocyanate compound includes the following mass components: 2.5 parts of butanedione oxime, 55 parts of DMF, 12 parts of MDI, 1 part of 1,4-butanediol, and 1 part of gallic acid;

[0054] The branched polyurethane prepolymer includes the following mass components: 15 parts of polyether polyol, 25 parts of polycarbonate polyol, 25 parts of polyester polyol, 75 parts of branched isocyanate compound, 45 parts of cyclopentane, and 8 parts of nano silicon nitride.

[0055] Example 3:

[0056] A preparation method of an environmentally friendly and recyclable polyurethane polishing pad, including the following processes:

[0057] S1: Polyether polyol, polycarbonate polyol, and polyester polyol are mixed to obtain a mixture;

[0058] S2: MDI is added to the mixture, isopentane and nano silicon nitride are added, and high-speed dispersion is performed at a speed of 2400r / min for 40min to obtain a branched polyurethane prepolymer;

[0059] S3: The branched polyurethane prepolymer is injected into a mold, foamed at a temperature of 95℃ and a pressure of 15MPa for 5h, heated to 75℃ and kept for 40min, then heated to 120℃ and cured for 3h, sliced, and a groove-shaped structure is arranged on the surface of the polishing pad; the groove-shaped structure is a wave-tooth structure combined with a transition arc design that expands outward from the center, to obtain an environmentally friendly and recyclable polyurethane polishing pad; the groove depth is 1mm, and the included angle of a single groove unit structure is 160°;

[0060] The branched isocyanate compound is prepared by the following process: butanedione oxime is dissolved in DMF, MDI is added and stirred uniformly, then 1,4-butanediol and gallic acid are added, and stirring is continued, the mold is injected, and drying is carried out at a temperature of 90°C for 6h to obtain the branched isocyanate compound;

[0061] The branched isocyanate compound includes the following mass components: 3 parts of butanedione oxime, 60 parts of DMF, 15 parts of MDI, 2 parts of 1,4-butanediol, and 2 parts of gallic acid;

[0062] The branched polyurethane prepolymer includes the following mass components: 20 parts of polyether polyol, 30 parts of polycarbonate polyol, 30 parts of polyester polyol, 80 parts of branched isocyanate compound, 50 parts of isopentane, and 10 parts of nano silicon nitride.

[0063] Comparative Example 1:

[0064] The present comparative example provides a preparation method of an environmentally friendly recyclable polyurethane polishing pad, including the following process:

[0065] S1: The polyether polyol and the branched polyurethane compound are mixed uniformly, then the foaming agent and the inorganic filler are added, and high-speed dispersion is carried out at a speed of 1200r / min for 30min to obtain the branched polyurethane prepolymer;

[0066] S2: The branched polyurethane prepolymer is injected into the mold, foaming is carried out at a temperature of 85°C and a pressure of 7MPa for 2h to form a foamed polyurethane elastomer, gradient curing is carried out, slicing is carried out, and an environmentally friendly recyclable polyurethane polishing pad is obtained, and the remaining method is the same as that of Example 1.

[0067] Comparative Example 2:

[0068] The present comparative example provides a preparation method of an environmentally friendly recyclable polyurethane polishing pad, and the polyurethane prepolymer includes the following mass components: 10 parts of polyether polyol, 20 parts of polycarbonate polyol, 20 parts of polyester polyol, 70 parts of MDI, 40 parts of n-pentane, and 5 parts of nano silicon nitride, and the remaining method is the same as that of Example 1.

[0069] Comparative Example 3:

[0070] The present comparative example provides a preparation method of an environmentally friendly recyclable polyurethane polishing pad, including the following process:

[0071] S1: The polyether polyol, the polycarbonate polyol, and the polyester polyol are mixed to obtain a mixture;

[0072] S2: MDI and butanedione oxime are added to the mixture and mixed uniformly, then the foaming agent and the inorganic filler are added, and high-speed dispersion is carried out at a speed of 1200r / min for 30min to obtain the polyurethane prepolymer;

[0073] S3: The polyurethane prepolymer was injected into a mold, foamed at a temperature of 85℃ and a pressure of 7MPa for 2h to form a foamed polyurethane elastomer, gradient curing, slicing to obtain a polyurethane polishing pad, and the rest of the methods were the same as in Example 1.

[0074] Comparative Example 4:

[0075] The present comparative example provides a preparation method of an environmentally friendly and recyclable polyurethane polishing pad, comprising the following processes:

[0076] S1: The polyether polyol, polycarbonate polyol and polyester polyol were mixed to obtain a mixture;

[0077] S2: The MDI and gallic acid were added to the mixture and mixed uniformly, then the foaming agent and inorganic filler were added, and high-speed dispersion was carried out at a speed of 1200r / min for 30min to obtain a polyurethane prepolymer;

[0078] S3: The polyurethane prepolymer was injected into a mold, foamed at a temperature of 85℃ and a pressure of 7MPa for 2h to form a foamed polyurethane elastomer, gradient curing, slicing to obtain a polyurethane polishing pad, and the rest of the methods were the same as in Example 1.

[0079] Experiment:

[0080] The samples obtained in Examples 1-3 and Comparative Examples 1-4 were taken, and their properties were detected and the detection results were recorded:

[0081] Tensile strength test: GB / T 528-2009 was used as a reference standard, an electronic universal testing machine was used, and the sample was tested at a tensile speed of 150mm / min at room temperature, and the tensile strength was recorded;

[0082] Thermal gravimetric test: GB / T 27761-2011 was used as a reference standard, a thermal gravimetric analyzer was used for testing, and under the protection of nitrogen atmosphere, the temperature was raised to 450℃ at a rate of 10℃ / min, and the weight loss was tested;

[0083] Compression rate test: T / JSQA 157-2023 was used as a reference standard, the sample was placed on the platen, a load of 235.5g was applied, and the initial thickness was recorded. The load was increased to 1413g, and the thickness after compression was recorded. The compression rate was calculated;

[0084] Self-repairing test: a surgical knife was used to draw a trace on the surface of the sample, an optical microscope was used to observe the scratch on the surface of the sample, the sample was placed in an oven at 90℃ for 10h, the tensile strength of the repaired sample was tested, and the self-repairing efficiency of the sample was calculated.

[0085] Cost performance comparison table

[0086] Index Tensile strength (MPa) Thermal weight loss (%) Compression rate (%) Self-repairing efficiency (%) Example 1 35.2 95.5 2.8 96.5 Example 2 37.6 94.2 4.3 97.6 Example 3 36.2 95.8 3.1 95.3 Comparative Example 1 35.3 93.5 4.6 82.1 Comparative Example 2 27.9 85.4 6.3 74.8 Comparative Example 3 31.2 91.4 5.1 79.9 Comparative Example 4 32.6 90.8 4.9 81.7

[0087] According to the data in the above table, the following conclusions can be clearly obtained:

[0088] The polyurethane polishing pad obtained in Examples 1-3 is compared with Comparative Examples 1-4, and the test results show that:

[0089] Compared with the comparative examples, the polyurethane polishing pad obtained in Examples 1-3 has high tensile strength, high thermal weight loss ratio, low compression rate and high self-repairing efficiency.

[0090] Compared with Example 1, the polyurethane polishing pad obtained in Comparative Example 1 is prepared by using a single polyol and MDI, and the tensile strength is reduced and the compression rate is increased, which indicates that the use of a single polyol as a synthetic polyurethane material reduces the comprehensive performance of the polishing pad, and reflects the advantages of the use of multiple polyols in the present application.

[0091] Compared with Example 1, the polyurethane polishing pad obtained in Comparative Example 2 has reduced tensile strength, increased compression rate, reduced self-repairing efficiency and significantly reduced thermal weight loss, which indicates that the modification of MDI without reversible covalent bonds and dynamic covalent bonds significantly reduces the recyclability, and reflects the technical advantages of the modification of MDI in the present application.

[0092] Compared with Example 1, the polyurethane polishing pad obtained in Comparative Example 3 directly adds butanedione oxime as a chain extender to the branched polyurethane prepolymer, and compared with Comparative Example 2, the thermal weight loss is improved, but it is not as good as the effect of the graft modification of MDI in the present application.

[0093] Compared with Example 1, the polyurethane polishing pad obtained in Comparative Example 4 directly adds gallic acid as a chain extender to the branched polyurethane prepolymer, and the tensile strength is reduced, the compression rate is increased, the self-repairing efficiency is reduced, and compared with Comparative Example 2, the thermal weight loss is improved, but it is not as good as the effect of the graft modification of MDI in the present application.

[0094] In summary, the polyurethane polishing pad of the present application is prepared by using multiple polyols, has high tensile strength, high thermal weight loss ratio, high compression rate and high self-repairing efficiency, uses difunctional oxime compounds as chain extenders, the hydroxyl group in butanedione oxime reacts with the isocyanate group, the oxime-urethane bond is grafted in the polyurethane molecular chain, the oxime-urethane bond can impart reversibility to the polyurethane, and the gallic acid is compounded, the phenolic hydroxyl group can be grafted with the remaining isocyanate group to form a phenolic-urethane bond, which has the characteristics of dynamic covalent bond and recyclable processing performance, and meets the environmental protection, green and sustainable development strategy.

[0095] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A method for preparing an environmentally friendly and recyclable polyurethane polishing pad, characterized by: The process comprises the following steps: S1: mixing polyether polyol, polycarbonate polyol and polyester polyol to obtain a mixture; S2: adding branched isocyanate compound, foaming agent and inorganic filler to the mixture, and high-speed dispersing to obtain branched polyurethane prepolymer; S3: injecting the branched polyurethane prepolymer into a mold, foaming, forming a foamed polyurethane elastomer, gradient curing, slicing, and obtaining an environmentally friendly and recyclable polyurethane polishing pad.

2. The preparation method of the environment-friendly and recyclable polyurethane polishing pad according to claim 1, characterized in that: In step S3, the environmentally friendly and recyclable polyurethane polishing pad is subjected to post-treatment, and the post-treatment process is: setting a groove-shaped structure on the surface of the polishing pad; the groove-shaped structure is a wave-tooth-shaped structure combined with a transition circular arc design extending outward from the center as a starting point.

3. The preparation method of the environment-friendly and recyclable polyurethane polishing pad according to claim 1, characterized in that: The branched polyurethane prepolymer comprises the following mass components: 10-20 parts of polyether polyol, 20-30 parts of polycarbonate polyol, 20-30 parts of polyester polyol, 70-80 parts of branched isocyanate compound, 40-50 parts of foaming agent, and 5-10 parts of inorganic filler.

4. The preparation method of the environment-friendly and recyclable polyurethane polishing pad according to claim 1, characterized in that: The inorganic filler is nano silicon nitride, and the foaming agent is any one of n-pentane, iso-pentane and cyclopentane.

5. The preparation method of the environment-friendly and recyclable polyurethane polishing pad according to claim 1, characterized in that: The branched isocyanate compound is prepared by the following process: adding butanedione oxime into N,N-dimethylformamide, adding diphenyl methane diisocyanate and stirring uniformly, then adding 1,4-butanediol and gallic acid, continuing to stir, injecting into a mold, drying at a temperature of 80-90℃ for 4-6h to obtain the branched isocyanate compound.

6. The preparation method of the environment-friendly and recyclable polyurethane polishing pad according to claim 5, characterized in that: The branched isocyanate compound comprises the following mass components: 2-3 parts of butanedione oxime, 50-60 parts of N,N-dimethylformamide, 10-15 parts of diphenyl methane diisocyanate, 1-2 parts of 1,4-butanediol, and 1-2 parts of gallic acid.

7. The method of claim 1, wherein the method further comprises: adding a cross-linking agent to the mixture of the polyurethane prepolymer and the polyol; and mixing the cross-linking agent with the mixture of the polyurethane prepolymer and the polyol to form the polyurethane prepolymer mixture. The molecular weight of the polyether polyol is 500-1000, the molecular weight of the polyester polyol is 1000-2000, and the molecular weight of the polycarbonate polyol is 1000-2000.

8. The preparation method of the environment-friendly and recyclable polyurethane polishing pad according to claim 2, characterized in that: The groove depth is 0.5-1mm, and the included angle of a single groove unit structure is 140-160°.

9. The method for preparing an environmentally friendly and recyclable polyurethane polishing pad according to claim 1, characterized in that: The process conditions of the gradient curing are: heating to 65-75℃ and keeping for 30-40min, then heating to 110-120℃ and curing for 2-3h.

10. An environmentally friendly and recyclable polyurethane polishing pad, characterized by: The environmentally friendly and recyclable polyurethane polishing pad is prepared according to the preparation method of claim 1-9.