A wear-resistant phenolic resin and preparation method and application in sandpaper

Abstract

The invention belongs to the technical field of phenolic resins, and discloses a wear-resistant phenolic resin, a preparation method and an application of the wear-resistant phenolic resin in sandpaper. The wear-resistant phenolic resin comprises 100 parts by weight of phenolic resin, 5-25 parts by weight of isocyanate-based fluorine-containing hyperbranched polyimide and 1-1.5 parts by weight of a toughening agent; the hyperbranched polyimide has a dendritic three-dimensional molecular chain structure, high mechanical strength and strong wear resistance, and contains an isocyanate group. During the thermal curing process, the isocyanate group reacts with the phenolic hydroxyl group of the phenolic resin and the hydroxyl group of the toughening agent polyethylene glycol, so that the three are chemically cross-linked, the interface bonding performance of the fluorine-containing hyperbranched polyimide, the toughening agent polyethylene glycol and the phenolic resin is enhanced, the mechanical strength, wear resistance and water resistance of the phenolic resin cured product are improved under the synergistic effect, and the phenolic resin has better practical application in the adhesive for sandpaper.

Description

Technical Field

[0001] The invention belongs to the technical field of phenolic resins, in particular to a wear-resistant phenolic resin and a preparation method thereof and application in sandpaper. Background Art

[0002] Sandpaper mainly uses adhesives to bond the base paper and abrasives, so the performance of the adhesive has a great influence on the wear resistance and water resistance of sandpaper. The current adhesive for sandpaper is mainly phenolic resin, which has good bonding properties, high temperature resistance and chemical resistance, and has small shrinkage when hardening and high dimensional stability; improving the mechanical strength, wear resistance and water resistance of phenolic resin can make phenolic resin-based sandpaper have better performance.

[0003] Adding high-performance additives, such as high molecular polymers, inorganic materials, etc., to phenolic resin can improve its toughness, strength and other properties. Patent CN103980852B discloses a method for preparing a high-temperature resistant polyformaldehyde phenolic resin for coated abrasives. Using ethylene-vinyl acetate copolymer, polyphenylene ether resin powder, composite rare earth, cashew nut shell oil and the like as additives, the obtained phenolic resin-based sandpaper has the advantages of being soft and folding-resistant, but the patent does not improve the wear resistance and water resistance of phenolic resin. Polyimide is a special engineering material with high strength, high wear resistance and strong water resistance; it has broad application prospects in phenolic resin, epoxy resin and other materials, and can improve the mechanical and wear resistance of materials. Summary of the invention

[0004] The invention solves the problems that the phenolic resin glue for sandpaper has poor wear resistance and water resistance and low strength.

[0005] The technical scheme of the invention is: a wear-resistant phenolic resin, comprising 100 parts by weight of phenolic resin, 5-25 parts by weight of isocyanate-based fluorine-containing hyperbranched polyimide and 1-1.5 parts by weight of toughening agent polyethylene glycol 600-1000.

[0006] The preparation method of isocyanate-based fluorinated hyperbranched polyimide is as follows:

[0007] Step (1), in a nitrogen atmosphere, add trifluoromethyl triphenylamine monomer to N, N-dimethylacetamide, stir to dissolve, then drop N, N-dimethylacetamide solution containing 4, 4'-biphenyl ether dianhydride, stir to react at room temperature for 18-24 hours, then add pyridine and acetic anhydride, stir for 1-2 hours, heat to 50-60° C., stir to react for 6-10 hours, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain a soluble fluorine-containing hyperbranched polyimide.

[0008] The trifluoromethyltriphenylamine monomer has the structural formula (I) as follows:

[0009]

[0010] Step (2), adding a soluble fluorine-containing hyperbranched polyimide to N,N-dimethylacetamide, stirring to dissolve, adding tin tetrachloride and chloroethyl isocyanate in a nitrogen atmosphere, pouring the solution into acetone after the reaction to precipitate, filtering, washing with acetone, and drying to obtain an isocyanate-based fluorine-containing hyperbranched polyimide.

[0011] Preferably, in step (1), the molar ratio of trifluoromethyltriphenylamine monomer, 4,4'-biphenyl ether dianhydride, pyridine and acetic anhydride is 1:(1.4-1.6):(10-14):(18-25).

[0012] Preferably, in step (2), the soluble fluorine-containing hyperbranched polyimide is stirred and dissolved, and tin tetrachloride and chloroethyl isocyanate are added in a nitrogen atmosphere in a mass ratio of 1:(1.1-2.8):(0.6-1.5).

[0013] Preferably, in step (2), the reaction temperature is 55-70° C. and the reaction time is 18-24 h.

[0014] Preferably, in step (2), the preparation method of trifluoromethyltriphenylamine monomer is:

[0015] Step A, adding 3-nitro-5-(trifluoromethyl)aniline, triethylamine and trimesoyl chloride in a molar ratio of (3-3.3):(3-3.6):1 to dichloromethane, reacting at room temperature for 12-18 hours, distilling the solution under reduced pressure, washing with water, and recrystallizing the product in chloroform to obtain trifluoromethyl trinitrobenzene monomer.

[0016] Step B, adding trifluoromethyl trinitrobenzene monomer, hydrazine hydrate, and Pd / C catalyst in a mass ratio of 1: (0.82-0.88): (0.06-0.07) to ethanol, heating to 75-80° C., condensing and refluxing for 24-36 hours, filtering, distilling the filtrate under reduced pressure, washing with water, and recrystallizing the product in chloroform to obtain trifluoromethyl triphenylamine monomer.

[0017] Preferably, the preparation method of the wear-resistant phenolic resin is as follows: phenolic resin and toughening agent polyethylene glycol 600-1000 are added to toluene, stirred to dissolve, and then isocyanate-based fluorine-containing hyperbranched polyimide is added and mixed to obtain the wear-resistant phenolic resin.

[0018] Preferably, the wear-resistant phenolic resin is used in sandpaper.

[0019] The present invention has the following technical effects: the present invention carries out amidation reaction and reduction reaction on 3-nitro-5-(trifluoromethyl)aniline and trimesoyl chloride to obtain a novel trifluoromethyl triphenylamine monomer, which contains three amino groups, and carries out hyperbranched polymerization reaction with 4,4'-biphenyl ether dianhydride to obtain a soluble fluorine-containing hyperbranched polyimide. The hyperbranched polyimide contains a large number of trifluoromethyl groups and flexible ether bonds, which can improve the flexibility of the hyperbranched polyimide molecular chain, increase the free volume between the molecular chains, facilitate the insertion of organic solvents into the molecular chains, thereby improving the solubility of the hyperbranched polyimide, having good solubility in solvents such as N,N-dimethylacetamide, and facilitating Friedel-Crafts alkylation reaction with chloroethyl isocyanate, thereby introducing a large number of isocyanate groups into the molecular chain of the hyperbranched polyimide to obtain an isocyanate-based fluorine-containing hyperbranched polyimide.

[0020] The present invention adds isocyanate-based fluorine-containing hyperbranched polyimide to the phenolic resin, and the hyperbranched polyimide has a dendritic three-dimensional molecular chain structure, high mechanical strength, and strong wear resistance. In addition, the isocyanate group is contained, and in the heat curing process, the isocyanate group reacts with the phenolic hydroxyl group of the phenolic resin and the hydroxyl group of the toughening agent polyethylene glycol, so that the three are chemically cross-linked, and the interface bonding performance of the fluorine-containing hyperbranched polyimide, the toughening agent polyethylene glycol and the phenolic resin is enhanced, and the mechanical strength of the phenolic resin cured product is improved under the synergistic effect, showing better tensile strength and elongation at break, and reducing the friction and wear amount of the phenolic resin, so as to have better wear resistance.

[0021] The isocyanate-based fluorine-containing hyperbranched polyimide of the present invention undergoes a curing and crosslinking reaction with a phenolic resin to form a tight crosslinking network in the phenolic resin matrix, which can inhibit water molecules from entering the cured product matrix. In addition, the hyperbranched polyimide contains hydrophobic fluorine-containing groups, which can improve the hydrophobicity of the phenolic resin cured product, thereby reducing its water absorption rate, which is beneficial to improving water resistance, and enabling the phenolic resin to have better practical application in the adhesive for sandpaper. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the reaction formula for preparing trifluoromethyltriphenylamine monomer.

[0023] Figure 2 It is a reaction formula for preparing soluble fluorine-containing hyperbranched polyimide.

[0024] Figure 3 It is the reaction formula for preparing isocyanate-based fluorinated hyperbranched polyimide. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present disclosure clearer, the technical solution of the present disclosure will be clearly and completely described in combination with the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be arbitrarily combined with each other without conflict.

[0026] Example 1

[0027] (1) Add 26.4 mmol 3-nitro-5-(trifluoromethyl)aniline (CAS registration number 401-94-5), 28.8 mmol triethylamine, and 8 mmol trimesoyl chloride (CAS registration number 4422-95-1) to 80 mL of dichloromethane, and react at room temperature for 12 hours. Distill the solution under reduced pressure, wash with water, and recrystallize the product in chloroform to obtain trifluoromethyl trinitrobenzene monomer.

[0028] (2) Add 5 g of trifluoromethyl trinitrobenzene monomer, 4.1 g of hydrazine hydrate (mass fraction 80%), and 0.35 g of Pd / C catalyst to 70 mL of ethanol, heat to 75° C., condense and reflux for 36 h, filter, distill the filtrate under reduced pressure, wash with water, and recrystallize the product in chloroform to obtain trifluoromethyl triphenylamine monomer.

[0029] (3) In a nitrogen atmosphere, add 10 mmol trifluoromethyl triphenylamine monomer to 60 mL N,N-dimethylacetamide, stir to dissolve, then add dropwise 40 mL N,N-dimethylacetamide solution containing 15 mmol 4,4'-biphenyl ether dianhydride, stir to react at room temperature for 18 h, then add 120 mmol pyridine and 250 mmol acetic anhydride, stir for 2 h, heat to 60 ° C, stir to react for 6 h, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain a soluble fluorine-containing hyperbranched polyimide.

[0030] (4) Add 10 g of soluble fluorinated hyperbranched polyimide to 800 mL of N,N-dimethylacetamide, stir to dissolve, and add 18 g of tin tetrachloride (SnCl) in a nitrogen atmosphere. 4 ), 15g of chloroethyl isocyanate (CAS registration number 1943-83-5), heated to 70°C, reacted for 18h, poured the solution into acetone to precipitate the precipitate, filtered, washed with acetone, and dried to obtain isocyanate-based fluorine-containing hyperbranched polyimide.

[0031] (5) Add 100 g of phenolic resin and 1 g of toughening agent polyethylene glycol 600 to 200 mL of toluene, stir to dissolve, then add 5 g of isocyanate-based fluorinated hyperbranched polyimide and mix well to obtain a wear-resistant phenolic resin.

[0032] Example 2

[0033] (1) Add 24 mmol 3-nitro-5-(trifluoromethyl)aniline, 24 mmol triethylamine, and 8 mmol trimesoyl chloride to 60 mL dichloromethane, and react at room temperature for 18 h. Distill the solution under reduced pressure, wash with water, and recrystallize the product in chloroform to obtain trifluoromethyl trinitrobenzene monomer.

[0034] (2) Add 5 g of trifluoromethyl trinitrobenzene monomer, 4.4 g of hydrazine hydrate (mass fraction 80%), and 0.3 g of Pd / C catalyst to 60 mL of ethanol, heat to 80° C., condense and reflux for 24 h, filter, distill the filtrate under reduced pressure, wash with water, and recrystallize the product in chloroform to obtain trifluoromethyl triphenylamine monomer.

[0035] (3) In a nitrogen atmosphere, add 10 mmol trifluoromethyl triphenylamine monomer to 60 mL N,N-dimethylacetamide, stir to dissolve, then add dropwise 40 mL N,N-dimethylacetamide solution containing 14 mmol 4,4'-biphenyl ether dianhydride, stir to react at room temperature for 24 h, then add 140 mmol pyridine and 250 mmol acetic anhydride, stir for 1 h, heat to 60 ° C, stir to react for 6 h, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain a soluble fluorine-containing hyperbranched polyimide.

[0036] (4) Add 10 g of soluble fluorinated hyperbranched polyimide to 800 mL of N,N-dimethylacetamide, stir to dissolve, add 14 g of tin tetrachloride and 10 g of chloroethyl isocyanate in a nitrogen atmosphere, heat to 55 ° C, react for 24 hours, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain isocyanate-based fluorinated hyperbranched polyimide.

[0037] (5) Add 100 g of phenolic resin and 1.5 g of toughening agent polyethylene glycol 600 to 200 mL of toluene, stir to dissolve, then add 5 g of isocyanate-based fluorinated hyperbranched polyimide, mix well, and obtain a wear-resistant phenolic resin.

[0038] Example 3

[0039] (1) Add 25.2 mmol 3-nitro-5-(trifluoromethyl)aniline, 28.8 mmol triethylamine, and 8 mmol trimesoyl chloride to 80 mL dichloromethane, and react at room temperature for 18 h. Distill the solution under reduced pressure, wash with water, and recrystallize the product from chloroform to obtain trifluoromethyl trinitrobenzene monomer.

[0040] (2) Add 5 g of trifluoromethyl trinitrobenzene monomer, 4.2 g of hydrazine hydrate (mass fraction 80%), and 0.33 g of Pd / C catalyst to 60 mL of ethanol, heat to 75° C., condense and reflux for 36 h, filter, distill the filtrate under reduced pressure, wash with water, and recrystallize the product in chloroform to obtain trifluoromethyl triphenylamine monomer.

[0041] (3) In a nitrogen atmosphere, add 10 mmol trifluoromethyl triphenylamine monomer to 60 mL N,N-dimethylacetamide, stir to dissolve, then add dropwise 50 mL N,N-dimethylacetamide solution containing 16 mmol 4,4'-biphenyl ether dianhydride, stir and react at room temperature for 18 h, then add 100 mmol pyridine and 180 mmol acetic anhydride, stir for 2 h, heat to 50 ° C, stir and react for 10 h, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain a soluble fluorine-containing hyperbranched polyimide.

[0042] (4) Add 10 g of soluble fluorinated hyperbranched polyimide to 600 mL of N,N-dimethylacetamide, stir to dissolve, add 11 g of tin tetrachloride and 6 g of chloroethyl isocyanate in a nitrogen atmosphere, heat to 60°C, react for 18 h, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain isocyanate-based fluorinated hyperbranched polyimide.

[0043] (5) Add 100 g of phenolic resin and 1.5 g of toughening agent polyethylene glycol 1000 into 200 mL of toluene, stir to dissolve, then add 5 g of isocyanate-based fluorinated hyperbranched polyimide, mix well, and obtain a wear-resistant phenolic resin.

[0044] Comparative Example 1

[0045] The difference between this comparative example and Example 1 is that no isocyanate-based fluorine-containing hyperbranched polyimide is added to the phenolic resin.

[0046] (1) Add 100 g of phenolic resin and 1 g of toughening agent polyethylene glycol 600 into 200 mL of toluene, stir to dissolve, and mix well to obtain a wear-resistant phenolic resin.

[0047] Comparative Example 2

[0048] The difference between this comparative example and Example 1 is that the isocyanate-based fluorine-containing hyperbranched polyimide is replaced by a soluble fluorine-containing hyperbranched polyimide.

[0049] (1) Add 100 g of phenolic resin and 1 g of toughening agent polyethylene glycol 600 into 200 mL of toluene, stir to dissolve, then add 5 g of soluble fluorine-containing hyperbranched polyimide and mix well to obtain a wear-resistant phenolic resin.

[0050] Comparative Example 3

[0051] (1) According to the method of the article "Synthesis and Characterization of Polyimide Membrane Materials Based on Phenyl Ether-Type Fluorinated Diamines" in the journal "Journal of Polymer Science", Issue 1, January 2010, 4,4'-bis(4-amino-2-trifluoromethylphenoxy)diphenyl ether was prepared. The structural formula is as follows:

[0052]

[0053] (2) In a nitrogen atmosphere, add 15 mmol 4,4'-bis(4-amino-2-trifluoromethylphenoxy)diphenyl ether to 60 mL N,N-dimethylacetamide, stir to dissolve, then add dropwise 40 mL N,N-dimethylacetamide solution containing 15 mmol 4,4'-biphenyl ether dianhydride, stir to react at room temperature for 18 h, then add 120 mmol pyridine and 250 mmol acetic anhydride, stir for 2 h, heat to 60°C, stir to react for 6 h, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain a soluble fluorinated polyimide;

[0054] (3) Add 10 g of soluble fluorinated polyimide to 800 mL of N,N-dimethylacetamide, stir to dissolve, add 18 g of tin tetrachloride and 15 g of chloroethyl isocyanate in a nitrogen atmosphere, heat to 70°C, react for 18 h, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain isocyanate-modified fluorinated polyimide.

[0055] (4) Add 100 g of phenolic resin and 1 g of toughening agent polyethylene glycol 600 to 200 mL of toluene, stir to dissolve, then add 5 g of isocyanate-modified fluorinated polyimide and mix well to obtain a wear-resistant phenolic resin.

[0056] Comparative Example 4

[0057] (1) In a nitrogen atmosphere, add 10 mmol 1,3,5-tri(4-aminophenyl)benzene (structural formula: CAS registration number is 118727-34-7), after stirring and dissolving, 40 mL of N, N-dimethylacetamide solution containing 15 mmol 4, 4'-biphenyl ether dianhydride is added dropwise, and the reaction is stirred for 18 hours at room temperature, and then 120 mmol pyridine and 250 mmol acetic anhydride are added, stirred for 2 hours, and then heated to 60 ° C., stirred for 6 hours, and the solution is poured into acetone to precipitate the precipitate, which is filtered, washed with acetone, and dried to obtain a hyperbranched polyimide.

[0058] (2) Add 10 g of hyperbranched polyimide to 800 mL of N,N-dimethylacetamide, stir, then add 18 g of tin tetrachloride and 15 g of chloroethyl isocyanate in a nitrogen atmosphere, heat to 70 ° C, react for 18 hours, pour the solution into acetone to precipitate, filter, wash with acetone, and dry to obtain a modified hyperbranched polyimide.

[0059] (3) Add 100 g of phenolic resin and 1 g of toughening agent polyethylene glycol 600 into 200 mL of toluene, stir to dissolve, then add 5 g of modified hyperbranched polyimide and mix well to obtain a wear-resistant phenolic resin.

[0060] The wear-resistant phenolic resin is cast into a mold, vacuum degassed, placed in an oven, first heat-cured at 80°C for 6 hours, and then cured at 150°C for 2 hours to prepare a phenolic resin cured product.

[0061] The phenolic resin cured product was made into a sample of 10cm×10cm×0.4cm and weighed, recorded as m 0 Then soak it in water for 24 hours, take out the film, wipe the surface moisture, weigh it, and record it as m 1 ; Calculate the water absorption rate W. W=(m 1 -m 0 ) / m 0 ×100%.

[0062] The tensile properties of phenolic resin cured products were tested using a universal testing machine according to the method of GB / T 2567-2021.

[0063] The friction and wear performance of phenolic resin cured material was tested using a wear tester. The friction pair was 45# steel, the load value was 200N, the speed was 300r / min, the wear time was 30h, the mass before and after wear was weighed, and the wear amount △m was calculated, △m=M 1 -M 0 The test results are shown in Table 1.

[0064] Table 1 Performance test of phenolic resin cured product

[0065]

[0066] As shown in Table 1, isocyanate-based fluorine-containing hyperbranched polyimide is added to the phenolic resin of Examples 1, 2, and 3. The hyperbranched polyimide has a dendritic three-dimensional molecular chain structure, high mechanical strength, strong wear resistance, and contains isocyanate groups. During the thermal curing process, the isocyanate groups react with the phenolic hydroxyl group of the phenolic resin and the hydroxyl group of the toughening agent polyethylene glycol, thereby chemically crosslinking the three, enhancing the interface bonding performance of the fluorine-containing hyperbranched polyimide, the toughening agent polyethylene glycol and the phenolic resin, and improving the mechanical strength of the phenolic resin cured product under the synergistic effect, showing better tensile strength and elongation at break, and reducing the friction and wear of the phenolic resin, so as to achieve better wear resistance.

[0067] The isocyanate-based fluorinated hyperbranched polyimide undergoes a curing and cross-linking reaction with the phenolic resin to form a tight cross-linking network in the phenolic resin matrix, which can inhibit water molecules from entering the cured matrix. In addition, the hyperbranched polyimide contains hydrophobic fluorinated groups, which can improve the hydrophobicity of the phenolic resin cured product, thereby reducing its water absorption rate, which is beneficial to improving water resistance and enabling the phenolic resin to have better practical applications in sandpaper adhesives.

[0068] The phenolic resin of Comparative Example 1 does not contain isocyanate-based fluorine-containing hyperbranched polyimide, and the cured product has poor mechanical properties, low tensile strength and elongation at break, large friction and wear, poor wear resistance, high water absorption, and poor water resistance.

[0069] The soluble fluorine-containing hyperbranched polyimide of Comparative Example 2 does not contain isocyanate groups and cannot undergo curing and crosslinking reactions with phenolic resin and toughening agent polyethylene glycol. The compatibility between hyperbranched polyimide and phenolic resin is poor, making it difficult to effectively improve the mechanical properties and wear resistance of the phenolic resin.

[0070] In Comparative Example 3, 4,4'-bis(4-amino-2-trifluoromethylphenoxy)diphenyl ether is used as a diamine monomer to carry out a polymerization reaction with 4,4'-biphenyl ether dianhydride. The obtained soluble fluorinated polyimide has a linear molecular chain structure and does not contain a hyperbranched structure of a dendritic three-dimensional molecular chain. The reinforcing effect on the phenolic resin is low, resulting in lower mechanical properties and wear resistance than Example 1, and a water absorption rate greater than Example 1.

[0071] Comparative Example 4 uses 1,3,5-tri(4-aminophenyl)benzene as a triamine monomer and reacts it with 4,4'-biphenyl ether dianhydride to obtain a hyperbranched polyimide, but it does not contain a fluorine-containing group, has poor solubility, is difficult to dissolve in N,N-dimethylacetamide, does not undergo a good Friedel-Crafts alkylation reaction with chloroethyl isocyanate, and cannot effectively introduce isocyanate groups into the molecular chain of the hyperbranched polyimide, resulting in poor crosslinking performance of the hyperbranched polyimide with phenolic resin and polyethylene glycol, poor compatibility, and difficulty in effectively improving the mechanical properties and wear resistance of the phenolic resin cured product. In addition, the water absorption rate is greater than that of Example 1, and the water resistance is poor.

[0072] Taking Example 1 as an example, the amount of isocyanate-based fluorinated hyperbranched polyimide (FPI) is controlled to be 10-25 g.

[0073] (1) Add 100 g of phenolic resin and 1 g of toughening agent polyethylene glycol 600 into 200 mL of toluene, stir to dissolve, then add 5 g of isocyanate-based fluorinated hyperbranched polyimide and mix well to obtain a wear-resistant phenolic resin.

[0074] The wear-resistant phenolic resin is cast into a mold, vacuum degassed, placed in an oven, first heat-cured at 80°C for 6 hours, and then cured at 150°C for 2 hours to prepare a phenolic resin cured product.

[0075] The performance test was carried out according to the above method, and the results are shown in Table 2.

[0076] Table 2 Performance test of wear-resistant phenolic resin

[0077]

[0078] It can be seen from Table 2 that with the gradual increase in the amount of isocyanate-based fluorine-containing hyperbranched polyimide, the wear-resistant phenolic resin still exhibits higher tensile strength and elongation at break, as well as lower water absorption and wear, good mechanical properties, high wear resistance and excellent water resistance.

[0079] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure is described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A wear-resistant phenolic resin, characterized in that: The wear-resistant phenolic resin comprises 100 parts by weight of phenolic resin, 5-25 parts by weight of isocyanate-based fluorine-containing hyperbranched polyimide and 1-1.5 parts by weight of toughening agent; The preparation method of the isocyanate-based fluorinated hyperbranched polyimide is as follows: Step (1), in a nitrogen atmosphere, adding trifluoromethyl triphenylamine monomer to N, N-dimethylacetamide, stirring and dissolving, and then dropping N, N-dimethylacetamide solution containing 4, 4'-biphenyl ether dianhydride, stirring and reacting at room temperature for 18-24 hours, then adding pyridine and acetic anhydride, stirring for 1-2 hours, then heating to 50-60° C., stirring and reacting for 6-10 hours, pouring the solution into acetone to precipitate a precipitate, filtering, washing with acetone, and drying to obtain a soluble fluorine-containing hyperbranched polyimide; The trifluoromethyltriphenylamine monomer has the structural formula (I) as follows: Step (2), adding a soluble fluorine-containing hyperbranched polyimide to N,N-dimethylacetamide, stirring to dissolve, adding tin tetrachloride and chloroethyl isocyanate in a nitrogen atmosphere, pouring the solution into acetone after the reaction to precipitate, filtering, washing, and drying to obtain an isocyanate-based fluorine-containing hyperbranched polyimide.

2. The wear-resistant phenolic resin according to claim 1, characterized in that: The toughening agent is polyethylene glycol with a molecular weight of 600-1000.

3. The wear-resistant phenolic resin according to claim 1, characterized in that: In the step (1), the molar ratio of trifluoromethyl triphenylamine monomer, 4,4'-biphenyl ether dianhydride, pyridine and acetic anhydride is 1:(1.4-1.6):(10-14):(18-25).

4. The wear-resistant phenolic resin according to claim 1, characterized in that: In the step (2), the soluble fluorine-containing hyperbranched polyimide is stirred and dissolved, and tin tetrachloride and chloroethyl isocyanate are added in a nitrogen atmosphere in a mass ratio of 1:(1.1-2.8):(0.6-1.5).

5. The wear-resistant phenolic resin according to claim 1, characterized in that: In the step (2), the reaction temperature is 55-70° C. and the reaction time is 18-24 h.

6. The wear-resistant phenolic resin according to claim 1, characterized in that: In the step (2), the preparation method of trifluoromethyltriphenylamine monomer is: Step A, adding 3-nitro-5-(trifluoromethyl)aniline, triethylamine and trimesoyl chloride to dichloromethane, reacting at room temperature for 12-18 hours, distilling the solution under reduced pressure, washing, and recrystallizing to obtain trifluoromethyl trinitrobenzene monomer; Step B, adding trifluoromethyl trinitrobenzene monomer, hydrazine hydrate, and Pd / C catalyst to ethanol, heating to 75-80° C., condensing and refluxing for 24-36 hours, filtering, distilling the filtrate under reduced pressure, washing, and recrystallizing to obtain trifluoromethyl triphenylamine monomer.

7. The wear-resistant phenolic resin according to claim 6, characterized in that: In step A, the molar ratio of 3-nitro-5-(trifluoromethyl)aniline, triethylamine and trimesoyl chloride is (3-3.3):(3-3.6):

1.

8. The wear-resistant phenolic resin according to claim 6, characterized in that: In the step B, the mass ratio of trifluoromethyl trinitrobenzene monomer, hydrazine hydrate, and Pd / C catalyst is 1:(0.82-0.88):(0.06-0.07).

9. A method for preparing a wear-resistant phenolic resin according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: adding phenolic resin and toughening agent into toluene, stirring and dissolving the mixture, and then adding isocyanate-based fluorine-containing hyperbranched polyimide and mixing the mixture to obtain the wear-resistant phenolic resin.

10. Use of the wear-resistant phenolic resin obtained by the preparation method according to claim 9 in sandpaper.

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