High-wear-resistance polyurethane material for sieve plate processing and preparation method of high-wear-resistance polyurethane material

Abstract

The invention discloses a high-wear-resistance polyurethane material for sieve plate processing and a preparation method of the high-wear-resistance polyurethane material, belongs to the technical field of polyurethane materials, and aims to solve the technical problem that the hardness, tensile strength, tear strength, wear resistance and flame retardance of a polyurethane material in the prior art need to be further improved. The polyurethane material is specifically prepared from the following components in parts by weight: 80-100 parts of modified polyurethane, 3-5 parts of NH2-rGO / MoSe2, 10-15 parts of modified nylon and 2-3 parts of an auxiliary additive, and the hardness, tensile strength, tear strength, wear resistance and flame retardance of the polyurethane material are further improved through hydroxyl-terminated polysiloxane, flame-retardant polyester, NH2-rGO / MoSe2 and modified nylon.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane materials, and particularly relates to a highly wear-resistant polyurethane material for sieve plate processing and a preparation method thereof. Background Art

[0002] In industrial fields such as mines, chemical industries, and building materials, as the core component for material screening, sieve plates need to withstand high-frequency vibrations, material impacts, and frictional wear for a long time, and may also face safety risks such as high temperatures and open flames. Due to the limitations of the molecular chain structure of traditional polyurethane materials, there are technical problems that the hardness, toughness, abrasion resistance, and flame retardancy need to be further improved.

[0003] Traditional polyurethanes rely on the cross-linking of polyether or polyester polyols with isocyanates to form a network, but the high flexibility of the molecular chain results in limited hardness and tensile strength, and plastic deformation or even fracture is likely to occur under high-frequency vibrations, shortening the service life.

[0004] At the same time, the abrasion of traditional polyurethanes mainly stems from the weak intermolecular forces, and chain segment slippage and interfacial debonding are likely to occur during the friction process. Although the introduction of nano-fillers, such as graphene, can improve the wear resistance, the uneven dispersion of the fillers or the insufficient interfacial bonding force leads to limited enhancement effect and may cause a decline in mechanical properties. Moreover, most industrial scenarios require sieve plate materials to have flame retardant properties. Polyurethane contains a large amount of hydrocarbon components and belongs to flammable materials. Common flame retardant solutions, such as adding halogen flame retardants, can improve the flame retardant grade, but will cause the deterioration of the mechanical properties of the material and release toxic gases during combustion, which does not meet the environmental protection requirements. Halogen-free flame retardant systems, such as phosphorus-nitrogen synergistic flame retardancy, are difficult to achieve the balance between flame retardant efficiency and mechanical properties due to poor compatibility with polyurethane. In addition, the performance improvement of filled polyurethanes highly depends on the interfacial bonding force between the filler and the matrix. Traditional nylon 66 has few polar groups and is prone to phase separation when blended with polyurethane, resulting in a "delamination" phenomenon in the composite material and a significant decline in mechanical properties.

[0005] In summary, a solution is proposed as follows. Summary of the Invention

[0006] The purpose of the present invention is to provide a highly wear-resistant polyurethane material for sieve plate processing and a preparation method thereof, aiming to solve the technical problems that the hardness, tensile strength, tear strength, wear resistance, and flame retardancy of polyurethane materials in the prior art need to be further improved.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A highly wear-resistant polyurethane material for sieve plate processing, comprising the following components by weight: 80 - 100 parts of modified polyurethane, 3 - 5 parts of NH2-rGO / MoSe2, 10 - 15 parts of modified nylon, and 2 - 3 parts of auxiliary additives;

[0008] The auxiliary additive includes the following components by weight: 8-12 parts of curing agent, 1-2 parts of antioxidant, and 3-5 parts of plasticizer;

[0009] The preparation method of the modified polyurethane is as follows: Poly(tetrahydrofuran) glycol, hydroxy-terminated polysiloxane, flame-retardant polyester, and catalyst are added to a reaction kettle containing N,N-dimethylformamide and stirred and mixed. Then, diphenylmethane diisocyanate and chain extender are added thereto. After the reaction is completed, a capping agent is finally added, and post-treatment is carried out to obtain the modified polyurethane;

[0010] Reaction principle:

[0011] In the preparation process of the modified polyurethane, first, hydroxyl-containing raw materials such as poly(tetrahydrofuran) glycol, hydroxy-terminated polysiloxane, and flame-retardant polyester are dissolved in N,N-dimethylformamide together with dibutyltin dilaurate catalyst. After heating to 80-100 °C, diphenylmethane diisocyanate is added. Under the action of the catalyst, the hydroxyl group attacks the isocyanate group in diphenylmethane diisocyanate as a nucleophile, and a nucleophilic addition reaction occurs to form a urethane bond, generating a terminal isocyanate group prepolymer. Subsequently, 3,3'-dichloro-4,4'-diaminodiphenylmethane is added. At 80-100 °C, its amino group reacts with the terminal isocyanate group of the prepolymer by virtue of strong nucleophilicity to form a urea bond, realizing the chain extension and growth of the molecular chain. Finally, a capping agent is added, and the single hydroxyl group in the capping agent reacts with the remaining -NCO to generate a stable urethane end group, terminating the chain growth, thereby obtaining the modified polyurethane.

[0012] The preparation method of the modified nylon is as follows: Hydrochloric acid dopamine and deionized water are added to a reaction kettle. After stirring until hydrochloric acid dopamine is completely dissolved, hexamethylenediamine and adipic acid are added to the reaction kettle, and sodium hydroxide solution is added dropwise thereto until the pH is neutral, and post-treatment is carried out to obtain the modified nylon.

[0013] Reaction principle:

[0014] First, hexamethylenediamine, adipic acid, and hydrochloric acid dopamine are dissolved in deionized water, and the temperature is raised to 80-90 °C. Hexamethylenediamine and adipic acid are neutralized to form nylon 66 salt, and hydrochloric acid dopamine dissociates into cations. Subsequently, sodium hydroxide is added dropwise to adjust the pH to neutral, so that dopamine returns to the free state. Then, under nitrogen protection, the temperature is raised to 120-150 °C, and nylon 66 salt is preliminarily polycondensed to form oligomers. At this time, dopamine is dispersed therein by physical mixing or a small amount of amidation reaction. Finally, the temperature is raised to 240-260 °C, the system melts, the nylon chain grows rapidly, and the amino group of dopamine reacts with the terminal carboxyl group of the nylon chain to undergo an amidation reaction and be covalently incorporated into the main chain. Its catechol structure may also be oxidized and crosslinked to form branches or networks, thereby obtaining the modified nylon.

[0015] Further, the dosage ratio of the polytetrahydrofuran ether glycol, hydroxyl-terminated polysiloxane, flame-retardant polyester, catalyst, N,N-dimethylformamide, chain extender, and end-capping agent is 100 mL: 10 - 20 g: 20 - 30 g: 1 - 2 mL: 300 mL: 3 - 5 g: 2 - 3 g. The addition amount of diphenylmethane diisocyanate is 0.55 times the total molar amount of oxygen-containing functional groups in the polytetrahydrofuran ether glycol, hydroxyl-terminated polysiloxane, and flame-retardant polyester. The catalyst is dibutyltin dilaurate, the chain extender is 3,3'-dichloro-4,4'-diaminodiphenylmethane, and the end-capping agent is glycidol.

[0016] Further, in the preparation of the modified nylon, the dosage ratio of hexamethylenediamine, adipic acid, dopamine hydrochloride, and deionized water is 10 g: 6 g: 1 g: 2 mL, and the concentration of the sodium hydroxide solution is 0.5 mol / L.

[0017] Further, the preparation method of the hydroxyl-terminated polysiloxane is as follows: Octamethylcyclotetrasiloxane, trifluoropropyltrimethylcyclotrisiloxane, and tetramethyltetravinylcyclotetrasiloxane are added to a reaction kettle. Under a nitrogen atmosphere at 90 °C, it is stirred for 30 min, then the temperature is raised to 110 °C, and tetramethylammonium hydroxide and the end-capping agent H2O are added, and the reaction continues for 3 h. After post-treatment, the hydroxyl-terminated polysiloxane is obtained. The dosage ratio of octamethylcyclotetrasiloxane, trifluoropropyltrimethylcyclotrisiloxane, tetramethyltetravinylcyclotetrasiloxane, tetramethylammonium hydroxide, and the end-capping agent H2O is 100 g: 50 g: 4 g: 0.01 g: 0.29 mL.

[0018] Reaction principle:

[0019] Under a nitrogen atmosphere, using tetramethylammonium hydroxide as a catalyst, octamethylcyclotetrasiloxane, trifluoropropyltrimethylcyclotrisiloxane, and tetramethyltetravinylcyclotetrasiloxane are added to a reaction kettle and premixed at 90 °C, then the temperature is raised to 110 °C, and ring-opening copolymerization occurs. The OH - ions attack the silicon atom of the cyclic siloxane, opening the Si - O bond to initiate polymerization. The three monomers randomly open the ring to form a linear polysiloxane chain containing methyl, trifluoropropyl, and vinyl side groups. Subsequently, the added end-capping agent H2O reacts with the silicon oxyanion at the chain end to generate a hydroxyl-terminated group, terminating the chain growth. Finally, after post-treatment to remove low-boiling substances and neutralize the catalyst, the hydroxyl-terminated polysiloxane is obtained.

[0020]

[0021] Further, the preparation method of the flame-retardant polyester is as follows: In a nitrogen atmosphere, phthalic anhydride, diphenyl phosphate, and ethylene glycol are added to a reaction kettle, and the temperature is raised to 120 - 140 °C. After holding the reaction for 1 - 2 h, the temperature is gradually raised to 180 - 220 °C, a catalyst is added, and the reaction is carried out for 3 - 5 h. Then, the system temperature is raised to 230 - 260 °C and maintained for 2 - 4 h to obtain the flame-retardant polyester.

[0022] Further, the molar ratio of phthalic anhydride, diphenyl phosphate, ethylene glycol, and the catalyst is 1:1.2:0.3, the catalyst is stannous octoate, and the dosage is 0.3% - 1.0% of the total monomer mass.

[0023] Further, the NH2-rGO / MoSe2 is prepared by the following steps:

[0024] A1. Graphene oxide is added to absolute ethanol and ultrasonically dispersed for 2 h. Deionized water, acetic acid, and a silane coupling agent are added to the reaction kettle, and the temperature is raised to 78 °C for reaction for 12 h to obtain NH2-rGO;

[0025] Reaction principle:

[0026] First, graphene oxide is ultrasonically dispersed in absolute ethanol. The polarity of ethanol and the mechanical action of ultrasound are used to break its agglomeration to form a stable suspension; subsequently, deionized water, acetic acid, and γ-aminopropyltriethoxysilane are added to the system. The acidic environment provided by acetic acid catalyzes the hydrolysis of the silane coupling agent, converting its ethoxy group into a silanol group; then, the silanol group undergoes a condensation reaction with the hydroxyl and carboxyl groups on the surface of graphene oxide, forming a silicon-oxygen bond through dehydration to graft the amino group onto the surface of graphene oxide; meanwhile, ethanol in the system exhibits weak reducibility under acidic conditions and at 78 °C, promoting the deoxygenation and reduction of graphene oxide to form NH2-rGO with both amino activity and reduction characteristics.

[0027] A2. NH2-rGO and Na2MoO4·2H2O are added to deionized water. After ultrasonic treatment for 30 min, a Se solution and hydrazine hydrate are added, and the mixture is stirred at 20 - 30 °C for 1 h. Then, the mixed solution is transferred to a hydrothermal reaction kettle lined with polytetrafluoroethylene and maintained at 200 °C for reaction for 24 h, and then post-treated to obtain NH2-rGO / MoSe2.

[0028] Reaction principle:

[0029] First, NH2-rGO and Na2MoO4·2H2O are ultrasonically dispersed in deionized water, and the protonated amino group on the surface of NH2-rGO adsorbs MoO4 2- , and then a Se solution and hydrazine hydrate are added. Hydrazine hydrate reduces Se to Se 2-Meanwhile, Mo(Ⅵ) was pre-reduced to Mo(Ⅳ); after transferring to a hydrothermal reactor and heating to 200 °C, Mo(Ⅳ) reacted with Se 2- to form layered MoSe2 nanosheets, and these nanosheets were uniformly grown on the surface of NH2-rGO through the anchoring effect of amino groups to obtain NH2-rGO / MoSe2.

[0030] Furthermore, in step A1, the dosage ratio of graphene oxide, absolute ethanol, deionized water, acetic acid and silane coupling agent was 0.25 g: 25 mL: 3 mL: 0.25 mL: 1 g, and the silane coupling agent was γ-aminopropyltriethoxysilane; in step A2, the dosage ratio of NH2-rGO, Na2MoO4·2H2O, deionized water and Se solution was 1 g: 3 g: 20 mL: 20 mL, and the Se solution was composed of Se and N2H4·H2O at a dosage ratio of 0.41 g: 15 mL.

[0031] The present invention also provides a preparation method of a highly wear-resistant polyurethane material for sieve plate processing: adding modified polyurethane into a mixer, melting the modified polyurethane at 90-110 °C, then adding NH2-rGO / MoSe2 and reacting for 15-20 min, and finally adding modified nylon and auxiliary additives, heating to 250-260 °C and reacting for 10-20 min to discharge, obtaining the polyurethane material.

[0032] The present invention has the following beneficial effects:

[0033] 1. In the present invention, first, hydroxyl-terminated polysiloxane significantly improves the molecular chain flexibility of polyurethane by introducing silicon-oxygen bonds and fluoroalkyl side chains. The low glass transition temperature of the silicon-oxygen bond endows the material with excellent low-temperature toughness, while the strong hydrophobicity and low surface energy of the trifluoropropyl group effectively reduce the friction between molecular chains, increasing the elongation at break of polyurethane. Secondly, after blending hydroxyl-terminated polysiloxane with polytetrahydrofuran ether glycol, a "rigid-flexible block" network structure is formed through cross-linking by isocyanate groups, improving the hardness, tensile strength and tear strength of the material. Finally, the flame-retardant polyester endows the material with flame-retardant properties through the phosphorus-nitrogen synergistic flame-retardant mechanism while improving the mechanical properties. The phosphate groups in the molecular chain decompose to form phosphoric acid and metaphosphoric acid during combustion, promoting the formation of a carbon layer and inhibiting the release of combustible gases, while the phthalic anhydride skeleton enhances the compactness of the carbon layer, improving the vertical burning grade and limiting oxygen index of the polyurethane material, and at the same time increasing the tensile strength and tear strength of the material, enabling the material to withstand the high-frequency vibration load of the sieve plate and meet the fire safety requirements of industrial scenarios.

[0034] 2. The two-dimensional sheet structure of the amino-reduced graphene oxide (NH2-rGO) of the present invention is tightly combined with the polyurethane chain segment through hydrogen bonds to form a nano-scale reinforcing filler. The amino groups on its surface react with the isocyanate groups of the polyurethane to form urea bonds, effectively inhibiting filler agglomeration and interfacial debonding, reducing the plastic deformation of the matrix. The MoSe2 nanosheets are embedded between the rGO sheets as "molecular bearings", using the layer-sliding characteristics to reduce the friction coefficient and lower the interfacial energy loss. At the same time, the Se atoms form strong interactions with the π-electron conjugate system of rGO, preventing the nanosheets from falling off during the wear process. In addition, the conjugated structure of NH2-rGO / MoSe2 can also improve the thermal conductivity of the material, quickly dissipate the heat generated by friction, avoid material softening caused by local overheating, and further extend the service life of the sieve plate.

[0035] 3. In the present invention, the amino groups of dopamine react with the isocyanate groups of the polyurethane to form urea bonds, and the catechol structure oxidizes and self-polymerizes to form a polydopamine cross-linked network, covalently anchoring the nylon chain segment and the polyurethane molecular chain, so that the interfacial shear strength of the composite material is improved. This strong interfacial interaction is directly reflected in the tensile strength and tear strength. In addition, the nitrogen element in the modified nylon and the phosphorus element of the flame-retardant polyester form a "nitrogen-phosphorus synergistic" mechanism. During combustion, the nitrogen element promotes carbon formation and inhibits the release of combustible gases, and the phosphorus element enhances the stability of the carbon layer, making the vertical burning grade of the material stably reach V0 level, significantly improving the flame-retardant performance of the material. Detailed implementation mode

[0036] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0037] In the present invention, the polytetrahydrofuran ether glycol is selected from Jining Sun Never Sets Biotechnology Co., Ltd., with a CAS number of 25190-06-1, a product molecular weight of 2000 ± 50, an active ingredient content of ≥ 99.5%, a model of PTMG, and a product number of J30633;

[0038] In the present invention, the dibutyltin dilaurate is selected from Shandong Qiyuan Chemical Co., Ltd., with a CAS number of 77-58-7, an active ingredient content of 18%, and a flash point of 226.7 °C;

[0039] In the present invention, the graphene oxide is selected from Shanghai Xiangtian Nanos Materials Co., Ltd., with a specification of Go-01, an active ingredient content of 99.9%, a product number of Go, and a model of XT-Go.

[0040] Example 1

[0041] This embodiment provides a preparation method of a highly wear-resistant polyurethane material for sieve plate processing, including the following steps:

[0042] S1. Prepare hydroxy-terminated polysiloxane

[0043] Weigh: 100 g of octamethylcyclotetrasiloxane, 50 g of trifluoropropyltrimethylcyclotrisiloxane and 4 g of tetramethyltetravinylcyclotetrasiloxane and add them to a reaction kettle. Under a nitrogen atmosphere at 90 °C, stir for 30 min, then continue to heat up to 110 °C, add 0.01 g of tetramethylammonium hydroxide and 0.29 mL of capping agent H2O, and continue to react for 3 h. After the reaction is completed, the temperature of the reaction kettle is reduced to room temperature. Add 50 mL of deionized water to the reaction kettle, stir and disperse for 20 min, and let it stand. The upper layer liquid is washed 3 times with deionized water and then transferred to a rotary evaporator with a water bath temperature of 80 °C to distill off low-boiling substances under reduced pressure to obtain hydroxy-terminated polysiloxane.

[0044] S2. Prepare flame-retardant polyester

[0045] Weigh: 5 g of phthalic anhydride, 2 g of diphenyl phosphate and 3 g of ethylene glycol and add them to a reaction kettle. In a nitrogen atmosphere, heat up to 120 °C, keep the temperature for 1 h, then gradually heat up to 180 °C, add 0.1 g of stannous octoate as a catalyst, react for 3 h, then raise the system temperature to 230 °C and maintain it for 2 h. After discharging while it is hot, cool and solidify, and crush to obtain flame-retardant polyester.

[0046] S3. Prepare modified polyurethane

[0047] Weigh: 100 mL of polytetrahydrofuran glycol, 10 g of hydroxy-terminated polysiloxane, 20 g of flame-retardant polyester and 1 mL of dibutyltin dilaurate and add them to a reaction kettle containing 300 mL of N,N-dimethylformamide and stir. After heating up to 80 °C, calculate the addition amount of diphenylmethane diisocyanate according to 0.55 times the total molar amount of oxygen-containing functional groups in polytetrahydrofuran glycol, hydroxy-terminated polysiloxane and flame-retardant polyester, and add it to the reaction kettle. After keeping the temperature for 2 h, add 3 g of 3,3'-dichloro-4,4'-diaminodiphenylmethane to it. Add 2 g of capping agent glycidyl ether to the reaction kettle, keep the temperature for 40 min, and reduce the temperature of the reaction kettle to room temperature. Add 1500 mL of deionized water to the reaction kettle, stir and disperse for 30 min, filter by suction. The filter cake is washed 3 times with purified water and then dried by suction. The filter cake is then transferred to a drying oven at 70 °C and dried to constant weight to obtain modified polyurethane.

[0048] S4. Prepare NH2-rGO / MoSe2

[0049] Weigh: Add 0.25 g of graphene oxide to 25 mL of absolute ethanol, ultrasonically disperse for 2 h, add 3 mL of deionized water, 0.25 mL of acetic acid and 1 g of γ-aminopropyltriethoxysilane to the reaction kettle, heat up to 78 °C and react for 12 h. After the reaction is completed, cool the temperature of the reaction kettle to room temperature, wash the product once with ethanol, then wash it 3 times with deionized water, and finally transfer it to a vacuum drying oven and dry it at 60 °C for 12 h to obtain NH2-rGO;

[0050] Mix Se and N2H4·H2O evenly according to the dosage ratio of 0.41 g : 15 mL to obtain a Se solution for standby;

[0051] Weigh: Add 1 g of NH2-rGO and 3 g of Na2MoO4·2H2O to 20 mL of deionized water, ultrasonically treat for 30 min, then add 20 mL of the Se solution, stir at 20 °C for 1 h, and then transfer the mixed solution to a hydrothermal reaction kettle lined with polytetrafluoroethylene. After maintaining the reaction at 200 °C for 24 h, cool to room temperature after the reaction is completed, transfer to a vacuum drying oven, and dry at 60 °C for 12 h to obtain NH2-rGO / MoSe2.

[0052] S5. Preparation of modified nylon

[0053] Weigh: Add 1 g of dopamine hydrochloride and 2 mL of deionized water to a reaction kettle under nitrogen protection, heat the reaction kettle to 80 °C, stir until dopamine hydrochloride is completely dissolved, add 10 g of hexamethylenediamine and 6 g of adipic acid to the reaction kettle, stir for 20 min, add 0.5 mol / L sodium hydroxide solution dropwise to the reaction kettle until the pH is neutral. After the reaction kettle is sealed, heat the heat exchange medium of the reaction kettle to 120 °C and keep it warm for 0.5 h. Then heat the heat exchange medium of the reaction kettle to 240 °C and keep it warm for 3 h. After the reaction is completed, discharge the material while it is hot. Wait for the reactant to cool to room temperature, crush it, wash the product 3 times with deionized water, transfer it to a vacuum drying oven, and dry it at 80 °C for 12 h to obtain modified nylon.

[0054] S6. Preparation of polyurethane material

[0055] The auxiliary additive consists of 8 parts of curing agent, 1 part of antioxidant and 3 parts of plasticizer;

[0056] Weigh by weight: Add 80 parts of modified polyurethane to a mixer, melt the modified polyurethane at 90 - 110 °C, then add 3 parts of NH2-rGO / MoSe2 and react for 15 min. Finally, add 10 parts of modified nylon and 2 parts of auxiliary additive, heat up to 240 °C and react for 10 min, then discharge the material to obtain the polyurethane material.

[0057] Example 2

[0058] This embodiment provides a preparation method of a highly wear-resistant polyurethane material for sieve plate processing, including the following steps:

[0059] S1. Prepare hydroxy-terminated polysiloxane

[0060] Weigh: 100 g of octamethylcyclotetrasiloxane, 50 g of trifluoropropyltrimethylcyclotrisiloxane, and 4 g of tetramethyltetravinylcyclotetrasiloxane and add them to a reaction kettle. Under a nitrogen atmosphere at 90 °C, stir for 30 min, then continue to heat up to 110 °C, add 0.01 g of tetramethylammonium hydroxide and 0.29 mL of capping agent H2O, and continue to react for 3 h. After the reaction is completed, lower the temperature of the reaction kettle to room temperature, add 50 mL of deionized water to the reaction kettle, stir and disperse for 25 min, let it stand, wash the upper layer liquid with deionized water 3 times and then transfer it to a rotary evaporator with a water bath temperature of 85 °C to distill off the low-boiling substances under reduced pressure to obtain hydroxy-terminated polysiloxane.

[0061] S2. Prepare flame-retardant polyester

[0062] Weigh: 5 g of phthalic anhydride, 2 g of diphenyl phosphate, and 3 g of ethylene glycol and add them to a reaction kettle. In a nitrogen atmosphere, heat up to 120 °C, keep the temperature for 1 h of reaction, then gradually heat up to 180 °C, add 0.1 g of stannous octoate as a catalyst, react for 3 h, then raise the temperature of the system to 230 °C and maintain it for 2 h. After discharging while it is hot, cool and solidify, and crush to obtain flame-retardant polyester.

[0063] S3. Prepare modified polyurethane

[0064] Weigh: 100 mL of polytetrahydrofuran glycol, 15 g of hydroxy-terminated polysiloxane, 25 g of flame-retardant polyester, and 1.5 mL of dibutyltin dilaurate and add them to a reaction kettle containing 300 mL of N,N-dimethylformamide and stir. After heating up to 90 °C, calculate the addition amount of diphenylmethane diisocyanate according to 0.55 times the total molar amount of oxygen-containing functional groups in polytetrahydrofuran glycol, hydroxy-terminated polysiloxane, and flame-retardant polyester, and add it to the reaction kettle. After keeping the temperature for 2.5 h of reaction, then add 4 g of 3,3'-dichloro-4,4'-diaminodiphenylmethane to it. Add 2.5 g of capping agent glycidyl ether to the reaction kettle, keep the temperature for 50 min of reaction, lower the temperature of the reaction kettle to room temperature, add 1500 mL of deionized water to the reaction kettle, stir and disperse for 40 min, filter by suction, wash the filter cake with purified water 3 times and then drain it. Transfer the filter cake to a drying oven at 75 °C and dry it to constant weight to obtain modified polyurethane.

[0065] S4. Prepare NH2-rGO / MoSe2

[0066] Weigh: 0.25 g of graphene oxide was added to 25 mL of absolute ethanol, and ultrasonically dispersed for 2 h. 3 mL of deionized water, 0.25 mL of acetic acid and 1 g of γ-aminopropyltriethoxysilane were added to the reaction kettle, and the temperature was raised to 78 °C for reaction for 12 h. After the reaction was completed, the temperature of the reaction kettle was lowered to room temperature. The product was washed once with ethanol and then washed three times with deionized water. Finally, it was transferred to a vacuum drying oven and dried at 60 °C for 12 h to obtain NH2-rGO;

[0067] Se and N2H4·H2O were mixed evenly according to the dosage ratio of 0.41 g : 15 mL to obtain a Se solution for standby;

[0068] Weigh: 1 g of NH2-rGO and 3 g of Na2MoO4·2H2O were added to 20 mL of deionized water. After ultrasonic treatment for 30 min, 20 mL of the Se solution was added, and the mixture was stirred at 25 °C for 1 h. Then the mixed solution was transferred to a hydrothermal reaction kettle lined with polytetrafluoroethylene and maintained at 200 °C for reaction for 24 h. After the reaction was completed, it was cooled to room temperature, transferred to a vacuum drying oven and dried at 60 °C for 12 h to obtain NH2-rGO / MoSe2.

[0069] S5. Preparation of modified nylon

[0070] Weigh: 1 g of dopamine hydrochloride and 2 mL of deionized water were added to a reaction kettle under nitrogen protection. The temperature of the reaction kettle was raised to 85 °C and stirred until dopamine hydrochloride was completely dissolved. 10 g of hexamethylenediamine and 6 g of adipic acid were added to the reaction kettle and stirred for 25 min. 0.5 mol / L sodium hydroxide solution was added dropwise to the reaction kettle until the pH was neutral. After the reaction kettle was sealed, the heat exchange medium of the reaction kettle was heated to 140 °C and kept warm for reaction for 0.5 h. Then the heat exchange medium of the reaction kettle was heated to 250 °C and kept warm for reaction for 4 h. After the reaction was completed, the product was discharged while it was hot. After the reactant was cooled to room temperature, it was crushed, washed three times with deionized water, transferred to a vacuum drying oven and dried at 80 °C for 12 h to obtain modified nylon.

[0071] S6. Preparation of polyurethane material

[0072] The auxiliary additive consists of 10 parts of curing agent, 1 part of antioxidant and 4 parts of plasticizer;

[0073] Weigh by weight: 90 parts of modified polyurethane were added to a kneader, and the modified polyurethane was melted at 100 °C. Then 4 parts of NH2-rGO / MoSe2 were added and reacted for 17 min. Finally, 12 parts of modified nylon and 2 parts of auxiliary additive were added, and the temperature was raised to 250 °C and reacted for 15 min, and then discharged to obtain a polyurethane material.

[0074] Example 3

[0075] This embodiment provides a preparation method of a highly wear-resistant polyurethane material for sieve plate processing, including the following steps:

[0076] S1. Prepare hydroxyl-terminated polysiloxane

[0077] Weigh: 100 g of octamethylcyclotetrasiloxane, 50 g of trifluoropropyltrimethylcyclotrisiloxane and 4 g of tetramethyltetravinylcyclotetrasiloxane and add them to a reaction kettle. Under a nitrogen atmosphere at 90 °C, stir for 30 min, then continue to heat up to 110 °C, add 0.01 g of tetramethylammonium hydroxide and 0.29 mL of capping agent H2O, and continue to react for 3 h. After the reaction is completed, the temperature of the reaction kettle is reduced to room temperature. Add 50 mL of deionized water to the reaction kettle, stir and disperse for 30 min, then let it stand. The upper layer liquid is washed 3 times with deionized water and then transferred to a rotary evaporator with a water bath temperature of 90 °C to distill off the low-boiling substances under reduced pressure to obtain hydroxyl-terminated polysiloxane.

[0078] S2. Prepare flame-retardant polyester

[0079] Weigh: 5 g of phthalic anhydride, 2 g of diphenyl phosphate and 3 g of ethylene glycol and add them to a reaction kettle. In a nitrogen atmosphere, heat up to 120 °C, keep the temperature for 1 h of reaction, then gradually heat up to 180 °C, add 0.1 g of stannous octoate as a catalyst, react for 3 h, then raise the system temperature to 230 °C and maintain it for 2 h. After discharging while it is hot, cool and solidify, and then crush to obtain flame-retardant polyester.

[0080] S3. Prepare modified polyurethane

[0081] Weigh: 100 mL of polytetrahydrofuran ether glycol, 20 g of hydroxyl-terminated polysiloxane, 30 g of flame-retardant polyester and 2 mL of dibutyltin dilaurate and add them to a reaction kettle containing 300 mL of N,N-dimethylformamide and stir. After heating up to 100 °C, calculate the addition amount of diphenylmethane diisocyanate according to 0.55 times the total molar amount of oxygen-containing functional groups in polytetrahydrofuran ether glycol, hydroxyl-terminated polysiloxane and flame-retardant polyester, and add it to the reaction kettle. After keeping the temperature for 3 h of reaction, then add 5 g of 3,3'-dichloro-4,4'-diaminodiphenylmethane to it. Add 3 g of capping agent glycidyl ether to the reaction kettle, keep the temperature for 60 min of reaction, and reduce the temperature of the reaction kettle to room temperature. Add 1500 mL of deionized water to the reaction kettle, stir and disperse for 50 min, then filter. The filter cake is washed 3 times with purified water and then dried by suction. The filter cake is then transferred to a drying oven at 80 °C and dried to constant weight to obtain modified polyurethane.

[0082] S4. Prepare NH2-rGO / MoSe2

[0083] Weigh: Add 0.25 g of graphene oxide to 25 mL of absolute ethanol, ultrasonically disperse for 2 h, add 3 mL of deionized water, 0.25 mL of acetic acid and 1 g of γ-aminopropyltriethoxysilane to the reaction kettle, heat up to 78 °C and react for 12 h. After the reaction is completed, cool the temperature of the reaction kettle to room temperature. Wash the product once with ethanol, then wash it 3 times with deionized water, and finally transfer it to a vacuum drying oven and dry at 60 °C for 12 h to obtain NH2-rGO;

[0084] Mix Se and N2H4·H2O evenly according to the dosage ratio of 0.41 g : 15 mL to obtain a Se solution for standby;

[0085] Weigh: Add 1 g of NH2-rGO and 3 g of Na2MoO4·2H2O to 20 mL of deionized water. After ultrasonication for 30 min, add 20 mL of the Se solution, stir at 30 °C for 1 h, then transfer the mixed solution to a hydrothermal reaction kettle lined with polytetrafluoroethylene, maintain the reaction at 200 °C for 24 h, cool to room temperature after the reaction is over, transfer to a vacuum drying oven and dry at 60 °C for 12 h to obtain NH2-rGO / MoSe2.

[0086] S5. Preparation of modified nylon

[0087] Weigh: Add 1 g of dopamine hydrochloride and 2 mL of deionized water to a reaction kettle under nitrogen protection. Heat the reaction kettle to 90 °C and stir until dopamine hydrochloride is completely dissolved. Add 10 g of hexamethylenediamine and 6 g of adipic acid to the reaction kettle, stir for 30 min, add 0.5 mol / L sodium hydroxide solution dropwise to the reaction kettle until the pH is neutral. After the reaction kettle is sealed, heat the heat exchange medium of the reaction kettle to 150 °C and keep the reaction for 1 h. Then heat the heat exchange medium of the reaction kettle to 260 °C and keep the reaction for 5 h. After the reaction is over, discharge the material while it is hot. Wait for the reactant to cool to room temperature, crush it, wash the product 3 times with deionized water, transfer to a vacuum drying oven and dry at 80 °C for 12 h to obtain modified nylon.

[0088] S6. Preparation of polyurethane material

[0089] The auxiliary additive consists of 12 parts of curing agent, 2 parts of antioxidant and 5 parts of plasticizer;

[0090] Weigh by weight: Add 100 parts of modified polyurethane to a mixer, melt the modified polyurethane at 110 °C, then add 5 parts of NH2-rGO / MoSe2 and react for 20 min. Finally, add 15 parts of modified nylon and 3 parts of auxiliary additive, heat up to 260 °C and react for 20 min, then discharge the material to obtain a polyurethane material.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 3 is that in step S1, trifluoropropyltrimethylcyclotrisiloxane was not added.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 3 is that step S2 was cancelled, and flame-retardant polyester was not added in S3.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 3 is that step S4 was cancelled, and graphene oxide was used to replace NH2-rGO / MoSe2 in step S6.

[0097] Comparative Example 4

[0098] The difference between this comparative example and Example 3 is that in step S5, dopamine hydrochloride was not added.

[0099] Performance test:

[0100] With reference to the standard GB / T 33091-2016 "Polyurethane Sieve Plate", the hardness, tensile strength, tear strength, and relative volume wear of a highly wear-resistant polyurethane material for sieve plate processing prepared in Examples 1-3 and Comparative Examples 1-4 were measured;

[0101] With reference to the standard T / SHPTA 015-2021 "Flame-Retardant Thermoplastic Polyurethane Elastomer Cable Material", the vertical burning grade of a highly wear-resistant polyurethane material for sieve plate processing prepared in Examples 1-3 and Comparative Examples 1-4 was measured. The specific test results are shown in Table 1 below:

[0102] Table 1 - Performance Detection Data Table of Samples

[0103]

[0104] Data analysis:

[0105] By comparing and analyzing the data in Table 1 above, for a highly wear-resistant polyurethane material for sieve plate processing prepared by the present invention, its measured hardness is 95.7 Shore A, tensile strength is 52.3 MPa, tear strength is 95.8 MPa, and relative volume wear is 8.4 mm 3 , and the vertical burning grade is V0;

[0106] Compared with Example 3, in Comparative Examples 1-2, hydroxyl-terminated polysiloxane forms a "rigid-flexible block" network structure through cross-linking with isocyanate groups after blending with polytetrahydrofuran ether glycol by introducing silicon-oxygen bonds and trifluoropropyl side chains, improving the material hardness to 95.7 Shore A, tensile strength to 52.3 MPa, and tear strength to 95.8 MPa. At the same time, through the phosphorus-nitrogen synergistic flame-retardant mechanism, the flame-retardant polyester improves the vertical burning grade from V2 to V0;

[0107] Compared with Example 3, in the NH2-rGO / MoSe2 nanohybrid filler of Comparative Example 3, the two-dimensional sheets of NH2-rGO are combined with polyurethane segments through hydrogen bonds to form urea bonds to inhibit agglomeration. The MoSe2 nanosheets act as "molecular bearings" to reduce the friction coefficient to 0.21, making the relative volume wear loss as low as 8.4 mm³, which is more than 40% lower than that of traditional polyurethane. Moreover, the conjugated structure improves the thermal conductivity to avoid local overheating;

[0108] Compared with Example 3, in Comparative Example 4, the modified nylon reacts with the polyurethane isocyanate group through the amino group of dopamine to form urea bonds, and the catechol structure oxidizes and self-polymerizes to form a crosslinked network, increasing the tensile strength and tear strength to 52.3 MPa and 95.8 MPa. At the same time, the nitrogen element and the phosphorus element of the flame-retardant polyester form a "nitrogen-phosphorus synergistic effect" to ensure that the vertical burning rating stably reaches V0 level.

[0109] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A highly wear-resistant polyurethane material for sieve plate processing, characterized in that, It comprises the following components by weight parts: 80 - 100 parts of modified polyurethane, 3 - 5 parts of NH2-rGO / MoSe2, 10 - 15 parts of modified nylon, and 2 - 3 parts of auxiliary additives; The auxiliary additives comprise the following components by weight parts: 8 - 12 parts of curing agent, 1 - 2 parts of antioxidant, and 3 - 5 parts of plasticizer; The preparation method of the modified polyurethane is as follows: Poly(tetramethylene ether) glycol, hydroxyl-terminated polysiloxane, flame-retardant polyester, and a catalyst are added to a reaction kettle containing N,N-dimethylformamide and stirred and mixed. Then, diphenylmethane diisocyanate and a chain extender are added thereto. After the reaction ends, a capping agent is finally added, and post-treatment is carried out to obtain the modified polyurethane; The preparation method of the modified nylon is as follows: Dopamine hydrochloride and deionized water are added to a reaction kettle. After stirring until dopamine hydrochloride is completely dissolved, hexamethylenediamine and adipic acid are added to the reaction kettle, and a sodium hydroxide solution is added dropwise thereto until the pH is neutral, and post-treatment is carried out to obtain the modified nylon.

2. The high-wear-resistant polyurethane material for sieve plate processing according to claim 1, wherein, The dosage ratio of the poly(tetramethylene ether) glycol, hydroxyl-terminated polysiloxane, flame-retardant polyester, catalyst, N,N-dimethylformamide, chain extender, and capping agent is 100 mL: 10 - 20 g: 20 - 30 g: 1 - 2 mL: 300 mL: 3 - 5 g: 2 - 3 g. The addition amount of the diphenylmethane diisocyanate is 0.55 times the total molar amount of oxygen-containing functional groups in the poly(tetramethylene ether) glycol, hydroxyl-terminated polysiloxane, and flame-retardant polyester. The catalyst is dibutyltin dilaurate, the chain extender is 3,3'-dichloro-4,4'-diaminodiphenylmethane, and the capping agent is glycidol.

3. A highly wear-resistant polyurethane material for sieve plate processing according to claim 1, characterized in that, In the preparation of the modified nylon, the dosage ratio of the hexamethylenediamine, adipic acid, dopamine hydrochloride, and deionized water is 10 g: 6 g: 1 g: 2 mL, and the concentration of the sodium hydroxide solution is 0.5 mol / L.

4. A highly wear-resistant polyurethane material for sieve plate processing according to claim 1, characterized in that, The preparation method of the hydroxyl-terminated polysiloxane is as follows: Octamethylcyclotetrasiloxane, trifluoropropyltrimethylcyclotrisiloxane, and tetramethyltetravinylcyclotetrasiloxane are added to a reaction kettle. Under a nitrogen atmosphere at 90 °C, it is stirred for 30 min, and the temperature is continuously raised to 110 °C. Tetramethylammonium hydroxide and a capping agent H2O are added, and the reaction continues for 3 h. Post-treatment is carried out to obtain the hydroxyl-terminated polysiloxane. The dosage ratio of the octamethylcyclotetrasiloxane, trifluoropropyltrimethylcyclotrisiloxane, tetramethyltetravinylcyclotetrasiloxane, tetramethylammonium hydroxide, and capping agent H2O is 100 g: 50 g: 4 g: 0.01 g: 0.29 mL.

5. A highly wear-resistant polyurethane material for sieve plate processing according to claim 1, characterized in that, The preparation method of the flame-retardant polyester is as follows: Under a nitrogen atmosphere, phthalic anhydride, diphenyl phosphate, and ethylene glycol are added to a reaction kettle. The temperature is raised to 120 - 140 °C, and after holding the temperature for reaction for 1 - 2 h, the temperature is gradually raised to 180 - 220 °C, a catalyst is added, and the reaction is carried out for 3 - 5 h. Then, the system temperature is raised to 230 - 260 °C and maintained for 2 - 4 h to obtain the flame-retardant polyester.

6. A highly wear-resistant polyurethane material for sieve plate processing according to claim 5, characterized in that, The mass ratio of the phthalic anhydride, diphenyl phosphate, ethylene glycol, and catalyst is 5: 2: 3: 0.1, and the catalyst is stannous octoate.

7. A highly wear-resistant polyurethane material for sieve plate processing according to claim 1, characterized in that, The NH2-rGO / MoSe2 is prepared by the following steps: A1. Add graphene oxide to absolute ethanol and ultrasonically disperse it for 2 h. Add deionized water, acetic acid, and silane coupling agent to the reaction kettle, heat up to 78 °C and react for 12 h to obtain NH2-rGO; A2. Add NH2-rGO and Na2MoO4·2H2O to deionized water. After ultrasonication for 30 min, add Se solution and stir at 20 - 30 °C for 1 h. Then transfer the mixed solution to a hydrothermal reaction kettle lined with polytetrafluoroethylene, maintain the reaction at 200 °C for 24 h, and perform post-treatment to obtain NH2-rGO / MoSe2.

8. A highly wear-resistant polyurethane material for sieve plate processing according to claim 7, characterized in that, In step A1, the dosage ratio of the graphene oxide, absolute ethanol, deionized water, acetic acid, and silane coupling agent is 0.25 g: 25 mL: 3 mL: 0.25 mL: 1 g, and the silane coupling agent is γ-aminopropyltriethoxysilane; in step A2, the dosage ratio of the NH2-rGO, Na2MoO4·2H2O, deionized water, and Se solution is 1 g: 3 g: 20 mL: 20 mL, and the Se solution is obtained by mixing Se and N2H4·H2O evenly according to the dosage ratio of 0.41 g: 15 mL.

9. A highly wear-resistant polyurethane material for sieve plate processing according to any one of claims 1-8, characterized in that, The preparation method of the highly wear-resistant polyurethane material for sieve plate processing is as follows: Add modified polyurethane to a mixer, melt the modified polyurethane at 90 - 110 °C, then add NH2-rGO / MoSe2 and react for 15 - 20 min. Finally, add modified nylon and auxiliary additives, heat up to 240 - 260 °C and react for 10 - 20 min, and discharge to obtain the polyurethane material.

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