Impact-resistant anti-clogging polyurethane sieve plate and preparation method thereof

Abstract

The application discloses an anti-impact and anti-hole-blocking polyurethane sieve plate and a preparation method thereof, and belongs to the technical field of polyurethane sieve plate preparation, and is used for solving the technical problem that the anti-impact performance and anti-hole-blocking performance of the polyurethane sieve plate in the prior art need to be further improved, and specifically comprises the following steps: stirring polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane in a reaction kettle protected by a nitrogen atmosphere, heating the reaction kettle to 55-65 DEG C, adding isophorone diisocyanate and dibutyltin dilaurate, heating the reaction kettle to 75-85 DEG C, and keeping stirring for 3-4 h to obtain an isocyanate-terminated prepolymer A component. In the application, the isocyanate-terminated prepolymer A component is first synthesized, then is blended with a coordination curing agent B component, and is poured and cast, and is subjected to stepwise heating, curing and cross-linking to construct the polyurethane sieve plate, so that the anti-impact performance of the polyurethane sieve plate is improved, and the anti-hole-blocking capacity of the polyurethane sieve plate is also improved.

Description

Technical Field

[0001] This invention relates to the field of polyurethane sieve plate preparation technology, specifically to an impact-resistant and anti-clogging polyurethane sieve plate and its preparation method. Background Technology

[0002] Polyurethane screens, due to their combination of wear resistance and elasticity, have gradually replaced some metal screens and are being developed for high-impact and high-viscosity working conditions. Current research has shifted from simply improving wear resistance to synergistic optimization of impact resistance, fatigue resistance, and pore clogging prevention. The focus is on improving the structural stability after repeated impacts from ore during screening and the continuous screening capacity under the action of wet and sticky particles.

[0003] When preparing polyurethane sieve plates, polyether-type or polyester-type polyurethane is often used as the matrix. Modification is achieved by increasing the hard segment content, filling with carbon black or inorganic nanoparticles, and grafting acrylic monomers. Although this can improve local performance to some extent, it is still difficult to balance impact resistance, anti-adhesion and long-term dimensional stability. Under complex working conditions, problems such as pore blockage and cracking are prone to occur simultaneously.

[0004] Currently, traditional polyurethanes mostly rely on fixed covalent cross-linked structures to bear external forces. When subjected to high-frequency impacts and cyclic loads, the internal stress is difficult to transfer and dissipate in time, which easily leads to stress concentration in local areas and induces crack propagation. In addition, conventional low surface energy anti-sticking components are mostly present in the form of physical admixtures, with limited bonding with the matrix. They are prone to migration or failure under long-term wear and vibration conditions. Furthermore, improving toughness by increasing the content of flexible chains often weakens the network strength, resulting in creep deformation of the sieve plate and a decrease in sieve hole stability under heavy load conditions.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an impact-resistant and anti-clogging polyurethane sieve plate and its preparation method, which solves the technical problem that the impact resistance and anti-clogging performance of polyurethane sieve plates in the prior art need to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: a method for preparing an impact-resistant and anti-clogging polyurethane sieve plate, comprising the following steps:

[0008] Step 1: Place polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane in a nitrogen-protected reactor and stir. Heat the reactor to 55-65°C, add isophorone diisocyanate and dibutyltin dilaurate, heat the reactor to 75-85°C, and stir for 3-4 hours to obtain isocyanate-terminated prepolymer component A.

[0009] Step 2: Dimethylglyoxime, 1,4-butanediol, 2,6-pyridinediethanol, sorbitan monooleate, fluorinated pyridine hyperbranched modifier and excipients are placed in a reaction vessel and stirred. Zinc chloride tetrahydrofuran solution is added. The reaction vessel is heated to 35-45℃ and kept at this temperature for 2-4 hours. The solvent is removed under reduced pressure, and the mixture is allowed to stand to remove bubbles, thus obtaining component B of the coordination curing agent.

[0010] Step 3: Place the terminal isocyanate prepolymer component A in a reactor and stir. Heat the reactor to 65-75℃, add the coordination curing agent component B preheated to 45-55℃, stir evenly, and pour into a sieve plate mold preheated to 75-80℃. Keep the mold at 75-85℃ for 1.5-2 hours. The polyurethane sieve plate is obtained by step heat treatment.

[0011] Furthermore, in step one, the weight ratio of the polytetrahydrofuran, hydroxyl-terminated polydimethylsiloxane, and dibutyltin dilaurate is 10-12:0.5-1:0.01-0.02, the molar amount of isophorone diisocyanate is 0.55 times the total molar amount of hydroxyl groups in the polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane, and the number-average molecular weight of the polytetrahydrofuran is 1000-2000.

[0012] Furthermore, in step two, the ratio of the amounts of dimethylglyoxime, 1,4-butanediol, 2,6-pyridinediethanol, sorbitan monooleate, fluorinated pyridine hyperbranching modifier, excipients, and zinc chloride tetrahydrofuran solution is 8-10g:6-8g:1-3g:4-6g:1-2g:0.5-1g:5-7mL, and the concentration of the zinc chloride tetrahydrofuran solution is 20-30wt%.

[0013] Furthermore, in step two, the excipients are composed of antioxidant 1010, ultraviolet absorber UV-326, N,N'-2,2',6,6'-tetraisopropylphenylcarbodiimide and polyvinyl isobutyl ether in a mass ratio of 2-4:1-3:2-3:0.5-1.

[0014] Furthermore, in step three, the weight ratio of the terminal isocyanate prepolymer component A to the coordination curing agent component B is 10-12:1-2. The stepped heat treatment step includes: transferring the sieve plate mold to a vacuum drying oven at a temperature of 90-100℃ and keeping it at that temperature for 3-5 hours, then raising the temperature of the vacuum drying oven to 115-125℃ and keeping it at that temperature for 6-8 hours, and then naturally cooling it to room temperature to obtain a polyurethane sieve plate.

[0015] Furthermore, the fluorinated terminal pyridine hyperbranched modifier is prepared by the following steps:

[0016] A1. Trimethylolpropane triacrylate, diethanolamine and methanol were placed in a reaction vessel under nitrogen atmosphere and stirred. The reaction vessel was heated to 50-60℃ and kept at the temperature for 20-24h. The end-hydroxyl hyperbranched intermediate was obtained by post-treatment.

[0017] A2. Place the hydroxyl-terminated hyperbranched intermediate, toluene, and N,N-dimethylformamide in a reaction vessel and stir. Add p-toluenesulfonic acid and nicotinic acid. Heat the reaction vessel to 110-120℃ and maintain the temperature for 4-6 hours. Add perfluorohexanoic acid and maintain the temperature for 3-5 hours. Post-treatment yields a fluorinated pyridine-terminated hyperbranched modifier.

[0018] Further, in step A1, the ratio of trimethylolpropane triacrylate, diethanolamine, and methanol is 2-4g:3-6g:80-100mL. The post-processing step includes: after the reaction is completed, wait for the reaction to cool to room temperature, transfer the reaction solution to a rotary evaporator at a temperature of 40-50℃, remove the solvent by rotary evaporation under reduced pressure, and obtain the terminal hydroxyl hyperbranched intermediate.

[0019] Further, in step A2, the ratio of the terminal hydroxyl hyperbranched intermediate, toluene, N,N-dimethylformamide, p-toluenesulfonic acid, nicotinic acid, and perfluorohexanoic acid is 5-7g:25-35mL:15-20mL:0.1-0.2g:2-4g:6-8g. The post-processing steps include: after the reaction is completed, wait for the reaction system to cool to room temperature, drop the reaction solution into diethyl ether to precipitate, filter, wash the filter cake with diethyl ether 2-4 times, transfer it to an oven at 30-40℃, and dry it to constant weight to obtain a fluorinated terminal pyridine hyperbranched modifier.

[0020] The present invention also proposes an impact-resistant and anti-clogging polyurethane sieve plate, which is prepared by the above-mentioned preparation method of an impact-resistant and anti-clogging polyurethane sieve plate.

[0021] The present invention has the following beneficial effects:

[0022] 1. This invention constructs a dual energy absorption system of covalent and sacrificial bonds by using main chain siloxane blocks and zinc-nitrogen coordination networks. Under load, the coordination bonds reversibly break to dissipate energy, and the flexible siloxane chains work together to homogenize internal stress. This dynamic crosslinking and flexible chain design significantly improves the impact toughness of the polyurethane screen plate.

[0023] 2. The present invention also utilizes stepped heating to drive the migration of siloxanes and perfluoroalkyl groups to the interface to form a fluorosilicone composite microphase region. This microphase region, combined with the three-dimensional topological structure of the hyperbranched framework, constructs a dense hydrophobic anti-sticking barrier, which overcomes the limitation of easy failure of a single anti-sticking phase, significantly reduces the interfacial adhesion work, and provides long-term anti-clogging capability for the harsh working conditions of polyurethane screen plates.

[0024] 3. The present invention also utilizes a fluorinated pyridine-terminated hyperbranching modifier to participate in crosslinking, thereby achieving topological confinement of the coordination network by the three-dimensional skeleton. Its multiple active sites complex with metals to form physical-chemical dual crosslinking, strengthening the interpenetrating network, stabilizing the mechanical properties of the polyurethane sieve material, and resisting structural deformation caused by high-frequency vibration. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The hydroxyl-terminated polydimethylsiloxane used in this invention was purchased from Wuhan Yuancheng Chemical Co., Ltd., with model number [model number missing], an effective ingredient content of 98.1%, and brand name [brand name missing].

[0027] Example 1

[0028] This embodiment provides a method for preparing an impact-resistant and anti-clogging polyurethane sieve plate, including the following steps:

[0029] Step I: Preparation of fluorine-containing terminal pyridine hyperbranched modifier

[0030] Weigh 20g of trimethylolpropane triacrylate, 30g of diethanolamine and 800mL of methanol and place them in a reaction vessel under nitrogen atmosphere and stir. Heat the reaction vessel to 50℃ and keep it at that temperature for 20h. After the reaction is completed, wait for the reaction to cool to room temperature and transfer the reaction solution to a rotary evaporator at 40℃. Remove the solvent by rotary evaporation under reduced pressure to obtain the terminal hydroxyl hyperbranched intermediate.

[0031] Weigh 50g of the hydroxyl-terminated hyperbranched intermediate, 250mL of toluene, and 150mL of N,N-dimethylformamide and place them in a reaction vessel and stir. Add 1g of p-toluenesulfonic acid and 20g of nicotinic acid. Heat the reaction vessel to 110℃ and keep it at this temperature for 4 hours. Add 60g of perfluorohexanoic acid and keep it at this temperature for 3 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, then drop the reaction solution into diethyl ether to precipitate. Filter the solution, wash the filter cake twice with diethyl ether, transfer it to an oven at 30℃, and dry it to constant weight to obtain a fluorinated pyridine-terminated hyperbranched modifier.

[0032] By using the Michael addition reaction of trimethylolpropane triacrylate with diethanolamine, and utilizing the nucleophilic addition of secondary amine groups to the double bonds of acrylate, a hyperbranched intermediate skeleton with a highly branched structure and a large number of terminal hydroxyl groups was constructed. Subsequently, under the catalysis of p-toluenesulfonic acid, the terminal hydroxyl groups of the intermediate underwent esterification condensation reactions with nicotinic acid and perfluorohexanoic acid, respectively, thereby synergistically introducing pyridine functional groups with coordination ability and perfluoroalkyl segments with low surface energy into the outer layer of the hyperbranched structure.

[0033] The three-dimensional hyperbranched framework constructed by this reaction provides a steric hindrance and stress dispersion network for the polyurethane matrix. The pyridine groups introduced in the outer layer subsequently form dynamic reversible coordination bonds with the zinc ions in the system, constructing a micro-stress dissipation mechanism based on sacrificial bonds, which synergistically enhances the material's impact toughness and fatigue fracture resistance. The perfluoroalkyl segments drive the hyperbranched modifier to migrate and accumulate directionally to the curing interface, forming a micro-nano hydrophobic interface layer with extremely low surface energy. This reduces the solid-liquid adhesion work on the sieve plate surface, blocks the adsorption and agglomeration of wet and sticky mineral materials, and improves the anti-adhesion and anti-clogging performance of the polyurethane sieve plate.

[0034] Step II: Preparation of terminal isocyanate prepolymer component A

[0035] Weigh 100g of polytetrahydrofuran and 5g of hydroxyl-terminated polydimethylsiloxane and place them in a nitrogen-protected reactor and stir. Heat the reactor to 55°C, add isophorone diisocyanate at 0.55 times the total molar amount of hydroxyl groups in polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane, add 0.1g of dibutyltin dilaurate, heat the reactor to 75°C, and stir for 3 hours to obtain isocyanate-terminated prepolymer component A.

[0036] Step III: Preparation of component B of the coordination curing agent

[0037] Antioxidant 1010, ultraviolet absorber UV-326, N,N'-2,2',6,6'-tetraisopropylphenylcarbodiimide and polyvinyl isobutyl ether were mixed evenly in a mass ratio of 2:1:2:0.5 to obtain the excipients for later use.

[0038] Weigh out 80g of dimethylglyoxime, 60g of 1,4-butanediol, 10g of 2,6-pyridinediethanol, 40g of sorbitan monooleate, 10g of fluorinated pyridine hyperbranched modifier, and 5g of excipients and place them in a reaction vessel and stir. Add 50mL of 20wt% zinc chloride tetrahydrofuran solution, heat the reaction vessel to 35℃, and keep it at this temperature for 2h. Then heat the reaction vessel to 60℃, remove the solvent by vacuum distillation, and allow it to stand to remove bubbles to obtain component B of the coordination curing agent.

[0039] Step IV: Preparation of polyurethane sieve plates

[0040] Weigh 100g of terminal isocyanate prepolymer component A and place it in a reactor and stir. Heat the reactor to 65°C, add 10g of coordination curing agent component B preheated to 45°C, stir evenly, and pour into a sieve plate mold preheated to 75°C. Keep the mold at 75°C for 1.5 hours, transfer the sieve plate mold to a vacuum drying oven at 90°C and keep it at that temperature for 3 hours. Then, heat the vacuum drying oven to 115°C and keep it at that temperature for 6 hours. Allow it to cool naturally to room temperature to obtain a polyurethane sieve plate.

[0041] A polyisocyanate-terminated polyurethane prepolymer was synthesized by reacting the terminal hydroxyl groups of polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane with an excess of isophorone diisocyanate through an addition polymerization reaction. Further, a composite curing system containing metal-organic coordination bonds was constructed by complexing zinc ions with nitrogen-containing ligands in dimethylglyoxime, 2,6-pyridinediethanol, and hyperbranching modifiers, and then blending it with chain extender 1,4-butanediol and various excipients. The terminal isocyanate groups of component A of the prepolymer underwent a carbamate reaction with the polyol hydroxyl groups in component B of the curing agent. During a stepped temperature curing process, chain extension and crosslinking of the polymer chains were completed, in situ covalently locking low surface energy fluorine and silicon flexible segments and a zinc-nitrogen dynamic reversible coordination network within the three-dimensional polyurethane elastomer crosslinked backbone.

[0042] Hydroxyl-terminated polydimethylsiloxane is introduced into the main chain of polyurethane prepolymer, and low surface energy siloxane flexible blocks are pre-placed inside the matrix. Furthermore, a dynamic and reversible metal-organic coordination network is constructed by in-situ complexation of nitrogen-containing ligands with zinc ions, which acts as energy dissipation sacrificial bonds under impact loads, endowing the matrix with excellent stress relaxation and resistance to microcrack propagation. The final urethane crosslinking and step-temperature curing coupling process not only tightly locks the high-strength three-dimensional covalent crosslinked skeleton with the high dissipation coordination network, but also uses temperature control to drive the low surface energy fluorine and silicon segments to undergo thermodynamic directional enrichment to the curing interface, constructing a water-resistant composite microphase region with extremely low adhesion work, which significantly improves the impact resistance and anti-clogging performance of polyurethane sieve plates.

[0043] Example 2

[0044] This embodiment provides a method for preparing an impact-resistant and anti-clogging polyurethane sieve plate, including the following steps:

[0045] Step I: Preparation of fluorine-containing terminal pyridine hyperbranched modifier

[0046] Weigh out 30g of trimethylolpropane triacrylate, 45g of diethanolamine and 900mL of methanol and place them in a reaction vessel under nitrogen atmosphere protection and stir. Heat the reaction vessel to 55℃ and keep it at this temperature for 22h. After the reaction is completed, wait for the reaction to cool to room temperature and transfer the reaction solution to a rotary evaporator at 45℃. Remove the solvent by rotary evaporation under reduced pressure to obtain the terminal hydroxyl hyperbranched intermediate.

[0047] Weigh 60g of the hydroxyl-terminated hyperbranched intermediate, 300mL of toluene, and 175mL of N,N-dimethylformamide and place them in a reaction vessel and stir. Add 1.5g of p-toluenesulfonic acid and 30g of nicotinic acid. Heat the reaction vessel to 115℃ and keep it at this temperature for 5 hours. Add 70g of perfluorohexanoic acid and keep it at this temperature for 4 hours. After the reaction is complete, wait for the reaction system to cool to room temperature. Drop the reaction solution into diethyl ether to precipitate the precipitate. Filter the precipitate and wash it three times with diethyl ether. Transfer the precipitate to an oven at 35℃ and dry it to constant weight to obtain a fluorinated pyridine-terminated hyperbranched modifier.

[0048] Step II: Preparation of terminal isocyanate prepolymer component A

[0049] Weigh 110g of polytetrahydrofuran and 7.5g of hydroxyl-terminated polydimethylsiloxane and place them in a nitrogen-protected reactor and stir. Heat the reactor to 60°C, add isophorone diisocyanate at 0.55 times the total molar amount of hydroxyl groups in polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane, add 0.15g of dibutyltin dilaurate, heat the reactor to 80°C, and stir for 3.5h to obtain component A of the isocyanate-terminated prepolymer.

[0050] Step III: Preparation of component B of the coordination curing agent

[0051] Antioxidant 1010, ultraviolet absorber UV-326, N,N'-2,2',6,6'-tetraisopropylphenylcarbodiimide and polyvinyl isobutyl ether were mixed evenly in a mass ratio of 3:2:2.5:0.75 to obtain the excipients for later use.

[0052] Weigh out 90g of dimethylglyoxime, 70g of 1,4-butanediol, 20g of 2,6-pyridinediethanol, 50g of sorbitan monooleate, 15g of fluorinated pyridine hyperbranched modifier, and 7.5g of excipients and place them in a reaction vessel and stir. Add 60mL of 25wt% zinc chloride tetrahydrofuran solution, heat the reaction vessel to 40℃, and keep it at this temperature for 3h. Then heat the reaction vessel to 70℃, remove the solvent by vacuum distillation, and allow it to stand to remove bubbles to obtain component B of the coordination curing agent.

[0053] Step IV: Preparation of polyurethane sieve plates

[0054] Weigh 110g of terminal isocyanate prepolymer component A and place it in a reaction vessel and stir. Heat the reaction vessel to 70°C, add 15g of coordination curing agent component B preheated to 50°C, stir evenly, and pour into a sieve plate mold preheated to 77°C. Keep the mold at 80°C for 2 hours, transfer the sieve plate mold to a vacuum drying oven at 95°C and keep it at that temperature for 4 hours. Then, heat the vacuum drying oven to 120°C and keep it at that temperature for 7 hours. Allow it to cool naturally to room temperature to obtain a polyurethane sieve plate.

[0055] Example 3

[0056] This embodiment provides a method for preparing an impact-resistant and anti-clogging polyurethane sieve plate, including the following steps:

[0057] Step I: Preparation of fluorinated terminal pyridine hyperbranched modifier

[0058] Weigh 40g of trimethylolpropane triacrylate, 60g of diethanolamine and 1000mL of methanol and place them in a reaction vessel under nitrogen atmosphere and stir. Heat the reaction vessel to 60℃ and keep it at this temperature for 24h. After the reaction is completed, wait for the reaction to cool to room temperature and transfer the reaction solution to a rotary evaporator at 50℃. Remove the solvent by rotary evaporation under reduced pressure to obtain the terminal hydroxyl hyperbranched intermediate.

[0059] Weigh 70g of the hydroxyl-terminated hyperbranched intermediate, 350mL of toluene, and 200mL of N,N-dimethylformamide and place them in a reaction vessel and stir. Add 2g of p-toluenesulfonic acid and 40g of nicotinic acid. Heat the reaction vessel to 120℃ and keep it at this temperature for 6 hours. Add 80g of perfluorohexanoic acid and keep it at this temperature for 5 hours. After the reaction is complete, wait for the reaction system to cool to room temperature. Drop the reaction solution into diethyl ether to precipitate the precipitate. Filter the precipitate and wash it four times with diethyl ether. Transfer the precipitate to an oven at 40℃ and dry it to constant weight to obtain a fluorinated pyridine-terminated hyperbranched modifier.

[0060] Step II: Preparation of terminal isocyanate prepolymer component A

[0061] Weigh 120g of polytetrahydrofuran and 10g of hydroxyl-terminated polydimethylsiloxane and place them in a nitrogen-protected reactor and stir. Heat the reactor to 65°C, add isophorone diisocyanate at 0.55 times the total molar amount of hydroxyl groups in polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane, add 0.2g of dibutyltin dilaurate, heat the reactor to 85°C, and stir for 4 hours to obtain isocyanate-terminated prepolymer component A.

[0062] Step III: Preparation of component B of the coordination curing agent

[0063] Antioxidant 1010, ultraviolet absorber UV-326, N,N'-2,2',6,6'-tetraisopropylphenylcarbodiimide and polyvinyl isobutyl ether were mixed evenly in a mass ratio of 4:3:3:1 to obtain the excipients for later use.

[0064] Weigh out 100g of dimethylglyoxime, 80g of 1,4-butanediol, 30g of 2,6-pyridinediethanol, 60g of sorbitan monooleate, 20g of fluorinated pyridine hyperbranched modifier, and 10g of excipients and place them in a reaction vessel and stir. Add 70mL of 30wt% zinc chloride tetrahydrofuran solution, heat the reaction vessel to 45℃, and keep it at this temperature for 4h. Then heat the reaction vessel to 80℃, remove the solvent by vacuum distillation, and allow it to stand to remove bubbles to obtain component B of the coordination curing agent.

[0065] Step IV: Preparation of polyurethane sieve plates

[0066] Weigh 120g of terminal isocyanate prepolymer component A and place it in a reactor and stir. Heat the reactor to 75°C, add 20g of coordination curing agent component B preheated to 55°C, stir evenly, and pour into a sieve plate mold preheated to 80°C. Keep the mold at 85°C for 2 hours, transfer the sieve plate mold to a vacuum drying oven at 100°C and keep it at that temperature for 5 hours. Then, heat the vacuum drying oven to 125°C and keep it at that temperature for 8 hours. Allow it to cool naturally to room temperature to obtain a polyurethane sieve plate.

[0067] Comparative Example 1

[0068] The difference between this comparative example and Example 3 is that, in step II, when preparing the terminal isocyanate prepolymer component A, the use of terminal hydroxyl polydimethylsiloxane was omitted.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 3 is that the zinc chloride tetrahydrofuran solution was omitted when preparing the coordination curing agent component B in step III.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 3 is that, in step III, when preparing component B of the coordination curing agent, the use of the fluorinated terminal pyridine hyperbranching modifier is omitted.

[0073] Performance testing:

[0074] The hardness and relative volumetric wear of the polyurethane sieves prepared in Examples 1-3 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 33091-2016 "Polyurethane Sieve Plates".

[0075] The notched impact strength of the polyurethane sieve plates prepared in Examples 1-3 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 1043.1-2008 "Determination of impact properties of simply supported beams of plastics - Part 1: Non-instrumental impact test".

[0076] The water contact angles of the polyurethane sieves prepared in Examples 1-3 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 30693-2014 "Measurement of the contact angle between plastic film and water".

[0077] The total effective number of sieve holes of the polyurethane sieve plates prepared in Examples 1-3 and Comparative Examples 1-3 was statistically analyzed. Quartz sand with a moisture content of 8-12% and a particle size of 0.10-0.15 mm was uniformly added to the polyurethane sieve plate and sieved for 10-15 minutes with a vibration frequency of 1500-1800 times / min and an amplitude of 3-5 mm. After sieving, the number of blocked sieve holes was counted and calculated according to the blockage rate (%) = number of blocked sieve holes / total effective number of sieve holes × 100%. The specific data are shown in Table 1.

[0078] Table 1 - Performance Test Data for Each Sample

[0079]

[0080] Data Analysis:

[0081] Analysis of the data in the table above shows that the polyurethane sieve plate prepared by this invention has a hardness of 94 Shore A and a notched impact strength of 58.5 kJ / m². 2 The relative volumetric wear is 65mm. 3 With a water contact angle of 124° and a pore blockage rate of 2.5%, all performance characteristics are superior to the comparative example.

[0082] The present invention first synthesizes a fluorinated pyridine-terminated hyperbranching modifier, and then copolymerizes polyether and siloxane diol to form a terminal isocyanate prepolymer component A. Next, the fluorinated pyridine-terminated hyperbranching modifier, nitrogen-containing ligand and zinc salt are complexed to obtain a coordination curing agent component B. Finally, the two components are blended and cast, and crosslinked by step temperature curing to construct a polyurethane sieve plate with embedded coordination sacrificial bonds and a surface rich in fluorine and silicon phase. This not only improves the impact resistance of the polyurethane sieve plate, but also improves its anti-clogging ability.

[0083] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing an impact-resistant and anti-clogging polyurethane sieve plate, characterized in that, Includes the following steps: Step 1: Place polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane in a nitrogen-protected reactor and stir. Heat the reactor to 55-65°C, add isophorone diisocyanate and dibutyltin dilaurate, heat the reactor to 75-85°C, and stir for 3-4 hours to obtain isocyanate-terminated prepolymer component A. Step 2: Dimethylglyoxime, 1,4-butanediol, 2,6-pyridinediethanol, sorbitan monooleate, fluorinated pyridine hyperbranched modifier and excipients are placed in a reaction vessel and stirred. Zinc chloride tetrahydrofuran solution is added. The reaction vessel is heated to 35-45℃ and kept at this temperature for 2-4 hours. The solvent is removed under reduced pressure, and the mixture is allowed to stand to remove bubbles, thus obtaining component B of the coordination curing agent. Step 3: Place the terminal isocyanate prepolymer component A in a reactor and stir. Heat the reactor to 65-75℃, add the coordination curing agent component B preheated to 45-55℃, stir evenly, and pour into a sieve plate mold preheated to 75-80℃. Keep the mold at 75-85℃ for 1.5-2 hours. The polyurethane sieve plate is obtained by step heat treatment.

2. The method for preparing an impact-resistant and anti-clogging polyurethane sieve plate according to claim 1, characterized in that, In step one, the weight ratio of the polytetrahydrofuran, hydroxyl-terminated polydimethylsiloxane, and dibutyltin dilaurate is 10-12: 0.5-1:0.01-0.02, wherein the molar amount of isophorone diisocyanate is 0.55 times the total molar amount of polytetrahydrofuran and hydroxyl-terminated polydimethylsiloxane, and the number average molecular weight of polytetrahydrofuran is 1000-2000.

3. The method for preparing an impact-resistant and anti-clogging polyurethane sieve plate according to claim 1, characterized in that, In step two, the ratio of dimethylglyoxime, 1,4-butanediol, 2,6-pyridinediethanol, sorbitan monooleate, fluorinated pyridine hyperbranching modifier, excipients, and zinc chloride tetrahydrofuran solution is 8-10g:6-8g:1-3g:4-6g:1-2g:0.5-1g:5-7mL, and the concentration of zinc chloride tetrahydrofuran solution is 20-30wt%.

4. The method for preparing an impact-resistant and anti-clogging polyurethane sieve plate according to claim 1, characterized in that, In step three, the weight ratio of the terminal isocyanate prepolymer component A to the coordination curing agent component B is 10-12:1-2. The stepped heat treatment step includes: transferring the sieve plate mold to a vacuum drying oven at a temperature of 90-100℃ and keeping it at that temperature for 3-5 hours, then raising the temperature of the vacuum drying oven to 115-125℃ and keeping it at that temperature for 6-8 hours, and then naturally cooling it to room temperature to obtain a polyurethane sieve plate.

5. The method for preparing an impact-resistant and anti-clogging polyurethane sieve plate according to claim 1, characterized in that, The fluorinated terminal pyridine hyperbranched modifier is prepared by the following steps: A1. Trimethylolpropane triacrylate, diethanolamine and methanol were placed in a reaction vessel under nitrogen atmosphere and stirred. The reaction vessel was heated to 50-60℃ and kept at the temperature for 20-24h. The end-hydroxyl hyperbranched intermediate was obtained by post-treatment. A2. Place the hydroxyl-terminated hyperbranched intermediate, toluene, and N,N-dimethylformamide in a reaction vessel and stir. Add p-toluenesulfonic acid and nicotinic acid. Heat the reaction vessel to 110-120℃ and maintain the temperature for 4-6 hours. Add perfluorohexanoic acid and maintain the temperature for 3-5 hours. Post-treatment yields a fluorinated pyridine-terminated hyperbranched modifier.

6. The method for preparing an impact-resistant and anti-clogging polyurethane sieve plate according to claim 5, characterized in that, In step A1, the ratio of trimethylolpropane triacrylate, diethanolamine, and methanol is 2-4g:3-6g:80-100mL; in step A2, the ratio of the terminal hydroxyl hyperbranched intermediate, toluene, N,N-dimethylformamide, p-toluenesulfonic acid, nicotinic acid, and perfluorohexanoic acid is 5-7g:25-35mL:15-20mL:0.1-0.2g:2-4g:6-8g.

7. A polyurethane sieve plate with impact resistance and anti-clogging properties, characterized in that, The impact-resistant and anti-clogging polyurethane sieve plate is prepared by the method described in any one of claims 1-6.

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