Fiber reinforced and toughened flexible resin for printing plate and preparation method of fiber reinforced and toughened flexible resin

Abstract

The invention relates to the technical field of printing plate materials, in particular to fiber-reinforced and toughened flexible resin for a printing plate and a preparation method of the fiber-reinforced and toughened flexible resin. The flexible resin is used for solving the problems that the existing flexible resin for the printing plate is insufficient in impact resistance and relatively low in bending strength and tensile strength. The flexible resin is prepared from POSS grafted polyurethane acrylate and polyimide grafted aramid fiber, p-hydroxybenzamido-POSS is synthesized and polymerized with polyethylene glycol, 2, 2-bis (4-isocyanate phenyl) hexafluoropropane and diethylene glycol to obtain POSS grafted polyurethane acrylate, POSS can be used as a physical crosslinking point to hinder molecular chain sliding, so that the flexibility of the flexible resin is improved, and the flexibility of the flexible resin is improved. According to the flexible resin, the tensile strength of the resin is remarkably improved, the polyimide is grafted on the surface of the aramid fiber, the tensile strength and bending modulus of the flexible resin are improved, the stability and durability of the flexible resin in printing production are remarkably improved, and the stability and consistency of product quality are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of printing plate materials, and particularly relates to a fiber-reinforced and toughened flexible resin for printing plates and a preparation method thereof. BACKGROUND

[0002] People have higher and higher requirements for the performance of printing plate materials, not only to meet the requirements of aesthetics and quality, but also to have better durability and toughness. Flexible resin, as a kind of synthetic material that can bend and has flexibility, is widely used in various high-grade printing plates and other flexible electronic products. However, the traditional flexible resin material often has insufficient impact resistance, low bending strength and tensile strength, and is prone to breakage during production or use, which affects its service life and application range. Therefore, the present application provides a fiber-reinforced and toughened flexible resin for printing plates and a preparation method thereof, which improves the mechanical properties of the flexible resin and can meet the high requirements of modern printing plates and other flexible products. SUMMARY

[0003] In order to overcome the above technical problems, the purpose of the present application is to provide a fiber-reinforced and toughened flexible resin for printing plates and a preparation method thereof, which solves the problems of insufficient impact resistance, low bending strength and tensile strength of the existing flexible resin for printing plates.

[0004] The purpose of the present application can be achieved by the following technical solutions: In a first aspect, the present application provides a fiber-reinforced and toughened flexible resin for printing plates, comprising the following weight parts: POSS grafted polyurethane acrylate 45-50 parts, polyimide grafted aramid fiber 15-20 parts.

[0005] The POSS grafted polyurethane acrylate is prepared by the following steps: Step A1: γ-aminopropyltriethoxysilane, chloropropanol, triethylamine and toluene are added to a double-port flask equipped with a mechanical stirrer and a thermometer, stirred for 5-10 min, reacted at 50℃ for 5h, filtered, collected liquid after distillation, the liquid is added to a single-port flask equipped with a mechanical stirrer, triethylamine and deionized water are added, stirred at 100-200r / min for 2h, deionized water is removed by reduced pressure distillation, washed with acetone for 3-5 times, filtered, vacuum dried, and hydroxyl POSS is obtained; Step A2: Hydroxy POSS, S-benzyloxycarbonyl-L-cysteine, 4-dimethylaminopyridine and dichloromethane were added into a single-neck flask equipped with a mechanical stirrer, stirred for 10-15 min, ultrasonic for 5-10 min, transferred into an ice bath, N, N'-diisopropylcarbodiimide was added by a syringe, reacted for 10-15 min, removed the ice bath, stirred at 24-26℃ for 16 h, separated and purified by a mixed solvent of petroleum ether and ethyl acetate, dried to obtain the first intermediate; Step A3: The first intermediate and dichloromethane were added into a single-neck flask, nitrogen was introduced for 5 min, under the protection of nitrogen, n-octyl mercaptan, 1,8-diazabicyclo[5.4.0]undec-7-ene, aluminum chloride and hexafluoroisopropanol were added, reacted for 2-4 h, quenched by adding saturated sodium bicarbonate solution, separated and extracted, the organic phase was collected and dried over anhydrous sodium sulfate, filtered and concentrated, separated and purified by a mixed solvent of petroleum ether and ethyl acetate, dried, then added into a single-neck flask equipped with a mechanical stirrer, dichloromethane was added, stirred for 5-10 min, triethylamine was added by a syringe and stirred for 3-4 min, p-hydroxybenzoyl chloride was added dropwise, the dropping speed was controlled, stirred for 4 h, separated and purified by a mixed solvent of petroleum ether and ethyl acetate, dried to obtain p-hydroxybenzoyl amino-POSS; Step A4: Polyethylene glycol, 2,2-bis(4-isocyanatophenyl)hexafluoropropane and N, N-dimethylformamide were added into a two-neck flask equipped with a thermometer and a reflux condenser, nitrogen was introduced for 10 min, pre-polymerized at 80℃ for 2 h, cooled to 70℃, dibutyltin dilaurate and diethylene glycol were added and reacted for 3 h, cooled to 60℃, p-hydroxybenzoyl amino-POSS was added and reacted for 2 h, vacuum dried to obtain POSS grafted polyurethane acrylate.

[0006] As a further scheme of the application: the amount ratio of the γ-aminopropyl triethoxysilane, chloropropanol, triethylamine, toluene, trifluoromethanesulfonic acid and deionized water in step A1 is 18-36 g: 9.4-18.8 g: 10-20 g: 92-184 mL: 4.5-9 g: 60-120 mL.

[0007] As a further scheme of the application: the amount ratio of the hydroxy POSS, S-benzyloxycarbonyl-L-cysteine, 4-dimethylaminopyridine, dichloromethane and N, N'-diisopropylcarbodiimide in step A2 is 1.09-2.18 mmol: 1.09-2.18 mmol: 0.47-0.94 mmol: 10-20 mL: 1.1-2.2 mmol.

[0008] As a further scheme of the application: the volume ratio of petroleum ether to ethyl acetate in the mixed solvent of petroleum ether and ethyl acetate in step A2 is 13:1.

[0009] As a further scheme of the present application: the amount ratio of the first intermediate, dichloromethane, n-octyl mercaptan, 1,8-diazabicyclo[5.4.0]undec-7-ene, aluminum chloride, hexafluoroisopropanol, dichloromethane, triethylamine and p-hydroxybenzoyl chloride in step A3 is 1.34-2.68 mmol: 10-20 mL: 1.5-3 mmol: 0.62-1.24 mmol: 0.5-1 mmol: 10-20 mL: 10-20 mL: 1-2 mmol: 1-2 mmol.

[0010] As a further scheme of the present application: the volume ratio of petroleum ether and ethyl acetate in the mixed solvent of petroleum ether and ethyl acetate in step A3 is 13:1.

[0011] As a further scheme of the present application: the amount ratio of polyethylene glycol, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, N,N-dimethylformamide, dibutyltin dilaurate, diethylene glycol and p-hydroxybenzoyl amino-POSS in step A4 is 10-20 g: 0.02-0.04 mol: 120-240 mL: 0.155-0.31 g: 0.005-0.01 mol: 0.02-0.04 mol.

[0012] As a further scheme of the present application: the model number of the polyethylene glycol in step A4 is PEG2000.

[0013] As a further scheme of the present application: the POSS grafted polyurethane acrylate is prepared by the following steps: Step B1: cut aramid fiber, potassium hydroxide solution, n-tetrabutylammonium bromide and dimethyl sulfoxide are added to a single-neck flask equipped with a mechanical stirrer and a thermometer, stirred at 30℃ for 3-4h, dropwise added with acetone and stirred for 20-30min, vacuum filtered for 5-7 times, and vacuum dried at 24-26℃ in a drying box for 2-3h to obtain pretreated aramid fiber; Step B2: 3-aminopropyltrimethoxysilane, anhydrous ethanol are added to a beaker, stirred for 5-10min, the pH of the tannic acid solution is adjusted to 8.5 with tris(hydroxymethyl)aminomethane and added to the beaker, stirred for 10-15min, and the pretreated aramid fiber is added and immersed for 2h, and after drying, modified aramid fiber is obtained; Step B3: diamino diphenyl ether, N, N-dimethylacetamide are added into a double-port flask equipped with a mechanical stirrer, a thermometer, stirred at 200-300 r / min for 5-10 min, nitrogen is introduced, transferred into an ice bath, phtalic anhydride is added at 5℃, stirred at 300-500 r / min for 3h, triethanolamine is added and stirred for 10-15 min, transferred into a water bath and heated to 40℃, methanol is added, transferred into a beaker, modified aramid fiber is added, stirred for 5-10 min, and reacted for 12h, washed with deionized water for 3-5 times, and dried in a drying box at 100℃ for 3h to obtain polyimide grafted aramid fiber.

[0014] As a further scheme of the application: the amount ratio of the short-cut aramid fiber, potassium hydroxide solution, n-tetrabutyl ammonium bromide, dimethyl sulfoxide and acetone in step B1 is 1.5-3g:4.5-9g:0.15-0.3g:150-300mL:75-150mL.

[0015] As a further scheme of the application: the mass fraction of the potassium hydroxide solution in step B1 is 50%.

[0016] As a further scheme of the application: the amount ratio of the 3-aminopropyltrimethoxysilane, anhydrous ethanol, tannic acid solution and pretreated aramid fiber in step B2 is 2-4g:20-40mL:20-40mL:5-10g.

[0017] As a further scheme of the application: the concentration of the tannic acid solution in step B2 is 2g / L.

[0018] As a further scheme of the application: the amount ratio of the diamino diphenyl ether, N, N-dimethylacetamide, phtalic anhydride, triethanolamine, methanol and modified aramid fiber in step B3 is 0.025-0.05mol:100-200mL:0.025-0.05mol:5.0595-10.119g:300-600mL:2-4g.

[0019] The second aspect relates to a preparation method of a fiber-reinforced and toughened flexible resin for printing plate, comprising the following steps: Step one: according to the weight parts, 45-50 parts of POSS grafted polyurethane acrylate and 15-20 parts of polyimide grafted aramid fiber are weighed and prepared; Step two: the POSS grafted polyurethane acrylate and the polyimide grafted aramid fiber are mixed to obtain the fiber-reinforced and toughened flexible resin for printing plate.

[0020] The application has the following beneficial effects: The present invention discloses a fiber-reinforced and toughened flexible resin for printing plates and its preparation method. POSS is grafted onto polyurethane acrylate to improve the resin's wear resistance and tensile strength. Polyimide is grafted onto the surface of aramid fiber to improve compatibility with the resin matrix and enhance toughness.

[0021] A fiber-reinforced and toughened flexible resin for printing plates was prepared. First, POSS-grafted polyurethane acrylate was prepared. The amino group of γ-aminopropyltriethoxysilane attacked the chlorine atom of chloropropanol, undergoing nucleophilic substitution to generate an intermediate containing silicon-oxygen-carbon bonds. Under the catalysis of trifluoromethanesulfonic acid, the silylethoxy group hydrolyzed to generate silanol. Dehydration condensation between silanols formed Si-O-Si bonds, and the silicon-oxygen bonds further arranged in an ordered manner to form hydroxyl POSS. Under the catalysis of dichloromethane, 4-dimethylaminopyridine activated the carboxylic acid group of S-benzyloxycarbonyl-L-cysteine, forming an active acyl intermediate. This active acyl intermediate underwent esterification with the hydroxyl groups on the surface of hydroxyl POSS, introducing cysteine ​​groups while preserving the cage-like structure of POSS. The sulfur atom of n-octylthiol nucleophilically attacked the amino group in the first intermediate, forming a thioether bond. The aluminum chloride and hexafluoroisopropanol system catalyzed the hydrolysis of the benzyloxycarbonyl group, releasing the amino group. Simultaneously, the high polarity of hexafluoroisopropanol promoted the dissolution of reactants and ion-pair reactions, achieving thiol substitution and... Deprotection occurs simultaneously. p-hydroxybenzoyl chloride undergoes nucleophilic substitution with the amino group of amino POSS to generate a stable amide bond, yielding p-hydroxybenzoylamino-POSS. Catalyzed by dibutyltin dilaurate, the hydroxyl groups of polyvinyl alcohol undergo stepwise polymerization with the isocyanate in hexafluoroisocyanate to generate a polyurethane prepolymer. Diethylene glycol is added for chain extension, and finally p-hydroxybenzoylamino-POSS is added. Through the reaction of hydroxyl groups with isocyanate, POSS is chemically grafted to obtain POSS-grafted polyurethane acrylate. The rigid cage-like structure of POSS can serve as a physical crosslinking point, hindering molecular chain sliding and significantly improving the tensile strength, impact resistance, and wear resistance of the resin. This solves the problem of easy deformation and cracking of traditional flexible resins after long-term use. The soft segment structure of polyurethane and the flexible chain of polyethylene glycol retain the excellent flexibility and bending properties of the resin, which can adapt to the repeated deformation requirements of printing plates in winding, lamination, and other scenarios, avoiding brittleness. Next, polyimide-grafted aramid fibers are prepared. Potassium hydroxide solution hydrolyzes the amide bonds on the surface of the aramid fibers, generating carboxylic acid groups and amino groups. 3-Aminopropyltrimethoxysilane is hydrolyzed to generate silanol, which undergoes a condensation reaction with the carboxylic acid / hydroxyl groups on the pretreated fiber surface to form covalent bonds, simultaneously introducing amino groups. The phenolic hydroxyl groups of tannic acid form hydrogen / ionic bonds with the amino groups on the fiber surface. The polyphenolic structure of tannic acid forms a network coating through oxidative coupling, enhancing surface activity and adhesion. The amino groups of diaminodiphenyl ether and the anhydride groups of pyromellitic dianhydride undergo condensation polymerization in N,N-dimethylacetamide to generate polyamic acid. The carboxyl groups in polyamic acid react with the amino groups on the surface of modified aramid fibers to form amide bonds. During the drying process, the polyamic acid gradually dehydrates and cyclizes into polyimide. At the same time, a dense grafted layer is formed on the fiber surface. Aramid fibers themselves have high modulus and high strength. After grafting, they act as a rigid skeleton, which can effectively bear stress, improve the tensile strength and flexural modulus of flexible resin, and maintain the flexibility of the matrix. The polyimide grafted layer forms a flexible transition layer on the fiber surface, which enhances the interfacial adhesion between the fiber and the resin matrix, inhibits interfacial debonding, improves impact toughness, and reduces the risk of breakage during the printing process. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1:

[0023] This embodiment describes a method for preparing a fiber-reinforced and toughened flexible resin for printing plates, comprising the following steps: Step S1: 18g of γ-aminopropyltriethoxysilane, 9.4g of chloropropanol, 10g of triethylamine and 92mL of toluene were added to a two-necked flask equipped with a mechanical stirrer and a thermometer. The mixture was stirred for 5 min and reacted at 50℃ for 5 h. After filtration and distillation, the liquid was collected and added to a single-necked flask equipped with a mechanical stirrer. 4.5g of trifluoromethanesulfonic acid and 60mL of deionized water were added and the mixture was stirred at 100r / min for 2 h. The deionized water was removed by vacuum distillation, and the mixture was washed three times with acetone, filtered, and dried under vacuum to obtain hydroxyl POSS. Step S2: 1.09 mmol of hydroxyPOSS, 1.09 mmol of S-benzyloxycarbonyl-L-cysteine, 0.47 mmol of 4-dimethylaminopyridine and 10 mL of dichloromethane were added to a single-necked flask equipped with a mechanical stirrer. The mixture was stirred for 10 min, sonicated for 5 min, transferred to an ice bath, and 1.1 mmol of N,N'-diisopropylcarbodiimide was added using a pipette. The mixture was reacted for 10 min, the ice bath was removed, and the mixture was stirred at 24 °C for 16 h. The mixture was then separated and purified using a mixed solvent of petroleum ether and ethyl acetate, and dried to obtain the first intermediate. Step S3: 1.34 mmol of the first intermediate and 10 mL of dichloromethane were added to a single-necked flask, and nitrogen gas was introduced for 5 min. Under nitrogen protection, 1.5 mmol of n-octyl mercaptan, 0.62 mmol of 1,8-diazabicyclo[5.4.0]undec-7-ene, 0.5 mmol of aluminum chloride and 10 mL of hexafluoroisopropanol were added. The reaction was carried out for 2 h, quenched with saturated sodium bicarbonate solution, and extracted by liquid-liquid extraction. The organic phase was collected, dried with anhydrous sodium sulfate, filtered and concentrated, and separated and purified with a mixed solvent of petroleum ether and ethyl acetate. After drying, it was added to a single-necked flask equipped with a mechanical stirrer, and 10 mL of dichloromethane was added. The mixture was stirred for 5 min, and 1 mmol of triethylamine was added with a pipette and stirred for 3 min. 1 mmol of p-hydroxybenzoyl chloride was added dropwise, and the addition rate was controlled. The mixture was stirred for 4 h, separated and purified with a mixed solvent of petroleum ether and ethyl acetate, and dried to obtain p-hydroxybenzoylamino-POSS. Step S4: Add 10g polyethylene glycol, 0.02mol 2,2-bis(4-phenylisocyanate)hexafluoropropane and 120mL N,N-dimethylformamide to a two-necked flask equipped with a thermometer and a reflux condenser. Purge with nitrogen for 10min and prepolymerize at 80℃ for 2h. Cool to 70℃ and add 0.155g dibutyltin dilaurate and 0.005mol diethylene glycol. React for 3h. Cool to 60℃ and add 0.02mol p-hydroxybenzoylamino-POSS. React for 2h. Dry under vacuum to obtain POSS-grafted polyurethane acrylate. Step S5: Add 1.5g of chopped aramid fiber, 4.5g of potassium hydroxide solution, 0.15g of tetrabutylammonium bromide and 150mL of dimethyl sulfoxide to a single-necked flask equipped with a mechanical stirrer and a thermometer. Stir at 30℃ for 3h, add 75mL of acetone dropwise and stir for 20min, vacuum filter 5 times, place in a drying oven and vacuum dry at 24℃ for 2h to obtain pretreated aramid fiber; Step S6: Add 2g of 3-aminopropyltrimethoxysilane and 20mL of anhydrous ethanol to a beaker and stir for 5min. Adjust the pH of 20mL of tannic acid solution to 8.5 with tris(hydroxymethyl)aminomethane and add it to the beaker. Stir for 10min. Add 5g of pretreated aramid fiber and impregnate for 2h. After drying, the modified aramid fiber is obtained. Step S7: Add 0.025 mol diaminodiphenyl ether and 100 mL N,N-dimethylacetamide to a two-necked flask equipped with a mechanical stirrer and thermometer. Stir at 200 r / min for 5 min, purge with nitrogen, transfer to an ice bath, add 0.025 mol pyromellitic dianhydride at 5 °C, stir at 300 r / min for 3 h, add 5.0595 g triethanolamine and stir for 10 min, transfer to a water bath and heat to 40 °C, add 300 mL methanol, transfer to a beaker and add 2 g modified aramid fiber, stir for 5 min, react for 12 h, wash 3 times with deionized water, place in a drying oven and dry at 100 °C for 3 h to obtain polyimide grafted aramid fiber; Step S8: Weigh out 45 parts of POSS grafted polyurethane acrylate and 15 parts of polyimide grafted aramid fiber according to the weight ratio, and set aside. Step S9: Mix POSS-grafted polyurethane acrylate and polyimide-grafted aramid fibers to obtain a fiber-reinforced and toughened flexible resin for printing plates. Example 2:

[0024] This embodiment describes a method for preparing a fiber-reinforced and toughened flexible resin for printing plates, comprising the following steps: Step S1: 27g of γ-aminopropyltriethoxysilane, 14.1g of chloropropanol, 15g of triethylamine and 138mL of toluene were added to a two-necked flask equipped with a mechanical stirrer and a thermometer. The mixture was stirred for 7 min and reacted at 50℃ for 5 h. After filtration and distillation, the liquid was collected and added to a single-necked flask equipped with a mechanical stirrer. 6.75g of trifluoromethanesulfonic acid and 90mL of deionized water were added and the mixture was stirred at 150r / min for 2 h. The deionized water was removed by vacuum distillation, and the mixture was washed four times with acetone, filtered, and dried under vacuum to obtain hydroxyl POSS. Step S2: 1.635 mmol of hydroxyPOSS, 1.635 mmol of S-benzyloxycarbonyl-L-cysteine, 0.705 mmol of 4-dimethylaminopyridine and 15 mL of dichloromethane were added to a single-necked flask equipped with a mechanical stirrer. The mixture was stirred for 13 min, sonicated for 7 min, transferred to an ice bath, and 1.65 mmol of N,N'-diisopropylcarbodiimide was added using a pipette. The mixture was reacted for 13 min, the ice bath was removed, and the mixture was stirred at 25 °C for 16 h. The mixture was then separated and purified using a mixed solvent of petroleum ether and ethyl acetate, dried, and the first intermediate was obtained. Step S3: Add 2.01 mmol of the first intermediate and 15 mL of dichloromethane to a single-necked flask, purge with nitrogen for 5 min, and under nitrogen protection, add 2.25 mmol of n-octyl mercaptan, 0.93 mmol of 1,8-diazabicyclo[5.4.0]undec-7-ene, 0.75 mmol of aluminum chloride and 15 mL of hexafluoroisopropanol. React for 3 h, quench with saturated sodium bicarbonate solution, extract by separation, collect the organic phase, dry with anhydrous sodium sulfate, filter and concentrate, separate and purify with a mixed solvent of petroleum ether and ethyl acetate, dry and add to a single-necked flask equipped with a mechanical stirrer, add 15 mL of dichloromethane, stir for 7 min, add 1.5 mmol of triethylamine with a pipette and stir for 3 min, add 1.5 mmol of p-hydroxybenzoyl chloride dropwise, control the dropping rate, stir for 4 h, separate and purify with a mixed solvent of petroleum ether and ethyl acetate, dry to obtain p-hydroxybenzoylamino-POSS; Step S4: Add 15g polyethylene glycol, 0.03mol 2,2-bis(4-phenylisocyanate)hexafluoropropane and 180mL N,N-dimethylformamide to a two-necked flask equipped with a thermometer and a reflux condenser. Purge with nitrogen for 10min and prepolymerize at 80℃ for 2h. Cool to 70℃ and add 0.2325g dibutyltin dilaurate and 0.0075mol diethylene glycol. React for 3h. Cool to 60℃ and add 0.03mol p-hydroxybenzoamide-POSS. React for 2h. Dry under vacuum to obtain POSS-grafted polyurethane acrylate. Step S5: Add 2.25g of chopped aramid fibers, 6.75g of potassium hydroxide solution, 0.225g of tetrabutylammonium bromide and 225mL of dimethyl sulfoxide to a single-necked flask equipped with a mechanical stirrer and a thermometer. Stir at 30℃ for 3.5h, add 113mL of acetone dropwise and stir for 25min, vacuum filter 6 times, place in a drying oven and vacuum dry at 25℃ for 2.5h to obtain pretreated aramid fibers; Step S6: Add 3g of 3-aminopropyltrimethoxysilane and 30mL of anhydrous ethanol to a beaker and stir for 7min. Adjust the pH of 30mL of tannic acid solution to 8.5 with tris(hydroxymethyl)aminomethane and add it to the beaker. Stir for 13min. Add 7.5g of pretreated aramid fiber and impregnate for 2h. After drying, the modified aramid fiber is obtained. Step S7: Add 0.0375 mol diaminodiphenyl ether and 150 mL N,N-dimethylacetamide to a two-necked flask equipped with a mechanical stirrer and thermometer. Stir at 250 r / min for 7 min, purge with nitrogen, transfer to an ice bath, add 0.0375 mol pyromellitic dianhydride at 5 °C, stir at 400 r / min for 3 h, add 7.589 g triethanolamine and stir for 13 min, transfer to a water bath and heat to 40 °C, add 450 mL methanol, transfer to a beaker and add 3 g modified aramid fiber, stir for 7 min, react for 12 h, wash 4 times with deionized water, place in a drying oven and dry at 100 °C for 3 h to obtain polyimide grafted aramid fiber; Step S8: Weigh out 47.5 parts of POSS-grafted polyurethane acrylate and 17.5 parts of polyimide-grafted aramid fiber according to the weight ratio, and set aside. Step S9: Mix POSS-grafted polyurethane acrylate and polyimide-grafted aramid fibers to obtain a fiber-reinforced and toughened flexible resin for printing plates. Example 3:

[0025] This embodiment describes a method for preparing a fiber-reinforced and toughened flexible resin for printing plates, comprising the following steps: Step S1: 36g of γ-aminopropyltriethoxysilane, 18.8g of chloropropanol, 20g of triethylamine and 184mL of toluene were added to a two-necked flask equipped with a mechanical stirrer and a thermometer. The mixture was stirred for 10 min and reacted at 50℃ for 5 h. After filtration and distillation, the liquid was collected and added to a single-necked flask equipped with a mechanical stirrer. 9g of trifluoromethanesulfonic acid and 120mL of deionized water were added and the mixture was stirred at 200r / min for 2 h. The deionized water was removed by vacuum distillation. The mixture was washed 5 times with acetone, filtered, and dried under vacuum to obtain hydroxyl POSS. Step S2: 2.18 mmol of hydroxyPOSS, 2.18 mmol of S-benzyloxycarbonyl-L-cysteine, 0.94 mmol of 4-dimethylaminopyridine and 20 mL of dichloromethane were added to a single-necked flask equipped with a mechanical stirrer. The mixture was stirred for 15 min, sonicated for 10 min, transferred to an ice bath, and 2.2 mmol of N,N'-diisopropylcarbodiimide was added using a pipette. The mixture was reacted for 15 min, the ice bath was removed, and the mixture was stirred at 26 °C for 16 h. The mixture was then separated and purified using a mixed solvent of petroleum ether and ethyl acetate, and dried to obtain the first intermediate. Step S3: Add 2.68 mmol of the first intermediate and 20 mL of dichloromethane to a single-necked flask, purge with nitrogen for 5 min, and under nitrogen protection, add 3 mmol of n-octyl mercaptan, 1.24 mmol of 1,8-diazabicyclo[5.4.0]undec-7-ene, 1 mmol of aluminum chloride and 20 mL of hexafluoroisopropanol. React for 4 h, quench with saturated sodium bicarbonate solution, extract by separation, collect the organic phase, dry with anhydrous sodium sulfate, filter and concentrate, separate and purify with a mixed solvent of petroleum ether and ethyl acetate, dry and add to a single-necked flask equipped with a mechanical stirrer, add 20 mL of dichloromethane, stir for 10 min, add 2 mmol of triethylamine with a pipette and stir for 4 min, add 2 mmol of p-hydroxybenzoyl chloride dropwise, control the dropping rate, stir for 4 h, separate and purify with a mixed solvent of petroleum ether and ethyl acetate, dry to obtain p-hydroxybenzoylamino-POSS; Step S4: Add 20g polyethylene glycol, 0.04mol 2,2-bis(4-phenylisocyanate)hexafluoropropane and 240mL N,N-dimethylformamide to a two-necked flask equipped with a thermometer and a reflux condenser. Purge with nitrogen for 10min and prepolymerize at 80℃ for 2h. Cool to 70℃ and add 0.31g dibutyltin dilaurate and 0.01mol diethylene glycol. React for 3h. Cool to 60℃ and add 0.04mol p-hydroxybenzoamide-POSS. React for 2h. Dry under vacuum to obtain POSS-grafted polyurethane acrylate. Step S5: Add 3g of chopped aramid fiber, 9g of potassium hydroxide solution, 0.3g of tetrabutylammonium bromide and 300mL of dimethyl sulfoxide to a single-necked flask equipped with a mechanical stirrer and a thermometer. Stir at 30℃ for 4h, add 150mL of acetone dropwise and stir for 30min, vacuum filter 7 times, place in a drying oven and vacuum dry at 26℃ for 3h to obtain pretreated aramid fiber; Step S6: Add 4g of 3-aminopropyltrimethoxysilane and 40mL of anhydrous ethanol to a beaker and stir for 10min. Adjust the pH of 40mL of tannic acid solution to 8.5 with tris(hydroxymethyl)aminomethane and add it to the beaker. Stir for 15min. Add 10g of pretreated aramid fiber and impregnate for 2h. After drying, the modified aramid fiber is obtained. Step S7: Add 0.05 mol of diaminodiphenyl ether and 200 mL of N,N-dimethylacetamide to a two-necked flask equipped with a mechanical stirrer and thermometer. Stir at 300 r / min for 10 min, purge with nitrogen, transfer to an ice bath, add 0.05 mol of pyromellitic dianhydride at 5 °C, stir at 500 r / min for 3 h, add 10.119 g of triethanolamine and stir for 15 min, transfer to a water bath and heat to 40 °C, add 600 mL of methanol, transfer to a beaker and add 4 g of modified aramid fiber, stir for 10 min, react for 12 h, wash 5 times with deionized water, place in a drying oven and dry at 100 °C for 3 h to obtain polyimide-grafted aramid fiber; Step S8: Weigh out 50 parts of POSS grafted polyurethane acrylate and 20 parts of polyimide grafted aramid fiber according to the weight ratio, and set aside. Step S9: Mix POSS-grafted polyurethane acrylate and polyimide-grafted aramid fibers to obtain a fiber-reinforced and toughened flexible resin for printing plates.

[0026] Comparative Example 1: This comparative example illustrates a method for preparing a fiber-reinforced and toughened flexible resin for printing plates, comprising the following steps: Step S1: 36g of γ-aminopropyltriethoxysilane, 18.8g of chloropropanol, 20g of triethylamine and 184mL of toluene were added to a two-necked flask equipped with a mechanical stirrer and a thermometer. The mixture was stirred for 10 min and reacted at 50℃ for 5 h. After filtration and distillation, the liquid was collected and added to a single-necked flask equipped with a mechanical stirrer. 9g of trifluoromethanesulfonic acid and 120mL of deionized water were added and the mixture was stirred at 200r / min for 2 h. The deionized water was removed by vacuum distillation. The mixture was washed 5 times with acetone, filtered, and dried under vacuum to obtain hydroxyl POSS. Step S2: 2.18 mmol of hydroxyPOSS, 2.18 mmol of S-benzyloxycarbonyl-L-cysteine, 0.94 mmol of 4-dimethylaminopyridine and 20 mL of dichloromethane were added to a single-necked flask equipped with a mechanical stirrer. The mixture was stirred for 15 min, sonicated for 10 min, transferred to an ice bath, and 2.2 mmol of N,N'-diisopropylcarbodiimide was added using a pipette. The mixture was reacted for 15 min, the ice bath was removed, and the mixture was stirred at 26 °C for 16 h. The mixture was then separated and purified using a mixed solvent of petroleum ether and ethyl acetate, and dried to obtain the first intermediate. Step S3: Add 2.68 mmol of the first intermediate and 20 mL of dichloromethane to a single-necked flask, purge with nitrogen for 5 min, and under nitrogen protection, add 3 mmol of n-octyl mercaptan, 1.24 mmol of 1,8-diazabicyclo[5.4.0]undec-7-ene, 1 mmol of aluminum chloride and 20 mL of hexafluoroisopropanol. React for 4 h, quench with saturated sodium bicarbonate solution, extract by separation, collect the organic phase, dry with anhydrous sodium sulfate, filter and concentrate, separate and purify with a mixed solvent of petroleum ether and ethyl acetate, dry and add to a single-necked flask equipped with a mechanical stirrer, add 20 mL of dichloromethane, stir for 10 min, add 2 mmol of triethylamine with a pipette and stir for 4 min, add 2 mmol of p-hydroxybenzoyl chloride dropwise, control the dropping rate, stir for 4 h, separate and purify with a mixed solvent of petroleum ether and ethyl acetate, dry to obtain p-hydroxybenzoylamino-POSS; Step S4: Add 20g polyethylene glycol, 0.04mol 2,2-bis(4-phenylisocyanate)hexafluoropropane and 240mL N,N-dimethylformamide to a two-necked flask equipped with a thermometer and a reflux condenser. Purge with nitrogen for 10min and prepolymerize at 80℃ for 2h. Cool to 70℃ and add 0.31g dibutyltin dilaurate and 0.01mol diethylene glycol. React for 3h. Cool to 60℃ and add 0.04mol p-hydroxybenzoamide-POSS. React for 2h. Dry under vacuum to obtain POSS-grafted polyurethane acrylate. Step S5: Add 3g of chopped aramid fiber, 9g of potassium hydroxide solution, 0.3g of tetrabutylammonium bromide and 300mL of dimethyl sulfoxide to a single-necked flask equipped with a mechanical stirrer and a thermometer. Stir at 30℃ for 4h, add 150mL of acetone dropwise and stir for 30min, vacuum filter 7 times, place in a drying oven and vacuum dry at 26℃ for 3h to obtain pretreated aramid fiber; Step S6: Add 4g of 3-aminopropyltrimethoxysilane and 40mL of anhydrous ethanol to a beaker and stir for 10min. Adjust the pH of 40mL of tannic acid solution to 8.5 with tris(hydroxymethyl)aminomethane and add it to the beaker. Stir for 15min. Add 10g of pretreated aramid fiber and impregnate for 2h. After drying, the modified aramid fiber is obtained. Step S7: Weigh out 50 parts of POSS grafted polyurethane acrylate and 20 parts of modified aramid fiber according to the weight ratio, and set aside. Step S8: Mix POSS-grafted polyurethane acrylate and modified aramid fiber to obtain a fiber-reinforced and toughened flexible resin for printing plates.

[0027] Comparative Example 2: This comparative example illustrates a method for preparing a fiber-reinforced and toughened flexible resin for printing plates, comprising the following steps: Step S1: Add 20g polyethylene glycol, 0.04mol 2,2-bis(4-phenylisocyanate)hexafluoropropane and 240mL N,N-dimethylformamide to a two-necked flask equipped with a thermometer and a reflux condenser. Purge with nitrogen for 10min and prepolymerize at 80℃ for 2h. Cool to 70℃ and add 0.31g dibutyltin dilaurate and 0.01mol diethylene glycol. React for 3h. Cool to 60℃ and add 0.04mol 2-hydroxyethyl acrylate. React for 2h. Dry under vacuum to obtain polyurethane acrylate. Step S2: Add 3g of chopped aramid fiber, 9g of potassium hydroxide solution, 0.3g of tetrabutylammonium bromide and 300mL of dimethyl sulfoxide to a single-necked flask equipped with a mechanical stirrer and a thermometer. Stir at 30℃ for 4h, add 150mL of acetone dropwise and stir for 30min, vacuum filter 7 times, place in a drying oven and vacuum dry at 26℃ for 3h to obtain pretreated aramid fiber; Step S3: Add 4g of 3-aminopropyltrimethoxysilane and 40mL of anhydrous ethanol to a beaker and stir for 10min. Adjust the pH of 40mL of tannic acid solution to 8.5 with tris(hydroxymethyl)aminomethane and add it to the beaker. Stir for 15min. Add 10g of pretreated aramid fiber and impregnate for 2h. After drying, the modified aramid fiber is obtained. Step S4: Add 0.05 mol diaminodiphenyl ether and 200 mL N,N-dimethylacetamide to a two-necked flask equipped with a mechanical stirrer and thermometer. Stir at 300 r / min for 10 min, purge with nitrogen, transfer to an ice bath, add 0.05 mol pyromellitic dianhydride at 5 °C, stir at 500 r / min for 3 h, add 10.119 g triethanolamine and stir for 15 min, transfer to a water bath and heat to 40 °C, add 600 mL methanol, transfer to a beaker and add 4 g modified aramid fiber, stir for 10 min, react for 12 h, wash 5 times with deionized water, place in a drying oven and dry at 100 °C for 3 h to obtain polyimide grafted aramid fiber; Step S5: Weigh out 50 parts of polyurethane acrylate and 20 parts of polyimide-grafted aramid fiber according to the weight ratio, and set aside. Step S6: Mix polyurethane acrylate and polyimide grafted aramid fibers to obtain a fiber-reinforced and toughened flexible resin for printing plates.

[0028] Comparative Example 3: This comparative example illustrates a method for preparing a fiber-reinforced and toughened flexible resin for printing plates, comprising the following steps: Step S1: Add 20g polyethylene glycol, 0.04mol 2,2-bis(4-phenylisocyanate)hexafluoropropane and 240mL N,N-dimethylformamide to a two-necked flask equipped with a thermometer and a reflux condenser. Purge with nitrogen for 10min and prepolymerize at 80℃ for 2h. Cool to 70℃ and add 0.31g dibutyltin dilaurate and 0.01mol diethylene glycol. React for 3h. Cool to 60℃ and add 0.04mol 2-hydroxyethyl acrylate. React for 2h. Dry under vacuum to obtain polyurethane acrylate. Step S2: Add 3g of chopped aramid fiber, 9g of potassium hydroxide solution, 0.3g of tetrabutylammonium bromide and 300mL of dimethyl sulfoxide to a single-necked flask equipped with a mechanical stirrer and a thermometer. Stir at 30℃ for 4h, add 150mL of acetone dropwise and stir for 30min, vacuum filter 7 times, place in a drying oven and vacuum dry at 26℃ for 3h to obtain pretreated aramid fiber; Step S3: Add 4g of 3-aminopropyltrimethoxysilane and 40mL of anhydrous ethanol to a beaker and stir for 10min. Adjust the pH of 40mL of tannic acid solution to 8.5 with tris(hydroxymethyl)aminomethane and add it to the beaker. Stir for 15min. Add 10g of pretreated aramid fiber and impregnate for 2h. After drying, the modified aramid fiber is obtained. Step S4: Weigh out 50 parts of polyurethane acrylate and 20 parts of modified aramid fiber according to the weight ratio, and set aside. Step S5: Mix polyurethane acrylate and modified aramid fiber to obtain a fiber-reinforced and toughened flexible resin for printing plates.

[0029] Performance testing The flexible resins of Examples 1-3 and Comparative Examples 1-3, ethyl acetate, and isopropanol were stirred at 1000 r / min for 30 min, vacuum degassed for 20-30 min, loaded into a mold at 5-10 MPa, cured at 60°C for 5 min, heated to 120°C at 2°C / min and cured for 30 min, heated to 180°C at 1°C / min and cured for 10 min, and after cooling, the sample strips were obtained. The specimen strips were subjected to tensile property testing according to GB / T 1040.2-2022; flexural property testing according to GB / T 9341-2008; and impact property testing according to GB / T 1843-2008. The test results are shown in Table 1. Table 1: Schematic diagram of test results for tensile modulus, flexural modulus, and impact strength.

[0030] A 0.5mm thick aluminum plate was selected as the substrate. It was immersed in a 7% sodium hydroxide solution at 50℃ for 30 seconds, washed with water, and then immersed in a 1% hydrochloric acid solution at 30℃. The solution was then subjected to a flow rate of 50 A / dm³. 2 The current density was used for AC electrolysis for 60 seconds in a 20% sulfuric acid solution at 20 A / dm³. 2 The substrate was anodized with direct current for 30 seconds, sealed in NaH2PO4-NaF solution at 60℃ for 30 seconds, washed with water and dried to obtain the substrate. An adhesive layer is coated on the substrate. The formulation of the adhesive layer is 35 parts of flexible resin, 30 parts of ethyl acetate, 20 parts of isopropanol, 10 parts of deionized water, and 1 part of BYK307 from Examples 1-3 and Comparative Examples 1-3. The above components are stirred and dispersed to form a uniform coating liquid. The coating is applied to the substrate by dip coating and then baked in an oven at 200°C for 5 minutes to cure the coating liquid into an adhesive layer, thus obtaining a flatbed printing plate.

[0031] The abrasion resistance of the flatbed printing plate was tested using a special sealed rotating device with chemical and mechanical abrasives. The degree of wear was determined by maintaining a fixed temperature and time, and the results were denoted as A, A-, B+, B, B-, C+, and C. The test results are shown in Table 2. Table 2: Schematic diagram of wear resistance test results

[0032] Referring to the table above, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the flexible resin prepared by grafting POSS with polyurethane acrylate and polyimide with aramid fiber has good tensile and bending properties. Based on the comparison between Example 3 and Comparative Example 1, it can be seen that the impact strength of the flexible resin prepared by POSS grafted polyurethane acrylate and polyimide grafted aramid fiber is higher than that of the flexible resin prepared by POSS grafted polyurethane acrylate and modified aramid fiber, indicating that the flexible resin prepared by POSS grafted polyurethane acrylate and polyimide grafted aramid fiber has excellent impact resistance. Based on the comparison between Example 3 and Comparative Example 2, it can be seen that the impact strength of the flexible resin prepared by POSS grafted polyurethane acrylate and polyimide grafted aramid fiber is higher than that of the flexible resin prepared by polyurethane acrylate and polyimide grafted aramid fiber, indicating that the flexible resin prepared by POSS grafted polyurethane acrylate and polyimide grafted aramid fiber has excellent impact resistance. Based on the comparison between Example 3 and Comparative Example 3, it can be seen that the impact strength of the flexible resin prepared by POSS grafted polyurethane acrylate and polyimide grafted aramid fiber is higher than that of the flexible resin prepared by polyurethane acrylate and modified aramid fiber, indicating that the flexible resin prepared by POSS grafted polyurethane acrylate and polyimide grafted aramid fiber has excellent impact resistance.

[0033] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0034] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A fiber-reinforced and toughened flexible resin for printing plates, characterized in that, Includes the following components by weight: 45-50 parts of POSS grafted polyurethane acrylate and 15-20 parts of polyimide grafted aramid fiber. The POSS-grafted polyurethane acrylate is prepared by the following steps: Step A1: Stir γ-aminopropyltriethoxysilane, chloropropanol, triethylamine and toluene, react, filter, collect the liquid by distillation, add the liquid to a flask, add trifluoromethanesulfonic acid and deionized water, stir, distill under reduced pressure, wash, filter and dry to obtain hydroxyl POSS; Step A2: HydroxyPOSS, S-benzyloxycarbonyl-L-cysteine, 4-dimethylaminopyridine and dichloromethane were stirred and sonicated in an ice bath. N,N'-diisopropylcarbodiimide was added to react. The ice bath was removed, the mixture was stirred, separated and purified, and dried to obtain the first intermediate. Step A3: Add the first intermediate and dichloromethane to a flask, purge with nitrogen, add n-octyl mercaptan, 1,8-diazabicyclo[5.4.0]undec-7-ene, aluminum chloride and hexafluoroisopropanol to react, quench the reaction, extract by liquid-liquid extraction, collect the organic phase, dry it, filter and concentrate it, separate and purify it, dry it and add it to a flask, add dichloromethane and stir, add triethylamine and stir, add p-hydroxybenzoyl chloride and stir, separate and purify it, dry it to obtain p-hydroxybenzoylamino-POSS; Step A5: Polyethylene glycol, 2,2-bis(4-phenylisocyanate)hexafluoropropane and N,N-dimethylformamide are added to a flask, nitrogen gas is introduced, prepolymerization is carried out, dibutyltin dilaurate and diethylene glycol are added to react after cooling, p-hydroxybenzoylamino-POSS is added to react after cooling, and dried to obtain POSS-grafted polyurethane acrylate.

2. The fiber-reinforced and toughened flexible resin for printing plates according to claim 1, characterized in that, The ratio of γ-aminopropyltriethoxysilane, chloropropanol, triethylamine, toluene, trifluoromethanesulfonic acid and deionized water used in step A1 is 18-36g: 9.4-18.8g: 10-20g: 92-184mL: 4.5-9g: 60-120mL.

3. The fiber-reinforced and toughened flexible resin for printing plates according to claim 1, characterized in that, The ratio of hydroxyPOSS, S-benzyloxycarbonyl-L-cysteine, 4-dimethylaminopyridine, dichloromethane, and N,N'-diisopropylcarbodiimide used in step A2 is 1.09-2.18 mmol: 1.09-2.18 mmol: 0.47-0.94 mmol: 10-20 mL: 1.1-2.2 mmol.

4. The fiber-reinforced and toughened flexible resin for printing plates according to claim 1, characterized in that, In step A3, the ratio of the first intermediate, dichloromethane, n-octylthiol, 1,8-diazabicyclo[5.4.0]undec-7-ene, aluminum chloride, hexafluoroisopropanol, dichloromethane, triethylamine, and p-hydroxybenzoyl chloride is 1.34-2.68 mmol: 10-20 mL: 1.5-3 mmol: 0.62-1.24mmol: 0.5-1mmol: 10-20mL: 10-20mL: 1-2mmol: 1-2mmol.

5. The fiber-reinforced and toughened flexible resin for printing plates according to claim 1, characterized in that, In step A4, the ratio of polyethylene glycol, 2,2-bis(4-phenylisocyanate)hexafluoropropane, N,N-dimethylformamide, dibutyltin dilaurate, diethylene glycol, and p-hydroxybenzoylamino-POSS is 10-20g: 0.02-0.04mol: 120-240mL: 0.155-0.31g: 0.005-0.01mol: 0.02-0.04mol; the polyethylene glycol is PEG2000.

6. The fiber-reinforced and toughened flexible resin for printing plates according to claim 1, characterized in that, The POSS-grafted polyurethane acrylate is prepared by the following steps: Step B1: Add chopped aramid fibers, potassium hydroxide solution, tetrabutylammonium bromide and dimethyl sulfoxide to a flask and stir. Add acetone and stir. Vacuum filter and dry to obtain pretreated aramid fibers. Step B2: Add 3-aminopropyltrimethoxysilane and anhydrous ethanol to a beaker and stir. Adjust the pH of the tannic acid solution to 8.5 with tris(hydroxymethyl)aminomethane and add it to the beaker and stir. Add the pretreated aramid fiber for impregnation and dry to obtain modified aramid fiber. Step B3: Add diaminodiphenyl ether and N,N-dimethylacetamide to a flask and stir. Purge with nitrogen gas and place in an ice bath. Add pyromellitic dianhydride and stir. Add triethanolamine and stir. Heat in a water bath and add methanol. Transfer to a beaker and add modified aramid fiber. Stir to react. Wash and dry to obtain polyimide-grafted aramid fiber.

7. The fiber-reinforced and toughened flexible resin for printing plates according to claim 6, characterized in that, In step B1, the ratio of the amount of chopped aramid fiber, potassium hydroxide solution, tetrabutylammonium bromide, dimethyl sulfoxide, and acetone is 1.5-3g: 4.5-9g: 0.15-0.3g: 150-300mL: 75-150mL; the mass fraction of the potassium hydroxide solution is 50%.

8. The fiber-reinforced and toughened flexible resin for printing plates according to claim 6, characterized in that, In step B2, the ratio of 3-aminopropyltrimethoxysilane, anhydrous ethanol, tannic acid solution, and pretreated aramid fiber is 2-4g: 20-40mL: 20-40mL: 5-10g; the concentration of the tannic acid solution is 2g / L.

9. The fiber-reinforced and toughened flexible resin for printing plates according to claim 6, characterized in that, The ratio of diaminodiphenyl ether, N,N-dimethylacetamide, pyromellitic dianhydride, triethanolamine, methanol, and modified aramid fiber in step B3 is 0.025-0.05 mol: 100-200 mL: 0.025-0.05 mol: 5.0595-10.119 g: 300-600 mL: 2-4 g.

10. A method for preparing a fiber-reinforced and toughened flexible resin for printing plates, characterized in that, The method for preparing the fiber-reinforced, toughened, flexible resin for printing plates as described in any one of claims 1-9 comprises the following steps: Step 1: Weigh out 45-50 parts of POSS grafted polyurethane acrylate and 15-20 parts of polyimide grafted aramid fiber according to the weight ratio, and set aside. Step 2: Mix POSS grafted polyurethane acrylate and polyimide grafted aramid fiber to obtain fiber-reinforced and toughened flexible resin for printing plates.

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