Waterproof and yellowing-resistant polyurethane shoe leather and its processing technology

Abstract

The present invention relates to the technical field of polyurethane shoe leather, specifically to a waterproof and yellowing-resistant polyurethane shoe leather and its processing technology. The scheme adopts dry veneer to obtain the polyurethane shoe leather, firstly, the polyurethane surface layer slurry is coated on the surface of release paper, and then baked after coating on the surface of release paper, and then the adhesive is coated on the surface of the semi-cured surface layer, and the surface layer is bonded to the ultrafine fiber base cloth by using the adhesive, and the polyurethane shoe leather is obtained after aging and compounding. On the basis of this process, the scheme uses epoxy resin and acrylate to modify the polyurethane emulsion to obtain an interpenetrating network of epoxy resin, acrylate and polyurethane, and uses the composite emulsion as the polyurethane surface layer slurry, and the tensile strength, tear strength and water resistance of the polyurethane surface layer can be greatly improved. The prepared polyurethane shoe leather not only has excellent water resistance, but also has excellent mechanical properties of the surface layer resin, yellowing resistance, high flame retardancy, and high practicality.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane shoe leather, in particular to waterproof and yellowing-resistant polyurethane shoe leather and a processing technology thereof. Background Art

[0002] In the prior art, leather is generally divided into natural leather and synthetic leather. Natural leather is made from animal hides and skins and is processed through a series of physical and chemical processes. It has good physical and mechanical properties and exquisite appearance. However, with the rapid development of the economy, natural leather resources are limited and can no longer meet our consumer needs. Therefore, synthetic leather is used more and more widely.

[0003] After a long period of research and development and experiments, the researchers compounded polyurethane resin with base fabric to prepare polyurethane synthetic leather that looks similar to natural leather, which is also the most commonly used shoe leather raw material. However, the yellowing resistance of the shoe leather developed currently cannot last long, and its flame retardancy is poor, which cannot actually meet our needs.

[0004] Based on this situation, we disclose a waterproof and yellowing-resistant polyurethane shoe leather and its processing technology to solve this technical problem. Summary of the invention

[0005] The object of the present invention is to provide a waterproof and yellowing-resistant polyurethane shoe leather and a processing technology thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A processing technology for waterproof and yellowing-resistant polyurethane shoe leather comprises the following steps:

[0008] (1) vacuum dehydrating polytetrahydrofuran diol, cooling to 60-65° C., adding isophorone diisocyanate and dibutyltin dilaurate, keeping the temperature at 90-95° C. for 2-3 hours, adding a chain extender, and continuing the reaction for 1-2 hours to obtain a polyurethane prepolymer; adding 1,4-butanediol, epoxy resin, hydroxyethyl acrylate and ultraviolet absorber modified flame retardant monomer to the polyurethane prepolymer, continuing the reaction for 1-1.5 hours, cooling to 40° C., standing for 0.5-1 hour, adding triethylamine for neutralization for 30 minutes, adding deionized water for emulsification for 30-40 minutes, and obtaining an epoxy resin modified polyurethane emulsion;

[0009] Mixing acrylate monomer and potassium persulfate, adding epoxy resin modified polyurethane emulsion, stirring and reacting at 80-85° C. for 3-4 hours to obtain a surface layer emulsion; the acrylate monomer includes methyl methacrylate, ethyl acrylate and ultraviolet absorber modified flame retardant monomer;

[0010] Mix the surface layer emulsion, defoamer, leveling agent and thickener, stir evenly to obtain a surface layer slurry;

[0011] (2) coating the surface slurry prepared in step (1) onto the surface of release paper, drying at 110-120° C. for 2-3 min, coating the surface with an adhesive, and baking at 100-105° C. for 1-2 min. After baking, laminating one side of the adhesive with the microfiber base cloth, transferring to 120-130° C. for aging for 8-10 min, cooling, and removing the release paper to obtain the shoe leather.

[0012] A more optimized solution is that in step (1), the molar ratio of the polytetrahydrofuran diol, isophorone diisocyanate, chain extender and 1,4-butanediol is 1:(5-6):2:1, the amount of the epoxy resin is 3-4wt% of the total amount of the polytetrahydrofuran diol and isophorone diisocyanate; the amount of the dibutyltin dilaurate is 0.5-1wt% of the total amount of the polytetrahydrofuran diol and isophorone diisocyanate; the chain extender includes dimethylol propionic acid and dimethylol butyric acid, and the molar ratio of the dimethylol propionic acid and dimethylol butyric acid is 1:1; the amount of the hydroxyethyl acrylate is 0.3-0.5wt% of the total amount of the polytetrahydrofuran diol and isophorone diisocyanate; and the amount of the ultraviolet absorber modified flame retardant monomer is 1.5-2wt% of the total amount of the polytetrahydrofuran diol and isophorone diisocyanate.

[0013] In a more optimized solution, in step (1), the mass ratio of methyl methacrylate, ultraviolet absorber modified flame retardant monomer and ethyl acrylate is 5:3:1; the amount of the acrylate monomer is 3-4wt% of the total amount of polytetramethylene glycol, isophorone diisocyanate and chain extender; and the amount of potassium persulfate is 0.3-0.5wt% of the acrylate monomer.

[0014] In a more optimized solution, in step (1), the contents of each component by mass are: 100-105 parts of surface layer emulsion, 0.3-0.5 parts of defoaming agent, 0.5-1 parts of leveling agent, and 1-1.5 parts of thickener.

[0015] In a more optimized solution, in step (1), the preparation steps of the ultraviolet absorber-modified flame retardant monomer are:

[0016] S1: Mix a UV absorber and tetrahydrofuran, and stir until dissolved to obtain a UV absorber solution;

[0017] Mix hexachlorocyclotriphosphazene and tetrahydrofuran, add triethylamine and ultraviolet absorber solution at 75-85°C, reflux for 20-24h, remove tetrahydrofuran by rotary evaporation, collect the product, wash and dry to obtain an intermediate;

[0018] S2: Take the intermediate, hydroxyethyl acrylate, anhydrous potassium carbonate and tetrahydrofuran, mix them, stir them evenly under nitrogen environment, heat them to 60-65°C, reflux them for 42-46 hours, cool them to room temperature after the reaction, collect the products, wash and dry them to obtain functional monomer A;

[0019] S3: Mix 2,3-epoxy-1-propanol and tetrahydrofuran, and stir evenly to obtain a 2,3-epoxy-1-propanol solution;

[0020] The intermediate, tetrahydrofuran and sodium hydride are mixed, stirred evenly under nitrogen atmosphere, 2,3-epoxy-1-propanol solution is added, reacted at 30-35° C. for 3-4 hours, tetrahydrofuran is removed by rotary evaporation after the reaction, the product is collected, washed and dried to obtain functional monomer B;

[0021] S4: mixing p-hydroxybiphenol and tetrahydrofuran, stirring evenly to obtain a p-hydroxybiphenol solution;

[0022] Take functional monomer A and tetrahydrofuran and mix them, add p-hydroxybiphenol solution in a -20°C ice water bath, react for 6 to 8 hours, then add functional monomer B, raise the temperature to 20 to 25°C, continue to react for 4 to 5 hours, collect the product by filtration, wash and dry to obtain a flame retardant monomer.

[0023] In a more optimized scheme, in step S1, the concentration of the ultraviolet absorber solution is 0.8-1 mol / L; the ultraviolet absorber is a compound of any one or more of p-hydroxyacetophenone, 4-hydroxybenzophenone, and 2,4-dihydroxybenzophenone; and the molar ratio of the hexachlorocyclotriphosphazene to the ultraviolet absorber is 1:(2-2.2).

[0024] In a more optimized scheme, in step S2, the molar ratio of the intermediate to hydroxyethyl acrylate is 1:(2-2.3);

[0025] In step S3, the concentration of the 2,3-epoxy-1-propanol solution is 0.6-0.8 mol / L; the molar ratio of the intermediate to 2,3-epoxy-1-propanol is 1:(2-2.2).

[0026] According to a more optimized solution, in step S4, the concentration of the p-hydroxybiphenol solution is 0.5-0.6 mol / L; and the molar ratio of the functional monomer A, p-hydroxybiphenol, and functional monomer B is 1:(1-1.1):1.

[0027] A more optimized solution is a polyurethane shoe leather processed according to the processing technology of the waterproof and yellowing-resistant polyurethane shoe leather described in any one of the above.

[0028] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0029] The invention discloses a waterproof and yellowing-resistant polyurethane shoe leather and a processing technology thereof. The scheme adopts a dry veneer to obtain the leather. First, a polyurethane surface layer slurry is coated on the surface of a release paper. The release paper can be a flat paper or an embossed paper. The specific selection can be based on actual process requirements. After being coated on the surface of the release paper, it is baked. An adhesive is coated on the surface of the semi-cured surface layer. The adhesive can be a polyurethane adhesive. The surface layer is laminated with an ultrafine fiber base cloth by using the adhesive. After ripening and compounding, the polyurethane shoe leather is obtained. Based on the process, the scheme uses epoxy resin and acrylate to modify the polyurethane emulsion to obtain an interpenetrating network of epoxy resin, acrylate and polyurethane. The composite emulsion is used as the polyurethane surface layer slurry. The tensile strength, tear strength and water resistance of the polyurethane surface layer can be greatly improved.

[0030] Furthermore, in order to improve the yellowing resistance of polyurethane shoe leather, the solution introduces ultraviolet absorbers into the polyurethane surface slurry to improve its resistance to ultraviolet aging and improve its yellowing resistance. Existing ultraviolet absorbers generally select salicylates, benzophenones, benzotriazoles, triazines, etc., but pure ultraviolet absorbers have poor compatibility with polyurethane slurry. During use, ultraviolet absorbers are easy to migrate, resulting in a decrease or failure of their ultraviolet absorption protection ability, and the yellowing resistance of shoe leather also decreases accordingly; at the same time, in the actual processing of polyurethane shoe leather, enterprises also have high requirements for the flame retardant properties of polyurethane shoe leather. Therefore, based on the two technical requirements of "improvement of ultraviolet absorber anti-migration performance" and "improvement of flame retardant performance", the R&D personnel adjusted the solution as follows:

[0031] (1) Hexachlorocyclotriphosphazene is selected as a flame retardant component, and its surface active functional group P-Cl is used to react with -OH on the surface of the ultraviolet absorber to graft the ultraviolet absorber with the flame retardant component to obtain an intermediate with flame retardancy. The reason for this step is that: on the one hand, in order to reduce the migration of the ultraviolet absorber, the ultraviolet absorber is surface grafted and active groups are introduced to make it participate in the system reaction, thereby improving its migration resistance. Hexachlorocyclotriphosphazene contains multiple active functional groups. In order to achieve both yellowing resistance and flame retardancy improvement at the same time, the grafting reaction of hexachlorocyclotriphosphazene with the ultraviolet absorber can better realize the concept, and no additional addition is required during the processing of the scheme. Flame retardant, simplifying the process; on the other hand, since the system of the surface slurry is an epoxy resin, acrylate, and polyurethane composite system, in order to better ensure the compatibility of the ultraviolet absorber in the system, on the basis of grafting the ultraviolet absorber, the scheme uses multiple active functional groups of hexachlorocyclotriphosphazene to introduce epoxy groups and C=C to participate in the reaction of each step. While improving the compatibility, it can also increase the cross-linking density of the emulsion, thereby further improving the comprehensive performance of the polyurethane surface layer. It is also based on the above reasons that the scheme here limits "the molar ratio of the hexachlorocyclotriphosphazene to the ultraviolet absorber to 1: (2 to 2.2)" to ensure the grafting of subsequent reaction functional groups.

[0032] (2) The intermediate is subjected to a grafting reaction with hydroxyethyl acrylate, and the remaining active functional group P-Cl on the surface of the intermediate is used to react with the -OH on the surface of hydroxyethyl acrylate to generate a functional monomer A, and a C=C double bond is introduced to participate in the polymerization of the acrylate monomer.

[0033] The intermediate is grafted with 2,3-epoxy-1-propanol, and the remaining active functional group P-Cl on the surface of the intermediate is reacted with -OH on the surface of 2,3-epoxy-1-propanol to generate a functional monomer B. The functional monomer A and the functional monomer B are bridged by p-hydroxybiphenol to obtain a flame retardant monomer with C=C introduced at one end and an epoxy group introduced at the other end and grafted with a UV absorber.

[0034] In order to ensure the smooth implementation of the above scheme, the scheme also stipulates that "the molar ratio of the intermediate and 2,3-epoxy-1-propanol is 1:(2~2.2)" and "the molar ratio of the intermediate and hydroxyethyl acrylate is 1:(2~2.3)". Some hydroxyl groups can still remain in the hexachlorocyclotriphosphazene at both ends of the monomer and participate in the reaction during the polyurethane grafting reaction, so that the flame retardant monomer can be better compatible with the polyurethane surface slurry system, improve the cross-linking density of the surface slurry, and thus improve the comprehensive performance of the polyurethane surface layer.

[0035] The present invention discloses a waterproof and yellowing-resistant polyurethane shoe leather and a processing technology thereof. The prepared polyurethane shoe leather not only has excellent water resistance, but also has excellent mechanical properties of the surface resin, is yellowing-resistant, has high flame retardancy, and has high practicality. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the following examples, the preparation steps of the intermediate are as follows: 0.21 mol of 2,4-dihydroxybenzophenone and tetrahydrofuran are mixed, and stirred at 85° C. until dissolved to obtain a 2,4-dihydroxybenzophenone solution; the concentration of the 2,4-dihydroxybenzophenone solution is 1 mol / L.

[0038] Take 0.1 mol of hexachlorocyclotriphosphazene and 300 mL of tetrahydrofuran, mix them, stir for 25 minutes, add 0.12 mol of triethylamine and 2,4-dihydroxybenzophenone solution at 80°C, reflux for 22 hours, remove tetrahydrofuran by rotary evaporation, collect the product, wash and dry it to obtain an intermediate.

[0039] In the following examples, the leveling agent is BYK333, the defoaming agent is BYK-A 535, both purchased from BYK Chemicals; the thickener is TR-8W, purchased from Guangzhou Meicheng New Material Technology Co., Ltd.; the release paper is commercially available embossed paper; the binder is a solvent-free two-component polyurethane adhesive resin AL-3051A / AL-5040B, purchased from Hefei Amway Polyurethane New Materials Co., Ltd.; the microfiber base cloth is purchased from Yantai Wanhua Synthetic Leather Group Co., Ltd.; 2,4-dihydroxybenzophenone, tetrahydrofuran, hexachlorocyclotriphosphazene, and triethylamine are all purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; hydroxyethyl acrylate (H810915), anhydrous potassium carbonate, 2,3-epoxy-1-propanol (G823277 ), sodium hydride, p-hydroxybiphenol (D806796), dibutyltin dilaurate, methyl methacrylate, and ethyl acrylate were all purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; polytetramethylene glycol was PTMG-1000 with a hydroxyl value of 107-118 mgKOH / g, purchased from BASF, Germany; isophorone diisocyanate (CP) was purchased from Bayer, Germany; dimethylolpropionic acid and dimethylolbutyric acid were both purchased from Aldrich; 1,4-butanediol was purchased from Tianjin Guangfu Fine Chemical Research Institute; the epoxy resin was epoxy resin E-51, purchased from Nantong Xingchen Material Synthesis Co., Ltd.

[0040] Embodiment 1:

[0041] A processing technology for waterproof and yellowing-resistant polyurethane shoe leather comprises the following steps:

[0042] (1) S1: 0.1 mol of the intermediate, 0.23 mol of hydroxyethyl acrylate, 0.85 mol of anhydrous potassium carbonate and 500 mL of tetrahydrofuran were mixed, stirred evenly under nitrogen atmosphere, heated to 60° C., and refluxed for 46 h. After the reaction was completed, the mixture was cooled to room temperature, the product was collected, washed and dried to obtain functional monomer A.

[0043] S2: 0.22 mol of 2,3-epoxy-1-propanol and tetrahydrofuran were mixed and stirred to obtain a 2,3-epoxy-1-propanol solution; the concentration of the 2,3-epoxy-1-propanol solution was 0.6 mol / L.

[0044] Take 0.1 mol of the intermediate, 300 mL of tetrahydrofuran and 0.1 mol of sodium hydride, mix them, stir them evenly under a nitrogen environment, add 2,3-epoxy-1-propanol solution, react at 30°C for 4 hours, remove tetrahydrofuran by rotary evaporation after the reaction, collect the product, wash and dry it to obtain functional monomer B.

[0045] S3: 0.11 mol of p-hydroxybiphenol and tetrahydrofuran are mixed and stirred evenly to obtain a p-hydroxybiphenol solution; the concentration of the p-hydroxybiphenol solution is 0.5 mol / L.

[0046] Take 0.1 mol of functional monomer A and 300 mL of tetrahydrofuran, mix them, stir for 20 minutes, add p-hydroxybiphenol solution in a -20°C ice water bath, react for 6 hours, then add 0.1 mol of functional monomer B, raise the temperature to 20°C, continue to react for 5 hours, filter and collect the product, wash and dry to obtain a flame retardant monomer.

[0047] (2) Take 0.2 mol of polytetrahydrofuran diol, vacuum dehydrate at 110° C. for 2 h, cool to 60° C., add 1.2 mol of isophorone diisocyanate and dibutyltin dilaurate, keep warm at 90° C. for reaction for 3 h, then add 0.4 mol of chain extender, continue to react for 1 h, and obtain a polyurethane prepolymer; add 0.2 mol of 1,4-butanediol, epoxy resin, hydroxyethyl acrylate and ultraviolet absorber modified flame retardant monomer to the polyurethane prepolymer, continue to react for 1 h, cool to 40° C., stand for 0.5 h, add triethylamine for neutralization for 30 min, add deionized water for emulsification for 30 min, and obtain an epoxy resin modified polyurethane emulsion with a solid content of 50%.

[0048] The epoxy resin is used in an amount of 3wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate; the dibutyltin dilaurate is used in an amount of 0.8wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate; the chain extender includes dimethylol propionic acid and dimethylol butyric acid, and the molar ratio of dimethylol propionic acid to dimethylol butyric acid is 1:1; the hydroxyethyl acrylate is used in an amount of 0.5wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate. The ultraviolet absorber modified flame retardant monomer is used in an amount of 1.5wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate.

[0049] Take an acrylate monomer and potassium persulfate and mix them, add epoxy resin modified polyurethane emulsion, stir and react at 80°C for 3 hours to obtain a surface layer emulsion; the acrylate monomer includes methyl methacrylate, ethyl acrylate and ultraviolet absorber modified flame retardant monomer; the mass ratio of the methyl methacrylate, ultraviolet absorber modified flame retardant monomer and ethyl acrylate is 5:3:1; the amount of the acrylate monomer is 4wt% of the total amount of polytetramethylene glycol, isophorone diisocyanate and chain extender; the amount of potassium persulfate is 0.5wt% of the acrylate monomer.

[0050] Take 100g of the surface layer emulsion, 0.5g of the defoamer, 1g of the leveling agent and 1.5g of the thickener, mix them, stir evenly, and obtain the surface layer slurry.

[0051] (3) coating the surface slurry prepared in step (2) onto the surface of the release paper with a coating thickness of 300 μm, drying at 110° C. for 3 min, coating the surface with an adhesive, and baking at 100° C. for 2 min. After baking, laminating one side of the adhesive with the microfiber base cloth, transferring to 120° C. for aging for 10 min, cooling, and removing the release paper to obtain the shoe leather.

[0052] Embodiment 2:

[0053] A processing technology for waterproof and yellowing-resistant polyurethane shoe leather comprises the following steps:

[0054] (1) S1: 0.1 mol of the intermediate, 0.23 mol of hydroxyethyl acrylate, 0.85 mol of anhydrous potassium carbonate and 500 mL of tetrahydrofuran were mixed, stirred evenly under nitrogen atmosphere, heated to 65° C., and refluxed for 45 h. After the reaction was completed, the mixture was cooled to room temperature, the product was collected, washed and dried to obtain functional monomer A.

[0055] S2: 0.22 mol of 2,3-epoxy-1-propanol and tetrahydrofuran were mixed and stirred to obtain a 2,3-epoxy-1-propanol solution; the concentration of the 2,3-epoxy-1-propanol solution was 0.6 mol / L.

[0056] Take 0.1 mol of the intermediate, 300 mL of tetrahydrofuran and 0.1 mol of sodium hydride, mix them, stir them evenly under a nitrogen environment, add 2,3-epoxy-1-propanol solution, react at 35°C for 3.5 hours, remove tetrahydrofuran by rotary evaporation after the reaction, collect the product, wash and dry it to obtain functional monomer B.

[0057] S3: 0.11 mol of p-hydroxybiphenol and tetrahydrofuran are mixed and stirred evenly to obtain a p-hydroxybiphenol solution; the concentration of the p-hydroxybiphenol solution is 0.5 mol / L.

[0058] Take 0.1 mol of functional monomer A and 300 mL of tetrahydrofuran, mix, stir for 25 minutes, add p-hydroxybiphenol solution in a -20°C ice water bath, react for 7 hours, then add 0.1 mol of functional monomer B, raise the temperature to 25°C, continue to react for 4.5 hours, filter and collect the product, wash and dry to obtain a flame retardant monomer.

[0059] (2) Take 0.2 mol of polytetrahydrofuran diol, vacuum dehydrate at 110° C. for 2 h, cool to 65° C., add 1.2 mol of isophorone diisocyanate and dibutyltin dilaurate, keep warm at 95° C. for reaction for 2.5 h, then add 0.4 mol of chain extender, continue to react for 1.5 h, and obtain a polyurethane prepolymer; add 0.2 mol of 1,4-butanediol, epoxy resin, hydroxyethyl acrylate and ultraviolet absorber modified flame retardant monomer to the polyurethane prepolymer, continue to react for 1.5 h, cool to 40° C., stand for 0.5 h, add triethylamine for neutralization for 30 min, add deionized water for emulsification for 35 min, and obtain an epoxy resin modified polyurethane emulsion with a solid content of 50%.

[0060] The epoxy resin is used in an amount of 3wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate; the dibutyltin dilaurate is used in an amount of 0.8wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate; the chain extender includes dimethylol propionic acid and dimethylol butyric acid, and the molar ratio of dimethylol propionic acid to dimethylol butyric acid is 1:1; the hydroxyethyl acrylate is used in an amount of 0.5wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate. The ultraviolet absorber modified flame retardant monomer is used in an amount of 1.5wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate.

[0061] Take an acrylate monomer and potassium persulfate, mix them, add epoxy resin modified polyurethane emulsion, stir and react at 85°C for 3.5 hours to obtain a surface layer emulsion; the acrylate monomer includes methyl methacrylate, ethyl acrylate and ultraviolet absorber modified flame retardant monomer; the mass ratio of the methyl methacrylate, ultraviolet absorber modified flame retardant monomer and ethyl acrylate is 5:3:1; the amount of the acrylate monomer is 4wt% of the total amount of polytetramethylene glycol, isophorone diisocyanate and chain extender; the amount of potassium persulfate is 0.5wt% of the acrylate monomer.

[0062] Take 100g of the surface layer emulsion, 0.5g of the defoamer, 1g of the leveling agent and 1.5g of the thickener, mix them, stir evenly, and obtain the surface layer slurry.

[0063] (3) coating the surface slurry prepared in step (2) onto the surface of the release paper with a coating thickness of 300 μm, drying at 115° C. for 3 min, coating the surface with an adhesive, and baking at 105° C. for 2 min. After baking, laminating one side of the adhesive with the microfiber base cloth, transferring to 125° C. for aging for 9 min, cooling, and removing the release paper to obtain the shoe leather.

[0064] Embodiment 3:

[0065] A processing technology for waterproof and yellowing-resistant polyurethane shoe leather comprises the following steps:

[0066] (1) S1: 0.1 mol of the intermediate, 0.23 mol of hydroxyethyl acrylate, 0.85 mol of anhydrous potassium carbonate and 500 mL of tetrahydrofuran were mixed, stirred evenly under nitrogen atmosphere, heated to 65° C., and refluxed for 42 h. After the reaction was completed, the mixture was cooled to room temperature, the product was collected, washed and dried to obtain functional monomer A.

[0067] S2: 0.22 mol of 2,3-epoxy-1-propanol and tetrahydrofuran were mixed and stirred to obtain a 2,3-epoxy-1-propanol solution; the concentration of the 2,3-epoxy-1-propanol solution was 0.6 mol / L.

[0068] Take 0.1 mol of the intermediate, 300 mL of tetrahydrofuran and 0.1 mol of sodium hydride, mix them, stir them evenly under a nitrogen environment, add 2,3-epoxy-1-propanol solution, react at 35°C for 3 hours, remove tetrahydrofuran by rotary evaporation after the reaction, collect the product, wash and dry it to obtain functional monomer B.

[0069] S3: 0.11 mol of p-hydroxybiphenol and tetrahydrofuran are mixed and stirred evenly to obtain a p-hydroxybiphenol solution; the concentration of the p-hydroxybiphenol solution is 0.5 mol / L.

[0070] Take 0.1 mol of functional monomer A and 300 mL of tetrahydrofuran, mix them, stir for 30 minutes, add p-hydroxybiphenol solution in a -20°C ice water bath, react for 8 hours, then add 0.1 mol of functional monomer B, raise the temperature to 25°C, continue to react for 4 hours, filter and collect the product, wash and dry to obtain a flame retardant monomer.

[0071] (2) Take 0.2 mol of polytetrahydrofuran diol, vacuum dehydrate at 110° C. for 2 h, cool to 65° C., add 1.2 mol of isophorone diisocyanate and dibutyltin dilaurate, keep warm at 95° C. for reaction for 2 h, then add 0.4 mol of chain extender, continue to react for 2 h, and obtain a polyurethane prepolymer; add 0.2 mol of 1,4-butanediol, epoxy resin, hydroxyethyl acrylate and ultraviolet absorber modified flame retardant monomer to the polyurethane prepolymer, continue to react for 1.5 h, cool to 40° C., stand for 0.5 h, add triethylamine for neutralization for 30 min, add deionized water for emulsification for 40 min, and obtain an epoxy resin modified polyurethane emulsion with a solid content of 50%.

[0072] The epoxy resin is used in an amount of 3wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate; the dibutyltin dilaurate is used in an amount of 0.8wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate; the chain extender includes dimethylol propionic acid and dimethylol butyric acid, and the molar ratio of dimethylol propionic acid to dimethylol butyric acid is 1:1; the hydroxyethyl acrylate is used in an amount of 0.5wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate. The ultraviolet absorber modified flame retardant monomer is used in an amount of 1.5wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate.

[0073] Take acrylate monomer and potassium persulfate and mix them, add epoxy resin modified polyurethane emulsion, stir and react at 85°C for 3 hours to obtain a surface layer emulsion; the acrylate monomer includes methyl methacrylate, ethyl acrylate and ultraviolet absorber modified flame retardant monomer; the mass ratio of methyl methacrylate, ultraviolet absorber modified flame retardant monomer and ethyl acrylate is 5:3:1; the amount of the acrylate monomer is 4wt% of the total amount of polytetramethylene glycol, isophorone diisocyanate and chain extender; the amount of potassium persulfate is 0.5wt% of the acrylate monomer.

[0074] Take 100g of the surface layer emulsion, 0.5g of the defoamer, 1g of the leveling agent and 1.5g of the thickener, mix them, stir evenly, and obtain the surface layer slurry.

[0075] (3) coating the surface slurry prepared in step (2) onto the surface of the release paper with a coating thickness of 300 μm, drying at 120° C. for 2 min, coating the surface with an adhesive, and baking at 105° C. for 1 min. After baking, laminating one side of the adhesive with the microfiber base cloth, transferring to 130° C. for aging for 8 min, cooling, and removing the release paper to obtain the shoe leather.

[0076] Comparative Example 1: Example 3 was used as a control group. In Comparative Example 1, the functional monomer A and the functional monomer B were not bridged, and the other steps remained unchanged.

[0077] A processing technology for waterproof and yellowing-resistant polyurethane shoe leather comprises the following steps:

[0078] (1) S1: 0.1 mol of the intermediate, 0.23 mol of hydroxyethyl acrylate, 0.85 mol of anhydrous potassium carbonate and 500 mL of tetrahydrofuran were mixed, stirred evenly under nitrogen atmosphere, heated to 65° C., and refluxed for 42 h. After the reaction was completed, the mixture was cooled to room temperature, the product was collected, washed and dried to obtain functional monomer A.

[0079] S2: 0.22 mol of 2,3-epoxy-1-propanol and tetrahydrofuran were mixed and stirred to obtain a 2,3-epoxy-1-propanol solution; the concentration of the 2,3-epoxy-1-propanol solution was 0.6 mol / L.

[0080] Take 0.1 mol of the intermediate, 300 mL of tetrahydrofuran and 0.1 mol of sodium hydride, mix them, stir them evenly under a nitrogen environment, add 2,3-epoxy-1-propanol solution, react at 35°C for 3 hours, remove tetrahydrofuran by rotary evaporation after the reaction, collect the product, wash and dry it to obtain functional monomer B.

[0081] (2) Take 0.2 mol of polytetrahydrofuran diol, vacuum dehydrate at 110° C. for 2 h, cool to 65° C., add 1.2 mol of isophorone diisocyanate and dibutyltin dilaurate, keep warm and react at 95° C. for 2 h, then add 0.4 mol of chain extender and continue to react for 2 h to obtain a polyurethane prepolymer; add 0.2 mol of 1,4-butanediol, epoxy resin, hydroxyethyl acrylate and functional monomer B to the polyurethane prepolymer, continue to react for 1.5 h, cool to 40° C., stand for 0.5 h, add triethylamine for neutralization for 30 min, add deionized water for emulsification for 40 min, and obtain an epoxy resin modified polyurethane emulsion with a solid content of 50%.

[0082] The epoxy resin is used in an amount of 3wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate; the dibutyltin dilaurate is used in an amount of 0.8wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate; the chain extender includes dimethylol propionic acid and dimethylol butyric acid, and the molar ratio of dimethylol propionic acid to dimethylol butyric acid is 1:1; the functional monomer B is used in an amount of 0.5wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate. The hydroxyethyl acrylate is used in an amount of 1.5wt% of the total amount of polytetrahydrofuran diol and isophorone diisocyanate.

[0083] Take an acrylate monomer and potassium persulfate and mix them, add epoxy resin modified polyurethane emulsion, stir and react at 85°C for 3 hours to obtain a surface layer emulsion; the acrylate monomer includes methyl methacrylate, ethyl acrylate and functional monomer A; the mass ratio of methyl methacrylate, functional monomer A and ethyl acrylate is 5:3:1; the amount of the acrylate monomer is 4wt% of the total amount of polytetramethylene glycol, isophorone diisocyanate and chain extender; the amount of potassium persulfate is 0.5wt% of the acrylate monomer.

[0084] Take 100g of the surface layer emulsion, 0.5g of the defoamer, 1g of the leveling agent and 1.5g of the thickener, mix them, stir evenly, and obtain the surface layer slurry.

[0085] (3) coating the surface slurry prepared in step (2) onto the surface of the release paper with a coating thickness of 300 μm, drying at 120° C. for 2 min, coating the surface with an adhesive, and baking at 105° C. for 1 min. After baking, laminating one side of the adhesive with the microfiber base cloth, transferring to 130° C. for aging for 8 min, cooling, and removing the release paper to obtain the shoe leather.

[0086] Comparative Example 2: Example 3 was used as the control group. In Comparative Example 2, only an ultraviolet absorber was added without monomer graft polymerization, and the remaining steps remained unchanged.

[0087] A processing technology for waterproof and yellowing-resistant polyurethane shoe leather comprises the following steps:

[0088] (1) 0.2 mol of polytetrahydrofuran diol was taken, vacuum dehydrated at 110° C. for 2 h, cooled to 65° C., 1.2 mol of isophorone diisocyanate and dibutyltin dilaurate were added, and the mixture was kept warm for reaction at 95° C. for 2 h, and 0.4 mol of chain extender was added, and the reaction was continued for 2 h to obtain a polyurethane prepolymer; 0.2 mol of 1,4-butanediol, epoxy resin and hydroxyethyl acrylate were added to the polyurethane prepolymer, and the reaction was continued for 1.5 h, cooled to 40° C., and allowed to stand for 0.5 h, triethylamine was added for neutralization for 30 min, and deionized water was added for emulsification for 40 min to obtain an epoxy resin modified polyurethane emulsion with a solid content of 50%.

[0089] The epoxy resin is used in an amount of 3wt% of the total amount of polytetramethylene glycol and isophorone diisocyanate; the dibutyltin dilaurate is used in an amount of 0.8wt% of the total amount of polytetramethylene glycol and isophorone diisocyanate; the chain extender comprises dimethylol propionic acid and dimethylol butyric acid, and the molar ratio of dimethylol propionic acid to dimethylol butyric acid is 1:1; the hydroxyethyl acrylate is used in an amount of 1.5wt% of the total amount of polytetramethylene glycol and isophorone diisocyanate.

[0090] Take acrylate monomer and potassium persulfate and mix them, add epoxy resin modified polyurethane emulsion, stir and react at 85°C for 3 hours to obtain a surface layer emulsion; the acrylate monomer includes methyl methacrylate and ethyl acrylate; the mass ratio of methyl methacrylate to ethyl acrylate is 5:1; the amount of the acrylate monomer is 4wt% of the total amount of polytetramethylene glycol, isophorone diisocyanate and chain extender; the amount of potassium persulfate is 0.5wt% of the acrylate monomer.

[0091] 100g of surface layer emulsion, 0.5g of defoamer, 1g of leveling agent and 1.5g of thickener were mixed, and ultraviolet absorber was added and stirred evenly to obtain surface layer slurry. The ultraviolet absorber was 2,4-dihydroxybenzophenone, and the amount was 3g.

[0092] (2) coating the surface slurry prepared in step (1) onto the surface of release paper with a coating thickness of 300 μm, drying at 120° C. for 2 min, coating the surface with an adhesive, and baking at 105° C. for 1 min. After baking, laminating one side of the adhesive with the microfiber base cloth, transferring to 130° C. for aging for 8 min, cooling, and removing the release paper to obtain the shoe leather.

[0093] Comparative Example 3: Example 3 was used as the control group. In Comparative Example 3, only the functional monomer A was bridged by p-hydroxybiphenol, and the other steps remained unchanged.

[0094] The specific adjustment steps are:

[0095] (1) S1: 0.1 mol of the intermediate, 0.23 mol of hydroxyethyl acrylate, 0.85 mol of anhydrous potassium carbonate and 500 mL of tetrahydrofuran were mixed, stirred evenly under nitrogen atmosphere, heated to 65° C., and refluxed for 42 h. After the reaction was completed, the mixture was cooled to room temperature, the product was collected, washed and dried to obtain functional monomer A.

[0096] S2: 0.11 mol of p-hydroxybiphenol and tetrahydrofuran are mixed and stirred evenly to obtain a p-hydroxybiphenol solution; the concentration of the p-hydroxybiphenol solution is 0.5 mol / L.

[0097] Take 0.2 mol of functional monomer A and 300 mL of tetrahydrofuran, mix, stir for 30 min, add p-hydroxybiphenol solution in a -20°C ice water bath, react for 8 h, heat to 25°C, continue to react for 4 h, filter and collect the product, wash and dry to obtain a flame retardant monomer.

[0098] Comparative Example 4: Example 3 was used as the control group. In Comparative Example 4, only the functional monomer B was bridged by p-hydroxybiphenol, and the other steps remained unchanged.

[0099] The specific adjustment steps are:

[0100] (1) S1: 0.22 mol of 2,3-epoxy-1-propanol and tetrahydrofuran were mixed and stirred to obtain a 2,3-epoxy-1-propanol solution; the concentration of the 2,3-epoxy-1-propanol solution was 0.6 mol / L.

[0101] Take 0.1 mol of the intermediate, 300 mL of tetrahydrofuran and 0.1 mol of sodium hydride, mix them, stir them evenly under a nitrogen environment, add 2,3-epoxy-1-propanol solution, react at 35°C for 3 hours, remove tetrahydrofuran by rotary evaporation after the reaction, collect the product, wash and dry it to obtain functional monomer B.

[0102] S2: 0.11 mol of p-hydroxybiphenol and tetrahydrofuran are mixed and stirred evenly to obtain a p-hydroxybiphenol solution; the concentration of the p-hydroxybiphenol solution is 0.5 mol / L.

[0103] Take 0.2 mol of functional monomer B and 300 mL of tetrahydrofuran, mix, stir for 30 min, add p-hydroxybiphenol solution in a -20°C ice water bath, react for 8 h, heat to 25°C, continue to react for 4 h, filter and collect the product, wash and dry to obtain a flame retardant monomer.

[0104] Detection experiment:

[0105] 1. Prepare the surface layer slurry according to the method disclosed in Examples 1-3 and Comparative Examples 1-4, pour it into a mold, dry it at 30°C for 48 hours, then transfer it to 80°C and dry it until the film reaches constant weight. After natural cooling, take out the surface layer film and perform performance testing on it:

[0106] Water resistance: Cut the surface film into rectangular strips of 20 mm × 15 mm, soak the rectangular strips in deionized water for 48 hours, take them out and wipe off the surface moisture, weigh the rectangular strips before and after soaking, and calculate the water absorption rate of the surface film.

[0107] Tensile strength: According to the test method disclosed in GB / T 528-2009 “Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber”, dumbbell-shaped specimens were prepared and their tensile strength was tested; the tensile rate was 500 mm / min.

[0108] Flame retardant properties: According to the method disclosed in GB / T2406-2009, the limiting oxygen index was tested, and the sample size was 150mm×6.5mm×3mm.

[0109] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Water absorption 2.1％ 2.0％ 2.0％ 3.8％ 5.1％ 2.6％ 3.3％ Tensile Strength 9.05MPa 9.07MPa 9.12MPa 7.87MPa 7.24MPa 8.76MPa 8.42MPa Limiting oxygen index 29.8 29.9 30.1 / 19.7 / /

[0110] 2. Shoe leather was prepared according to the method disclosed in Examples 1-3 and Comparative Examples 1-4. The sample size was 50 mm × 12 mm. The shoe leather was placed in a yellowing resistance test box for ultraviolet irradiation experiment. The ultraviolet power was 300 W, the irradiation time was 48 h, and the irradiation distance was 25 cm. The color difference of the sample before and after was tested with a colorimeter, and the sample was rated A according to the method disclosed in GB / T 250-2008.

[0111] Take a shoe leather sample, place it in a 70°C oven, let it stand for 10 days, observe the precipitation on its surface, and re-perform the ultraviolet irradiation experiment on it for 24 hours, and record the rating B.

[0112]

[0113] Conclusion: The polyurethane shoe leather prepared by this scheme not only has excellent water resistance, but also has excellent mechanical properties of the surface resin, yellowing resistance, high flame retardancy, and high practicality.

[0114] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A processing technology for waterproof and yellowing-resistant polyurethane shoe leather, characterized in that: The following steps are involved: (1) vacuum dehydrating polytetrahydrofuran diol, cooling to 60-65° C., adding isophorone diisocyanate and dibutyltin dilaurate, keeping the temperature at 90-95° C. for 2-3 hours, adding a chain extender, and continuing the reaction for 1-2 hours to obtain a polyurethane prepolymer; adding 1,4-butanediol, epoxy resin, hydroxyethyl acrylate and ultraviolet absorber modified flame retardant monomer to the polyurethane prepolymer, continuing the reaction for 1-1.5 hours, cooling to 40° C., standing for 0.5-1 hour, adding triethylamine for neutralization for 30 minutes, adding deionized water for emulsification for 30-40 minutes, and obtaining an epoxy resin modified polyurethane emulsion; Mixing acrylate monomer and potassium persulfate, adding epoxy resin modified polyurethane emulsion, stirring and reacting at 80-85° C. for 3-4 hours to obtain a surface layer emulsion; the acrylate monomer includes methyl methacrylate, ethyl acrylate and ultraviolet absorber modified flame retardant monomer; Mix the surface layer emulsion, defoamer, leveling agent and thickener, stir evenly to obtain a surface layer slurry; (2) coating the surface slurry prepared in step (1) onto the surface of release paper, drying at 110-120° C. for 2-3 min, coating the surface with a binder, baking at 100-105° C. for 1-2 min, laminating one side of the binder with the microfiber base cloth after baking, transferring to 120-130° C. for aging for 8-10 min, cooling, and removing the release paper to obtain the shoe leather; In step (1), the preparation steps of the ultraviolet absorber modified flame retardant monomer are: S1: Mix a UV absorber and tetrahydrofuran, and stir until dissolved to obtain a UV absorber solution; Mix hexachlorocyclotriphosphazene and tetrahydrofuran, add triethylamine and ultraviolet absorber solution at 75-85°C, reflux for 20-24h, remove tetrahydrofuran by rotary evaporation, collect the product, wash and dry to obtain an intermediate; S2: Take the intermediate, hydroxyethyl acrylate, anhydrous potassium carbonate and tetrahydrofuran, mix them, stir them evenly under nitrogen environment, heat them to 60-65°C, reflux them for 42-46 hours, cool them to room temperature after the reaction, collect the products, wash and dry them to obtain functional monomer A; S3: Mix 2,3-epoxy-1-propanol and tetrahydrofuran, and stir evenly to obtain a 2,3-epoxy-1-propanol solution; The intermediate, tetrahydrofuran and sodium hydride are mixed, stirred evenly under nitrogen atmosphere, 2,3-epoxy-1-propanol solution is added, reacted at 30-35° C. for 3-4 hours, tetrahydrofuran is removed by rotary evaporation after the reaction, the product is collected, washed and dried to obtain functional monomer B; S4: mixing p-hydroxybiphenol and tetrahydrofuran, stirring evenly to obtain a p-hydroxybiphenol solution; Take functional monomer A and tetrahydrofuran and mix them, add p-hydroxybiphenol solution in a -20°C ice water bath, react for 6 to 8 hours, then add functional monomer B, raise the temperature to 20 to 25°C, continue to react for 4 to 5 hours, collect the product by filtration, wash and dry to obtain a flame retardant monomer.

2. The processing technology of a waterproof and yellowing-resistant polyurethane shoe leather according to claim 1, characterized in that: In step (1), the molar ratio of the polytetrahydrofuran diol, isophorone diisocyanate, chain extender and 1,4-butanediol is 1:(5-6):2:1, the amount of the epoxy resin is 3-4wt% of the total amount of the polytetrahydrofuran diol and isophorone diisocyanate; the chain extender comprises dimethylol propionic acid and dimethylol butyric acid, and the molar ratio of the dimethylol propionic acid and dimethylol butyric acid is 1:1; the amount of the hydroxyethyl acrylate is 0.3-0.5wt% of the total amount of the polytetrahydrofuran diol and isophorone diisocyanate; when preparing the epoxy resin modified polyurethane emulsion, the amount of the ultraviolet absorber modified flame retardant monomer is 1.5-2wt% of the total amount of the polytetrahydrofuran diol and isophorone diisocyanate.

3. The processing technology of the waterproof and yellowing-resistant polyurethane shoe leather according to claim 1 is characterized in that: In step (1), in the acrylic ester monomer, the mass ratio of methyl methacrylate, ultraviolet absorber modified flame retardant monomer and ethyl acrylate is 5:3:1; the amount of the acrylic ester monomer is 3-4wt% of the total amount of polytetramethylene glycol, isophorone diisocyanate and chain extender.

4. The processing technology of the waterproof and yellowing-resistant polyurethane shoe leather according to claim 1 is characterized in that: In step (1), the contents of the components are as follows by mass: 100 to 105 parts of the surface layer emulsion, 0.3 to 0.5 parts of the defoaming agent, 0.5 to 1 parts of the leveling agent, and 1 to 1.5 parts of the thickener.

5. The processing technology of the waterproof and yellowing-resistant polyurethane shoe leather according to claim 1 is characterized in that: In step S1, the concentration of the ultraviolet absorber solution is 0.8-1 mol / L; the ultraviolet absorber is a compound of any one or more of p-hydroxyacetophenone, 4-hydroxybenzophenone, and 2,4-dihydroxybenzophenone; and the molar ratio of the hexachlorocyclotriphosphazene to the ultraviolet absorber is 1:(2-2.2).

6. The processing technology of the waterproof and yellowing-resistant polyurethane shoe leather according to claim 1, characterized in that: In step S2, the molar ratio of the intermediate to hydroxyethyl acrylate is 1:(2-2.3); In step S3, the concentration of the 2,3-epoxy-1-propanol solution is 0.6-0.8 mol / L; the molar ratio of the intermediate to 2,3-epoxy-1-propanol is 1:(2-2.2).

7. The processing technology of the waterproof and yellowing-resistant polyurethane shoe leather according to claim 1 is characterized in that: In step S4, the concentration of the p-hydroxybiphenol solution is 0.5-0.6 mol / L; the molar ratio of the functional monomer A, p-hydroxybiphenol, and functional monomer B is 1:(1-1.1):

1.

8. Polyurethane shoe leather processed according to the processing technology of waterproof and yellowing-resistant polyurethane shoe leather according to any one of claims 1 to 7.

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