Environmentally friendly automotive leather base fabric and preparation process thereof

Abstract

The invention relates to the technical field of automobile leather base fabrics, and discloses an environment-friendly automobile leather base fabric and a preparation process thereof. The method comprises the following steps: modifying casein by caprolactam to obtain modified casein; taking the prepared cyclodextrin MOF as a template and a reducing agent, in-situ growing a zinc acetate aqueous solution to obtain a ZnO-loaded cyclodextrin MOF; uniformly mixing the ZnO-loaded cyclodextrin MOF and the modified casein to obtain an emulsion A; sequentially reacting hexamethylene diisocyanate, a hydrophilic agent, isophorone diisocyanate, and a modified nano titanium dioxide composite material with cellulose acetate to obtain an emulsion B; sequentially reacting phosphorus oxychloride and 4,4-diaminodiphenylmethane with a polydopamine-modified nano silicon dioxide composite material to obtain an emulsion C; and adjusting the pH values ​​of the emulsions A, B, and C, and adopting a layer-by-layer assembly technology to prepare the environment-friendly automobile leather base fabric.

Description

Technical Field

[0001] The invention relates to the technical field of automobile leather base fabrics, in particular to an environmentally friendly automobile leather base fabric and a preparation process thereof. Background Art

[0002] As an important part of my country's light industry, leather base fabric has the properties of natural leather but also has similar disadvantages to natural leather, which greatly limits the further application and development of leather base fabric.

[0003] Traditional leather finishing agents can enhance the performance of leather base fabrics, correct surface defects of leather base fabrics, and expand the scope of leather use. However, due to the dense coating formed, the hygienic properties of leather base fabrics are poor. At the same time, traditional polyacrylate leather finishing agents also have defects such as "hot sticky and cold brittle", poor hygienic properties, poor mechanical properties, and inability to resist organic solvents, which limit their further application. The coating properties formed by traditional leather finishing agents are relatively single, and the effect of combining different finishing agents by dipping-drying methods will be greatly reduced; in the actual production process, there is a serious pollution problem.

[0004] Therefore, it is of great significance to invent an environmentally friendly leather finishing agent and adopt a special coating assembly technology to prepare an environmentally friendly automotive leather base fabric. Summary of the invention

[0005] The purpose of the present invention is to provide an environmentally friendly automotive leather base fabric and a preparation process thereof to solve the problems raised in the above background technology.

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

[0007] A preparation process of an environmentally friendly automotive leather base fabric comprises the following steps:

[0008] S1: heating a 1wt% acetic acid aqueous solution to 50-55°C, adding casein powder and stirring to dissolve, to obtain a casein solution; heating the casein solution to 75-80°C, adding a 25wt% caprolactam aqueous solution and keeping the temperature for reaction for 1-1.5h to obtain a modified casein;

[0009] S2: adding cyclodextrin MOF to zinc acetate aqueous solution and stirring evenly, adding 1 mol / L sodium hydroxide aqueous solution and stirring evenly, heating to 180-185°C for reaction for 12-14 hours, filtering, washing, and freeze-drying to obtain ZnO-loaded cyclodextrin MOF; mixing ZnO-loaded cyclodextrin MOF and modified casein evenly to obtain emulsion A;

[0010] S3: Add cellulose acetate to a mixed solution of butanone and methyl acetate and stir evenly to obtain solution B; preheat hexamethylene diisocyanate to 40-45°C under a nitrogen atmosphere, add solution B and a catalyst and heat to 50-55°C for reaction for 2-2.5h to obtain modified cellulose; stir a hydrophilic agent, isophorone diisocyanate, 1,4-butanediol, a dihydroxy polyether and a catalyst evenly under a nitrogen atmosphere, heat to 60-65°C for reaction for 1-1.5h to obtain a prepolymer; add the modified cellulose to the prepolymer, react at a constant temperature for 3-3.5h, cool to 40-45°C, add a modified nano-titanium dioxide composite material and react at a constant temperature for 1-1.5h, add triethylamine and react for 30-45min, cool to room temperature, emulsify, and remove the solvent by vacuum distillation to obtain emulsion B;

[0011] S4: adding the polydopamine-modified nano-silica composite material and phosphorus oxychloride to tetrahydrofuran, adding triethylamine to react at room temperature for 1-1.5 hours, adding 4,4-diaminodiphenylmethane to react at room temperature for 24 hours, purifying, and drying to obtain a modified nano-silica composite material; uniformly mixing the modified nano-silica composite material with modified casein to obtain emulsion C;

[0012] S5: adjusting the pH values ​​of emulsion A, emulsion B and emulsion C to (9-10), (4-5) and (9-10) respectively; immersing the leather base fabric in emulsion A, emulsion B and emulsion C in sequence for 3-5 minutes, with an interval of 1-2 minutes between each immersion; placing the impregnated leather base fabric in an oven at 50-55°C and drying for 8-10 hours to obtain an environmentally friendly automotive leather base fabric.

[0013] Furthermore, the weight proportions of the components in the emulsion A are: ZnO-loaded cyclodextrin MOF 0.8-1.2 wt %, and modified casein 98.8-99.2 wt %.

[0014] Furthermore, the weight proportions of the components in the emulsion C are as follows: 1.2-1.8 wt % of the modified nano-silicon dioxide composite material and 98.2-98.8 wt % of the modified casein.

[0015] Furthermore, the preparation method of the cyclodextrin MOF comprises the following steps:

[0016] Add cyclodextrin and potassium hydroxide into deionized water, stir evenly, filter, add the filtrate into methanol for ultrasonic dispersion, and obtain solution A; heat solution A to 60-65° C., let stand, ultrasonically treat and add polyethylene glycol, let stand, centrifuge, wash, and dry to obtain cyclodextrin MOF;

[0017] Furthermore, the mass ratio of cyclodextrin: potassium hydroxide: polyethylene glycol is (2.5-3):1:1; the ultrasonic treatment temperature is 60-65°C, the time is 10-15min, and the power is 500-580W.

[0018] Furthermore, the preparation method of the modified nano titanium dioxide composite material comprises the following steps:

[0019] 1wt% glacial acetic acid solution is added to the modified casein, stirred evenly to adjust the solid content, butyl titanate is added, heated to 120-125°C for reaction for 10-12h, centrifuged, washed, and dried to obtain a casein nano-titanium dioxide composite material; silane coupling agent KH550 is dispersed in an ethanol aqueous solution, the pH is adjusted to 4-5 and stirred evenly, the casein nano-titanium dioxide composite material is added and stirred evenly, heated to 75-80°C, the pH is adjusted to 9-10 and reacted for 4-5h, centrifuged, washed, and dried to obtain a modified nano-titanium dioxide composite material.

[0020] Furthermore, the glacial acetic acid solution adjusts the solid content of the modified casein to 0.45-0.5wt%; the amount of butyl titanate added is 0.06-0.08% of the total mass of the modified casein and 1wt% glacial acetic acid solution; and the mass ratio of the silane coupling agent KH550:casein nano-titanium dioxide composite material is (2-3):(1-1.2).

[0021] Furthermore, the preparation method of the polydopamine modified nano-silicon dioxide composite material comprises the following steps:

[0022] Silane coupling agent KH570 and 25wt% ammonia water are added to modified casein and mixed evenly, tetraethyl orthosilicate is added, heated to 110-115°C for reaction for 24-36h, centrifuged, washed, and dried to obtain a casein nano-silica composite material; the casein nano-silica composite material is added to a Tris-HCl buffer solution for ultrasonic dispersion, added to a dopamine hydrochloride solution, mixed evenly, stirred and reacted at room temperature for 12-24h to obtain a polydopamine modified nano-silica composite material.

[0023] Furthermore, the mass ratio of the silane coupling agent KH570: ammonia water: modified casein: tetraethyl orthosilicate is (2.5-3):5:(1-2):(3-5); the mass ratio of the casein nano-silica composite material: dopamine hydrochloride is 1:(2-2.5).

[0024] Furthermore, the mass ratio of casein powder to caprolactam is (2-4):(1-2); and the mass ratio of cyclodextrin MOF to zinc acetate is (1.2-2.4):1.

[0025] Furthermore, the mass ratio of the cellulose acetate:hexamethylene diisocyanate is (2-4):(0.5-1); the mass ratio of the hydrophilic agent:isophorone diisocyanate:1,4-butanediol:dihydroxy polyether is (1.5-2):4:(0.3-0.4):4; the mass ratio of the modified cellulose:prepolymer:modified nano-titanium dioxide composite material:triethylamine is (2-2.5):10:(0.1-0.2):0.3; the mass ratio of the polydopamine nano-silicon dioxide composite material:phosphorus oxychloride:4,4-diaminodiphenylmethane is (0.5-1):0.3:0.6.

[0026] Further, the hydrophilic agent is any one of dimethylol propionic acid and sodium 1,5-pentanediamine-3-sulfonate or a combination of both;

[0027] Furthermore, the hydrophilic agent is a mixture of dimethylolpropionic acid and 1,5-pentanediamine-3-sodium sulfonate, wherein the mass ratio of dimethylolpropionic acid to 1,5-pentanediamine-3-sodium sulfonate is 1:1.

[0028] Furthermore, the catalyst is dibutyltin dilaurate.

[0029] Furthermore, the leather base fabric is any one of a PVC leather base fabric and a PU leather base fabric.

[0030] Furthermore, the zinc acetate is zinc acetate dihydrate.

[0031] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0032] The present invention uses caprolactam-modified casein as a basic emulsion and adopts a layer-by-layer assembly method to form a three-layer composite coating on the surface of a leather base fabric. Compared with the coating formed by traditional coating-drying, the composite coating is formed by utilizing the principle of combining positive and negative charges between the emulsions. The coatings are more tightly combined with each other. At the same time, under the premise of ensuring the stability of the coating itself, the active substances between the coatings also have a synergistic effect.

[0033] The present invention uses polyethylene glycol as a surfactant in combination with an ultrasound-assisted method to rapidly synthesize a cyclodextrin metal organic framework, uses the cyclodextrin metal organic framework as a reducing agent and a template, and in situ grows and prepares a cyclodextrin MOF loaded with ZnO; the ZnO-loaded cyclodextrin MOF and modified casein are uniformly mixed to prepare an emulsion A; on the one hand, the ZnO-loaded cyclodextrin MOF can be uniformly dispersed in the modified casein under the action of cyclodextrin, thereby solving the problem that traditional ZnO nanoparticles have poor dispersibility and are easy to agglomerate in the emulsion; on the other hand, ZnO provides antibacterial properties for the coating while the ZnO released 2+ -COO in modified casein emulsion -, -NH2, and -OH form coordination bonds. Under the action of hydrogen bonds and coordination bonds, when small cracks form on the coating surface, they can be quickly repaired to maintain the basic properties of the coating. In addition, the ZnO-loaded cyclodextrin MOF itself has a large specific surface area and an ordered pore structure through the directional design of the topological structure and the expansion of organic functional groups, which greatly improves the air permeability of the leather base fabric and solves the problem that the traditional coating is dense and water vapor is difficult to diffuse to the outside, resulting in a decrease in hygiene performance and easy breeding of bacteria.

[0034] The invention uses modified casein as a template to prepare a casein nano-titanium dioxide composite material by in-situ polymerization; uses hexamethylene diisocyanate as a bridging agent to modify cellulose acetate to prepare an aqueous polymer emulsion; then uses dimethylolpropionic acid and 1,5-pentanediamine-3-sodium sulfonate as hydrophilic agents, isophorone diisocyanate as a chain extender, 1,4-butanediol and dihydroxy polyether as flexible segment regulators, and KH550 modified casein nano-titanium dioxide composite material as a modifier to prepare an emulsion B; sulfonate and carboxylate are simultaneously introduced into the emulsion, and the hydrogen bonding between 1,5-pentanediamine-3-sodium sulfonate and isophorone diisocyanate can accelerate the polymerization of dimethylolpropionic acid and isophorone diisocyanate. The reaction between emulsion A and emulsion C greatly improves the reaction rate and solves the problem of large steric hindrance and low reaction activity of -OH in the cellulose acetate structure; due to the presence of cellulose acetate in emulsion B, the coating formed by emulsion B serves as the intermediate layer between emulsion A and emulsion C, which can greatly improve the flexibility and mechanical properties of the coating; due to the introduction of sulfonic acid groups, the emulsion has both anionic and cationic properties and can have different ionization states under different pH environments, which provides a prerequisite for the layer-by-layer assembly of the present invention. When the emulsion is acidic, emulsion B presents a cationic positive charge, which just forms a mutual attraction with the negative charges carried by emulsion A and emulsion C, and jointly constructs a coating on the surface of the leather base fabric. The titanium dioxide nanocomposite material prepared by using modified casein as template has a particle size of about 500nm; the particle size of traditional nano-silica microspheres is only about 120nm, and the size of ZnO-loaded cyclodextrin MOF is about 200nm. The titanium dioxide nanocomposite material is added to emulsion B as a modifier. On the one hand, it can avoid the problem that traditional nano-silica microspheres are easy to block the MOF pore structure in emulsion A, resulting in reduced air permeability. On the other hand, the titanium dioxide nanomaterial in the form of microspheres has excellent dispersion performance in the emulsion. The -OH and -O2 generated on the surface under light conditions -It has a strong oxidative degradation effect on bacterial cell walls and organic matter, and synergistically improves the antibacterial performance with ZnO in emulsion A. The casein-modified nano-silicon dioxide composite material prepared by in-situ polymerization using modified casein as a template in emulsion C has a much smaller particle size than the titanium dioxide nano-composite material in emulsion B. It is staggered in the layer-by-layer self-assembly process, which not only ensures the air permeability of the leather base fabric, but also gives the leather base fabric excellent water resistance and wear resistance, greatly improving the service life of the leather base fabric.

[0035] The present invention uses modified casein as a template, prepares a casein-modified nano-silica composite material by in-situ polymerization, coats it with dopamine, and then uses phosphorus oxychloride and 4,4-diaminodiphenylmethane to modify it as a flame retardant to prepare emulsion C; uses the casein-modified nano-silica composite material as a carrier, uniformly disperses the flame retardant in the emulsion, and greatly improves the dispersion performance of the flame retardant.

[0036] The composite coating formed on the surface of the leather base fabric by emulsion A, emulsion B and emulsion C through layer-by-layer assembly technology gives the leather base fabric excellent mechanical properties, breathability, hydrophobicity, antibacterial properties and flame retardant properties; environmentally friendly raw materials are selected in the process of preparing each emulsion, and finally an environmentally friendly automotive leather base fabric is prepared. DETAILED DESCRIPTION

[0037] 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.

[0038] In the following examples, casein powder CAS: 9000-71-9, purchased from Shanghai McLean Biochemical Technology Co., Ltd.; caprolactam CAS: 105-60-2, purchased from Shanghai McLean Biochemical Technology Co., Ltd.; cyclodextrin CAS: 17465-86-0, purchased from Shanghai McLean Biochemical Technology Co., Ltd.; polyethylene glycol molecular weight is 8000, purchased from Aladdin Reagent (Shanghai) Co., Ltd.; zinc acetate dihydrate is purchased from China Pharmaceutical (Group) Shanghai Chemical Reagent Co., Ltd.; butyl titanate CAS: 5593-70-4, purchased from Aladdin Reagent (Shanghai) Co., Ltd.; cellulose acetate CAS: 9035-69-2, purchased from Nanjing Bermuda Biotechnology Co., Ltd.; dihydroxy polyether specification: N210, purchased from Shanghai McLean Biochemical Technology Co., Ltd.; tetraethyl orthosilicate CAS: 78-10-4, purchased from Aladdin Reagent (Shanghai) Co., Ltd.; the remaining raw materials are commercially available.

[0039] The preparation method of modified casein comprises the following steps: heating 98g of 1wt% acetic acid aqueous solution to 50°C, adding 2g of casein powder and stirring to dissolve, so as to obtain a casein solution; heating the casein solution to 75°C, adding 4mL of 25wt% caprolactam aqueous solution and keeping the temperature for reaction for 1h, so as to obtain modified casein.

[0040] Example 1: A process for preparing an environmentally friendly automotive leather base fabric: S1: Add 1 g of cyclodextrin and 0.4 g of potassium hydroxide to 40 mL of deionized water, stir evenly, filter, add the filtrate to 20 mL of methanol for ultrasonic dispersion to obtain solution A; heat solution A to 60°C, let stand for 10 min, ultrasonically treat and add 0.4 g of polyethylene glycol, let stand, centrifuge, wash, and dry to obtain cyclodextrin MOF; add 1.2 g of cyclodextrin MOF to 100 mL of 10 g / L zinc acetate aqueous solution and stir evenly, add 1 mol / L sodium hydroxide aqueous solution and stir evenly, heat to 180°C for reaction for 12 h, filter, wash, and freeze-dry to obtain ZnO-loaded cyclodextrin MOF; mix 0.8 g of ZnO-loaded cyclodextrin MOF with 99.2 g of modified casein to obtain emulsion A;

[0041] S2: Add 30g of 1wt% glacial acetic acid solution to 10g of modified casein, stir evenly, adjust the solid content to 0.5wt%, add 0.024g of butyl titanate, heat to 120°C, react for 10h, centrifuge, wash, and dry to obtain a casein nano-titanium dioxide composite material; disperse 2g of silane coupling agent KH550 in an ethanol solution, adjust the pH to 4 and stir evenly, add 1g of casein nano-titanium dioxide composite material, stir evenly, heat to 75°C, adjust the pH to 9 and react for 4h, centrifuge, wash, and dry to obtain a modified nano-titanium dioxide composite material;

[0042] S3: 2 g of cellulose acetate was added to a mixed solution of 8 g of butanone and 8 g of methyl acetate and stirred evenly to obtain solution B; 0.5 g of hexamethylene diisocyanate was preheated to 40°C under a nitrogen atmosphere, and solution B and 0.1 g of dibutyltin disilicate were added and heated to 50°C for reaction for 2 h to obtain modified cellulose; 1 g of dihydroxymethylpropionic acid, 1 g of sodium 1,5-pentanediamine-3-sulfonate, 4 g of isophorone diisocyanate, 0. 3g 1,4-butanediol, 4g dihydroxy polyether, and 0.2g dibutyltin disilicate were stirred evenly, heated to 60°C for reaction for 1h to obtain a prepolymer; 2g modified cellulose was added to 10g prepolymer, reacted at a constant temperature for 3h, cooled to 40°C, 0.1g modified nano titanium dioxide composite material was added, reacted at a constant temperature for 1h, 0.3g triethylamine was added, reacted for 30min, cooled to room temperature, emulsified, and the solvent was removed by vacuum distillation to obtain emulsion B;

[0043] S4: Add 2.5g of silane coupling agent KH570 and 5g of 25wt% ammonia water to modified casein and mix them evenly, add 1g of tetraethyl orthosilicate, heat to 110°C and react for 24h, centrifuge, wash, and dry to obtain a casein nano-silica composite material; add 1g of casein nano-silica composite material to 100mL of Tris-HCl buffer solution for ultrasonic dispersion, add 2g of dopamine hydrochloride solution and mix evenly, stir and react at room temperature for 12h to obtain a polydopamine modified nano-silica composite material;

[0044] S5: 0.5 g of polydopamine-modified nano-silica composite material and 0.3 g of phosphorus oxychloride were added to 50 mL of tetrahydrofuran, 0.5 g of triethylamine was added to react at room temperature for 1 h, 0.6 g of 4,4-diaminodiphenylmethane was added to react at room temperature for 24 h, purified, and dried to obtain a modified nano-silica composite material; 1.2 g of the modified nano-silica composite material was mixed evenly with 98.8 g of modified casein to obtain emulsion C;

[0045] S6: Adjust the pH of emulsion A, emulsion B and emulsion C to 9, 4 and 9 respectively; immerse the leather base fabric in emulsion A, emulsion B and emulsion C in turn for 3 minutes, with an interval of 1 minute between each immersion; place the impregnated leather base fabric in a 50°C oven and dry it for 8 hours to obtain an environmentally friendly automotive leather base fabric.

[0046] Example 2: A process for preparing an environmentally friendly automotive leather base fabric: S1: Add 1 g of cyclodextrin and 0.4 g of potassium hydroxide to 40 mL of deionized water, stir evenly, filter, add the filtrate to 20 mL of methanol for ultrasonic dispersion to obtain solution A; heat solution A to 60°C, let stand for 10 min, ultrasonically treat and add 0.4 g of polyethylene glycol, let stand, centrifuge, wash, and dry to obtain cyclodextrin MOF; add 1.6 g of cyclodextrin MOF to 100 mL of 10 g / L zinc acetate aqueous solution and stir evenly, add 1 mol / L sodium hydroxide aqueous solution and stir evenly, heat to 180°C for reaction for 12 h, filter, wash, and freeze-dry to obtain ZnO-loaded cyclodextrin MOF; mix 0.8 g of ZnO-loaded cyclodextrin MOF with 99.2 g of modified casein to obtain emulsion A;

[0047] S2: Add 30g of 1wt% glacial acetic acid solution to 10g of modified casein, stir evenly, adjust the solid content to 0.5wt%, add 0.028g of butyl titanate, heat to 120°C, react for 10h, centrifuge, wash, and dry to obtain a casein nano-titanium dioxide composite material; disperse 2g of silane coupling agent KH550 in ethanol solution, adjust the pH to 4 and stir evenly, add 1g of casein nano-titanium dioxide composite material, stir evenly, heat to 75°C, adjust the pH to 9 and react for 4h, centrifuge, wash, and dry to obtain a modified nano-titanium dioxide composite material;

[0048] S3: 2 g of cellulose acetate was added to a mixed solution of 8 g of butanone and 8 g of methyl acetate and stirred evenly to obtain solution B; 0.5 g of hexamethylene diisocyanate was preheated to 40°C under a nitrogen atmosphere, and solution B and 0.1 g of dibutyltin disilicate were added and heated to 50°C for reaction for 2 h to obtain modified cellulose; 1 g of dihydroxymethylpropionic acid, 1 g of sodium 1,5-pentanediamine-3-sulfonate, 4 g of isophorone diisocyanate, 0. 3g 1,4-butanediol, 4g dihydroxy polyether, and 0.2g dibutyltin disilicate were stirred evenly, heated to 60°C for reaction for 1h to obtain a prepolymer; 2g modified cellulose was added to 10g prepolymer, reacted at a constant temperature for 3h, cooled to 40°C, 0.1g modified nano titanium dioxide composite material was added, reacted at a constant temperature for 1h, 0.3g triethylamine was added, reacted for 30min, cooled to room temperature, emulsified, and the solvent was removed by vacuum distillation to obtain emulsion B;

[0049] S4: Add 2.5g of silane coupling agent KH570 and 5g of 25wt% ammonia water to modified casein and mix them evenly, add 1g of tetraethyl orthosilicate, heat to 110°C and react for 24h, centrifuge, wash, and dry to obtain a casein nano-silica composite material; add 1g of casein nano-silica composite material to 100mL of Tris-HCl buffer solution for ultrasonic dispersion, add 2g of dopamine hydrochloride solution and mix evenly, stir and react at room temperature for 12h to obtain a polydopamine modified nano-silica composite material;

[0050] S5: 0.5 g of polydopamine-modified nano-silica composite material and 0.3 g of phosphorus oxychloride were added to 50 mL of tetrahydrofuran, 0.5 g of triethylamine was added to react at room temperature for 1 h, 0.6 g of 4,4-diaminodiphenylmethane was added to react at room temperature for 24 h, purified, and dried to obtain a modified nano-silica composite material; 1.6 g of the modified nano-silica composite material was mixed evenly with 98.8 g of modified casein to obtain emulsion C;

[0051] S6: Adjust the pH of emulsion A, emulsion B and emulsion C to 9, 4 and 9 respectively; immerse the leather base fabric in emulsion A, emulsion B and emulsion C in turn for 3 minutes, with an interval of 1 minute between each immersion; place the impregnated leather base fabric in a 50°C oven and dry it for 8 hours to obtain an environmentally friendly automotive leather base fabric.

[0052] Example 3: A process for preparing an environmentally friendly automotive leather base fabric: S1: Add 1 g of cyclodextrin and 0.4 g of potassium hydroxide to 40 mL of deionized water, stir evenly, filter, add the filtrate to 20 mL of methanol for ultrasonic dispersion to obtain solution A; heat solution A to 60°C, let stand for 10 min, ultrasonically treat and add 0.4 g of polyethylene glycol, let stand, centrifuge, wash, and dry to obtain cyclodextrin MOF; add 2.4 g of cyclodextrin MOF to 100 mL of 10 g / L zinc acetate aqueous solution and stir evenly, add 1 mol / L sodium hydroxide aqueous solution and stir evenly, heat to 180°C for reaction for 12 h, filter, wash, and freeze-dry to obtain ZnO-loaded cyclodextrin MOF; mix 0.8 g of ZnO-loaded cyclodextrin MOF with 99.2 g of modified casein to obtain emulsion A;

[0053] S2: Add 30g of 1wt% glacial acetic acid solution to 10g of modified casein, stir evenly, adjust the solid content to 0.5wt%, add 0.032g of butyl titanate, heat to 120°C, react for 10h, centrifuge, wash, and dry to obtain a casein nano-titanium dioxide composite material; disperse 2g of silane coupling agent KH550 in an ethanol solution, adjust the pH to 4 and stir evenly, add 1g of casein nano-titanium dioxide composite material, stir evenly, heat to 75°C, adjust the pH to 9 and react for 4h, centrifuge, wash, and dry to obtain a modified nano-titanium dioxide composite material;

[0054] S3: 2 g of cellulose acetate was added to a mixed solution of 8 g of butanone and 8 g of methyl acetate and stirred evenly to obtain solution B; 0.5 g of hexamethylene diisocyanate was preheated to 40°C under a nitrogen atmosphere, and solution B and 0.1 g of dibutyltin disilicate were added and heated to 50°C for reaction for 2 h to obtain modified cellulose; 1 g of dihydroxymethylpropionic acid, 1 g of sodium 1,5-pentanediamine-3-sulfonate, 4 g of isophorone diisocyanate, 0. 3g 1,4-butanediol, 4g dihydroxy polyether, and 0.2g dibutyltin disilicate were stirred evenly, heated to 60°C for reaction for 1h to obtain a prepolymer; 2g modified cellulose was added to 10g prepolymer, reacted at a constant temperature for 3h, cooled to 40°C, 0.1g modified nano titanium dioxide composite material was added, reacted at a constant temperature for 1h, 0.3g triethylamine was added, reacted for 30min, cooled to room temperature, emulsified, and the solvent was removed by vacuum distillation to obtain emulsion B;

[0055] S4: Add 2.5g of silane coupling agent KH570 and 5g of 25wt% ammonia water to modified casein and mix them evenly, add 1g of tetraethyl orthosilicate, heat to 110°C and react for 24h, centrifuge, wash, and dry to obtain a casein nano-silica composite material; add 1g of casein nano-silica composite material to 100mL of Tris-HCl buffer solution for ultrasonic dispersion, add 2g of dopamine hydrochloride solution and mix evenly, stir and react at room temperature for 12h to obtain a polydopamine modified nano-silica composite material;

[0056] S5: 0.5 g of polydopamine-modified nano-silica composite material and 0.3 g of phosphorus oxychloride were added to 50 mL of tetrahydrofuran, 0.5 g of triethylamine was added to react at room temperature for 1 h, 0.6 g of 4,4-diaminodiphenylmethane was added to react at room temperature for 24 h, purified, and dried to obtain a modified nano-silica composite material; 1.8 g of the modified nano-silica composite material was mixed evenly with 98.8 g of modified casein to obtain emulsion C;

[0057] S6: Adjust the pH of emulsion A, emulsion B and emulsion C to 9, 4 and 9 respectively; immerse the leather base fabric in emulsion A, emulsion B and emulsion C in turn for 3 minutes, with an interval of 1 minute between each immersion; place the impregnated leather base fabric in a 50°C oven and dry it for 8 hours to obtain an environmentally friendly automotive leather base fabric.

[0058] Comparative Example 1: A preparation process of an environmentally friendly automotive leather base fabric: S1: 1 g of cyclodextrin and 0.4 g of potassium hydroxide were added to 40 mL of deionized water, stirred evenly, filtered, and the filtrate was added to 20 mL of methanol for ultrasonic dispersion to obtain solution A; solution A was heated to 60°C, allowed to stand for 10 min, ultrasonically treated and 0.4 g of polyethylene glycol was added, allowed to stand, centrifuged, washed, and dried to obtain cyclodextrin MOF; 2.4 g of cyclodextrin MOF was added to 100 mL of 30 g / L zinc acetate aqueous solution and stirred evenly, 1 mol / L sodium hydroxide aqueous solution was added and stirred evenly, heated to 180°C for reaction for 12 h, filtered, washed, and freeze-dried to obtain ZnO-loaded cyclodextrin MOF; 0.8 g of ZnO-loaded cyclodextrin MOF was mixed evenly with 99.2 g of modified casein to obtain emulsion A;

[0059] The remaining steps are the same as those in Example 1.

[0060] Comparative Example 2: A process for preparing an environmentally friendly automotive leather base fabric: S2: Add 30g of 1wt% glacial acetic acid solution to 10g of modified casein, stir evenly, adjust the solid content to 0.5wt%, add 0.096g of butyl titanate, heat to 120°C, react for 10h, centrifuge, wash, and dry to obtain a casein nano-titanium dioxide composite material; disperse 2g of silane coupling agent KH550 in an ethanol solution, adjust the pH to 4 and stir evenly, add 1g of casein nano-titanium dioxide composite material, stir evenly, heat to 75°C, adjust the pH to 9 and react for 4h, centrifuge, wash, and dry to obtain a modified nano-titanium dioxide composite material;

[0061] The remaining steps are the same as those in Example 1.

[0062] Comparative Example 3: A process for preparing an environmentally friendly automotive leather base fabric: S5: 0.5 g of a polydopamine-modified nano-silica composite material and 0.3 g of phosphorus oxychloride were added to 50 mL of tetrahydrofuran, 0.5 g of triethylamine was added to react at room temperature for 1 h, 0.6 g of 4,4-diaminodiphenylmethane was added to react at room temperature for 24 h, purified, and dried to obtain a modified nano-silica composite material; 3.6 g of the modified nano-silica composite material was uniformly mixed with 96.4 g of modified casein to obtain an emulsion C;

[0063] The remaining steps are the same as those in Example 1.

[0064] Comparative Example 4: S6: The leather base fabric was sequentially impregnated with emulsion A, emulsion B, and emulsion C for 3 minutes, dried at 50°C for 15 minutes, and impregnated again; the impregnated leather base fabric was placed in a 50°C oven and dried for 8 hours to obtain an environmentally friendly automotive leather base fabric;

[0065] The remaining steps are the same as those in Example 1.

[0066] test:

[0067] Mechanical properties test: The tensile strength and elongation at break of the leather base fabric were measured using a universal testing machine at a tensile rate of 100 mm / min.

[0068] Air permeability test: Use a leather air permeability tester to measure the air permeability of leather. First, measure the time t0 for 100mL of air to pass through the blank sample, then test the time t1 for 100mL of air to pass through the environmentally friendly automotive leather base fabric, and calculate the air permeability V=100×3600 / 10×(t1-t0).

[0069] Contact angle test: Drop 5 μL of deionized water on the surface of the leather base fabric and measure the water contact angle using a contact angle tester.

[0070] Flame retardant performance test: refer to ASTM D2863 and use a limiting oxygen index tester to test the leather base fabric.

[0071]

[0072] Conclusion: The leather base fabrics prepared in Examples 1-3 have excellent mechanical properties, air permeability, hydrophobicity and flame retardant properties.

[0073] The addition of excessive zinc nitrate dihydrate in Comparative Example 1 resulted in excessive ZnO generation, which destroyed the framework structure of the cyclodextrin MOF itself, causing it to lose its porous structure and reduce its air permeability.

[0074] The addition of excessive butyl titanate in Comparative Example 2 resulted in excessive generation of too many TiO2 crystals, which caused the modified casein micelles to be completely coated. The surface of the prepared nanospheres lacked micelle segments, resulting in reduced dispersibility in the emulsion and reduced mechanical properties.

[0075] In Comparative Example 3, adding an excessive amount of modified nano-silica composite material results in a large amount of agglomeration in emulsion C, resulting in reduced dispersion performance, stress concentration, and reduced hydrophobicity and mechanical properties.

[0076] In Comparative Example 4, ordinary step-by-step drying method is adopted to form a coating, and emulsion A, emulsion B, and emulsion C are coated and dried in sequence to compound the coating. The layers are relatively independent and cannot form a synergistic effect, resulting in reduced performance.

[0077] 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 process for preparing an environmentally friendly automotive leather base fabric, characterized in that: The following steps are involved: S1: heating a 1wt% acetic acid aqueous solution to 50-55°C, adding casein powder and stirring to dissolve, to obtain a casein solution; heating the casein solution to 75-80°C, adding a 25wt% caprolactam aqueous solution and keeping the temperature for reaction for 1-1.5h to obtain a modified casein; S2: adding cyclodextrin MOF to zinc acetate aqueous solution and stirring evenly, adding 1 mol / L sodium hydroxide aqueous solution and stirring evenly, heating to 180-185°C for reaction for 12-14 hours, filtering, washing, and freeze-drying to obtain ZnO-loaded cyclodextrin MOF; mixing ZnO-loaded cyclodextrin MOF and modified casein evenly to obtain emulsion A; S3: hexamethylene diisocyanate, a hydrophilic agent, isophorone diisocyanate, and a modified nano-titanium dioxide composite material are reacted with cellulose acetate in sequence to obtain emulsion B; S4: phosphorus oxychloride and 4,4-diaminodiphenylmethane are reacted with the polydopamine-modified nano-silica composite material in sequence to obtain emulsion C; S5: adjusting the pH of emulsion A, emulsion B, and emulsion C to (9-10), (4-5), and (9-10), respectively; dipping the leather base fabric into emulsion A, emulsion B, and emulsion C in sequence for 3-5 minutes, with an interval of 1-2 minutes between each dipping; placing the impregnated leather base fabric in a 50-55° C. oven and drying it for 8-10 hours to obtain an environmentally friendly automotive leather base fabric; The preparation method of the cyclodextrin MOF comprises the following steps: Add cyclodextrin and potassium hydroxide into deionized water, stir evenly, filter, add the filtrate into methanol for ultrasonic dispersion, and obtain solution A; heat solution A to 60-65° C., let stand, ultrasonically treat and add polyethylene glycol, let stand, centrifuge, wash, and dry to obtain cyclodextrin MOF; The preparation method of the modified nano titanium dioxide composite material comprises the following steps: Add 1wt% glacial acetic acid solution to modified casein, stir evenly to adjust the solid content, add butyl titanate, heat to 120-125°C, react for 10-12h, centrifuge, wash, and dry to obtain a casein nano-titanium dioxide composite material; disperse silane coupling agent KH550 in ethanol aqueous solution, adjust pH to 4-5, stir evenly, add casein nano-titanium dioxide composite material, stir evenly, heat to 75-80°C, adjust pH to 9-10, react for 4-5h, centrifuge, wash, and dry to obtain a modified nano-titanium dioxide composite material; The preparation method of the polydopamine modified nano-silicon dioxide composite material comprises the following steps: Silane coupling agent KH570 and 25wt% ammonia water are added to modified casein and mixed evenly, tetraethyl orthosilicate is added, heated to 110-115°C for reaction for 24-36h, centrifuged, washed, and dried to obtain a casein nano-silica composite material; the casein nano-silica composite material is added to a Tris-HCl buffer solution for ultrasonic dispersion, added to a dopamine hydrochloride solution, mixed evenly, stirred and reacted at room temperature for 12-24h to obtain a polydopamine modified nano-silica composite material.

2. The process for preparing an environmentally friendly automotive leather base fabric according to claim 1, characterized in that: The following steps are involved: S3: Add cellulose acetate to a mixed solution of butanone and methyl acetate and stir evenly to obtain solution B; preheat hexamethylene diisocyanate to 40-45°C under a nitrogen atmosphere, add solution B and a catalyst and heat to 50-55°C for reaction for 2-2.5h to obtain modified cellulose; stir a hydrophilic agent, isophorone diisocyanate, 1,4-butanediol, a dihydroxy polyether and a catalyst evenly under a nitrogen atmosphere, heat to 60-65°C for reaction for 1-1.5h to obtain a prepolymer; add the modified cellulose to the prepolymer, react at a constant temperature for 3-3.5h, cool to 40-45°C, add a modified nano-titanium dioxide composite material and react at a constant temperature for 1-1.5h, add triethylamine and react for 30-45min, cool to room temperature, emulsify, and remove the solvent by vacuum distillation to obtain emulsion B; S4: adding the polydopamine-modified nano-silica composite material and phosphorus oxychloride to tetrahydrofuran, adding triethylamine to react at room temperature for 1-1.5 hours, adding 4,4-diaminodiphenylmethane to react at room temperature for 24 hours, purifying, and drying to obtain a modified nano-silica composite material; uniformly mixing the modified nano-silica composite material with modified casein to obtain emulsion C; The weight proportions of the components in the emulsion C are as follows: 1.2-1.8 wt % of the modified nano-silicon dioxide composite material and 98.2-98.8 wt % of the modified casein.

3. The process for preparing an environmentally friendly automotive leather base fabric according to claim 1, characterized in that: The mass ratio of cyclodextrin: potassium hydroxide: polyethylene glycol is (2.5-3): 1: 1; the ultrasonic treatment temperature is 60-65°C, the time is 10-15min, and the power is 500-580W.

4. The process for preparing an environmentally friendly automotive leather base fabric according to claim 1, characterized in that: The glacial acetic acid solution adjusts the solid content of modified casein to 0.45-0.5wt%; the amount of butyl titanate added is 0.06-0.08% of the total mass of the modified casein and 1wt% glacial acetic acid solution; the mass ratio of the silane coupling agent KH550: casein nano-titanium dioxide composite material is (2-3):(1-1.2).

5. The process for preparing an environmentally friendly automotive leather base fabric according to claim 1, characterized in that: The mass ratio of the silane coupling agent KH570: ammonia water: modified casein: tetraethyl orthosilicate is (2.5-3):5:(1-2):(3-5); the mass ratio of the casein nano-silica composite material: dopamine hydrochloride is 1:(2-2.5).

6. The process for preparing an environmentally friendly automotive leather base fabric according to claim 1, characterized in that: The mass ratio of casein powder to caprolactam is (2-4):(1-2); the mass proportion of each component in the emulsion A is 0.8-1.2wt% of ZnO-loaded cyclodextrin MOF and 98.8-99.2wt% of modified casein; the mass ratio of the cyclodextrin MOF to zinc acetate is (1.2-2.4):

1.

7. The process for preparing an environmentally friendly automotive leather base fabric according to claim 2, characterized in that: The mass ratio of cellulose acetate: hexamethylene diisocyanate is (2-4): (0.5-1); the mass ratio of the hydrophilic agent: isophorone diisocyanate: 1,4-butanediol: dihydroxy polyether is (1.5-2): 4: (0.3-0.4): 4; the mass ratio of the modified cellulose: prepolymer: modified nano titanium dioxide composite material: triethylamine is (2-2.5): 10: (0.1-0.2): 0.3; the hydrophilic agent is any one of dihydroxymethyl propionic acid and 1,5-pentanediamine-3-sodium sulfonate or a combination of two thereof; the mass ratio of the polydopamine nano silicon dioxide composite material: phosphorus oxychloride: 4,4-diaminodiphenylmethane is (0.5-1): 0.3: 0.

6.

8. Automobile leather base fabric prepared according to the preparation process of an environmentally friendly automobile leather base fabric according to any one of claims 1 to 7.

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