Velvet color-changing Yangbuck leather and preparation method thereof

Abstract

The invention discloses velvet color-changing Yangbuck leather and a preparation method thereof, and belongs to the technical field of artificial leather. The method is used for solving the technical problems that in the prior art, the Yangbuck leather preparation process is complex and tedious, on the premise that excellent mechanical strength of Yangbuck leather is kept, the Yangbuck leather has the fluff touch feeling and high temperature resistance, and the attractiveness is improved by increasing the color changing effect. The preparation method of the velvet color-changing Yangbuck leather comprises the following steps: S1, foaming a mixture to obtain a semi-finished product of the Yangbuck leather; performing ultraviolet radiation on the semi-finished Yangbuck to form a semi-finished modified Yangbuck; and S2, the surface of the modified Yangbuck semi-finished product is coated with the coating composition in a blade coating mode, a film layer is formed, and the prepared velvet color-changing Yangbuck is obtained. Wherein when the high-temperature-resistant discoloration polyurethane is prepared, a polymerization chain extender is added as a reinforcing agent, and spirophora is added as a color assisting agent; wherein the polymerization chain extender is obtained by carrying out polymerization reaction on pyromellitic dianhydride and 3, 5-diethyl-2, 4-toluenediamine.

Description

Technical Field

[0001] This invention relates to the field of artificial leather technology, specifically to a velvety, color-changing sheepskin leather and its preparation method. Background Technology

[0002] Genuine leather products derived from animal fur possess excellent properties such as softness, a plush feel, and warmth. However, due to the environmentally conscious principle that large-scale animal farming and slaughter are detrimental to sustainable development, sheepskin, as a synthetic leather, has become the preferred alternative to genuine leather products. The core of sheepskin production lies in using a foaming agent to generate gas under specific conditions, causing the coating to expand and form a uniformly distributed cell structure, ultimately creating a plush feel. In the sheepskin production process, the foaming material needs to be dispersed in PU resin. The foaming powder expands in volume at high temperatures, therefore the PU resin must have a certain degree of high-temperature resistance to achieve optimal foaming results. Furthermore, with the continuous improvement of people's aesthetic requirements for leather products, how to produce sheepskin with various colors and varieties is also one of the directions for current technological innovation.

[0003] Patent application CN106436337A discloses a complete preparation process for water-based sheepskin leather with a heat-pressing effect. Water-based wet-process base slurry is fully bonded to a base fabric to obtain water-based base; water-based sheepskin material is coated onto release paper, and after leveling and drying, a sheepskin veneer is formed. The water-based base is bonded to the sheepskin veneer, and then the release paper is peeled off to obtain artificial leather. The artificial leather undergoes high-temperature foaming, color modification, and heat pressing to obtain the final product. However, traditional sheepskin leather processing is relatively complex, resulting in low yields that do not meet current market demands. Therefore, how to use a simplified and efficient process to prepare soft, comfortable, and color-changing sheepskin leather is an urgent technical problem to be solved.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a velvety, color-changing sheepskin leather and its preparation method, which solves the technical problem in the prior art of how to prepare sheepskin leather with a velvety feel, color changeability, and good mechanical properties through innovative optimization of materials and processes.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing velvety, color-changing sheepskin leather includes the following steps:

[0008] S1. The mixture is foamed to obtain sheepskin semi-finished product; the sheepskin semi-finished product is irradiated with ultraviolet light to form modified sheepskin semi-finished product;

[0009] S2. The coating composition is scraped onto the surface of the modified sheepskin semi-finished product to form a film layer. After drying and cooling, the prepared velvety color-changing sheepskin is obtained.

[0010] Further, in step S1, the method for preparing the mixture includes the following steps:

[0011] B1. Add pyromellitic anhydride to N-methylpyrrolidone, heat to 30-35℃, and stir thoroughly until the pyromellitic anhydride is completely dissolved; then add 3,5-diethyl-2,4-toluenediamine to obtain the reaction system; heat the reaction system to 80-90℃ and continue the reaction at this temperature for 4-6 hours. After post-processing, the polymerization chain extender is prepared.

[0012] The amino group of 3,5-diethyl-2,4-toluenediamine undergoes a nucleophilic substitution reaction with the anhydride of pyromellitic anhydride to prepare a polymeric chain extender. The reaction principle is as follows:

[0013]

[0014] B2, 1,4-Butanediol, dibutyltin dilaurate, and N,N-dimethylacetamide were mixed to obtain component A; isophorone diisocyanate was dissolved in N,N-dimethylacetamide to obtain component B; component B was added dropwise to component A, and the temperature was raised to 75-85℃, and the reaction was carried out at this temperature for 2-3 hours; then a polymerization chain extender and a colorant were added, and the temperature was lowered to 70-75℃, and the reaction was carried out at this temperature for 6-8 hours to obtain the product; the product was cured to prepare a high-temperature resistant color-changing polyurethane;

[0015] B3. Mix high-temperature resistant color-changing polyurethane, silicone leveling agent, silicone defoamer and water to obtain a mixture; add sheep bark foaming powder to the mixture and stir evenly to obtain the prepared mixture.

[0016] Further, in step B1, the ratio of N-methylpyrrolidone, pyromellitic anhydride and 3,5-diethyl-2,4-toluenediamine is 200-300 mL: 10-20 g: 20-40 mL.

[0017] Further, in step B2, the ratio of 1,4-butanediol, dibutyltin dilaurate, and N,N-dimethylacetamide is 10-20 mL: 0.1-0.5 g: 10-20 mL; the ratio of component A, component B, and polymerization chain extender is 30-40 mL: 20-40 mL: 5-10 g; in step B3, the weight ratio of high-temperature resistant color-changing polyurethane, silicone leveling agent, silicone defoamer, water, and sheep bark foaming powder is 30-40: 2-5: 2-5: 40-50: 5-10.

[0018] Furthermore, in step S1, the foaming temperature is 120-130℃, the foaming time is 8-12s, the ultraviolet irradiation wavelength is 365nm, and the external irradiation intensity is 0.6-0.8W / m. 2 The duration of ultraviolet irradiation is 5-10 minutes.

[0019] Further, in step S1, the method for preparing the coating composition includes the following steps:

[0020] A1. Methyltrichlorosilane, deionized water and n-butanol are mixed and reacted in a closed system. After standing and separating into layers, the organic liquid layer is collected, which is the prepared low crosslinking cyclic siloxane.

[0021] Using n-butanol as a solvent, methyltrichlorosilane is hydrolyzed to a low degree to obtain a cyclic siloxane with a low degree of crosslinking.

[0022] A2. Mix water-based acrylic resin coating, potassium persulfate solution and isobutyl acrylate to form a mixed system; heat the mixed system to 70-80℃ and react at this temperature for 30-60 minutes to obtain a crosslinked emulsion.

[0023] A3. The coating composition is prepared by mixing cross-linked emulsion, fly ash microspheres, and low-crosslinked cyclic siloxane.

[0024] Further, in step A1, the ratio of methyltrichlorosilane, deionized water and n-butanol is 15-25mL:20-30mL:3-7mL; in step A2, the ratio of waterborne acrylic resin coating, potassium persulfate solution and isobutyl acrylate is 100-120mL:5-10mL:5-10mL.

[0025] Further, in step A3, the weight ratio of the crosslinked emulsion, isobutyl acrylate, and low-crosslinking cyclic siloxane is 100-120:5-10:3-10.

[0026] Furthermore, the film thickness is 1.5-2 mm; the drying temperature is 60-70℃; and the drying time is 5-10 min.

[0027] As another aspect of the present invention, a method for preparing velvety color-changing sheepskin leather is provided.

[0028] The present invention has the following beneficial effects:

[0029] 1. High-temperature resistant color-changing polyurethane, additives, and sheepskin foaming powder are used as raw materials. Through foaming and ultraviolet irradiation processes, modified sheepskin semi-finished products are obtained. A coating composition is then applied to the surface of the modified sheepskin semi-finished product to obtain velvety color-changing sheepskin. Conventional polyurethane has low mechanical properties, poor heat resistance, and a narrow operating temperature range. In the synthesis of polyurethane in this invention, isophorone diisocyanate and 1,4-butanediol are used as raw materials, spiropyrano containing dihydroxy compounds is used as a colorant, a polymeric chain extender is used as a reinforcing agent, and N,N-dimethylformamide is used as a solvent. Through polymerization and curing reactions, high-temperature resistant color-changing polyurethane is prepared. Pyromellitic anhydride and 3,5-diethyl-2,4-toluenediamine undergo a polymerization reaction to prepare a polymeric chain extender; the above-mentioned polymeric chain extender can significantly improve the high-temperature resistance and mechanical strength of the prepared polyurethane. Furthermore, 3,5-diethyl-2,4-toluenediamine itself can serve as an aromatic diamine curing agent for the synthesis of polyurethane elastomers. During the polyurethane synthesis process, spiropyrans with dihydroxyl groups can react with it. Polyurethane can undergo a ring-opening reaction upon exposure to ultraviolet light or under stress, thus developing color.

[0030] 2. A certain amount of coating composition is applied to the surface of the modified sheepskin semi-finished product. This coating composition, applied to the sheepskin surface, not only creates a plush texture but also forms a protective film, preventing the sheepskin from easily absorbing moisture. The coating composition includes a crosslinked emulsion, fly ash microspheres, and low-crosslinking cyclic siloxanes. The crosslinked emulsion is obtained by reacting waterborne acrylic resin coating, isobutyl acrylate, and low-crosslinking cyclic siloxanes. The cured product in the waterborne acrylic resin coating is a copolymer synthesized primarily from monomers such as acrylates, methacrylates, and styrene. Adding a small amount of isobutyl acrylate helps improve the thermal stability, volatility, and gloss of the film-forming material. A small amount of fly ash microspheres can exert morphological, reactive, and micro-aggregate effects, enhancing the fluidity of the coating composition, making it easier to disperse uniformly, and optimizing the microporous effect. The sheepskin semi-finished product undergoes non-high-intensity ultraviolet irradiation treatment, which can pre-sterilize and prevent mold growth. Furthermore, its surface can generate a small amount of carbonyl and hydroxyl free radicals, which can connect and react with the crosslinked emulsion and polysiloxane in the coating composition, thereby preparing a highly adhesive, velvety, color-changing sheepskin leather. The sheepskin leather products prepared by this invention have the advantages of high mechanical strength, heat and weather resistance, high surface velvet feel and gloss, and the ability to change color naturally. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] The water-based acrylic resin coatings used in Examples 1-3 of this invention were purchased from Shanghai Kaiyin Chemical Co., Ltd., specifically Mitsubishi brand acrylic resin from Japan; the fly ash microspheres used in Examples 1-3 of this invention were purchased from Xingtai Shuoxing Refractory Materials Co., Ltd., with a particle size of 30 mesh; the color pastes used in Examples 1-3 of this invention were purchased from Xinxiang Haichuan New Materials Technology Co., Ltd.; the sheep bark foaming powder used in Examples 4-6 of this invention was purchased from Dongguan Caiguan Industrial Materials Co., Ltd.; and the silicone leveling agent used in Examples 4-6 of this invention was purchased from Ezhou Anjikang Technology Co., Ltd., with a density of 1.05 kg / cm³. 3 The silicone defoamer used in Examples 4-6 of this invention was purchased from Daejeon Chemical, model AT-618.

[0033] Example 1

[0034] This embodiment provides a method for preparing a coating composition for velvety, color-changing sheepskin, comprising the following steps:

[0035] A1. Select a 250mL beaker, add 15mL of methyltrichlorosilane, 20mL of deionized water and 3 parts of n-butanol to the beaker, mix well, seal the beaker, stir and react at room temperature for 2h, let stand to separate the layers, and then collect the organic layer liquid, which is the prepared low crosslinking cyclic siloxane.

[0036] A2. In a 250 mL round-bottom flask equipped with a stirrer, condenser, and thermometer, add 100 mL of water-based acrylic resin coating, 5 mL of 5 wt% potassium persulfate solution, 5 mL of isobutyl acrylate, and 10 mL of low-crosslinking cyclic siloxane sequentially. Mix well to form a mixed system. Transfer the round-bottom flask to a water bath and heat to 70 °C. React at this temperature for 30 min, then allow to cool naturally to room temperature to obtain a crosslinked emulsion.

[0037] A3. By weight, 100 parts of crosslinked emulsion, 5 parts of fly ash microspheres, and 3 parts of low-crosslinking cyclic siloxane are mixed to obtain the prepared coating composition.

[0038] Example 2

[0039] This embodiment provides a method for preparing a coating composition for velvety, color-changing sheepskin, comprising the following steps:

[0040] A1. Select a 250mL beaker, add 20mL of methyltrichlorosilane, 25mL of deionized water and 5 parts of n-butanol to the beaker, mix well, seal the beaker, stir and react at room temperature for 3h, let stand and separate into layers, and then collect the organic layer liquid, which is the prepared low crosslinking cyclic siloxane.

[0041] A2. In a 250 mL round-bottom flask equipped with a stirrer, condenser, and thermometer, add 110 mL of water-based acrylic resin coating, 8 mL of 6 wt% potassium persulfate solution, 7 mL of isobutyl acrylate, and 13 mL of low-crosslinking cyclic siloxane sequentially. Mix well to form a mixed system. Transfer the round-bottom flask to a water bath and heat to 75 °C. React at this temperature for 45 min, then allow to cool naturally to room temperature to obtain a crosslinked emulsion.

[0042] A3. By weight, 110 parts of crosslinked emulsion, 8 parts of fly ash microspheres, and 6 parts of low-crosslinking cyclic siloxane are mixed to obtain the prepared coating composition.

[0043] Example 3

[0044] This embodiment provides a method for preparing a coating composition for velvety, color-changing sheepskin, comprising the following steps:

[0045] A1. Select a 250mL beaker, add 25mL of methyltrichlorosilane, 30mL of deionized water and 7 parts of n-butanol to the beaker, mix well, seal the beaker, stir and react at room temperature for 2-4 hours, let stand to separate the layers, and then collect the organic liquid layer, which is the prepared low crosslinking cyclic siloxane.

[0046] A2. In a 250 mL round-bottom flask equipped with a stirrer, condenser, and thermometer, add 120 mL of water-based acrylic resin coating, 10 mL of 10 wt% potassium persulfate solution, 10 mL of isobutyl acrylate, and 20 mL of low-crosslinking cyclic siloxane sequentially. Mix well to form a mixed system. Transfer the round-bottom flask to a water bath and heat to 80 °C. React at this temperature for 60 min, then allow to cool naturally to room temperature to obtain a crosslinked emulsion.

[0047] A3. By weight, 120 parts of crosslinked emulsion, 10 parts of fly ash microspheres and 10 parts of low crosslinking degree cyclic siloxane are mixed to obtain the prepared coating composition.

[0048] Example 4

[0049] This embodiment provides a method for preparing a blend for velvety, color-changing sheepskin, comprising the following steps:

[0050] B1. Select a 500mL three-necked flask equipped with a spherical condenser and mechanical stirrer. Add 200mL of N-methylpyrrolidone and 10g of pyromellitic anhydride. Transfer the flask to a water bath and heat to 30℃. Stir thoroughly until the pyromellitic anhydride is completely dissolved. Then add 20mL of 3,5-diethyl-2,4-toluenediamine to the flask to obtain the reaction system. Heat the flask to 80℃ and continue the reaction at this temperature for 4 hours. After that, stop stirring and heating, and dismantle the reaction apparatus. Filter the solution from the flask. Wash the filter cake successively with acetone and deionized water, and dry it under vacuum at 55℃ to constant weight. This is the prepared polymer chain extender.

[0051] B2. Select a 100mL Erlenmeyer flask, add 10mL of 1,4-butanediol and 0.1g of dibutyltin dilaurate, and then add 10mL of N,N-dimethylacetamide. Mix well to obtain component A. Dissolve 10g of isophorone diisocyanate in 20mL of N,N-dimethylacetamide to obtain component B. Add 30mL of component B dropwise to the Erlenmeyer flask, heat the flask to 75℃, and react at this temperature for 2 hours. Then add 5g of polymerization chain extender and 3g of colorant spiropyran to the Erlenmeyer flask, cool to 70℃, and continue the reaction at this temperature for 6 hours to obtain the product. Pour the product into a polyethylene mold and dry and cure in an oven at 75℃ for 22 hours to obtain the prepared high-temperature resistant color-changing polyurethane.

[0052] B3. According to the weight, mix 30 parts of high temperature resistant color-changing polyurethane, 2 parts of silicone leveling agent, 2 parts of silicone defoamer and 40 parts of water to obtain a mixture; then add 5 parts of sheep bark foaming powder to the above mixture and stir evenly to obtain the prepared mixture.

[0053] Example 5

[0054] This embodiment provides a method for preparing a blend for velvety, color-changing sheepskin, comprising the following steps:

[0055] B1. Select a 500mL three-necked flask equipped with a spherical condenser and mechanical stirrer. Add 250mL of N-methylpyrrolidone and 15g of pyromellitic anhydride. Transfer the flask to a water bath and heat to 32℃. Stir thoroughly until the pyromellitic anhydride is completely dissolved. Then add 30mL of 3,5-diethyl-2,4-toluenediamine to the flask to obtain the reaction system. Heat the flask to 85℃ and continue the reaction at this temperature for 5 hours. Then stop stirring and heating, and dismantle the reaction apparatus. Filter the solution from the three-necked flask. Wash the filter cake successively with acetone and deionized water, and dry it under vacuum at 58℃ to constant weight. This is the prepared polymer chain extender.

[0056] B2. Select a 100mL Erlenmeyer flask, add 15mL of 1,4-butanediol and 0.3g of dibutyltin dilaurate, and then add 15mL of N,N-dimethylacetamide. Mix well to obtain component A. Dissolve 15g of isophorone diisocyanate in 25mL of N,N-dimethylacetamide to obtain component B. Add 35mL of component B dropwise to the Erlenmeyer flask, heat the flask to 80℃, and react at this temperature for 2.5h. Then add 8g of polymerization chain extender and 4g of colorant spiropyran to the Erlenmeyer flask, cool to 72℃, and continue the reaction at this temperature for 7h to obtain the product. Pour the product into a polyethylene mold and dry and cure in an oven at 78℃ for 23h to obtain the prepared high-temperature resistant color-changing polyurethane.

[0057] B3. According to the weight, mix 35 parts of high temperature resistant color-changing polyurethane, 3 parts of silicone leveling agent, 3 parts of silicone defoamer and 45 parts of water to obtain a mixture; then add 8 parts of sheep bark foaming powder to the above mixture and stir evenly to obtain the prepared mixture.

[0058] Example 6

[0059] This embodiment provides a method for preparing a blend for velvety, color-changing sheepskin, comprising the following steps:

[0060] B1. Select a 500mL three-necked flask equipped with a spherical condenser and mechanical stirrer. Add 300mL of N-methylpyrrolidone and 20g of pyromellitic anhydride. Transfer the flask to a water bath and heat to 35℃. Stir thoroughly until the pyromellitic anhydride is completely dissolved. Then add 40mL of 3,5-diethyl-2,4-toluenediamine to the flask to obtain the reaction system. Heat the flask to 90℃ and continue the reaction at this temperature for 6 hours. After that, stop stirring and heating, and dismantle the reaction apparatus. Filter the solution from the three-necked flask. Wash the filter cake successively with acetone and deionized water, and dry it under vacuum at 60℃ to constant weight. This is the prepared polymer chain extender.

[0061] B2. Select a 100mL Erlenmeyer flask, add 20mL of 1,4-butanediol and 0.5g of dibutyltin dilaurate, and then add 20mL of N,N-dimethylacetamide. Mix well to obtain component A. Dissolve 20g of isophorone diisocyanate in 30mL of N,N-dimethylacetamide to obtain component B. Add 40mL of component B dropwise to the Erlenmeyer flask, heat the flask to 85℃, and react at this temperature for 3h. Then add 10g of polymerization chain extender and 4g of colorant spiropyran to the Erlenmeyer flask, cool to 75℃, and continue the reaction at this temperature for 8h to obtain the product. Pour the product into a polyethylene mold and dry and cure in an oven at 80℃ for 24h to obtain the prepared high-temperature resistant color-changing polyurethane.

[0062] B3. According to the weight, mix 40 parts of high-temperature resistant color-changing polyurethane, 5 parts of silicone leveling agent, 5 parts of silicone defoamer and 50 parts of water to obtain a mixture; then add 10 parts of sheep bark foaming powder to the above mixture and stir evenly to obtain the prepared mixture.

[0063] Example 7

[0064] This embodiment provides a preparation process for velvety color-changing sheepskin, including the following steps:

[0065] S1. The mixture prepared in Example 4 was foamed at 120°C for 8 seconds to obtain a semi-finished sheepskin leather product. The semi-finished sheepskin leather product was transferred to an ultraviolet radiometer for ultraviolet irradiation. The wavelength of the light source used for ultraviolet irradiation was 365 nm, and the intensity of the ultraviolet irradiation was 0.6 W / m. 2 The ultraviolet irradiation time is 5 minutes to form a modified sheepskin semi-finished product.

[0066] S2. Apply the coating composition prepared in Example 1 to the surface of the modified sheepskin semi-finished product to form a 1.5 mm film layer, then dry it at 60°C for 5 minutes and let it cool naturally to room temperature to obtain the prepared velvety color-changing sheepskin.

[0067] Example 8

[0068] This embodiment provides a preparation process for velvety color-changing sheepskin, including the following steps:

[0069] S1. The mixture prepared in Example 5 was foamed at 125°C for 10 seconds to obtain a semi-finished sheepskin leather product. The semi-finished sheepskin leather product was transferred to an ultraviolet radiometer for ultraviolet irradiation. The wavelength of the light source used for ultraviolet irradiation was 365 nm, and the intensity of the ultraviolet irradiation was 0.7 W / m. 2 The ultraviolet irradiation time is 8 minutes to form a modified sheepskin semi-finished product.

[0070] S2. Apply the coating composition prepared in Example 2 to the surface of the modified sheepskin semi-finished product to form a 1.8 mm film layer, then dry it at 65°C for 6 minutes and let it cool naturally to room temperature to obtain the prepared velvety color-changing sheepskin.

[0071] Example 9

[0072] This embodiment provides a preparation process for velvety color-changing sheepskin, including the following steps:

[0073] S1. The mixture prepared in Example 6 was foamed at 130°C for 12 seconds to obtain a semi-finished sheepskin leather product. The semi-finished sheepskin leather product was transferred to an ultraviolet radiometer for ultraviolet irradiation. The wavelength of the light source used for ultraviolet irradiation was 365 nm, and the intensity of ultraviolet irradiation was 0.8 W / m. 2The ultraviolet irradiation time is 10 minutes to form a modified sheepskin semi-finished product.

[0074] S2. Apply the coating composition prepared in Example 3 to the surface of the modified sheepskin semi-finished product to form a 2 mm film layer, then dry it at 70°C and let it cool naturally to room temperature to obtain the prepared velvety color-changing sheepskin.

[0075] Comparative Example 1

[0076] Compared to Example 9, in this comparative example, step A2 was omitted when preparing the coating composition, and an equal mass of waterborne acrylic resin coating was used to replace the prepared crosslinked emulsion.

[0077] Comparative Example 2

[0078] Compared to Example 9, in this comparative example, step B1 was omitted when preparing the mixture, and the polymer chain extender was replaced with an equal mass of 3,5-diethyl-2,4-toluenediamine.

[0079] Comparative Example 3

[0080] Compared to Example 9, in this comparative example, no colorant was added during the preparation of the product in step B2; and 5g of colorant was added during the preparation of the mixture in step B3.

[0081] Performance testing: 1. Under the conditions of 25℃ and 55%RH, the gloss of the velvety color-changing sheepskin prepared in Examples 7-9 and Comparative Examples 1-3 was measured at 60℃ using a gloss meter; for all samples, three points were taken on the surface coating for measurement and the average value was taken.

[0082] 2. Take 10 mg of the velvety, color-changing sheepskin prepared in Examples 7-9 and Comparative Examples 1-3 as samples. The thermal decomposition temperature of the samples was analyzed sequentially using a thermogravimetric analyzer under a nitrogen atmosphere; the temperature was increased from 25℃ to 800℃ at a rate of 10℃ / min.

[0083] 3. The velvety, color-changing sheepskin prepared in Examples 7-9 and Comparative Examples 1-3 were cut into 10cm × 10cm samples. The samples were subjected to tensile testing using an electronic universal tensile test at a speed of 300mm / min. The tensile strength and elongation at break of the prepared samples were measured. The specific test results are shown in Table 1.

[0084] Table 1. Sample Performance Test Data

[0085] Group Project Example 7 Example 8 Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3 60℃ gloss / (GU) 15 18 21 7 18 20 Thermal decomposition temperature (°C) 341 355 365 361 320 362 Tensile strength (MPa) 36 39 40 38 30 40 Elongation at break (%) 667 701 725 715 610 715

[0086] Data Analysis: The coating compositions prepared in Examples 7-9 of this invention exhibit good film-forming properties and high gloss. The suede-like color-changing sheepskin prepared in Examples 7-9 all exhibit a semi-matte gloss at 60°. However, in Comparative Example 1, isobutyl acrylate was not added to the prepared coating composition. Isobutyl acrylate can further enhance the film-forming properties and gloss of the waterborne acrylic resin coating through crosslinking reactions. Therefore, the sheepskin prepared in Comparative Example 1 has a GU value of less than 10 and is in a matte state. Thus, compared to Comparative Example 1, when the coating compositions in Examples 7-9 are applied to the modified sheepskin semi-finished product, they can form suede-like color-changing sheepskin with a moderate film thickness and good gloss.

[0087] According to the data in Table 1, the suede-like color-changing sheepskin prepared in Examples 7-9 of this invention exhibits excellent thermal stability and a high thermal decomposition temperature. The suede-like color-changing sheepskin prepared in Examples 7-9 also shows good mechanical properties, characterized by high tensile strength and elongation at break. However, in Comparative Example 2, the same mass of 3,5-diethyl-2,4-toluenediamine was used to replace the prepared polymeric chain extender; the addition polymerization of pyromellitic anhydride and 3,5-diethyl-2,4-toluenediamine, utilizing their own benzene ring groups, helps to improve the tensile strength and elongation at break values ​​of the prepared polymeric chain extender. Therefore, the suede-like color-changing sheepskin prepared in Comparative Example 2 exhibits poorer mechanical properties, characterized by a decrease in tensile strength and elongation at break. Furthermore, the addition of the polymeric chain extender significantly improves the thermal stability of the prepared suede-like color-changing sheepskin. Therefore, the thermal decomposition temperature of the suede-like color-changing sheepskin prepared in Comparative Example 2 is also significantly reduced.

[0088] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0089] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0090] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A process for the production of a suede-like, colour-changing goatskin leather, characterised in that, The method comprises the following steps: S1, the mixture is foamed to obtain a sheep leather semi-finished product; the sheep leather semi-finished product is irradiated by ultraviolet light to form a modified sheep leather semi-finished product; S2, the coating composition is scraped onto the surface of the modified sheep leather semi-finished product to form a film layer, and then the film layer is dried and cooled to obtain the prepared sheep leather with a velvet touch and color change.

2. The method for preparing a velvety, color-changing sheepskin leather according to claim 1, characterized in that, In step S1, the preparation method of the mixture comprises the following steps: B1, pyrrolidone is added into pyromellitic anhydride, and the temperature is increased to 30-35 DEG C, and the pyromellitic anhydride is fully stirred until the pyromellitic anhydride is completely dissolved; then 3, 5-diethyl-2, 4-toluene diamine is added to obtain a reaction system; the reaction system is heated to 80-90 DEG C, and the reaction is continued at the temperature for 4-6 hours; after post-process treatment, a polymeric chain extender is prepared; B2, 1, 4-butanediol, dibutyltin dilaurate and N, N-dimethylacetamide are uniformly mixed to obtain component A; isophorone diisocyanate is dissolved in N, N-dimethylacetamide to obtain component B; component B is added dropwise into component A, and the temperature is increased to 75-85 DEG C, and the reaction is continued at the temperature for 2-3 hours; then the polymeric chain extender and the colorant are added, and the temperature is decreased to 70-75 DEG C, and the reaction is continued at the temperature for 6-8 hours to obtain a product; the product is solidified to obtain the prepared high-temperature-resistant color-changing polyurethane; B3, the high-temperature-resistant color-changing polyurethane, the silicone leveling agent, the silicone defoaming agent and water are mixed and stirred to obtain a mixture; the sheep foaming powder is added into the mixture and stirred uniformly to obtain the prepared mixture.

3. The method of claim 2, wherein the suede color-changing sheepskin leather is prepared by the steps of: In step B1, the amount ratio of N-methyl pyrrolidone, pyromellitic anhydride and 3, 5-diethyl-2, 4-toluene diamine is 200-300 mL: 10-20 g: 20-40 mL.

4. The method for preparing a velvety, color-changing sheepskin leather according to claim 2, characterized in that, In step B2, the amount ratio of 1, 4-butanediol, dibutyltin dilaurate and N, N-dimethylacetamide is 10-20 mL: 0.1-0.5 g: 10-20 mL; the amount ratio of component A, component B and the polymeric chain extender is 30-40 mL: 20-40 mL: 5-10 g; in step B3, the weight ratio of the high-temperature-resistant color-changing polyurethane, the silicone leveling agent, the silicone defoaming agent, water and the sheep foaming powder is 30-40: 2-5: 2-5: 40-50: 5-10.

5. The method for preparing a velvety, color-changing sheepskin leather according to claim 1, characterized in that, In step S1, the foaming temperature is 120-130℃, the foaming time is 8-12s; the wavelength of ultraviolet irradiation is 365nm, the intensity of external irradiation is 0.6-0.8W / m 2 , the time of ultraviolet irradiation is 5-10min.

6. The method of claim 1, wherein the suede variable color sheepskin leather is characterized by, In step S1, the preparation method of the coating composition comprises the following steps: A1, methyltrichlorosilane, deionized water and n-butanol are uniformly mixed, and the reaction is carried out in a closed system; after standing and layering, the organic layer liquid is collected to obtain the prepared low-crosslinking-degree cyclic siloxane; A2, the water-based acrylic resin coating, the potassium persulfate solution and the isobutyl acrylate are uniformly mixed to form a mixed system; the mixed system is heated to 70-80 DEG C, and the reaction is continued at the temperature for 30-60 minutes to obtain a crosslinked emulsion; A3, the crosslinked emulsion, the fly ash floating bead microbead and the low-crosslinking-degree cyclic siloxane are uniformly mixed to obtain the prepared coating composition.

7. The method of claim 6, wherein the suede variable color sheepskin leather is prepared by the steps of: The ratio of methyltrichlorosilane, deionized water and n-butanol in step A1 is 15-25 mL:20-30 mL:3-7 mL; the ratio of aqueous acrylic resin paint, potassium persulfate solution and isobutyl acrylate in step A2 is 100-120 mL:5-10 mL:5-10 mL.

8. The method of claim 6, wherein the suede variable color sheepskin leather is characterized by, The weight ratio of crosslinking emulsion, isobutyl acrylate and low crosslinking degree cyclic siloxane in step A3 is 100-120:5-10:3-10.

9. The method of claim 1, wherein the suede variable color sheepskin leather is characterized by, The film layer thickness is 1.5-2 mm; the drying temperature is 60-70 DEG C, and the drying time is 5-10 min.

10. A suede color-changing goatskin characterized in that, The preparation method is prepared by using the preparation method of the suede color-changing sheep leather according to any one of claims 1-9.

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