Alkali decrement production process of waterborne polyurethane microfiber synthetic leather

Abstract

The invention provides an alkali decrement production process of waterborne polyurethane microfiber synthetic leather, which is used for preparing the waterborne polyurethane microfiber leather through impregnation, alkali treatment, acid treatment and fat liquoring processes. The alkali deweighting regulator is designed and prepared in the alkali treatment link, so that splitting of the microfiber leather base cloth is more uniform and thorough, and the microfiber leather finally produced is good in comprehensive performance through matched treatment of the acid treatment and the fat liquoring process.

Description

Technical Field

[0001] The invention relates to the field of leather, and in particular to an alkali reduction production process for waterborne polyurethane ultra-fiber synthetic leather. Background Art

[0002] Ultrafine fiber polyurethane synthetic leather (ultrafine leather) is a new generation of synthetic leather developed in recent years. It is made of ultrafine fiber staple fibers through carding and needle punching to form a three-dimensional structure network non-woven fabric, and then finally made through polyurethane resin impregnation, fiber opening, leather grinding, dyeing and finishing. Ultrafine leather is superior to natural leather in mechanical strength, chemical corrosion resistance, biological resistance, and adaptability to automated cutting and processing. At the same time, it has the advantages of high strength, light weight, and good shape retention compared to natural leather.

[0003] After fiber opening, the microfiber leather has better air permeability and moisture permeability, and feels softer. However, fiber opening is generally treated with strong alkali such as sodium hydroxide. Although the concentration of the alkali solution will be diluted and controlled, long-term immersion will still destroy the polyurethane component in the microfiber leather. In addition, the alkali treatment process generally needs to be carried out under high temperature conditions and requires long-term immersion. This process consumes a lot of energy and often causes uneven dissolution, resulting in etching, which ultimately causes problems such as uneven subsequent dyeing of the microfiber leather. In addition, soft and comfortable feel and good air permeability and moisture permeability are the basic requirements for microfiber leather used in furniture and clothing. Fatting the base fabric after alkali treatment can obtain a softer and more breathable microfiber leather. However, the effect of general greasing treatment will also be poor due to process problems.

[0004] The production process of microfiber leather is a complete production line. Each process will be affected by the pre- and post-processing. Therefore, it is necessary to design the process from the overall perspective to obtain the desired microfiber leather. Summary of the invention

[0005] In view of the above problems in the prior art, the technical problem to be solved by the present invention is to provide an alkali reduction production process for water-based polyurethane microfiber synthetic leather, the purpose of which is to improve the utilization rate of alkali solution, shorten the alkali treatment time, and reduce the alkali treatment temperature, thereby reducing the adverse effects of alkali solution on polyurethane.

[0006] The technical solution of the present invention is as follows: An alkali reduction production process for waterborne polyurethane ultra-fiber synthetic leather comprises the following steps: (1) Impregnation: Prepare an aqueous polyurethane emulsion, stir it on a stirrer at 400-500 rpm for 30-50 min to obtain an aqueous polyurethane padding solution, immerse the microfiber leather base fabric in the aqueous polyurethane padding solution, and after sufficient impregnation, pass it through a padder with a pressure of 0.5-0.7 MPa, two immersions and two paddings (control the liquid carrying rate at 90%-110%), dry it at 120-140°C, and finally bake it at 145-155°C for 3-7 min to obtain an aqueous polyurethane microfiber leather base fabric; (2) Alkali treatment: adding an alkali reduction regulator to a sodium hydroxide solution to obtain an alkaline solution, placing the waterborne polyurethane microfiber leather base fabric treated in step (1) into the alkaline solution, treating at 60-80° C. for 30-60 min, with a bath ratio of 1:(25-35), taking out and squeezing and washing with water for 3-5 times to obtain a waterborne polyurethane microfiber leather; (3) Acid treatment: The waterborne polyurethane microfiber leather treated in step (2) is subjected to padding treatment with an acid solution at 30-40° C. for 5-10 min, with a bath ratio of 1:(15-25), and then extruded to adjust the pH to 4-5; (4) Fatting: placing the waterborne polyurethane microfiber leather treated in step (3) into a fatting solution, heating it to 40-50° C., and drying it at 90-110° C. after 0.5-1.5 h to obtain the microfiber leather.

[0007] Preferably, the base fabric used in this process is a sea-island type microfiber leather non-woven fabric.

[0008] Preferably, the aqueous polyurethane padding solution in step (1) consists of 100 parts of aqueous polyurethane, 1 to 4 parts of penetrant, 1 to 5 parts of cross-linking agent and 1 to 2 parts of leveling agent, and the added penetrant is one of penetrant JFC, penetrant JFC-1, penetrant JFC-2 and penetrant JFC-E.

[0009] Preferably, the solid content of the aqueous polyurethane padding solution used in step (1) is 15-20%.

[0010] Preferably, the amount of sodium hydroxide added to the alkaline solution in step (2) is 10 g / L to 15 g / L, and the amount of the alkali reduction regulator added is 0.5 g / L to 1 g / L.

[0011] Preferably, the acid solution in step (3) is prepared from an organic acid and water, wherein the organic acid is one of glacial acetic acid, salicylic acid, and citric acid, and the mass ratio of the organic acid to water is 1:(5-10).

[0012] Preferably, the fatliquor in step (4) is prepared from a fatliquor and water, wherein the fatliquor is one of phosphated oil, sulfited oil, and sulfonated oil, and the mass ratio of the fatliquor to water is 1:(3-9).

[0013] Preferably, the alkali reduction regulator is prepared by compounding component A and component B, component A is one of copper acetate and ferric formate, component B is one of hexadecyltrimethylammonium bromide (HDTMAB), hexadecylpyridinium chloride (HDPC), hexadecyltrimethylammonium chloride (HDTMAC) and octadecyldimethylbenzyl ammonium chloride, and the mass ratio of component A to component B is 1:(2~3).

[0014] Compared with the prior art, the present invention has the following beneficial effects: The invention adds a limited alkali reduction regulator during the alkali treatment process, which is conducive to the uniform effect of NaOH on the base fabric, alleviates the phenomenon that the fiber surface is etched by NaOH after fiber opening, and the regulator can improve the utilization rate of NaOH, thereby shortening the alkali treatment process time and reducing the temperature required for alkali reduction, while reducing the adverse effects of alkali solution on polyurethane, improving production efficiency and reducing energy consumption. In addition, acid treatment is conducive to the subsequent fatliquor infiltration into the base fabric, increasing the softness of the microfiber leather.

[0015] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] none DETAILED DESCRIPTION The present invention is specifically described below by way of examples, which are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. It should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

[0017] Example 1 The alkali reduction production process of a water-based polyurethane microfiber synthetic leather: (1) Impregnation: 2 parts of penetrant JFC, 3 parts of cross-linking agent and 1 part of leveling agent are added to 100 parts of waterborne polyurethane in sequence, and stirred on a stirrer at 450 rpm for 40 min to obtain a waterborne polyurethane padding solution, and the waterborne polyurethane padding solution is diluted with water to a solid content of 18%, and then the microfiber leather base fabric is immersed in the waterborne polyurethane padding solution. After being fully impregnated, it is passed through a padder with a pressure of 0.6 MPa, and after two immersions and two paddings (the liquid carrying rate is controlled at 90% to 110%), it is dried at 130°C, and finally baked at 150°C for 5 min to obtain a waterborne polyurethane microfiber leather base fabric; (2) Alkali treatment: dissolving 13 g of sodium hydroxide in 1 L of water to obtain a sodium hydroxide solution, mixing 1 g of copper acetate and 2.5 g of octadecyl dimethyl benzyl ammonium chloride to obtain an alkali reduction regulator, adding 0.8 g of the alkali reduction regulator to 1 L of the sodium hydroxide solution to obtain an alkali solution, placing the waterborne polyurethane microfiber leather base fabric treated in step (1) into the alkali solution, treating at 70° C. for 45 min, with a bath ratio of 1:30, taking out and squeezing and washing with water for 4 times to obtain a waterborne polyurethane microfiber leather; (3) Acid treatment: dissolving 100 g of glacial acetic acid in 800 g of water to obtain an acid solution, and padding the waterborne polyurethane microfiber leather treated in step (2) with the acid solution at 35° C. for 8 min, with a bath ratio of 1:20. After treatment, the leather is extruded to adjust the pH to 4.5; (4) Fatting: Add 100 g of phosphorylated oil to 600 g of water and stir evenly to obtain a fatting solution. Place the waterborne polyurethane microfiber leather treated in step (3) into the fatting solution, heat to 45° C., and dry at 100° C. after 1 hour to obtain the microfiber leather.

[0018] Example 2 The alkali reduction production process of a water-based polyurethane microfiber synthetic leather: (1) Impregnation: 1 part of penetrant JFC-1, 1 part of cross-linking agent and 1 part of leveling agent were added to 100 parts of waterborne polyurethane in sequence, and stirred on a stirrer at 400 rpm for 30 min to obtain a waterborne polyurethane padding solution, and the waterborne polyurethane padding solution was diluted with water to a solid content of 15%, and then the microfiber leather base fabric was immersed in the waterborne polyurethane padding solution. After being fully impregnated, it was passed through a padder with a pressure of 0.5 MPa, and after two immersions and two paddings (the liquid carrying rate was controlled at 90% to 110%), it was dried at 120°C, and finally baked at 145°C for 3 min to obtain a waterborne polyurethane microfiber leather base fabric; (2) Alkali treatment: dissolving 10 g of sodium hydroxide in 1 L of water to obtain a sodium hydroxide solution, mixing 1 g of ferric formate and 2 g of hexadecyltrimethylammonium bromide (HDTMAB) to obtain an alkali reduction regulator, adding 0.5 g of the alkali reduction regulator to 1 L of the sodium hydroxide solution to obtain an alkali solution, placing the waterborne polyurethane microfiber leather base fabric treated in step (1) into the alkali solution, treating at 60° C. for 60 min, with a bath ratio of 1:25, taking out and squeezing and washing with water for 3 times to obtain a waterborne polyurethane microfiber leather; (3) Acid treatment: dissolving 100 g of salicylic acid in 500 g of water to obtain an acid solution, and padding the waterborne polyurethane microfiber leather treated in step (2) with the acid solution at 30° C. for 5 min, with a bath ratio of 1:15. After treatment, the leather is extruded to adjust the pH to 4; (4) Fatting: Add 100 g of sulfited oil to 300 g of water and stir evenly to obtain a fatting solution. Place the aqueous polyurethane microfiber leather treated in step (3) into the fatting solution, heat to 40° C., and dry at 90° C. after 0.5 h to obtain the microfiber leather.

[0019] Example 3 The alkali reduction production process of a water-based polyurethane microfiber synthetic leather: (1) Impregnation: 4 parts of penetrant JFC-E, 5 parts of cross-linking agent and 2 parts of leveling agent were added to 100 parts of waterborne polyurethane in sequence, stirred at 500 rpm for 50 min on a stirrer to obtain a waterborne polyurethane padding solution, diluted the waterborne polyurethane padding solution with water to a solid content of 20%, and the microfiber leather base fabric was immersed in the waterborne polyurethane padding solution. After being fully impregnated, the base fabric was passed through a padder with a pressure of 0.7 MPa, and after two immersions and two paddings (the liquid carrying rate was controlled at 90% to 110%), the base fabric was dried at 140°C, and finally baked at 155°C for 7 min to obtain a waterborne polyurethane microfiber leather base fabric; (2) Alkali treatment: dissolving 15 g of sodium hydroxide in 1 L of water to obtain a sodium hydroxide solution, mixing 1 g of copper acetate and 3 g of hexadecyltrimethylammonium chloride (HDTMAC) to obtain an alkali reduction regulator, adding 1 g of the alkali reduction regulator to 1 L of the sodium hydroxide solution to obtain an alkali solution, placing the waterborne polyurethane microfiber leather base fabric treated in step (1) into the alkali solution, treating at 80° C. for 30 min, with a bath ratio of 1:35, taking out and squeezing and washing with water for 5 times to obtain a waterborne polyurethane microfiber leather; (3) Acid treatment: dissolving 100 g of citric acid in 1000 g of water to obtain an acid solution, and padding the waterborne polyurethane microfiber leather treated in step (2) with the acid solution at 40° C. for 10 min, with a bath ratio of 1:25. After treatment, the leather is extruded to adjust the pH to 5; (4) Fatting: Add 100 g of sulfonated oil to 900 g of water and stir evenly to obtain a fatting solution. Place the water-based polyurethane microfiber leather treated in step (3) into the fatting solution, heat to 50° C., and dry at 110° C. after 1.5 hours to obtain the microfiber leather.

[0020] Comparative Example 1 An alkali reduction production process for water-based polyurethane ultra-fiber synthetic leather without adding an alkali reduction regulator: (1) Impregnation: same as in Example 1; (2) Alkali treatment: dissolving 13 g of sodium hydroxide in 1 L of water to obtain a sodium hydroxide solution, placing the waterborne polyurethane microfiber leather base fabric treated in step (1) into the sodium hydroxide solution, treating at 70° C. for 45 min, with a bath ratio of 1:30, taking out and squeezing and washing with water for 4 times to obtain a waterborne polyurethane microfiber leather; (3) Acid treatment: same as in Example 1; (4) Fat addition: Same as Example 1.

[0021] Comparative Example 2 A alkali reduction production process for waterborne polyurethane microfiber synthetic leather: (1) Impregnation: same as in Example 1; (2) Alkali treatment: same as in Example 1; (3) Neutralization treatment: dissolving 100 g of glacial acetic acid in 800 g of water to obtain an acid solution, and padding the waterborne polyurethane microfiber leather treated in step (2) with the acid solution at 35° C. for 8 min, with a bath ratio of 1:20. After treatment, the leather is extruded to adjust the pH to 7; (4) Fat addition: Same as Example 1.

[0022] Comparative Example 3 A alkali reduction production process for waterborne polyurethane microfiber synthetic leather: (1) Impregnation: same as in Example 1; (2) Alkali treatment: dissolving 13 g of sodium hydroxide in 1 L of water to obtain a sodium hydroxide solution, adding 0.8 g of dodecyltrimethylammonium bromide (DDTMAB) to the 1 L of sodium hydroxide solution to obtain an alkaline solution, placing the waterborne polyurethane microfiber leather base fabric treated in step (1) into the alkaline solution, treating at 70° C. for 45 min, with a bath ratio of 1:30, taking out and squeezing and washing with water for 4 times to obtain a waterborne polyurethane microfiber leather; (3) Acid treatment: same as in Example 1; (4) Fat addition: Same as Example 1.

[0023] Experimental methods The embodiments and comparative examples were tested, and the test methods for the softness, air permeability, moisture permeability, alkali reduction rate and mechanical properties of the microfiber leather were as follows: 1. Softness test: The softness of the microfiber leather of Examples 1 to 3 and Comparative Examples 1 to 2 was measured using the GT-303 leather softness tester: the microfiber leather was cut into the required rectangular fabric samples and then placed on the instrument base. The pressing handle was first folded down to fully retract the probe, and the base fabric was clamped between the clamps. The upper arm was locked, and the pointer rotated after the hand was released. After the pointer stabilized, the pointer reading was read.

[0024] 2. Air permeability test: The air permeability of the sample is tested according to GB / T24218.15-2018 "Test methods for nonwoven fabrics for textiles - Part 15: Determination of air permeability".

[0025] 3. Moisture permeability test: Test the moisture permeability of samples according to GB / T12704.1-2009 “Test method for moisture permeability of textile fabrics Part 2: Evaporation method”.

[0026] 4. Alkali weight loss rate: the time required for the alkali weight loss of the microfiber leather of test examples 1 to 3 and comparative examples 1 to 2 to reach a weight loss rate of 15%.

[0027] 5. Mechanical properties test: According to GB / T24218.3-2010 "Test methods for textile nonwoven materials Part 3: Determination of breaking strength and elongation at break (strip method)", the tensile breaking properties of the samples were tested.

[0028] Table 1 shows the performance test results of the microfiber leather produced in Examples 1 to 3 and Comparative Examples 1 to 3. It can be seen from the weight loss rate data of the microfiber leather in the table that the time required for the weight loss of 15% in Examples 1 to 3 and Comparative Example 2 is lower than that in Comparative Examples 1 and 3, indicating that the alkali reduction regulator selected in the present invention can increase the fiber opening rate, and the effect is better than that of the ordinary regulating promoter (Comparative Example 3). The reason may be that the alkali reduction regulator in Examples 1 to 3 can be adsorbed on the surface of the microfiber leather fiber through electrostatic action, so that the surface of the microfiber leather is positively charged, which is conducive to attracting hydroxyl ions in sodium hydroxide, thereby accelerating the fiber opening rate. The increase in the fiber opening rate can not only achieve the required fiber opening rate in a short time, improve production efficiency, but also reduce energy consumption and save costs.

[0029] The fiber opening rate will affect the fiber opening degree of the microfiber leather under the same alkali treatment time, and then affect the various properties of the microfiber leather. According to the test data in Table 1, the fiber opening degree of Examples 1 to 3 is higher, and its air permeability and moisture permeability are better. In addition, by observing the softness data in Table 1, it can be seen that the softness of Examples 1 to 3 is higher than that of Comparative Examples 1 to 3. This may be due to the insufficient fiber opening degree of Comparative Examples 1 and 3, and the microfiber leather finally obtained is not soft enough; the softness of Comparative Example 2 is significantly lower than that of Examples 1 to 3, which may be due to the presence of a large number of amino ions on the surface of the water-based polyurethane microfiber leather after acid treatment of Examples 1 to 3. The fatting agent selected by the present invention is an anionic fatting agent, which has a stronger binding property with the amino ions on the leather surface, so that the fatting agent has better permeability on the water-based polyurethane microfiber leather, thereby improving the softness of the microfiber leather.

[0030] By observing the breaking strength and breaking elongation of Examples 1 to 3 and Comparative Examples 1 to 3, it can be seen that the degree of fiber opening and the fatliquor have a certain influence on the mechanical properties of the microfiber leather. Specifically, the degree of fiber opening in Comparative Example 1 is obviously insufficient due to the absence of an alkali reduction regulator, and the final mechanical properties are relatively high; Comparative Example 2 is not acid-treated, and the fatliquor cannot completely penetrate into the microfiber leather, resulting in a decrease in mechanical properties; Comparative Example 3 cannot achieve uniform fiber opening due to the use of ordinary regulators in the alkali treatment, and the fiber surface will be etched, which has an adverse effect on the mechanical properties of the microfiber leather.

[0031] In summary, the water-based polyurethane microfiber leather produced by the process adopted in the present invention has uniform fiber opening and, in terms of softness, air permeability, moisture permeability and mechanical properties, the comprehensive performance of the microfiber leather of the present invention is good.

[0032] Table 1: Performance test of microfiber leather produced in Examples 1 to 3 and Comparative Examples 1 to 3 The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all included in the protection scope of the present invention.

Claims

1. An alkali reduction production process for waterborne polyurethane microfiber synthetic leather, characterized in that: The following steps are involved: (1) Impregnation: Prepare an aqueous polyurethane emulsion, stir it on a stirrer at 400-500 rpm for 30-50 min to obtain an aqueous polyurethane padding solution, immerse the microfiber leather base fabric in the aqueous polyurethane padding solution, and after sufficient impregnation, pass it through a padder with a pressure of 0.5-0.7 MPa, two immersions and two paddings (control the liquid carrying rate at 90%-110%), dry it at 120-140°C, and finally bake it at 145-155°C for 3-7 min to obtain an aqueous polyurethane microfiber leather base fabric; (2) Alkali treatment: adding an alkali reduction regulator to a sodium hydroxide solution to obtain an alkaline solution, placing the waterborne polyurethane microfiber leather base fabric treated in step (1) into the alkaline solution, treating at 60-80° C. for 30-60 min, with a bath ratio of 1:(25-35), taking out and squeezing and washing with water for 3-5 times to obtain a waterborne polyurethane microfiber leather; (3) Acid treatment: The waterborne polyurethane microfiber leather treated in step (2) is subjected to padding treatment with an acid solution at 30-40° C. for 5-10 min, with a bath ratio of 1:(15-25), and then extruded to adjust the pH to 4-5; (4) Fatting: placing the waterborne polyurethane microfiber leather treated in step (3) into a fatting solution, heating it to 40-50° C., and drying it at 90-110° C. after 0.5-1.5 h to obtain the microfiber leather.

2. The alkali reduction production process of waterborne polyurethane ultra-fiber synthetic leather according to claim 1, characterized in that: The base fabric used in this process is sea-island type microfiber leather non-woven fabric.

3. The alkali reduction production process of waterborne polyurethane ultra-fiber synthetic leather according to claim 1, characterized in that: The aqueous polyurethane padding solution in step (1) is composed of 100 parts of aqueous polyurethane, 1 to 4 parts of penetrant, 1 to 5 parts of cross-linking agent and 1 to 2 parts of leveling agent, and the added penetrant is one of penetrant JFC, penetrant JFC-1, penetrant JFC-2 and penetrant JFC-E.

4. The alkali reduction production process of waterborne polyurethane ultra-fiber synthetic leather according to claim 1, characterized in that: The solid content of the aqueous polyurethane padding solution used in step (1) is 15-20%.

5. The alkali reduction production process of waterborne polyurethane ultra-fiber synthetic leather according to claim 1, characterized in that: The amount of sodium hydroxide added to the alkaline solution in step (2) is 10 g / L to 15 g / L, and the amount of the alkali reduction regulator added is 0.5 g / L to 1 g / L.

6. The alkali reduction production process of waterborne polyurethane ultra-fiber synthetic leather according to claim 1, characterized in that: In step (3), the acid solution is prepared from an organic acid and water, wherein the organic acid is one of glacial acetic acid, salicylic acid, and citric acid, and the mass ratio of the organic acid to water is 1:(5-10).

7. The alkali reduction production process of waterborne polyurethane ultra-fiber synthetic leather according to claim 1, characterized in that: The fat-liquor solution in step (4) is prepared from a fat-liquor agent and water, wherein the fat-liquor agent is one of phosphated oil, sulfited oil, and sulfonated oil, and the mass ratio of the fat-liquor agent to water is 1: (3-9).

8. The alkali reduction production process of waterborne polyurethane ultra-fiber synthetic leather according to claim 4, characterized in that: The alkali reduction regulator is prepared by compounding component A and component B, wherein component A is one of copper acetate and ferric formate, and component B is one of hexadecyltrimethylammonium bromide (HDTMAB), hexadecylpyridinium chloride (HDPC), hexadecyltrimethylammonium chloride (HDTMAC) and octadecyldimethylbenzyl ammonium chloride, and the mass ratio of component A to component B is 1:(2~3).

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