A kind of water-based polyurethane emulsion for microfiber leather, anti-crack microfiber leather

Abstract

The application discloses a kind of water-based polyurethane emulsion for microfiber leather, raw materials include by weight portion: diisocyanate 17-20 parts, polyether polyol 55-60 parts, hydrophilic chain extender 1.5-1.7 parts, dendritic polyamide-amine 3-4 parts, small molecule chain extender 0.4-0.6 parts, amine chain extender 0.8-1.2 parts, catalyst 0.008-0.01 parts, water 160-180 parts;Among them, dendritic polyamide-amine is ethylenediamine as core, dendritic polyamide-amine end group is amino, branching algebra is 0.0.The application also discloses the preparation method of the above-mentioned water-based polyurethane emulsion for microfiber leather.The application also discloses a kind of anti-cracking microfiber leather and preparation method thereof.The application can avoid water-based polyurethane loss when alkali reduction, water-based polyurethane is easy to migrate with water when drying, the problem of appearing middle empty core, can improve the hand feeling of microfiber leather;Microfiber leather has good crack resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microfiber leather, and particularly relates to a water-based polyurethane emulsion for microfiber leather and anti-cracking microfiber leather. BACKGROUND

[0002] Microfiber leather is made of non-woven fabric with three-dimensional network structure by using high molecular microfiber similar to the structure and performance of bundle-shaped collagen fiber in natural leather, and then filled with polyurethane and other substances through post-processing. Microfiber leather has soft luster, soft hand feeling and strong real leather feeling, and is the best substitute for natural leather, and is widely used in the fields of automobile interior, high-grade sneakers and home furnishing.

[0003] At present, most of the alkali-reduced microfiber leather adopts solvent-based polyurethane resin, but a large amount of solvent is used in the production process, polluting the environment and damaging the health of workers. With the requirements of environmental protection and employee health, water-based polyurethane is gradually applied in microfiber leather. However, when using water-based polyurethane in alkali reduction, a large amount of resin is easily lost, resulting in poor hand feeling of microfiber leather. In addition, the microfiber leather prepared by using water-based polyurethane is prone to cracking and has poor performance. Furthermore, after the water-based polyurethane is impregnated into the base cloth, the polyurethane emulsion migrates to both ends of the base cloth during drying, resulting in the problem of hollow core in the middle, and thus the hand feeling and performance of the microfiber leather are poor. SUMMARY

[0004] Based on the technical problems in the background art, the present application provides a water-based polyurethane emulsion for microfiber leather and anti-cracking microfiber leather. The water-based polyurethane emulsion can avoid the problems of easy loss of water-based polyurethane during alkali reduction, easy migration of water-based polyurethane with water during drying, and hollow core in the middle, thereby improving the hand feeling of microfiber leather. In addition, the obtained microfiber leather has good anti-cracking performance.

[0005] The present application provides a water-based polyurethane emulsion for microfiber leather, and the raw materials thereof include, by weight, 17-20 parts of diisocyanate, 55-60 parts of polyether polyol, 1.5-1.7 parts of hydrophilic chain extender, 3-4 parts of dendritic polyamide-amine, 0.4-0.6 parts of small molecule chain extender, 0.8-1.2 parts of amine chain extender, 0.008-0.01 parts of catalyst and 160-180 parts of water.

[0006] The dendritic polyamide-amine has ethylenediamine as the core, the end group of the dendritic polyamide-amine is amino, and the branching order is 0.0.

[0007] Preferably, the dendritic polyamide-amine has the structural formula as shown in formula (I):

[0008]

[0009] Dendrimeric polyamide-amine represented by formula (I) can be purchased from the market, and its CAS number is 155773-72-1.

[0010] Preferably, the amine chain extender is one or more of 2-(3-aminophenyl)-5-aminobenzimidazole, 2-(4-aminophenyl)-5-aminobenzimidazole.

[0011] Preferably, the diisocyanate is an aliphatic diisocyanate.

[0012] Preferably, the polyether polyol is one or more of polyethylene glycol, polytetrahydrofuran.

[0013] Preferably, the hydrophilic chain extender is one or more of dimethylol propanoic acid, dimethylol butanoic acid.

[0014] Preferably, the small molecule chain extender is 1,4-butanediol.

[0015] The application also provides a preparation method of the above-mentioned water-based polyurethane emulsion for microfiber leather, comprising the following steps: mixing diisocyanate, polyether polyol, hydrophilic chain extender, and catalyst in an inert gas atmosphere, and then performing reaction, then adding dendrimeric polyamide-amine to continue reaction, then adding small molecule chain extender to continue reaction, then adding organic solvent to reduce viscosity and adjust pH to neutral, then adding water to emulsify, then adding amine chain extender to continue reaction, then removing the organic solvent, and then obtaining the water-based polyurethane emulsion.

[0016] Preferably, the organic solvent is acetone.

[0017] Preferably, the pH is adjusted to neutral by using triethylamine.

[0018] Preferably, the diisocyanate, polyether polyol, hydrophilic chain extender, and catalyst are mixed and reacted at 50-60℃ for 0.5-1h.

[0019] Preferably, the dendrimeric polyamide-amine is added and the reaction is continued at 50-60℃ for 1-1.5h.

[0020] Preferably, the small molecule chain extender is added and the reaction is continued at 50-60℃ for 0.5-1h.

[0021] Preferably, the amine chain extender is added and the reaction is continued at room temperature for 0.5-1h.

[0022] The application also provides an anti-cracking microfiber leather, comprising: island fiber base cloth and the above-mentioned water-based polyurethane emulsion for microfiber leather.

[0023] The application further provides a preparation method of the anti-cracking microfiber leather, which comprises the following steps: taking the water-based polyurethane emulsion, adjusting the viscosity, then containing and soaking the island fiber base cloth, drying, performing reduction treatment with alkali water, washing with water, drying, and obtaining the anti-cracking microfiber leather.

[0024] Advantages:

[0025] The dendritic polyamide-amine with a specific structure is selected to participate in in-situ polymerization of the polyurethane, so that the polyurethane is formed into an interlinked network structure, the mechanical property is improved, the problem of easy loss of the polyurethane during alkali reduction and the problem of poor hand feeling of the microfiber leather are avoided, the stability of the polyurethane is improved, the problem of easy migration of the polyurethane with water during drying and the problem of hollow core are avoided, and the anti-cracking property of the microfiber leather is improved; in addition, 2-(3-aminophenyl)-5-aminobenzimidazole and 2-(4-aminophenyl)-5-aminobenzimidazole are selected as the chain extender, a large number of amino groups and imidazole groups are introduced, the amino groups and imidazole groups are matched with the multiple amide groups and isocyanate groups and hydroxyl groups in the dendritic polyamide-amine to form amide groups, a large number of hydrogen bonds are formed between the polyurethane and the island fiber base cloth, the polyurethane is fixed, the problems of easy loss of the polyurethane and hollow core are further avoided, and the hydrogen bonds in the polyurethane can greatly improve the anti-cracking property of the microfiber leather. DETAILED DESCRIPTION

[0026] The technical solutions of the application will be described in detail below through specific embodiments.

[0027] Embodiment 1

[0028] A water-based polyurethane emulsion for microfiber leather, raw materials of which include, by weight: isophorone diisocyanate 17 parts, polyethylene glycol 2000 55 parts, dimethylol propionic acid 1.7 parts, dendritic polyamide-amine with CAS number 155773-72-1 3 parts, 1,4-butanediol 0.6 parts, 2-(3-aminophenyl)-5-aminobenzimidazole 0.8 parts, organic bismuth catalyst 0.01 parts, and water 160 parts.

[0029] The preparation method of the water-based polyurethane for microfiber leather comprises the following steps: under a nitrogen atmosphere, isophorone diisocyanate, polyethylene glycol 2000, dimethylol propionic acid and an organic bismuth catalyst are uniformly mixed, and then reacted at 60℃ for 0.5h; then dendritic polyamide-amine is added, and the reaction is continued at 60℃ for 1h; then 1,4-butanediol is added, and the reaction is continued at 60℃ for 0.5h; then the temperature is lowered to room temperature, and acetone is added to reduce the viscosity; then triethylamine is added to adjust the pH to neutral; then water is added for emulsification; then 2-(3-aminophenyl)-5-aminobenzimidazole is added, and the reaction is continued at room temperature for 0.5h; then acetone is removed by reduced pressure distillation, and a water-based polyurethane emulsion is obtained.

[0030] Example 2

[0031] A water-based polyurethane emulsion for microfiber leather, raw materials of which include, by weight: isophorone diisocyanate 20 parts, polytetrahydrofuran 2000 60 parts, dimethylol butyric acid 1.5 parts, dendritic polyamide-amine with CAS number 155773-72-1 4 parts, 1,4-butanediol 0.4 parts, 2-(4-aminophenyl)-5-aminobenzimidazole 1.2 parts, organic bismuth catalyst 0.008 parts, water 180 parts.

[0032] The preparation method of the above-mentioned water-based polyurethane for microfiber leather includes the following steps: mixing isophorone diisocyanate, polytetrahydrofuran 2000, dimethylol butyric acid, and organic bismuth catalyst, and then reacting at 50°C for 1h, then adding dendritic polyamide-amine, and continuing to react at 50°C for 1.5h, then adding 1,4-butanediol, and continuing to react at 50°C for 1h, then cooling to room temperature, adding acetone to reduce viscosity, adjusting pH to neutral with triethylamine, adding water to emulsify, then adding 2-(4-aminophenyl)-5-aminobenzimidazole, and continuing to react at room temperature for 1h, and then removing acetone by vacuum distillation to obtain a water-based polyurethane emulsion.

[0033] Example 3

[0034] A water-based polyurethane emulsion for microfiber leather, raw materials of which include, by weight: isophorone diisocyanate 20 parts, polytetrahydrofuran 2000 30 parts, dimethylol butyric acid 1.6 parts, dendritic polyamide-amine with CAS number 155773-72-1 3.5 parts, 1,4-butanediol 0.5 parts, 2-(3-aminophenyl)-5-aminobenzimidazole 1 part, organic bismuth catalyst 0.009 parts, water 170 parts.

[0035] The preparation method of the above-mentioned water-based polyurethane for microfiber leather includes the following steps: mixing isophorone diisocyanate, polytetrahydrofuran 2000, dimethylol butyric acid, and organic bismuth catalyst, and then reacting at 50°C for 1h, then adding dendritic polyamide-amine, and continuing to react at 50°C for 1.5h, then adding 1,4-butanediol, and continuing to react at 50°C for 1h, then cooling to room temperature, adding acetone to reduce viscosity, adjusting pH to neutral with triethylamine, adding water to emulsify, then adding 2-(4-aminophenyl)-5-aminobenzimidazole, and continuing to react at room temperature for 1h, and then removing acetone by vacuum distillation to obtain a water-based polyurethane emulsion.

[0036] Comparative Example 1

[0037] Without dendritic polyamide-amine, the same as Example 3.

[0038] Comparative Example 2

[0039] The 2-(3-aminophenyl)-5-aminobenzimidazole is replaced by ethylenediamine, and the rest is the same as in Example 3.

[0040] Comparative Example 3

[0041] The dendritic polyamide-amine is not contained, and the 2-(3-aminophenyl)-5-aminobenzimidazole is replaced by ethylenediamine, and the rest is the same as in Example 3.

[0042] The polyurethane emulsions in Examples 1-3 and Comparative Examples 1-3 are used to prepare microfiber leathers in the same way, including the following steps: the aqueous polyurethane emulsion is adjusted to a viscosity of 3000 mPa·s with a thickening agent, then the sea-island fiber base cloth is immersed, dried at 120℃ for 30 min, then reduced in weight by immersing in a 10wt% sodium hydroxide aqueous solution at 90℃ for 30 min, washed with water, and dried to obtain the microfiber leather.

[0043] The microfiber leathers prepared in each group are detected for their properties, and the results are shown in Table 1.

[0044] Crack number: five 1cm 2 areas are taken on the surface of the microfiber leather, the number of cracks is counted after the same tension is applied, and the average value is calculated; then the microfiber leather is left to stand at room temperature for 4h, and the crack number in the same areas is counted again, and the average value is calculated.

[0045] Table 1 detection results

[0046]

[0047] As can be seen from Table 1, the microfiber leather prepared using the aqueous polyurethane emulsion described in the present application has a soft hand feeling, good flesh feeling, small resin loss, no empty core, and good crack resistance.

[0048] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and inventive concepts of the present application within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A water-based polyurethane emulsion for microfiber leather, characterized in that, The raw materials, by weight, include: 17-20 parts diisocyanate, 55-60 parts polyether polyol, 1.5-1.7 parts hydrophilic chain extender, 3-4 parts dendritic polyamide-amine, 0.4-0.6 parts small molecule chain extender, 0.8-1.2 parts amine chain extender, 0.008-0.01 parts catalyst, 160-180 parts water, and triethylamine; The structural formula of the dendritic polyamide-amine is shown in formula (I): Formula (I); The amine chain extender is one or more of 2-(3-aminophenyl)-5-aminobenzimidazole and 2-(4-aminophenyl)-5-aminobenzimidazole.

2. The waterborne polyurethane emulsion for microfiber leather according to claim 1, characterized in that, Diisocyanates are aliphatic diisocyanates.

3. The waterborne polyurethane emulsion for microfiber leather according to claim 1, characterized in that, The polyether polyol is one or more of polyethylene glycol and polytetrahydrofuran.

4. The waterborne polyurethane emulsion for microfiber leather according to claim 1, characterized in that, The hydrophilic chain extender is one or more of dimethylolpropionic acid and dimethylolbutyric acid.

5. The waterborne polyurethane emulsion for microfiber leather according to claim 1, characterized in that, The small molecule chain extender is 1,4-butanediol.

6. A method for preparing an aqueous polyurethane emulsion for microfiber leather as described in any one of claims 1-5, characterized in that, The process includes the following steps: In an inert gas atmosphere, diisocyanate, polyether polyol, hydrophilic chain extender, and catalyst are mixed and reacted. Then, dendritic polyamide-amine is added to continue the reaction. Small molecule chain extender is added to continue the reaction. Organic solvent is added to reduce viscosity and the pH is adjusted to neutral. Water is added to emulsify. Then, amine chain extender is added and the reaction continues. The organic solvent is removed to obtain an aqueous polyurethane emulsion.

7. The method for preparing the waterborne polyurethane emulsion for microfiber leather according to claim 6, characterized in that, The organic solvent is acetone.

8. The method for preparing the waterborne polyurethane emulsion for microfiber leather according to claim 6, characterized in that, Adjust the pH to neutral using triethylamine.

9. The method for preparing the waterborne polyurethane emulsion for microfiber leather according to claim 6, characterized in that, Mix diisocyanate, polyether polyol, hydrophilic chain extender and catalyst, and react at 50-60℃ for 0.5-1h.

10. The method for preparing the waterborne polyurethane emulsion for microfiber leather according to claim 6, characterized in that, Add dendritic polyamide-amine and continue the reaction at 50-60℃ for 1-1.5h.

11. The method for preparing the waterborne polyurethane emulsion for microfiber leather according to claim 6, characterized in that, Add a small molecule chain extender and continue the reaction at 50-60℃ for 0.5-1h.

12. The method for preparing the waterborne polyurethane emulsion for microfiber leather according to claim 6, characterized in that, Add an amine chain extender and continue the reaction at room temperature for 0.5-1 h.

13. A crack-resistant microfiber leather, characterized in that, include: The island fiber base fabric and the waterborne polyurethane emulsion of the microfiber leather as described in any one of claims 1-5.

14. A method for preparing the crack-resistant microfiber leather as described in claim 13, characterized in that, The process includes the following steps: taking the water-based polyurethane emulsion of microfiber leather as described in any one of claims 1-5, adjusting the viscosity, then impregnating the sea island fiber base fabric, drying, performing a weight reduction treatment with alkaline water, washing with water, and drying to obtain crack-resistant microfiber leather.

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