A waterborne polyurethane emulsion, a preparation method and application thereof

Abstract

The application discloses a kind of water-based polyurethane emulsion, raw material includes by weight portion: diisocyanate 20 parts, polyether polyol 50-55 parts, cyclodextrin 2-3 parts, hydrophilic chain extender 1.8-2.0 parts, modified silicon dioxide 2-3 parts, small molecule chain extender 0.4-0.6 parts, amine chain extender 1-1.2 parts, catalyst 0.01-0.012 parts, water 140-160 parts.The application also discloses the preparation method and application in microfiber leather of the above water-based polyurethane emulsion.The application also discloses a kind of polyamide microfiber leather and preparation method thereof.The polyamide microfiber leather described in the application has good hand feeling and air permeability, and good waterproofness.

Description

TECHNICAL FIELD

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

[0002] Microfiber leather is widely used in the fields of automobile interiors, high-grade sneakers and home furnishing. At present, the preparation process of microfiber leather is generally as follows: a base cloth with a three-dimensional network structure is made of nylon microfiber, and then polyurethane and other substances are filled and processed to obtain the microfiber leather.

[0003] With the improvement of environmental protection requirements, water-based polyurethane is gradually applied in microfiber leather. However, after the water-based polyurethane is impregnated into the base cloth, the polyurethane emulsion migrates to both ends of the base cloth during the drying process, resulting in an empty core in the middle, which makes the microfiber leather feel poor. In addition, a large amount of resin is easily lost during the alkali reduction, further reducing the feel of the microfiber leather. In addition, with the improvement of comfort requirements, higher requirements are put forward for the air permeability of microfiber leather. SUMMARY

[0004] Based on the technical problems in the background art, the present application provides a water-based polyurethane emulsion, a preparation method and application thereof. The polyamide microfiber leather has good feel and air permeability, and good waterproofness.

[0005] The present application provides a water-based polyurethane emulsion, and the raw materials thereof include, by weight, 20 parts of diisocyanate, 50-55 parts of polyether polyol, 2-3 parts of cyclodextrin, 1.8-2.0 parts of hydrophilic chain extender, 2-3 parts of modified silicon dioxide, 0.4-0.6 parts of small molecule chain extender, 1-1.2 parts of amine chain extender, 0.01-0.012 parts of catalyst and 140-160 parts of water.

[0006] Preferably, in the preparation process of the modified silicon dioxide, the silicon dioxide particles 1 with a particle size of 2-3 μm, the silicon dioxide particles 2 with a particle size of 50-100 nm, ethanol, ammonia water and water are uniformly dispersed and reacted to obtain the modified silicon dioxide, wherein the surface of the silicon dioxide particles 1 is grafted with epoxy groups, and the surface of the silicon dioxide particles 2 is grafted with amino groups.

[0007] Silane coupling agents containing epoxy groups or amino groups can be used to modify the surface of the silicon dioxide to obtain silicon dioxide particles grafted with epoxy groups or amino groups on the surface. The silane coupling agent is preferably gamma-glycidoxypropyltrimethoxysilane, gamma-aminopropyltriethoxysilane or the like.

[0008] This invention utilizes the covalent bonding of epoxy groups and amino groups to graft small-diameter silica particles onto the surface of large-diameter silica particles, giving the modified silica a micro / nano structure. When used in polyurethane emulsions, this modified silica improves the waterproof performance of leather. Furthermore, the modified silica surface has numerous amino groups that can covalently bond with isocyanate groups in polyurethane. By adjusting the amount of modified silica, it forms uniformly distributed micropores in the polyurethane emulsion. Combined with an appropriate amount of cyclodextrin, even more micropores are formed, significantly improving the breathability of microfiber leather. This results in microfiber leather possessing both excellent breathability and waterproof performance.

[0009] Preferably, in the preparation of modified silica, the weight ratio of silica particles 1 to silica particles 2 is 1:3.5-4.

[0010] Preferably, in the preparation process of modified silica, the weight ratio of silica particles 1 to ethanol, ammonia and water is 1:30-40:2-2.5:2.5-3.

[0011] Preferably, the modified silica is reacted at 70-75°C for 6-7 hours during the preparation process.

[0012] Preferably, the diisocyanate is isophorone diisocyanate.

[0013] Preferably, the polyether polyol is polytetrahydrofuran.

[0014] Preferably, the hydrophilic chain extender is dimethylolpropionic acid.

[0015] Preferably, the small molecule chain extender is 1,4-butanediol.

[0016] Preferably, the amine chain extender is triethylenetetramine.

[0017] The present invention also proposes a method for preparing the above-mentioned waterborne polyurethane emulsion, comprising the following steps: in an inert gas atmosphere, diisocyanate, polyether polyol, hydrophilic chain extender, cyclodextrin and catalyst are mixed and reacted, then modified silica is added to continue the reaction, then a small molecule chain extender is added to continue the reaction, an organic solvent is added to reduce viscosity and the pH is adjusted to neutral, water is added to emulsify, then an amine chain extender is added and the reaction continues, the organic solvent is removed to obtain the waterborne polyurethane emulsion.

[0018] Preferably, diisocyanate, polyether polyol, hydrophilic chain extender, cyclodextrin, and catalyst are mixed and reacted at 80-90℃ for 1-2 hours.

[0019] Preferably, modified silica is added, and the reaction is continued at 80-90℃ for 0.5-1h.

[0020] Preferably, a small molecule chain extender is added, and the reaction is continued at 80-90℃ for 0.5-1h.

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

[0022] The present invention also proposes the application of the above-mentioned waterborne polyurethane emulsion in microfiber leather.

[0023] The present invention also proposes a polyamide microfiber leather, comprising: a polyamide island fiber base fabric and an aqueous polyurethane emulsion as described in any one of claims 1-4.

[0024] The present invention also proposes a method for preparing the above-mentioned polyamide microfiber leather, comprising the following steps: soaking a polyamide island fiber base fabric in a formic acid aqueous solution to obtain a pretreated base fabric; impregnating the pretreated base fabric with an aqueous polyurethane emulsion, drying, performing a weight reduction treatment with alkaline water, washing with water, and drying to obtain polyamide microfiber leather.

[0025] Preferably, the formic acid aqueous solution has a mass fraction of 0.8-1 wt%.

[0026] Preferably, the solution is soaked in an aqueous formic acid solution at room temperature for 7-8 hours.

[0027] Preferably, the alkaline solution is an aqueous solution of sodium hydroxide with a mass fraction of 8-12 wt%.

[0028] Preferably, the weight reduction treatment is carried out at 80-90℃ for 20-30 minutes.

[0029] This invention first soaks the polyamide island fiber base fabric in formic acid, making the base fabric looser and exposing a large number of amino groups on the surface, thus improving its hydrophilicity and promoting the expulsion of water vapor and gas. Then, the micropores formed by cyclodextrin and modified silica significantly improve the air permeability of the invention. Furthermore, the amino groups on the surface of the base fabric can covalently bind with the active groups in the polyurethane emulsion, fixing the polyurethane. On the one hand, this can prevent the polyurethane from migrating with water during drying and forming hollow cores. On the other hand, the synergistic effect of cyclodextrin and triethylenetetramine can increase the network density of the polyurethane, improve the mechanical properties of the polyurethane, prevent polyurethane loss, and prevent the loosening of the base fabric from reducing mechanical properties. The synergistic effect of these multiple functions gives the microfiber leather a good hand feel.

[0030] Beneficial effects:

[0031] This invention prepares modified silica with a specific structure and combines it with appropriate amounts of cyclodextrin and triethylenetetramine to achieve uniform distribution of micropores in polyurethane and increase the network density of polyurethane, thereby improving the mechanical properties and breathability of polyurethane. Furthermore, the specific structure of the modified silica enhances the water resistance of microfiber leather. Additionally, pretreatment of the polyamide island fiber base fabric makes the fabric more loose and contains a large amount of amino groups, further improving the breathability of microfiber leather and allowing the base fabric to covalently bond with polyurethane, preventing hollow cores and leakage problems in microfiber leather and improving its hand feel. Detailed Implementation

[0032] The technical solution of the present invention will now be described in detail through specific embodiments.

[0033] Example 1

[0034] A waterborne polyurethane emulsion, comprising the following raw materials by weight: 20 parts isophorone diisocyanate, 50 parts polytetrahydrofuran 2000, 3 parts cyclodextrin, 1.8 parts dimethylolpropionic acid, 3 parts modified silica, 0.4 parts 1,4-butanediol, 1.2 parts triethylenetetramine, 0.01 parts organobismuth catalyst, and 160 parts water;

[0035] In the preparation of modified silica, γ-glycidoxypropyltrimethoxysilane modified silica particles 1 with a particle size of 2-3 μm and γ-aminopropyltriethoxysilane modified silica particles 2 with a particle size of 50-100 nm, ethanol, ammonia, and water are uniformly dispersed and reacted at 70℃ for 7 h. After filtration, the filter cake is washed and dried to obtain modified silica. The weight ratio of silica particles 1, silica particles 2, ethanol, ammonia, and water is 1:3.5:40:2:3.

[0036] The preparation method of the above-mentioned waterborne polyurethane emulsion includes the following steps: In a nitrogen atmosphere, isophorone diisocyanate, polytetrahydrofuran 2000, dimethylolpropionic acid, cyclodextrin, and organic bismuth catalyst are mixed and reacted at 80°C for 2 hours. Then, modified silica is added and the reaction continues at 80°C for 1 hour. Then, 1,4-butanediol is added and the reaction continues at 80°C for 1 hour. Acetone is added to reduce viscosity, and the pH is adjusted to neutral with triethylamine. Water is added for emulsification, and then triethylenetetramine is added and the reaction continues at room temperature for 1 hour. The acetone is removed to obtain the waterborne polyurethane emulsion.

[0037] A method for preparing polyamide microfiber leather includes the following steps: Soaking a polyamide island fiber base fabric in a 0.8 wt% formic acid aqueous solution at room temperature for 8 hours, then removing and washing with water to obtain a pretreated base fabric; taking the above-mentioned aqueous polyurethane emulsion, adjusting the viscosity to 3000 mPa·s, then impregnating the pretreated base fabric, then drying at 120℃ for 30 min, then using an 8 wt% sodium hydroxide aqueous solution for weight reduction treatment at 90℃ for 20 min, washing with water, and drying to obtain polyamide microfiber leather.

[0038] Example 2

[0039] A waterborne polyurethane emulsion, the raw materials of which, by weight, include: 20 parts isophorone diisocyanate, 55 parts polytetrahydrofuran 2000, 2 parts cyclodextrin, 2.0 parts dimethylolpropionic acid, 2 parts modified silica, 0.6 parts 1,4-butanediol, 1 part triethylenetetramine, 0.012 parts organobismuth catalyst, and 140 parts water;

[0040] In the preparation of modified silica, γ-glycidoxypropyltrimethoxysilane modified silica particles 1 with a particle size of 2-3 μm and γ-aminopropyltriethoxysilane modified silica particles 2 with a particle size of 50-100 nm, ethanol, ammonia, and water are uniformly dispersed and reacted at 75℃ for 6 h. After filtration, the filter cake is washed and dried to obtain modified silica. The weight ratio of silica particles 1, silica particles 2, ethanol, ammonia, and water is 1:4:30:2.5:2.5.

[0041] The preparation method of the above-mentioned waterborne polyurethane emulsion includes the following steps: In a nitrogen atmosphere, isophorone diisocyanate, polytetrahydrofuran 2000, dimethylolpropionic acid, cyclodextrin, and organic bismuth catalyst are mixed and reacted at 90°C for 1 h. Then, modified silica is added and the reaction is continued at 90°C for 0.5 h. Then, 1,4-butanediol is added and the reaction is continued at 90°C for 0.5 h. Acetone is added to reduce viscosity, and the pH is adjusted to neutral with triethylamine. Water is added for emulsification, and then triethylenetetramine is added and the reaction is continued at room temperature for 0.5 h. The acetone is removed to obtain the waterborne polyurethane emulsion.

[0042] A method for preparing polyamide microfiber leather includes the following steps: immersing a polyamide island fiber base fabric in a 1 wt% formic acid aqueous solution at room temperature for 7 hours, then removing and washing with water to obtain a pretreated base fabric; taking the above-mentioned aqueous polyurethane emulsion, adjusting the viscosity to 3000 mPa·s, then impregnating the pretreated base fabric, then drying at 120°C for 30 minutes, then treating with a 12 wt% sodium hydroxide aqueous solution at 80°C for 30 minutes, washing with water, and drying to obtain polyamide microfiber leather.

[0043] Example 3

[0044] A waterborne polyurethane emulsion, comprising the following raw materials by weight: 20 parts isophorone diisocyanate, 53 parts polytetrahydrofuran 2000, 2.5 parts cyclodextrin, 1.9 parts dimethylolpropionic acid, 2.5 parts modified silica, 0.5 parts 1,4-butanediol, 1.1 parts triethylenetetramine, 0.01 parts organobismuth catalyst, and 150 parts water;

[0045] In the preparation of modified silica, γ-glycidoxypropyltrimethoxysilane modified silica particles 1 with a particle size of 2-3 μm and γ-aminopropyltriethoxysilane modified silica particles 2 with a particle size of 50-100 nm, ethanol, ammonia, and water are uniformly dispersed and reacted at 75℃ for 6 h. After filtration, the filter cake is washed and dried to obtain modified silica. The weight ratio of silica particles 1, silica particles 2, ethanol, ammonia, and water is 1:3.8:35:2:2.5.

[0046] The preparation method of the above-mentioned waterborne polyurethane emulsion includes the following steps: In a nitrogen atmosphere, isophorone diisocyanate, polytetrahydrofuran 2000, dimethylolpropionic acid, cyclodextrin, and organic bismuth catalyst are mixed and reacted at 85°C for 1.5 h. Then, modified silica is added and the reaction continues at 85°C for 0.8 h. Then, 1,4-butanediol is added and the reaction continues at 85°C for 0.8 h. Acetone is added to reduce viscosity, and the pH is adjusted to neutral with triethylamine. Water is added for emulsification, and then triethylenetetramine is added and the reaction continues at room temperature for 0.8 h. The acetone is removed to obtain the waterborne polyurethane emulsion.

[0047] A method for preparing polyamide microfiber leather includes the following steps: immersing a polyamide island fiber base fabric in a 1 wt% formic acid aqueous solution at room temperature for 7.5 h, then removing and washing with water to obtain a pretreated base fabric; taking the above-mentioned aqueous polyurethane emulsion, adjusting the viscosity to 3000 mPa·s, then impregnating the pretreated base fabric, then drying at 120°C for 30 min, then treating with a 10 wt% sodium hydroxide aqueous solution at 85°C for 30 min, washing with water, and drying to obtain polyamide microfiber leather.

[0048] Comparative Example 1

[0049] It does not contain modified silica, and is otherwise the same as in Example 3.

[0050] Comparative Example 2

[0051] It does not contain cyclodextrin, and is otherwise the same as in Example 3.

[0052] Comparative Example 3

[0053] The polyamide island fiber base fabric was impregnated directly with water-based polyurethane emulsion without pretreatment, and other procedures were the same as in Example 3.

[0054] Comparative Example 4

[0055] The modified silica was 4 parts, and the rest was the same as in Example 3.

[0056] Comparative Example 5

[0057] The modified silica was 1 part, and the rest was the same as in Example 3.

[0058] The properties of the microfiber leather prepared in each group were tested, and the results are shown in Table 1.

[0059] Tested according to GB / T 12704.2-2009 "Textiles - Test methods for moisture permeability of fabrics - Part 2: Evaporation method".

[0060] Table 1 Test Results

[0061]

[0062]

[0063] As can be seen from Table 1, the polyamide microfiber leather described in this invention has no hollow core, good breathability, and good waterproof properties.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A waterborne polyurethane emulsion, characterized in that, The raw materials, by weight, include: 20 parts diisocyanate, 50-55 parts polyether polyol, 2-3 parts cyclodextrin, 1.8-2.0 parts hydrophilic chain extender, 2-3 parts modified silica, 0.4-0.6 parts small molecule chain extender, 1-1.2 parts amine chain extender, 0.01-0.012 parts catalyst, and 140-160 parts water; In the preparation of modified silica, silica particles 1 with a particle size of 2-3 μm and silica particles 2 with a particle size of 50-100 nm, ethanol, ammonia, and water are uniformly dispersed and reacted to obtain modified silica. Silica particles 1 have epoxy groups grafted onto their surface, and silica particles 2 have amino groups grafted onto their surface.

2. The aqueous polyurethane emulsion according to claim 1, characterized in that, In the preparation of modified silica, the weight ratio of silica particles 1 to silica particles 2 is 1:3.5-4.

3. The aqueous polyurethane emulsion according to claim 1, characterized in that, In the preparation of modified silica, the weight ratio of silica particles 1 to ethanol, ammonia, and water is 1:30-40:2-2.5:2.5-3.

4. The aqueous polyurethane emulsion according to claim 1, characterized in that, In the preparation of modified silica, the reaction is carried out at 70-75℃ for 6-7 hours.

5. The aqueous polyurethane emulsion according to claim 1, characterized in that, The diisocyanate is isophorone diisocyanate.

6. The aqueous polyurethane emulsion according to claim 1, characterized in that, The polyether polyol is polytetrahydrofuran.

7. The aqueous polyurethane emulsion according to claim 1, characterized in that, The hydrophilic chain extender is dimethylolpropionic acid.

8. The aqueous polyurethane emulsion according to claim 1, characterized in that, The small molecule chain extender is 1,4-butanediol.

9. The aqueous polyurethane emulsion according to claim 1, characterized in that, The amine chain extender is triethylenetetramine.

10. A method for preparing an aqueous polyurethane emulsion as described in any one of claims 1-9, characterized in that, The process includes the following steps: In an inert gas atmosphere, diisocyanate, polyether polyol, hydrophilic chain extender, cyclodextrin, and catalyst are mixed and reacted. Then, modified silica is added to continue the reaction, followed by the addition of a small molecule chain extender. Organic solvent is added to reduce viscosity, and the pH is adjusted to neutral. Water is added for emulsification, followed by the addition of an amine chain extender. The reaction continues until the organic solvent is removed, yielding an aqueous polyurethane emulsion.

11. The method for preparing the aqueous polyurethane emulsion according to claim 10, characterized in that, Mix diisocyanate, polyether polyol, hydrophilic chain extender, cyclodextrin, and catalyst, and react at 80-90℃ for 1-2 hours.

12. The method for preparing the aqueous polyurethane emulsion according to claim 10, characterized in that, Add modified silica and continue the reaction at 80-90℃ for 0.5-1h.

13. The method for preparing the aqueous polyurethane emulsion according to claim 10, characterized in that, Add a small molecule chain extender and continue the reaction at 80-90℃ for 0.5-1h.

14. The method for preparing the aqueous polyurethane emulsion according to claim 10, characterized in that, Add an amine chain extender and continue the reaction at room temperature for 0.5-1 h.

15. The application of the waterborne polyurethane emulsion as described in any one of claims 1-9 in microfiber leather.

16. A polyamide microfiber leather, characterized in that, include: Polyamide island fiber base fabric and the waterborne polyurethane emulsion as described in any one of claims 1-9; The polyamide island fiber base fabric is pretreated, and the pretreatment steps include: immersing the polyamide island fiber base fabric in a formic acid aqueous solution.

17. A method for preparing polyamide microfiber leather as described in claim 16, characterized in that, The process includes the following steps: soaking a polyamide island fiber base fabric in a formic acid aqueous solution to obtain a pretreated base fabric; impregnating the pretreated base fabric with an aqueous polyurethane emulsion, drying it, performing a weight reduction treatment with alkaline water, washing it with water, and drying it to obtain polyamide microfiber leather.

18. The method for preparing polyamide microfiber leather according to claim 17, characterized in that, The mass fraction of formic acid in aqueous solution is 0.8-1 wt%.

19. The method for preparing polyamide microfiber leather according to claim 17, characterized in that, Soak in formic acid aqueous solution at room temperature for 7-8 hours.

20. The method for preparing polyamide microfiber leather according to claim 17, characterized in that, The alkaline solution is an aqueous solution of sodium hydroxide with a mass fraction of 8-12 wt%.

21. The method for preparing polyamide microfiber leather according to claim 17, characterized in that, Reduce the volume at 80-90℃ for 20-30 minutes.

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