Environment-friendly multifunctional artificial leather material and preparation method thereof

Abstract

The invention relates to the field of polymer composite materials, and discloses an environment-friendly multifunctional artificial leather material and a preparation method thereof. The preparation method comprises the following steps: mixing waterborne polyurethane, a micro foaming agent, a dispersing agent, a cross-linking agent and modified ZnO coated SiO2 to prepare a main body mixture, coating a polyester knitted fabric with the main body mixture, and carrying out static settlement and thermal foaming treatment to obtain a finished product. A modified ZnO-coated SiO2 mixed system is prepared through a specific process, and ZnO nanoparticles are prepared firstly and then subjected to composite modification. Compared with a traditional material, the waterborne polyurethane is adopted, release of volatile matter such as VOC is remarkably reduced, and more environment friendliness is achieved; the unique formula and process endow the material with the properties of high temperature resistance, ultraviolet resistance, water resistance, air permeability and the like. The ZnO nanoparticles are dispersed and modified, and a compact protective layer is formed on the outer layer of the coating by a modifier through standing and precipitation, so that the comprehensive performance of the material is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer composite materials, and particularly relates to an environment-friendly multifunctional artificial leather material and a preparation method thereof. Background Art

[0002] As a substitute for natural leather, artificial leather is widely used in multiple industries due to its high production efficiency, low cost, controllable appearance, etc. However, with the continuous improvement of global environmental protection standards, the use of organic solvents and VOC release problems in the production process of traditional artificial leather have attracted increasing attention. Traditional artificial leather materials mainly use polyurethane resin containing organic solvents as the base material, and a large amount of volatile organic compounds (VOCs) will be released during processing and use, posing a potential threat to human health and the environment.

[0003] In addition, ordinary artificial leather materials generally have the problem of poor heat resistance. During use, they are easily thermally aged, become hard or brittle, and lose flexibility, making them unsuitable for high-temperature environments, severely limiting their usage scenarios. At the same time, due to the insufficient breathability of traditional artificial leather, the use comfort is relatively low, and it is not suitable for high-end furniture and automotive interior fields with high requirements for touch and breathability, such as seat covering, wall soft decoration, etc., which also restricts its promotion in high-end occasions.

[0004] Therefore, in the era of surging demand for leather, developing an artificial leather material with low VOCs release, high temperature resistance, ultraviolet resistance, waterproofness, and good breathability has become an urgent need in the industry. Summary of the Invention

[0005] Based on the deficiencies of the above-mentioned existing technologies, the present invention provides an environment-friendly multifunctional artificial leather material and a preparation method thereof. This method uses waterborne polyurethane to prepare artificial leather materials, effectively reducing the release of volatiles such as VOCs on the basis of the original artificial leather, and greatly increasing its environmental friendliness. In addition, through the formulation research of the mixed system of waterborne polyurethane, micro-foaming agent, dispersant, cross-linking agent, and modified ZnO@SiO2, it has properties such as high temperature resistance, ultraviolet resistance, waterproofness, and good breathability.

[0006] To achieve the above object, the present invention provides the following technical solutions: A preparation method of an environment-friendly multifunctional artificial leather material is provided, and the method includes the following steps: S11. Prepare the main mixture: Weigh the corresponding mass parts of waterborne polyurethane, micro-foaming agent, dispersant, cross-linking agent, and modified ZnO@SiO2 mixed system, and place them in a high-speed mixer to mix evenly to form the main mixture; S12. Preparation of the foamed composite layer: Weigh the polyester knitted fabric with the corresponding mass percentage, and use a coater to coat the main mixture described in step S11 on the surface of the polyester knitted fabric. The coating thickness is 1 mm, the coating speed is 20 mm / min, and the temperature is 25 °C to form a foamed composite layer; S13. Static precipitation: Place the coating layer of the foamed composite layer prepared in step S12 face down and let it stand for 10 min; S14. Thermal foaming treatment: Put the foamed composite layer in step S13 into a hot air drying tunnel at a temperature of 100 °C for 30 min to form a porous soft intermediate layer and cure the surface layer structure to obtain an environmentally friendly artificial leather product.

[0007] As a further preference for the preparation method of an environmentally friendly and multifunctional artificial leather material.

[0008] Preferably, the dosages of the aqueous polyurethane, micro-foaming agent, dispersant, cross-linking agent, modified ZnO@SiO2 mixed system, and polyester knitted fabric are respectively: 80 parts by mass, 2 parts by mass, 50 parts by mass, 0.5 parts by mass, 10 - 15 parts by mass, and 100 parts by mass; Preferably, the solid content of the aqueous polyurethane is: 35%; Preferably, the micro-foaming agent is: sodium bicarbonate with a purity of 99.9%; Preferably, the dispersant is: deionized water; Preferably, the cross-linking agent is: isophorone diisocyanate with a purity of 99.9%.

[0009] Preferably, the preparation method of the modified ZnO@SiO2 mixed system includes the following steps: S21. Preparation of the modified ZnO@SiO2 mixed system: Weigh tetraethyl orthosilicate, absolute ethanol, deionized water I, and nitric acid, react them under a water bath condition at 60 °C for 3 h, then let it stand at room temperature for 24 h, then add deionized water II, heat it to 85 °C, evaporate the absolute ethanol and nitric acid, then add sodium dodecyl sulfate, then disperse ZnO nanoparticles with an average particle size of 4.5 nm into the SiO2 aqueous solution through a high-speed disperser, then add hexamethyldiazane and stir it through a disperser for 15 min, and then let it stand and age for 1 day to obtain the modified ZnO@SiO2 mixed system.

[0010] Preferably, the addition amounts of tetraethyl orthosilicate, absolute ethanol, deionized water I, nitric acid, deionized water II, sodium dodecyl sulfate, ZnO nanoparticles, and hexamethyldiazane in step S21 are respectively: 15 parts by mass, 40 parts by mass, 1 part by mass, 0.5 part by mass, 100 parts by mass, 0.1 part by mass, 1 part by mass, and 0.2 part by mass.

[0011] Preferably, the stirring speed of the high-speed disperser described in step S22 is 2000 rmp / min.

[0012] An environment-friendly and multifunctional artificial leather material is prepared according to the above preparation method.

[0013] The beneficial effects of the present invention compared with the prior art are as follows: (1) The present invention uses waterborne polyurethane to prepare artificial leather materials, effectively reducing the release of volatile substances such as VOC on the basis of the original artificial leather, and greatly increasing its environmental protection. In addition, through the research on the formulation and process of the mixed system of waterborne polyurethane, micro-foaming agent, dispersant, cross-linking agent and modified ZnO@SiO2, it has properties such as high temperature resistance, ultraviolet resistance, waterproofness and good air permeability.

[0014] (2) In the present invention, ZnO nanoparticles with an average particle size of 4.5 nm are added to the system. These particles absorb ultraviolet light and can be converted into visible light, thus avoiding heat rise. However, particles of this particle size are extremely easy to agglomerate. In the present invention, by adding a surfactant to the system and through high-speed dispersion, the ZnO nanoparticles are dispersed in the SiO2 system, and a modified ZnO@SiO2 mixed system is obtained through modification.

[0015] (3) In the present invention, the modified ZnO@SiO2 is precipitated on the outer layer of the coating by static precipitation, and then heated and cured to form a relatively dense protective layer on the outermost layer, so as to have better high temperature resistance, ultraviolet resistance and waterproof performance. Description of the Drawings

[0016] Figure 1 is the cross-sectional SEM picture of the environment-friendly and multifunctional artificial leather material prepared in Example 1; Figure 2 is the TEM photo of the modified ZnO@SiO2 mixed system prepared in Example 1; Figure 3 is the VOC release amount graph of Examples 1-3 and Comparative Example 2 for 72 h; Figure 4 is the absorption rate spectrum of Examples 1-3, Comparative Example 1 and Comparative Example 4; Figure 5 is the fluorescence emission spectrum of Examples 1-3 and Comparative Example 1; Figure 6 is the elongation rate of Examples 1-3 and Comparative Example 1 after heat treatment at 150 °C; Figure 7 is the air permeability value of Examples 1-3 and Comparative Example 3; Figure 8 is the water contact angle of Examples 1-3, Comparative Example 1 and Comparative Example 4. Detailed Embodiments

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the following describes the specific implementation manners of the present invention in detail with reference to embodiments. The following content is only an example and illustration of the concept of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific implementation cases or use similar methods to replace them. As long as they do not deviate from the concept of the invention or exceed the scope defined by this claim book, they should all fall within the protection scope of the present invention.

[0018] The above preparation method of the present invention will be described below through specific examples and comparative examples. Example 1

[0019] This example provides an environmentally friendly multifunctional artificial leather material and its preparation method. The preparation steps are as follows: S11. Prepare the main mixture: Weigh 80 parts by mass of waterborne polyurethane, 2 parts by mass of micro-foaming agent, 50 parts by mass of dispersant, 0.5 part by mass of crosslinking agent and 10 parts by mass of modified ZnO@SiO2 mixed system, and place them in a high-speed mixer to mix evenly to form the main mixture; S12. Prepare the foaming composite layer: Weigh 100 parts by mass of polyester knitted fabric, and use a coater to coat the main mixture described in step S11 on the surface of the polyester knitted fabric. The coating thickness is 1 mm, the coating speed is 20 mm / min, and the temperature is 25 °C to form a foaming composite layer; S13. Static precipitation: Place the coating layer of the foaming composite layer prepared in step S12 downward and let it stand for 10 min; S14. Thermal foaming treatment: Put the foaming composite layer in step S13 into a hot air drying tunnel at a temperature of 100 °C for 30 min to form a porous soft intermediate layer and cure the surface layer structure to obtain an environmentally friendly artificial leather product.

[0020] In addition, the solid content of the waterborne polyurethane is: 35%; The micro-foaming agent is: sodium bicarbonate, with a purity of 99.9%; The dispersant is: deionized water; The crosslinking agent is: isophorone diisocyanate, with a purity of 99.9%.

[0021] An environmentally friendly multifunctional artificial leather material is obtained through the above preparation method.

[0022] Among them, the preparation method of the modified ZnO@SiO2 mixed system has the following preparation steps: S21. Preparation of modified ZnO@SiO2 hybrid system: Weigh 15 parts by mass of tetraethyl orthosilicate, 40 parts by mass of absolute ethanol, 1 part by mass of deionized water I, and 0.5 part by mass of nitric acid. React them under a water bath condition at 60 °C for 3 h, then let it stand at room temperature for 24 h. Then add 100 parts by mass of deionized water II, heat it to 85 °C, evaporate off the absolute ethanol and nitric acid. Then add 0.1 part by mass of sodium dodecyl sulfate. Then disperse 1 part by mass of ZnO nanoparticles with an average particle size of 4.5 nm into the SiO2 aqueous solution by a high-speed disperser at 2000 rmp / min. Then add 0.2 part by mass of hexamethyldiazane and stir it with the disperser for 15 min. Then let it stand and age for 1 day to obtain the modified ZnO@SiO2 hybrid system. Example 2

[0023] The difference between this example and Example 1 is that the dosage of the modified ZnO@SiO2 hybrid system in step S11 is 12 parts by mass. Example 3

[0024] The difference between this example and Example 1 is that the dosage of the modified ZnO@SiO2 hybrid system in step S11 is 15 parts by mass. Comparative Example 1

[0025] The difference between this comparative example and Example 1 is that the modified ZnO@SiO2 hybrid system is not added. Comparative Example 2

[0026] The difference between this comparative example and Example 1 is that the main material added is solvent-based polyurethane. Comparative Example 3

[0027] The difference between this comparative example and Example 1 is that no micro-foaming agent is added in the treatment of step S11. Comparative Example 4

[0028] The difference between this comparative example and Example 1 is that the treatment of step S13 is not carried out.

[0029] Figure 1 It is the cross-sectional SEM image of the environmentally friendly multi-functional artificial leather material prepared in Example 1; it can be seen that there are a large number of pores inside the material, and the interface is significantly denser than the inside. This shows that this structure not only has good air permeability, but the dense structure at the interface can also improve the high-temperature resistance, ultraviolet resistance and waterproof performance of the material.

[0030] Figure 2is the TEM photograph of the modified ZnO@SiO2 hybrid system prepared in Example 1; it can be seen that a modified ZnO@SiO2 hybrid system with better dispersibility can be prepared by the method in the present invention. In the present invention, some other experimental methods have also been tried, such as directly adding ZnO, and the acid in the SiO2 system will react with ZnO. Without adding the surfactant sodium dodecyl sulfate, precipitation will occur after adding ZnO nanoparticles.

[0031] Figure 3 is the VOC release amount diagram of Examples 1-3 and Comparative Example 2 at 72 h; it can be seen that the VOC release amounts of all examples are less than those of the comparative examples. Therefore, it is considered that the VOC release amount of this formulation is lower than that of traditional artificial leather and has better environmental protection.

[0032] Figure 4 is the absorption rate spectrum of Examples 1-3, Comparative Example 1 and Comparative Example 4; it can be seen that the materials of Examples 1-3 have stronger ultraviolet absorption ability and better anti-ultraviolet aging ability, which is caused by the ZnO material absorbing ultraviolet light.

[0033] Figure 5 is the fluorescence emission spectrum of Examples 1-3 and Comparative Example 1; as shown by the fluorescence spectrum, ZnO nanoparticles can not only absorb ultraviolet light, but also convert ultraviolet light into visible light, thereby reducing the absorption of ultraviolet light by ZnO and converting it into heat, and increasing the service life of the material.

[0034] Figure 6 is the elongation at break of Examples 1-3, Comparative Example 1 and Comparative Example 4 after heat treatment at 150 °C; it can be seen that the high-temperature resistance of Examples 1-3 is better than that of the comparative examples.

[0035] Figure 7 is the air permeability value of Examples 1-3 and Comparative Example 3; it can be seen that the air permeability of Examples 1-3 is better than that of Comparative Example 3.

[0036] Figure 8 is the water contact angle of Examples 1-3, Comparative Example 1 and Comparative Example 4. The water contact angle shows that Examples 1-3 have a higher water contact angle, which indicates that water droplets are more likely to roll off the material surface, thereby improving the waterproof performance of the artificial leather material. In addition, Comparative Example 4 shows that without operating in step S13 of the example, less deposition of the modified ZnO@SiO2 hybrid system occurs at the interface, resulting in a smaller water contact angle.

[0037] In addition, from Figure 4 、 Figure 6 and Figure 8, it can be concluded that in the present invention, modified ZnO@SiO2 is precipitated on the outer layer of the coating through static precipitation, and then cured by heating to form a relatively dense protective layer on the outermost layer, thus having better high-temperature resistance, ultraviolet resistance and waterproof performance.

[0038] In summary, the environmentally friendly and multifunctional artificial leather material prepared by the present invention has a low VOC volatilization amount, less volatile components, and higher environmental friendliness. In addition, the environmentally friendly and multifunctional artificial leather material has excellent high-temperature resistance, ultraviolet resistance, waterproofness, air permeability and other properties, and can have good environmental friendliness while ensuring the use performance, and is suitable for the high-end leather field.

Claims

1. A preparation method of an environment-friendly and multifunctional artificial leather material, characterized in that, The method includes the following steps: S11. Prepare the main mixture: Weigh the corresponding mass parts of waterborne polyurethane, micro-foaming agent, dispersant, cross-linking agent and modified ZnO@SiO2 mixed system, place them in a high-speed mixer and mix evenly to form the main mixture. S12. Prepare the foamed composite layer: Weigh the corresponding mass percentage of polyester knitted fabric, and use a coater to coat the main mixture described in step S11 on the surface of the polyester knitted fabric. The coating thickness is 1 mm, the coating speed is 20 mm / min, and the temperature is 25 °C to form the foamed composite layer. S13. Stand and precipitate: Place the coating layer of the foamed composite layer prepared in step S12 downward and stand for 10 min. S14. Thermal foaming treatment: Put the foamed composite layer in step S13 into a hot air drying tunnel at a temperature of 100 °C for 30 min to form a porous and soft intermediate layer and cure the surface layer structure to obtain the finished product of environmentally friendly artificial leather.

2. The preparation method of the environment-friendly multifunctional artificial leather material according to claim 1, characterized in that The dosages of waterborne polyurethane, micro-foaming agent, dispersant, cross-linking agent, modified ZnO@SiO2 mixed system and polyester knitted fabric are respectively: 80 mass parts, 2 mass parts, 50 mass parts, 0.5 mass parts, 10 - 15 mass parts, and 100 mass parts. The solid content of the waterborne polyurethane is: 35%. The micro-foaming agent is: sodium bicarbonate, with a purity of 99.9%. The dispersant is: deionized water. The cross-linking agent is: isophorone diisocyanate, with a purity of 99.9%.

3. The preparation method of the environment-friendly multifunctional artificial leather material according to claim 2, characterized in that, The preparation method of the modified ZnO@SiO2 mixed system includes the following steps: S21. Prepare the modified ZnO@SiO2 mixed system: Weigh tetraethyl orthosilicate, absolute ethanol, deionized water I and nitric acid, react at 60 °C in a water bath for 3 h, then stand at room temperature for 24 h, then add deionized water II, heat to 85 °C, evaporate off the absolute ethanol and nitric acid, then add sodium dodecyl sulfate, then disperse ZnO nanoparticles with an average particle size of 4.5 nm into the SiO2 aqueous solution through a high-speed disperser, then add hexamethyldiazane and stir through the disperser for 15 min, and then stand and age for 1 day to obtain the modified ZnO@SiO2 mixed system.

4. The preparation method of the environment-friendly multifunctional artificial leather material according to claim 3, characterized in that, The addition amounts of tetraethyl orthosilicate, absolute ethanol, deionized water I, nitric acid, deionized water II, sodium dodecyl sulfate, ZnO nanoparticles and hexamethyldiazane in step S21 are respectively: 15 mass parts, 40 mass parts, 1 mass part, 0.5 mass part, 100 mass parts, 0.1 mass part, 1 mass part and 0.2 mass part.

5. The preparation method of the environment-friendly multi-functional artificial leather material according to claim 3, characterized in that, The stirring speed of the high-speed disperser described in step S21 is 2000 rmp / min.

6. An environmentally friendly and multifunctional artificial leather material prepared by the preparation method according to any one of claims 1 - 5.

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