Yangbuck leather easy to clean and preparation method thereof

Abstract

The invention discloses easy-to-clean Yangbuck leather and a preparation method thereof, and belongs to the technical field of artificial leather. Through the synergistic effect of the lignin nanoparticles, the polydimethylsiloxane and the palm wax, a stable micro-nano composite hydrophobic structure is successfully constructed on the surface of the Yangbuck leather. The water contact angle of the treated leather surface is larger than 155 degrees, the rolling angle is smaller than 5 degrees, common pollutants cannot be attached to the treated leather surface, the treated leather surface can completely roll down only by inclining or slightly flushing the treated leather surface with water, the self-cleaning effect is achieved, and the anti-pollution capacity and daily maintenance convenience of a product are greatly improved; after 5000 times of Martindale wear resistance and more than 10000 times of scrubbing resistance tests, the super-hydrophobic coating can still keep good super-hydrophobic performance, the defects that a traditional coating is prone to being abraded and falling off are overcome, and the service life is remarkably prolonged; lignin selected by the invention is a renewable biomass resource, PDMS and palm wax are non-toxic and harmless environment-friendly materials, and the whole process is free of fluorination and conforms to the green chemistry concept.

Description

Technical Field

[0001] This invention belongs to the field of artificial leather technology, specifically relating to an easy-to-clean sheepskin leather and its preparation method. Background Technology

[0002] Artificial leather, as an important textile composite material, is widely used in furniture, bags, footwear, and automotive interiors. Among them, sheepskin leather is particularly favored for its unique micro-suede texture, soft and delicate feel, and luxurious and elegant appearance. However, this special surface structure is also a double-edged sword. Its high porosity and large specific surface area make it extremely prone to adsorbing dust, oil stains, liquids, and other contaminants. Once stains penetrate into the micropores, they are difficult to remove completely, seriously affecting the product's appearance and lifespan. Traditional cleaning methods are often ineffective and may even damage the suede surface.

[0003] Currently, the mainstream technology for imparting stain resistance to materials is the creation of superhydrophobic surfaces. Traditional superhydrophobic finishing typically relies on fluorinated compounds (such as PFOA and PFOS) or inorganic nanoparticles (such as silica). While fluorinated compounds offer extremely low surface energy, they are classified as persistent organic pollutants due to their difficulty in degradation and their toxicity accumulated in organisms, and are subject to increasingly stringent environmental regulations. Inorganic nanoparticles, on the other hand, suffer from weak adhesion to the substrate, a rough feel, potential clogging of leather micropores affecting breathability, and are not environmentally friendly in their production.

[0004] Therefore, developing a new finishing technology that can give sheepskin efficient and durable easy-cleaning properties, maintain its original velvet feel and breathability, and meet green and environmental protection requirements has become a key issue that urgently needs to be addressed in this field. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide an easy-to-clean sheepskin and its preparation method. The water contact angle of the leather surface of this invention is greater than 155° and the rolling angle is less than 5°. Common pollutants cannot adhere to it and can be completely rolled off simply by tilting or rinsing with water, achieving a "self-cleaning" effect and greatly improving the product's stain resistance and the convenience of daily maintenance.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing easy-to-clean sheepskin leather, comprising the following steps:

[0008] The semi-finished sheepskin is subjected to low-temperature plasma treatment, then electrostatic spraying of functional additives, and finally pre-drying and UV curing to obtain easy-to-clean sheepskin.

[0009] Low-temperature plasma treatment can clean the surface and introduce more active groups on the velvet fibers, greatly improving the adhesion of subsequent finishing agents.

[0010] Preferably, the preparation method of the semi-finished sheepskin leather is as follows: the raw material solution is poured into a PVC coating machine, and the PVC surface layer, PVC foam layer, and PVC adhesive layer are coated sequentially, and then the lining layer is attached to obtain the semi-finished product. This invention requires further surface treatment of the semi-finished sheepskin leather; therefore, a dry-process preparation method is suitable for producing semi-finished sheepskin leather, which can be either homemade or commercially available.

[0011] Preferably, the electrostatic spraying parameters are: voltage 30-50kV, spray gun diameter 0.3-0.5mm, flow rate 0.5mL / min, and distance 15-20cm. Electrostatic spraying enables the charged finishing liquid droplets to more evenly and comprehensively coat each velvet fiber, achieving three-dimensional coverage.

[0012] Preferably, the preparation method of the functional additive is as follows:

[0013] S1. Completely dissolve sodium lignin sulfonate in tetrahydrofuran and stir until clear and transparent to obtain a lignin solution; then, under high-speed shear, add the lignin solution dropwise to deionized water to obtain a crude solution;

[0014] S2. Transfer the crude liquid to a dialysis bag and dialyze it in flowing deionized water for 48 hours to completely remove THF and impurities. Then concentrate the liquid to obtain a lignin nanoparticle dispersion with a solid content of 2.5%.

[0015] S3. In a light-proof container, dissolve polydimethylsiloxane, palm wax and silane coupling agent in ethyl acetate and stir until homogeneous. Then slowly add lignin nanoparticle dispersion and continue stirring. Finally, add photoinitiator and stir until completely dissolved to obtain functional additive.

[0016] Lignin itself contains aromatic rings and alkyl groups, and has a certain degree of hydrophobicity. When it is nano-sized, it provides the micro-nano secondary rough structure required to build superhydrophobic surfaces, which is more environmentally friendly and lower in cost.

[0017] Preferably, the mass ratio of sodium lignosulfonate, tetrahydrofuran, and deionized water in S1 is (1-5):(95-99):200.

[0018] Preferably, the high-speed shear rate in S1 is 8000-10000 rpm.

[0019] Preferably, the molecular weight cutoff in the dialysis bag in S2 is 3500-5000 Da.

[0020] Preferably, the mass ratio of polydimethylsiloxane, palm wax, silane coupling agent, ethyl acetate, lignin nanoparticle dispersion, and photoinitiator in S3 is 3:(0.1-1):0.5:(50-60):(40-50):1.

[0021] PDMS provides extremely low surface energy, which is the main source of hydrophobicity, giving the coating high elasticity, flexibility, and durability. Carnauba wax and PDMS work synergistically to further enhance hydrophobicity and give sheepskin a smoother feel and a certain degree of abrasion resistance. Lignin nanoparticles form nanoscale protrusions in the coating, which, together with PDMS / wax, construct a lotus leaf-like micro-nano composite structure to achieve the superhydrophobic effect.

[0022] Preferably, the pre-drying temperature is 60°C and the drying time is 3 minutes.

[0023] Preferably, the UV curing wavelength is 365nm and the energy density is 600-800mJ / cm². 2 .

[0024] The present invention also provides an easy-to-clean sheepskin, which is prepared by the above-described preparation method.

[0025] It contains at least the following beneficial technical effects:

[0026] This invention successfully constructs a stable micro-nano composite hydrophobic structure on the surface of sheepskin through the synergistic effect of lignin nanoparticles, polydimethylsiloxane, and palm wax. The treated leather surface has a water contact angle greater than 155° and a roll-off angle less than 5°, preventing common contaminants from adhering. These contaminants can be completely rolled off simply by tilting the leather or rinsing it lightly with water, achieving a "self-cleaning" effect and greatly improving the product's stain resistance and ease of daily maintenance.

[0027] Tests have shown that the product maintains excellent superhydrophobic properties after 5,000 Martindale abrasion tests and over 10,000 brush wash tests, overcoming the shortcomings of traditional coatings that are prone to wear and peeling, and significantly extending its service life.

[0028] The lignin used in this invention is a renewable biomass resource, and both PDMS and palm wax are non-toxic and harmless environmentally friendly materials. The entire process is fluorine-free, conforming to the concept of green chemistry. At the same time, the resulting functional coating is ultra-thin and flexible, which, while providing functionality, retains the original softness, velvet feel, and breathability of sheepskin to the maximum extent. This avoids problems such as hardening of the hand and reduced breathability caused by traditional finishing processes, ensuring the comfort of wearing and using the final product. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the sheepskin leather of the present invention.

[0030] In the diagram: 1-anti-fouling layer, 2-epidermal layer, 3-dense layer, 4-adhesive foam layer, 5-fabric layer. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0037] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0038] The semi-finished sheepskin was purchased from Zhejiang Xinbang Industrial Co., Ltd., and consists of layers from top to bottom: the outer skin layer, the dense layer, the adhesive foam layer, and the fabric layer.

[0039] Example 1

[0040] Preparation of functional additives:

[0041] Dissolve 3 parts sodium lignin sulfonate completely in 97 parts tetrahydrofuran and stir until clear and transparent to obtain a lignin solution; then, under high-speed shearing at 9000 rpm, add the lignin solution dropwise to 200 parts deionized water to obtain a crude solution;

[0042] S2. The crude liquid was transferred to a 4000 Da dialysis bag and dialyzed in flowing deionized water for 48 hours to completely remove THF and impurities. Then it was concentrated to obtain a lignin nanoparticle dispersion with a solid content of 2.5%.

[0043] S3. In a light-proof container, dissolve 3 parts of polydimethylsiloxane, 0.5 parts of palm wax and 0.5 parts of silane coupling agent in 55 parts of ethyl acetate and stir until homogeneous. Then slowly add 45 parts of lignin nanoparticle dispersion and continue stirring. Finally, add 1 part of photoinitiator and stir until completely dissolved to obtain the functional additive.

[0044] Surface modification:

[0045] The semi-finished sheepskin was subjected to low-temperature plasma treatment, and then the functional additives were sprayed by electrostatic spraying with the following parameters: voltage 40kV, spray gun diameter 0.4mm, flow rate 0.5mL / min, and distance 18cm.

[0046] Then dry at 60℃ for 3 minutes; finally, at a wavelength of 365nm and an energy density of 700mJ / cm². 2 The leather is UV-cured under light to obtain easy-to-clean sheepskin.

[0047] Example 2

[0048] Preparation of functional additives:

[0049] One part of sodium lignin sulfonate was completely dissolved in 99 parts of tetrahydrofuran and stirred until clear and transparent to obtain a lignin solution; then, under high-speed shearing at 10,000 rpm, the lignin solution was added dropwise to 200 parts of deionized water to obtain a crude solution;

[0050] S2. The crude liquid was transferred to a 5000 Da dialysis bag and dialyzed in flowing deionized water for 48 hours to completely remove THF and impurities. Then it was concentrated to obtain a lignin nanoparticle dispersion with a solid content of 2.5%.

[0051] S3. In a light-proof container, dissolve 3 parts of polydimethylsiloxane, 1 part of palm wax and 0.5 parts of silane coupling agent in 60 parts of ethyl acetate, stir until homogeneous, then slowly add 40 parts of lignin nanoparticle dispersion while stirring continuously, and finally add 1 part of photoinitiator and stir until completely dissolved to obtain the functional additive.

[0052] Surface modification:

[0053] The semi-finished sheepskin was subjected to low-temperature plasma treatment, and then functional additives were sprayed by electrostatic spraying with parameters of 30kV voltage, 0.3mm nozzle diameter, 0.5mL / min flow rate, and 15cm distance.

[0054] Then dry at 60℃ for 3 minutes; finally, at a wavelength of 365nm and an energy density of 600mJ / cm². 2 The leather is UV-cured under light to obtain easy-to-clean sheepskin.

[0055] Example 3

[0056] Preparation of functional additives:

[0057] Dissolve 5 parts of sodium lignin sulfonate completely in 95 parts of tetrahydrofuran and stir until clear and transparent to obtain a lignin solution; then, under high-speed shearing at 8000 rpm, add the lignin solution dropwise to 200 parts of deionized water to obtain a crude solution.

[0058] S2. The crude liquid was transferred to a 3500 Da dialysis bag and dialyzed in flowing deionized water for 48 hours to completely remove THF and impurities. Then it was concentrated to obtain a lignin nanoparticle dispersion with a solid content of 2.5%.

[0059] S3. In a light-proof container, dissolve 3 parts of polydimethylsiloxane, 0.1 parts of palm wax and 0.5 parts of silane coupling agent in 50 parts of ethyl acetate and stir until homogeneous. Then slowly add 50 parts of lignin nanoparticle dispersion and continue stirring. Finally, add 1 part of photoinitiator and stir until completely dissolved to obtain the functional additive.

[0060] Surface modification:

[0061] The semi-finished sheepskin was subjected to low-temperature plasma treatment, and then functional additives were sprayed by electrostatic spraying with parameters of 50kV voltage, 0.5mm nozzle diameter, 0.5mL / min flow rate, and 20cm distance.

[0062] Then dry at 60℃ for 3 minutes; finally, at a wavelength of 365nm and an energy density of 800mJ / cm². 2 The leather is UV-cured under light to obtain easy-to-clean sheepskin.

[0063] Comparative Example 1

[0064] Preparation of functional additives:

[0065] Dissolve 3 parts of polydimethylsiloxane, 0.5 parts of palm wax and 0.5 parts of silane coupling agent in 55 parts of ethyl acetate and stir until homogeneous. Finally, add 10 parts of nano-silica and 1 part of photoinitiator and stir until completely dissolved to obtain the functional additive.

[0066] Surface modification:

[0067] The semi-finished sheepskin was subjected to low-temperature plasma treatment, and then the functional additives were sprayed by electrostatic spraying with the following parameters: voltage 40kV, spray gun diameter 0.4mm, flow rate 0.5mL / min, and distance 18cm.

[0068] Then dry at 60℃ for 3 minutes; finally, at a wavelength of 365nm and an energy density of 700mJ / cm². 2 The leather is UV-cured under light to obtain easy-to-clean sheepskin.

[0069] Comparative Example 2

[0070] This proportion does not include palm wax.

[0071] Preparation of functional additives:

[0072] Dissolve 3 parts sodium lignin sulfonate completely in 97 parts tetrahydrofuran and stir until clear and transparent to obtain a lignin solution; then, under high-speed shearing at 9000 rpm, add the lignin solution dropwise to 200 parts deionized water to obtain a crude solution;

[0073] S2. The crude liquid was transferred to a 4000 Da dialysis bag and dialyzed in flowing deionized water for 48 hours to completely remove THF and impurities. Then it was concentrated to obtain a lignin nanoparticle dispersion with a solid content of 2.5%.

[0074] S3. In a light-proof container, dissolve 3 parts of polydimethylsiloxane and 0.5 parts of silane coupling agent in 55 parts of ethyl acetate, stir until homogeneous, then slowly add 45 parts of lignin nanoparticle dispersion while stirring continuously, and finally add 1 part of photoinitiator and stir until completely dissolved to obtain the functional additive.

[0075] Surface modification:

[0076] The semi-finished sheepskin was subjected to low-temperature plasma treatment, and then the functional additives were sprayed by electrostatic spraying with the following parameters: voltage 40kV, spray gun diameter 0.4mm, flow rate 0.5mL / min, and distance 18cm.

[0077] Then dry at 60℃ for 3 minutes; finally, at a wavelength of 365nm and an energy density of 700mJ / cm². 2 The leather is UV-cured under light to obtain easy-to-clean sheepskin.

[0078] Experimental Example 1

[0079] Hydrophobicity was tested (GB / T 30693-2014). Using a contact angle meter, 5 μL of deionized water droplets were placed at different locations on the sample surface, and the static contact angle (WCA) was measured and averaged. A tiltable platform was used to measure the roll-off angle (SA) at which the droplet just began to roll.

[0080] The test results are shown in Table 1.

[0081] Table 1

[0082] sample Contact angle (WCA) Roll angle (SA) Example 1 158° 4° Example 2 158° 5° Example 3 157° 4.5° Comparative Example 1 124° 28° Comparative Example 2 146° 15° Unmodified 0° N / A

[0083] As shown in Table 1, the easy-to-clean sheepskin prepared in Examples 1-3 of this invention all exhibit excellent superhydrophobic properties, with water contact angles greater than 155° and roll-off angles less than 5°, making it easy for water droplets to roll off. Comparative Example 1, using conventional nano-SiO2, showed significantly lower hydrophobic properties (WCA = 124°) compared to the micro / nano structure constructed from lignin nanoparticles in this invention. Comparative Example 2, without the addition of palm wax, showed a significant decrease in hydrophobicity and roll-off properties (WCA = 146°, SA = 15°), demonstrating that the synergistic effect of palm wax and lignin nanoparticles is crucial for achieving superhydrophobicity.

[0084] Experiment Example 2

[0085] Durability test

[0086] Abrasion resistance: Following the QB / T 2726-2005 standard, the sample was subjected to 5000 abrasion cycles using a Martindale abrasion tester at a pressure of 9 kPa. The water contact angle of the sample surface after abrasion was then tested.

[0087] Scrub resistance: In accordance with GB / T 420-2009 standard, a scrub resistance tester (model: MODEL 935, ATLAS, USA) was used with a load of 500g for repeated scrubbing. The number of scrubbing cycles required to achieve coating damage (loss of hydrophobicity, WCA < 120°) was recorded.

[0088] The test results are shown in Table 2.

[0089] Table 2

[0090] sample Wear-resistant WCA (5000 cycles) Washability (number of washes) Example 1 152° 11573 Example 2 150° 11247 Example 3 151° 11364 Comparative Example 1 105° 6226 Comparative Example 2 118° 4379 Unmodified N / A N / A

[0091] After 5000 abrasion tests, the samples of this invention maintained good superhydrophobic properties, with a WCA greater than 150°, and exhibited excellent scrubbing resistance, exceeding 10,000 cycles. This indicates that the coating reinforced by the silane coupling agent and crosslinked by UV curing possesses excellent adhesion and durability. Comparative Examples 1 and 2 showed significantly poorer durability, demonstrating the overall synergistic effect of the formulation system of this invention.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing easy-to-clean sheepskin leather, characterized in that, Includes the following steps: The semi-finished sheepskin is subjected to low-temperature plasma treatment, then electrostatic spraying of functional additives, and finally pre-drying and UV curing to obtain easy-to-clean sheepskin.

2. The preparation method according to claim 1, characterized in that, The electrostatic spraying parameters are: voltage 30-50kV, spray gun diameter 0.3-0.5mm, flow rate 0.5mL / min, and distance 15-20cm.

3. The preparation method according to claim 1, characterized in that, The preparation method of the functional additive is as follows: S1. Completely dissolve sodium lignin sulfonate in tetrahydrofuran and stir until clear and transparent to obtain a lignin solution; then, under high-speed shear, add the lignin solution dropwise to deionized water to obtain a crude solution; S2. Transfer the crude liquid to a dialysis bag and dialyze it in flowing deionized water for 48 hours to completely remove THF and impurities. Then concentrate the solution to obtain a lignin nanoparticle dispersion with a solid content of 2.5%. S3. In a light-proof container, dissolve polydimethylsiloxane, palm wax and silane coupling agent in ethyl acetate and stir until homogeneous. Then slowly add lignin nanoparticle dispersion and continue stirring. Finally, add photoinitiator and stir until completely dissolved to obtain functional additive.

4. The preparation method according to claim 3, characterized in that, The mass ratio of sodium lignosulfonate, tetrahydrofuran, and deionized water in S1 is (1-5):(95-99):

200.

5. The preparation method according to claim 3, characterized in that, The high-speed shear rate in S1 is 8000-10000 rpm.

6. The preparation method according to claim 3, characterized in that, The molecular weight cutoff in the dialysis bag of S2 is 3500-5000 Da.

7. The preparation method according to claim 3, characterized in that, The mass ratio of polydimethylsiloxane, palm wax, silane coupling agent, ethyl acetate, lignin nanoparticle dispersion, and photoinitiator in S3 is 3:(0.1-1):0.5:(50-60):(40-50):

1.

8. The preparation method according to claim 1, characterized in that, The pre-drying temperature is 60°C, and the drying time is 3 minutes.

9. The preparation method according to claim 1, characterized in that, The UV curing wavelength is 365nm, and the energy density is 600-800mJ / cm². 2 .

10. An easy-to-clean sheepskin leather, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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