Super-hydrophobic PVC artificial leather and preparation method thereof

Abstract

The invention discloses super-hydrophobic PVC artificial leather and a preparation method thereof, and relates to the technical field of artificial leather, the super-hydrophobic PVC artificial leather specifically comprises a base cloth layer, a PVC base material layer, a micro-nano rough layer and a low-surface-energy composite coating which are sequentially arranged from bottom to top, and the micro-nano rough layer comprises the following raw materials in parts by mass: 3-5 parts of modified SiO2 nanoparticles (the particle size is 50nm, and the modified SiO2 nanoparticles are treated by a silane coupling agent) and 1 part of a water-based PU adhesive; the raw material of the low-surface-energy composite coating is a solution with the solid content of 20% prepared by dissolving PDMS and bio-based palm wax (with the mass ratio of 3.0 + / -10%: 1.0) in ethyl acetate. The artificial leather has the super-hydrophobic capacity, the contact angle is larger than or equal to 158 degrees, the rolling angle is smaller than or equal to 5 degrees, the environment durability is excellent, the bio-based wax (palm wax and the like) and polydimethylsiloxane (PDMS) composite coating is adopted, and the artificial leather does not contain persistent organic pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial leather, and specifically to a superhydrophobic PVC artificial leather and a preparation method thereof. Background Art

[0002] 1. Problems in the prior art Traditional PVC artificial leather has insufficient hydrophobicity: The contact angle of the ordinary PVC surface is usually <90°, which is easily wetted by water, leading to problems such as stain penetration and mildew.

[0003] Poor coating durability: Existing hydrophobic coating PVCs (such as pure fluorosilane coatings) are prone to peeling off after bending or friction, and the contact angle decreases significantly (for example, after 500 times of taber abrasion, the contact angle drops from 140° to below 120°).

[0004] Environmental protection defects: Traditional processes rely on fluorine-containing compounds (such as PFOA), which pose a risk of bioaccumulative toxicity and do not conform to the trend of green manufacturing.

[0005] 2. Industry requirements In the fields of medical treatment, automotive interiors, etc., there is a need for environmentally friendly PVC artificial leather with superhydrophobicity, flexibility, and durability. Summary of the Invention

[0006] To achieve the above object, the present invention provides the following technical solution: A superhydrophobic PVC artificial leather, comprising a base fabric layer, a PVC substrate layer, a micro-nano rough layer, and a low surface energy composite coating arranged in sequence from bottom to top; The raw materials of the micro-nano rough layer include 3-5 parts by weight of modified SiO2 nanoparticles and 1 part of water-based PU adhesive. The particle size of the modified SiO2 nanoparticles is 50nm and they are treated with a silane coupling agent; The raw material of the low surface energy composite coating is a solution with a solid content of 20% prepared by dissolving PDMS and bio-based palm wax in ethyl acetate at a mass ratio of 3.0±10% : 1.0.

[0007] The preparation method of the above superhydrophobic PVC artificial leather comprises the following steps: S1 Pretreatment of the substrate layer and the base fabric layer: Mix 68wt% PVC resin, 30wt% plasticizer DPHP, and 2wt% calcium-zinc stabilizer, and form a substrate with a thickness of 0.5mm by a calender. At a molten state of 160, it is bonded to the base fabric layer under a pressure of 30kg; Construction of S2 micro-nano rough layer: Modified SiO2 nanoparticles (particle size 50nm, treated with silane coupling agent) and waterborne PU adhesive were mixed at a mass ratio of 4.0±10%:1.0, and evenly coated on the surface of the substrate layer by electrostatic spraying (voltage 30kV, flow rate 0.5mL / min), and dried at 80°C for 10 minutes to form a rough layer with a thickness of 10μm - 15μm; Preparation of S3 low surface energy composite coating: PDMS and bio-based palm wax were dissolved in ethyl acetate at a mass ratio of 3.0±10%:1.0 to prepare a solution with a solid content of 20%. The solution was applied to the surface of the micro-nano rough layer by roll coating, with a coating amount of 20 - 25g / m², and cured by ultraviolet light, with a wavelength of 320 - 400nm and an energy density of 400 - 600mJ / cm 2 , forming a composite coating; S4 Embossing: The PVC substrate with the coating was embossed on the surface by a roller embossing process to form a bionic micro-structure for enhancing hydrophobicity.

[0008] Compared with the prior art, the beneficial effects of the present invention are: 1. Superhydrophobic and self-cleaning ability, contact angle ≥158°, rolling angle ≤5°, water droplets can quickly roll off on the inclined surface and carry away stains, reducing the risk of liquid penetration. Compared with traditional hydrophobic PVC (contact angle ≤140°, rolling angle ≥10°), the droplet adhesion force is significantly reduced, and pollutants such as dust and oil stains are not easily retained, achieving efficient self-cleaning.

[0009] 2. Excellent environmental durability, wear resistance: After 500 times of Taber wear, the contact angle ≥152° (ordinary PU coating <60°), rolling angle ≤5.5°, and the friction resistance performance is improved. Aging resistance: The performance remains basically unchanged after ultraviolet / humid heat aging.

[0010] 3. Non-fluorinated and green formula, abandoning fluorosilanes (such as PFOA / PFOS), using a composite coating of bio-based wax (such as palm wax) + polydimethylsiloxane (PDMS), without persistent organic pollutants, and the energy consumption of ultraviolet curing is lower than that of traditional thermal curing. Description of the Drawings

[0011] Figure 1 It is a schematic diagram of the material structure of the present invention.

[0012] In the figure: 1. Low surface energy composite coating; 2. Micro-nano rough layer; 3. PVC substrate layer; 4. Base cloth layer. Detailed Embodiments

[0013] The materials appearing in the present invention are provided with the manufacturers and grades as shown in Table 1 below: Table 1

[0014] Example 1 A superhydrophobic PVC artificial leather comprises a base fabric layer, a base material layer, a micro-nano rough layer, and a low surface layer composite coating, which are arranged in sequence from bottom to top. The material formula and preparation method are as follows: I. Pretreatment of the base material layer and the base fabric layer Material preparation PVC resin: PVC resin is selected, and the addition amount is 68wt% as the main component of the base material layer.

[0015] Plasticizer: The addition amount of the plasticizer is 30wt%, which improves the flexibility of the base material.

[0016] Stabilizer: The addition amount of calcium-zinc stabilizer is 2wt%, which prevents thermal degradation during the processing.

[0017] Base fabric layer: 75D 28-needle mesh double-sided white knitted fabric, with a thickness of about 0.4mm, providing mechanical support.

[0018] Forming process Mix the PVC resin, plasticizer, and stabilizer in proportion, and form a 0.5mm thick base material layer by calendering at 160°C in a molten state.

[0019] Under a pressure of 30 kg, bond the molten PVC base material with the base fabric layer to form a "base fabric layer - PVC base material layer" composite substrate.

[0020] II. Construction of the micro-nano rough layer Raw material ratio Modified SiO2 nanoparticles: with a particle size of 50nm, surface-treated with a silane coupling agent, and mixed with an aqueous PU adhesive in a mass ratio of (3 - 5):1 (Example 1 uses 3:1).

[0021] Coating process Electrostatic spraying: Use a voltage of 30 kV and a flow rate of 0.5 mL / min to evenly spray the mixed solution on the surface of the PVC base material layer to form a wet coating.

[0022] Drying and curing: Dry the coating at 80°C for 10 minutes to form a micro-nano rough layer with a thickness of 15 - 20μm, and improve the surface roughness through a multi-level rough structure.

[0023] III. Preparation of the low surface energy composite coating Raw material ratio PDMS (polydimethylsiloxane), mixed with bio-based palm wax in a mass ratio of (3 ± 10%):1, dissolved in ethyl acetate solvent, and formulated into a solution with a solid content of about 20%.

[0024] Coating and curing Roll coating process: The coating amount is controlled at 20 - 25 g / m² (20 g / m² is used in Example 1), and it is evenly coated on the surface of the rough layer.

[0025] UV curing: A UV light source of 320 - 400 nm (a wavelength of 365 nm is used in Example 1), with an energy density of 400 - 600 mJ / cm 2 (500 mJ / cm² is selected in Example 1), and a low surface energy composite coating with a thickness of 10 - 15 μm is formed by curing.

[0026] IV. Bionic microstructure embossing Process parameters: The roller embossing process is adopted to press bionic microstructures such as lotus leaf - like concave - convex textures on the coating surface, and the hydrophobic performance is further improved by simulating natural super - hydrophobic surfaces.

[0027] Mechanism of action: The microstructures and the rough layer act synergistically to form a "multi - level roughness + low surface energy" composite interface, reducing the contact area between the liquid droplet and the surface and improving the rollability.

[0028] Example 2 The difference from Example 1 is only that the modified SiO2 nanoparticles and the water - borne PU binder are mixed at a mass ratio adjusted to 5:1.

[0029] Example 3 The difference from Example 1 is only that the coating amount is controlled at 25 g / m², and a UV light source of 400 nm is used for UV curing, with an energy density of 600 mJ / cm 2 .

[0030] Comparative Example 1 Ordinary PU polyurethane coating materials on the market, such as polyurethane XH - PU319.

[0031] Comparative Example 2 A pure fluorosilane - coated hydrophobic PVC coating material, with the brand Stahl and the grade EVO WF - 3800.

[0032] Comparative Example 3 The difference from Example 1 is only that the micro - nano rough layer is missing.

[0033] Next, the materials of Example 1, 2, 3 and Comparative Example 1, 2, 3 are subjected to experimental tests, mainly testing the hydrophobic performance in the initial state, the hydrophobic performance after abrasion, and the hydrophobic performance after long - term environmental aging. Among them, the hydrophobic performance is mainly reflected by two indicators: static contact angle and rolling angle.

[0034] 1) Static contact angle test Standard basis: GB / T 30693-2014 "Determination method for water contact angle of plastic surface".

[0035] Instrument: Contact angle measuring instrument (such as Krüss DSA series).

[0036] Rolling angle test Standard basis: GB / T 30693-2014 "Determination method for water contact angle of plastic surface".

[0037] Instrument: Adjustable tilting platform + contact angle measuring instrument.

[0038] Steps: Fix the sample on the tilting platform, drop 10 μL of deionized water droplet, slowly increase the tilting angle of the platform, and record the critical angle (rolling angle) when the droplet starts to roll.

[0039] 2) Hydrophobic property test after abrasion resistance Standard basis: QBT 4043-2010 "Automotive polyvinyl chloride artificial leather" (6.25 Taber abrasion).

[0040] Instrument: Taber abrasion tester (CS-10 grinding wheel, load 1000 g).

[0041] Steps: Conduct 500-cycle wear test on the sample. After the test, re-measure the contact angle and rolling angle according to the above method, and calculate the performance retention rate.

[0042] 3) Hydrophobic property test after long-term environmental aging Refer to GB / T 16422.3-2014, use QUV ultraviolet aging chamber (UVA-340 lamp tube, irradiation intensity 0.76 W / m², 60 °C / 8 h light + 50 °C / 4 h condensation, cycle 400 hours).

[0043] Wet heat aging: Place the sample in an environment of 85 °C and 85% relative humidity for 240 hours. Test the contact angle and rolling angle after aging.

[0044] Statistically fill in the relevant test data of the materials in Examples 1, 2, 3 and Comparative Examples 1, 2, 3 in Table 2 below.

[0045] Table 2

[0046] As shown in the above table, under the condition of reasonably adjusting the formula and process, Examples 1, 2, 3 can maintain stable performance. Combining Example 1 and Comparative Example 3, it can be seen that after adding the micro-nano rough layer, the contact angle of the material after abrasion resistance is larger, the rolling angle is smaller, and the hydrophobic property is better. Combining Comparative Examples 1, 2, 3, it can be seen that the low surface energy composite coating has better hydrophobicity than other coatings.

[0047] The above are only the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

[0048] Matters not described in detail in the present invention are all well-known technologies to those skilled in the art.

Claims

1. A superhydrophobic PVC artificial leather, characterized in that, It includes a base fabric layer, a PVC substrate layer, a micro-nano rough layer, and a low surface energy composite coating which are arranged successively from bottom to top; the raw materials of the micro-nano rough layer include 3-5 parts by weight of modified SiO2 nanoparticles and 1 part of waterborne PU adhesive, the particle size of the modified SiO2 nanoparticles is 50 nm, and they are treated with a silane coupling agent; the raw materials of the low surface energy composite coating are PDMS and bio-based palm wax dissolved in ethyl acetate in a mass ratio of 3.0±10% : 1.0 to form a solution with a solid content of 20%.

2. A preparation method of the superhydrophobic PVC artificial leather as described in claim 1, characterized in that: It includes the following steps: S1 Pretreatment of the substrate layer and the base fabric layer: Mix 68 wt% PVC resin, 30 wt% plasticizer DPHP, and 2 wt% stabilizer calcium zinc, and form a substrate with a thickness of 0.5 mm through a calender. At a molten state of 160 °C, bond it with the base fabric layer under a pressure of 30 kg; S2 Construction of the micro-nano rough layer: Mix modified SiO2 nanoparticles with a particle size of 50 nm, which are treated with a silane coupling agent, and waterborne PU adhesive in a mass ratio of 4.0±10%:1.0, and uniformly coat the surface of the substrate layer by electrostatic spraying with a voltage of 30 kV and a flow rate of 0.5 mL / min, and dry it at 80 °C for 10 minutes to form a rough layer with a thickness of 10 μm to 15 μm; Preparation of S3 low surface energy composite coating: PDMS and bio-based palm wax are dissolved in ethyl acetate at a mass ratio of 3.0 ± 10% : 1.0 to form a solution with a solid content of 20%. The solution is applied to the surface of the micro-nano rough layer by a roll coating process with a coating amount of 20 - 25 g / m² and then cured by ultraviolet light with a wavelength of 320 - 400 nm and an energy density of 400 - 600 mJ / cm². 2 , forming a composite coating; S4 Embossing: Use the roller embossing process on the PVC substrate after the coating is done to form a bionic micro-structure on the surface to improve the hydrophobicity.

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