Coating material for silicone and fiber cloth composite and composite forming process

Abstract

The application discloses a coating material for silicone and fiber cloth composite and a forming process. The coating material comprises a bottom layer and a thin layer, the bottom layer contains modified hydrogen-containing silicone oil A (containing polyether and quaternary ammonium salt), the thin layer contains modified hydrogen-containing silicone oil B (containing epoxy group) and modified white carbon black. Through gradient vulcanization of the semi-cured bottom layer and the fully-cured thin layer, a release paper is not needed, the production process is simplified, the cost is low, and environmental protection is good. The coating material has good weather resistance, soft hand feeling and clear surface patterns, and solves the problems of poor interface bonding force, insufficient wear resistance, difficult consideration of hand feeling and mechanical properties and limited decoration of the existing silicone leather.

Description

Technical Field

[0001] This invention belongs to the technical field of silicone materials, and relates to a coating material for a silicone and fiber cloth composite and a composite molding process. Background Technology

[0002] Silicone rubber, with its outstanding advantages such as good air permeability, non-toxicity and environmental friendliness, resistance to high and low temperatures, excellent weather resistance, and soft feel, is gradually gaining attention in the leather industry and is gradually replacing traditional polyurethane (PU) and polyvinyl chloride (PVC) artificial leather. However, existing silicone leather still faces several key technical bottlenecks in practical applications, which seriously restrict its large-scale promotion and application.

[0003] In existing silicone leather manufacturing processes, release paper transfer coating or lamination methods are commonly used. The use of release paper adds multiple steps such as coating, lamination, and peeling, resulting in a lengthy production process, high equipment investment, and limited production efficiency. Low surface energy makes it difficult for silicone rubber coatings to fully wet the surface and fiber gaps of fiber cloth substrates (such as nylon, polyester, cotton, etc.), thus failing to form effective physical anchoring.

[0004] In addition, silicone leather also suffers from the problem of balancing feel and mechanical properties, and the feel (softness, smoothness, and skin-friendliness) of silicone leather is an important indicator for evaluating its quality. In the prior art, for example, the patent with publication number CN113174761B improves mechanical properties by introducing phenyl silicone rubber and fluorinated particles, but fails to solve the problems of poor interfacial bonding and limited surface decoration.

[0005] Therefore, there is an urgent need for a silicone leather coating material and molding process that can simultaneously achieve strong interfacial bonding, good mechanical properties, and a soft feel. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a coating material for silicone and fiber cloth composites and a composite forming process.

[0007] A coating material for a silicone and fiber cloth composite is disposed on the surface of a fiber cloth substrate, the coating material comprising an underlayer and a thin layer disposed on the surface of the underlayer; The underlayer, by weight, comprises the following components: 40-60 parts of modified hydrogen-containing silicone oil A, 15-25 parts of vinyl MQ resin, 5-10 parts of MQ hydrogen-containing resin and / or MDQ hydrogen-containing resin, 0.001-0.005 parts of inhibitor, and 0.002-0.006 parts of platinum catalyst. The thin-layer coating, by weight, comprises the following components: 40-52 parts of modified hydrogen-containing silicone oil B, 20-24 parts of vinyl MQ resin, 2-5 parts of pigment, 6-9 parts of MQ hydrogen-containing resin and / or MDQ hydrogen-containing resin, 4-6 parts of modified silica, 0.001-0.002 parts of inhibitor, and 0.002-0.003 parts of platinum catalyst; The modified hydrogen-containing silicone oil A is a product of the hydrosilylation reaction of hydrogen-containing silicone oil with allyl polyether and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), wherein the Si-H bond conversion rate is 40-60%. The modified hydrogen-containing silicone oil B is a product of the hydrosilylation reaction between hydrogen-containing silicone oil and allyl glycidyl ether, wherein the Si-H bond conversion rate is 40-60%. The modified silica is fumed silica that has been hydrophobically modified by a silane coupling agent containing double bonds.

[0008] Furthermore, the viscosity of the underlying coating is 50,000-200,000 mPa·s.

[0009] Furthermore, the pigment is one or more of titanium dioxide, carbon black, iron oxide red, iron oxide yellow, phthalocyanine blue, and phthalocyanine green.

[0010] Furthermore, the silane coupling agent containing double bonds is vinyltrimethoxysilane or methacryloxypropyltrimethoxysilane (KH570).

[0011] Further, the inhibitor is one or more of methylbutynol, ethynylcyclohexanol, or polyvinylpolysiloxane; the platinum catalyst is a chloroplatinic acid-divinyltetramethyldisiloxane complex (Karstedt catalyst) with a Pt content of 3000-5000 ppm.

[0012] Further, the preparation process of the modified hydrogen-containing silicone oil A includes: adding 100 parts of hydrogen-containing silicone oil (hydrogen content 0.3-0.8%, viscosity 500-2000 cs), 5-10 parts of allyl polyether (molecular weight 400-800), and 3-8 parts of METAC ([2-(methacryloyloxy)ethyl]trimethylammonium chloride, 75% aqueous solution, purified) to a reactor, replacing the air with nitrogen, adding 0.01-0.02 parts of platinum catalyst and 0.005-0.01 parts of inhibitor, heating to 80-100℃, stirring for 4-6 hours, controlling the Si-H bond conversion rate to 40-60%, and removing unreacted substances and water by vacuum distillation to obtain the modified hydrogen-containing silicone oil A.

[0013] Further, the preparation process of the modified hydrogen-containing silicone oil B includes: adding 100 parts of hydrogen-containing silicone oil (hydrogen content 0.3-0.8%, viscosity 500-2000 cs) and 5-10 parts of allyl glycidyl ether to a reactor, replacing the air with nitrogen, adding 0.01-0.02 parts of platinum catalyst and 0.005-0.01 parts of inhibitor, heating to 80-100℃, stirring and reacting for 4-6 hours, controlling the Si-H bond conversion rate to 40-60%, and removing unreacted substances by vacuum distillation to obtain the modified hydrogen-containing silicone oil B.

[0014] Furthermore, the preparation process of the modified silica includes: fumed silica (specific surface area 150-300 m²) is reacted with fumed silica. 2 Mix 10-12 parts of a silane coupling agent containing double bonds with 1.6-2.0 parts of a 40 wt% ethanol aqueous solution, add to 80-100 parts of the solution, ultrasonically disperse for 45-60 minutes, adjust the pH to 9.0-11.0, reflux at 65-70℃ for 5-6 hours, centrifuge, wash with anhydrous ethanol, and vacuum dry at 80℃ to constant weight to obtain modified silica.

[0015] The present invention also provides a molding process for a silicone and fiber cloth composite, comprising the following steps: (1) Undercoating and semi-curing: Mix the components of the undercoating evenly, adjust the viscosity to 50,000-200,000 mPa·s, and apply it to the surface of the fiber cloth substrate by scraper coating or roller coating. The coating thickness is 0.05-0.15 mm. Heat at 80-120℃ for 1-3 minutes to partially vulcanize the undercoating to a semi-cured state where the surface is not sticky but still has viscoelasticity, thus obtaining a semi-cured undercoating.

[0016] (2) Thin-layer coating and curing: Mix the components of the thin-layer coating evenly and apply it to the surface of the semi-cured substrate. The coating thickness is 0.02-0.08 mm. Heat at 100-140℃ for 5-10 minutes to allow the thin-layer coating to fully cure. The entire curing process does not require the assistance of release paper for transfer or bonding.

[0017] The beneficial effects of this invention are: The modified hydrogen-containing silicone oil A in the underlayer significantly enhances the wettability and interfacial adhesion between the coating and the fiber fabric substrate by introducing polyether segments and quaternary ammonium salt groups (METAC). The polyether segments reduce surface tension, promoting the coating's penetration into the fiber gaps to form a physical anchor; the quaternary ammonium salt groups, carrying a positive charge, can form a strong electrostatic interaction with the negatively charged groups on the surface of the fiber fabric substrate. Simultaneously, a gradient vulcanization process using a semi-cured underlayer and a fully cured thin layer allows the residual Si-H on the underlayer surface and the Si-Vi in the thin layer to continue hydrosilylation during secondary curing, forming covalent bonds between the layers. This significantly enhances the interlayer adhesion and prevents the coating from peeling off.

[0018] The modified hydrogen-containing silicone oil B in the thin layer introduces epoxy groups, which can chemically bond with the silanol groups on the surface of the modified silica, enhancing the filler-matrix interface. Simultaneously, the vinyl groups grafted onto the modified silica surface participate in hydrosilylation crosslinking, improving mechanical properties. Furthermore, the silicone rubber matrix itself has a low elastic modulus, which, combined with the plasticizing effect of the polyether segments and moderate crosslinking, results in a leather feel that is soft, smooth, and skin-friendly.

[0019] More importantly, this invention employs a direct coating process to sequentially apply a base coat and a thin coat to the surface of a fiber cloth substrate, eliminating the need for release paper as a carrier or release layer during the entire curing process. Compared to existing technologies that commonly use release paper for transfer coating or lamination, this invention eliminates the consumption, peeling, and disposal of release paper, significantly reducing material costs and waste generation, simplifying the production process, and improving production efficiency. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0021] Preparation Example 1: Preparation of Modified Hydrogen-Containing Silicone Oil A 100 parts of hydrogen-containing silicone oil (0.5% hydrogen content, viscosity 1000 cs), 8 parts of allyl polyether (molecular weight 600), and 6 parts of METAC ([2-(methacryloyloxy)ethyl]trimethylammonium chloride, 75% aqueous solution, purified) were added to a reactor. Nitrogen gas was introduced to replace the air. 0.015 parts of Karstedt platinum catalyst (Pt content 5000 ppm) and 0.008 parts of ethynylcyclohexanol were added. The temperature was raised to 90℃, and the reaction was stirred for 5 hours. The Si-H bond conversion rate was measured (using infrared spectroscopy or chemical gasification method), and the conversion rate was controlled at 50% ± 5%. After the reaction, unreacted substances and water were removed by vacuum distillation to obtain modified hydrogen-containing silicone oil A.

[0022] Preparation Example 2: Preparation of Modified Hydrogen-Containing Silicone Oil B 100 parts of hydrogen-containing silicone oil (0.5% hydrogen content, viscosity 1000 cs) and 6 parts of allyl glycidyl ether were added to a reactor. Nitrogen gas was introduced to replace the air. 0.015 parts of Karstedt platinum catalyst (5000 ppm Pt content) and 0.008 parts of ethynylcyclohexanol were added. The temperature was raised to 90°C, and the reaction was stirred for 5 hours. The Si-H bond conversion rate was controlled at 50% ± 5%. After the reaction was completed, unreacted substances were removed by vacuum distillation to obtain modified hydrogen-containing silicone oil B.

[0023] Preparation Example 3: Preparation of Modified Silica Fumed silica (specific surface area 200 m²) 2 10 parts of ( / g) were mixed with 1.8 parts of vinyltrimethoxysilane and added to 90 parts of 40 wt% ethanol aqueous solution. The mixture was ultrasonically dispersed for 50 minutes, the pH was adjusted to 10.5 with ammonia, and the mixture was refluxed at 68°C for 5.5 hours. The mixture was then centrifuged, washed three times with anhydrous ethanol, and vacuum dried at 80°C to constant weight to obtain modified silica.

[0024] Example 1 Undercoat formulation (parts by weight): Modified hydrogen-containing silicone oil A (Preparation Example 1): 50 parts Vinyl MQ resin (vinyl content 3%, viscosity 5000 cs): 20 parts MQ hydrogen-containing resin (0.3% hydrogen content): 8 parts Ethynylcyclohexanol (inhibitor): 0.003 parts Karstedt platinum catalyst (5000 ppm): 0.004 parts Thin-layer coating formulation (parts by weight): Modified hydrogen-containing silicone oil B (Preparation Example 2): 46 parts Vinyl MQ resin (vinyl content 3%): 22 parts Titanium dioxide (rutile type): 4 parts MDQ hydrogen-containing resin (0.3% hydrogen content): 8 parts Modified silica (Preparation Example 3): 5 parts Ethynylcyclohexanol (inhibitor): 0.0015 parts Karstedt platinum catalyst (5000 ppm): 0.0025 parts Molding process: (1) Mix the base coat evenly, adjust the viscosity to 100,000 mPa·s, and apply it to the surface of the nylon fiber cloth substrate (thickness 0.5 mm) using a doctor blade coater. The coating thickness is 0.10 mm. Heat at 100°C for 2 minutes to form a semi-cured base coat.

[0025] (2) Mix the thin layer coating evenly and apply it to the surface of the semi-cured substrate with a coating thickness of 0.05 mm. Heat at 120°C for 8 minutes to allow the thin layer to fully cure.

[0026] Example 2 Undercoat formulation (parts by weight): Modified hydrogen-containing silicone oil A: 40 parts Vinyl MQ resin: 15 parts MQ hydrogen-containing resin: 5 parts Inhibitor: 0.001 parts Platinum catalyst: 0.002 parts Thin-layer coating formulation (parts by weight): Modified hydrogen-containing silicone oil B: 40 parts Vinyl MQ resin: 20 parts Titanium dioxide: 2 parts MQ hydrogen-containing resin: 6 parts Modified silica: 4 parts Inhibitor: 0.001 parts Platinum catalyst: 0.002 parts The forming process is the same as in Example 1. The substrate is polyester fiber cloth, the thickness of the bottom coating is 0.08 mm, the thickness of the thin coating is 0.04 mm, the semi-curing temperature is 90℃×2.5 min, and the curing temperature is 110℃×8 min.

[0027] Example 3 Undercoat formulation (parts by weight): Modified hydrogen-containing silicone oil A: 60 parts Vinyl MQ resin: 25 parts MDQ hydrogen-containing resin: 10 parts Inhibitor: 0.005 parts Platinum catalyst: 0.006 parts Thin-layer coating formulation (parts by weight): Modified hydrogen-containing silicone oil B: 52 parts Vinyl MQ resin: 24 parts Titanium dioxide: 5 parts MDQ hydrogen-containing resin: 9 parts Modified silica: 6 parts Inhibitor: 0.002 parts Platinum catalyst: 0.003 parts The molding process is the same as in Example 1. The substrate is cotton fiber cloth, the thickness of the bottom coating is 0.12 mm, the thickness of the thin coating is 0.06 mm, the semi-curing temperature is 110℃×1.5 min, and the curing temperature is 130℃×7 min.

[0028] Comparative Example 1 The difference from Example 1 is that unmodified hydrogen-containing silicone oil (0.5% hydrogen content, viscosity 1000 cs) is used instead of modified hydrogen-containing silicone oil A in the undercoat, meaning the undercoat does not contain polyether and quaternary ammonium salt modifying groups. The thin-layer coating is the same as in Example 1. All other process parameters are consistent with Example 1.

[0029] Comparative Example 2 The difference from Example 1 is that unmodified hydrogen-containing silicone oil (0.5% hydrogen content, viscosity 1000 cs) is used instead of modified hydrogen-containing silicone oil B in the thin-layer coating, meaning the thin layer does not contain epoxy-modified groups. The undercoat is the same as in Example 1. All other process parameters are consistent with Example 1.

[0030] Comparative Example 3 The difference from Example 1 is that: unmodified hydrogen-containing silicone oil (0.5% hydrogen content) is used instead of modified hydrogen-containing silicone oil A in the undercoat; and unmodified hydrogen-containing silicone oil (0.5% hydrogen content) is used instead of modified hydrogen-containing silicone oil B in the thin-layer coating. The remaining components and processes are the same as in Example 1.

[0031] Performance testing The silicone leathers prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The test methods and results are shown in Table 1.

[0032] Test method: Adhesion: According to GB / T 9286-1998 (cross-cut test), the substrate is nylon fiber cloth. Wear resistance: According to GB / T 1768-2021 (Taber wear), CS-10 grinding wheel, 500g load, speed 100 r / min, 1000 cycles of friction, record the wear amount. UV aging resistance: Refer to GB / T 1865-2009, xenon lamp aging, irradiation time 1000 h, irradiation intensity 0.5 W / m 2 (340 nm), adhesion tested after aging Tensile strength: According to GB / T 528-2009, Type II dumbbell-shaped cutter. Tear strength: According to GB / T 529-2008, right-angle cutting blade

[0033] As shown in Table 1, the adhesion of Examples 1-3 was all grade 0, and remained at grade 0 after UV aging, indicating excellent and durable adhesion between the coating and the fiber cloth substrate. The wear amount was only 4.1-4.4 mg, significantly better than the comparative examples (6.8-8.5 mg), proving that the synergistic effect of modified hydrogen-containing silicone oil A / B and modified silica improved the wear resistance. The tensile strength was ≥4.0 MPa, and the tear strength was ≥17.8 kN / m, indicating good mechanical properties. The adhesion of Comparative Example 1 (unmodified bottom layer) decreased to grade 2, and that of Comparative Example 3 (unmodified both layers) decreased to grade 3, proving that the polyether and quaternary ammonium salt in modified hydrogen-containing silicone oil A were crucial to the interfacial adhesion. Although the adhesion of Comparative Example 2 (unmodified thin layer) was grade 0, the wear amount increased to 6.8 mg, proving that the thin layer modification mainly contributed to the wear resistance.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A coating material for a silicone and fiber cloth composite, disposed on the surface of a fiber cloth substrate, characterized in that, The coating material includes an underlayer and a thin layer disposed on the surface of the underlayer; The underlying coating comprises the following components: modified hydrogen-containing silicone oil A, vinyl MQ resin, MQ hydrogen-containing resin and / or MDQ hydrogen-containing resin, inhibitor and platinum catalyst; The thin-film coating comprises the following components: modified hydrogen-containing silicone oil B, vinyl MQ resin, pigment, MQ hydrogen-containing resin and / or MDQ hydrogen-containing resin, modified silica, inhibitor and platinum catalyst. The modified hydrogen-containing silicone oil A is a product of the hydrosilylation reaction of hydrogen-containing silicone oil with allyl polyether and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), wherein the Si-H bond conversion rate is 40-60%. The modified hydrogen-containing silicone oil B is a product of the hydrosilylation reaction between hydrogen-containing silicone oil and allyl glycidyl ether, wherein the Si-H bond conversion rate is 40-60%. The modified silica is fumed silica that has been hydrophobically modified by a silane coupling agent containing double bonds.

2. The coating material for the organosilicon and fiber cloth composite according to claim 1, characterized in that, By weight, the undercoat comprises: 40-60 parts of modified hydrogen-containing silicone oil A, 15-25 parts of vinyl MQ resin, 5-10 parts of MQ hydrogen-containing resin and / or MDQ hydrogen-containing resin, 0.001-0.005 parts of inhibitor, and 0.002-0.006 parts of platinum catalyst.

3. The coating material for the organosilicon and fiber cloth composite according to claim 1, characterized in that, By weight, the thin-layer coating comprises: 40-52 parts of modified hydrogen-containing silicone oil B, 20-24 parts of vinyl MQ resin, 2-5 parts of pigment, 6-9 parts of MQ hydrogen-containing resin and / or MDQ hydrogen-containing resin, 4-6 parts of modified silica, 0.001-0.002 parts of inhibitor, and 0.002-0.003 parts of platinum catalyst.

4. The coating material for the organosilicon and fiber cloth composite according to claim 1, characterized in that, The viscosity of the underlying coating is 5-200,000 mPa·s.

5. The coating material for the organosilicon and fiber cloth composite according to claim 1, characterized in that, The silane coupling agent containing double bonds is vinyltrimethoxysilane or methacryloxypropyltrimethoxysilane.

6. The coating material for the organosilicon and fiber cloth composite according to claim 1, characterized in that, The inhibitor is one or more of methylbutynol and ethynylcyclohexanol; the platinum catalyst is a chloroplatinic acid-divinyltetramethyldisiloxane complex with a Pt content of 3000-5000 ppm.

7. A forming process for preparing an organosilicon and fiber cloth composite using the coating material according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Apply the base coat to the surface of the fiber cloth substrate and heat it at 80-120℃ for 1-3 minutes to form a semi-cured base coat; (2) Apply a thin layer of coating to the surface of the semi-cured substrate and heat it at 100-140℃ for 5-10 minutes to allow the thin layer of coating to fully cure.

8. The forming process according to claim 7, characterized in that, The coating thickness of the base coat in step (1) is 0.05-0.15 mm.

9. The forming process according to claim 7, characterized in that, The coating thickness of the thin-layer coating in step (2) is 0.02-0.08 mm.

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