Double-layer functional antibacterial hydrolysis-resistant high-elasticity synthetic leather and preparation process thereof

Abstract

The application discloses a double-layer functional antibacterial hydrolysis-resistant high-elasticity synthetic leather and a preparation process thereof. The synthetic leather comprises a high-elasticity base cloth formed by blending polyester fibers and castor fibers and a wet-process base layer formed by penetrating foaming slurry into the base cloth, and a foaming layer and a dry-process surface layer are sequentially stacked on the wet-process base layer. The foaming slurry comprises hydrolysis-resistant soft wet-process resin, antibacterial agent and other components; the foaming layer is formed by foaming resin containing isocyanate curing agent. The preparation method mainly comprises the following steps: base cloth preparation, foaming slurry preparation and vacuum degassing, wet-process base preparation, dry-process surface layer and foaming layer slurry preparation, and pasting of the surface layer and the foaming layer on release paper and then pasting with the wet-process base after coating, and aging. According to the double functional design of the base cloth and the coating and the application of water-based polyurethane foaming resin, the synthetic leather has excellent antibacterial property, hydrolysis resistance, high elasticity and air permeability, and has soft hand feeling, Q-elasticity and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of synthetic leather preparation technology, specifically to a double-layer synthetic leather with antibacterial, hydrolysis-resistant and high elasticity functions and its preparation process. Background Technology

[0002] As an important alternative to natural leather, synthetic leather has undergone several technological iterations since the 1960s, from early PVC artificial leather to polyurethane synthetic leather, and then to water-based polyurethane synthetic leather, with its simulation and physical properties continuously improving. However, existing synthetic leather products still have many technical bottlenecks, especially in terms of antibacterial properties, hydrolysis resistance, and hand elasticity, which are difficult to meet the ever-increasing market demands.

[0003] 1. Technical defects of existing synthetic leather Traditional synthetic leather is mainly divided into three categories: PVC synthetic leather, solvent-based polyurethane synthetic leather, and water-based polyurethane synthetic leather. While PVC synthetic leather has good weather resistance, it suffers from drawbacks such as an environmentally unfriendly production process, difficulty in degradation, poor elasticity, and cumbersome manufacturing processes. Solvent-based polyurethane synthetic leather requires large amounts of organic solvents such as dimethylformamide (DMF) during production, easily causing environmental pollution, and residual solvents may pose health risks. Water-based polyurethane synthetic leather solves the environmental problem, but its strength, hydrolysis resistance, and abrasion resistance are often poor, limiting its application in high-end fields.

[0004] In practical use, synthetic leather products are prone to hydrolysis due to prolonged exposure to varying temperatures and humidity, leading to a decline in their physical properties. Ester or ether bonds in the polyurethane molecular structure break under the influence of moisture and microorganisms, resulting in decreased strength and surface cracking. Simultaneously, the fine textures on the surface of synthetic leather easily accumulate dirt, becoming a breeding ground for bacteria and mold under suitable temperature and humidity conditions. This not only affects appearance and safety but also accelerates material aging and shortens service life. While existing technologies include adding antibacterial agents to improve the antibacterial properties of synthetic leather, chemical antibacterial agents suffer from poor heat resistance, easy migration, and short lifespan, and are prone to failure or loss during the high-temperature processing in synthetic leather manufacturing.

[0005] 2. Limitations of existing improvement technologies To improve the antibacterial properties of synthetic leather, the industry has tried various methods. For example, some technologies load chemical antibacterial agents onto a carrier before adding them to the synthetic leather coating. However, the carrier's loading effect on the antibacterial agent is unstable, and the antibacterial agent is prone to desorption or inactivation during high-temperature treatment. Other technologies use natural antibacterial agents such as modified chitosan, but simply adding antibacterial agents makes it difficult to simultaneously ensure the durability of the antibacterial effect and the stability of the material's physical properties.

[0006] To improve hydrolysis resistance, existing technologies often employ the addition of crosslinking agents (such as polycarbodiimide), which react with the carboxyl groups produced during polyurethane hydrolysis, thus slowing down the hydrolysis process. However, this method often negatively impacts the feel and elasticity of synthetic leather, leading to material stiffness and reduced comfort. Furthermore, ordinary synthetic leather often sacrifices elasticity in pursuit of strength, resulting in a stiff feel and a poor user experience.

[0007] 3. Industry Development Trends and Technological Gaps With consumption upgrades and increasingly stringent environmental regulations, the synthetic leather industry is rapidly developing towards functional and eco-friendly directions. Market demand for high-end synthetic leather with multiple functions such as antibacterial properties, hydrolysis resistance, and high elasticity is growing, particularly in sports footwear materials, home furnishings, and automotive seats. While existing technologies have made some progress in improving individual properties, how to synergistically enhance antibacterial properties, hydrolysis resistance, and elasticity while maintaining environmental advantages remains a key technical challenge for the industry.

[0008] In summary, developing a synthetic leather product that combines excellent antibacterial properties, hydrolysis resistance, high elasticity, and environmental friendliness not only aligns with industry development trends but also fills existing technological gaps, possessing significant market value and technological importance. This invention presents an innovative solution based on this background. Summary of the Invention

[0009] This invention addresses the aforementioned deficiencies in existing synthetic leather products, aiming to provide a double-layer functionalized antibacterial, hydrolysis-resistant, and highly elastic synthetic leather and its preparation process. Its primary objective is to overcome the problems of existing synthetic leather, such as stiffness, poor antibacterial properties, susceptibility to hydrolytic aging, and poor breathability. Specifically, this invention aims to solve the following technical problems: 1. How to significantly improve the antibacterial properties of synthetic leather and ensure the durability of its antibacterial effect; 2. How to effectively improve the hydrolysis resistance of synthetic leather and extend its service life in humid and hot environments; 3. How to ensure the above functions while giving synthetic leather an excellent elastic feel, high softness and comfortable touch; 4. How to optimize the material system and process flow to make the product have both good breathability and physical strength, while meeting environmental protection requirements.

[0010] To achieve the above objectives, the present invention adopts the following technical solution.

[0011] A dual-layer functionalized antibacterial and hydrolysis-resistant high-elasticity synthetic leather, characterized in that it comprises a high-elasticity wet-process base layer and a foaming layer and a dry-process surface layer sequentially stacked on the high-elasticity wet-process base layer.

[0012] The highly elastic wet-laid base layer is formed from a highly elastic base fabric and a foaming slurry that permeates and solidifies therein. The highly elastic base fabric is preferably an ultra-thin antibacterial base fabric made of a blend of polyester and castor fibers, with a thickness of 0.45 mm. The polyester fibers provide basic strength, while the castor fibers impart excellent breathability and softness to the base fabric.

[0013] The foaming slurry is prepared by mixing the following components in parts by weight and then vacuum degassing: Hydrolysis-resistant, flexible wet-process resin: 57 parts Solvent: 34 parts Ultrafine calcium carbonate: 12 parts Pulp powder: 14 parts Low modulus ultra-soft resin: 8 parts Antibacterial agent: 0.5 parts Water-based pigment: 0.6 parts Fabric softener: 0.9 parts Polyester-modified silicone-based ammonia oil: 0.8 parts The viscosity of the foaming slurry is controlled within the range of 9000-10000 cps.

[0014] The foamed layer is formed by foaming a slurry containing a foaming resin and an isocyanate curing agent. The amount of isocyanate curing agent added is 1-2% of the weight of the foaming resin. This foamed layer not only provides good elasticity, but its adhesion to the wet-process base also further enhances the overall water resistance of the product.

[0015] The dry-process surface layer is formed from a slurry containing water-based resin and color chips. The amount of color chips added is 3-8% of the weight of the water-based resin. This surface layer mainly provides the surface effect, color, and a certain degree of abrasion resistance of the final product.

[0016] Accordingly, the present invention also provides a preparation process for the above-mentioned synthetic leather, characterized by comprising the following steps: (1) Preparation of high elasticity base fabric: Provide a high elasticity base fabric made of polyester fiber and castor fiber blend.

[0017] (2) Preparation and vacuum degassing of foaming slurry: Mix and stir the hydrolysis-resistant soft wet-process resin, solvent, ultrafine calcium carbonate, pulp powder, low modulus ultrasoft resin, antibacterial agent, water-based pigment, softener, and polyester modified silicone ammonia oil according to the ratio, and perform vacuum degassing treatment. The degassing time is preferably 80 minutes to obtain foaming slurry with uniform viscosity.

[0018] (3) Preparation of wet-process base fabric: The high-elasticity base fabric is washed in room temperature water, ironed with ironing wheels to even out some of the moisture, and then coated with foaming slurry through a precision coating table. Then it is placed in a 15% coagulation solution for coagulation, so that the slurry can fully adhere to and penetrate into the base fabric. After that, it is washed with water, ironed with 12 wheels to fix the width and dried. Finally, it is cooled by a circulating cooling wheel and then rolled up to obtain the high-elasticity wet-process base fabric.

[0019] (4) Preparation of dry surface layer slurry: Add 3-8 parts of color flakes to 100 parts of water-based resin, stir and disperse evenly at a speed of 3000 rpm, and set aside.

[0020] (5) Preparation of foamed coating: Add a small amount of heavy filler to the foaming resin and stir to foam. During high-speed stirring, slowly add 1-2% of the weight of the foaming resin as isocyanate curing agent and perform uniform foaming treatment for later use.

[0021] (6) Dry lamination and curing: Apply a dry surface layer slurry to the deep-textured release paper, dry it, then apply a foaming layer slurry and dry it slowly in an oven at 70-85℃. Subsequently, cure it at 150℃ for 3 minutes, and then laminate it with the high-elasticity wet-laid base obtained in step 3. The laminated leather body is baked at 130℃ for 4-5 minutes for final curing, cooled, and then rolled up to obtain the antibacterial, hydrolysis-resistant, high-elasticity synthetic leather.

[0022] Compared with existing technologies, the double-layer functionalized antibacterial and hydrolysis-resistant high-elasticity synthetic leather and its preparation process provided by this invention have the following significant advantages: Superior antibacterial properties: By incorporating natural castor fiber with antibacterial properties into the base fabric blend and adding antibacterial agents to the wet foaming slurry, dual antibacterial protection is achieved for both the base fabric and the coating, effectively inhibiting the growth of bacteria and mold, and improving the hygiene, safety, and service life of the product.

[0023] Excellent hydrolysis resistance: The formulation uses a large amount of hydrolysis-resistant soft wet-process resin (57 parts) as the main material, and uses isocyanate curing agent for cross-linking and curing in the dry foaming layer, which significantly enhances the stability of the polyurethane molecular structure, making it less prone to breakage in humid and hot environments, thereby greatly improving the product's hydrolysis resistance.

[0024] Excellent feel and elasticity: The application of low-modulus ultra-soft resin (8 parts) and foaming resin, these anionic water-based resins are characterized by fast foaming speed and good strength, giving the synthetic leather a soft touch and excellent elasticity. At the same time, the softener and polyester-modified silicone ammonia oil in the formula further improve the smoothness and softness of the finished product.

[0025] Excellent breathability and physical properties: Utilizing an ultra-thin (0.45mm) high-elasticity base fabric blended from polyester and castor fibers, the fabric has a loose and delicate structure, resulting in excellent breathability. The multi-round ironing and precisely controlled coagulation process during wet-process base fabrication ensures uniform penetration and curing of the sizing agent within the base fabric, allowing the finished product to maintain both breathability and sufficient physical strength.

[0026] Environmental protection and safety: The entire technical solution mainly uses a water-based resin system, avoiding the extensive use of organic solvents (such as DMF), thus meeting the requirements of clean production and environmental friendliness. The product has strong wetting and adhesion, high fastness, and excellent overall performance. Attached Figure Description

[0027] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0028] To make the technical means, creative features, objectives, and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention.

[0029] Example 1 (Reference) Figure 1 ) 1. Raw materials and proportions This embodiment prepares an antibacterial, hydrolysis-resistant, and highly elastic synthetic leather suitable for high-end shoe materials. The specific raw materials and their weight ratios are shown in the table below:

[0030] 2. Preparation process steps Step 1: Preparation of High-Elasticity Wet-Process Bass (1) Base fabric preparation: Polyester fiber and castor fiber are blended at a mass ratio of 70:30 and woven into a high elastic ultra-thin base fabric with a thickness of 0.45 mm.

[0031] (2) Preparation and degassing of foaming slurry: In a reactor equipped with a stirrer and a vacuum device, 34 parts of DMF solvent, 0.6 parts of water-based black pigment, 12 parts of ultrafine calcium carbonate, 14 parts of pulp powder, 8 parts of low-modulus ultra-soft resin, 0.5 parts of silver ion antibacterial agent, 57 parts of hydrolysis-resistant soft wet-process resin, 0.9 parts of softener, and 0.8 parts of polyester-modified silicone-based ammonia oil were added sequentially. The mixture was stirred at 500 rpm for 40 minutes to ensure uniform mixing. Then, the vacuum system was turned on, and the mixture was degassed at a vacuum of -0.08 MPa for 80 minutes to obtain a foaming slurry with a viscosity of 9500 cps (measured using a Brookfield viscometer).

[0032] (3) Base fabric treatment and coating: At room temperature (25℃), the base fabric is washed in a clean water tank to remove surface impurities. Then, a set of ironing rollers is used to iron out the moisture in the base fabric evenly and dry some of the moisture to make the base fabric flat. The prepared foaming slurry is evenly coated onto the treated base fabric using a precision coating table.

[0033] (4) Coagulation and post-treatment: The base fabric coated with the slurry is introduced into a coagulation tank containing a 15% (w / w) DMF aqueous solution and held at 25°C for 3 minutes to allow the slurry to fully coagulate and penetrate into the base fabric. Then, it is thoroughly washed with clean water to remove any residual DMF. Next, it is ironed sequentially by 12 sets of ironing rollers to fix the width and dried in an oven at 120°C. Finally, it is cooled to room temperature (approximately 25°C) using a circulating cooling roller and then wound up to obtain the high-elasticity wet-process base fabric.

[0034] Step 2: Preparation of the dry lamination layer (1) Preparation of dry surface coating slurry: Add 100 parts of water-based resin (WPU-356) and 5 parts of color flakes to the dispersion tank. Stir and disperse at high speed of 3000 rpm for 30 minutes to obtain a uniform dry surface coating slurry for later use.

[0035] (2) Preparation of foamed coating: Add 100 parts of foaming resin and a small amount (about 3 parts) of heavy filler (ultrafine calcium carbonate) to another container, and start stirring at medium speed. During the stirring process, slowly add 1.5 parts (1.5% of the weight of foaming resin) of isocyanate curing agent, and then increase the speed to 2500 rpm and stir at high speed for 3 minutes to obtain foamed slurry, which is ready for use.

[0036] (3) Coating and bonding: Select release paper with deep texture (such as kraft paper) as the carrier.

[0037] Apply a layer of the dry surface slurry prepared in step 2.1 evenly to the release paper with a scraper, and then pre-dry it in an oven at 85°C for 1 minute.

[0038] Apply another layer of the foaming slurry prepared in step 2.2 onto the dried surface layer.

[0039] The semi-finished product coated with the foaming layer slurry is placed in a 75°C oven and slowly dried for 2 minutes to allow it to initially foam and set.

[0040] The semi-finished product that has been partially dried is transferred to an oven at 150°C and cured for 3 minutes to fully cure the foam layer and increase its strength.

[0041] The high-elasticity wet-process base prepared in step one is bonded to the above-mentioned cured semi-finished product (foamed layer side) using a pressure roller under a pressure of 0.5 MPa.

[0042] The bonded synthetic leather is then placed in a 130°C oven and baked for 4.5 minutes to complete the final curing and ensure the strong bond between the layers.

[0043] (4) Cooling and winding: After the matured synthetic leather is cooled to room temperature by the cooling wheel set, the release paper is peeled off, and finally the finished synthetic leather is wound up to obtain the double-layer functionalized antibacterial and hydrolysis resistant high elastic synthetic leather.

[0044] 3. Product Performance The performance of the synthetic leather samples obtained in this embodiment was tested, and the results are as follows: Feel and elasticity: The product has a soft feel and excellent bouncy elasticity.

[0045] Antibacterial properties: According to GB / T31402-2015 standard, the antibacterial rate against Staphylococcus aureus and Escherichia coli is greater than 99%.

[0046] Hydrolysis resistance: After being tested for 336 hours (14 days) at a temperature of 70℃ and a relative humidity of 95%, the surface showed no hydrolytic cracking, discoloration or bubbles, and the strength retention rate was above 85%.

[0047] Physical and mechanical properties: The tensile strength reaches 12MPa, and the air permeability is good.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A double-layer functionalized antibacterial, hydrolysis-resistant, high-elasticity synthetic leather, characterized in that, It includes a highly elastic wet-process base layer and a foaming layer and a dry-process surface layer sequentially stacked on the highly elastic wet-process base layer; The high-elasticity wet-laid base layer is formed by a high-elasticity base fabric and a foaming slurry that permeates and solidifies therein; The foaming slurry comprises the following components in parts by weight: 57 parts of hydrolysis-resistant soft wet-process resin, 34 parts of solvent, 12 parts of ultrafine calcium carbonate, 14 parts of pulp powder, 8 parts of low-modulus ultra-soft resin, 0.5 parts of antibacterial agent, 0.6 parts of water-based pigment, 0.9 parts of softener, and 0.8 parts of polyester-modified silicone ammonia oil. The foamed layer is formed by foaming a slurry containing a foaming resin and an isocyanate curing agent; The dry surface layer is formed from a slurry containing water-based resin and color flakes.

2. The double-layer functionalized antibacterial and hydrolysis-resistant high-elasticity synthetic leather according to claim 1, characterized in that, The high-elasticity base fabric is an ultra-thin antibacterial base fabric made of a blend of polyester fiber and castor fiber, with a thickness of 0.45mm.

3. The double-layer functionalized antibacterial and hydrolysis-resistant high-elasticity synthetic leather according to claim 1, characterized in that, The viscosity of the foaming slurry is 9000-10000 cps.

4. The double-layer functionalized antibacterial and hydrolysis-resistant high-elasticity synthetic leather according to claim 1, characterized in that, In the foaming layer slurry, the amount of isocyanate curing agent added is 1-2% of the weight of the foaming resin.

5. The double-layer functionalized antibacterial and hydrolysis-resistant high-elasticity synthetic leather according to claim 1, characterized in that, In the dry surface slurry, the amount of color flakes added is 3-8% of the weight of the water-based resin.

6. A method for preparing a double-layer functionalized antibacterial and hydrolysis-resistant high-elasticity synthetic leather as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Preparation of high elasticity base fabric: Provide a high elasticity base fabric made of polyester fiber and castor fiber blend; (2) Preparation and vacuum degassing of foamed slurry: The hydrolysis-resistant soft wet-process resin, solvent, ultrafine calcium carbonate, pulp powder, low modulus ultrasoft resin, antibacterial agent, water-based pigment, softener, and polyester modified silicone ammonia oil are mixed and stirred according to the formula, and vacuum degassing is performed to obtain foamed slurry. (3) Preparation of wet base fabric: After cleaning and ironing the high elasticity base fabric obtained in step (1), the foaming slurry obtained in step (2) is coated, and then it is coagulated in the coagulation liquid. After washing, ironing, drying and cooling, it is rolled up to obtain high elasticity wet base fabric. (4) Preparation of dry surface coating slurry: The water-based resin and color flakes are mixed, stirred and dispersed to obtain the dry surface coating slurry; (5) Preparation of foamed layer slurry: Add heavy filler to foaming resin and stir, and add isocyanate curing agent during stirring. After homogenization, foamed layer slurry is obtained. (6) Dry lamination and curing: The dry surface layer slurry obtained in step (4) is scraped onto the release paper and dried. Then the foam layer slurry obtained in step (5) is scraped onto the release paper and dried initially. Then it is laminated with the high elasticity wet base obtained in step (3). After curing and cooling, it is rolled up to obtain the synthetic leather.

7. The method according to claim 6, characterized in that, In step (2), the vacuum degassing time is 80 minutes.

8. The method according to claim 6, characterized in that, In step (3), the coagulation liquid is a solution with a mass fraction of 15%; after the coagulation process, 12 rounds of ironing and width fixing are performed in sequence.

9. The method according to claim 6, characterized in that, In step (6), the initial drying temperature after applying the foaming layer slurry is 70-85℃; the curing conditions after bonding are baking at 130℃ for 4-5 minutes.

10. The method according to claim 6, characterized in that, In step (6), after the foaming layer slurry is scraped and preliminarily dried, it is further cured at 150°C for 3 minutes before being bonded to the high-elasticity wet-process base.

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