Super-soft breathable bionic leather and preparation method thereof

Abstract

The invention relates to super-soft breathable bionic leather and a preparation method thereof, and belongs to the technical field of artificial leather composite materials. According to the invention, the microporous structure of the flexible resin layer is combined with the three-dimensional network structure of the elastic fiber layer, so that an efficient air-permeable and moisture-permeable passage is constructed, and the contradiction between water resistance and air permeability is solved. The unique superfine elastic fiber layer simulates softness and elasticity of genuine leather, soft touch and buffering protection like natural skin are provided, and the fabric is particularly suitable for children with sensitive skin and female clothes pursuing comfort. A four-layer functional structure corresponding to epidermis, dermis and subcutaneous tissues of human skin is clearly proposed and realized for the first time, all the layers have a synergistic effect, and the comprehensive performance is excellent.

Description

Technical Field

[0001] This invention relates to an ultra-soft and breathable biomimetic leather and its preparation method, belonging to the field of artificial leather composite materials technology. Background Technology

[0002] Currently, artificial leather (synthetic leather) is an important textile material widely used in clothing, bags, furniture, and other fields. Traditional artificial leather focuses on appearance simulation and durability, but it still lags significantly behind natural leather in terms of wearing comfort, especially breathability, moisture permeability, and soft touch. Some products use dense coatings or films to achieve waterproofing, resulting in poor breathability and a stuffy feeling; while the pursuit of softness often sacrifices the material's mechanical strength and abrasion resistance.

[0003] Human skin is the most perfect flexible protective system in nature. Its multi-layered structure (epidermis, dermis, and subcutaneous tissue) works together to achieve multiple functions such as protection, sensing, breathability, and temperature regulation. Therefore, drawing on the structural principles of human skin, developing a highly breathable biomimetic leather with multiple excellent properties has become an important research direction in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this invention is to provide an ultra-soft and breathable bionic leather and its preparation method.

[0005] The present invention provides an ultra-soft and breathable bionic leather, comprising, from the outside to the inside:

[0006] The protective layer, formed by spraying a waterproofing agent, serves to provide waterproofing and abrasion resistance;

[0007] The flexible resin layer, composed of a microporous aqueous polyurethane resin, is used for moisture permeability and air permeability.

[0008] The elastic fiber layer, composed of an ultra-fine three-dimensional elastic fiber network and water-based polyurethane resin filling its gaps, is used to provide elasticity, softness and cushioning.

[0009] The base fabric layer is used to provide mechanical support and determine the material style.

[0010] Furthermore, the waterproofing agent in the protective layer is either a fluorinated waterproofing agent or an organosilicon-modified polyurethane, and the static water contact angle of the protective layer is greater than 150°.

[0011] Furthermore, the waterborne polyurethane in the flexible resin layer is either a polyurethane with introduced hydrophilic segments of polyethylene glycol or a waterborne polyurethane of KR-8502.

[0012] Furthermore, the ultrafine three-dimensional elastic fiber network in the elastic fiber layer is a membrane-like elastic nonwoven fabric with a basis weight of 60-90 g / m2 and a thickness of 0.25-0.35 mm, formed by polyurethane fibers with a diameter of 100-200 nm laid in a loose and disordered manner, and having a microporous structure.

[0013] Furthermore, the pore size of the microporous structure is 5–50 μm.

[0014] Furthermore, the waterborne polyurethane resin filled in the elastic fiber network is a high-resilience waterborne polyurethane resin, with a tensile deformation greater than 40% after curing.

[0015] Furthermore, the base fabric layer is any type of nonwoven fabric, woven fabric, or knitted fabric.

[0016] A method for preparing ultra-soft and breathable biomimetic leather, the specific preparation steps are as follows:

[0017] (1) Preparation of base fabric layer: Provide a base fabric layer;

[0018] (2) Preparation of elastic fiber layer: Polyurethane is spun into ultrafine fibers, and the ultrafine fibers are laid in a loose and disordered manner to form a membrane elastic nonwoven fabric; the obtained membrane elastic nonwoven fabric is then immersed in water-based polyurethane resin slurry by a two-dip and two-bundle method, and after drying, an elastic fiber layer with a continuous porous structure is formed.

[0019] (3) Preparation of flexible resin layer: water-based polyurethane slurry is foamed by a foaming machine to form foamed polyurethane slurry, which is then coated onto release paper, and the above-mentioned elastic fiber layer is laid on top, dried and cured to form a flexible resin layer with moisture-permeable micropores on the surface of the elastic fiber layer.

[0020] (4) Composite molding: On the back of the elastic fiber layer after the flexible resin layer is coated, it is composited with the base fabric layer by adhesive dots.

[0021] (5) Finishing to form a protective layer: Finally, a waterproofing agent is applied to the surface of the flexible resin layer by spraying and then baked to form a protective layer with low surface energy, thus obtaining an ultra-soft and breathable bionic skin.

[0022] By means of the above-described solution, the present invention has at least the following advantages:

[0023] 1. Bionic structural design: This invention is the first to clearly propose and realize a four-layer functional structure corresponding to the epidermis, dermis and subcutaneous tissue of human skin. Each layer works synergistically and has excellent comprehensive performance.

[0024] 2. Superior comfort: This invention combines the "microporous structure of the flexible resin layer" with the "three-dimensional network structure of the elastic fiber layer" to construct an efficient breathable and moisture-wicking pathway, thus resolving the contradiction between waterproofing and breathability.

[0025] 3. Excellent tactile feel: The unique ultra-fine elastic fiber layer of this invention simulates the softness and elasticity of genuine leather, providing a soft touch and cushioning protection like natural skin, making it especially suitable for children with sensitive skin and women's clothing that prioritizes comfort.

[0026] 4. Flexible application: The replaceable base fabric design of this invention allows for the rapid development of various product series with different styles, thicknesses, and uses by changing the base fabric, resulting in strong market adaptability.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show a certain embodiment of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the ultra-soft and breathable bionic leather of the present invention. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] (1) Preparation of base fabric layer: The base fabric layer is any type of nonwoven fabric, woven fabric or knitted fabric.

[0032] A microfiber nylon warp-knitted fabric with a thickness of 0.5 mm and a single filament fineness of 0.1 to 0.5 dpf can be selected as the base fabric layer;

[0033] The base fabric layer can also be a microfiber nonwoven fabric or a high-count, high-density knitted warp-knitted fabric that has undergone napping and brushing treatment.

[0034] This layer corresponds to the subcutaneous tissue of the human body. It provides mechanical support, dimensional stability, and drape to the entire bionic leather, and ultimately determines the appearance and feel of the bionic leather by selecting different types and styles of base fabric.

[0035] (2) Preparation of elastic fiber layer: Polyurethane is spun into ultrafine fibers with a fiber fineness of 100-200 nm, and the ultrafine fibers are laid in a loose and disordered web to form a microporous structure with a basis weight of 60-90 g / m. 2 A membrane-like elastic nonwoven fabric with a thickness of 0.25–0.35 mm is obtained; the microporous structure has a pore size of 5–50 μm; the obtained membrane-like elastic nonwoven fabric is then immersed in an aqueous polyurethane resin slurry using a two-dip, two-bundle method, and dried at 120 degrees Celsius to form an elastic fiber layer with a continuous porous structure.

[0036] The waterborne polyurethane resin is KR-8502 waterborne polyurethane. KR-8502 is an anionic aliphatic polyurethane dispersion, soft and elastic, with a milky white appearance, a solid content of 48-50%, a pH value of 6.0-9.0, a viscosity of 10-6000 mPa·s, and a density of 1.02-1.09 g / cm³. 3 It has a tensile strength of 24 MPa, an elongation of 880%, and a 100% modulus of 1.0 MPa.

[0037] This layer corresponds to the dermis in the human body and is the core functional layer. The hollow parts of the fiber network in this layer are filled and bonded with soft polyurethane resin, forming a continuous and elastic "sea-island" structure ("islands" are fibers, and "seas" are PU). This structure not only provides extremely high softness and elastic recovery, but its numerous pores also constitute the main air-permeable channels and buffer spaces, effectively absorbing and dispersing external stress.

[0038] (3) Preparation of flexible resin layer: The water-based polyurethane slurry is foamed using a foaming machine to form a foamed polyurethane slurry, which is then coated onto the release paper with a dry weight of approximately 20 g / m². 2 Then, the above-mentioned elastic fiber layer is laid on top and dried and cured at 120°C to form a flexible resin layer with interconnected moisture-permeable micropores with a pore size of 10-50nm on the surface of the elastic fiber layer.

[0039] This layer corresponds to the transition layer between the epidermis and dermis in the human body. It is composed of a microporous aqueous polyurethane resin. The aqueous polyurethane is foamed to form interconnected micropore channels. These channels allow water vapor molecules (sweat) to pass through but block liquid water, thus achieving moisture permeability and breathability. This layer also provides initial softness and abrasion resistance.

[0040] (4) Composite molding: On the back of the elastic fiber layer after the flexible resin layer is coated, it is then bonded to the base fabric layer by adhesive dots. The amount of adhesive applied is 35-40 g / m² (dry weight). 2 .

[0041] (5) Finishing to form a protective layer: Finally, a waterproofing agent is applied to the surface of the flexible resin layer by spraying, with a spraying amount of 5g / m². 2 Baking and curing at 150℃ forms a protective layer with low surface energy, resulting in ultra-soft and breathable bionic leather.

[0042] The waterproofing agent is either a fluorinated waterproofing agent or an organosilicon-modified polyurethane. It imparts permanent hydrophobicity and excellent abrasion resistance to the biomimetic skin, with a static water contact angle greater than 150°, achieving both waterproofing and stain resistance.

[0043] This layer corresponds to the epidermis of the human body. It is composed of a fluoropolymer or silicone-modified polyurethane coating, giving the biomimetic skin permanent hydrophobicity and excellent abrasion resistance. Its static water contact angle is greater than 150°, achieving waterproof and stain-resistant functions.

[0044] Example 1

[0045] (1) Preparation of base fabric layer: 0.5 mm thick and 0.5 dpf fineness fiber nylon warp knitted fabric is selected as base fabric layer.

[0046] (2) Preparation of elastic fiber layer: Polyurethane is spun into ultrafine fibers with a fiber fineness of 100 nm, and the ultrafine fibers are laid in a loose and disordered web to form a microporous structure with a basis weight of 60 g / m. 2 A 0.25 mm thick membrane-like elastic nonwoven fabric is obtained; the microporous structure has a pore size of 5 μm; the obtained membrane-like elastic nonwoven fabric is then immersed in KR-8502 waterborne polyurethane resin slurry through a two-dip two-bundle method, and after drying at 120 degrees, an elastic fiber layer with a continuous porous structure is formed.

[0047] (3) Preparation of flexible resin layer: KR-8502 waterborne polyurethane slurry is foamed using a foaming machine to form foamed polyurethane slurry, which is then coated onto the release paper with a dry weight of approximately 20 g / m². 2 Then, the above-mentioned elastic fiber layer is laid on top and dried and cured at 120°C to form a flexible resin layer with interconnected moisture-permeable micropores with a pore size of 10-50nm on the surface of the elastic fiber layer.

[0048] (4) Composite molding: On the back of the elastic fiber layer after the flexible resin layer is coated, it is then laminated with the base fabric layer by adhesive dots. The amount of adhesive applied is 15g / m² (dry weight). 2 .

[0049] (5) Finishing to form a protective layer: Finally, a layer of fluorinated waterproofing agent is applied to the surface of the flexible resin layer by spraying, with a spraying amount of 5g / m². 2 Baking and curing at 150℃ forms a protective layer with low surface energy, resulting in ultra-soft and breathable bionic leather.

[0050] Example 2

[0051] (1) Preparation of base fabric layer: 0.5 mm thick, 40 gsm polyester double-sided knitted fabric is selected as base fabric layer.

[0052] (2) Preparation of elastic fiber layer: Polyurethane is spun into ultrafine fibers with a fiber fineness of 200 nm, and the ultrafine fibers are laid in a loose and disordered web to form a microporous structure with a basis weight of 90 g / m. 2 An elastic fiber layer with a porous structure, 0.35 mm thick and 50 μm in diameter, was prepared.

[0053] (3) Preparation of flexible resin layer: KR-8502 waterborne polyurethane slurry is foamed using a foaming machine to form foamed polyurethane slurry, which is then coated onto the release paper with a dry weight of approximately 20 g / m². 2 Then, the above-mentioned elastic fiber layer is laid on top and dried and cured at 120°C to form a flexible resin layer with interconnected moisture-permeable micropores with a pore size of 50nm on the surface of the elastic fiber layer.

[0054] (4) Composite molding: On the back of the elastic fiber layer after the flexible resin layer is coated, it is then laminated with the base fabric layer by adhesive dots. The amount of adhesive applied is 15g / m² (dry weight). 2 .

[0055] (5) Post-treatment to form a protective layer: Finally, a layer of silicone-modified polyurethane is applied to the surface of the flexible resin layer by spraying, with a spraying amount of 5 g / m². 2 Baking and curing at 130℃ forms a protective layer with low surface energy, resulting in ultra-soft and breathable bionic leather.

[0056] Compare with Example 1

[0057] The preparation method of Comparative Example 1 adopts the traditional artificial leather preparation process, in which water-based polyurethane slurry is coated onto release paper, with a dry weight of approximately 20 g / m². 2 The material is dried and cured at 120℃; then a layer of adhesive is applied, followed by 250gsm needle-punched nonwoven fabric. After drying, the release paper is peeled off to produce traditional artificial leather.

[0058] Performance testing: Performance tests were performed on Examples 1-2 and Comparative Example 1 of the present invention, respectively. The test results are shown in Table 1.

[0059] Detection methods

[0060] (1) Air permeability: Refer to GB / T 5453-1997 (test area: 20cm2, test pressure: 100Pa);

[0061] (2) Moisture permeability: Refer to GB / T 12704.2-2009 condition a (positive cup method, test chamber temperature: 38℃, relative humidity: 50%, wind speed: 0.3~0.5m / s, reverse side facing water);

[0062] (3) Bending performance: Refer to GB / T 18318.1-2009 inclined plane method;

[0063] (4) Feel: Based on subjective evaluation and instrument testing, it is significantly better than conventional PU synthetic leather and reaches the super soft level.

[0064] Table 1 Performance Test Results

[0065]

[0066] Results analysis:

[0067] The test data shows that the bionic leather in Examples 1 and 2 has good breathability and moisture permeability, indicating that the bionic leather has excellent comfort; the bending length is only 1.7cm, indicating that the bionic leather is softer, proving that the bionic leather prepared by imitating the four-layer bionic structure of "base fabric layer + elastic fiber layer + flexible resin layer + protective layer" of human skin has excellent performance.

[0068] The biomimetic leather exhibits excellent breathability and moisture permeability, with an air permeability exceeding 50mm / s and a moisture permeability of 3500g / m². 2 The core reason for its superior performance of over 24 hours is that the elastic fiber layer has 5-50μm micropores and the flexible resin layer has 10-50nm breathable micropores, forming a breathable pathway with "coarse and fine pores working together". The large pore size of the elastic fiber layer ensures rapid air circulation, while the nanoscale micropores of the flexible resin layer block liquid water while allowing water vapor to permeate efficiently, thus completely resolving the contradiction between "waterproof and breathable".

[0069] With ideal waterproof performance, the biomimetic skin surface is sprayed with a waterproof agent, and the static water contact angle is >150°. The nanopores of the flexible resin layer work together to directly block the infiltration of external liquid water. The nanopores of the flexible resin layer further intercept a small amount of water molecules that penetrate, providing a double guarantee for waterproof effect.

[0070] The material has an ultra-soft feel, with a level 5 feel achieved through the "sea-island structure" of the elastic fiber layer, which is a network of ultra-fine fibers filled with PU resin. The 100-200nm ultra-fine fibers provide a softness similar to natural leather. The high elasticity of PU resin, with an elongation rate of up to 880%, gives the material cushioning. Combined with the drape of the base fabric layer, this ultimately achieves a "sensitive skin-friendly" feel.

[0071] The test results for the control group showed that:

[0072] In contrast to Example 1, which uses needle-punched nonwoven fabric as the base layer and lacks an elastic support layer in the middle, the fabric feels too stiff and lacks softness and drape. Its air permeability and moisture permeability are only 0.3 and 50 respectively, indicating that the polyurethane film layer lacks a microporous structure. Combined with the intermediate adhesive, this results in very poor air and moisture permeability. This is a common problem in domestically produced artificial leather.

[0073] In summary, the four-layer structure of the biomimetic skin material of this invention is indispensable, and biomimetic design is the key to its performance.

[0074] The four-layer biomimetic structure of this invention is not a simple superposition, but rather each layer has complementary functions and synergistic effects:

[0075] The base fabric layer provides support, the elastic fiber layer is breathable and has a good feel, the flexible resin layer is breathable and assists in waterproofing, and the protective layer is waterproof, together forming a performance closed loop of "breathable and breathable - waterproof - soft".

[0076] The absence of any layer will lead to a decrease in overall performance, further verifying the innovation and necessity of the "bionic structural design" of this invention, and also providing performance support for its application in scenarios such as children's clothing and sensitive skin clothing.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit 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 technical principles 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 super-soft and breathable bionic leather, characterized in that: From the outside in, the following are included: The protective layer, formed by spraying a waterproofing agent, serves to provide waterproofing and abrasion resistance; The flexible resin layer, composed of a microporous aqueous polyurethane resin, is used for moisture permeability and air permeability. The elastic fiber layer, composed of an ultra-fine three-dimensional elastic fiber network and water-based polyurethane resin filling its gaps, is used to provide elasticity, softness and cushioning. The base fabric layer is used to provide mechanical support and determine the material style.

2. The ultra-soft and breathable bionic leather according to claim 1, characterized in that: The waterproofing agent in the protective layer is either a fluorinated waterproofing agent or an organosilicon-modified polyurethane, and the static water contact angle of the protective layer is greater than 150°.

3. The ultra-soft and breathable bionic leather according to claim 1, characterized in that: The waterborne polyurethane in the flexible resin layer is either a polyurethane with introduced hydrophilic segments of polyethylene glycol or KR-8502 waterborne polyurethane.

4. The ultra-soft and breathable bionic leather according to claim 1, characterized in that: The ultrafine three-dimensional elastic fiber network in the elastic fiber layer consists of polyurethane fibers with a diameter of 100–200 nm, arranged in a loose and disordered manner to form a microporous structure with a basis weight of 60–90 g / m². 2 A film-like elastic nonwoven fabric with a thickness of 0.25 to 0.35 mm.

5. The ultra-soft and breathable bionic leather according to claim 4, characterized in that: The microporous structure has a pore size of 5–50 μm.

6. The ultra-soft and breathable bionic leather according to claim 1, characterized in that: The waterborne polyurethane resin filled in the elastic fiber network is a high-resilience waterborne polyurethane resin, and its tensile deformation is greater than 40% after curing.

7. The ultra-soft and breathable bionic leather according to claim 1, characterized in that: The base fabric layer can be any type of nonwoven fabric, woven fabric, or knitted fabric.

8. A method for preparing an ultra-soft and breathable biomimetic leather as described in any one of claims 1-7, characterized in that... The specific preparation steps are as follows: (1) Preparation of base fabric layer: Provide a base fabric layer; (2) Preparation of elastic fiber layer: Polyurethane is spun into ultrafine fibers, and the ultrafine fibers are laid in a loose and disordered manner to form a membrane elastic nonwoven fabric; the obtained membrane elastic nonwoven fabric is then immersed in water-based polyurethane resin slurry by a two-dip and two-bundle method, and after drying, an elastic fiber layer with a continuous porous structure is formed. (3) Preparation of flexible resin layer: water-based polyurethane slurry is foamed by a foaming machine to form foamed polyurethane slurry, which is then coated onto release paper, and the above-mentioned elastic fiber layer is laid on top, dried and cured to form a flexible resin layer with moisture-permeable micropores on the surface of the elastic fiber layer. (4) Composite molding: On the back of the elastic fiber layer after the flexible resin layer is coated, it is composited with the base fabric layer by adhesive dots. (5) Finishing to form a protective layer: Finally, a waterproofing agent is applied to the surface of the flexible resin layer by spraying and then baked to form a protective layer with low surface energy, thus obtaining an ultra-soft and breathable bionic skin.

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