Carbon dioxide-based polyurethane superfine fiber synthetic leather and preparation method thereof

Abstract

The invention relates to the technical field of superfine fiber synthetic leather, in particular to carbon-dioxide-based polyurethane superfine fiber synthetic leather and a preparation method thereof.The carbon-dioxide-based polyurethane superfine fiber synthetic leather comprises a base cloth layer, an interface connecting layer, a functional main body layer, a surface layer, a nanofiber reinforcing layer and a heat insulation layer, and the base cloth layer is connected with one face of the functional main body layer through the interface connecting layer; one side of the functional main body layer is connected with the base cloth layer, the other side of the functional main body layer is connected with the surface layer, the nanofiber reinforcement layer is located between the base cloth layer and the functional main body layer, and the heat insulation layer is located between the functional main body layer and the surface layer. The problem that existing carbon dioxide-based polyurethane superfine fiber synthetic leather is poor in practicability is solved.

Description

Technical Field

[0001] This invention relates to the field of microfiber synthetic leather technology, specifically to a carbon dioxide-based polyurethane microfiber synthetic leather and its preparation method. Background Technology

[0002] As is well known, carbon dioxide-based polyurethane microfiber synthetic leather is a type of synthetic leather made from polyurethane (PU) material prepared with carbon dioxide (CO2) as a partial raw material, combined with microfiber substrate. It is an environmentally friendly material that reduces dependence on traditional petroleum-based raw materials by converting carbon dioxide into polymer raw materials, while possessing excellent physical properties and a simulated leather texture.

[0003] Existing carbon dioxide-based polyurethane microfiber synthetic leather suffers from insufficient environmental performance, difficult-to-degrade surface layer, and poor thermal insulation, limiting its practicality. Specifically, traditional interface bonding layers use solvent-based adhesives, resulting in high VOC emissions, and the surface layer often uses non-degradable polyurethane materials, easily causing white pollution after disposal. At the same time, existing products lack efficient thermal insulation structures, failing to meet temperature control requirements in scenarios such as automotive interiors and outdoor equipment. They also have high thermal conductivity, with thermal insulation performance more than 30% lower than ideal, making them unsuitable for use in complex environments. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a carbon dioxide-based polyurethane microfiber synthetic leather and its preparation method.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a carbon dioxide-based polyurethane microfiber synthetic leather and its preparation method, comprising a base fabric layer, an interface bonding layer, a functional body layer, an epidermis layer, a nanofiber reinforcing layer, and a heat insulation layer. The base fabric layer is connected to one side of the functional body layer through the interface bonding layer, and the other side of the functional body layer is connected to the epidermis layer. The nanofiber reinforcing layer is located between the base fabric layer and the functional body layer, and the heat insulation layer is located between the functional body layer and the epidermis layer.

[0008] Preferably, the base fabric layer is a nonwoven fabric made of polymer materials such as polyester (e.g., PET) or polyamide (PA) through needle punching or hydroentangling processes. The fiber diameter is generally between 0.1 and 10 micrometers. The base fabric layer provides the skeleton structure of synthetic leather, enhances mechanical properties (such as tensile strength and abrasion resistance), and gives it a porous structure and soft feel similar to genuine leather.

[0009] Preferably, the interface bonding layer uses soybean protein-modified CO2-based PU (grafting rate 15%) to replace the traditional adhesive layer. According to the test, the VOC emission is reduced by 70% compared with the traditional material. This modification forms a stable structure through chemical grafting and uses soybean protein molecules to inhibit the emission of volatile organic compounds. It has both environmental protection and interface bonding strength, and is suitable for scenarios with high air quality requirements, such as automotive interiors.

[0010] Preferably, the functional main body layer is made of CO2-based polyurethane elastomer (Shore hardness A50~80), prepared by wet or dry coating process, with the thickness controlled at 0.3~0.8mm. The elastic modulus of this layer is optimized by adjusting the ratio of polyol to isocyanate. The temperature (60~80℃ for wet process / 120~150℃ for dry process) and curing time are precisely controlled during the coating process to ensure structural density and uniform mechanical properties.

[0011] Preferably, the nanofiber reinforcing layer is made of polyimide nanofiber membrane (800nm ​​in diameter), which is prepared into a three-dimensional network structure by electrospinning. After the layer is combined with the matrix, the tensile strength is increased by 30% compared with the original structure, and the bending resistance exceeds 100,000 times. The interfacial bonding force is enhanced through interfiber hydrogen bonding, which effectively improves the fatigue resistance of synthetic leather.

[0012] Preferably, the heat insulation layer is made of a 20-50 μm thick SiO2 aerogel film (thermal conductivity <0.02 W / (m・K)), which is combined with the upper and lower functional layers to form a "sandwich" structure. This film inhibits heat conduction through a nanoporous network. According to the heat flow meter test, the heat insulation effect is improved by 40% compared with the traditional structure, and it is both lightweight (density <0.15 g / cm³) and flexible.

[0013] This invention further provides a method for preparing carbon dioxide-based polyurethane microfiber synthetic leather, characterized by comprising the following steps:

[0014] Step 1: Purify carbon dioxide and carry out ring-opening polymerization with epoxy compounds under the action of a catalyst to produce polyols containing carbonate groups. Mix the polyols with isocyanates (such as TDI, MDI) and chain extenders, and obtain polyurethane resins through stepwise polymerization reactions.

[0015] Step 2: Melt-spin polyester or polyamide chips to form composite fibers, which are then stretched and cooled to form a fiber web, and then processed into nonwoven fabric substrates through needle punching, hydroentangling and other processes.

[0016] Step 3: Set a polyimide nanofiber membrane (800nm ​​in diameter) on the surface of the base layer, then dissolve carbon dioxide-based polyurethane resin in solvents such as DMF (dimethylformamide) to make a slurry, then coat the slurry evenly on the base fabric layer, immerse it in water to allow the solvent to diffuse and precipitate, and the polyurethane to cure to form a porous sponge layer that is tightly bonded to the base fabric layer.

[0017] Step 4: Then, the epidermal layer is connected to the functional main body layer through an aerogel film to form a "sandwich" structure, which improves the heat insulation effect by 40%.

[0018] Step 5: Wash and dry the prepared structure, and then simulate the texture of genuine leather through processes such as printing, embossing, and spraying to complete the production.

[0019] (III) Beneficial Effects

[0020] Compared with the prior art, the present invention provides a carbon dioxide-based polyurethane microfiber synthetic leather and its preparation method, which has the following beneficial effects:

[0021] This carbon dioxide-based polyurethane microfiber synthetic leather and its preparation method are as follows: In terms of environmental friendliness, the interface bonding layer uses soybean protein-modified CO2-based PU, reducing VOC emissions by 70% and achieving a bio-based content of 45%, meeting Oeko-Tex® Standard 100 certification. Furthermore, using carbon dioxide as a raw material reduces dependence on petroleum and lowers carbon emissions. Regarding performance, the base fabric layer imparts a tensile strength of ≥15MPa, a soft feel similar to genuine leather, and breathability and moisture permeability. The nanofiber reinforcement layer increases tensile strength by 30% and withstands over 100,000 flex cycles. The SiO2 aerogel film in the heat insulation layer forms a "sandwich" structure, improving heat insulation by 40% while maintaining lightweight and flexible adaptability. The functional main layer ensures uniform mechanical properties through process control. The scientifically designed preparation method and the composite of each layer enhance overall performance, making it suitable for various applications such as automotive interiors, medical supplies, and outdoor equipment. It solves the problems of poor environmental friendliness and inadequate heat insulation in existing synthetic leathers, demonstrating strong practicality. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] A carbon dioxide-based polyurethane microfiber synthetic leather and its preparation method are disclosed, comprising a base fabric layer, an interface bonding layer, a functional host layer, an epidermal layer, a nanofiber reinforcing layer, and a heat insulation layer. The base fabric layer is connected to one side of the functional host layer through the interface bonding layer, and the other side of the functional host layer is connected to the epidermal layer. The nanofiber reinforcing layer is located between the base fabric layer and the functional host layer, and the heat insulation layer is located between the functional host layer and the epidermal layer.

[0024] In this embodiment, the base fabric layer is made of polymer materials such as polyester (PET) or polyamide (PA), and is made into a nonwoven fabric through needle punching and hydroentangling composite processes. The fiber diameter is precisely controlled within the range of 0.1~10 micrometers. A three-dimensional interwoven network structure forms a skeleton support system with a porosity of 60%~80%. This base fabric layer not only provides synthetic leather with a tensile strength of ≥15MPa and excellent abrasion resistance (Taber abrasion amount <10mg / 1000 times), but its biomimetic porous structure also gives the material a soft touch similar to genuine leather (hardness 15~25cN) and breathability and moisture permeability (water vapor transmission rate ≥5000g / (m²・24h)). After being impregnated and cured with polyurethane (CO2-based PU), a mechanical interlocking structure is formed between the base fabric layer and the coating, further improving the uniformity of the overall mechanical properties.

[0025] In this embodiment, the interface bonding layer uses soybean protein-modified CO2-based PU (grafting rate 15%) to replace the traditional solvent-based adhesive layer. Through a dynamic melt grafting process, soybean protein and CO2-based PU form a covalent network. According to ISO16000-9 standard testing, the VOC emission level is reduced from 2.8 mg / m² to 0.84 mg / m², a reduction of 70%. This modified system utilizes the physical encapsulation and chemical adsorption of soybean protein amino groups to inhibit the escape of small molecules. At the same time, the cohesive strength is enhanced through the nano-montmorillonite layered structure, and the interfacial peel strength is increased to 4.2 N / cm. Its bio-based content reaches 45%, meeting the Oeko-Tex® Standard 100 certification requirements. It is suitable for scenarios with stringent air quality and environmental protection requirements, such as automotive interiors and medical products.

[0026] In this embodiment, the functional main body layer is made of CO2-based polyurethane elastomer (Shore hardness A50~80), prepared by wet or dry coating process, with the thickness precisely controlled at 0.3~0.8mm. This layer achieves gradient optimization of elastic modulus (0.5~2MPa) by adjusting the molar ratio of CO2-based polyether polyol to isocyanate (such as MDI / TDI) (1.2~1.5:1). During wet coating, the coagulation bath temperature is controlled at 60~80℃ and the DMF moisture content is controlled at 20%~30%. During dry coating, the oven temperature is set at 120~150℃ and the curing time is set at 5~10min. By precisely controlling the process parameters, the coating structure is ensured to be dense (porosity 30%~50%), and the uniformity deviation of mechanical properties such as tensile strength (≥10MPa) and elongation at break (300%~500%) is ≤5%.

[0027] In this embodiment, the nanofiber reinforcing layer is made of polyimide (PI) nanofiber membrane, which is prepared into a three-dimensional network structure with a diameter of 800 nm by electrospinning. The membrane has a porosity of 85%~90% and a specific surface area of ​​>100m² / g. When composited with the matrix, the interfacial compatibility is enhanced by plasma surface modification (introducing hydroxyl groups). After testing, the tensile strength of the composite material increased from 15MPa to 19.5MPa (an increase of 30%), the bending resistance exceeded 100,000 cycles (ASTM D2176 standard), and the elongation at break retained ≥85%. Its reinforcement mechanism comes from the mechanical interlocking structure formed between the hydrogen bond network (bond energy of about 20kJ / mol) between the PI nanofibers and the matrix, which effectively inhibits crack propagation and significantly improves the fatigue resistance and weather resistance of synthetic leather.

[0028] In this embodiment, the thermal insulation layer is made of SiO2 aerogel film with a thickness of 20~50μm (thermal conductivity <0.02W / (m・K)), which is combined with the upper and lower functional layers to form a "sandwich" structure. The film suppresses the thermal motion of air molecules through a nanoscale porous network (pore size 2~50nm). According to the ASTM C177 heat flow meter test, the thermal resistance is improved by 40% compared with the traditional structure, and the heat transfer coefficient is reduced to below 0.12W / (m²・K). Its density is <0.15g / cm³, and its flexibility reaches a bending radius ≤5mm, which can be adapted to curved substrates. The surface of the film is modified with methyltrimethoxysilane for hydrophobicity (contact angle >120°), which has both water vapor penetration resistance and weather resistance, and is suitable for thermal insulation scenarios such as outdoor equipment and automotive interiors.

[0029] This invention further provides a method for preparing carbon dioxide-based polyurethane microfiber synthetic leather, characterized by comprising the following steps:

[0030] Step 1: Purify carbon dioxide and carry out ring-opening polymerization with epoxy compounds under the action of a catalyst to produce polyols containing carbonate groups. Mix the polyols with isocyanates (such as TDI, MDI) and chain extenders, and obtain polyurethane resins through stepwise polymerization reactions.

[0031] Step 2: Melt-spin polyester or polyamide chips to form composite fibers, which are then stretched and cooled to form a fiber web. The web is then processed through needle punching, hydroentangling, and other processes to produce a nonwoven fabric substrate.

[0032] Step 3: Set a polyimide nanofiber membrane (800nm ​​in diameter) on the surface of the base layer, then dissolve carbon dioxide-based polyurethane resin in solvents such as DMF (dimethylformamide) to make a slurry, then coat the slurry evenly on the base fabric layer, immerse it in water to allow the solvent to diffuse and precipitate, and the polyurethane to cure to form a porous sponge layer that is tightly bonded to the base fabric layer.

[0033] Step 4: Then, the epidermal layer is connected to the functional main body layer through an aerogel film to form a "sandwich" structure, which improves the heat insulation effect by 40%.

[0034] Step 5: Wash and dry the prepared structure, and then simulate the texture of genuine leather through processes such as printing, embossing, and spraying to complete the production.

[0035] In summary, this invention achieves a synergistic improvement in environmental performance, mechanical strength, and thermal insulation function through multi-layer structural design and material innovation. The synthetic leather includes a base fabric layer, an interface bonding layer, a functional main body layer, an epidermis layer, a nanofiber reinforcement layer, and a thermal insulation layer. The base fabric layer is made of polyester or polyamide through needle punching and hydroentangling to form a non-woven fabric, creating a high-porosity skeleton that gives the material high strength, wear resistance, and a leather-like feel and breathability. The interface bonding layer uses soybean protein-modified CO2-based PU to replace traditional adhesives, reducing VOC emissions by 70% and achieving a bio-based content of 45%, resulting in outstanding environmental performance and a strong interface bond. The functional main body layer achieves precise optimization of mechanical properties and a dense and uniform structure by controlling the ratio of CO2-based polyurethane elastomer and coating process. The polyimide nanofiber membrane of the nanofiber reinforcement layer increases tensile strength by 30%, withstands more than 100,000 flexes, and improves fatigue resistance. The SiO2 aerogel film of the thermal insulation layer forms a "sandwich" structure, increasing thermal resistance by 40% and combining lightweight, flexibility, and weather resistance.

[0036] The preparation method includes steps such as carbon dioxide-based polyurethane resin synthesis, base fabric preparation, multilayer composite and post-treatment. The process is scientific and reasonable. This synthetic leather solves the problems of poor environmental performance and poor heat insulation effect of existing products. It is suitable for multiple scenarios such as automotive interiors, medical care, and outdoor equipment. It is highly practical and provides a new solution for the green and functional development of the synthetic leather industry.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A carbon dioxide-based polyurethane microfiber synthetic leather and a preparation method thereof, comprising a base cloth layer, an interface connecting layer, a functional main body layer, a skin layer, a nanofiber reinforcing layer and a thermal insulation layer, characterized in that: The base cloth layer is connected with the functional body layer through the interface connecting layer, the other side of the functional body layer is connected with the skin layer, the nanofiber reinforced layer is located between the base cloth layer and the functional body layer, and the thermal insulation layer is located between the functional body layer and the skin layer.

2. The carbon dioxide-based polyurethane microfiber synthetic leather according to claim 1, characterized by: The base cloth layer is a non-woven fabric made of polyester (such as PET) or polyamide (PA) and the like high molecular material through needle punching and water jet process, the fiber diameter is generally between 0.1-10 microns, the base cloth layer provides the framework structure of synthetic leather, enhances the mechanical properties (such as tensile strength and wear resistance), and gives the porous structure similar to the dermis and soft hand feeling.

3. The carbon dioxide-based polyurethane microfiber synthetic leather according to claim 2, characterized by: The interface connecting layer uses soy protein modified CO2-based PU (grafting rate 15%) to replace the traditional adhesive layer, and the VOC emission amount is reduced by 70% compared with the traditional material, the modification forms a stable structure through chemical grafting, and the volatile organic matter is inhibited from escaping by using soy protein molecules, which has environmental protection and interface bonding strength, and is suitable for high air quality requirements such as automotive interiors.

4. The carbon dioxide-based polyurethane microfiber synthetic leather according to claim 3, characterized by: The functional body layer uses CO2-based polyurethane elastomer (Shore hardness A 50-80), which is prepared by wet or dry coating process, and the thickness is controlled within 0.3-0.8mm, the elastic modulus is optimized by adjusting the ratio of polyol and isocyanate, and the temperature (wet 60-80℃ / dry 120-150℃) and curing time are accurately controlled during coating process to ensure the structural density and mechanical property uniformity.

5. The carbon dioxide-based polyurethane microfiber synthetic leather according to claim 4, characterized in that: The nanofiber reinforced layer selects polyimide nanofiber membrane (diameter 800nm) prepared by electrospinning process to form a three-dimensional network structure, the tensile strength of the layer after compounding with the base is increased by 30% compared with the original structure, the bending resistance is more than 100,000 times, the interface bonding force is enhanced by hydrogen bond between fibers, and the fatigue resistance of synthetic leather is effectively improved.

6. The carbon dioxide-based polyurethane microfiber synthetic leather according to claim 5, characterized by: The thermal insulation layer selects 20-50μm thick SiO2 aerogel film (thermal conductivity <0.02W / (m·K)), which is combined with the upper and lower functional layers to form a "sandwich" structure, the film inhibits heat conduction through nano-porous network, and the thermal insulation effect is improved by 40% compared with the traditional structure, and it has light weight (density <0.15g / cm³) and flexible adaptability.

7. The method of claim 6, wherein the method is characterized by: The method comprises the following steps: Step one: carbon dioxide is purified, and ring-opening polymerization is carried out with epoxy compounds under the action of a catalyst to produce a polyol containing a carbonate group, the polyol is mixed with isocyanate (such as TDI, MDI) and a chain extender, and polyurethane resin is prepared by step-by-step polymerization reaction; Step two: polyester or polyamide chips are melt spun to form composite fibers, a fiber web is formed after drawing and cooling, and a non-woven fabric base material is prepared by needle punching, water jetting and the like process; Step three: polyimide nanofiber membrane (diameter 800nm) is arranged on the surface of the base layer, carbon dioxide-based polyurethane resin is dissolved in DMF (dimethylformamide) and the like solvent to prepare slurry, the slurry is uniformly coated on the base cloth layer, the solvent is diffused and precipitated in water, and the polyurethane is solidified to form a porous sponge layer, which is tightly combined with the base cloth layer; Step four: Then the epidermis layer is connected with the functional main body layer through aerogel film to form a "sandwich" structure, and the heat insulation effect is improved by 40%; Step five: The prepared structure is washed and dried, and then a real leather texture is simulated through printing, embossing, spraying and other processes to complete the preparation.