High-strength degradable leather based on mycelium fiber and preparation method thereof

Abstract

This invention relates to a high-strength biodegradable leather based on mycelial fibers and its preparation method, belonging to the field of bio-based materials technology. The preparation method includes the following steps: High-strength polylactic acid filaments are used as the core yarn, and natural or regenerated cellulose short fibers are used as the covering yarn. This is spun into a core-spun yarn with a cellulose short fiber surface layer and a polylactic acid filament core layer, which is then woven to obtain a mesh fabric. This fabric is then layered with a substrate for mycelial growth and subjected to solid-state fermentation. After cultivation, the substrate undergoes hot pressing, modification, cross-linking, plasticizing, polyurethane impregnation, and drying to obtain mycelial leather substrate. Finally, the substrate undergoes brushing, lamination, vacuum texturing, or embossing processes to produce a reinforced biodegradable leather product with mycelial fibers as the main body. The leather obtained by this invention possesses excellent water vapor permeability, bending resistance, abrasion resistance, mechanical properties, and biodegradability. This product has promising applications in the fashion industry, including bags, home furnishings, and clothing decoration.

Description

Technical Field

[0001] This invention relates to a high-strength biodegradable leather based on mycelial fibers and its preparation method, belonging to the field of bio-based materials technology. Background Technology

[0002] Natural leather products, due to their excellent elasticity, abrasion resistance, water permeability, and mechanical properties, are still widely used in people's daily lives. However, the development of natural leather is limited by issues such as scarce animal resources and high product prices. Meanwhile, with the development of science and technology, the quality of synthetic leather products has made a qualitative leap. Among them, microfiber synthetic leather products have seen rapid development in quality and variety, and their performance is comparable to, and in some cases even surpasses, that of natural leather. Currently, microfiber synthetic leather is gradually replacing natural leather and is widely used in home sofas, car seats, clothing, and footwear. However, the main components used in its production—synthetic fibers and polyurethane—are derived from petroleum products, have long degradation cycles after disposal, and the production process uses large amounts of organic solvents, causing significant environmental impact. Against this backdrop, the development of environmentally friendly, biodegradable leather products is of great importance.

[0003] Plant fibers are abundant natural fiber materials and ideal substitutes for petroleum-based synthetic fibers in synthetic leather. Patent CN115418866A reports a method for preparing biodegradable artificial leather using plant bast fibers, such as pineapple leaf fiber and coconut shell fiber, through a bottom-up layering process. Patent CN111455681A reports a method for preparing biodegradable artificial leather using agricultural and forestry waste, such as crop straw and wood, through steaming and pulping. In addition, materials based on natural materials or waste, such as apple, pineapple, cactus, and mycelium leather, are receiving increasing attention. Mycelium leather, in particular, has small fiber diameters (approximately 1-5 μm), a soft feel, and good breathability, resembling the fibrous structure of animal leather. It also possesses excellent biodegradability and is considered one of the most promising vegan leather materials. However, current mycelium materials suffer from poor bending resistance, abrasion resistance, and mechanical properties, and are prone to delamination and tearing under pressure. Therefore, improving the overall performance of mycelium materials is key to expanding their applications. Summary of the Invention

[0004] To address the aforementioned problems, the inventors, considering the growth characteristics of mycelium, developed an invention aimed at improving bending resistance, abrasion resistance, and mechanical properties. Recognizing that mycelial fibers prefer to grow on hydrophilic materials, but the growth process can degrade and damage these materials, reducing mechanical properties, the inventors proposed a method of combining hydrophilic cellulose fibers and synthetic fibers in a core-spun yarn form to create a mesh fabric. The cellulose fiber portion promotes mycelial growth, while the synthetic fiber portion ensures the product's mechanical properties. Simultaneously, the mycelium and cellulose fibers intertwine in situ, as do the cellulose and synthetic fibers, effectively improving interfacial adhesion. Furthermore, considering the hydrophilic properties of the mycelial and cellulose fibers and their interfacial compatibility with polyurethane materials, polylactic acid macromolecular segments are grafted onto the fiber surface in situ, further ensuring the final product's bending resistance, abrasion resistance, and mechanical properties.

[0005] Technical solution:

[0006] This invention provides a method for preparing high-strength biodegradable leather based on mycelial fibers, comprising the following steps:

[0007] (1) Preparation of mesh fabric

[0008] Using polylactic acid filament as the core yarn and natural or regenerated cellulose short fibers as the covering yarn, cellulose polylactic acid core-spun yarn is spun, and then mesh fabric is obtained through structural design and weaving.

[0009] (2) Preparation of mycelial leather base

[0010] The mesh fabric prepared in step (1) was stacked on a culture medium containing spores for solid-state fermentation. After fermentation, it was subjected to hot pressing, modification, cross-linking treatment, plasticizing treatment, polyurethane impregnation and drying in sequence to obtain mycelial leather base.

[0011] (3) Preparation of high-strength biodegradable leather

[0012] The mycelium leather base prepared in step (2) is polished, laminated, textured or embossed to obtain a high-strength biodegradable leather product based on mycelium fibers.

[0013] In one embodiment of the present invention, the polylactic acid filament in step (1) is a polylactic acid filament with a total fineness of 100D-300D.

[0014] In one embodiment of the present invention, the natural fiber in step (1) is cotton fiber, and the regenerated cellulose short fiber includes viscose short fiber and Tencel short fiber.

[0015] In one embodiment of the present invention, the mass ratio of cellulose short fibers to polylactic acid in the cellulose polylactic acid core-spun yarn of step (1) is 1:1-2.

[0016] In one embodiment of the present invention, the mesh size of the mesh fabric in step (1) is 2-5 mm, and the fabric weight is 100-200 g / m². 2 Furthermore, the mesh size of the fabric is 3-5 mm.

[0017] In one embodiment of the present invention, the culture medium containing spores in step (2) is prepared by the following method:

[0018] Corn cobs, bran, flour and water are mixed and sterilized. Then, sterile water containing spores is evenly sprayed onto the surface of the culture medium and cultured in the dark for 5 days at 28°C and 65% humidity.

[0019] In one embodiment of the present invention, the spores refer to, but are not limited to, any one or more combinations of the following: Ganoderma lucidum, oyster mushroom, shiitake mushroom, straw mushroom, button mushroom, enoki mushroom, lion's mane mushroom, white jade mushroom, king oyster mushroom, button mushroom, wood ear fungus, silver ear fungus, chanterelle, morel, gentiana, bamboo fungus, and schizophyllum commune spores.

[0020] In one embodiment of the present invention, the mass ratio of corn cob, bran, and flour is 3:1:1.

[0021] In one embodiment of the invention, the water content is 60% of the total mass of the corn cob, bran, and flour.

[0022] In one embodiment of the present invention, the hot pressing temperature in step (2) is 60-120°C and the time is 1-3 min.

[0023] In one embodiment of the present invention, the modification in step (2) is to first impregnate the hot-pressed mycelium fiber / mesh fabric composite base fabric with a catalyst, and then soak it in lactide at 120°C. By performing in-situ ring-opening polymerization of lactide on the surface of the mycelium fiber, the surface grafting modification of the mycelium fiber by polylactic acid molecular chain segments is achieved, and unreacted lactide monomers are removed by rinsing with ethanol.

[0024] In one embodiment of the present invention, the crosslinking treatment in step (2) refers to dipping and rubbing the modified mycelial fiber / mesh fabric composite base fabric three times in an aqueous solution of 1-10 (w / w)% citric acid, butanetetracarboxylic acid or ethylene glycol diglycidyl ether, and then drying it at 100-120°C for 30-60 min.

[0025] In one embodiment of the present invention, the plasticizing treatment in step (2) refers to immersing and rinsing the cross-linked composite base fabric three times in an aqueous solution of 1-10 (w / w)% glycerol, propylene glycol or dibutyl phthalate, and then drying it to remove water.

[0026] In one embodiment of the present invention, the impregnation of polyurethane in step (2) refers to the process of immersing and rolling the plasticized composite base fabric three times in a mixed solution containing 20-80 wt% bio-based waterborne polyurethane, 0.5-2 wt% thickener carboxymethyl cellulose, and 1-5 wt% pore-forming agent salt particles.

[0027] Furthermore, the mixed solution contains 40-60 wt% bio-based waterborne polyurethane.

[0028] In one embodiment of the present invention, the prepared mycelium leather base needs to be polished, laminated, textured or embossed in order to obtain a biodegradable leather product with excellent comprehensive properties such as water vapor permeability, bending resistance, abrasion resistance and mechanical properties.

[0029] The present invention provides a high-strength biodegradable leather based on the above method.

[0030] The present invention also provides the application of the above-mentioned high-strength biodegradable leather in the fields of home sofas, car seats, clothing and footwear.

[0031] Beneficial effects

[0032] 1. The present invention utilizes a core-spun yarn composed of cellulose fiber and polylactic acid fiber, which takes into account both the requirements of mycelial growth and ensuring mechanical properties.

[0033] 2. Using core-spun yarn to design fabrics with different mesh sizes as a three-dimensional scaffold for mycelial fiber growth enhances the interfacial adhesion between mycelium and fabric, and further ensures the bending resistance, abrasion resistance and mechanical properties of the final leather products.

[0034] 3. By grafting polylactic acid molecular chain segments onto the surface of mycelial fibers, hydrophobic modification of hydrophilic mycelial fibers is achieved, which is more conducive to their interfacial adhesion with polyurethane and helps to improve the bending resistance, abrasion resistance and mechanical properties of the final leather products.

[0035] 4. This invention, while achieving comprehensive performance improvement, selects cellulose fiber and biodegradable polylactic acid fiber as raw materials, thus preserving the overall biodegradable characteristics of the mycelial material. Furthermore, this invention uses water-based polyurethane instead of solvent-based polyurethane, making it safer and more environmentally friendly, with the advantage of less environmental pollution.

[0036] 5. The high-strength biodegradable leather products prepared by the method of this invention contain 60-90% biodegradable components and have a water vapor permeability of 1-5 mg / m³. 2It has a bending resistance of 10,000-30,000 cycles, an abrasion resistance of 800-2,500 cycles, a breaking strength of 30-50 MPa, and an elongation at break of 50-200%, exhibiting excellent overall performance. Detailed Implementation

[0037] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0038] Water vapor permeability test: The test method for water vapor permeability of leather in GB / T 1811-1993 was adopted.

[0039] Bending resistance test: The test was conducted according to the method described in GB / T 4689.9-1984.

[0040] Abrasion resistance test: At 23±2℃, the surface of the abrasion machine is observed after rotating a certain number of revolutions under a load of 1kg.

[0041] Mechanical property testing: The sample was cut into thin strips of 1×10cm and subjected to tensile testing on a universal testing machine at a tensile speed of 5cm / min.

[0042] Example 1

[0043] Using cotton fiber as the covering yarn and 120D polylactic acid filament as the core yarn, cellulose / polylactic acid core-spun yarn is produced at a mass feed ratio of 1:1, and then woven to a weight of 150g / m². 2 , Mesh fabric with 3mm mesh openings.

[0044] Preparation of culture medium: The culture medium was prepared by mixing 60% corn cob, 20% wheat bran, and 20% flour. Then, 60% water by weight of the culture medium was added, and the mixture was stirred evenly and sterilized. Subsequently, sterile water containing Ganoderma lucidum spores was evenly sprayed onto the surface of the culture medium and cultured in the dark at 28°C and 65% humidity for 5 days.

[0045] A culture medium was prepared using 10 g / L soluble starch, 1.5 g / L soybean peptone, 20 g / L glucose, 0.75 g / L potassium dihydrogen phosphate, 1.5 g / L magnesium sulfate, and 0.1 g / L vitamin B1. The above-mentioned mesh fabric was immersed in the culture medium for 12 hours, then removed, air-dried at room temperature, and sterilized.

[0046] The sterilized mesh fabric was placed over the culture medium that had been cultivated for 5 days and cultured for another week for solid-state fermentation (the mesh fabric serves as a three-dimensional grid support for the mycelial fiber propagation during solid-state fermentation, while the cellulose component provides nutrients for mycelial growth). During this process, the mycelial fibers grow along the cotton fibers of the core-spun yarn fabric and become entangled and intertwined with them. After cultivation, the fabric and mycelial layer were cut off together and hot-pressed at 80℃ and 5MPa pressure for 3 minutes.

[0047] Subsequently, the mycelium composite material obtained by hot pressing was immersed in a 2wt% stannous octoate ethanol solution. After the ethanol evaporated, it was immersed in molten lactide at 120℃ for 10 hours. Then, the unreacted lactide monomers on the surface were cleaned with ethanol to obtain a modified mycelium / mesh fabric composite base with polylactic acid macromolecular segments grafted onto the surface of the mycelium fibers.

[0048] Next, after three dips and three nips in a 5% citric acid aqueous solution, the mycelium was dried at 120°C under tension for 30 minutes. This process utilized the unreacted hydroxyl groups on the surface of the mycelium fibers and the hydroxyl groups on the surface of residual cellulose to induce cross-linking reactions between mycelium fibers, between cotton fibers and mycelium, and between cotton fibers, thereby fixing the relative positions of the fibers. The cross-linked mycelium composite material was then immersed in a 5% glycerol aqueous solution, subjected to three dips and three nips, and then dried to remove water, yielding the plasticized mycelium composite material.

[0049] A mixed solution consisting of 40 wt% bio-based waterborne polyurethane, 1 wt% carboxymethyl cellulose, and 2 wt% salt granules was prepared. The plasticized mycelial composite material was then dipped and rolled three times in the solution, followed by drying under tension to remove moisture, thus obtaining mycelial leather base.

[0050] Following conventional microfiber leather processing methods, the aforementioned base is sanded, laminated, and embossed to produce a high-strength biodegradable leather product based on mycelial fibers.

[0051] Calculations show that the content of biodegradable components in this leather product is approximately 85%, and its water vapor permeability is measured to be 3.8 mg / m³. 2 •h, bending resistance is 22,000 cycles, abrasion resistance is 1,700 cycles, breaking strength is 36 MPa, and elongation at break is 78%.

[0052] Comparative Example 1

[0053] The cotton fiber / polylactic acid core-spun yarn mesh fabric in Example 1 was replaced with a polylactic acid filament mesh fabric of the same specifications (same weight, same mesh size), while other preparation processes and methods remained unchanged, resulting in a biodegradable leather product. The calculated content of biodegradable components in this leather product was approximately 55%, and the measured water vapor permeability was 0.8 mg / m³. 2•h, breaking elongation 60%. The significant decrease in the content of degradable components and water vapor permeability is mainly because it is difficult to provide a hydrophilic environment for mycelial fiber growth in pure polylactic acid fabrics. This results in slow and low growth of mycelial fibers, and the inability to form a porous structure between fibers. Consequently, the PU impregnation process results in a composite material of polylactic acid mesh fabric and PU, leading to a significant decrease in its water vapor permeability.

[0054] Comparative Example 2

[0055] The cotton fiber / polylactic acid core-spun yarn mesh fabric in Example 1 was replaced with a cotton fiber mesh fabric of the same specifications (same weight, same mesh size), while other preparation processes and methods remained unchanged, resulting in a biodegradable leather product. The flexural strength was measured at 15,000 cycles, the abrasion resistance at 500 cycles, the breaking strength at 12 MPa, and the elongation at break at 35%. It is speculated that the cotton fiber is easily decomposed by microorganisms during mycelial growth, which would lead to a significant decrease in the flexural strength, abrasion resistance, and mechanical properties of the final leather product.

[0056] Comparative Example 3

[0057] The cotton fiber / polylactic acid core-spun yarn mesh fabric in Example 1 was replaced with a mesh fabric of the same specifications (same weight, same mesh size) made of cotton fiber and polylactic acid twisted yarn. Other preparation processes and methods remained unchanged, resulting in a biodegradable leather product. The abrasion resistance was measured at 650 cycles, the breaking strength at 28 MPa, and the elongation at break at 65%. The decrease in abrasion resistance and mechanical properties may be due to the microorganisms decomposing parts of the cotton fibers to varying degrees during mycelial fiber cultivation, causing the mesh fabric structure to loosen, thus leading to a decrease in abrasion resistance and mechanical properties.

[0058] Comparative Example 4

[0059] The modification step following hot pressing of the mycelium fiber / mesh fabric composite base fabric in Example 1 was removed, and crosslinking and other steps were directly performed to obtain a biodegradable leather product. The flexural strength was measured to be 18,000 cycles, the abrasion resistance to be 1,500 cycles, the tensile strength to be 25 MPa, and the elongation at break to be 55%. The decrease in flexural strength, abrasion resistance, and mechanical properties compared to Example 1 may be due to poor interfacial compatibility between the hydrophilic mycelium fibers, residual cotton fibers, and polyurethane.

[0060] Comparative Example 5

[0061] Based on Example 1, the mesh size of the mesh fabric was increased to 10 mm, while other preparation processes and methods remained unchanged, resulting in a biodegradable leather product. The abrasion resistance was measured to be 600 cycles.

[0062] Example 2

[0063] Based on Example 1, the mesh size of the mesh fabric was increased to 5 mm, while other preparation processes and methods remained unchanged, resulting in a biodegradable leather product. The calculated content of biodegradable components in this leather product was approximately the same as in Example 1, at about 85%, and the measured water vapor permeability was 4.0 mg / m³. 2 •h, bending resistance is 22,000 cycles, abrasion resistance is 1,000 cycles, breaking strength is 38 MPa, and elongation at break is 95%.

[0064] Example 3

[0065] Based on Example 1, the concentration of the impregnated bio-based waterborne polyurethane was increased to 60%, while other preparation processes and methods remained unchanged, resulting in a biodegradable leather product. The calculated content of biodegradable components in this leather product was slightly lower than that in Example 1, approximately 80%, and the measured water vapor permeability was 3.6 mg / m³. 2 It has a bending resistance of 25,000 cycles, an abrasion resistance of 2,200 cycles, a breaking strength of 43 MPa, and an elongation at break of 72%.

[0066] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing high strength degradable leather based on mycelium fiber, characterized by, It comprises the following steps: (1) Preparation of mesh fabric The polylactic acid filament is used as core yarn and natural or regenerated cellulose short fiber is used as covering yarn to spin cellulose polylactic acid core-spun yarn, and then the mesh fabric is obtained through structure design and weaving; (2) Preparation of mycelium leather base The mesh fabric prepared in step (1) is stacked on the culture medium containing spores for solid-state fermentation. After the fermentation is completed, the mycelium leather base is obtained through hot pressing, modification, crosslinking treatment, plasticizing treatment, polyurethane impregnation and drying in sequence. (3) Preparation of high-strength degradable leather The mycelium leather base prepared in step (2) is polished, veneered, and textured or embossed to obtain the finished product of high-strength degradable leather based on mycelium fiber. The mesh size of the mesh fabric in step (1) is 2-5 mm. In step (2), the modification is that the mycelium fiber / mesh fabric composite base cloth after hot pressing is first immersed in a catalyst, and then soaked in propylene lactone at 120℃. Through in-situ ring-opening polymerization of propylene lactone on the surface of mycelium fiber, surface grafting modification of polylactic acid molecular chain segment on mycelium fiber is realized, and unreacted propylene lactone monomer is removed by ethanol washing. In step (2), the crosslinking treatment refers to that the modified mycelium fiber / mesh fabric composite base cloth is three-dip-three-roller treated in a 1-10wt% aqueous solution of citric acid, butane tetracarboxylic acid or ethylene glycol diglycidyl ether, and then dried at 100-120℃ for 30-60min. In step (2), the plasticizing treatment refers to that the crosslinked composite base cloth is three-dip-three-roller treated in a 1-10wt% aqueous solution of glycerol, propylene glycol or dibutyl phthalate, and then dried to remove water.

2. The method of claim 1, wherein, The polylactic acid filament in step (1) has a total fineness of 100D-300D; the natural fiber is cotton fiber; the regenerated cellulose short fiber includes viscose short fiber and Tencel short fiber; the mass ratio of cellulose short fiber to polylactic acid in the cellulose polylactic acid core-spun yarn is 1:1-2.

3. The method of claim 1, wherein, The mesh fabric of step (1) has a fabric weight of 100-200 g / m 2 .

4. The method of claim 1, wherein, In step (2), the culture medium containing spores is prepared by the following method: corn cob, bran, flour and water are mixed and sterilized, then sterile water containing spores is uniformly sprayed on the surface of the culture medium, and cultured at 28℃ and 65% humidity in the dark for a period of time.

5. The method of claim 1, wherein, In step (2), the hot pressing temperature is 60-120℃ and the time is 1-3min.

6. The method according to any one of claims 1 to 5, characterized in that, In step (2), the polyurethane impregnation refers to that the plasticized composite base cloth is three-dip-three-roller treated in a mixed solution containing 20-80wt% bio-based waterborne polyurethane, 0.5-2wt% thickening agent carboxymethyl cellulose and 1-5wt% pore-forming agent salt particles.

7. The high-strength degradable leather prepared by the method of any one of claims 1-6.

8. The use of the high-strength degradable leather of claim 7 in the fields of home sofas, car seats, clothing and hats.