A method for preparing bio-based leather using fungal fruiting bodies

Abstract

This invention discloses a method for preparing bio-based leather using fungal fruiting bodies, belonging to the field of bio-based materials technology. The method includes the following steps: first, the fungal fruiting bodies are pulverized and surface-grafted in an aqueous medium to obtain modified fungal fruiting bodies; then, they are mixed with water to form a fungal fruiting body dispersion; modified cellulose short fibers and an anti-settling agent are added and stirred evenly to obtain a fungal fruiting body slurry; subsequently, waterborne polyurethane, a plasticizer, a pore-forming agent, and a crosslinking agent are added and stirred evenly; after dehydration and concentration, the mixture is extruded and dried to obtain a fungal fruiting body composite base; the composite base is processed according to conventional microfiber leather processing methods to obtain the finished bio-based leather. The bio-based leather prepared by this method can achieve an appearance and performance similar to natural leather. The preparation process is environmentally friendly and pollution-free. The finished leather has a high bio-based content and good biodegradability, making it valuable for applications in bags, home furnishings, and clothing decoration.

Description

Technical Field

[0001] This invention relates to a method for preparing bio-based leather using fungal fruiting bodies, belonging to the field of bio-based materials technology. Background Technology

[0002] Humans have a long history of using natural leather, but the quantity of raw natural leather hides is limited, and its production process is energy-intensive and highly polluting, placing a heavy burden on the environment. In recent years, new requirements have been put forward for the safety of natural leather itself, with strict restrictions on toxic chemicals such as hexavalent chromium, pentachlorophenol, and free formaldehyde in natural leather, which has put enormous pressure on the development of natural leather.

[0003] Based on this, companies and researchers are accelerating the development of new materials to replace natural leather. Among them, microfiber synthetic leather, with its superior performance, has become the best alternative. However, the production process of microfiber synthetic leather also uses a large amount of organic solvents, and the microfibers used have few hydrophilic groups, resulting in poor moisture absorption and transfer capabilities, leading to a significant gap in moisture-wicking performance compared to natural leather. Therefore, finding new raw materials with excellent performance for the development of leather products is of great significance.

[0004] Chinese patent CN109736097A discloses the introduction of hydrophilic bacterial cellulose into traditional microfibers, thereby improving the breathability and moisture permeability of leather. Chinese patents CN115418866A and CN113638237A both disclose methods for preparing novel leather materials using plant bast fibers, such as pineapple leaf fiber, coconut shell fiber, and hemp fiber. CN111455681A discloses a method for preparing novel leather materials using agricultural and forestry waste, such as crop straw and wood, through steaming and pulping.

[0005] In addition, products based on natural materials or waste, such as apples, pineapples, and cactus leather, are receiving increasing attention. Among numerous natural resources, fruiting bodies are sporogenic structures of higher fungi, composed of organized mycelium. They are a renewable natural resource that can be produced through fermentation processes and culture media, inoculation, and incubation. The culture media can be agricultural biomass or industrial waste. The resulting fruiting bodies have a complex shape, varying depending on the fungus species, including umbrella-shaped, pen-shaped, head-shaped, ear-shaped, tongue-shaped, spherical, flower-shaped, and branch-shaped forms. Mushrooms and other fungi consumed in daily life fall into the category of fruiting bodies. Fruiting bodies are hydrophilic, porous, and have widely available and inexpensive raw materials. The production process does not produce environmental pollution and consumes carbon dioxide, making them truly carbon-negative materials.

[0006] The preparation of bio-based leather products based on fruiting bodies is of great economic and environmental significance; however, it is difficult to make leather products from fruiting body materials alone. Directly compounding them with polyurethane as fillers has problems such as poor compatibility with polyurethane interface, low filler content, poor wear resistance, and poor mechanical properties. Summary of the Invention

[0007] To address the shortcomings and deficiencies of existing technologies, namely the inability to directly composite with traditional solvent-based polyurethane due to the high hydrophilicity and moisture content of fungal fruiting bodies, the high energy consumption of composite after drying, and the poor interfacial compatibility between the fruiting bodies and polyurethane, this invention provides a method for preparing bio-based leather using fungal fruiting bodies. The method involves first modifying the surface of the fruiting bodies through grafting, then pulping, grinding, and finally adding water-based polyurethane in situ to create a leather base fabric, resulting in leather products with excellent breathability, abrasion resistance, and mechanical properties.

[0008] The first objective of this invention is to provide a method for preparing bio-based leather using fungal fruiting bodies, the method comprising the following steps:

[0009] (1) The fungal fruiting bodies are crushed and surface grafted in an aqueous medium to obtain modified fungal fruiting bodies; then they are mixed with water, crushed and milled to form a fungal fruiting body dispersion, and then modified cellulose short fibers and anti-settling agent are added and stirred evenly to obtain fungal fruiting body slurry.

[0010] (2) Add water-based polyurethane, plasticizer, pore-forming agent and crosslinking agent to the fungal fruiting body slurry prepared in step (1), stir evenly, dehydrate and concentrate, squeeze dry, then treat with hot water to remove the pore-forming agent, and dry to obtain fungal fruiting body composite base.

[0011] (3) The fungal fruiting body composite leather obtained in step (3) is polished, laminated and embossed according to the conventional microfiber leather processing method to obtain a bio-based leather product based on fungal fruiting bodies.

[0012] In one embodiment, the fungal fruiting body in step (1) includes one or more of the following: enoki mushroom, tea tree mushroom, king oyster mushroom, white jade mushroom, lion's mane mushroom, morel mushroom, or northern wind mushroom.

[0013] In one embodiment, the surface grafting modification in step (1) specifically refers to coating the surface of the fungal fruiting body with tannic acid in an aqueous solution, and using the Schiff base reaction of tannic acid with octadecylamine to obtain the surface-grafted octadecyl modified fungal fruiting body.

[0014] In one embodiment, the mass ratio of the modified fungal fruiting body to water in step (1) is 1:1 to 2.

[0015] In one embodiment, the pulverization in step (1) is carried out using a high-speed pulverizer with a rotation speed of 20,000 to 25,000 r / min.

[0016] In one embodiment, the disc grinding in step (1) refers to grinding on a disc mill with a disc mill speed of 1000-2000 r / min.

[0017] In one embodiment, the modified cellulose short fiber mentioned in step (1) refers to the hydrophobic modification of cellulose, including one or more of modified viscose fiber, modified Tencel fiber, modified bacterial cellulose, modified cotton linter, modified bamboo fiber, and modified hemp fiber.

[0018] In one embodiment, the modified cellulose short fibers in step (1) have a fiber length of 5-10 mm and are added at 30-60% (w / w) of the dry weight of the fungal fruiting body.

[0019] In one embodiment, the preparation of the modified viscose short fiber in step (1) includes the following:

[0020] Unmodified viscose staple fibers are dried in an oven to remove moisture, then added to molten lactide, followed by stannous octoate catalyst, and reacted at 100-120℃ for 2-5 hours. The viscose staple fibers are then removed, and the ungrafted polylactic acid components on the surface of the viscose staple fibers are removed with dichloromethane to obtain modified viscose fibers with polylactic acid segments grafted onto the surface.

[0021] In one embodiment, the anti-settling agent in step (1) is one or more of carboxymethyl cellulose, sodium alginate, or starch.

[0022] In one embodiment, the amount of anti-settling agent added in step (1) is 1-5% of the dry weight of the fungal fruiting body, w / w.

[0023] In one embodiment, the apparent viscosity of the fungal fruiting body slurry in step (1) is 1 to 3 Pa·s.

[0024] In one embodiment, the waterborne polyurethane in step (2) is a bio-based waterborne polyurethane, and the amount added is 10-50% of the dry weight of the fungal fruiting body, w / w.

[0025] In one embodiment, the plasticizer in step (2) is one or more of glycerol, propylene glycol, or dibutyl phthalate.

[0026] In one embodiment, the amount of plasticizer added in step (2) is 1-5% of the dry weight of the fungal fruiting body, w / w.

[0027] In one embodiment, the pore-forming agent in step (2) is one or more of polyethylene glycol, polyvinylpyrrolidone, or NaCl salt particles with a molecular weight of 20000 g / mol.

[0028] In one embodiment, the amount of pore-forming agent added in step (2) is 1-3% of the dry weight of the fungal fruiting body, w / w.

[0029] In one embodiment, the crosslinking agent in step (2) is one or more of citric acid, butanetetracarboxylic acid, or ethylene glycol diglycidyl ether.

[0030] In one embodiment, the amount of crosslinking agent added in step (2) is 1-10% of the dry weight of the fungal fruiting body, w / w.

[0031] In one embodiment, the dehydration and drying in step (2) is vacuum filtration dehydration, the drying temperature is 100-130℃, the time is 20-30 min, and the cross-linking reaction occurs simultaneously during this process.

[0032] A second objective of this invention is to provide a bio-based leather product prepared by the method described above.

[0033] A third objective of this invention is to provide an application of the aforementioned bio-based leather products in the manufacture of bags, footwear, and decorative items.

[0034] The beneficial effects of this invention are:

[0035] (1) The bio-based leather prepared by this invention can achieve a similar appearance and performance to natural leather. The entire preparation process is environmentally friendly and pollution-free. The finished leather has a high bio-based content and good biodegradability. This product has application value in the fashion field, such as bags, home furnishings, and clothing decoration.

[0036] (2) This invention avoids the performance differences caused by different fruiting body morphologies and compositions by pulverizing, pulping and grinding fungal fruiting bodies into an aqueous dispersion, and the method has wide applicability; in addition, by modifying the surface of fungal fruiting bodies and combining it with an anti-settling agent, the uniform mixing of fruiting bodies and polyurethane is ensured, and the excellent interfacial interaction between fruiting bodies and polyurethane is also ensured; surface modification in an aqueous medium is used instead of surface modification in a solvent, and water-based polyurethane is used instead of solvent-based polyurethane, which is safe and environmentally friendly and has the advantage of low environmental pollution.

[0037] (3) The bio-based leather products prepared by the method of the present invention have a fungal fruiting body filling content of 50-80%, a bio-based content of 70-90%, and a water vapor permeability of 1-2.5 mg / cm³. 2It has a bending resistance of 15,000-30,000 cycles, an abrasion resistance of 1,200-2,500 cycles, a breaking strength of 40-60 MPa, and an elongation at break of 50-150%, exhibiting excellent overall performance. Detailed Implementation

[0038] 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.

[0039] The testing method involved in this invention:

[0040] Water vapor permeability test: The test method for water vapor permeability of leather in GB / T 1811-1993 was adopted.

[0041] Bending resistance test: The test was conducted according to the method described in GB / T 4689.9-1984.

[0042] 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.

[0043] 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.

[0044] The preparation of the modified viscose fiber involved in this invention includes:

[0045] First, 20g of unmodified viscose fiber was dried in an oven at 105℃ for 2 hours to remove moisture. Then, it was added to 20g of molten lactide, and 5‰ of stannous octoate was added as a catalyst. The mixture was reacted at 120℃ for 5 hours. The viscose fiber was then removed, and the ungrafted polylactic acid components on the surface of the viscose fiber were removed with dichloromethane to obtain modified viscose fiber with polylactic acid segments grafted onto its surface.

[0046] Bio-based waterborne polyurethane: purchased from Shenzhen Tongtai Chemical Technology Co., Ltd., brand name LUR10.

[0047] Conventional unmodified viscose fiber: purchased from Xinxiang Chemical Fiber Co., Ltd., filaments with specifications of 120D / 30F, cut to the required length by myself.

[0048] Example 1

[0049] A method for preparing bio-based leather using fungal fruiting bodies, the method comprising the following steps:

[0050] (1) Crush enoki mushrooms into small pieces of 2-5 mm on a crusher, weigh 2.0 g of small pieces of enoki mushrooms and put them into 98 g of water. After stirring evenly, add 0.4 g of tannic acid and react at 25 °C for 24 h. Then add 100 ml of 2.0% (w / w) octadecylamine ethanol solution and react at 50 °C for 24 h. After the reaction is completed, centrifuge to obtain modified enoki mushrooms.

[0051] (2) Add water to the modified enoki mushrooms from step (1) at a mass ratio of 1:1, grind them into a paste on a high-speed pulverizer at 20000 r / min, and then grind and mix them further on a disc mill at 1500 r / min; then add 10 mm long modified viscose fiber at 50% of the mass of enoki mushrooms and disperse it evenly, then add 5% of the anti-settling agent carboxymethyl cellulose to adjust the viscosity of the system solution to 2 Pa·s to obtain enoki mushroom slurry;

[0052] (3) In the enoki mushroom slurry obtained in step (2), add 30% of the dry weight of enoki mushrooms of bio-based waterborne polyurethane, 3% (w / w) of the dry weight of enoki mushrooms of glycerol as plasticizer, 10% of the dry weight of enoki mushrooms of NaCl salt particles as pore-forming agent, and 5% (w / w) of the dry weight of enoki mushrooms of citric acid as crosslinking agent, and stir evenly; filter, dehydrate and concentrate, squeeze out water at room temperature, dry at 120℃ for 30 min, after which cook in hot water at 50℃ for 10 min to dissolve the pore-forming salt particles, and then dry in a forced-air drying oven at 100℃ to obtain a composite bass of enoki mushrooms, modified viscose fiber and polyurethane;

[0053] (4) The composite base prepared in step (3) is polished, laminated and embossed according to the conventional microfiber leather processing method to obtain the bio-based leather product based on enoki mushroom.

[0054] In this embodiment, the leather product contains 55% enoki mushroom fruiting bodies as filler, 88% bio-based components, and has a measured water vapor permeability of 1.8 mg / cm³. 2 It has a bending resistance of 22,000 cycles, an abrasion resistance of 2,100 cycles, a breaking strength of 52 MPa, and an elongation at break of 90%.

[0055] Example 2

[0056] The only difference from Example 1 is that the amount of modified viscose fiber in step (2) is changed to 30% of the mass of enoki mushrooms. All other conditions and parameters are the same as in Example 1, and bio-based leather is obtained.

[0057] The leather product prepared in this embodiment has a 62% content of enoki mushroom fruiting bodies and a bio-based component content of 85%, with a measured water vapor permeability of 2.2 mg / cm³. 2It has a bending resistance of 20,000 cycles, an abrasion resistance of 1,800 cycles, a breaking strength of 45 MPa, and an elongation at break of 85%.

[0058] Example 3

[0059] The only difference from Example 1 is that the amount of bio-based waterborne polyurethane added in step (3) is increased to 50% of the dry weight of enoki mushrooms. All other parameters and conditions are the same as in Example 1, and bio-based leather is obtained.

[0060] The leather product prepared in this embodiment has a fungal fruiting body filling content of 55%, a bio-based component content of 86%, and a measured water vapor permeability of 1.3 mg / cm³. 2 It has a bending resistance of 25,000 cycles, an abrasion resistance of 2,400 cycles, a breaking strength of 58 MPa, and an elongation at break of 120%.

[0061] Example 4

[0062] The only difference from Example 1 is that the length of the modified viscose fiber in step (2) is changed from 10 mm to 5 mm. All other parameters and conditions are the same as in Example 1, and bio-based leather is obtained.

[0063] The *Flammulina velutipes* fruiting body prepared in this embodiment had a filling capacity of 55% and a bio-based component content of 88%, which is not significantly different from that in Example 1. The measured water vapor permeability was 1.8 mg / cm³. 2 It has a bending resistance of 20,000 cycles, an abrasion resistance of 1,500 cycles, a breaking strength of 48 MPa, and an elongation at break of 75%.

[0064] Comparative Example 1

[0065] The only difference from Example 1 is that step (1) of enoki mushroom modification treatment is omitted, and enoki mushroom is directly crushed and processed according to the methods and conditions of steps (2) to (4) to obtain bio-based leather.

[0066] The bio-based leather prepared in this comparative example had little change in the amount of *Flammulina velutipes* filling and the content of bio-based components compared to Example 1, which were 55% and 88%, respectively. The measured water vapor permeability was 2.0 mg / cm³. 2 It has a bending resistance of 10,000 times, an abrasion resistance of 800 times, a breaking strength of 25 MPa, and an elongation at break of 30%.

[0067] The reason for the significant decrease in bending resistance, abrasion resistance, and mechanical properties compared to Example 1 is that the interface between the unmodified enoki mushroom and polyurethane is large, and the large number of enoki mushrooms used as fillers results in more defects inside the leather products.

[0068] Comparative Example 2

[0069] The only difference from Example 1 is that the anti-settling agent carboxymethyl cellulose in step (2) is removed. All other parameters and conditions are the same as in Example 1, and bio-based leather is obtained.

[0070] Compared to Example 1, the bio-based leather prepared in this comparative example showed a slight increase in the filling amount of *Flammulina velutipes* fruiting bodies (58%), while the bio-based component content slightly decreased to 85%. The measured water vapor permeability was 1.6 mg / cm³. 2 It has a bending resistance of 13,000 cycles, an abrasion resistance of 1,000 cycles, a breaking strength of 38 MPa, and an elongation at break of 45%.

[0071] The reason why the bending resistance, abrasion resistance and mechanical properties decreased compared to Example 1 is that without the anti-settling agent, the modified enoki mushrooms are prone to settling, which prevents them from forming a stable mixed solution with polyurethane. This further leads to uneven dispersion of enoki mushrooms in polyurethane, resulting in a decrease in the performance of the final leather products.

[0072] Comparative Example 3

[0073] The only difference from Example 1 is that the modified viscose fiber in step (2) is replaced with conventional unmodified viscose fiber. All other parameters and conditions are the same as in Example 1, and bio-based leather is obtained.

[0074] The amount of *Flammulina velutipes* fruiting body and the content of bio-based components in the bio-based leather prepared in this comparative example were not significantly different from those in Example 1, remaining at 55% and 88% respectively. The measured water vapor permeability was 2.0 mg / cm³. 2 It has a bending resistance of 17,000 cycles, an abrasion resistance of 1,000 cycles, a breaking strength of 32 MPa, and an elongation at break of 55%.

[0075] Viscose fiber mainly plays a role in wear resistance and reinforcement in bio-based leather products, but the interface with polyurethane must be properly handled. If added directly, the effect will be significantly reduced, which is why the effect was not ideal in this comparative example.

[0076] Comparative Example 4

[0077] The only difference from Example 1 is that the viscosity of the enoki mushroom slurry in step (2) is adjusted to 5 Pa·s. All other parameters and conditions are the same as in Example 1, and bio-based leather is obtained.

[0078] The amount of *Flammulina velutipes* fruiting body and the content of bio-based components in the bio-based leather prepared in this comparative example were not significantly different from those in Example 1, remaining at 55% and 88% respectively. The water vapor permeability was measured to be 1.6 mg / cm³. 2 It has a bending resistance of 12,000 cycles, an abrasion resistance of 800 cycles, a breaking strength of 30 MPa, and an elongation at break of 45%.

[0079] Excessive viscosity of the slurry mainly affects the mixing effect with the polyurethane solution, thereby reducing the uniformity of the fruiting body enoki mushroom in the final leather product and affecting wear resistance and mechanical properties.

[0080] 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 bio-based leather using fungal fruiting bodies, characterized in that, The method includes the following steps: (1) The fungal fruiting bodies are crushed and surface grafted in an aqueous medium to obtain modified fungal fruiting bodies; then they are mixed with water, crushed and milled to form a fungal fruiting body dispersion, and then modified cellulose short fibers and anti-settling agent are added and stirred evenly to obtain fungal fruiting body slurry. The surface grafting modification specifically refers to coating the surface of fungal fruiting bodies with tannic acid in an aqueous solution, and then using the Schiff base reaction of tannic acid with octadecylamine to obtain a modified fruiting body with octadecylamine grafted on the surface. The modified cellulose short fiber is a modified viscose short fiber; the preparation of the modified viscose short fiber includes the following steps: Unmodified viscose staple fibers are dried in an oven to remove moisture, then added to molten lactide, followed by stannous octoate catalyst, and reacted at 100-120°C for 2-5 hours. The viscose staple fibers are then removed, and the ungrafted polylactic acid components on the surface of the viscose staple fibers are removed with dichloromethane to obtain modified viscose fibers with polylactic acid segments grafted onto the surface. The apparent viscosity of the fungal fruiting body slurry is 1~3 Pa·s; (2) Add water-based polyurethane, plasticizer, pore-forming agent and crosslinking agent to the fungal fruiting body slurry prepared in step (1), stir evenly, dehydrate and concentrate, squeeze and dry to obtain fungal fruiting body composite base; (3) The fungal fruiting body composite leather obtained in step (2) is polished, laminated and embossed according to the conventional microfiber leather processing method to obtain a bio-based leather product based on fungal fruiting bodies.

2. The method according to claim 1, characterized in that, The fungal fruiting bodies mentioned in step (1) include one or more of the following: enoki mushroom, tea tree mushroom, king oyster mushroom, white jade mushroom, lion's mane mushroom, morel mushroom, or northern wind mushroom.

3. The method according to claim 1, characterized in that, In step (1), the mass ratio of the modified fungal fruiting body to water is 1:1~2.

4. The method according to claim 1, characterized in that, The modified cellulose short fiber in step (1) has a fiber length of 5-10 mm and is added at 30-60% of the dry weight of the fungal fruiting body, w / w.

5. The method according to claim 1, characterized in that, The waterborne polyurethane in step (2) is a bio-based waterborne polyurethane, and the amount added is 10-50% of the dry weight of the fungal fruiting body, w / w.

6. The bio-based leather product prepared by the method according to any one of claims 1 to 5.

7. The application of the bio-based leather product as described in claim 6 in the preparation of bags, footwear, and decorations.