Method for preparing finished leather substitutes

Abstract

The present invention relates to a method for preparing a finished leather substitute, the method comprising providing a sheet material grown from mycelium, the sheet material exhibiting a top surface layer and a bottom surface, wherein the method comprises applying at least one finish coating only on the bottom surface.

Description

[0001] The present invention relates to a process for preparing a finished leather substitute, a finished leather substitute obtainable by this process and its use. Background of the Invention

[0002] Leather is used in various applications, including furniture decoration, clothing, shoes, luggage (luggage, bags), handbags and accessories and automotive applications. Currently, the skin of animals is used as the raw material of natural leather. Synthetic leather has been developed, and it is not made of animal skin or hide (hide, rawhide) as genuine leather, but is made of natural and / or synthetic fibers coated with synthetic polymers or the like. Although many materials have been used, most of synthetic leathers are made up of knitted polyester base and polyvinyl chloride coating with polyurethane. The processing and lifespan and lifespan of these microplastics, non-biodegradable plastic-based products are still far from being environmentally friendly. In addition, this synthetic leather lacks the quality, durability and reputation of natural leather.

[0003] Therefore, the current trend is towards the use of non-petroleum-based materials, especially materials of plant origin. Fungus-based materials, especially those of the mycelium type, are natural materials (whether composite or not) and are obtained by growing fungal materials. Their growth is controlled to obtain a variety of shapes, sizes, and densities. Materials obtained from mycelium, such as those described in International Patent Application WO2018014004 (Mycoworks), US Patent Application 2015 / 0033620 or US Patent 9,485,917 (Ecovative Design) or International Patent Application WO2020237201 (Bolt threads), make it possible to prepare materials in the form of thick sheets that can be used as substitutes for leather.

[0004] However, before they can be used as leather substitutes, these raw materials need to be processed, usually stabilised and plasticised as well as ennobled. Ennoblement can involve colouring the material, changing its flexibility, mechanical properties, density and adding some coating or finishing to the surface of the material to improve colour uniformity, water resistance, smooth touch. Summary of the Invention

[0005] The inventors have recognized that the finishing of the top surface of mycelium-grown materials as leather substitutes is not entirely satisfactory. They lack uniformity, with some areas on the top surface being denser, more or less hydrophobic, or more or less porous. This results in uneven topcoat adhesion, coloration, and surface plasticization and lubrication. Furthermore, the inventors have demonstrated that the top surface is impervious to aqueous solution penetration due to its high surface fiber density and more hydrophobic nature.

[0006] The inventors then made the counter-intuitive decision to apply a finish coating to the bottom surface and use the finished bottom surface as the visible portion of the leather substitute. In other words, the inventors turned the material over and finished only the bottom surface.

[0007] Therefore, the present invention provides a method for preparing a finished leather substitute, the method comprising

[0008] a) providing a sheet material from which mycelium grows from bottom to top, the sheet material exhibiting a top surface layer and a bottom surface layer defined in terms of the growth of said mycelium;

[0009] b) contacting the sheet material with an aqueous solution comprising a lubricant;

[0010] c) drying it;

[0011] d) applying at least one finish coating only on said bottom surface.

[0012] The finish can be applied in one or more coats simultaneously or successively.

[0013] Another subject of the present invention is a finished leather substitute obtainable by the process as defined herein.

[0014] A further subject of the invention is the use of the finished leather substitute as a substitute for leather in the fashion, accessories, household appliances and other furniture industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram showing the growth of a mycelium, defining a top surface and a bottom surface, as described in international patent application WO2018014004 (from which this figure is reproduced).

[0016] Figure 2A schematic diagram of the method of the present invention. The top layer is the side in contact with the air, and the bottom layer is the side closest to the nutrient medium during mycelial growth. The inner portion is made of mycelium (A. left), but another material, such as a textile, can also be incorporated (B. right) to ensure overall mechanical resistance. After processing, turning, and finishing the material, the final outer portion of the finished article is the lower portion of the starting mycelial sheet material.

[0017] Figure 3A and Figure 3B are SEM photographs (scanning electron microscope) of the top surface (3A) and the bottom surface (3B).

[0018] Figure 4 Yes Figure 2 Picture of the resulting processed mycelium sheet material (bottom) as described in . DETAILED DESCRIPTION

[0019] Mycelium growth

[0020] Filamentous fungi grow their bodies as an expanding and interconnected network of thread-like cells called hyphae, directly within the food they consume as nutrients.

[0021] Filamentous fungi have a natural tendency to join together smaller pieces of branching, colonial hyphae into larger constituent wholes, thereby assembling and weaving strands and sheets of tissue called mycelium.

[0022] The mycelium used in the present invention can be derived from any desired fungal inoculum, i.e. any desired amplifiable colony of a desired fungal strain. For example, the fungal species can be selected from the classes ascomycetes, basidiomycetes, deuteromycetes, oomycetes and zygomycetes, preferably from the family Ganodermataceae of the order Polyporales, preferably Ganoderma lucidum, Ganoderma tsugae, Ganoderma applanatum, Ganoderma resinaceum and Ganoderma oregonense. Other candidates include Trametes versicolor, Trametes pubescens, Schizophyllum commune and Polyporous squamosus.

[0023] In a preferred embodiment, the mycelium is Ganoderma mycelium.

[0024] Sheet material grown from mycelium can be obtained by any method known in the art, for example using the method described in patent application WO2018014004 (Mycoworks).

[0025] As used herein, the term "sheet" refers to a layer of solid material having a generally flat or planar shape and a high ratio of surface area to thickness.

[0026] Within the enclosure or prior to being introduced into the enclosure, a first fungal inoculum may be introduced into a nutritious substrate, which may contain a mixture of discrete particles and nutrients, such as lignocellulosic waste, to provide an even distribution of the fungi throughout. The substrate is left to colonize. An intermediate layer may be established over the open surface of the colonized substrate to control the interaction of the developing fungal tissue structure with the substrate. In specific examples, cellulose-based materials such as cotton or rayon are often used because they are both biodegradable and non-preferred food sources for Ganoderma, meaning that they retain strength throughout the growth process in a way that lignin-containing materials do not. The presence of a uniform intermediate material atop the substrate enables a consistent surface from which the fungal tissue can grow, thereby supporting even expansion of the fungal hyphae into the environment. Live fungal hyphae grow from the substrate and through the intermediate layer. See Figure 1 .

[0027] In certain embodiments, the fungal material can be periodically manipulated to direct growth in a manner that imparts desired characteristics, including density, uniformity, and increased strength. The growth of the fungal material can be directed, for example, in predetermined patterns such as orthogonal structures, lattices, and other two- or three-dimensional structures.

[0028] Fungal tissue can be modified and directed during growth to achieve uniform characteristics across the surface, or engineered to exhibit different local qualities by manipulating the growing tissue or adding particles, fibers, meshes, fabrics and other additives, armatures and components.

[0029] The middle layer may be delaminated from the nutrient source from which the material has grown to terminate further growth of the material, or the fungal tissue layer may be delaminated from the middle layer (which is left in place and optionally reused).

[0030] In a particular embodiment, the sheet material grown from mycelium has been obtained by a process comprising the steps of:

[0031] a. Provide a nutritious vehicle;

[0032] b. growing fungal tissue from the nutrient carrier, the fungal tissue comprising fungal hyphae;

[0033] c. allowing fungal tissue to grow and extend through the porous material defining the intermediate layer;

[0034] d. extending a portion of the fungal tissue through the porous material away from the nutrient carrier to grow into an administrable space, wherein the fungal tissue within the space defines at least one sequential layer of fungal material;

[0035] e. guiding changes in the composition or growth pattern of at least one fungal hyphae in at least one layer;

[0036] f. separating at least a portion of the fungal material from the nutrient carrier; and

[0037] g. altering said part of the fungal material by physical or chemical means.

[0038] The middle layer is generally not easily bonded to the fungal tissue and provides uniform initial growth conditions, thereby achieving uniform growth of the fungal tissue.The porous material is preferably micro-perforated or woven.

[0039] After manipulating the growing fungal tissue to induce changes in growth pattern, the fungal material can be pulled off the middle layer, thereby promoting continued growth of the fungal material.

[0040] In another embodiment, the material obtained by the growth of mycelium can be a self-supporting material, such as that obtained by the method described in US Patent 9,485,917 (Ecovative Design).

[0041] In this method, hyphae are grown through a substrate, the net shape of which is defined by the physical dimensions of the shell.

[0042] In the next step, the substrate (now held tightly together by the mycelial network) is separated from the shell, and any internal shells or elements are separated when desired.

[0043] Composite materials

[0044] In certain embodiments, the sheet material grown from mycelium further comprises another material not grown from mycelium, optionally embedded within the mycelium.

[0045] Materials can be incorporated into growing fungal tissue while the fungal material is still alive to guide growth and / or produce composite materials. In one embodiment, cellulose-based, synthetic, or other organic fibers (including various textile forms (e.g., woven, knitted, fulled, felted) of preferred lengths and structural characteristics) are deposited on the exposed surface of the growing fungal tissue to allow the growth of the composite material. The composition and organization of the composite fibers enable the fungal tissue to be engineered, enhancing the mechanical properties of the overall material, including tensile strength and compressive strength.

[0046] In alternative embodiments, fungal tissue can be grown through 2D and 3D matrices and objects of various materials to produce composites with desired characteristics and qualities. Such added layers of material can comprise any material (pore size greater than 1 micron) through which fungal cells can grow. These layers can be pressed onto or near the surface of the growing cells or otherwise impressed onto its surface, or placed between two or more layers of growing fungal material so that these reinforcement layers are then incorporated into the fungal tissue.

[0047] Materials not grown from mycelium preferably include cotton, silk, linen, polyester, polyamide, wool, nylon, Cellulose, or any regenerated cellulose fiber (also known as "rayon"), including viscose, modal and lyocell (Tencell / Lenzing AG), or any combination thereof.

[0048] Top surface layer and bottom surface layer

[0049] Sheet materials grown from mycelium are generally not homogeneous and show structural polarity, with a top surface layer that is more hydrophobic than the bottom layer.

[0050] The top surface layer may be defined as containing more fungal hyphae tips than the bottom surface layer and / or as the surface that is in contact with air (or gas) during mycelial growth.

[0051] Typically, the top surface layer and the bottom surface layer are defined in the sense of the growth of the mycelium from the bottom to the top.

[0052] The top and bottom surface layers exhibit different structural properties. The top surface layer is typically less porous and more hydrophobic than the bottom surface layer.

[0053] It will therefore be understood that the sheet material grown from mycelium (used as the starting material in the present invention) No A material obtained or obtainable by a process comprising breaking up mycelium and converting it into a paste, optionally adding a polymer. Such a material does not exhibit a structural polarity with a top surface layer that is more hydrophobic than a bottom layer.

[0054] lubricating

[0055] The process of the invention comprises a step b) of contacting the sheet material with an aqueous solution comprising a lubricant. This step is also called a lubrication step or a fatliquoring step, since it introduces oil into the material.

[0056] The contacting step may include soaking the material with the solution, such as by plunging it into a drum, washing machine, stable basin, or other suitable treatment means.

[0057] In a preferred embodiment, the aqueous solution comprising the lubricant contains a fatliquor and an emulsifier.

[0058] Fatting agent can comprise various types of oil such as mineral oil, synthetic oil, oil based on animal and plant or its combination and mixture usually.The oil based on animal fat can be such as fish oil, lanolin, beeswax or lard.The oil based on vegetable fat can be such as castor oil, coconut oil, cotton oil, olive oil, rapeseed oil, linseed oil.For example, the oil based on synthetic oil can be derived from the vegetable oil or animal oil of modification or synthetic fatty acid or fatty alcohol or modification.These fatting agents are preferably obtained by sulfation, sulfitation or the sulfonic acid that forms described oil, so that they are soluble or emulsifiable in water.

[0059] Other plasticizers and wetting agents well known in the art may be used to make the material permeable to the microdroplets of oil.Various fatliquors contain emulsified oil in water with the addition of other compounds such as ionic and nonionic emulsifiers, surfactants, soaps, and sulfates.

[0060] Plasticizing and stabilization

[0061] In a preferred embodiment, step b) of the method further comprises plasticizing and / or stabilizing the sheet.The steps of plasticizing and stabilizing can be performed simultaneously with or in sequence with lubrication.

[0062] In a preferred embodiment, plasticization and / or stabilization can be carried out by contacting the sheet with at least one polyol and / or fatliquor, optionally in combination with at least one polycarboxylic acid.

[0063] Examples of plasticizers include glycerol and its esters, sorbitol, polyethylene glycol, polypropylene glycol, propylene glycol, citric acid, oleic acid, oleic acid polyols and their esters, epoxidized triglyceride vegetable oils, castor oil, pentaerythritol, fatty acid esters, carboxylate-based plasticizers, trimellitates, adipates, sebacates, maleates, bioplasticizers, and combinations thereof.

[0064] Preferably, the sheet may be contacted with glycerol, preferably in combination with citric acid, preferably in water.

[0065] The reagents can be added to the drum or any device that feeds the material.

[0066] It may further be advantageous to massaging the sheet to achieve complete penetration.

[0067] Tanning and dyeing

[0068] In a preferred embodiment, step b) of the method further comprises contacting the sheet material with tannins, preferably wherein the aqueous solution comprising the lubricant further comprises tannins. Preferred tannins are condensed tannins, hydrolysable tannins and / or synthetic tannins.

[0069] As used herein, the term "tannin" generally refers to any molecule that forms a strong bond with a protein structure. The most frequently used tannin type is a vegetable tannin, i.e. the tannin extracted from trees and plants, and chrome tannins such as chromium sulfate (III). Other examples of tannins include modified naturally derived polymers, biopolymers and metals other than chromium such as salts of aluminum, for example aluminosilicate (sodium aluminosilicate, potassium aluminosilicate etc.) or alun. Also synthetic tannins may be used, such as those obtained by the condensation of sulfonated aromatic compounds and / or unsulfonated aromatic compounds with formaldehyde and / or urea.

[0070] Various dyes can be used to impart color to the sheet material, such as acid dyes, direct dyes, disperse dyes, sulfur dyes, synthetic dyes, reactive dyes (reactive dyes, reaction dyes), pigments (such as black iron oxide, titanium dioxide and cobalt blue) and natural dyes. In some embodiments, before applying the dye solution, the material is immersed in an alkaline solution to promote dye absorption and penetration into the material. In some embodiments, before applying the dye solution, the material is pre-soaked in ammonium chloride, ammonium hydroxide and / or formic acid to promote dye absorption and penetration into the material, preferably before fixing the dye by reducing the pH.

[0071] In some embodiments, tannins may be added to the dye solution.

[0072] In various embodiments, the plasticizer is added after the addition of the dye or during the addition of the dye. In various embodiments, the plasticizer can be added with the dye solution.

[0073] In various embodiments, the material may be subjected to mechanical processing or agitation while the dye solution is being applied to promote dye absorption and penetration into the material.

[0074] dry

[0075] The sheet material which has been wetted with an aqueous solution comprising a lubricant and optionally subjected to various treatments with plasticizers and / or stabilizers, tannins and / or dyes can then typically be cured by crosslinking, typically by heating at 50-100°C, preferably 70-80°C, preferably for 10 to 60 minutes.

[0076] The drying step c) of the process then involves placing the material at room temperature or in a ventilated oven (at about 20-40°C) or in a tannery dryer tunnel for several days.

[0077] In a preferred embodiment, the polymerization between the polycarboxylic acid (e.g., citric acid), the polyol (e.g., glycerol), and the mycelial material induces stabilization of the smooth appearance of the surface and strengthening of the entire material. Furthermore, it allows the material to maintain suppleness after drying.

[0078] Finishing

[0079] The method of the invention comprises a step d) of applying at least one finishing coat to the dried material.

[0080] The finishing method may use surface coating techniques such as padding, spraying or roller coating. Preferably, the deposition of the finishing coat is performed by roller coating to lay down and compact the mycelium fibers while lining the surface.

[0081] Mechanical methods such as polishing, staking, scraping and embossing may also be used.

[0082] One or more finish coats may be applied.

[0083] The finish coating is typically applied by contacting the dried sheet with an aqueous solution containing the polymer emulsion, crosslinker and optionally pigments and / or fillers. In a preferred embodiment, several solutions are applied.

[0084] The finish coating may comprise at least one monomer and possibly at least one catalyst, the method further comprising the step of polymerizing the monomer. In another embodiment, the finish coating may comprise at least one polymer, at least one crosslinking agent and possibly at least one catalyst, and the method further comprising the step of crosslinking the polymer.

[0085] In a preferred embodiment, a first aqueous layer, called a primer coat, is applied to promote adhesion. The primer may comprise a dispersion of an alcohol and a polymer. After the primer dries, a subsequent coating is applied, which may contain an emulsion of several resins and a crosslinking agent. At this stage, colorants, pigments, or fillers may be added to the mixture to impart or adjust the color of the final material (i.e., the finished leather substitute). For example, the polymer emulsion may comprise an anionic, cationic, or neutral polyurethane or acrylate in an aqueous medium and / or in the presence of a cationic or nonionic anionic surfactant and / or in the presence of an alcoholic organic solvent.

[0086] Finally, one or more layers called topcoats are usually applied to protect the material from wear and discoloration, as well as to provide the finished leather substitute with its final tactile and aesthetic qualities. It may contain a mixture of polymers, silicone agents, and cross-linking agents.

[0087] Optionally, crosslinking agents such as polycarbodiimides or polyisocyanates or polyaziridines can be added in order to harden the deposited layer and ensure better mechanical resistance.

[0088] If desired, surface treatment, texturizing or polishing steps may be performed to impart texture to the material or to smooth the surface.

[0089] In a particular embodiment, the finishing step d) may comprise the incorporation of fillers of natural origin such as microcrystalline cellulose or cellulose nanofibrils and / or ground shells.

[0090] In another preferred embodiment, the finishing step d) comprises applying an emulsion of natural polymers such as casein, albumin or other proteins or synthetic polymers such as polyurethanes and polyacrylates.

[0091] Typically, a period of 24 hours is beneficial for the finish to stabilize and dry before proceeding to the next step.

[0092] Finished leather substitutes

[0093] The product obtainable by the process described herein is a finished leather substitute that can be used as a leather substitute in the fashion, accessories, home appliance and other furniture industries.

[0094] It can be used in particular for producing bags, shoes, watch straps, belts or wallets.

[0095] The figures and examples illustrate the invention without limiting its scope.

[0096] Example

[0097] Mycelial sheet material was obtained as described in international patent application WO2018014004 (Mycoworks).

[0098] Figure 3A and 3B SEM images of the top and bottom surfaces show differences in structure and porosity. The top surface is less porous, and the mycelial hyphae appear compacted and fused, while the bottom surface is more porous and less dense. The absorption time of a water droplet was measured using a contact angle goniometer. The absorption times for the top and bottom surfaces were 27 and 1.5 seconds, respectively, while the contact angles at t = 0 seconds were 73° and 43°, respectively. These results confirm that the bottom surface is more permeable to water and more hydrophilic than the top surface.

[0099] The mycelium sheet was then subjected to the following treatments, also as Figure 2 As shown:

[0100] - Soaking: First soak the mycelium sheet in a water-based solution at room temperature and static conditions.

[0101] - Stabilization / lubrication: The material is then stabilized in a drum using a bath at 40 to 60°C containing a mixture of water, glycerol, vegetable tanning agent, fatliquor, dye, before being fixed under acidic conditions.

[0102] - Plasticization: The material is plasticized by adding glycerol and citric acid to water and massaging at room temperature to achieve complete and uniform penetration of the mixture.

[0103] - Drying: the material is then crosslinked by heating at 50 to 80°C for 5 to 120 minutes and finally dried at 25 to 40°C.

[0104] - Finishing: The finishing coat is then applied only on the bottom surface layer by spraying various aqueous solutions containing polymer emulsions comprising: water, fillers (colloidal resins), polymer and wax emulsions, as well as softeners containing oils and penetrating solutions containing wetting agents.

[0105] Finished product (see Figure 4 ) shows excellent properties as a leather substitute, especially in terms of wear resistance and bending resistance. In addition, it is not affected by weather changes or ultraviolet rays.

Claims

1. A method for preparing a finished leather substitute, the method comprising: a) providing a sheet material from which mycelium grows from bottom to top, the sheet material exhibiting a top surface layer and a bottom surface layer defined in terms of the growth of said mycelium; b) contacting the sheet material with an aqueous solution comprising a lubricant and a tannin; c) drying it; d) applying at least one finish coating only on the bottom surface, wherein the finish coating is applied by contacting a mixture comprising a polymer emulsion and optionally pigments and / or fillers on the bottom surface of the dried sheet.

2. The method of claim 1, wherein the contacting in step d) is spraying.

3. The method of claim 1 or 2, wherein step b) further comprises plasticizing and / or stabilizing the sheet.

4. The method of claim 3, wherein the plasticizing and / or stabilizing of the sheet is carried out by contacting the tanned sheet with at least one polyol and / or fatliquor, optionally in combination with at least one polycarboxylic acid.

5. The method of claim 1 or 2, wherein the mycelium is Ganoderma mycelium.

6. Finished leather substitute obtainable by the method according to any one of claims 1 to 5.

7. Use of the finished leather substitute according to claim 6 as a leather substitute in accessories.

8. Use of the finished leather substitute according to claim 6 as a leather substitute in household appliances and other furniture industries.

9. The use according to claim 7, for preparing bags, shoes, watch straps or belts.

10. The use according to claim 7, for preparing a wallet.

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