Mycelial structure

Abstract

To provide a mycelial structure that is water-resistant, abrasion-resistant, and highly flexible. [Solution] The mycelial structure 100 of the present invention comprises a mycelial material 10 composed of a base 11 having mycelium and a polylactic acid permeation layer 12 in which polylactic acid is permeated into the mycelium, and a polylactic acid coating layer 20 provided on the surface of the polylactic acid permeation layer 12 and thicker than the polylactic acid permeation layer 12. The thickness of the polylactic acid coating layer 20 is preferably 5.0 μm or more and 100.0 μm or less. The thickness of the polylactic acid permeation layer 12 is preferably more than 0.0 μm and 30.0 μm or less. The polylactic acid is preferably biodegradable polylactic acid. The mycelial material 10 further preferably contains fibers.

Description

Technical Field

[0001] The present invention relates to a mycelium structure.

Background Art

[0002] In recent years, as products with a small environmental load, products using natural-derived materials have been demanded in the market. For example, Patent Document 1 discloses a fungal material in which a biodegradable polymer is infiltrated to improve wear resistance and water resistance. In this document, the biodegradable polymer is infiltrated deep into the fungal material, dried, and then pressure is applied at a high temperature to improve the wear resistance and water resistance of the fungal material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the polymer is infiltrated deep into the mycelium and pressure is applied at a high temperature, while the wear resistance and water resistance of the fungal material are improved, there is a problem that the material itself becomes hard and the flexibility decreases.

[0005] Therefore, there is a demand for providing a mycelium structure having water resistance and wear resistance and excellent flexibility.

Means for Solving the Problems

[0006] The mycelium structure according to an application example of the present invention is a mycelium material composed of a base having mycelium and a polylactic acid infiltration layer in which polylactic acid is infiltrated into the mycelium, and a polylactic acid coating layer provided on the surface of the polylactic acid infiltration layer and thicker than the polylactic acid infiltration layer. It has. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic longitudinal cross-sectional view of the mycelial structure according to the embodiment. [Figure 2] This is a process diagram showing the configuration of the method for producing a mycelial structure according to the embodiment. [Figure 3] Table 1 shows the composition of the mycelial structure and the evaluation results of the mycelial structure for each example and comparative example. [Modes for carrying out the invention]

[0008] The mycelial structure of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings. [1] Mycelial structure First, the mycelial structure according to the embodiment will be described.

[0009] Figure 1 is a schematic longitudinal cross-sectional view of the mycelial structure according to the embodiment. As shown in Figure 1, the mycelial structure 100 comprises a mycelial material 10 consisting of a base 11 having mycelium and a polylactic acid permeation layer 12 in which polylactic acid has permeated the mycelium, and a polylactic acid coating layer 20 provided on the surface of the polylactic acid permeation layer 12 and thicker than the polylactic acid permeation layer 12.

[0010] With this configuration, a mycelial structure 100 is obtained that has abrasion resistance, water resistance, and excellent flexibility.

[0011] More specifically, the polylactic acid-permeable layer 12, in which polylactic acid is impregnated, and the polylactic acid coating layer 20 provided on the surface of the polylactic acid-permeable layer 12, can provide excellent abrasion resistance and water resistance to the mycelial structure 100. Furthermore, because the polylactic acid coating layer 20 is thicker than the polylactic acid-permeable layer 12, the flexibility of the mycelial structure 100 can be improved.

[0012] [1-1] Mycelial material The mycelial material 10 consists of a base 11 and a polylactic acid permeable layer 12. Of the mycelial material 10, the part that has not been permeated with polylactic acid (described later) is the base 11, and the part that has been permeated with polylactic acid is the polylactic acid permeable layer 12.

[0013] [1-1-1] Components contained in mycelial material The mycelial material 10 contains at least mushroom mycelium.

[0014] [1-1-1-1] Mushroom mycelium Mushroom hyphae are the fibrous structures that make up the mycelium of mushrooms. The types of mushrooms are not particularly limited, but examples include Agaricus arvensis, Agrocybe brasiliensis, Amylomyces rouxii, species of the genus Amylomyces, Armillaria mellea, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Ceriporia lacerata, Coprinus comatus, Fibroporia vaillantii, Fistulina hepatica, and Flammulina bertipes. Velutipes), Fomitopsis officinalis, Ganoderma sessile, Ganoderma tsugae, Ganoderma lucidum, Hericium erinaceus, Hypholoma capnoides, Hypholoma sublaterium, Inonotus obliquus, Lactarius chrysorrheus, Macrolepiota procera, Morchella angusticeps, Myceliophthora thermophila, Neurospora crassa Penicillium crassa), Penicillium camembertii, Penicillium chrysogenum, Penicillium rubensRubens), Phycomyces blakesleeanus, Pleurotus djamor, Pleurotus ostreatus, Polyporus squamosus, Psathyrella aquatica, Rhizopus microspores, Rhizopus oryzae, Schizophyllum commune, Streptomyces venezuelae, Stropharia rugosoannulata, Thielavia terrestris, Ustilago Examples include maydis, shiitake mushrooms (Lentinula genus), maitake mushrooms (Meripilus genus), maitake mushrooms (Grifola genus), giant gizzard shad mushrooms (Leucopaxillus genus), bracket fungi (Fomitopsis genus), and matsutake mushrooms (Tricholoma genus).

[0015] A mycelium is a collection of multiple mushroom hyphae. In this invention, the term "mycelium" refers not only to mycelium formed by the growth of mushroom hyphae, but also to mycelium formed by artificially assembling mushroom hyphae. In the following description, mushroom hyphae will also be simply referred to as "hyphae."

[0016] The average diameter of the hyphae is preferably set to be thinner than the average diameter of the fibers (fibers other than hyphae) described later. This makes it easier to impart a smooth texture derived from the hyphae to the mycelial structure 100.

[0017] The average diameter of the hyphae is not particularly limited, but is preferably between 0.1 μm and 10.0 μm, and more preferably between 0.3 μm and 5.0 μm. If the average diameter of the hyphae is within the above range, the texture of the mycelial structure 100 can be particularly enhanced.

[0018] The average diameter of the hyphae is measured as follows. First, the hyphal structure 100 is magnified and observed to obtain an image such that 100 or more hyphae are contained within one image. Next, 10 or more hyphal images are randomly extracted, and the width of the hyphal images is measured. Then, the average value of the measured values is taken as the average diameter of the hyphae. Incidentally, the average diameter of fibers (fibers other than hyphae) described later is also measured in the same manner.

[0019] The average length of the hyphae is not particularly limited, but is preferably 0.001 mm or more and 3.0 mm or less, more preferably 0.010 mm or more and 2.0 mm or less, and even more preferably 0.050 mm or more and 1.0 mm or less. If the average length of the hyphae is within the above range, for example, when the hyphal structure 100 is formed into a sheet shape, the hyphae are oriented along the surface of the hyphal structure 100 and the hyphae are moderately intertwined with each other. Thereby, the texture of the hyphal structure 100 can be particularly enhanced.

[0020] The average length of the hyphae is measured as follows. First, the hyphal structure 100 is magnified and observed to obtain an image such that 100 or more hyphae are contained within one image. Next, 10 or more hyphal images are randomly extracted, and the maximum length that can be taken within the hyphal images is measured. Then, the average value of the measured values is taken as the average length of the hyphae. Incidentally, the average length of fibers (fibers other than hyphae) described later is also measured in the same manner.

[0021] The hyphae preferably contain chitin. Chitin is contained as a component of the cell wall constituting the hyphae. Chitin is a high molecular polysaccharide having N-acetylglucosamine, in which an acetamide group is added to glucose, as a structural unit. Since chitin has a hydroxyl group, when a crosslinking agent described later is used for imparting strength, the hyphae are easily crosslinked by the crosslinking agent. Thereby, the abrasion resistance and water resistance of the hyphal structure 100 can be made even more excellent.

[0022] [1-1-1-2] Fibers other than hyphae The mycelial material 10 may also contain fibers other than mycelium (hereinafter simply referred to as "fibers"). This can further enhance the abrasion resistance and water resistance of the mycelial structure 100.

[0023] The fibers used are not particularly limited, and a wide range of fiber materials can be used. Examples of fibers include natural fibers such as animal fibers and plant fibers, organic fibers, inorganic fibers, and chemical fibers such as organic-inorganic composite fibers. Specifically, examples include cellulose, silk, wool, cotton, hemp, kenaf, flax, ramie, jute, Manila hemp, sisal, coniferous trees, and broadleaf trees. These may be used individually or in appropriate mixtures. They may also be used as regenerated fibers after purification or other processes.

[0024] Examples of raw materials for the fibers include recycled paper and recycled cloth, but materials containing at least one of the above-mentioned fibers can be used. Furthermore, the fibers may be subjected to various surface treatments. The material of the fibers may be a pure substance, or it may be a material containing multiple components such as impurities, additives, and other components.

[0025] Among these, fibers containing cellulose are more preferable. Cellulose contains many hydroxyl groups in its molecular structure. Therefore, when using the crosslinking agent described later, it reacts easily with the crosslinking agent, making it easier to improve the abrasion resistance and water resistance of the mycelial structure 100.

[0026] The average diameter of the fibers is not particularly limited, but it is preferably thicker than the average diameter of the hyphae. Specifically, it is preferably 1.0 μm or more and 100.0 μm or less, and more preferably 3.0 μm or more and 50.0 μm or less. If the average diameter of the fibers is within the above range, the abrasion resistance of the mycelial structure 100 can be particularly enhanced.

[0027] The average length of the fibers is not particularly limited, but is preferably 0.001 mm to 5.0 mm, more preferably 0.002 mm to 3.0 mm, and even more preferably 0.003 mm to 2.0 mm. If the average length of the fibers is within the above range, for example, the fibers will be oriented along the surface of the mycelial structure 100 and will intertwine with each other to a suitable degree. This makes it possible to particularly enhance the abrasion resistance of the mycelial structure 100.

[0028] [1-1-1-3] Starch The mycelial material 10 may contain starch. For example, the mycelium can be coated with starch by impregnating it with a starch solution and then evaporating the water. This can further improve the abrasion resistance of the mycelial structure 100.

[0029] Starch is a molecule formed by the polymerization of multiple α-glucose molecules via glycosidic bonds. Starch may be a linear molecule or may contain branches. As starch, for example, starch derived from various plants can be used. More specifically, for example, starch derived from grains such as corn, wheat, and rice; legumes such as broad beans, mung beans, and adzuki beans; tubers such as potatoes, sweet potatoes, and tapioca; wild grasses such as bracken and kudzu; and palms such as sago palm can be used.

[0030] The starch may be modified starch. Examples of modified starch include acetylated adipic acid cross-linked starch, acetylated starch, oxidized starch, sodium octenyl succinate starch, hydroxypropyl starch, hydroxypropylated phosphate cross-linked starch, phosphorylated starch, phosphate esterified phosphate cross-linked starch, urea phosphorylated esterified starch, sodium starch glycolate, and high amylose corn starch. The starch may also be denatured starch. Examples of denatured starch include those obtained by processing or denaturing starch, specifically dextrin.

[0031] [1-1-1-4] Plasticizer The mycelial material 10 may contain a plasticizer. Examples of plasticizers include sugar alcohols, oils, adipic acid ester plasticizers, phthalic acid ester plasticizers, trimellitic acid ester plasticizers, polyester plasticizers, (meth)acrylic acid ester polymers, ethylene copolymer elastomers, chlorinated polyethylene (CPE), (meth)acrylic resins (PMMA), polystyrene resins (PS), polyvinyl acetate resins (PVAc), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), and the like.

[0032] Examples of sugar alcohols include maltitol, lactitol, tetriitol, pentitol, hexitol, erythritol, sorbitol, xylitol, mannitol, and glycerin.

[0033] The mycelial material 10 preferably contains at least one of glycerin and oil. This further enhances the flexibility of the mycelial structure 100.

[0034] The glycerin used is not particularly limited and may be natural glycerin or synthetic glycerin.

[0035] Oil is a hydrophobic liquid and is generally an ester of an alcohol and a fatty acid. Examples of oils include those derived from plants, animals, and minerals. Examples of vegetable oils include castor oil, rapeseed oil, soybean oil, coconut oil, linseed oil, olive oil, avocado oil, sesame oil, perilla oil, cottonseed oil, safflower oil, corn oil, rice bran oil, camellia oil, coconut oil, and peanut oil. More specifically, epoxidized vegetable oils such as epoxidized soybean oil (ESBO) and epoxidized linseed oil (ELSO) are also examples.

[0036] When mycelium contains glycerin or oil, its hydrophilicity decreases. This inhibits the penetration of polylactic acid into the mycelium, as described later, allowing the thickness of the polylactic acid penetration layer 12 to be reduced. This increases the flexibility of the mycelial structure 100.

[0037] The plasticizer content in the mycelial material 10 is not particularly limited, but is preferably 10.0% by mass or less, more preferably 0.1% by mass or more and 7.0% by mass or less, and even more preferably 0.5% by mass or more and 4.0% by mass or less. This results in a mycelial structure 100 that achieves both abrasion resistance and flexibility.

[0038] [1-1-1-5] Other components contained in mycelial material Furthermore, the mycelial material 10 may contain other components. Examples of other components include stabilizers, antioxidants, UV absorbers, lubricants, flame retardants, antistatic agents, colorants, and fillers.

[0039] The content of other components in the mycelial material 10 is not particularly limited, but is preferably 10.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 5.0% by mass or less.

[0040] [1-1-1-6] Others The substances contained in the mycelial material 10 may be cross-linked with a cross-linking agent. The cross-linking agent reacts with hydroxyl groups contained in the mycelium and fibers when heat is applied. This improves the abrasion resistance and water resistance of the mycelial structure 100.

[0041] The crosslinking agent is not particularly limited as long as it is an organic compound having multiple carboxyl groups. Examples of crosslinking agents include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; dicarboxylic acids having hydroxyl groups such as tartaric acid and malic acid; tricarboxylic acids such as citric acid and aconitic acid; and amino acids having multiple carboxyl groups such as aspartic acid and glutamic acid. One or a mixture of two or more of these can be used.

[0042] The mycelial material 10 may be subjected to treatments that alter the chemical bonding of the mycelium, such as ozone treatment, deacetylation, sebacic acid, or tannins. These treatments can further improve the abrasion resistance and water resistance of the mycelial structure 100.

[0043] The treatments to improve the abrasion resistance, water resistance, and flexibility of the mycelial structure 100 may be performed individually or in combination as appropriate.

[0044] [1-1-2] Base The base 11 is the portion of the mycelial material 10 that has not been permeated with polylactic acid, which will be described later. The base 11 supports the polylactic acid permeated layer 12 and the polylactic acid coated layer 20, which will be described later.

[0045] The base 11 may contain components other than those described in [1-1-1]. For example, it may contain polylactic acid that has fallen out of the polylactic acid permeation layer 12 described later after the production of the mycelial structure 100.

[0046] The content of components other than those described in [1-1-1] in the base portion 11 is not particularly limited, but is preferably 10.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 5.0% by mass or less.

[0047] [1-1-3] Polylactic acid permeation layer The polylactic acid permeation layer 12 is the portion of the mycelial material 10 in which polylactic acid has permeated the mycelium. "Penetration of polylactic acid into the mycelium" means that polylactic acid has permeated the mycelial body, which is formed by the aggregation of mycelium. The polylactic acid permeation layer 12 has the function of improving the abrasion resistance and water resistance of the mycelial structure 100. Furthermore, the polylactic acid permeation layer 12 is located between the base 11 and the polylactic acid coating layer 20 (described later), and also has the function of connecting the two.

[0048] The polylactic acid permeated layer 12 has higher rigidity compared to the base 11 because it is permeated with polylactic acid. Therefore, in order to improve the flexibility of the mycelial structure 100, it is desirable for the thickness of the polylactic acid permeated layer 12 to be thinner. For this reason, the thickness of the polylactic acid permeated layer 12 is preferably greater than 0.0 μm and 30.0 μm or less, more preferably between 0.5 μm and 20.0 μm, and even more preferably between 1.0 μm and 10.0 μm. This makes it possible to improve the abrasion resistance and water resistance of the mycelial structure 100 while also making it more flexible.

[0049] The thickness of the polylactic acid permeation layer 12 is measured from photographs of the cross-sectional structure of the mycelial structure 100 taken with a scanning electron microscope. The thickness of each layer, as described later, is measured in the same manner.

[0050] The polylactic acid contained in the polylactic acid permeation layer 12 is preferably biodegradable polylactic acid. This reduces the environmental burden due to the carbon neutrality of the raw materials.

[0051] For biodegradable polylactic acid, raw materials such as those primarily derived from various plant-based starches can be used. More specifically, starches derived from corn, sugarcane, potatoes, wheat, etc., can be used.

[0052] [1-2] Polylactic acid coating layer The polylactic acid coating layer 20 is provided on the surface of the polylactic acid permeable layer 12 and contains at least polylactic acid. This allows the polylactic acid coating layer 20 to enhance the abrasion resistance and water resistance of the mycelial structure 100.

[0053] The thickness of the polylactic acid coating layer 20 is preferably 5.0 μm to 100.0 μm, more preferably 30.0 μm to 95.0 μm, and even more preferably 60.0 μm to 90.0 μm. This allows the polylactic acid permeable layer 12 to further improve the abrasion resistance and water resistance of the mycelial structure 100, as well as to improve its flexibility.

[0054] The thickness of the polylactic acid coating layer 20 is greater than that of the polylactic acid permeation layer 12. This reduces the thickness of the highly rigid polylactic acid permeation layer 12, allowing for a balance between the flexibility of the mycelial structure 100 and its abrasion resistance and water resistance.

[0055] [1-3] Uses of mycelial structure The mycelial structure 100 can be molded into various shapes, for example, depending on its intended use. More specifically, it can be molded into sheet form, board form, web form, etc. Specific examples of applications include paper, nonwoven fabric, wallpaper, wrapping paper, colored paper, drawing paper, recording media, decorative sheets, fiberboard, filters, liquid absorbents, sound absorbers, cushioning materials, mats, and the like.

[0056] The mycelial structure 100 according to this embodiment is particularly useful as a natural material, such as a leather substitute (alternative leather), because it has excellent abrasion resistance, water resistance, and flexibility.

[0057] [1-4] Others In this embodiment, the mycelial structure 100 preferably has a maximum strain in the elastic region of 4.0% to 40.0% in the stress-strain curve showing the relationship between the stress (MPa) applied by a tensile test and the strain (%) at that time, more preferably 5.0% to 30.0%, and even more preferably 7.0% to 25.0%. With such a configuration, the flexibility of the mycelial structure 100 can be particularly improved.

[0058] For tensile testing, for example, an Autograph AGS-5kNX (manufactured by Shimadzu Corporation) can be used.

[0059] The conditions for each component described in [1-1-1] may differ between the base 11 and the polylactic acid permeable layer 12, or they may be the same.

[0060] [2] Method for producing mycelial structures Next, we will describe an example of a method for producing the mycelial structure 100 mentioned above.

[0061] Figure 2 is a process diagram showing the configuration of the method for producing a mycelial structure according to the embodiment. The method for producing the mycelial structure 100 shown in Figure 2 comprises a mycelial preparation step S102 for preparing the mycelium, a coating step S104 for applying a polylactic acid coating agent to the mycelium, and a drying step S106 for drying the applied polylactic acid coating agent.

[0062] [2-1] Mycelial preparation process In the mycelial preparation step S102, first, a mycelial body containing mycelium is prepared. The mycelial body is formed, for example, by gathering many mycelium and shaping or papermaking them into a sheet. The mycelial body may be in the form of a flat plate or shaped into a predetermined shape. The mycelium may be defibrated from mushroom mycelium. This allows the mycelial body to be shaped into a desired shape without being restricted by the shape of the mushroom mycelium before defibration. For defibration of mushroom mycelium, for example, a method of applying mechanical energy is used. In particular, by using a defibration machine, it is possible to defibrate the mushroom mycelium and obtain mycelium while suppressing significant damage to the mycelium. The defibration method may be a wet method, but a dry method is preferred. A dry method refers to a method of defibration in the air, such as the atmosphere, rather than in a liquid such as water. An impeller mill capable of dry defibration is preferably used as the defibration machine.

[0063] The mycelium may be formed by mixing, for example, mycelium, starch, plasticizer, crosslinking agent, and fibers, and then applying heat to the mixture. In this case, various types of agitators are used for mixing. Examples of agitators include mechanical agitators, air agitators, and ultrasonic agitators. The timing of mixing each of the above components may be the same or different for each component. For example, two or more components may be mixed simultaneously, or each component may be mixed sequentially.

[0064] Furthermore, the mycelium may be prepared after being treated to improve its abrasion resistance, water resistance, and flexibility. Examples of treatments to improve abrasion resistance, water resistance, and flexibility include mixing with fibers, impregnation in a starch solution, impregnation in a solution containing at least one of glycerin and oil, addition of a crosslinking agent, and ozone treatment, as mentioned above.

[0065] Furthermore, mycelium obtained through cultivation may be used as the mycelium itself. By inoculating a culture medium with mycelial spawn and culturing it, mycelium can be obtained in which the grown hyphae spread throughout the entire culture medium. The culture medium may be a solid medium or a liquid medium.

[0066] The culture medium may contain components that improve abrasion resistance, water resistance, and flexibility. Examples of components that improve abrasion resistance, water resistance, and flexibility include, as mentioned above, starch, plasticizers, crosslinking agents, and fibers. In addition to these components, the culture medium may also contain nutrients necessary for the growth of mushroom mycelium, gelling agents, etc. On the other hand, starch may be used as a nutrient.

[0067] In the case of solid culture media, it is preferable to use media molded into a sheet shape. This simplifies or eliminates secondary processing, and allows for the efficient production of sheet-shaped mycelium. Liquid culture media, for example, consist of starch, plasticizers, crosslinking agents, fibers, etc., dispersed in a dispersion medium such as water. When using liquid culture media, management and handling of the media are relatively easy because it is in liquid form. Furthermore, since stirring and other operations are possible with liquid culture media, it is easy to achieve uniformity and speed up the cultivation process.

[0068] Culture conditions such as culture temperature, culture time, and humidity are set appropriately according to the type of mycelium and culture medium.

[0069] In the mycelium obtained through cultivation, the hyphae are connected in a three-dimensional manner. This allows for greater flexibility to be imparted to the mycelial structure 100.

[0070] The mycelium obtained by culturing may be shaped as needed. This makes it possible to obtain mycelium in the desired shape.

[0071] [2-2] Coating process Next, in coating step S104, a polylactic acid coating agent is applied to one side of the prepared mycelium to form a uniform film. As a result, some of the applied polylactic acid coating agent remains on the surface of the mycelium without penetrating, while some penetrates the mycelium. Note that the polylactic acid coating agent penetrates only a part of the mycelium, not the entire mycelium. In other words, there are parts of the mycelium that have not been penetrated by the polylactic acid coating agent.

[0072] The polylactic acid coating agent is a liquid containing polylactic acid. More specifically, it is preferably a dispersion containing polylactic acid and water. The polylactic acid coating agent may contain any additives as needed. Examples of additives include condensing agents, antioxidants, stabilizers, and lubricants.

[0073] The method of applying the coating agent is not particularly limited, but for example, a bar coater, dipping, blade, or spray can be used.

[0074] [2-3] Drying process In drying step S106, the mycelium coated with polylactic acid is dried. Drying is carried out under atmospheric pressure. Drying is preferably carried out at a temperature between 23°C (room temperature) and 100°C. Since the flexibility of the mycelial structure 100 decreases as the drying temperature increases, it is preferable to dry at the lowest possible temperature.

[0075] When the moisture is evaporated by the drying process S106, the portion of the mycelium surface that remained without penetration of the polylactic acid coating agent becomes the polylactic acid coating layer 20. The portion of the mycelium that was penetrated by the polylactic acid coating agent becomes the polylactic acid penetration layer 12. The portion of the mycelium that was not penetrated by the polylactic acid coating agent becomes the base 11. The mycelial material 10 is composed of the base 11 and the polylactic acid penetration layer 12.

[0076] The amount of polylactic acid coating agent that penetrates can be adjusted by the drying conditions. In other words, the ratio of the thickness of each layer in the mycelial structure 100 can be adjusted by the drying conditions.

[0077] For example, the shorter the time between the application of the polylactic acid coating agent and the start of drying, the shorter the time the polylactic acid coating agent has to penetrate the mycelium. As a result, the amount of penetration into the mycelium decreases. Consequently, the polylactic acid penetration layer 12 becomes thinner, and the polylactic acid coating layer 20 becomes thicker.

[0078] [3] Effects of the above embodiment As described above, the mycelial structure according to the embodiment comprises a mycelial material consisting of a base having mycelium and a polylactic acid permeable layer in which polylactic acid is permeated into the mycelium, and a polylactic acid coating layer provided on the surface of the polylactic acid permeable layer and thicker than the polylactic acid permeable layer.

[0079] This configuration yields a mycelial structure that is abrasion-resistant, water-resistant, and highly flexible.

[0080] Furthermore, in the mycelial structure according to the above embodiment, the thickness of the polylactic acid coating layer is preferably 5.0 μm or more and 100.0 μm or less.

[0081] This configuration improves the abrasion resistance and water resistance of the mycelial structure, while also making it more flexible.

[0082] Furthermore, in the mycelial structure according to the above embodiment, the thickness of the polylactic acid permeation layer is preferably greater than 0.0 μm and less than or equal to 30.0 μm.

[0083] This configuration allows for improved flexibility while enhancing the abrasion resistance and water resistance of the mycelial structure.

[0084] Furthermore, in the mycelial structure according to the above embodiment, it is preferable that the polylactic acid is biodegradable polylactic acid.

[0085] With this configuration, the carbon neutrality of the raw materials for the mycelial structure can reduce the environmental burden.

[0086] Furthermore, in the mycelial structure according to the above embodiment, it is preferable that the mycelial material further includes fibers.

[0087] This configuration further enhances the abrasion resistance and water resistance of the mycelial structure.

[0088] Furthermore, in the mycelial structure according to the above embodiment, the mycelial material preferably contains at least one of glycerin and oil. This configuration allows for further enhancement of the flexibility of the mycelial structure.

[0089] Furthermore, in the mycelial structure according to the above embodiment, it is preferable that the maximum strain in the elastic region of the stress-strain curve, which shows the relationship between the stress (MPa) applied by the tensile test and the strain (%) at that time, is between 4.0% and 40.0%. This configuration can particularly improve the flexibility of the mycelial structure.

[0090] Furthermore, in the mycelial structure according to the above embodiment, the mycelial material may include mycelia composed of hyphae connected in a three-dimensional manner.

[0091] With this configuration, the hyphae are connected in a three-dimensional manner, which allows for greater flexibility in the mycelial structure.

[0092] Furthermore, in the mycelial structure according to the above embodiment, the mycelial material may include defibrated mycelium.

[0093] With this configuration, the mycelium can be molded into a desired shape, without being constrained by the shape of the mushroom mycelium before fibrillation.

[0094] Although the mycelial structure of the present invention has been described above based on preferred embodiments, the present invention is not limited thereto. For example, the mycelial structure according to the present invention may be obtained by replacing each part of the above embodiment with any component having a similar function, or by adding any component to the above embodiment. [Examples]

[0095] Next, specific examples of the present invention will be described, but the present invention is not limited thereto. In the following examples, processes and measurements where the temperature conditions are not specified were performed at room temperature (23°C).

[0096] [4] Production of mycelial structure [4-1] Example 1 First, the mycelium obtained by culturing the spawn (Reishi mushroom) was subjected to abrasion resistance and water resistance treatment. For the abrasion resistance and water resistance treatment, the mycelium was impregnated in a starch solution at room temperature for 160 minutes, then removed and heated at 100°C to evaporate the water. A 20% by mass starch aqueous solution was used as the starch solution.

[0097] Next, the mycelium, which had been treated to impart abrasion resistance and water resistance, was subjected to a flexibility-imparting treatment. For the flexibility-imparting treatment, the mycelium was impregnated with a glycerin-containing solution at room temperature, allowing glycerin to penetrate between the mycelium, and then heated to evaporate the moisture. A glycerin solution with a concentration of 20% by mass was used.

[0098] Next, a thin, uniform layer of polylactic acid coating agent was applied to one side of the mycelium that had undergone the flexibility-enhancing treatment, and allowed to penetrate. A bar coater was used for application. A dispersion containing polylactic acid and water was used as the polylactic acid coating agent.

[0099] Subsequently, the mycelium coated with polylactic acid was placed in a constant temperature bath and dried at 80°C. The mycelial structure of Example 1 was obtained in this manner.

[0100] [4-2] Examples 2-4 and Comparative Examples 1-3 Except for changing the manufacturing conditions of the mycelial structure as shown in Figure 3 (Table 1), the mycelial structures of Examples 2-5 and Comparative Examples 1-3 were obtained in the same manner as in Example 1. Note that only Example 5 did not undergo treatment to impart abrasion resistance, water resistance, and flexibility to the mycelium.

[0101] [5] Evaluation of mycelial structure [5-1] Water resistance and abrasion resistance First, test specimens were prepared by punching out the mycelial structure. A white cotton cloth for friction was then moistened with water to a state of approximately 100% by mass. Next, using a JSPS-type friction durability tester AB-301 (manufactured by Tester Sangyo Co., Ltd.), the white cotton cloth attached to the friction element was rubbed against the test specimen under a load of 0.067 MPa. The number of cycles until the test specimen tore due to friction was measured, and the water resistance and abrasion resistance were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.

[0102] A: The number of friction cycles until the test piece breaks is 100 or more. B: The number of friction cycles until the test specimen breaks is between 50 and 100. C: The number of friction cycles until the test specimen breaks is between 10 and 49. D: Fewer than 10 friction cycles before the test specimen breaks.

[0103] [5-2] Flexibility First, test specimens were prepared by punching out the mycelial structure. Next, tensile tests were performed on the test specimens using an Autograph AGS-5kNX (Shimadzu Corporation) in accordance with JIS P 8113:2006. A stress-strain curve was created showing the relationship between the stress (MPa) applied by the tensile test and the strain (%) at that time, and the elastic region was identified. Then, the flexibility was evaluated based on the maximum strain in the elastic region according to the following evaluation criteria. A higher value for the maximum strain in the elastic region indicates better flexibility. The evaluation results are shown in Table 1.

[0104] A: Maximum strain in the elastic range is between 8.0% and 15.0%. B: Maximum strain in the elastic region is 6.0% or more and less than 8.0% C: Maximum strain in the elastic region is between 2.0% and less than 6.0% D: Maximum strain in the elastic region is less than 2.0%

[0105] As is clear from Table 1, the mycelial structures of each of the above examples possessed abrasion resistance and water resistance, as well as excellent flexibility. In contrast, satisfactory results could not be obtained with the mycelial structures of each comparative example. [Explanation of Symbols]

[0106] 10...Mycelial material, 11...Base, 12...Polylactic acid permeation layer, 20...Polylactic acid coating layer, 100...Mycelial structure, S102...Mycelial preparation process, S104...Coating process, S106...Drying process

Claims

1. A mycelial material consisting of a base having mycelium and a polylactic acid permeation layer in which polylactic acid has permeated the mycelium, A polylactic acid coating layer is provided on the surface of the polylactic acid permeable layer, and is thicker than the polylactic acid permeable layer. A mycelial structure characterized by having the following features.

2. The mycelial structure according to claim 1, wherein the thickness of the polylactic acid coating layer is 5.0 μm or more and 100.0 μm or less.

3. The mycelial structure according to claim 1 or 2, wherein the thickness of the polylactic acid permeation layer is greater than 0.0 μm and less than or equal to 30.0 μm.

4. The mycelial structure according to claim 1 or 2, wherein the polylactic acid is biodegradable polylactic acid.

5. The mycelial structure according to claim 1 or 2, wherein the mycelial material further comprises fibers.

6. The mycelial structure according to claim 1 or 2, wherein the mycelial material comprises at least one of glycerin and oil.

7. In a stress-strain curve showing the relationship between the stress (MPa) applied by a tensile test and the strain (%) at that time, The mycelial structure according to claim 1 or 2, wherein the maximum strain in the elastic region is 4.0% or more and 40.0% or less.

8. The mycelial structure according to claim 1 or 2, wherein the mycelial material includes a mycelium composed of mycelia connected in a three-dimensional manner.

9. The mycelial structure according to claim 1 or 2, wherein the mycelial material includes the defibrated mycelium.

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