Cellulose nanofiber-dispersed aqueous resin reinforced material

Abstract

To provide a cellulose nanofiber-dispersed aqueous resin reinforced material that is lightweight and excellent in elastic modulus.SOLUTION: A cellulose nanofiber-dispersed aqueous resin reinforced material has a cellulose nanofiber-dispersed aqueous resin in which cellulose nanofibers and an aqueous resin are impregnated into at least one substrate selected from the group consisting of a woven fabric, a nonwoven fabric, bamboo, paper, and wood (where, when the substrate is a woven fabric and / or a nonwoven fabric, the aqueous resin is not a thermoplastic resin).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a cellulose nanofiber-dispersed aqueous resin-reinforced material. [Background technology]

[0002] From components for automobiles and aircraft to sporting goods, carbon fiber reinforced plastics (CFRP) are increasingly being used in products that require lightness and strength. For example, in sporting goods, there is a demand for "lighter and stronger materials," and the use of lightweight, high-strength CFRP is progressing. However, for example, in bats, cracks occur on the surface and inside of the CFRP when the ball is repeatedly struck, so the CFRP layer is made thicker to increase static strength and impact strength. In these products, if the static strength and impact strength of CFRP are improved by 20%, it can be made thinner, and the weight can be reduced by 15 to 30%, allowing users to feel a much lighter swing feeling. However, it is difficult to further improve the static strength and impact strength of CFRP in this way.

[0003] Cellulose nanofibers (CNFs) are environmentally friendly nanofibers that can be refined from wood and other materials, and are lightweight and strong at the same time. However, it is very difficult to control the dispersion of CNFs in the base resin, and hydrophobic modification techniques and the use of organic solvents are generally considered to be the solutions. For this reason, it is generally considered difficult to apply CNFs to CFRP without hydrophobizing them.

[0004] Therefore, Patent Document 1 shows that by constructing a cellulose nanofiber layer on at least one side of a carbon fiber reinforced plastic layer, in other words, by constructing the carbon fiber reinforced plastic and the cellulose nanofiber as separate layers, the resulting material is lightweight and has excellent impact strength. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 221155 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, the material is reinforced by providing a cellulose nanofiber layer, but laminating the carbon fiber reinforced plastic and the cellulose nanofiber in separate layers is time-consuming and requires the production of separate layers, which increases the work time and costs.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide a cellulose nanofiber-dispersed aqueous resin reinforced material that is lightweight and has an excellent elastic modulus, simply and at low cost. [Means for solving the problem]

[0008] In view of the above object, the inventors conducted extensive research and found that, unlike conventional methods, by impregnating cellulose nanofibers and a thermoplastic resin into woven fabric, nonwoven fabric, bamboo, paper, wood, or the like, it is possible to easily and inexpensively produce an aqueous resin-reinforced material in which cellulose nanofibers are dispersed without forming carbon fiber reinforced plastic and cellulose nanofibers into separate layers, and that the material is lightweight and has a high elastic modulus. Based on this knowledge, the inventors conducted further research and completed the present invention. That is, the present invention includes the following configurations.

[0009] Item 1. A cellulose nanofiber-dispersed aqueous resin reinforced material, comprising at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood, and a cellulose nanofiber-dispersed aqueous resin layer impregnated with cellulose nanofibers and an aqueous resin (however, when the substrate is textiles and / or nonwoven fabrics, the aqueous resin is not a thermoplastic resin).

[0010] Item 2. The cellulose nanofiber-dispersed aqueous resin reinforced material according to Item 1, wherein the bamboo is at least one selected from the group consisting of Moso bamboo, Japanese bamboo, and Sasa bamboo.

[0011] Item 3. The cellulose nanofiber-dispersed aqueous resin reinforced material according to Item 1 or 2, wherein the paper material is at least one selected from the group consisting of Japanese paper, Western paper, processed paper, synthetic paper, and filter paper.

[0012] Item 4. The cellulose nanofiber-dispersed aqueous resin reinforced material according to any one of Items 1 to 3, wherein the wood is at least one selected from the group consisting of sawara, cypress, pine, cedar, red pine, Japanese larch, Ezo pine, linden pine, birch, elm, beech, poplar, Norway spruce, Norway scotch pine, Radiata pine, Douglas fir, Japanese larch, and North Pacific larch.

[0013] Item 5. The cellulose nanofiber-dispersed aqueous resin reinforced material according to any one of Items 1 to 4, wherein the fibers constituting the woven fabric are at least one selected from the group consisting of carbon fibers, glass fibers, mineral fibers, artificial mineral fibers, metal fibers, synthetic fibers, regenerated fibers, plant fibers, and animal fibers.

[0014] Item 6. The cellulose nanofiber-dispersed aqueous resin reinforced material according to any one of Items 1 to 5, wherein the fibers constituting the nonwoven fabric are at least one selected from the group consisting of carbon fibers, glass fibers, mineral fibers, artificial mineral fibers, metal fibers, synthetic fibers, regenerated fibers, plant fibers, and animal fibers.

[0015] Item 7. The cellulose nanofiber-dispersed aqueous resin reinforced material according to any one of Items 1 to 6, wherein the aqueous resin is at least one selected from the group consisting of thermoplastic resins, thermosetting resins, and photocurable resins.

[0016] Item 8. The cellulose nanofiber-dispersed aqueous resin reinforced material according to any one of Items 1 to 7, further comprising a carbon fiber reinforced plastic layer on at least one side of the cellulose nanofiber-dispersed aqueous resin layer.

[0017] Item 9. A method for producing a cellulose nanofiber-dispersed aqueous resin reinforced material according to any one of items 1 to 8, (1A) a step of immersing at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood in a dispersion of the cellulose nanofibers and the aqueous resin; or (1B) A step of immersing at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood in a dispersion of the cellulose nanofibers, and then impregnating at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood with an emulsion of the aqueous resin. A manufacturing method comprising:

[0018] Item 10. The method according to Item 9, wherein a roller treatment is performed during the immersion in the dispersion in the step (1A) or during the immersion in the emulsion in the step (1B).

[0019] Item 11. The manufacturing method according to Item 9 or 10, wherein in step (1A) or (1B), the amount of the cellulose nanofibers added is 0.1 to 100 parts by mass per 100 parts by mass of the at least one substrate selected from the group consisting of woven fabrics, nonwoven fabrics, bamboo, paper, and wood.

[0020] Item 12. The method according to any one of items 9 to 11, wherein in the step (1A) or (1B), the amount of the aqueous resin added is 50 to 900 parts by mass per 100 parts by mass of at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood.

[0021] Item 13. After the step (1A) or (1B), (2) A step of heating the cellulose nanofiber-dispersed aqueous resin reinforced material obtained in step (1) to remove moisture. The method for producing a semiconductor device according to any one of items 9 to 12, comprising:

[0022] Item 14. After the step (2), (3) A step of heating and molding the obtained cellulose nanofiber-dispersed aqueous resin reinforced material under pressure. The manufacturing method according to item 13, comprising:

[0023] Item 15. The method according to item 14, wherein the molding pressure in the step (3) is 5 MPa or more. Effect of the Invention

[0024] According to the present invention, it is possible to provide a cellulose nanofiber-dispersed aqueous resin reinforced material that is lightweight and has an excellent elastic modulus without the need for hydrophobization treatment. [Brief description of the drawings]

[0025] [Figure 1] 1 shows the appearance of the test piece obtained in Example 1. [Diagram 2] The results of Test Example 1 are shown below. [Diagram 3] 1 shows the appearance of the test piece obtained in Example 2. [Figure 4] 1 shows the appearance of the test piece obtained in Example 3. [Diagram 5] The results of Test Example 3 are shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In this specification, the term "containing" is a concept that encompasses all of "comprise," "consist essentially of," and "consist only of."

[0027] In this specification, when a numerical range is indicated as "A to B," it means A or more and B or less.

[0028] 1. Cellulose nanofiber dispersed water-based resin reinforced material The cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention has a cellulose nanofiber-dispersed aqueous resin impregnated with cellulose nanofibers and an aqueous resin inside at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood.

[0029] According to this configuration, the presence of the aqueous resin allows the cellulose nanofibers to efficiently impregnate the interior of at least one substrate selected from the group consisting of woven fabrics, nonwoven fabrics, bamboo, paper, and wood, and also allows the elastic modulus to be improved by capillary action. An aqueous resin reinforced material in which cellulose nanofibers are dispersed can be produced, which is lightweight and has a high elastic modulus. Conversely, this makes it possible to reduce the amount of carbon fiber reinforced plastic that was previously required for the required elastic modulus, which can lead to resource conservation. In addition, since cellulose nanofibers are lighter than carbon fiber reinforced plastics, this can also lead to weight reduction of products.

[0030] (1-1) Cellulose nanofiber-dispersed aqueous resin layer Base material The substrate may be a woven fabric, a nonwoven fabric, bamboo, paper, wood, or the like.

[0031] The fibers constituting the woven fabric are not particularly limited, and a wide variety of organic fibers can be used, including inorganic fibers such as carbon fibers (PAN-based carbon fibers, pitch-based carbon fibers, carbon nanotubes, etc.), glass fibers (glass wool, glass fibers, etc.), mineral fibers (chrysotile asbestos, white asbestos, blue asbestos, brown asbestos, rectilinear asbestos, tremolite asbestos, and positive asbestos, etc.), artificial mineral fibers (rock wool, ceramic fibers, etc.), and metal fibers (stainless steel fibers, aluminum fibers, iron fibers, nickel fibers, and copper fibers, etc.); synthetic fibers (nylon fibers, polyester fibers, acrylic fibers, vinylon fibers, polyolefin fibers, polyethylene fibers, polypropylene fibers, and polyurethane fibers, etc.), regenerated fibers (rayon, polynosic, cupra, lyocell, acetate, etc.), plant fibers (cotton fibers, hemp fibers, flax fibers, etc.), and animal fibers (wool, silk, wild silk, mohair, cashmere, camel, llama, alpaca, vicuna, angora, and spider silk, etc.). These fibers may be used alone or in combination of two or more kinds. Among them, from the viewpoints of light weight, elastic modulus, etc., inorganic fiber fabrics are preferred, carbon fiber fabrics, glass fiber fabrics, mineral fiber fabrics, artificial mineral fiber fabrics, metal fiber fabrics, etc. are more preferred, and carbon fiber fabrics are even more preferred.

[0032] The form of the fibers may be any of continuous long fibers, short fibers obtained by cutting continuous long fibers, milled yarn obtained by pulverizing into a powder, and the like.

[0033] The thickness of the woven fabric is not particularly limited and may vary depending on the type of fiber, but may be, for example, 50 μm to 30 mm, and preferably 100 μm to 10 mm, from the viewpoints of light weight, elasticity, etc.

[0034] The basis weight of the woven fabric is not particularly limited, but is, for example, 5 to 300 g / m from the viewpoints of light weight, elasticity, etc. 2 , preferably 10 to 200 g / m 2 It can be said that:

[0035] The filament diameter of the fibers constituting the weaving yarn in the woven fabric is not particularly limited, but from the viewpoints of light weight, elastic modulus, etc., it can be, for example, 5 to 20 μm, preferably 5 to 10 μm.

[0036] The weaving yarns constituting the woven fabric may be fiber bundles. From the viewpoints of light weight, elasticity, etc., the fiber bundles preferably consist of, for example, 500 to 8000 filaments (original yarns), and more preferably 1000 to 6000 filaments (original yarns).

[0037] The fibers may be coated with known finishing agents such as flame retardants, water absorbents, water repellents, softeners, heat storage agents, ultraviolet ray shielding agents, antistatic agents, antibacterial agents, deodorants, insect repellents, mosquito repellents, phosphorescent agents, retroreflective agents, and bundling agents.

[0038] The fibers constituting the nonwoven fabric are not particularly limited, and a wide variety of organic fibers can be used, including, for example, inorganic fibers such as carbon fibers (PAN-based carbon fibers, pitch-based carbon fibers, carbon nanotubes, etc.), glass fibers (glass wool, glass fibers, etc.), mineral fibers (chrysotile asbestos, white asbestos, blue asbestos, brown asbestos, rectilinear asbestos, tremolite asbestos, and positive asbestos, etc.), artificial mineral fibers (rock wool, ceramic fibers, etc.), and metal fibers (stainless steel fibers, aluminum fibers, iron fibers, nickel fibers, and copper fibers, etc.); synthetic fibers (nylon fibers, polyester fibers, acrylic fibers, vinylon fibers, polyolefin fibers, polyethylene fibers, polypropylene fibers, and polyurethane fibers, etc.), regenerated fibers (rayon, polynosic, cupra, lyocell, acetate, etc.), plant fibers (cotton fibers, hemp fibers, flax fibers, etc.), and animal fibers (wool, silk, wild silk, mohair, cashmere, camel, llama, alpaca, vicuna, angora, and spider silk, etc.). These fibers can be used alone or in combination of two or more kinds. Among them, from the viewpoints of light weight, elastic modulus, etc., nonwoven fabrics using inorganic fibers are preferred, nonwoven fabrics using carbon fiber fabrics, glass fiber fabrics, mineral fiber fabrics, artificial mineral fiber fabrics, metal fiber fabrics, etc. are more preferred, and carbon nonwoven fabrics using carbon fiber fabrics are even more preferred.

[0039] The form of the fibers may be any of continuous long fibers, short fibers obtained by cutting continuous long fibers, milled yarn obtained by pulverizing into a powder, and the like.

[0040] The thickness of the nonwoven fabric is not particularly limited and may vary depending on the type of fiber. From the viewpoints of light weight, elasticity, etc., the thickness of the nonwoven fabric may be, for example, 50 μm to 30 mm, and preferably 100 μm to 10 mm.

[0041] The basis weight of the nonwoven fabric is not particularly limited, but is, for example, 10 to 500 g / m from the viewpoints of light weight, elasticity, etc. 2 , preferably 20 to 200 g / m 2 It can be said that:

[0042] The fibers may be coated with known finishing agents such as flame retardants, water absorbents, water repellents, softeners, heat storage agents, ultraviolet ray shielding agents, antistatic agents, antibacterial agents, deodorants, insect repellents, mosquito repellents, phosphorescent agents, retroreflective agents, and bundling agents.

[0043] The bamboo material is not particularly limited, but various bamboo materials such as Moso bamboo, Japanese bamboo, and Sasadake bamboo can be used. These bamboo materials can be used alone or in combination of two or more types. Among them, Moso bamboo is preferable from the viewpoints of light weight, elasticity, etc.

[0044] These bamboo materials can be used as is after felling, or can be crushed into small pieces, or can be processed into flat boards in the usual way.

[0045] The thickness of the bamboo material is not particularly limited and may vary depending on the type of bamboo. From the viewpoints of light weight, elasticity, etc., the thickness of the bamboo material may be, for example, 300 μm to 10 mm, preferably 500 μm to 5 mm.

[0046] The paper material is not particularly limited, and various paper materials such as Japanese paper, Western paper, processed paper, synthetic paper, and filter paper can be used. In addition, paper that has been used for other purposes, such as newsprint, printing paper (including high-quality paper), writing paper, drawing paper, wrapping paper, thin paper, and miscellaneous paper, can be used unprocessed or processed. When thin paper is used, it may be, for example, thin imitation paper, Indian paper, rice paper, glassine paper, tissue paper, toilet paper, and the like. These paper materials are preferably paper materials that have not been subjected to hydrophobic treatment such as hydrophobic coating. These paper materials can be used alone or in combination of two or more types. Among them, Japanese paper, thin paper (thin imitation paper, Indian paper, rice paper, glassine paper, tissue paper, toilet paper, and the like), and filter paper are preferable from the viewpoints of light weight, elasticity, and the like.

[0047] The thickness of the paper material is not particularly limited, and may be, for example, 10 μm to 3 mm, and preferably 100 μm to 2 mm, from the viewpoints of light weight, elasticity, etc.

[0048] The wood is not particularly limited, but various woods such as sawara, cypress, pine, cedar, red pine, larch, Ezo pine, linden pine, birch, elm, beech, poplar, Norway spruce, Norway scotch pine, Radiata pine, Douglas fir, Japanese larch, and North Pacific larch can be used. These woods can be used alone or in combination of two or more kinds. Among them, sawara and cedar are preferable from the viewpoints of light weight, elasticity, and the like.

[0049] These wood materials can be either from felled trees or from cut trees that have been crushed into small pieces.

[0050] The thickness of the wood is not particularly limited and may vary depending on the type of wood, but may be, for example, 300 μm to 10 mm, preferably 500 μm to 5 mm, from the viewpoints of light weight, elasticity, etc.

[0051] Cellulose Nanofiber The cellulose nanofibers may be any known type and are not particularly limited. The cellulose constituting the cellulose nanofibers may be any of plant-derived cellulose, animal-derived cellulose, and bacterial-derived cellulose. These may be used alone or in combination of two or more types.

[0052] The plant-derived cellulose can be selected from, for example, cellulose derived from broad-leaved trees (eucalyptus, poplar, etc.), cellulose derived from conifers (pine, fir, cedar, cypress, etc.), cellulose derived from herbaceous plants (straw, bagasse, reed, kenaf, abaca, sisal, etc.), and seed hair fibers (cotton, etc.). The raw pulp may be mechanical pulp obtained by mechanically treating wood chips, chemical pulp obtained by chemically removing non-cellulose components from wood chips, or dissolving pulp obtained by further removing non-cellulose components and refining.

[0053] Other examples include cellulose derived from animals such as sea squirts, and cellulose derived from bacteria such as nata de coco. Such cellulose does not necessarily have to be composed of pure cellulose components, and non-cellulose components may be associated with the main component cellulose. Of course, it may be composed of only pure cellulose components.

[0054] The main non-cellulose components associated with the cellulose nanofibers are not particularly limited and can be appropriately selected depending on the application. Examples include hemicellulose and lignin.

[0055] The ratio of pure cellulose components in the cellulose nanofibers may also be appropriately set depending on the application. For example, the ratio of pure cellulose components is preferably 70% by mass or more, and more preferably 80% by mass or more, in 100% by mass of the cellulose nanofibers. The upper limit of the ratio of pure cellulose components may be 100% by mass. In this specification, the cellulose ratio refers to the ratio of pure cellulose components in which β-glucose molecules are linearly polymerized through glycosidic bonds, relative to 100% by mass of the entire cellulose nanofiber.

[0056] The degree of polymerization of the pure cellulose component contained in the cellulose nanofiber can also be set appropriately depending on the application. For example, a cellulose component with a degree of polymerization of 500 or more, particularly 600 or more, can be used. There is no particular upper limit to the degree of polymerization of the cellulose component, but it can be set to, for example, 100,000.

[0057] There is no particular restriction on the crystallinity of the pure cellulose component contained in the cellulose nanofiber, and it is preferably 60% or more, and more preferably 70% or more. There is no particular restriction on the upper limit of the crystallinity of cellulose, but it can be, for example, 99%. The crystal structure of the cellulose component can be type I, type II, type III, or type IV.

[0058] There are no particular limitations on the size of the cellulose nanofibers, and when employing the production method of the present invention described below, the diameter is preferably 10 to 500 nm and the length is preferably 100 nm or more from the viewpoints of dispersibility, light weight, elastic modulus, etc. In this specification, the diameter of the cellulose nanofibers is the median diameter obtained by SEM observation of 50 or more randomly selected cellulose nanofibers.

[0059] Water-based resin The aqueous resin is not particularly limited, and for example, a thermoplastic resin, a thermosetting resin, a photocurable resin, etc. can be used.

[0060] The thermoplastic resin is not particularly limited, and examples thereof include urethane resin, polyolefin resin (polyethylene resin, polypropylene resin, etc.), polyester resin, polyamide resin, polystyrene resin, vinyl resin (polyvinyl chloride resin, polyvinyl acetate resin, polyvinylidene chloride resin, etc.), polyvinyl alcohol resin, polycarbonate resin, polyacetal resin, ethylene-vinyl acetate copolymer resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and the like.

[0061] The thermosetting resin is not particularly limited, and examples thereof include epoxy resin, phenol resin (novolac resin, etc.), acrylic resin, nylon resin, vinyl resin, polyamide resin, polyimide resin, polyamideimide resin, polystyrene resin, polycarbonate resin, polyolefin resin, polyester, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, etc.

[0062] The photocurable resin is not particularly limited, but is preferably an ultraviolet-curable resin, such as methacrylate, acrylate (particularly urethane acrylate, epoxy acrylate, and acrylic acrylate), unsaturated polyester, epoxy resin, and oxetane resin.

[0063] These aqueous resins can be used alone or in combination of two or more. As these aqueous resins, from the viewpoints of being easily impregnated into at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood, and being lightweight and having a modulus of elasticity, etc., preferred are thermoplastic resins such as urethane resins, polyolefin resins, polyester resins, and polyamide resins, preferred are thermosetting resins such as epoxy resins, phenolic resins (novolac resins, etc.), and acrylic resins, and preferred are photocurable resins such as methacrylates and acrylates. However, in the present invention, when the substrate is a woven fabric and / or nonwoven fabric, the aqueous resin is not a thermoplastic resin, that is, a thermosetting resin and / or a photocurable resin is used.

[0064] Cellulose nanofiber dispersed water-based resin layer As described above, the cellulose nanofiber-dispersed aqueous resin layer is impregnated with cellulose nanofibers and an aqueous resin in at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood. Unlike the conventional method, the cellulose nanofiber layer is not formed separately from the carbon fiber reinforced plastic layer, but the cellulose nanofiber and the thermoplastic resin are impregnated in at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood. In other words, conventionally, reinforcement was performed by providing a clear cellulose nanofiber layer, but in the present invention, a cellulose nanofiber-dispersed thermoplastic resin reinforced material that is lightweight and has excellent elasticity can be obtained without providing a clear cellulose nanofiber layer by permeating the cellulose nanofiber-dispersed thermoplastic resin into woven fabric, nonwoven fabric, bamboo, paper, wood, etc., so that it is possible to eliminate the clear interface with the CFRP layer that occurs when a clear cellulose nanofiber layer is provided, and the strength is improved.

[0065] According to the manufacturing method of the cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention described below, at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood is immersed in a dispersion of cellulose nanofibers and the aqueous resin, or at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood is immersed in a dispersion of cellulose nanofibers, and then the at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood is impregnated with an emulsion of an aqueous resin, so that it is difficult to strictly specify the content of various components in the cellulose nanofiber-dispersed aqueous resin layer. However, from the viewpoints of light weight, elastic modulus, etc., the content of cellulose nanofiber is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 20 parts by mass, per 100 parts by mass of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood.

[0066] According to the manufacturing method of the cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention described below, at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood is immersed in a dispersion of cellulose nanofibers and the aqueous resin, or at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood is immersed in a dispersion of cellulose nanofibers, and then the substrate is impregnated with an emulsion of the aqueous resin. Therefore, it is difficult to strictly specify the content of various components in the cellulose nanofiber-dispersed aqueous resin layer. However, from the viewpoint of light weight, elastic modulus, etc., the content of the aqueous resin is preferably 50 to 900 parts by mass, more preferably 100 to 300 parts by mass, per 100 parts by mass of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood.

[0067] (1-2) Carbon fiber reinforced plastic layer The cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention may be composed only of the cellulose nanofiber-dispersed aqueous resin layer, but it may also be provided with a carbon fiber reinforced plastic layer on at least one side of the cellulose nanofiber-dispersed aqueous resin layer. In the present invention, the carbon fiber reinforced plastic layer is a layer containing carbon fiber reinforced plastic.

[0068] This carbon fiber reinforced plastic can usually employ a layer in which carbon fibers are impregnated with an aqueous resin, that is, the carbon fibers are dispersed in an aqueous resin matrix.

[0069] In this case, the carbon fiber material is not particularly limited as long as it is a structure made of carbon fibers (particularly a structure made of conductive carbon fibers). Examples include a planar carbon fiber sheet, a pipe-shaped carbon fiber sheet, a wing-shaped carbon fiber sheet, an L-shaped carbon fiber sheet, and an H-shaped carbon fiber sheet. In particular, not only carbon fiber materials in which carbon fibers are arranged in a straight line, but also carbon fiber materials with complex three-dimensional shapes can be used. The fiber diameter of each carbon fiber constituting such a carbon fiber material is preferably 0.001 to 50 μm on average from the viewpoints of light weight, elastic modulus, etc. As such a carbon fiber material, a publicly known or commercially available product can be used.

[0070] The aqueous resin is not particularly limited, and for example, a thermoplastic resin, a thermosetting resin, a photocurable resin, etc. can be used.

[0071] The thermoplastic resin is not particularly limited, and examples thereof include urethane resin, polyolefin resin (polyethylene resin, polypropylene resin, etc.), polyester resin, polyamide resin, polystyrene resin, vinyl resin (polyvinyl chloride resin, polyvinyl acetate resin, polyvinylidene chloride resin, etc.), polyvinyl alcohol resin, polycarbonate resin, polyacetal resin, ethylene-vinyl acetate copolymer resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and the like.

[0072] The thermosetting resin is not particularly limited, and examples thereof include epoxy resin, phenol resin (novolac resin, etc.), acrylic resin, nylon resin, vinyl resin, polyamide resin, polyimide resin, polyamideimide resin, polystyrene resin, polycarbonate resin, polyolefin resin, polyester, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, etc.

[0073] The photocurable resin is not particularly limited, but is preferably an ultraviolet-curable resin, such as methacrylate, acrylate (particularly urethane acrylate, epoxy acrylate, and acrylic acrylate), unsaturated polyester, epoxy resin, and oxetane resin.

[0074] These aqueous resins can be used alone or in combination of two or more. As these aqueous resins, from the viewpoints of light weight, elastic modulus, etc., preferred thermoplastic resins include urethane resins, polyolefin resins, polyester resins, polyamide resins, etc., preferred thermosetting resins include epoxy resins, phenolic resins (novolac resins, etc.), acrylic resins, etc., and preferred photocurable resins include methacrylates, acrylates, etc.

[0075] The thickness of such a carbon fiber reinforced plastic layer is preferably from 10 to 500 μm, and more preferably from 50 to 200 μm, from the viewpoints of light weight, elastic modulus, and the like.

[0076] Since the carbon fiber reinforced plastic layer is a layer in which carbon fibers are impregnated with a thermoplastic resin, it is difficult to strictly specify the contents of various components. However, from the viewpoints of light weight, elastic modulus, etc., the content of the aqueous resin is preferably 50 to 900 parts by mass, more preferably 100 to 300 parts by mass, per 100 parts by mass of carbon fibers.

[0077] (1-3) Cellulose nanofiber-dispersed water-based resin reinforced material As described above, the cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention has at least a cellulose nanofiber-dispersed aqueous resin layer, and may also have a carbon fiber reinforced plastic layer as necessary.

[0078] The configuration of such a cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention is not particularly limited as long as it has a cellulose nanofiber-dispersed aqueous resin layer, and it is also possible to adopt a configuration in which at least one cellulose nanofiber-dispersed aqueous resin layer is disposed between two carbon fiber reinforced plastic layers, or a configuration in which carbon fiber reinforced plastic layers and cellulose nanofiber-dispersed aqueous resin layers are disposed alternately.

[0079] According to the present invention, a lightweight cellulose nanofiber-dispersed aqueous resin reinforced material with excellent elasticity can be obtained, which makes it possible to manufacture lightweight sports goods that could not be achieved by conventional techniques. Specifically, it is expected to be put to practical use in golf clubs (whole), tennis rackets (frames, shafts, etc.), baseball and softball bats (whole), badminton rackets (frames, shafts, etc.), shoes (soles and internal plates), flower vases, tea utensils, tea ceremony utensils (tea scoops, ladles, tea whisks, folding fans, etc.), landscaping materials, paper products, leather, etc.

[0080] For example, baseball and softball bats have thick carbon fiber layers to improve durability because the surface and carbon fiber layers break when the bat is repeatedly struck with a ball. According to the present invention, a cellulose nanofiber-dispersed aqueous resin-reinforced material with excellent elastic modulus can be obtained, making it possible to reduce the number of carbon fiber layers and reduce the weight.

[0081] In addition, although a badminton racket or the like does not break in the frame or shaft simply by hitting a shuttlecock, it is common for items other than the shuttlecock to be hit by mistake, and so it is necessary to ensure the elastic modulus of the product. In addition, high-elasticity carbon fibers are sometimes used to reduce the weight of the shaft, but in that case the elastic modulus tends to be low, so the carbon fiber layer is made thicker to increase durability. According to the present invention, a cellulose nanofiber-dispersed aqueous resin-reinforced material with excellent elastic modulus can be obtained, making it possible to reduce the number of carbon fiber layers and reduce weight.

[0082] Carbon fiber reinforced plastic materials, which have been popular in the sports market, are often used in aerospace and industrial applications. Therefore, in addition to the above-mentioned applications in sporting goods, they can also be used in the bodies and parts of automobiles and aircraft, which are currently being made lighter, and in ETC gate bars on highways.

[0083] Furthermore, in Japan, where the aging society is accelerating, maintaining the health of the elderly is a major issue. The elderly gradually lose their physical strength and muscle power, leading to a situation where it becomes increasingly difficult to move around. For clothing, shoes, braces, etc. that support the walking of the elderly, the use of the cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention makes it possible to develop lightweight and durable products, which are also useful for products for the elderly.

[0084] 2. Manufacturing method for cellulose nanofiber-dispersed water-based resin reinforced material The method for producing the cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention is not particularly limited, but may be (1A) a step of immersing at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood in a dispersion of the cellulose nanofibers and the aqueous resin; or (1B) A step of immersing at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood in a dispersion of the cellulose nanofibers, and then impregnating at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper and wood with an emulsion of the aqueous resin. Equipped with.

[0085] By adopting such a method, even if the cellulose nanofibers are not subjected to a hydrophobic treatment in step (1A) or (1B), the presence of the aqueous resin makes it possible for the cellulose nanofibers to efficiently impregnate the inside of at least one substrate selected from the group consisting of woven fabrics, nonwoven fabrics, bamboo, paper, and wood, and also makes it possible to improve the elastic modulus through capillary action.

[0086] Furthermore, by adopting such a method, it is possible to improve the elastic modulus by using cellulose nanofibers. This, in turn, makes it possible to reduce the amount of carbon fiber reinforced plastic that was previously required to achieve the desired elastic modulus, which may lead to resource conservation. Furthermore, since cellulose nanofibers are lighter than carbon fiber reinforced plastics, this may lead to weight reduction in products, and in particular to improved fuel efficiency in the case of moving objects (automobiles, aircraft, etc.).

[0087] (2-1) Process (1A) As the cellulose nanofibers, the aqueous resin, and at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood, those described above in "(1-1) Cellulose nanofiber-dispersed aqueous resin layer" can be used. The same applies to preferred aspects. As for the aqueous resin, microgel can also be used.

[0088] The dispersion of cellulose nanofibers and aqueous resin may further contain a solvent (such as monoalcohols such as methanol, ethanol, propanol, isopropanol, and butanol, Examples of polyhydric alcohols include ethylene diols such as ethylene glycol, diethylene glycol, thiodiethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol; propane diols such as 2-methyl-1,3-propanediol, 2-ethyl-1,3-propanediol, and 3-methoxy-1,2-propanediol; butane diols such as 2-butene-1,4-diol, 1,3-butanediol, and 2-methyl-1,4-butanediol; 2-methyl-2,4-pentanediol, 1,5-pentanediol, 1,4-pentanediol, and 3-methyl-1,3-pentanediol; pentanediol, 2,4-diethyl-1,5-pentanediol, and other pentanediols; hexanediols, such as 1,2-hexanediol; heptanediols, such as 1,2,6-trimethyl-1,7-heptanediol, 2,4,6-triethyl-1,7-heptanediol; octanediols, such as 3,6-dithia-1,8-octanediol; alkylene diols, such as propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol; polyols, such as glycerin, hexanetriol, thiodiglycol, trimethylolpropane; acetylene alcohol, and the like. Examples of glycol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monopropyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and ethylene glycol monophenyl ether. Examples of amines include ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, and tetramethylpropylenediamine. Other polar solvents include, for example, formamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 3-methylsulfolane, 3-sulfolene, bis(2-hydroxyethyl)sulfone, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone-5-carboxylic acid, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone, diacetone alcohol, 4-picoline, etc., as well as pigments (carbon, titanium oxide, lead silicate, aluminum phosphate, bismuth hydroxide, yttrium hydroxide, aluminum silicate, talc, etc.), functional agents (microgel, etc.), acids (acetic acid, lactic acid, formic acid, propionic acid, sulfamic acid, etc.), etc.

[0089] In this way, by immersing at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood in a dispersion of cellulose nanofibers and aqueous resin, the interior of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood can be impregnated with cellulose nanofibers and aqueous resin.

[0090] The amount (charge amount) of each component used in this case is not particularly limited, but the amount (charge amount) of the cellulose nanofiber and the aqueous resin used can be adjusted to be within the above-mentioned content range. However, according to the production method of the present invention, when at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood is immersed in a dispersion of the cellulose nanofiber and the aqueous resin, it is also possible to assume that only a part of the cellulose nanofiber and the aqueous resin is impregnated into the interior of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood, and the amount (charge amount) of the cellulose nanofiber and the aqueous resin used can be greater than the above-mentioned content. For this reason, the amount (charge amount) of the cellulose nanofiber used is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 20 parts by mass, per 100 parts by mass of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood. The amount of the thermoplastic resin used (charged amount) is preferably 50 to 900 parts by mass, and more preferably 100 to 300 parts by mass, per 100 parts by mass of the woven fabric and / or nonwoven fabric.

[0091] In the production method of the present invention, in the dispersion of cellulose nanofibers and aqueous resin, the aqueous resin (particularly the microgel of the aqueous resin) penetrates into the network structure (=mesh-like) of the cellulose nanofibers, and is uniformly dispersed in combination with the action of the polymer functional groups. When at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood is immersed in the dispersion in this state, the cellulose nanofibers, together with the aqueous resin that has penetrated into the network structure, can be impregnated into the interior of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood.

[0092] In the manufacturing method of the present invention, the temperature when immersing at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood in a dispersion of cellulose nanofibers and an aqueous resin is not limited, but from the viewpoint of easily impregnating the cellulose nanofibers and the aqueous resin into the interior of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood, a temperature of 10 to 90°C is preferred, and 20 to 70°C is more preferred.

[0093] In the manufacturing method of the present invention, the time for immersing at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood in the dispersion of cellulose nanofibers and aqueous resin is not limited, but from the viewpoint of easily impregnating the cellulose nanofibers and aqueous resin into the interior of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood, the time is preferably 0.5 to 48 hours, and more preferably 2 to 6 hours.

[0094] As described above, after carrying out step (1A), it is also possible to carry out a roller treatment. By carrying out the roller treatment, it is possible to reduce the gaps between the cellulose nanofibers and the aqueous resin, and it becomes easier to impregnate the cellulose nanofibers and the aqueous resin into at least one substrate selected from the group consisting of woven fabrics, nonwoven fabrics, bamboo, paper, and wood.

[0095] The roller treatment is not particularly limited, but can be carried out according to a conventional method.

[0096] In the method of the present invention for producing a cellulose nanofiber-dispersed aqueous resin reinforced material, the above step (1A) can be repeated multiple times (particularly 2 to 3 times), which makes it easier to further impregnate the cellulose nanofibers and aqueous resin into at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood.

[0097] (2-2) Process (1B) As the cellulose nanofibers, the aqueous resin, and at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood, those described above in "(1-1) Cellulose nanofiber-dispersed aqueous resin layer" can be used. The same applies to preferred aspects. As for the aqueous resin, microgel can also be used.

[0098] The cellulose nanofiber dispersion liquid further contains a solvent (such as monoalcohols such as methanol, ethanol, propanol, isopropanol, and butanol, Examples of polyhydric alcohols include ethylene diols such as ethylene glycol, diethylene glycol, thiodiethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol; propane diols such as 2-methyl-1,3-propanediol, 2-ethyl-1,3-propanediol, and 3-methoxy-1,2-propanediol; butane diols such as 2-butene-1,4-diol, 1,3-butanediol, and 2-methyl-1,4-butanediol; 2-methyl-2,4-pentanediol, 1,5-pentanediol, 1,4-pentanediol, and 3-methyl-1,3-pentanediol; pentanediol, 2,4-diethyl-1,5-pentanediol, and other pentanediols; hexanediols, such as 1,2-hexanediol; heptanediols, such as 1,2,6-trimethyl-1,7-heptanediol, 2,4,6-triethyl-1,7-heptanediol; octanediols, such as 3,6-dithia-1,8-octanediol; alkylene diols, such as propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol; polyols, such as glycerin, hexanetriol, thiodiglycol, trimethylolpropane; acetylene alcohol, and the like. Examples of glycol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monopropyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and ethylene glycol monophenyl ether. Examples of amines include ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, and tetramethylpropylenediamine. Other polar solvents include, for example, formamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 3-methylsulfolane, 3-sulfolene, bis(2-hydroxyethyl)sulfone, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone-5-carboxylic acid, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone, diacetone alcohol, 4-picoline, etc.), pigments (carbon, titanium oxide, lead silicate, aluminum phosphate, bismuth hydroxide, yttrium hydroxide, aluminum silicate, talc, etc.), functional agents (microgel, etc.), acids (acetic acid, lactic acid, formic acid, propionic acid, sulfamic acid, etc.), etc.

[0099] The aqueous resin emulsion further contains a solvent (such as alcohols, for example, monoalcohols such as methanol, ethanol, propanol, isopropanol, and butanol, Examples of polyhydric alcohols include ethylene diols such as ethylene glycol, diethylene glycol, thiodiethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol; propane diols such as 2-methyl-1,3-propanediol, 2-ethyl-1,3-propanediol, and 3-methoxy-1,2-propanediol; butane diols such as 2-butene-1,4-diol, 1,3-butanediol, and 2-methyl-1,4-butanediol; 2-methyl-2,4-pentanediol, 1,5-pentanediol, 1,4-pentanediol, and 3-methyl-1,3-pentanediol; pentanediol, 2,4-diethyl-1,5-pentanediol, and other pentanediols; hexanediols, such as 1,2-hexanediol; heptanediols, such as 1,2,6-trimethyl-1,7-heptanediol, 2,4,6-triethyl-1,7-heptanediol; octanediols, such as 3,6-dithia-1,8-octanediol; alkylene diols, such as propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol; polyols, such as glycerin, hexanetriol, thiodiglycol, trimethylolpropane; acetylene alcohol, and the like. Examples of glycol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monopropyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and ethylene glycol monophenyl ether. Examples of amines include ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, and tetramethylpropylenediamine. Other polar solvents include, for example, formamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 3-methylsulfolane, 3-sulfolene, bis(2-hydroxyethyl)sulfone, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone-5-carboxylic acid, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone, diacetone alcohol, 4-picoline, etc., as well as pigments (carbon, titanium oxide, lead silicate, aluminum phosphate, bismuth hydroxide, yttrium hydroxide, aluminum silicate, talc, etc.), functional agents (microgel, etc.), acids (acetic acid, lactic acid, formic acid, propionic acid, sulfamic acid, etc.), etc.

[0100] In this way, by immersing at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood in a dispersion of cellulose nanofibers, and then immersing the at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood after immersion in the dispersion of cellulose nanofibers in an emulsion of aqueous resin, it is possible to impregnate the interior of the at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood with cellulose nanofibers and aqueous resin.

[0101] The amount (charge amount) of each component used in this case is not particularly limited, but the amount (charge amount) of the cellulose nanofiber and the aqueous resin used can be adjusted to be within the above-mentioned content range. However, according to the production method of the present invention, when at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood is immersed in a dispersion of cellulose nanofibers, only a portion of the cellulose nanofibers is impregnated into the interior of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood, or when at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood after immersion in a dispersion of cellulose nanofibers is immersed in an emulsion of an aqueous resin, only a portion of the aqueous resin is impregnated into the interior of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood, and the amount (charge amount) of the cellulose nanofiber and the aqueous resin used can be greater than the above-mentioned content. For this reason, the amount of cellulose nanofiber used (charged amount) is preferably 0.1 to 100 parts by mass, and more preferably 0.5 to 20 parts by mass, per 100 parts by mass of at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood. The amount of thermoplastic resin used (charged amount) is preferably 50 to 900 parts by mass, and more preferably 100 to 300 parts by mass, per 100 parts by mass of woven fabric and / or nonwoven fabric.

[0102] In the manufacturing method of the present invention, at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood is immersed in a dispersion of cellulose nanofibers, and then the at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood after immersion in the dispersion of cellulose nanofibers is immersed in an emulsion of aqueous resin. The aqueous resin (particularly aqueous resin microgel) penetrates into the network structure (=mesh-like) of the cellulose nanofibers, and in combination with the action of the polymer functional groups, the cellulose nanofibers are uniformly dispersed, and the cellulose nanofibers, together with the aqueous resin that has penetrated into the network structure, can be impregnated into the interior of the at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood.

[0103] In the manufacturing method of the present invention, the temperature when immersing at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood in the dispersion of cellulose nanofibers and emulsion of aqueous resin is not limited, but from the viewpoint of easily impregnating the cellulose nanofibers and the aqueous resin into the interior of at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood, a temperature of 10 to 90°C is preferred, and 20 to 70°C is more preferred.

[0104] In the manufacturing method of the present invention, the time for which at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood is immersed in the dispersion of cellulose nanofibers and the emulsion of the aqueous resin is not limited, but from the viewpoint of easily impregnating the interior of the at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood with the cellulose nanofibers and the aqueous resin, the time is preferably 0.5 to 48 hours, and more preferably 2 to 6 hours.

[0105] As described above, after carrying out step (1A), it is also possible to carry out a roller treatment. By carrying out the roller treatment, it is possible to reduce the gaps between the cellulose nanofibers and the aqueous resin, and it becomes easier to impregnate the cellulose nanofibers and the aqueous resin into at least one substrate selected from the group consisting of woven fabrics, nonwoven fabrics, bamboo, paper, and wood.

[0106] The roller treatment is not particularly limited, but can be carried out according to a conventional method.

[0107] In the method of the present invention for producing a cellulose nanofiber-dispersed aqueous resin reinforced material, the above step (1A) can be repeated multiple times (particularly 2 to 3 times), which makes it easier to further impregnate the cellulose nanofibers and aqueous resin into at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood.

[0108] (2-3) Process (2) In the method for producing a cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention, after the above-mentioned step (1A) or (1B), (2) A step of heating the cellulose nanofiber-dispersed aqueous resin reinforced material obtained in step (1) to remove moisture. It can also be provided with:

[0109] This makes it possible to remove excess water present in the cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention.

[0110] In the manufacturing method of the present invention, the temperature at which the cellulose nanofiber-dispersed aqueous resin reinforced material is heated to remove moisture is not limited, but from the viewpoints of light weight, elastic modulus, etc., a temperature of 10 to 90°C is preferred, and 20 to 70°C is more preferred.

[0111] In the manufacturing method of the present invention, the time for heating the cellulose nanofiber-dispersed aqueous resin reinforced material to remove moisture is not limited, but from the standpoint of light weight, elastic modulus, etc., 0.5 to 48 hours is preferable, and 2 to 6 hours is more preferable.

[0112] (2-4) Process (3) In the method for producing a cellulose nanofiber-dispersed aqueous resin reinforced material of the present invention, after the above step (2), (3) A step of heating and molding the obtained cellulose nanofiber-dispersed aqueous resin reinforced material under pressure. It can also be provided with:

[0113] By performing pressure molding, the gaps between the cellulose nanofibers and the aqueous resin can be further reduced.

[0114] In the manufacturing method of the present invention, the temperature at which the cellulose nanofiber-dispersed aqueous resin reinforced material is heated and molded is not limited, but from the viewpoints of light weight, elastic modulus, etc., a temperature of 10 to 90°C is preferable, and 20 to 70°C is more preferable.

[0115] In the manufacturing method of the present invention, the temperature at which the cellulose nanofiber-dispersed aqueous resin reinforced material is heated and molded is not limited, but from the viewpoints of light weight, elastic modulus, etc., the temperature is preferably 0.5 to 48 hours, and more preferably 2 to 6 hours.

[0116] In the manufacturing method of the present invention, the pressure when heating and molding the cellulose nanofiber-dispersed aqueous resin reinforced material is not limited, but from the viewpoints of light weight, elastic modulus, etc., it is preferably 5 MPa or more, more preferably 10 to 60 MPa, and even more preferably 20 to 30 MPa. EXAMPLES

[0117] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0118] In the following Examples and Comparative Examples, a water-based ultraviolet-curable resin emulsion, Elecoat UC-4H (manufactured by Shimizu Corporation; solid content 60% by mass), was used as the photocurable resin.

[0119] In the following examples and comparative examples, cellulose nanofibers (manufactured by Daio Paper Co., Ltd.; average fiber diameter 900 nm, average fiber length 2 μm) were used.

[0120] [Example 1: Bamboo] After drying the bamboo material (10 g of Moso bamboo, manufactured by Takano Bamboo Works Co., Ltd.) in a tray, 5.5 g (solid content 3.3 g) of Elecoat UC-4H (manufactured by Shimizu Co., Ltd.), which is a water-based ultraviolet-curing resin emulsion, and 110 g (solid content 3.3 g) of cellulose nanofiber mixed solution (manufactured by Daio Paper Co., Ltd.) were mixed and applied at 20°C to impregnate the paper material with cellulose nanofiber and water-based ultraviolet-curing resin. After that, ultraviolet light was irradiated for 5 minutes using a UV irradiation device (I-Grantage mini, manufactured by I-Graphics Co., Ltd.). The appearance of the test piece obtained in Example 1 is shown in Figure 1.

[0121] [Comparative Example 1: Bamboo] A bamboo material (Moso bamboo manufactured by Takano Bamboo Co., Ltd.; 10 g) was used as it was as a test piece for Comparative Example 1.

[0122] [Comparative Example 2: Bamboo] Instead of using the cellulose nanofiber mixture (manufactured by Daio Paper Co., Ltd.), 5.5 g (solid content 3.3 g) of Elecoat UC-4H (manufactured by Shimizu Co., Ltd.), which is a water-based ultraviolet-curable resin emulsion, was applied. The rest was the same as in Example 1, and a test piece for Comparative Example 2 was obtained.

[0123] [Test example 1: Three-point bending test of bamboo] The elastic modulus (rigidity) and maximum bending stress were evaluated in accordance with JIS K7171:2016 "Plastics - Determination of bending properties."

[0124] The results are shown in Figure 2. As a result, in Comparative Example 1, in which the bamboo material was used as is, the elastic modulus (rigidity) was 965 × 10 3N / mm 2 The maximum bending stress was 38 MPa, whereas the elastic modulus (rigidity) was 1060 × 10 3 N / mm 2 In contrast, by adding and impregnating cellulose nanofibers and a water-based UV-curable resin as in Example 1, the elastic modulus (rigidity) increased to 1160×10 3 N / mm 2 The maximum bending stress was 40 MPa, and it was possible to improve both the elastic modulus and the maximum bending stress.

[0125] [Example 2: Paper] After drying the paper material (Toyo Roshi Co., Ltd. circular quantitative filter paper No. 7; 0.1 g) in a tray, 5.5 g (solid content 3.3 g) of Elecoat UC-4H (Shimizu Co., Ltd.), a water-based UV-curable resin emulsion, and 110 g (solid content 3.3 g) of cellulose nanofiber mixture (Daioh Paper Co., Ltd.) were mixed and applied at 20°C to impregnate the paper material with cellulose nanofiber and water-based UV-curable resin. After that, the paper was irradiated with UV light for 5 minutes using a UV irradiation device (I-Grantage mini, I-Graphics Co., Ltd.).

[0126] [Comparative Example 3: Paper] A paper material (circular quantitative filter paper No. 7; 0.1 g, manufactured by Toyo Roshi Kaisha, Ltd.) was used as it was as a test piece for Comparative Example 3.

[0127] [Comparative Example 4: Paper] Instead of using the cellulose nanofiber mixture (manufactured by Daio Paper Co., Ltd.), 5.5 g (solid content 3.3 g) of Elecoat UC-4H (manufactured by Shimizu Co., Ltd.), which is a water-based ultraviolet-curable resin emulsion, was applied. The rest was the same as in Example 1, and a test piece for Comparative Example 4 was obtained.

[0128] [Test Example 2: Maximum stress] The sample was attached to a tabletop tensile / compression testing machine, Force Tester MCT-2150, manufactured by A&D Co., Ltd., and the test was performed at a test speed of 10 mm / s.

[0129] As a result, in Comparative Example 3, in which the paper material was used as is, the maximum stress was 8.3 MPa, whereas when an aqueous ultraviolet-curable resin was added as in Comparative Example 4, the maximum stress increased to 28 MPa. However, by adding and impregnating cellulose nanofibers and an aqueous ultraviolet-curable resin as in Example 2, it was possible to further increase the maximum stress to 33 MPa.

[0130] [Example 3: Wood] After drying wood (5 g) in a tray, 5.5 g (solid content 3.3 g) of Elecoat UC-4H (manufactured by Shimizu Corporation), which is a water-based ultraviolet-curing resin emulsion, was mixed with 110 g (solid content 3.3 g) of cellulose nanofiber mixed solution (manufactured by Daio Paper Corporation) at 20°C and applied to impregnate the wood with cellulose nanofiber and water-based ultraviolet-curing resin. After that, ultraviolet light was irradiated for 5 minutes using a UV irradiation device (I-Grantage mini manufactured by I-Graphics Co., Ltd.). The appearance of the test piece obtained in Example 3 is shown in FIG. 4.

[0131] [Comparative Example 5: Wood] The wood (Sawara; 5 g) was used as it was as a test piece for Comparative Example 5.

[0132] [Comparative Example 6: Wood] Instead of using the cellulose nanofiber mixture (manufactured by Daio Paper Co., Ltd.), 5.5 g (solid content 3.3 g) of Elecoat UC-4H (manufactured by Shimizu Co., Ltd.), which is a water-based ultraviolet-curable resin emulsion, was applied. The rest was the same as in Example 3, and a test piece for Comparative Example 6 was obtained.

[0133] [Test Example 3: Flexural modulus] The flexural modulus (rigidity) and maximum bending stress were evaluated in accordance with JIS K7171:2016 "Plastics - Determination of bending properties."

[0134] The results are shown in Figure 5. As a result, in Comparative Example 3 in which wood was used as is, the flexural modulus was 4.3 GPa and the maximum flexural stress was 29 MPa, whereas when an aqueous ultraviolet-curable resin was added as in Comparative Example 4, the flexural modulus (rigidity) was 5.0 GPa and the maximum flexural stress was 38 MPa, making it possible to improve the flexural modulus and maximum flexural stress, and by adding and impregnating cellulose nanofibers and an aqueous ultraviolet-curable resin as in Example 3, the flexural modulus was 5.4 GPa and the maximum flexural stress was 48 MPa, making it possible to further improve the flexural modulus and maximum flexural stress.

Claims

1. A cellulose nanofiber-dispersed aqueous resin reinforced material having a cellulose nanofiber-dispersed aqueous resin layer impregnated with cellulose nanofibers and an aqueous resin inside at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood (however, when the substrate is a textile and / or nonwoven fabric, the aqueous resin is not a thermoplastic resin).

2. The cellulose nanofiber-dispersed aqueous resin reinforced material according to claim 1, wherein the bamboo material is at least one selected from the group consisting of Moso bamboo, Japanese bamboo, and Sasa bamboo.

3. The cellulose nanofiber-dispersed aqueous resin reinforced material according to claim 1, wherein the paper material is at least one selected from the group consisting of Japanese paper, Western paper, processed paper, synthetic paper, and filter paper.

4. The cellulose nanofiber-dispersed aqueous resin reinforced material according to claim 1, wherein the wood is at least one selected from the group consisting of sawara, cypress, pine, cedar, red pine, larch, Ezo pine, linden pine, birch, elm, beech, poplar, Norway spruce, Norway scotch pine, Radiata pine, Douglas fir, Japanese larch, and North Pacific larch.

5. The cellulose nanofiber-dispersed aqueous resin reinforced material according to claim 1, wherein the fibers constituting the woven fabric are at least one selected from the group consisting of carbon fibers, glass fibers, mineral fibers, artificial mineral fibers, metal fibers, synthetic fibers, regenerated fibers, plant fibers and animal fibers.

6. The cellulose nanofiber-dispersed aqueous resin reinforced material according to claim 1, wherein the fibers constituting the nonwoven fabric are at least one selected from the group consisting of carbon fibers, glass fibers, mineral fibers, artificial mineral fibers, metal fibers, synthetic fibers, regenerated fibers, plant fibers and animal fibers.

7. The cellulose nanofiber-dispersed aqueous resin reinforced material according to claim 1 , wherein the aqueous resin is at least one selected from the group consisting of thermoplastic resins, thermosetting resins, and photocurable resins.

8. The cellulose nanofiber-dispersed aqueous resin reinforced material according to claim 1 , further comprising a carbon fiber reinforced plastic layer on at least one side of the cellulose nanofiber-dispersed aqueous resin layer.

9. A method for producing a cellulose nanofiber-dispersed aqueous resin reinforced material according to any one of claims 1 to 8, (1A) a step of immersing at least one substrate selected from the group consisting of woven fabrics, nonwoven fabrics, bamboo, paper, and wood into a dispersion of the cellulose nanofibers and the aqueous resin; or (1B) A step of immersing at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood in a dispersion of the cellulose nanofibers, and then impregnating at least one substrate selected from the group consisting of textiles, nonwoven fabrics, bamboo, paper, and wood in an emulsion of the aqueous resin. A manufacturing method comprising:

10. The method according to claim 9 , wherein the immersion in the dispersion in the step (1A) or the immersion in the emulsion in the step (1B) is performed with a roller.

11. The manufacturing method according to claim 9, wherein in step (1A) or (1B), the amount of the cellulose nanofibers added is 0.1 to 100 parts by mass per 100 parts by mass of the at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood.

12. The manufacturing method according to claim 9, wherein in the step (1A) or (1B), the amount of the aqueous resin added is 50 to 900 parts by mass per 100 parts by mass of the at least one substrate selected from the group consisting of woven fabric, nonwoven fabric, bamboo, paper, and wood.

13. After the step (1A) or (1B), (2) A step of heating the cellulose nanofiber-dispersed aqueous resin reinforced material obtained in step (1) to remove moisture. The method of claim 9 , comprising:

14. After the step (2), (3) A step of heating and molding the obtained cellulose nanofiber-dispersed aqueous resin reinforced material under pressure. The method of claim 13, comprising:

15. The method according to claim 14, wherein the molding pressure in the step (3) is 5 MPa or more.

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