Fiber molded body and application thereof

Abstract

One problem addressed by the present invention is to provide: a fiber molded body having sufficient strength; and a composite material using the same. Further, another problem addressed by the present invention is to provide: a fiber molded body in which fiber dropout at the time of cutting is small or substantially absent; and a composite material using the same.　As constituent components of this fiber molded body, a main fiber material and a fibrous binder as a binding component are included. A heat / moisture-adhesive binder is used as the fibrous binder. The content ratio of the main fiber material and the fibrous binder in the fiber molded body can be 1-20 parts by weight of the fibrous binder per 100 parts by weight of the main fiber material. Also, the water dissolution temperature of the fibrous binder is preferably 30-95°C.

Description

Fiber moldings and their applications

[0001] The present disclosure relates to a fiber molded article and its applications. More specifically, the present disclosure relates to a fiber molded article, a material such as a fibrous binder to be mixed with the fiber molded article, a fiber-reinforced resin molded article using the fiber molded article, and methods for manufacturing these.

[0002] Fiber reinforced plastics (FRP) are reinforced plastic materials that have a matrix of epoxy resin, phenolic resin, or the like, to which fiber materials such as glass fiber or carbon fiber are compounded to improve various functions. Carbon fiber, in particular, is a lightweight material that has excellent strength and elastic modulus, and carbon fiber reinforced plastics (CFRP) using carbon fiber are used in an extremely wide range of fields, such as automobile components, ship components, aircraft components, spacecraft components, drone components, civil engineering and construction materials, sporting goods, and components for electronic devices and electrical appliances such as personal computers.

[0003] Generally, FRP is produced by impregnating a sheet of fiber material with a resin component that serves as the matrix. While a wide range of technological developments have been made to improve the performance of FRP, one of the important factors in producing composite materials using such fiber materials is that the fiber molding itself must have sufficient strength before being impregnated with the matrix.

[0004] A typical example of a sheet-like fiber material used in FRP is nonwoven fabric. Various methods for producing nonwoven fabric from fiber materials have already been developed, not limited to the field of FRP. Furthermore, research and development has been conducted on the production of nonwoven fabrics intended for use in FRP.

[0005] For example, in a fiber-reinforced plastic molding that uses a thermoplastic resin as a binder for carbon fibers, if the thermoplastic resin melts at high temperatures such as during thermal melting, the fixation of the intertwining points between the carbon fibers is impaired, resulting in the collapse of the three-dimensional structure of the carbon fibers, making the carbon fibers more likely to be oriented in a specific direction, and reducing strength. To solve this problem, a method has been disclosed in which a papermaking sheet before resin impregnation is subjected to a papermaking process using a mixed dispersion of carbon fibers and water-swollen filtrated fibers (for example, Patent Document 1).

[0006] Furthermore, when inorganic fibers such as carbon fibers, glass fibers, and metal fibers are processed into nonwoven fabrics by a wet papermaking method, the inorganic fibers are hydrophobic and therefore have poor dispersibility in water, making it difficult to obtain an inorganic fiber sheet with good formation.To solve this problem, a technique using a dispersant containing a specific surfactant or resin has been disclosed (for example, Patent Document 2).

[0007] In recent years, there has been a global consensus calling for the promotion of sustainable development, and as the use of composite materials composed of fibers such as carbon fiber and a matrix material increases as described above, there is also a demand for the development of methods for their reuse.

[0008] International Publication No. 2014 / 021366 Japanese Patent Application Laid-Open No. 2017-57511

[0009] As mentioned above, one way to utilize the excellent properties of the fibers incorporated into FRP is to ensure that the strength of the fiber molding itself is excellent before it is impregnated with the matrix. However, when fiber components such as carbon fibers are separated from molded products such as CFRP for reuse, the recycled carbon fibers obtained by separation are significantly different from virgin fibers and often end up being fragmented and short fibers compared to virgin fibers. Even when attempts are made to reprocess recycled carbon fibers into fiber molding sheets, it has been difficult to process them into sheets in the first place, or even if they can be processed into sheets, it has been difficult to obtain the strength, durability, and other performance required for FRP materials.

[0010] Therefore, one approach to producing fiber molding sheets using recycled fibers is to increase the amount of binder. However, from the perspective of producing FRP with desired performance, it has been desired to minimize the amount of binder in order to make the most of the properties of the main fiber material. Furthermore, there has been a need for a binder suitable for producing moldings using various types of fiber materials, not just carbon fiber.

[0011] Furthermore, carbon fiber molded articles in particular tend to lose some of their fibers when they are cut, so if stray carbon fibers accidentally or unavoidably find their way into an electronic device, there is a concern that they may cause a short circuit.

[0012] In view of the above circumstances, one of the problems to be solved is to provide a fiber molding having sufficient strength and a composite material using the same.

[0013] Another object of the present invention is to provide a fiber molding that causes little or no fiber shedding during cutting, and a composite material using the same.

[0014] Another problem to be solved is to provide a fiber molding having sufficient strength using recycled carbon fibers and a composite material using the same, and more preferably to provide a fiber molding having little or no fiber shedding when cutting and a composite material using the same.

[0015] Another problem to be solved is to provide a fiber molding having sufficient strength and a composite material using the same, using various types of fiber materials, and more preferably to provide a fiber molding and a composite material using the same, in which little or no fiber falls off when cutting.

[0016] The present inventors have conducted extensive research and found that by using a heat-and-moisture adhesive fibrous binder, it is possible to form a fiber molding that has a predetermined strength and does not fall off when cut, which is suitable for the production of FRP, etc. The present disclosure is based on this finding.

[0017] The invention presented in this disclosure can be understood in multiple aspects and may include, for example, the following embodied aspects as means for solving problems. Note that in this disclosure, the invention presented in this disclosure is also simply referred to as "the present invention" either as a comprehensive concept or according to each individual aspect.

[0018] [1] A fiber molded product comprising a main fiber material and a moisture-heat-bonding fibrous binder, wherein the content ratio of the main fiber material to the moisture-heat-bonding fibrous binder is 1 to 20 parts by weight per 100 parts by weight of the main fiber material, and the moisture-heat-bonding fibrous binder has a dissolution temperature in water of 30 to 95°C. [2] The fiber molded product according to [1] above, wherein the moisture-heat-bonding fibrous binder is a polyvinyl alcohol-based moisture-heat-bonding fibrous binder. [3] The fiber molded product according to [1] or [2] above, wherein the main fiber material is one or more fibers selected from the group consisting of carbon fiber, glass fiber, metal fiber, natural fiber, cellulose-based fiber, regenerated fiber, semi-synthetic fiber, and synthetic fiber. [4] The fiber molded article according to any one of [1] to [3] above, wherein the main fiber material is one or more fibers selected from the group consisting of carbon fiber, glass fiber, and PET-based fiber. [5] The fiber molded article according to any one of [1] to [4] above, wherein the main fiber material is virgin carbon fiber, recycled carbon fiber, a mixture thereof, or a mixture of virgin carbon fiber, recycled carbon fiber, or a mixture thereof with one or more fibers selected from the group consisting of glass fiber, metal fiber, natural fiber, cellulose-based fiber, recycled fiber, semi-synthetic fiber, and synthetic fiber. [6] The fiber molded article according to any one of [1] to [5] above, wherein the moisture content of the wet-bonding fibrous binder is 0.5 to 25%. [7] The fiber molded article according to [6] above, wherein the wet-bonding fibrous binder is a polyvinyl alcohol-based moist heat-bonding fibrous binder. [8] The fiber molded article according to [6] or [7] above, wherein the main fiber material is one or more types selected from the group consisting of carbon fiber, glass fiber, metal fiber, natural fiber, cellulose-based fiber, regenerated fiber, semi-synthetic fiber, and synthetic fiber. [9] The fiber molded article according to any one of [6] to [8] above, wherein the main fiber material is one or more types selected from the group consisting of carbon fiber, glass fiber, and PET-based fiber.

[10] The fiber molding according to any one of [6] to [9] above, wherein the main fiber material is a first-use carbon fiber, a recycled carbon fiber, a mixed fiber thereof, or a mixed fiber of a first-use carbon fiber, a recycled carbon fiber, or a mixed fiber thereof with one or more fibers selected from the group consisting of glass fiber, metal fiber, natural fiber, cellulosic fiber, regenerated fiber, semi-synthetic fiber, and synthetic fiber.

[11] The fiber molded product according to any one of [1] to

[10] above, further comprising fibrillated fibers, the fibrillated fibers having a acrylic ratio of 1.25 to 3.00, and the content ratio of the main fiber material to the heat-and-moisture bonding fibrous binder and fibrillated fibers is 1 to 20 parts by weight per 100 parts by weight of the main fiber material.

[12] The fiber molded product according to

[11] above, wherein the weight ratio of the heat-and-moisture bonding fibrous binder to the fibrillated fibers in the fiber molded product is 5:95 to 95:5.

[13] The fiber molded product according to

[11] or

[12] above, wherein the fineness ratio of the fibrillated fibers is 95% or less.

[14] A fiber-reinforced resin molding comprising the fiber molding according to any one of [1] to

[13] above and a resin component impregnated into the fiber molding.

[0019] According to one or more aspects of the invention presented in the present disclosure, a fiber molding having sufficient strength can be provided.

[0020] According to one or more aspects of the invention presented in the present disclosure, it is possible to provide a fiber molding in which little or no fibers fall off during cutting, and a composite material using the same.

[0021] Furthermore, according to one or more aspects of the invention presented in this disclosure, it is possible to provide a fiber molding having sufficient strength and a composite material using the same using recycled carbon fibers, and more preferably to provide a fiber molding having little or no fiber shedding during cutting.

[0022] Furthermore, according to one or more aspects of the invention presented in this disclosure, it is possible to provide fiber moldings with sufficient strength and composite materials using the same using various types of fiber materials, and more preferably, to provide fiber moldings with little or no fiber shedding during cutting.

[0023] Furthermore, according to one or more aspects of the invention presented in the present disclosure, various excellent composite materials can be provided using the above-described fiber molded article.

[0024] Figure 1 shows sample images of the surface and cut portion (edge) of the sheet of Example S5(1). Figure 2 shows sample images of the surface and cut portion (edge) of the sheet of Comparative Example S3(1).

[0025] This disclosure has been filed as an international application under the Patent Cooperation Treaty, and the original language of the application is Japanese. It is intended that this disclosure will be translated into the languages ​​required by each designated and elected state upon entry into those states. In this disclosure, unless otherwise specified, Japanese nouns may be singular or plural, depending on the context or the full text of this disclosure. Furthermore, when translated into a language such as English that distinguishes between countable and uncountable nouns, and between singular and plural countable nouns, unless otherwise specified, the singular designation includes the plural, and the plural designation includes the singular, depending on the context or the full text of this disclosure.

[0026] Hereinafter, embodiments of the present invention will be described. In this disclosure, the term "one embodiment" with respect to the present invention refers to any one embodiment in describing the present invention in detail, unless otherwise specified, and does not deny or limit the existence of other or multiple embodiments. As will be described below, the present invention may include multiple embodiments within its scope. Furthermore, multiple embodiments may also be provided as modified forms, for example, by various combinations of the components (or technical features) shown in this disclosure. Furthermore, in this disclosure, when the term "embodiment" is simply used, it includes one or multiple embodiments unless otherwise specified.

[0027] In this disclosure, unless otherwise specified, the expression "AA to BB" in relation to a numerical range means "AA or more and BB or less" (where "AA" and "BB" represent arbitrary numerical values). Furthermore, unless otherwise specified, the units of the lower and upper limits are the same as the units immediately following the latter (i.e., "BB" here). Furthermore, in this disclosure, the combination of the lower and upper limits of a numerical range can be arbitrarily selected from the group of lower or upper limit values ​​exemplified as preferred numerical values, etc. Furthermore, the expression "X and / or Y" means both X and Y, or either one of them.

[0028] 1. Fibrous Binder The fibrous binder of the present disclosure can be suitably used as a binder for binding together the main fiber material that constitutes the body of a fibrous molded article, which will be described in detail below.

[0029] A preferred example of the fibrous binder is a moist heat-adhesive fibrous binder, such as a moist heat-adhesive polyvinyl alcohol fibrous binder, an ethylene-vinyl alcohol copolymer fibrous binder, or a polyethylene-co-acrylic acid fibrous binder.

[0030] The water dissolution temperature of the heat-and-moisture adhesive fibrous binder is preferably 30 to 95° C. More specifically, it is as follows.

[0031] The upper limit of the water dissolution temperature of the fibrous binder is preferably 95° C. or lower. Having the water dissolution temperature within this range contributes to the formation of a fibrous molded product having sufficient strength at an appropriate drying temperature. From the viewpoint of further pursuing sufficient strength of the fibrous molded product at an appropriate drying temperature, the upper limit of the water dissolution temperature of the moist heat-bonding type fibrous binder may be more preferably 90° C. or lower, and even more preferably 85, 80, 75, 70, or 65° C. or lower.

[0032] The lower limit of the water dissolution temperature of the fibrous binder may be usually, preferably, 30, 35, 40, 45, 50, or 55° C. or higher, from the viewpoint of further pursuing a fibrous molded article having sufficient strength.

[0033] In the present disclosure, the "water dissolution temperature" of the fibrous binder can be determined by a general method employed in the technical fields of organic fibers, organic binders, etc., and is a physical property index generally used in product catalogs or specifications of organic fibers, organic binders, etc.

[0034] <Average fiber length of fibrous binder> The average fiber length of the fibrous binder may be preferably 1.0 to 10.0 mm. Having the average fiber length within this range contributes to the formation of a fibrous molded article with sufficient strength. In order to further improve the strength of the fibrous molded article, more preferable lower and upper limits may be as follows.

[0035] The lower limit of the average fiber length of the fibrous binder is more preferably 1.5 mm or more, and even more preferably 2.0 or 2.5 mm or more.

[0036] The upper limit of the average fiber length of the fibrous binder may more preferably be 9.0, 8.0, 7.0, 6.0, or 5.0 mm or less, and even more preferably be 4.0 mm or less.

[0037] <Average fiber diameter of fibrous binder> The average fiber diameter of the fibrous binder may be preferably 2.0 to 40.0 μm. Having the average fiber diameter within this range contributes to the formation of a fibrous molded article with sufficient strength. From the viewpoint of further pursuing the strength of the fibrous molded article, more preferable lower and upper limits are as follows.

[0038] The lower limit of the average fiber diameter of the fibrous binder is more preferably 3.0 μm or more, and even more preferably 4.0, 5.0, 6.0, or 7.0 μm or more.

[0039] The upper limit of the average fiber diameter of the fibrous binder is more preferably 35.0 μm or less, and even more preferably 30.0, 25.0, 20.0, 15.0, 12.0, or 10.0 μm or less.

[0040] <Moisture Content of Fibrous Binder> The moisture content of the fibrous binder may preferably be 0.5 to 60.0%. A moisture content within this range contributes to the formation of a fibrous molded article with sufficient strength. From the viewpoint of further pursuing the strength of the fibrous molded article, more preferable lower and upper limits are as follows.

[0041] The lower limit of the moisture content of the fibrous binder is more preferably 1.0% or more, and even more preferably 1.5, 2.0, or 2.5% or more.

[0042] The upper limit of the moisture content of the fibrous binder is more preferably 55.0% or less, and even more preferably 50.0, 45.0, 40.0, 35.0, 30.0, 25.0, 20.0, 15.0, or 10.0% or less.

[0043] <Glauert's salt deposition rate of polyvinyl alcohol-based fibrous binder> The glauber's salt deposition rate of the polyvinyl alcohol-based fibrous binder can be preferably 2.0 to 50.0%. Having the glauber's salt deposition rate within this range contributes to the formation of a fibrous molded product with sufficient strength. From the viewpoint of further pursuing the strength of the fibrous molded product, more preferable lower and upper limits are as follows.

[0044] The lower limit of the Glauber's salt adhesion rate of the polyvinyl alcohol-based fibrous binder is more preferably 3.0% or more, and even more preferably 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0% or more.

[0045] The upper limit of the Glauber's salt adhesion rate of the polyvinyl alcohol-based fibrous binder is more preferably 55.0% or less, and even more preferably 50.0, 45.0, 40.0, 35.0, 30.0, 25.0, 20.0, 15.0, or 10.0% or less.

[0046] 2. Fiber Molded Product The fiber molded product of the present disclosure is a fiber molded product containing a main fiber material and a binder component as constituent materials. In other words, the fiber molded product of the present disclosure can be said to be a product molded by mixing a binder component with a main fiber material and binding them together. The binder component can be suitably the above-mentioned fibrous binder. That is, an example of an embodiment of the fiber molded product of the present disclosure is a fiber molded product containing a main fiber material and a fibrous binder. The shape of the molded product is not particularly limited, but preferred shapes include a sheet or plate.

[0047] The main fiber material is the main material of the molded body. The content ratio of the main fiber material to the fiber binder is preferably 1 to 20 parts by weight of the fibrous binder per 100 parts by weight of the main fiber material.

[0048] In general, in FRP, which is obtained by impregnating a nonwoven fabric (fiber molding) as a base material with a resin component that serves as a base material (matrix) and then curing it, there has been a strong demand for the amount of binder component in the nonwoven fabric to be as small as possible. This is presumably because, from the perspective of making the most of the inherent properties of the main fiber material, binders have been considered an unnecessary component. However, it is difficult to produce a fiber molding such as a nonwoven fabric that has a reasonable strength using only the main fiber material without using any binder, and so until now, it has been unavoidable to use as little binder as possible when producing fiber moldings such as nonwoven fabrics.

[0049] In contrast, the fiber molding of the present disclosure uses the above-mentioned specific fibrous binder, which allows the fiber molding to have sufficient strength. Moreover, it has been found that such a fibrous molding has excellent strength and the like even when further processed into a form such as FRP.

[0050] As described above, the amount of the fibrous binder per 100 parts by weight of the main fiber material can be any value between 1 and 20 parts by weight. More specifically, the amount of the fibrous binder per 100 parts by weight of the main fiber material can be 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 part by weight.

[0051] As a numerical range, the upper limit of the amount of the fibrous binder is more preferably 18 parts by weight or less, and even more preferably 15, 13, or 10 parts by weight or less, per 100 parts by weight of the main fiber material. On the other hand, the lower limit of the amount of the fibrous binder is more preferably 2, 3, or 4 parts by weight or more, per 100 parts by weight of the main fiber material.

[0052] The main fiber material and the fibrous binder can be mixed by adding the main fiber material and the fibrous binder to a liquid medium such as water and stirring the mixture. When mixing the main fiber material and the fibrous binder, other additives such as a dispersant and a thickener may also be added.

[0053] The use of a dispersant can impart hydrophilic properties to the hydrophobic main fiber material and reduce secondary aggregation by promoting repulsion between fibers. Examples of dispersants include polyoxyalkylene monophenyl ether, polyether-based urethane resin, and polyoxyethylene polyoxypropylene stearyl ether.

[0054] The amount of the dispersant to be added is preferably 1 to 20 parts by weight, more preferably 3 to 10 parts by weight, per 100 parts by weight of the main fiber material.

[0055] The use of a thickener can also provide viscosity to the slurry, reducing secondary aggregation of the hydrophobic main fiber material. Examples of thickeners include polyethylene oxide and sodium polyacrylate.

[0056] The blending amount of the viscosity agent may be preferably 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, per 100 parts by weight of the main fiber material.

[0057] <Main Fiber Material> The main fiber material is not particularly limited as long as it can be formed into woven fabrics, knitted fabrics, nonwoven fabrics, etc. The main fiber material may be inorganic or organic. Examples of inorganic fibers include carbon fiber, glass fiber, and metal fiber. Examples of organic fibers include "natural fibers" such as cotton, hemp, and animal hair, "synthetic fibers" made from petroleum, wood-derived cellulose fibers, and "semi-synthetic fibers" or "regenerated fibers" made from natural materials through various processes. Examples of "synthetic fibers" include polyamide fibers, polyester fibers, polyurethane fibers, polyvinyl alcohol fibers, pitch fibers, polyacrylonitrile (PAN) fibers, phenolic fibers, polyphenylene sulfide fibers, polyvinyl chloride fibers, polypropylene fibers, polyethylene fibers, and polystyrene fibers. Examples of "regenerated fibers" obtained from natural materials include rayon, cupra, and lyocell.

[0058] Preferred examples of the main fiber material include carbon fiber, glass fiber, metal fiber, cellulose-based fiber, recycled fiber, semi-synthetic fiber, and synthetic fiber. More specifically, examples of inorganic fibers include carbon fiber, glass fiber, and metal fiber, while examples of organic fibers include cellulose-based fiber, pitch-based fiber, PAN-based fiber, phenol-based fiber, PET-based fiber, aramid-based fiber, and polyphenylene sulfide-based fiber. Among these, more preferred examples of the main fiber material include carbon fiber, glass fiber, PET-based fiber, and aramid-based fiber, and even more preferred examples of the main fiber material include carbon fiber. Examples of carbon fiber include rayon-based carbon fiber, pitch-based carbon fiber, PAN-based carbon fiber, and phenol-based carbon fiber, and activated carbon fiber may also be used. One type of main fiber material may be used alone, or two or more types may be used.

[0059] The carbon fiber may be a first-time carbon fiber, a recycled carbon fiber (recycled carbon fiber), or a mixture of these. In this disclosure, the term "first-time" (or unused) with respect to carbon fiber is used as the opposite term to the term "recycled" and refers not to a "recycled" (or recycled) fiber, but to a brand-new fiber that is used for the first time after production as fiber, such as a so-called virgin fiber. In this disclosure, "recycled" (or recycled) carbon fiber refers to a fiber recovered through a recycling process using in-process scraps generated during the production process and used CFRP products (products that were once used for some purpose as carbon fiber) that are discarded as waste materials as raw materials for recycling. Furthermore, in this disclosure, with regard to carbon fiber, "recycled carbon fiber" is also referred to as "recycled carbon fiber," "recovered carbon fiber," or, as is commonly called, "regenerated carbon fiber" (in English, it is also commonly called Recycled Carbon Fiber (abbreviation: rCF)).

[0060] <Average fiber length of main fiber material> The average fiber length of the main fiber material may be preferably 1 to 100 mm. Having the average fiber length within this range contributes to the formation of a fibrous molded product with sufficient strength. In order to further enhance the strength of the fibrous molded product, more preferable lower and upper limits may be as follows.

[0061] The lower limit of the average fiber length of the main fiber material may be more preferably 2, 3, or 4 mm or more, and even more preferably 5 mm or more.

[0062] The upper limit of the average fiber length of the main fiber material may more preferably be 80, 60, 50, 40, or 30 mm or less, and even more preferably be 20 mm or less.

[0063] <Average fiber diameter of main fiber material> The average fiber diameter of the main fiber material may be preferably 1.0 to 50.0 μm. Having the average fiber diameter within this range contributes to the formation of a fibrous molded product with sufficient strength. From the viewpoint of further pursuing the strength of the fibrous molded product, more preferable lower and upper limits are as follows.

[0064] The lower limit of the average fiber diameter of the main fiber material may be more preferably 2.0, 3.0, 4.0, or 5.0 μm or more, and even more preferably 6.0 μm or more.

[0065] The upper limit of the average fiber diameter of the main fiber material may be more preferably 40.0, 30.0, 20.0, or 15.0 μm or less, and even more preferably 10.0 μm or less.

[0066] In one preferred embodiment of the present disclosure, recycled carbon fiber (rCF), which is carbon fiber separated and recovered from FRP or the like, can be suitably used. Such recycled carbon fiber is typically shorter than the original fiber length before being processed into FRP or the like, and has a rough surface, which tends to result in insufficient strength when processed into nonwoven fabrics. However, by using the fibrous binder of the present disclosure, nonwoven fabrics using such recycled carbon fiber as a fiber material can be made to have sufficient strength. In another preferred embodiment, recycled carbon fiber and virgin carbon fiber (unused carbon fiber) may be mixed to form the main fiber material.

[0067] The method for forming the fiber into a fibrous molded article such as a nonwoven fabric is not particularly limited, and a conventional method can be used. For example, in a method for manufacturing a nonwoven fabric, a fiber sheet can be obtained by a wet method using a main fiber material cut to an appropriate length as a raw material.

[0068] A binder component such as a fibrous binder is used to bind the main fiber material and form a molded product with a predetermined overall shape and strength. As described above, the molding of a fiber molded product can be performed by a conventional method. For example, a sheet-shaped fiber molded product can be obtained as follows. First, the main fiber material and various components, such as the binder component, are added to a solvent such as water, and the mixture is stirred and mixed to prepare a slurry. The resulting slurry is then formed into a sheet, and dehydrated as appropriate. After dehydration, the moisture content is further adjusted, and the product is further dried using a drying device, etc., as necessary, to obtain a sheet-shaped fiber molded product.

[0069] When the semi-finished product formed using the slurry while dehydrating is further heated and dried in a drying device or the like, the temperature may be set appropriately depending on various conditions such as the main fiber material, binding component, or the type, shape, or size of the final fiber molded product. For example, the drying temperature is preferably 80 to 250°C, more preferably 90 to 240°C, 100 to 230°C, 120 to 220°C, 140 to 210°C, 160 to 200°C, even more preferably 170 to 190°C, and more specifically, around 180°C.

[0070] In addition to the above-mentioned fibrous binder and main fiber material, the molded article of the present disclosure may also contain, for example, fibrillated fibers as a binding component. "Fibrillation" refers to the process of causing fibers to fluff or splinter by friction or beating. In other words, it can also be said that small fibers (i.e., fibrils) are fluffed from the fiber body by friction or beating. In the present disclosure, "fibrillated fibers" refer to fibers that have been fibrillated and have small fibers (fibrils) fluffed on the surface.

[0071] Examples of fibrillated fibers include natural cellulose fibers, chemically modified cellulose fibers, and regenerated cellulose fibers. Examples of natural cellulose fibers include wood pulp, such as softwood pulp and hardwood pulp, and herbaceous pulp, such as straw pulp, bamboo pulp, linter pulp, hemp pulp, and kenaf pulp. Examples of chemically modified cellulose fibers include oxidized, etherified, cationized, or esterified cellulose fibers. Examples of regenerated cellulose fibers include rayon, cupra, and lyocell. A wide variety of synthetic fibers can also be used. Examples of such fibrillated fibers include acrylic fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, nylon fibers, and aramid fibers.

[0072] That is, fibrillated fibers can be obtained by subjecting fibers to treatment such as friction or beating using, for example, a single disc refiner (SDR), a double disc refiner (DDR), a beater, a mixer, a mill, a grinding device, etc. to loosen and fluff the surface of the fibers. Alternatively, a suspension or slurry of fibers may be prepared and then treated at high speed and high pressure using a homogenizer.

[0073] The fibrillated fiber preferably satisfies at least one of the following indices relating to properties, etc., or any two or more of these indices.

[0074] <Freeness> In the present disclosure, "freeness" is an index indicating the fibrillation of fibers, and is determined by measuring the amount of water removed when a test sample (for example, fibrillated fibers in the present disclosure) is made into a slurry and the water is drained all at once through a specified filter. More specifically, the freeness value in the present disclosure can be determined by the measurement method used in the following examples, etc. The higher the freeness value, the easier it is to remove water and the less fuzz there is. Conversely, the lower the value, the more difficult it is to remove water and the more fuzz there is. Note that freeness is also referred to as beating degree or freeness.

[0075] The freeness of the fibrillated fiber may be preferably 0 to 100 ml when measured according to the specific test method carried out in the examples, etc., which will be described in detail below. A freeness within this range contributes to the formation of a fibrous molded product with sufficient strength.

[0076] From the viewpoint of further improving the strength of the fibrous molded article, the lower limit of the freeness of the fibrillated fiber is theoretically most preferably 0, but may be practically 5 ml or more.

[0077] On the other hand, the upper limit of the freeness of the fibrillated fibers may more preferably be 50 ml or less, and even more preferably 40, 30, or 20 ml or less.

[0078] <Average fiber length of fibrillated fibers> The average fiber length of the fibrillated fibers may be preferably 0.30 to 2.50 mm. Having the average fiber length within this range contributes to the formation of a fibrous molded product with sufficient strength. In order to further improve the strength of the fibrous molded product, more preferable lower and upper limits may be as follows.

[0079] The lower limit of the average fiber length of the fibrillated fibers may be more preferably 0.35 mm or more, and even more preferably 0.40, 0.45, or 0.50 mm or more.

[0080] The upper limit of the average fiber length of the fibrillated fibers may more preferably be 2.00, 1.75, or 1.50 mm or less, and even more preferably be 1.25 mm or less.

[0081] <Average fiber diameter of fibrillated fibers> The average fiber diameter of the fibrillated fibers may be preferably 10.0 to 40.0 μm. Having the average fiber diameter within this range contributes to the formation of a fibrous molded article with sufficient strength. From the viewpoint of further pursuing the strength of the fibrous molded article, more preferable lower and upper limits are as follows.

[0082] The lower limit of the average fiber diameter of the fibrillated fibers is more preferably 15.0 μm or more, and even more preferably 20.0 μm or more.

[0083] The upper limit of the average fiber diameter of the fibrillated fibers is more preferably 38.0 μm or less, and even more preferably 35.0 μm or less.

[0084] <Cryl Ratio of Fibrillated Fibers> In this disclosure, the "cryl ratio" refers to the ratio of the reduction in the ultraviolet and infrared regions of the transmitted light when light is incident on a fibrillated fiber slurry. Fibrils, which are formed by beating and have a diameter approximately 1 / 100 of the fiber, scatter and absorb primarily ultraviolet light, whether attached to the fiber or floating away. Therefore, the transmitted light in the ultraviolet region is reduced relative to the incident light, and the amount of reduction correlates with the total surface area of ​​the fibrils. On the other hand, non-fibril fibers primarily scatter and absorb infrared light, and therefore the transmitted light in the infrared region is reduced relative to the incident light, and the amount of reduction correlates with the total surface area of ​​the non-fibril fibers. Therefore, the cryl ratio serves as an index of the degree of fibrillation of fibrillated fibers. The cryl ratio value in this disclosure can be determined by the measurement method used in the following examples, etc.

[0085] The fibrillated fiber preferably has a cryl ratio of 1.25 to 3.00. A cryl ratio within this range contributes to the formation of a fibrous molded article with sufficient strength.

[0086] From the viewpoint of further improving the strength of the fibrous molding, the lower limit of the Cryl ratio is more preferably 1.30 or more, and even more preferably 1.35 or more.

[0087] The upper limit of the cryl ratio may preferably be 2.80, 2.60, or 2.40 or less.

[0088] <Fineness ratio (%) of fibrillated fibers> In the present disclosure, the fineness ratio is an index showing the proportion of fine fibers having a fiber length of less than 0.2 mm. The value of the fineness ratio in the present disclosure can be determined by the measurement method used in the following examples, etc. In the process of fibrillating the fibers, the fibers are excessively ground and finely divided to a fiber length of less than 0.2 mm, which is considered to have a low contribution to the binding effect of the fibrous molded product.

[0089] The fineness of the fibrillated fibers is preferably 10 to 95%. More specifically, the fineness is as follows.

[0090] The upper limit of the fineness ratio of the fibrillated fiber is preferably 95% or less. A fineness ratio within this range contributes to the formation of a fibrous molded product with sufficient strength. From the viewpoint of further pursuing the strength of the fibrous molded product, the upper limit of the fineness ratio of the fibrillated fiber is more preferably 90% or less, and even more preferably 85, 80, 75, or 70% or less.

[0091] The lower limit of the fineness ratio of the fibrillated fibers may be set arbitrarily from the viewpoint of further improving the strength of the fibrous molded article, but is usually preferably 10, 20, 30, or 40% or more.

[0092] When a heat-and-moisture adhesive fibrous binder and fibrillated fibers are used as the binding components, the content of the heat-and-moisture adhesive fibrous binder and fibrillated fibers per 100 parts by weight of the main fiber material can be any value between 1 and 20 parts by weight. More specifically, the amount of the fibrous binder can be 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 part by weight per 100 parts by weight of the main fiber material.

[0093] As a numerical range, the upper limit of the content of the heat-and-moisture bonding fibrous binder and fibrillated fiber is more preferably 18 parts by weight or less, and even more preferably 15, 13, or 10 parts by weight or less, per 100 parts by weight of the main fiber material. On the other hand, the lower limit of the content of the heat-and-moisture bonding fibrous binder and fibrillated fiber is more preferably 2, 3, or 4 parts by weight or more, per 100 parts by weight of the main fiber material.

[0094] The weight ratio of the fibrous binder to the fibrillated fiber is 5:95 to 95:5. From the viewpoint of further improving the strength of the fibrous molded article, the weight ratio of the fibrous binder to the fibrillated fiber is more preferably 10:90 to 90:10, still more preferably 15:85 to 85:15, 20:80 to 80:20, 25:75 to 75:25, 30:70 to 70:30, 35:65 to 65:35, or 40:60 to 60:40.

[0095] In addition to the above-described fibrous binder and main fiber material or fibrillated fiber, the molded article of the present disclosure may also use other types of binders and other materials. Examples of such materials include painters used in papermaking, such as starch, SBR, polyvinyl alcohol-based aqueous solutions, unsaturated polyester-based aqueous solutions, and acrylic-based aqueous solutions. Other examples include composite fibers such as core-sheath fibers, parallel fibers, and radially split fibers. Specifically, combinations of polypropylene (core) and polyethylene (sheath), polypropylene (core) and ethylene vinyl alcohol (sheath), high-melting-point polyester (core) and low-melting-point polyester (sheath), and high-melting-point polyester (core) and polyethylene (sheath) may be used. Fully melted fibers composed solely of polyethylene or polypropylene may also be used.

[0096] A preferred embodiment of the fiber molded article of the present disclosure may be a sheet-shaped molded article. In the case of a sheet-shaped molded article, the basis weight thereof is preferably 20 to 200 g / m 2 It is possible.

[0097] Setting the lower limit of the basis weight to the above-mentioned preferred value or more contributes to preventing a shortage of tensile strength of the sheet-form molded article. From the viewpoint of preventing a shortage of tensile strength of the sheet-form molded article, the lower limit of the basis weight is more preferably 30 g / m 2 , more preferably 40 g / m 2 It is possible.

[0098] On the other hand, by setting the upper limit of the basis weight to the above-mentioned preferred value or less, it is possible to easily remove moisture and dry the sheet in the manufacturing process. From the viewpoint of ease of drying treatment, the upper limit of the basis weight is more preferably 190, 180, or 170 g / m 2 , more preferably 160 or 150 g / m 2 It is possible.

[0099] The density of the fiber molding of the present disclosure is preferably 0.05 to 0.20 g / cm 3 It is possible.

[0100] By setting the lower limit of the density to the above-mentioned preferred value or more, it is possible to improve the composite balance with the resin when processing into FRP, etc. From the viewpoint of such composite balance with the resin, the lower limit of the density is more preferably 0.06 or 0.07 g / cm 3 or more, more preferably 0.08 or 0.09 g / cm 3 It could be more than that.

[0101] On the other hand, by setting the upper limit of the density to the above-mentioned preferred value or less, resin impregnation can be more easily performed when processing into FRP, etc. From the viewpoint of resin impregnation, the upper limit of the density is more preferably 0.19 or 0.18 g / cm. 3 , more preferably 0.17 or 0.16 g / cm 3 It is possible.

[0102] The tensile strength of the fiber molded article of the present disclosure can be adjusted to a good value. The tensile strength of the fiber molded article of the present disclosure can be adjusted appropriately according to needs. There are several possible means for adjusting the tensile strength, and it can be adjusted, for example, by the amount of fibrous binder added.

[0103] When measured according to the specific test method (using a test piece 15 mm wide and 150 mm long) performed in the examples described below, the tensile strength of the fiber molding of the present disclosure can be adjusted to, for example, at least 0.06 or 0.07 kN / mm or more. Even higher tensile strengths can be achieved, for example, to 0.10, 0.15, 0.19, 0.21, or 0.22 kN / mm or more, or even 0.23, 0.25, 0.30, or 0.40 kN / mm or more.

[0104] 3. Applications of Fiber Molded Products (3.1) The fiber molded products of the present disclosure can be used in a wide range of applications. For example, various FRPs can be obtained by impregnating a sheet-shaped fiber molded product of the present disclosure (also referred to as a fiber molded product sheet) with a resin matrix and curing the impregnated product. Examples of FRPs include glass fiber reinforced plastics, carbon fiber reinforced plastics, boron fiber reinforced plastics, and aramid fiber reinforced plastics.

[0105] (3.2) When activated carbon fiber is used as the main material of the fiber molding of the present disclosure, it can be used as an adsorbent for liquid and gas phases. The adsorbent may be suitable for applications such as water purification and chemical filters for semiconductor manufacturing clean rooms.

[0106] The present invention will be described in more detail below with reference to examples, but the technical scope (or technical reach) of the invention presented in this disclosure is not limited to the following examples. The following measurement methods, calculation methods, evaluation methods, and other methods can be used to determine numerical values ​​when the invention presented in this disclosure is specified using numerical values.

[0107] <FBA1 (fibrous binder)> A polyvinyl alcohol-based binder synthetic fiber (moisture-heat adhesive type), product name: SPG056-11 (manufactured by Kuraray Co., Ltd.), having a fineness of 0.58 dtex, a diameter equivalent to a perfect circle of 8 μm, a dissolution temperature in water of 62° C., a sodium sulfate adhesion rate of 29.0%, a fiber length of 3 mm, and a water content (by weight) of 3.5% was prepared and diluted with water in advance to obtain a 0.5% (w / w) slurry.

[0108] <FBA2 (fibrous binder)> A polyvinyl alcohol-based binder synthetic fiber (moisture-heat adhesive type), product name: VPB041 (manufactured by Kuraray Co., Ltd.), having a fineness of 0.44 dtex, a diameter equivalent to a perfect circle of 6 μm, a water dissolution temperature of 80° C., a fiber length of 3 mm, and a water content (by weight) of 5.4% was prepared and diluted with water in advance to obtain a 0.5% (w / w) slurry.

[0109] <FBA3 (fibrous binder)> A polyvinyl alcohol-based binder synthetic fiber (moisture-heat adhesive type), product name: VPB107-1 (manufactured by Kuraray Co., Ltd.), having a fineness of 1.17 dtex, a diameter equivalent to a perfect circle of 11 μm, a dissolution temperature in water of 74° C., a sodium sulfate adhesion rate of 7.5%, a fiber length of 3 mm, and a water content (by weight) of 45.9% was prepared and diluted with water in advance to obtain a 0.5% (w / w) slurry.

[0110] <FBA4 (fibrous binder)> A polyvinyl alcohol-based binder synthetic fiber (moisture-heat adhesive type), product name: VPB053 (manufactured by Kuraray Co., Ltd.), having a fineness of 0.6 dtex, a diameter equivalent to a perfect circle of 8 μm, a water dissolution temperature of 100° C., a fiber length of 3 mm, and a water content (by weight) of 30.5% was prepared and diluted with water in advance to obtain a 0.5% (w / w) slurry.

[0111] <FBB1 (Fibrillated Fiber)> (1) Preparation of Pulp Slurry 300 g of unbeaten LBKP (bleached hardwood pulp) (manufactured by Nippon Paper Industries Co., Ltd.) was defibrated to obtain a 3.0% (W / V) slurry. (2) Fibrillation The obtained pulp slurry was fibrillated by 11 passes through a single-disc refiner, followed by dilution with water to obtain a 0.5% (W / W) slurry with a freeness of 32 ml, an average fiber length of 0.78 mm, an average fiber diameter of 20.8 μm, a cryl ratio of 1.37, and a fineness ratio of 48.4%.

[0112] <FBB2 (Fibrillated Fiber)> (1) Preparation of Pulp Slurry 300 g of unbeaten NBKP (bleached softwood pulp) (manufactured by Nippon Paper Industries Co., Ltd.) was defibrated to obtain a 3.0% (W / V) slurry. (2) Fibrillation The obtained pulp slurry was fibrillated by circulating it through a single-disc refiner for four passes, and then diluted with water to obtain a 0.5% (W / W) slurry with a freeness of 15 ml, an average fiber length of 1.03 mm, an average fiber diameter of 28.8 μm, a crill ratio of 1.63, and a fineness ratio of 49.9%.

[0113] <FBB3 (Fibrillated Fiber)> (1) Preparation of Pulp Slurry A 3.0% (W / V) slurry was obtained in the same manner as in FBB2 (1). (2) Fibrillation The obtained pulp slurry was fibrillated by circulating it through a single-disc refiner for 10 passes, and then diluted with water to obtain a 0.5% (W / W) slurry with a freeness of 0 ml, an average fiber length of 0.56 mm, an average fiber diameter of 25.6 μm, a cryl ratio of 2.14, and a fineness ratio of 59.3%.

[0114] <FBB4 (Fibrillated Fiber)> (1) Preparation of Chemically Modified Pulp 40 kg of unbeaten NBKP (manufactured by Nippon Paper Industries Co., Ltd.) was added to 4000 L of an aqueous solution containing 312 g (0.05 mmol per 1 g of bone-dry cellulose) of TEMPO (manufactured by Sigma-Aldrich) and 4112 g (1.0 mmol per 1 g of bone-dry cellulose) of sodium bromide, and the mixture was stirred. An aqueous solution of sodium hypochlorite was then added to adjust the sodium hypochlorite concentration to 5.5 mmol / g, and the oxidation reaction was initiated at room temperature. To address the pH drop during the reaction, 3 M aqueous sodium hydroxide solution was added sequentially to adjust the pH to 10. The reaction was terminated when the sodium hypochlorite was consumed and the pH in the system no longer changed. Hydrochloric acid was added to the reaction mixture to adjust the pH to 2, and the pulp was thoroughly washed with water by repeatedly dehydrating and diluting with water. The pulp was then dehydrated until the pulp solids concentration reached 20% by weight, yielding a chemically modified pulp with a carboxyl group content of 1.4 mmol / g.

[0115] (2) Fibrillation The resulting chemically modified pulp was dispersed in water, and sodium hydroxide was added and stirred to obtain a 1.1% (W / V) slurry at pH 7.7. 4,300 kg of the resulting slurry was fibrillated by 20 passes through a monoflow double-disc refiner at a circulation rate of 80%. The resulting slurry was then diluted with water to obtain a 0.5% (W / W) slurry with a freeness of 0 ml, an average fiber length of 0.29 mm, an average fiber diameter of 30.3 μm, a cryl ratio of 3.33, and a fineness ratio of 99.8%.

[0116] <FBB5 (Fibrillated Fiber)> (1) Preparation of Pulp Slurry A 3.0% (W / V) slurry was prepared in the same manner as in FBB1 (1). (2) Dilution The obtained pulp slurry was diluted with water to obtain a 0.5% (W / W) slurry with a freeness of 620 ml, an average fiber length of 0.94 mm, an average fiber diameter of 19.8 μm, a cryl ratio of 0.83, and a fine ratio of 30.7%.

[0117] <FBB6 (Fibrillated Fiber)> (1) Preparation of Pulp Slurry A 3.0% (W / V) slurry was obtained in the same manner as in FBB1 (1). (2) Fibrillation The obtained pulp slurry was fibrillated by circulating it through a single-disc refiner for five passes, and then diluted with water to obtain a 0.5% (W / W) slurry with a freeness of 78 ml, an average fiber length of 0.83 mm, an average fiber diameter of 20.2 μm, a cryl ratio of 1.22, and a fineness ratio of 42.6%.

[0118] <FBB7 (Fibrillated Fiber)> (1) Preparation of Pulp Slurry A 3.0% (W / V) slurry was prepared in the same manner as in FBB2 (1). (2) Dilution The resulting pulp slurry was diluted with water to obtain a 0.5% (W / W) slurry with a freeness of 650 ml, an average fiber length of 2.11 mm, an average fiber diameter of 28.0 μm, a cryl ratio of 0.98, and a fine ratio of 13.5%.

[0119] <FBB8 (Fibrillated Fiber)> (1) Preparation of Pulp Slurry A 3.0% (W / V) slurry was obtained in the same manner as in FBB2 (1). (2) Fibrillation The obtained pulp slurry was fibrillated by two passes through a single-disc refiner, followed by dilution with water to obtain a 0.5% (W / W) slurry with a freeness of 362 ml, an average fiber length of 1.80 mm, an average fiber diameter of 27.6 μm, a cryl ratio of 1.20, and a fineness ratio of 25.7%.

[0120] Example S1 (Fiber Molded Product Sheet) Blend (1): Recycled carbon fiber 95.5% (W / W), Binding component: Fibrous binder 4.5% (W / W) At room temperature, using a commercial mixer with a power of 2800 W and a capacity of 3.9 L, 0.08 g of a dispersant (aqueous solution of polyether-based polyurethane resin, manufactured by Meisei Chemical Industry Co., Ltd., model number Pulset HA) and 140 g of a viscosity agent (a 0.1% (w / w) aqueous solution of polyethylene oxide, manufactured by Meisei Chemical Industry Co., Ltd., model number Alcox SK) were added to 700 ml of water and stirred uniformly. After that, 1.36 g of recycled carbon fiber (manufactured by Carbon Fiber Recycle Kogyo Co., Ltd., 9 mm sieved product obtained by secondary heating of Toray Industries, Inc. model number T800SC offcuts, average fiber diameter 7 μm, average fiber length 10 mm, moisture content 1.4%) and 12.66 g of fibrous binder FBA1 were added as the main fiber material, and the mixture was stirred at a rotation speed of 15,000 rpm for 6 minutes to obtain a slurry. This slurry was hand-sheeted using a round (16 mm diameter) hand-sheeting machine (manufactured by Tozai Seiki Co., Ltd.), and then coated in accordance with JIS P8222:2015 (five sets of rolling with a coach roll) to adjust the moisture content of the fiber molding to about 70%. The fiber molding was then dried in a dryer at 180°C for 10 minutes to obtain a fiber molding sheet of Example S1(1).

[0121] Blend (2): Carbon fiber 95.5% (W / W), binding component: Fibrous binder 4.5% (W / W) A fibre sheet of Example S1(2) was obtained in the same manner as Blend (1), except that 1.36 g of carbon fibre (manufactured by Toray Industries, Inc., model number T700SC-12K-50C, average fibre diameter 7 μm, average fibre length 12 mm, moisture content 1.0%) was used as the main fibre material.

[0122] Blend (3): Glass fiber 95.5% (W / W), binding component: Fibrous binder 4.5% (W / W) A fibre sheet of Example S1(3) was obtained in the same manner as Blend (1), except that 1.43 g of glass fiber (manufactured by PFG Fiber Glass Corporation, model number E225, average fibre diameter 7 μm, average fibre length 5 mm, water content 6.0%) was used as the main fibre material.

[0123] Blend (4): PET fiber 95.5% (w / w), binding component: fibrous binder 4.5% (w / w) A fiber molded body sheet of Example S1(4) was obtained in the same manner as Blend (1), except that 1.43 g of PET fiber (manufactured by Teijin Limited, model number TA04N SD 0.6x5, average fiber diameter 7 μm, average fiber length 5 mm, moisture content 5.9%) was used as the main fiber material.

[0124] Example S2 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Example S2(1), Example S2(2), Example S2(3), and Example S2(4)) were obtained in the same manner as Examples S1(1) to S1(4), except that the fibrous binder FBA2 was used. Blend (1): Recycled carbon fiber 95.5% (W / W), binding component: fibrous binder 4.5% (W / W); Blend (2): Carbon fiber 95.5% (W / W), binding component: fibrous binder 4.5% (W / W); Blend (3): Glass fiber 95.5% (W / W), binding component: fibrous binder 4.5% (W / W); Blend (4): PET fiber 95.5% (W / W), binding component: fibrous binder 4.5% (W / W).

[0125] Example S3 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Example S3(1), Example S3(2), Example S3(3), and Example S3(4)) were obtained in the same manner as Examples S1(1) to S1(4), except that the fibrous binder FBA3 was used. Blend (1): Recycled carbon fiber 95.5% (w / w), binder component: fibrous binder 4.5% (w / w); Blend (2): Carbon fiber 95.5% (w / w), binder component: fibrous binder 4.5% (w / w); Blend (3): Glass fiber 95.5% (w / w), binder component: fibrous binder 4.5% (w / w); Blend (4): PET fiber 95.5% (w / w), binder component: fibrous binder 4.5% (w / w).

[0126] Example S4 (Fiber Molded Product Sheet) Blend (1): Recycled carbon fiber 95.5% (W / W), Binding component: Fibrous binder 1.5% (W / W), Fibrillated fiber 3.0% (W / W) At room temperature, using a commercial mixer with a power of 2800 W and a capacity of 3.9 L, 0.08 g of a dispersant (aqueous solution of polyether-based polyurethane resin, manufactured by Meisei Chemical Industry Co., Ltd., model number Pulset HA) and 140 g of a viscosity agent (a 0.1% (w / w) aqueous solution of polyethylene oxide, manufactured by Meisei Chemical Industry Co., Ltd., model number Alcox SK) were added to 700 ml of water and stirred uniformly. After that, 1.36 g of recycled carbon fiber (manufactured by Carbon Fiber Recycle Kogyo Co., Ltd., 9 mm sieved product obtained by secondary heating of Toray Industries, Inc. model number T800SC scraps, average fiber diameter 7 μm, average fiber length 10 mm, moisture content 1.4%) was added as the main fiber material, 4.22 g of fibrous binder FBA1, and 8.44 g of fibrillated fiber FBB1 were added, and the mixture was stirred at a rotation speed of 15,000 rpm for 6 minutes to obtain a slurry. This slurry was hand-sheeted using a round (16 mm diameter) hand-sheeting machine (manufactured by Tozai Seiki Co., Ltd.), and then coated in accordance with JIS P8222:2015 (five sets of rolling with a coach roll) to adjust the moisture content of the fiber molding to about 70%. The fiber molding was then dried in a dryer at 180°C for 10 minutes to obtain a fiber molding sheet of Example S4(1).

[0127] Blend (2): Carbon fiber 95.5% (W / W), binding components: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) A fiber molded sheet of Example S4(2) was obtained in the same manner as Blend (1), except that 1.36 g of carbon fiber (manufactured by Toray Industries, Inc., model number T700SC-12K-50C, average fiber diameter 7 μm, average fiber length 12 mm, moisture content 1.0%) was used as the main fiber material.

[0128] Blend (3): Glass fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) A fiber molded sheet of Example S4(3) was obtained in the same manner as Blend (1), except that 1.43 g of glass fiber (manufactured by PFG Fiber Glass Corporation, model number E225, average fiber diameter 7 μm, average fiber length 5 mm, moisture content 6.0%) was used as the main fiber material.

[0129] Blend (4): PET fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) A fiber molded sheet of Example S4(4) was obtained in the same manner as Blend (1), except that 1.43 g of PET fiber (manufactured by Teijin Limited, model number TA04N SD 0.6x5, average fiber diameter 7 μm, average fiber length 5 mm, moisture content 5.9%) was used as the main fiber material.

[0130] Example S5 (Fiber Molded Product Sheet) Four types of fiber molded product sheets, Example S5(1), Example S5(2), Example S5(3), and Example S5(4), were obtained in the same manner as in Examples S4(1) to S1(4), except that FBB2 fibrillated fibers were used. Blend (1): Recycled carbon fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) Blend (2): Carbon fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) Blend (3): Glass fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) Blend (4): PET fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) Note that the surface and edge (cut portion) of the sheet of Example S5(1) were photographed to obtain image samples (see Figure 1).

[0131] Example S6 (Fiber Molded Product Sheet) Four types of fiber molded product sheets, Example S6(1), Example S6(2), Example S6(3), and Example S6(4), were obtained in the same manner as Examples S4(1) to S1(4), except that the fibrillated fiber FBB3 was used. Blend (1): Recycled carbon fiber 95.5% (W / W), binding component: fibrous binder fiber 1.5% (W / W), fibrillated fiber 3.0% (W / W) Blend (2): Carbon fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) Blend (3): Glass fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W) Blend (4): PET fiber 95.5% (W / W), binding component: fibrous binder 1.5% (W / W), fibrillated fiber 3.0% (W / W)

[0132] Comparative Example S1 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Comparative Example S1(1), Comparative Example S1(2), Comparative Example S1(3), and Comparative Example S1(4)) were obtained in the same manner as in Examples S1(1) to S1(4), except that the fibrous binder FBA4 was used. Blend (1): Recycled carbon fiber 95.5% (W / W), Binder: Fibrous binder fiber 4.5% (W / W) Blend (2): Carbon fiber 95.5% (W / W), Binder: Fibrous binder 4.5% (W / W) Blend (3): Glass fiber 95.5% (W / W), Binder: Fibrous binder 4.5% (W / W) Blend (4): PET fiber 95.5% (W / W), Binder: Fibrous binder 4.5% (W / W)

[0133] Comparative Example S2 (Fiber Molded Sheet) Blend (1): Recycled carbon fiber 95.5% (W / W), Binding component: Fibrillated fiber 4.5% (W / W) At room temperature, using a commercial mixer with a power of 2800 W and a capacity of 3.9 L, 0.08 g of a dispersant (aqueous solution of polyether-based polyurethane resin, manufactured by Meisei Chemical Industry Co., Ltd., model number Pulset HA) and 140 g of a viscosity agent (a 0.1% (w / w) aqueous solution of polyethylene oxide, manufactured by Meisei Chemical Industry Co., Ltd., model number Alcox SK) were added to 700 ml of water and stirred uniformly. After that, 1.36 g of recycled carbon fiber (manufactured by Carbon Fiber Recycle Kogyo Co., Ltd., 9 mm sieved product obtained by secondary heating of Toray Industries, Inc. model number T800SC offcuts, average fiber diameter 7 μm, average fiber length 10 mm, moisture content 1.4%) and 12.66 g of FBB1 fibrillated fiber were added as the main fiber material, and the mixture was stirred at a rotation speed of 15,000 rpm for 6 minutes to obtain a slurry. This slurry was hand-sheeted using a round (16 mm diameter) hand-sheeting machine (manufactured by Tozai Seiki Co., Ltd.), and then coated in accordance with JIS P8222:2015 (five sets of rolling with a coach roll) to adjust the moisture content of the fiber molding to about 70%. The fiber molding was then dried in a dryer at 180°C for 10 minutes to obtain a fiber molding sheet of Comparative Example S2(1).

[0134] Blend (2): Carbon fiber 95.5% (W / W), binding component: Fibrillated fiber 4.5% (W / W) A fiber molded sheet of Comparative Example S2(2) was obtained in the same manner as Blend (1), except that 1.36 g of carbon fiber (manufactured by Toray Industries, Inc., model number T700SC-12K-50C, average fiber diameter 7 μm, average fiber length 12 mm, moisture content 1.0%) was used as the main fiber material.

[0135] Blend (3): Glass fiber 95.5% (W / W), binding component: Fibrillated fiber 4.5% (W / W) A fiber molded sheet of Comparative Example S2(3) was obtained in the same manner as Blend (1), except that 1.43 g of glass fiber (manufactured by PFG Fiber Glass Corporation, model number E225, average fiber diameter 7 μm, average fiber length 5 mm, moisture content 6.0%) was used as the main fiber material.

[0136] Blend (4): PET fiber 95.5% (W / W), binding component: fibrillated fiber 4.5% (W / W) A fiber sheet of Comparative Example S2(4) was obtained in the same manner as Blend (1), except that 1.43 g of PET fiber (manufactured by Teijin Limited, model number TA04N SD 0.6x5, average fiber diameter 7 μm, average fiber length 5 mm, moisture content 5.9%) was used as the main fiber material.

[0137] <Comparative Example S3 (Fiber Molded Product Sheet)> Four types of fiber molded product sheets: Comparative Example S3(1), Comparative Example S3(2), Comparative Example S3(3), and Comparative Example S3(4) were obtained in the same manner as Comparative Examples S2(1) to S2(4), except that the fibrillated fibers of FBB2 were used. Blend (1): Recycled carbon fiber 95.5% (W / W), binding component: fibrillated fiber 4.5% (W / W) Blend (2): Carbon fiber 95.5% (W / W), binding component: fibrillated fiber 4.5% (W / W) Blend (3): Recycled carbon fiber 95.5% (W / W), binding component: fibrillated fiber 4.5% (W / W) Blend (4): Carbon fiber 95.5% (W / W), binding component: fibrillated fiber 4.5% (W / W) Note that for the sheet of Comparative Example S3(1), the surface and edge (cut portion) were photographed to obtain image samples (see Figure 2).

[0138] Comparative Example S4 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Comparative Example S4(1), Comparative Example S4(2), Comparative Example S4(3), and Comparative Example S4(4)) were obtained in the same manner as Comparative Examples S2(1) to S2(4), except that the fibrillated fiber FBB3 was used. Blend (1): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (2): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (3): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (4): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W)

[0139] Comparative Example S5 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Comparative Example S5(1), Comparative Example S5(2), Comparative Example S5(3), and Comparative Example S5(4)) were obtained in the same manner as Comparative Examples S2(1) to S2(4), except that the fibrillated fiber FBB4 was used. Blend (1): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (2): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (3): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (4): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W)

[0140] Comparative Example S6 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Comparative Example S6(1), Comparative Example S6(2), Comparative Example S6(3), and Comparative Example S6(4)) were obtained in the same manner as Comparative Examples S2(1) to S2(4), except that the fibrillated fiber FBB5 was used. Blend (1): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (2): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (3): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (4): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W)

[0141] Comparative Example S7 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Comparative Example S7(1), Comparative Example S7(2), Comparative Example S7(3), and Comparative Example S7(4)) were obtained in the same manner as Comparative Examples S2(1) to S2(4), except that the fibrillated fiber FBB6 was used. Blend (1): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (2): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (3): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (4): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W)

[0142] Comparative Example S8 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Comparative Examples S8(1), S8(2), S8(3), and S8(4)) were obtained in the same manner as Comparative Examples S2(1) to S2(4), except that FBB7 fibrillated fiber was used. Blend (1): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (2): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (3): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (4): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W)

[0143] Comparative Example S9 (Fiber Molded Product Sheet) Four types of fiber molded product sheets (Comparative Example S9(1), Comparative Example S9(2), Comparative Example S9(3), and Comparative Example S9(4)) were obtained in the same manner as Comparative Examples S2(1) to S2(4), except that the fibrillated fiber FBB8 was used. Blend (1): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (2): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (3): Recycled carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W) Blend (4): Carbon fiber 95.5% (W / W), Binder component: Fibrillated fiber 4.5% (W / W)

[0144] The shapes, physical properties, and other properties of the fibrous binder, main fiber material, fibrillated fiber, and fiber molded article, as well as various performance-related items, were measured and evaluated by the methods described below. Note that the values ​​and evaluations of the shapes, physical properties, and other properties and performances described in this disclosure can be determined by the following measurement and evaluation methods.

[0145] <Freeness of Fibrillated Fiber> The freeness of the fibrillated fiber was measured using a Canadian Standard Freeness Tester (manufactured by Tozai Seiki Co., Ltd.) The term "freeness" is also called "freeness" or "beating degree."

[0146] <Method for evaluating fiber properties> The average fiber length (mm), average fiber diameter (μm), and moisture content (%) of the fibrous binder and main fiber material were determined as follows. The average fiber length (mm), average fiber diameter (μm), acrylic ratio, and fineness ratio (%) of the fibrillated fibers were measured as follows. The water dissolution temperature of the fibrous binder and the sodium sulfate adhesion rate (%) of the polyvinyl alcohol-based fibrous binder were determined.

[0147] <Average Fiber Length> (1) Average fiber length of fibrous binder The numerical value of the cut size indicated by the supplier was used.

[0148] (2) Average fiber length of main fiber material (recycled carbon fiber) Considering the large variation in recycled carbon fiber, 20 fiber bundles were randomly selected, and each fiber bundle was measured using a vernier caliper, and the average value was calculated.

[0149] (3) Average Fiber Length of Fibre Fibre having a fiber length of 0.2 mm or more, excluding fibres having a fiber length of less than 0.2 mm, was diluted to a solid content of 0.1 g and a slurry of 300 cc, and the mean fiber length was measured by a weighted average using an L&W Fiber Tester Plus Code 912 (manufactured by Lorentzen & Wettley) according to the following formula 1. Note that when photographing and processing the diluted sample taken, the measuring device can be set to exclude from analysis any fibre images that are clearly inappropriate for measuring the fibre length, fibre diameter, fineness ratio and the like of the fibrillated fibre due to circumstances such as multiple fibres being captured in an overlapping state.

[0150] <Formula 1>

[0151] <Average Fiber Diameter> (1) Average Fiber Diameter of Fibrous Binder The diameter of a fiber in terms of a perfect circle indicated by the supplier was used.

[0152] (2) Average Fiber Diameter of Fibrillated Fibers Excluding fibers with a fiber length of less than 0.2 mm, fibers with a fiber length of 0.2 mm or more were diluted so that the solid content of the fibrillated fibers was 0.1 g and the slurry volume was 300 cc. Using an L&W Fiber Tester Plus Code 912 (manufactured by Lorentzen & Wettley) as a measuring device, the average fiber diameter (Mean Width) was measured by a weighted average using the fiber length (Length) according to the following Equation 2.

[0153] <Formula 2>

[0154] (3) Average fiber diameter of the main fiber material The fiber diameter of the main fiber material was determined by measuring 10 fibers randomly extracted from a 500x magnification image using a Schottky field emission scanning electron microscope JSM-7900F (manufactured by JEOL Ltd.), and calculating the average value.

[0155] <Moisture Content> (1) Moisture Content of Fibrous Binder The moisture content of the fibrous binder was determined using a halogen moisture meter HB43 (manufactured by Mettler Toledo K.K.).

[0156] (2) Moisture Content of Main Fiber Material The moisture content of the main fiber material was determined using a halogen moisture meter HB43 (manufactured by Mettler Toledo K.K.).

[0157] <Water dissolution temperature of moist heat-adhesive type fibrous binder> The water dissolution temperature indicated by the supplier was used.

[0158] <Glauber's Sodium Adhesion Rate of Polyvinyl Alcohol-Based Fibrous Binder> The numerical value of the glauber's sodium sulfate adhesion rate indicated by the supplier was used.

[0159] <Cryl ratio of fibrillated fiber> Ultraviolet or infrared light was irradiated onto a slurry of fibrillated fiber, and the reduction in transmitted light from the incident light was determined for each ultraviolet or infrared light source. The reduction in ultraviolet light and the reduction in infrared light were used to calculate the cryl ratio based on the following formula 1. An L&W Fiber Tester Plus Code 912 (Lorentzen & Wettley) was used as the measuring instrument.

[0160] <Equation 3> (CR)=(UVR) / (IRR) In equation 3, CR, UVR, and IRR are as follows.

[0161] CR: Krill ratio UVR: UV reduction IRR: Infrared reduction

[0162] <Fineness ratio of fibrillated fibers> The ratio of fine fibers (fibers with a fiber length of less than 0.2 mm), i.e., the mean fines ratio, was measured using an L&W Fiber Tester Plus Code 912 (manufactured by Lorentzen & Wettley) after diluting the fibrillated fibers with water so that the solid content was 0.1 g and the slurry volume was 300 cc. The calculation method was according to the following formula 4b.

[0163] The general formula for the fineness ratio can be expressed as the following formula 4: <Formula 4a> (FR) = (FFL) / (WFL) x 100 (%) In formula 4a, FR, FFL, and WFL are as follows: FR: fineness ratio FFL: total length of fine fibers (fibers with a fiber length of less than 0.2 mm) WFL: total length of all fibers (fibers with a fiber length of less than 0.2 mm + fibers with a fiber length of 0.2 mm or more)

[0164] When Equation 4a is rewritten as an equation for finding a weighted average in the same format as Equations 1 and 2, it is as shown in Equation 4b below.

[0165] <Formula 4b>

[0166] <Dimensions and Weight of Fiber Molded Product> The dimensions of the fiber molded product were measured using a ruler or the like as follows. The measurement samples of the fiber molded product were conditioned overnight in an atmosphere of 23°C and 50% RH. The weight of the fiber molded product after conditioning was measured using an electronic balance. The basis weight and density of the fiber molded product were calculated using the obtained measurements as follows.

[0167] <Thickness of Fiber Molded Article> The sheet thickness (unit: μm) of a sheet-like fiber molded article was measured using a thickness tester TM600 (manufactured by Kumagai Riki Kogyo Co., Ltd.) at a surface pressure of 100 kPa.

[0168] <Basis weight of fiber molded body> The basis weight (unit: g / m) of a sheet-shaped fiber molded body is calculated from its weight and area. 2 ) was sought.

[0169] <Density of fiber molded body> The density of the fiber molded body (unit: g / cm 3 ) is the basis weight of the fiber molding (unit: g / m 2 The basis weight and sheet thickness of the fiber molding were calculated from the results of the measurements made by the above methods.

[0170] <Tensile strength of fiber molding> A sheet-like fiber molding was conditioned at 23°C and 50% humidity for 12 hours, and a test piece (width 15 mm, length 150 mm) was cut out under this atmosphere, and the tensile strength (kN / m) was measured using an L&W Tensile Tester Code 066 (Lorentzen & Wettley) as a measuring device.

[0171] <Fiber shedding in fiber moldings (visual evaluation)> When the fiber molding was cut with a cutter (NT Cutter Pro H-1P, manufactured by NT), the state of fiber shedding was visually confirmed (Evaluation A: Almost no fiber shedding, Evaluation B: Slight fiber shedding). Image samples of the sheet surface and edge (cut portion) of Example S5 (1) and Comparative Example S3 (1) are shown in Figures 1 and 2, respectively. Figure 1 is an image sample of Evaluation A, and Figure 2 is an image sample of Evaluation B. Comparing Figures 1 and 2, it can be seen that Comparative Example S3 (1) had a lot of fluffing, while Example S5 (1) had significantly reduced fluffing.

[0172] The physical properties of the fibrous binder and fibrillated fiber used as binder components are shown in Table 1-1. Table 1-2 shows the measurement results for a sheet-shaped recycled carbon fiber molding of blend (1) (95.5% recycled carbon fiber, 4.5% binder component). Table 1-3 shows the measurement results for a sheet-shaped carbon fiber molding of blend (2) (95.5% carbon fiber, 4.5% binder component). Table 1-4 shows the measurement results for a sheet-shaped glass fiber molding of blend (3) (95.5% glass fiber, 4.5% binder component). Table 1-5 shows the measurement results for a sheet-shaped PET fiber molding of blend (4) (95.5% PET fiber, 4.5% binder component).

[0173]

[0174]

[0175]

[0176]

[0177]

Claims

1. A fiber molding comprising a main fiber material and a moist heat-bonding type fibrous binder, the content ratio of the main fiber material to the moist heat-bonding type fibrous binder being 1 to 20 parts by weight of the moist heat-bonding type fibrous binder per 100 parts by weight of the main fiber material, and the water dissolution temperature of the moist heat-bonding type fibrous binder being 30 to 95°C.

2. The fibrous molding according to claim 1, wherein the heat-and-moisture adhesive fibrous binder is a polyvinyl alcohol-based heat-and-moisture adhesive fibrous binder.

3. The fiber molding according to claim 1, wherein the main fiber material is one or more selected from the group consisting of carbon fiber, glass fiber, metal fiber, natural fiber, cellulose-based fiber, regenerated fiber, semi-synthetic fiber, and synthetic fiber.

4. The fiber molding according to claim 1, wherein the main fiber material is one or more fibers selected from the group consisting of carbon fiber, glass fiber, and PET-based fiber.

5. The fiber molding according to claim 1, wherein the main fiber material is a virgin carbon fiber, a recycled carbon fiber, or a mixture thereof, or a mixture of virgin carbon fiber, recycled carbon fiber, or a mixture thereof with one or more fibers selected from the group consisting of glass fiber, metal fiber, natural fiber, cellulosic fiber, recycled fiber, semi-synthetic fiber, and synthetic fiber.

6. The fibrous molding according to claim 1, wherein the moisture content of the wet-adhesive fibrous binder is 0.5 to 25%.

7. The fibrous molding according to claim 6, wherein the wet adhesive fibrous binder is a polyvinyl alcohol-based wet heat adhesive fibrous binder.

8. The fiber molding according to claim 6, wherein the main fiber material is one or more selected from the group consisting of carbon fiber, glass fiber, metal fiber, natural fiber, cellulose-based fiber, regenerated fiber, semi-synthetic fiber, and synthetic fiber.

9. The fiber molding according to claim 6, wherein the main fiber material is one or more fibers selected from the group consisting of carbon fiber, glass fiber, and PET-based fiber.

10. The fiber molding according to claim 6, wherein the main fiber material is a virgin carbon fiber, a recycled carbon fiber, or a mixture thereof, or a mixture of virgin carbon fiber, recycled carbon fiber, or a mixture thereof with one or more fibers selected from the group consisting of glass fiber, metal fiber, natural fiber, cellulosic fiber, recycled fiber, semi-synthetic fiber, and synthetic fiber.

11. The fiber molding according to claim 1, further comprising fibrillated fibers, the fibrillated fibers having a acrylic ratio of 1.25 to 3.00, and the content ratio of the main fiber material to the heat-and-moisture bonding fibrous binder and fibrillated fibers is 1 to 20 parts by weight per 100 parts by weight of the main fiber material.

12. The fiber molding according to claim 11, wherein the weight ratio of the heat-and-moisture adhesive fibrous binder to the fibrillated fibers in the fiber molding is 5:95 to 95:

5.

13. The fibrous molding according to claim 11, wherein the fineness of the fibrillated fibers is 95% or less.

14. A fiber-reinforced resin molding comprising the fiber molding according to any one of claims 1 to 13 and a resin component impregnated into the fiber molding.

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