Paper product, cured product, and method for producing paper product

Abstract

To provide a sheet made product that can improve a balance between moldability and mechanical strength.SOLUTION: A sheet made product 21 contains thermosetting resin A, reinforcing fibers B and inorganic filler, with a content of the reinforcing fibers B being 35 vol.% or less with respect to the sheet made product 21f, and the reinforcing fibers B including reinforcing fibers having fiber length of 9 mm or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a paper article, a cured product, and a method for producing a paper article. [Background technology]

[0002] The application of papermaking techniques, which are a technology used in papermaking, has been considered as a manufacturing method for fiber-reinforced plastics (FRP), in which monofilaments such as organic fibers, carbon fibers, and glass fibers are dispersed in a resin matrix.

[0003] For example, Patent Document 1 describes a fiber-reinforced resin that is composed of a reinforcing fiber substrate made of a group of fiber bundles of short reinforcing fibers and a matrix resin made of a thermosetting resin. Patent Document 1 describes that a certain number or more of the fiber bundles of the reinforcing fiber substrate are split to have a specific number of single yarns, the number of straight fiber bundles is a specific number or more, the orientation of the fiber bundles is two-dimensionally pseudo-isotropic, and the volume content of the reinforcing fibers is a specific number or more, thereby achieving a high degree of isotropy and exhibiting high strength. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-174605 A Summary of the Invention [Problem to be solved by the invention]

[0005] The technology disclosed in Patent Document 1 focuses on the use of short fibers among the reinforcing fibers of the paper product, and thereby aims to increase the mechanical strength while reducing the anisotropy of the strength caused by the reinforcing fibers. However, there is still room for improvement in the mechanical strength obtained by using the short fibers. On the other hand, it has been known that moldability of molded articles using reinforcing fibers having a long fiber length tends to decrease. The present inventors therefore conducted new research on the premise of using reinforcing fibers with a relatively long fiber length for the paper product. As a result, they discovered that the balance between mechanical strength and moldability could be improved by combining a thermosetting resin and an inorganic filler and controlling the content of the reinforcing fibers on the premise of using reinforcing fibers with a fiber length of 9 mm or more, and thus completed the present invention. [Means for solving the problem]

[0006] According to the present invention, A papermaking product comprising a thermosetting resin, a reinforcing fiber, and an inorganic filler, The content of the reinforcing fibers is 35% by volume or less relative to the paper body, The paper article is provided, in which the reinforcing fibers include reinforcing fibers having a fiber length of 9 mm or more.

[0007] Further, according to the present invention, A step of kneading a thermosetting resin and an inorganic filler to obtain a thermosetting resin composition; A step of dispersing the thermosetting resin composition and reinforcing fibers in a dispersion medium, and then removing the dispersion medium by a papermaking method to obtain a paper body; A method for producing a paper article, comprising: The method for producing a paper article is provided, in which the content of the reinforcing fibers is 35 volume % or less relative to the paper article, and the reinforcing fibers include reinforcing fibers having a fiber length of 9 mm or more. Effect of the Invention

[0008] According to the present invention, a paper article capable of improving the balance between moldability and mechanical strength is provided. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a cross section and a part of a plane of a paper article according to an embodiment of the present invention. FIG. [Diagram 2] 2 is a schematic cross-sectional view showing an example of a method for producing a paper article according to the present embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are given the same reference numerals and the description will be omitted as appropriate.

[0011] <Paperwork> 1 is a schematic diagram showing a cross section and a part of a plan view of a paper article 21 according to this embodiment. The paper article 21 is a molding material in a B-stage state in which reinforcing fibers B are dispersed in a matrix resin of a thermosetting resin A. The thermosetting resin A functions as a binder that bonds the reinforcing fibers B together, and also functions as a molding material for obtaining a molded article from the paper article 21 by a subsequent heat treatment.

[0012] In Fig. 1, the region of the paper product indicated by the dotted line is a partially enlarged schematic diagram of a cross section and a plan view. The paper product 21 according to this embodiment is obtained by a papermaking method described later, and has the following structural characteristics 1 to 3. (Feature 1) In a plan view of the surface of the paper article 21, the reinforcing fibers B are randomly oriented. (Feature 2) In a cross-sectional view in the thickness direction of the paper article 21, the orientation state of the reinforcing fibers B is highly controlled, and the reinforcing fibers B are oriented in a specific direction. In other words, in the thickness direction of the paper article 21, the reinforcing fibers B are in a laminated state. (Feature 3) Reinforcing fibers B are bonded together by thermosetting resin A.

[0013] Since the paper product 21 is formed by a papermaking method, the thermosetting resin A is uniformly dispersed and the paper product 21 has excellent processability. This also improves the design of the paper product 21. Furthermore, the papermaking method places few restrictions on the combination of materials that can be used to form the paper product 21.

[0014] The paper product 21 according to this embodiment contains thermosetting resin A, reinforcing fiber B, and inorganic filler (not shown), with the content of reinforcing fiber B being 35 volume % or less relative to the paper product 21, and reinforcing fiber B containing reinforcing fiber having a fiber length of 9 mm or more. This improves the elastic modulus of the cured product obtained by curing the paper product 21, while maintaining good moldability when processing the paper product 21, achieving a high level of balance between the two.

[0015] The paper product 21 of this embodiment contains reinforcing fibers B, but at least contains reinforcing fibers with a fiber length of 9 mm or more, and may contain fibers with a fiber length of less than 9 mm. From the viewpoint of improving mechanical strength, the length of the contained fibers is preferably 10 mm or more, and more preferably 11 μm or more. In this embodiment, the fiber length is not the average length of all the reinforcing fibers B, but the length of each fiber contained in the paper product 21 as the reinforcing fibers B. On the other hand, the upper limit of the fiber length is not particularly limited, but from the viewpoint of dispersing the reinforcing fiber B well during the manufacturing process of the paper product 21, it is preferably 40 mm or less, more preferably 30 mm or less, and furthermore from the viewpoint of improving handleability, it is even more preferably 20 mm or less.

[0016] In this embodiment, the proportion of reinforcing fibers having a fiber length of 9 mm or more relative to the total amount of reinforcing fibers B is preferably 80 volume % or more, more preferably 85 volume % or more, even more preferably 90 volume % or more, and may be 99 volume %. In order for the paper product 21 of this embodiment to contain reinforcing fibers with a fiber length of 9 mm or more, it is preferable to use reinforcing fibers with a fiber length of 9 mm or more as the raw material for the paper product 21. In addition, the fiber length of the reinforcing fiber B in the paper product 21 can be confirmed, for example, by ashing the paper product or the cured material, dispersing the ashed reinforcing fiber in a liquid, and then transferring a portion of the dispersion onto a slide glass and observing the reinforcing fiber with an optical microscope.

[0017] The paper product 21 of this embodiment is obtained by using a dispersion medium in which the thermosetting resin composition and the reinforcing fiber B are each dispersed independently, and the inorganic filler is finely dispersed in the thermosetting resin composition. In other words, the paper product 21 of this embodiment is obtained by dispersing the thermosetting resin composition containing the thermosetting resin A having the inorganic filler finely dispersed therein and the reinforcing fiber B in a dispersion medium described later, and forming the paper product. As a result, the inorganic filler is positioned near the thermosetting resin A in the paper product 21, so that the elastic modulus of the thermosetting resin A can be effectively increased by the inorganic filler, and since the reinforcing fibers B contain reinforcing fibers having a fiber length of 9 mm or more, the bending elastic modulus of the entire cured paper product can be further improved.

[0018] Hereinafter, each component contained in the paper product 21 of this embodiment will be described.

[0019] [Reinforced fiber] The reinforcing fibers according to the present embodiment are not limited, and specifically, metal fibers; inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers; natural fibers such as wood fibers, cotton, hemp, and wool; regenerated fibers such as rayon fibers; semi-synthetic fibers such as cellulose fibers; synthetic fibers such as polyamide fibers, aramid fibers, polyimide fibers, polyvinyl alcohol fibers, polyester fibers, acrylic fibers, polyparaphenylene benzoxazole fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, and ethylene vinyl alcohol fibers can be used. As the reinforcing fibers, one or more of the above specific examples can be used in combination. As the reinforcing fibers, it is preferable to use inorganic fibers or synthetic fibers, for example, from the above specific examples. In addition, it is preferable to use, for example, glass fibers or carbon fibers as inorganic fibers. Furthermore, it is preferable to use, for example, aramid fibers as synthetic fibers. This can suitably reinforce paper-made bodies and molded products. It is also preferable from the viewpoint of further improving the dispersibility of the reinforcing fibers in the slurry.

[0020] The content of the reinforcing fibers is preferably adjusted appropriately depending on the total amount including the content of the inorganic filler described below. The total content of the reinforcing fibers and the inorganic filler is preferably 40 to 80% by volume, more preferably 45 to 70% by volume, and even more preferably 50 to 60% by volume, based on the volume of the paper product. By setting the total content of the reinforcing fibers and the inorganic filler at or above the upper limit, the mechanical strength of the paper product can be maintained while improving moldability. On the other hand, by setting the total content of the reinforcing fibers and the inorganic filler at or above the upper limit, the mechanical strength of the paper product can be improved while maintaining good moldability.

[0021] [Thermosetting resin] The thermosetting resin is used as a matrix resin in the paper product. Specifically, the thermosetting resin may be a phenol resin, an epoxy resin, a melamine resin, a polyurethane, or an unsaturated polyester resin. The thermosetting resin may be one or more of the above specific examples. The thermosetting resin may be a phenol resin, for example, from the above specific examples. This can improve the strength of the molded product. It is also preferable from the viewpoint of further improving the dispersibility of the reinforcing fibers.

[0022] (Phenol Resin) Specific examples of the phenolic resin include novolac-type phenolic resin, resol-type phenolic resin, and aryl alkylene-type phenolic resin. As the phenolic resin, one of these may be used alone, or two or more types having different weight average molecular weights may be used in combination, or one or more types may be used in combination with their prepolymers. As the phenolic resin, it is preferable to use, for example, novolac-type phenolic resin or resol-type phenolic resin from the above specific examples.

[0023] The novolac type phenolic resin can be appropriately selected according to the purpose as long as it is a resin obtained by reacting a phenol with an aldehyde in the absence of a catalyst or in the presence of an acid catalyst. For example, random novolac type and high ortho novolac type phenolic resins can also be used. There can be. The novolac type phenolic resin can usually be obtained by reacting the aldehydes with the phenols at a molar ratio (aldehydes / phenols) controlled to be 0.5 or more and 1.0 or less.

[0024] Specific examples of phenols used in preparing this novolac type phenolic resin include phenol, o-cresol, m-cresol, p-cresol, xylenol, alkylphenols, catechol, resorcin, etc. These phenols may be used alone or in combination of two or more.

[0025] Specific examples of aldehydes used in preparing the novolac phenolic resin include aldehyde compounds such as formaldehyde, paraformaldehyde, and benzaldehyde, as well as sources of these aldehyde compounds, or solutions of these aldehyde compounds. These aldehydes may be used alone or in combination of two or more.

[0026] Specific examples of acid catalysts used in preparing the novolac phenolic resin include organic carboxylic acids such as oxalic acid and acetic acid, organic sulfonic acids such as benzenesulfonic acid, paratoluenesulfonic acid, and methanesulfonic acid, organic phosphonic acids such as 1-hydroxyethylidene-1,1'-diphosphonic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid, and inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid. These may be used alone or in combination of two or more.

[0027] The resol type phenolic resin can be appropriately selected according to the application, so long as it is a resin obtained by reacting a phenol with an aldehyde in the presence of a basic catalyst. Incidentally, this resol type phenolic resin can usually be obtained by reacting the aldehydes while controlling the molar ratio of the phenols to the aldehydes (aldehydes / phenols) to be 1.3 or more and 1.7 or less.

[0028] Specific examples of phenols used in preparing this resol type phenolic resin include phenol, o-cresol, m-cresol, p-cresol, xylenol, alkylphenols, catechol, and resorcin. These phenols may be used alone or in combination of two or more.

[0029] Specific examples of aldehydes used in preparing the resol-type phenolic resin include aldehyde compounds such as formaldehyde, paraformaldehyde, and benzaldehyde, as well as sources of these aldehyde compounds, or solutions of these aldehyde compounds. These aldehydes may be used alone or in combination of two or more.

[0030] Specific examples of basic catalysts used in preparing resol-type phenolic resins include alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide, oxides and hydroxides of alkaline earth metals such as calcium, magnesium, and barium, sodium carbonate, aqueous ammonia, amines such as triethylamine and hexamethylenetetramine, and divalent metal salts such as magnesium acetate and zinc acetate. These may be used alone or in combination of two or more.

[0031] (Epoxy resin) The epoxy resin is not limited, and any monomer, oligomer, or polymer having two or more epoxy groups in one molecule can be used regardless of its molecular weight or molecular structure. Specific examples of epoxy resins include biphenyl type epoxy resins; bisphenol type epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type, and tetramethylbisphenol F type epoxy resins; stilbene type epoxy resins; novolac type epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins; polyfunctional epoxy resins such as triphenyl type epoxy resins exemplified by triphenol methane type epoxy resins and alkyl-modified triphenol methane type epoxy resins; phenol aralkyl type epoxy resins having a phenylene skeleton, naphthol aralkyl type epoxy resins having a phenylene skeleton, and phenol aralkyl type epoxy resins having a biphenylene skeleton. phenol aralkyl type epoxy resins such as aryl type epoxy resins (biphenyl aralkyl type epoxy resins) and naphthol aralkyl type epoxy resins having a biphenylene skeleton; naphthol type epoxy resins such as dihydroxynaphthalene type epoxy resins and epoxy resins obtained by glycidyl etherification of dihydroxynaphthalene dimers; triazine nucleus-containing epoxy resins such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; bridged cyclic hydrocarbon compound modified phenol type epoxy resins such as dicyclopentadiene modified phenol type epoxy resins; brominated type epoxy resins such as brominated bisphenol A type and brominated phenol novolac type; tris(hydroxyphenyl)methane type epoxy resins. As the epoxy resin, one of these may be used alone, or two or more different types may be used in combination.

[0032] The upper limit of the weight average molecular weight of the thermosetting resin is, for example, preferably not more than 10,000, more preferably not more than 9,000, and even more preferably not more than 8,000. This reduces the viscosity of the slurry when it is formed, and further improves the dispersibility of the reinforcing fibers and the thermosetting resin. The lower limit of the weight average molecular weight of the thermosetting resin is, for example, preferably 2000 or more, more preferably 3000 or more, and even more preferably 4000 or more. This can improve the mechanical strength of the molded product. Therefore, the anisotropy of the bending strength can be further reduced.

[0033] The lower limit of the content of the thermosetting resin in the paper product is, for example, preferably 30% by volume or more, more preferably 35% by volume or more, and even more preferably 40% by volume or more, based on the entire paper product, which can further improve the random orientation of the reinforcing fibers in the paper product. The upper limit of the content of the thermosetting resin in the paper product is, for example, preferably 70% by volume or less, more preferably 60% by volume or less, and even more preferably 55% by volume or less, based on the entire paper product. This is preferable from the viewpoint of improving the moldability of the paper product, making it easier to mold it into a desired shape, and enabling the molded product to be used in applications requiring a precise structure.

[0034] [Inorganic filler] In this embodiment, the inorganic filler is used to increase the mechanical strength. Examples of inorganic fillers include one or more selected from calcium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, aluminum oxide (alumina), crystalline or fused silica, surface-treated silica, talc, kaolin, clay, mica, dolomite, wollastonite, glass fiber, carbon fiber, glass beads, zircon, and molybdenum compounds. Among them, from the viewpoint of easily improving the balance between mechanical strength and moldability of the paper molded product as a whole, fused silica is preferred, clay is more preferred, and a mixture of these is also possible.

[0035] The inorganic filler may be surface-treated. For example, the surface treatment may be performed with a coupling agent such as a silane coupling agent. This can suppress the aggregation of the inorganic filler and provide good dispersibility. As the coupling agent, for example, primary aminosilanes such as γ-aminopropyltriethoxysilane and γ-aminopropyltrimethoxysilane can be used. When a coupling agent is used, its content is not particularly limited, but is preferably 0.05 to 3 parts by weight, and more preferably 0.1 to 2 parts by weight, relative to 100 parts by weight of the inorganic filler.

[0036] The shape of the inorganic filler can be appropriately selected depending on the purpose, and examples thereof include granular shapes such as spherical, true spherical, and amorphous shapes; true needle shapes, fibrous shapes, and plate shapes. When the inorganic filler is granular, the average particle size is preferably from 0.1 to 100 μm, more preferably from 0.1 to 50 μm, and even more preferably from 0.1 to 20 μm. By setting the average particle size of the inorganic filler to be equal to or larger than the lower limit, it is possible to obtain good dispersibility and improve the mechanical strength, whereas by setting the average particle size of the inorganic filler to be equal to or smaller than the upper limit, it is possible to maintain the dispersibility and stabilize the mechanical strength. When a fibrous inorganic filler is selected as the material, it is preferable to shorten the fiber length by cutting treatment, etc. The inorganic filler preferably has a maximum diameter of 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less. In addition, when the filler is fibrous, the cross-sectional diameter is preferably 0.1 to 20 μm.

[0037] The average particle size of the inorganic filler is the particle size (D50) that is the cumulative 50% of the volume-based particle size distribution, and can be measured with a commercially available laser type particle size distribution analyzer (for example, SALD-7000 manufactured by Shimadzu Corporation).

[0038] (Other Ingredients) In addition to the reinforcing fibers, thermosetting resins, and inorganic fillers described above, the paper product according to this embodiment may contain, for example, pulp fibers, paper-making agents, ion exchange agents, flocculants, conductivity imparting agents, flame retardants, flame retardant assistants, pigments, dyes, lubricants, release agents, compatibilizers, dispersants, crystal nucleating agents, plasticizers, heat stabilizers, antioxidants, coloring inhibitors, ultraviolet absorbers, flowability modifiers, foaming agents, antibacterial agents, vibration damping agents, deodorizing agents, sliding property modifiers, and antistatic agents. Representative components will be described below.

[0039] (Pulp fiber) The paper product according to the present embodiment may further include pulp fibers obtained by fibrillating organic fibers. Pulp fibers are not particularly limited, but include pulp-like fibers obtained by fibrillating organic fibers such as cellulose fibers such as linter pulp and wood pulp, natural fibers such as kenaf, jute, and bamboo, para-type wholly aromatic polyamide fibers and their copolymers, aromatic polyester fibers, polybenzazole fibers, meta-type aramid fibers and their copolymers, acrylic fibers, acrylonitrile fibers, polyimide fibers, and polyamide fibers. As the pulp fibers, one or a combination of two or more of the above specific examples may be used.

[0040] The method for fibrillating the organic fibers is not particularly limited, but the organic fibers can be dispersed in water to form a slurry, which is then beaten with a beater or refiner to produce the fibrillated organic fibers. The slurry concentration during beating is optional, but a solid content concentration of 0.1 to 10% by volume is preferred.

[0041] (Papermaking chemicals) A papermaking agent can be added to the paper product of this embodiment for the purpose of improving material yield, etc. The papermaking agent is not particularly limited, but examples thereof include thermoplastic resins such as acrylic polymers, vinyl polymers, polyurethanes, polyamides, polyesters, and polyethylene oxides, and one or more selected from these are used. The thermoplastic resin used as the papermaking agent preferably has at least one functional group selected from amino groups, epoxy groups, carboxyl groups, oxazoline groups, carboxylate groups, and acid anhydride groups, and may have two or more functional groups. Among these, thermoplastic resins having amino groups are more preferable.

[0042] (Ion exchange agent) The paper product of the present embodiment may contain an ion exchange agent, which is a powdery material having ion exchange ability. Specific examples of the ion exchange agent include clay minerals, scaly silica fine particles, hydrotalcites, fluorine taeniolite, and swellable synthetic mica. The ion exchange agent may be one or more of the above specific examples in combination. This is advantageous in terms of efficiently producing an aggregate of the thermosetting resin and the reinforcing fibers while maintaining the fiber length of the reinforcing fibers long.

[0043] The clay minerals may be natural or synthetic, and are not particularly limited. Examples of the clay minerals include smectite, halloysite, kanemite, kenyaite, zirconium phosphate, and titanium phosphate. The hydrotalcites are not particularly limited as long as they have ion exchange capacity. Examples of the fluorine taeniolite include, but are not limited to, lithium-type fluorine taeniolite, sodium-type fluorine taeniolite, etc. Examples of the swellable synthetic mica include, but are not limited to, sodium-type tetrasilicon fluorine mica, lithium-type tetrasilicon fluorine mica, etc., and one type may be used alone or two or more types may be used in combination.

[0044] Among these, clay minerals are more preferable, and smectite is even more preferable in that it is available in a wide range of products, from natural to synthetic. The smectite is not particularly limited as long as it has ion exchange ability, but examples thereof include montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite. The montmorillonite is a hydrous silicate of aluminum, but it may be bentonite that contains montmorillonite as a main component and also contains minerals such as quartz, mica, feldspar, and zeolite. When used in applications where coloring or impurities are a concern, synthetic smectite with fewer impurities is preferred.

[0045] Examples of powdered substances having the above-mentioned ion exchange capacity include Kunipia (bentonite) and Sumecton SA (synthetic saponite) manufactured by Kunimine Industries Co., Ltd., Sunlovely (flake-like silica microparticles) manufactured by AGC Si-Tech Co., Ltd., Somasif (swellable synthetic mica) and Lucentite (synthetic smectite) manufactured by Co-op Chemical Co., Ltd., and hydrotalcite STABIACE HT-1 (hydrotalcite) manufactured by Sakai Chemical Industry Co., Ltd., but are not limited to these.

[0046] (Flocculant) The paper product according to the present embodiment may contain, for example, a flocculant, which allows the thermosetting resin and the reinforcing fibers to be aggregated on the flock. As the flocculant, specifically, cationic polymer flocculant, anionic polymer flocculant, nonionic polymer flocculant, amphoteric polymer flocculant, etc. can be used. Examples of such flocculants include cationic polyacrylamide, anionic polyacrylamide, Hoffman polyacrylamide, Mannick polyacrylamide, amphoteric copolymer polyacrylamide, cationic starch, amphoteric starch, polyethylene oxide, etc. These polymer flocculants may be used alone or in combination of two or more. In addition, as the polymer flocculant, the polymer structure, molecular weight, amount of functional groups such as hydroxyl groups and ionic groups, etc. can be used without any particular limitation depending on the required characteristics. In addition, examples of polymer flocculants that can be commercially obtained include polyethylene oxide manufactured by Wako Pure Chemical Industries, Ltd., Kanto Chemical Industry Co., Ltd., and Sumitomo Seika Chemicals Co., Ltd.; cationic PAM Harifix manufactured by Harima Chemicals Co., Ltd.; anionic PAM Hermide B-15; amphoteric PAM Hermide RB-300; and cationic starch SC-5 manufactured by Sanwa Starch Co., Ltd., but are not limited to these.

[0047] In addition to the above-mentioned constituent materials, the paper product of this embodiment can contain a variety of additives for the purpose of adjusting production conditions or expressing required physical properties, such as stabilizers such as antioxidants and ultraviolet absorbers for improving characteristics, release agents, plasticizers, flame retardants, resin curing catalysts and curing accelerators, pigments, paper strength improvers such as dry strength improvers and wet strength improvers, retention improvers, drainage improvers, size fixing agents, defoaming agents, sizing agents such as rosin-based sizing agents for acidic papermaking, rosin-based sizing agents for neutral papermaking, alkyl ketene dimer sizing agents, alkenyl succinic anhydride sizing agents, special modified rosin-based sizing agents, and coagulants such as aluminum sulfate, aluminum chloride, and polyaluminum chloride.

[0048] <Manufacturing method of paper product> The method for producing the paper article according to this embodiment is, for example, a wet papermaking method. The method for producing a paper article according to this embodiment includes the steps of kneading a thermosetting resin and an inorganic filler to obtain a thermosetting resin composition (step 1), and dispersing the thermosetting resin composition and reinforcing fibers in a dispersion medium, and then removing the dispersion medium using a papermaking method to obtain a paper article (step 2).

[0049] [Process 1] As a method for obtaining the thermosetting resin composition, for example, a thermosetting resin, an inorganic filler, and any additives are mixed using a mixer, and then kneaded for 5 to 10 minutes using a biaxial roll or the like at, for example, 70 to 90° C. The kneaded product obtained is cooled and then pulverized to obtain a powdered thermosetting resin composition (molding material) in which the inorganic filler is finely dispersed.

[0050] The average particle size (d50) of the powdered thermosetting resin composition is preferably 10 to 100 μm, more preferably 20 to 80 μm, and even more preferably 30 to 70 μm, which makes it easier to disperse the inorganic filler inside and improve the mechanical strength of the paper product obtained later.

[0051] The content of the inorganic filler is appropriately specified depending on the content of the reinforcing fibers, but for example, it is preferably 5 volume % or more and 60 volume % or less, more preferably 7 volume % or more and 50 volume % or less, and even more preferably 10 volume % or more and 40 volume % or less, based on the total amount of the thermosetting resin composition. By setting the content of the inorganic filler to be equal to or more than the above lower limit, the mechanical strength can be improved, whereas by setting the content of the inorganic filler to be equal to or less than the above upper limit, good mechanical strength can be stably obtained.

[0052] [Process 2] Step 2 will be described below with reference to FIG.

[0053] (Slurry preparation process) First, as shown in Fig. 2(a), a thermosetting resin composition containing a thermosetting resin A and reinforcing fibers B are dispersed in a dispersion medium to prepare a slurry. The slurry may further contain other components than the flocculant among the raw material components of the paper product described above. The method for preparing the slurry is not limited, but for example, a method in which the mixture is stirred in a vessel equipped with a stirrer can be mentioned.

[0054] The thermosetting resin composition is preferably in the form of granules or powder from the viewpoint of obtaining an appropriate dispersion medium.

[0055] The dispersion medium is not limited, and specific examples thereof include water, alcohols such as ethanol, 1-propanol, 1-butanol, and ethylene glycol, ketones such as acetone, methyl ethyl ketone, 2-heptanone, and cyclohexanone, esters such as ethyl acetate, butyl acetate, methyl acetoacetate, and methyl acetoacetate, and ethers such as tetrahydrofuran, isopropyl ether, dioxane, and furfural. The dispersion medium may be one or a combination of two or more of the above specific examples.

[0056] Here, the slurry may contain, in addition to the above materials, a poly(meth)acrylic acid ester emulsion and pulp fibers.

[0057] The poly(meth)acrylic acid ester emulsion may be added after mixing and stirring the thermosetting resin A, the reinforcing fiber B, the pulp fiber if necessary, and other components if necessary in a dispersion medium, or may be mixed simultaneously with the above components. In order to disperse each component to a higher degree, the poly(meth)acrylic acid ester emulsion is preferably added after mixing and stirring the above components in a dispersion medium. Furthermore, by blending the pulp fibers, the reinforcing fibers B can be highly dispersed. Alternatively, the thermosetting resin A, the reinforcing fiber B, and the polyether oxide may be mixed in a dispersion medium to obtain a first slurry, and then the first mixed aqueous slurry may be mixed with a poly(meth)acrylic acid ester emulsion to prepare a second slurry.

[0058] (Agglutination process) In the aggregation step, an aggregating agent is added to the dispersion liquid to form aggregates. Here, the above-mentioned flocculant can be used as the flocculant. Note that, when the thermosetting resin and the reinforcing fibers are sufficiently flocculated to form an aggregate, for example, the flocculation step does not need to be performed.

[0059] (separation process) Next, the dispersion medium is removed by a papermaking method to obtain a paper body. That is, as shown in Fig. 2(b), the slurry is placed in a container having a mesh 60 on the bottom surface, whereby the dispersion medium and the aggregates are separated, and as shown in Fig. 2(c), sheet-like aggregates remain on the mesh. The aggregates contain, for example, the raw material components of the slurry.

[0060] In this embodiment, the shape of the mesh 60 can be appropriately selected to adjust the shape of the resulting paper article 21. For example, when a flat sheet-shaped mesh 60 is used, a paper article 10 having a sheet-like shape is obtained. Also, when a mesh 60 having a three-dimensional shape such as a corrugated shape or unevenness is used, a paper article 21 having a three-dimensional shape is obtained. The shape of the paper article 21 can be appropriately selected according to the shape of the molded body 20 obtained by hardening and molding it, the shape of the mold, etc. Also, the thickness of the paper article 21 can be adjusted by adjusting the amount of each of the above materials in the material slurry, or by preparing a slurry again and performing a separation process.

[0061] (Dehydration process) In the dehydration step, the aggregate is dehydrated and pressed to produce a paper body. The conditions for the dehydration press are, for example, a temperature of 20°C to 30°C and a pressure of 1kgf / cm 2More than 50kgf / cm 2 It can be as follows: Here, the dehydration press is preferably performed so that the dehydration rate of the paper product is 20% or less, for example. Note that the dehydration rate according to this embodiment refers to the mass of the dispersion medium contained in the aggregate (paper product) after the dehydration treatment, when the mass of the dispersion medium contained in the aggregate before the dehydration treatment is taken as 100%.

[0062] (drying process) Subsequently, the aggregate is dried and the dispersion medium is further removed to obtain the paper article 21. The drying method is not limited, and for example, an oven 70 as shown in FIG.

[0063] The drying temperature can be set to a temperature equal to or higher than the melting point of the thermosetting resin and equal to or lower than the reaction temperature of the thermosetting resin. That is, the paper article 21 of this embodiment is in a B-stage cured state. The reaction temperature is the temperature at which the calculated reaction rate exceeds 0% for the first time during the temperature rise process in a differential scanning calorimetry (DSC) measurement. Here, the reaction rate is calculated as follows. First, a temperature profile is measured by DSC measurement for a paper product that has not undergone a curing reaction. The heat generation amount calculated from the temperature profile of the curing reaction obtained by this is defined as A [mJ / mg], which is converted per unit mass of the heat generation peak of the curing reaction. Next, for the paper product for which the reaction rate is to be calculated, the heat generation amount B [mJ / mg] converted per unit mass of the heat generation peak of the curing reaction is calculated in the same manner. Using the above A and B, the reaction rate is calculated from the following formula. (Formula) (Reaction rate)=B / A×100[%]

[0064] (molding process) The paper article 21 may also be molded by heating and pressing it in a mold at a temperature between the melting point and the reaction temperature of the thermosetting resin. By using a mold of a desired shape, a sheet-like or three-dimensional molded product can be obtained. The molded product maintains the B-stage cured state.

[0065] <Method of manufacturing the cured product> The molded product according to the present embodiment may be further heat-treated at a temperature higher than the reaction temperature to become a cured product in a C-stage cured state. Here, the heat treatment at a temperature higher than the reaction temperature may be performed, for example, simultaneously with the molding step.

[0066] The glass transition temperature of the cured product is, for example, preferably 180° C. or higher, more preferably 230° C. or higher, and even more preferably 260° C. or higher, which can improve heat resistance. The glass transition temperature of the cured product may be, for example, 300° C. or lower.

[0067] [Application] The uses of the paper article, molding, and cured product according to the present embodiment are not limited as long as they require high mechanical properties. Specifically, the uses of the paper article, molding, and cured product according to the present embodiment are suitable for use as protective members, portable members, and the like. Specific examples of protective materials include electronic device components such as electronic device casings, transportation equipment components such as the bodies of automobiles and airplanes, and wall materials for industrial materials such as pressure vessels and buildings, which protect the contents. Protective materials are required to have properties that prevent damage such as cracks even when loads and deformations are applied from all directions. Examples of portable members include electronic device members such as the housings and internal members of portable electronic devices such as mobile phones and smartphones, and items carried by humans such as sporting goods members such as tennis rackets and golf clubs. In applications of portable members, the portable member is required to have properties that prevent damage such as cracks even if a large load or deformation is applied due to dropping the portable member or using the portable member in a way that the user did not expect from the seller. The papermaking product, molded product, and cured product according to this embodiment have small anisotropy in bending strength, and therefore can be suitably used for applications such as protective members and portable members.

[0068] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of the present invention that can achieve the object of the present invention are included in the present invention. Below, examples of reference forms are given. 1. A paper product containing a thermosetting resin, reinforcing fibers, and an inorganic filler, The content of the reinforcing fibers is 35% by volume or less relative to the paper body, The paper article, wherein the reinforcing fibers include reinforcing fibers having a fiber length of 9 mm or more. 2. The paper product according to 1., A paper article, wherein the total content of the reinforcing fibers and the inorganic filler is 40 to 80 volume % of the paper article. 3. The paper product according to 1. or 2., The thermosetting resin comprises one or more resins selected from the group consisting of phenolic resins, epoxy resins, melamine resins, polyurethanes, and unsaturated polyester resins. 4. A paper product according to any one of 1. to 3., The papermaking product, wherein the reinforcing fibers include one or more fibers selected from metal fibers, carbon fibers, glass fibers, ceramic fibers, polyamide fibers, aramid fibers, polyimide fibers, polyvinyl alcohol fibers, polyester fibers, acrylic fibers, polyparaphenylene benzoxazole fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, and ethylene vinyl alcohol fibers. 5. A paper product according to any one of 1. to 4., A paper product, wherein the proportion of reinforcing fibers having a fiber length of 9 mm or more is 80 volume % or more of the total amount of the reinforcing fibers. 6. A papermaking product according to any one of 1. to 5., The content of the thermosetting resin in the paper product is 10 to 60% by volume based on the total volume of the paper product. 7. A papermaking product according to any one of 1. to 6., The paper-formed body, wherein the inorganic filler is one or more selected from calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, aluminum oxide (alumina), crystalline or fused silica, surface-treated silica, talc, kaolin, clay, mica, dolomite, wollastonite, glass fiber, carbon fiber, glass beads, zircon, and molybdenum compounds. 8. A paper product according to any one of 1. to 7., The inorganic filler has an average particle size of 0.1 to 100 μm. 9. A cured product obtained by curing the paper-made article described in any one of 1. to 8. 10. A step of kneading a thermosetting resin and an inorganic filler to obtain a thermosetting resin composition; A step of dispersing the thermosetting resin composition and reinforcing fibers in a dispersion medium, and then removing the dispersion medium by a papermaking method to obtain a paper body; A method for producing a paper article, comprising: A method for producing a paper product, wherein the content of the reinforcing fibers is 35 volume % or less of the paper product, and the reinforcing fibers include reinforcing fibers having a fiber length of 9 mm or more. EXAMPLES

[0069] The present invention will be described in detail below using examples, but the present invention is not limited to the descriptions of these examples. Details of the components used in each of the Examples and Comparative Examples are given below.

[0070] [Examples and Comparative Examples] <Preparation of Thermosetting Resin Composition> First, raw material 1 shown below was used and mixed in a mixer according to the compounding ratio shown in Table 1. The resulting mixture was then kneaded with a biaxial roll at 80°C for 5 minutes, cooled, and pulverized to obtain a thermosetting resin composition having an average particle size of 50 μm. This resulted in a thermosetting resin composition in which inorganic filler was finely dispersed in the thermosetting resin.

[0071] (raw material 1) thermosetting resin Phenolic resin 1: Resol type phenolic resin "PR-51723" manufactured by Sumitomo Bakelite Co., Ltd. Phenolic resin 2: Novolac type phenolic resin "A-1087" manufactured by Sumitomo Bakelite Co., Ltd. Inorganic Filler Inorganic filler 1: Clay (calcined aluminum silicate) "Satenton SP-33" (average particle size 1.3 μm) manufactured by BASF Inorganic filler 2: Carbon fiber powder (PAN-based carbon fiber (Toray, T800-SC, average fiber length 4 mm) crushed and classified in a stone mill. Average particle size 60 μm)

[0072] <Preparation of paper-made object> The obtained thermosetting resin composition was used to prepare the following raw material 2. Note that the volume percentage is the same as that of the papermaking process in Example 1. Body 1 00Volume % The percentages are based on the volume of the solid.

[0073] The above raw material 2 was added to water as a dispersion medium so as to give the volume ratio (volume %; total 100 volume %) shown in Table 1, and stirred for 20 minutes to obtain a slurry with a solid concentration of 0.15 wt %. To the resulting slurry, a poly(meth)acrylic acid ester emulsion ("Himoc DR-9300" manufactured by Himo Corporation) prepared in advance was added so as to be 300 ppm relative to the solid content in the slurry, thereby flocculating the solid content in the slurry. The slurry containing the aggregates was then filtered through a 30-mesh metal screen, and the sheet-like aggregates remaining on the screen were pressed at a pressure of 3 MPa to dehydrate them to a dehydration rate of 20%. The dehydrated aggregates were dried at 70°C for 3 hours to obtain a sheet-like paper product in a B-stage state. The dehydration rate refers to the mass of water contained in the preform (paper product) after dehydration, when the mass of water contained in the preform (before dehydration) is taken as 100%. As a result, a paper article was obtained in which the inorganic filler was finely dispersed in the thermosetting resin.

[0074] The following measurements and evaluations were carried out for each of the obtained paper articles. The results are shown in Table 1.

[0075] (Mechanical strength: Bending strength) The paper molded product was heated at a mold temperature of 180°C and a molding pressure of 80 MPa for 15 minutes, and then heat-treated in an oven set at 180°C for 8 hours to obtain a cured product. Using the obtained cured product, test pieces measuring 10 mm in width, 80 mm in length, and 4 mm in thickness were prepared in accordance with ISO178, and the flexural modulus (GPa) of the prepared test pieces was measured by a three-point bending test. The load direction in the bending test was the papermaking direction (gravity direction).

[0076] (Moldability) The appearance of the obtained papermaking product was visually observed, and its specific gravity was measured and evaluated according to the following criteria. Note that "resin smear" refers to voids, and is defined as an area where resin, reinforcing fiber, and inorganic filler are not present. Also, "target value" refers to a value calculated from the amount of raw materials charged. ○: No visible resin smears, specific gravity difference from target value is less than 0.02 △: No visible resin smudges, specific gravity difference from target value is 0.02 or more but less than 0.1 ×: Blurring is visually observed, and the difference between the specific gravity and the target value is 0.1 or more.

[0077] [Table 1] [Explanation of symbols]

[0078] 21 Paper model 60 mesh 70 Oven A Thermosetting resin B Fiber filler

Claims

1. A papermaking product comprising a thermosetting resin, a reinforcing fiber, and an inorganic filler, The content of the reinforcing fibers is 35% by volume or less relative to the paper body, The total content of the reinforcing fiber and the inorganic filler is 40 to 60 volume % of the papermaking body, The reinforcing fibers include reinforcing fibers having a fiber length of 9 mm or more, The inorganic filler is one or more selected from calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, aluminum oxide (alumina), crystalline or fused silica, surface-treated silica, talc, kaolin, clay, mica, dolomite, wollastonite, cut glass fiber, glass beads, zircon, and molybdenum compounds, and is in the form of granules, needles, or plates.

2. The paper article according to claim 1, The thermosetting resin comprises one or more resins selected from the group consisting of phenolic resins, epoxy resins, melamine resins, polyurethanes, and unsaturated polyester resins.

3. The paper product according to claim 1 or 2, The papermaking product comprises one or more reinforcing fibers selected from metal fibers, carbon fibers, glass fibers, ceramic fibers, polyamide fibers, aramid fibers, polyimide fibers, polyvinyl alcohol fibers, polyester fibers, acrylic fibers, polyparaphenylene benzoxazole fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, and ethylene vinyl alcohol fibers.

4. The papermaking product according to any one of claims 1 to 3, A paper product, wherein the proportion of reinforcing fibers having a fiber length of 9 mm or more is 80 volume % or more relative to the total amount of the reinforcing fibers.

5. The papermaking product according to any one of claims 1 to 4, The content of the thermosetting resin is 10 to 60 volume % based on the total amount of the paper product.

6. The papermaking product according to any one of claims 1 to 5, The inorganic filler has an average particle size of 0.1 to 100 μm.

7. A cured product obtained by curing the paper article according to any one of claims 1 to 6.

8. A step of kneading a thermosetting resin and an inorganic filler to obtain a thermosetting resin composition; A step of dispersing the thermosetting resin composition and reinforcing fibers in a dispersion medium, and then removing the dispersion medium by a papermaking method to obtain a paper body; A method for producing a paper article, comprising: A method for producing a paper body, wherein the content of the reinforcing fibers in the paper body is 35 volume % or less relative to the paper body, and the reinforcing fibers include reinforcing fibers having a fiber length of 9 mm or more.

9. A method for producing the paper article according to claim 8, comprising: The method for producing a paper product, wherein the total content of the reinforcing fibers and the inorganic filler in the paper product is 40 to 60 volume % of the paper product.

10. A method for producing the paper article according to claim 8 or 9, comprising the steps of: The method for producing a paper product, wherein the inorganic filler is one or more selected from calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, aluminum oxide (alumina), crystalline or fused silica, surface-treated silica, talc, kaolin, clay, mica, dolomite, wollastonite, cut glass fiber, glass beads, zircon, and molybdenum compounds, and is granular, acicular, or plate-like.

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