Manufacturing method of molded body

Abstract

To provide a method capable of producing a molded article having good mechanical strength by suppressing the reduction in strength due to the orientation of a reinforcing fiber.SOLUTION: There is provided a method for producing a molded article 41 which comprises: a step of dispersing a thermosetting resin A and a reinforcing fiber B in a dispersion medium, followed by removing the dispersion medium using a papermaking method to obtain a papermaking article 11; a step of mixing the papermaking article 11 and a dispersant C to obtain a papermaking mixture 21; a step of obtaining an elementary article 31 by pressing and molding the papermaking mixture 21 while removing the dispersant C from the papermaking mixture 21; and a step of pressing, heating and curing the elementary article 31 to obtain a moded article 41.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a molded article. [Background technology]

[0002] Conventionally, molded articles obtained from paper products can be given desired properties by selecting the types of reinforcing fibers and resins used, and they have a high degree of design freedom, so they have been used in a variety of articles. In particular, paper products using reinforcing fibers and molded articles obtained therefrom have attracted attention as materials that are lightweight and have high mechanical strength, because the mechanical strength of the reinforcing fibers can be effectively exerted.

[0003] Patent Document 1 discloses a method for obtaining a substrate for a fiber-reinforced plastic molded body by dispersing a matrix resin and reinforcing fibers in a viscous dispersion liquid using a special device, and then removing the dispersion medium using a papermaking method. Patent Document 1 also discloses that the greater the viscosity of the dispersion liquid, the better the dispersibility of the reinforcing fibers and the less breakage or breakage of the reinforcing fibers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-37580 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the prior art such as Patent Document 1, the paper product obtained by the papermaking method is then cured by applying heat and pressure from the top and bottom (thickness direction) to form a finished product, resulting in the reinforcing fibers being laminated in layers. As a result, although the reinforcing fibers are arranged two-dimensionally randomly in the in-plane direction of the paper product, they are arranged parallel to the out-of-plane direction. Therefore, when the paper product is used as is, the reinforcing fiber layers of the paper product are prone to peeling, and the mechanical strength between the layers (in the in-plane direction) is insufficient.

[0006] Therefore, the present inventors conducted extensive research from the perspective of obtaining a new molded body using a paper product, in order to obtain high mechanical strength from the reinforcing fibers while improving the mechanical strength between the reinforcing fiber layers of a conventional paper product. As a result, they discovered that by adding a dispersant to the paper product after obtaining a paper product using a conventional papermaking method and mixing it, it is possible to loosen the reinforcing fibers oriented in the in-plane direction of the paper product. They then found that by molding a mixture of the paper product and dispersant, removing the dispersant, and then heat-pressing and molding the molded body to obtain a molded body, it is possible to suppress the decrease in strength caused by the orientation of the reinforcing fibers, and completed the present invention. [Means for solving the problem]

[0007] According to the present invention, a step of dispersing a thermosetting resin and reinforcing fibers in a dispersion medium, and then removing the dispersion medium using a papermaking method to obtain a paper product; a step of mixing the paper product with a dispersant to obtain a paper-making mixture; a step of removing the dispersant from the papermaking mixture while pressing and molding the papermaking mixture to obtain a preform; a step of applying pressure and heat to harden the green body to obtain a molded body; A method for producing a molded body is provided, comprising: [Effects of the Invention]

[0008] According to the present invention, a method for producing a molded article having good mechanical strength can be provided, which can suppress a decrease in strength due to the orientation of reinforcing fibers. Furthermore, according to the present invention, a method for producing a molded article can be provided, which can improve the degree of freedom in designing the shape of the molded article by using a mixture of a paper product and a dispersant. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of a method for manufacturing a paper article according to the present embodiment. FIG. [Figure 2] 1A to 1C are cross-sectional schematic views showing an example of a method for producing a molded body according to the present embodiment. [Figure 3] FIG. 2 is a perspective view showing an example of a molded body according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] <Method of manufacturing molded body> Fig. 1 is a cross-sectional view showing an example of a method for producing a paperboard according to the present embodiment, and Fig. 2 is a cross-sectional view showing an example of a method for producing a molded article according to the present embodiment. The following description will be given with reference to Figs. 1 and 2.

[0012] The method for producing the molded body 41 of this embodiment includes the following steps. [Step 1] A step of dispersing a thermosetting resin A and reinforcing fibers B in a dispersion medium, and then removing the dispersion medium using a papermaking method to obtain a paper product 11. [Step 2] A step of mixing the papermaking product 11 with the dispersant C to obtain the papermaking mixture 21 [Step 3] A step of obtaining a preform 31 by pressing and molding the papermaking mixture 21 while removing the dispersant C from the papermaking mixture 21. [Step 4] A step of obtaining a molded body 41 by applying pressure and heat to harden the base body 31 Steps 1 to 4 are carried out in this order. Each step will be described in detail below.

[0013] [Process 1: Obtaining a paper product] 1 is a schematic cross-sectional view illustrating a method for manufacturing a paper article 11 of this embodiment. The method for manufacturing a paper article 11 of this embodiment includes, for example, the following steps. (Step 1a) A step of mixing a thermosetting resin A and reinforcing fibers B in a dispersion medium to prepare a slurry. (Step 1b) A step of placing the obtained slurry in a container with a mesh on the bottom surface and separating the dispersion medium. (Step 1c) A step of dehydrating and pressing the agglomerates remaining on the mesh. (Step 1d) Drying. Each step will be described in detail below.

[0014] (Step 1a) As shown in Fig. 1(a), the slurry is prepared by mixing and stirring a thermosetting resin A and a reinforcing fiber B in a dispersion medium. A known method can be used for mixing in the dispersion medium, for example, a method of stirring in a vessel equipped with a stirrer can be used.

[0015] The dispersion medium is not limited, and specific examples 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. As the dispersion medium, one or a combination of two or more of the above specific examples can be used. Among these, water is preferably used because it is easily available, has a low environmental impact, and is highly safe.

[0016] The various components contained in the slurry will be described below.

[0017] ·Thermosetting resin A The thermosetting resin A may be one or more selected from phenolic resins, epoxy resins, unsaturated polyester resins, melamine resins, and polyurethanes. Among these, from the viewpoint of obtaining high mechanical strength, it is preferable to include phenolic resins and epoxy resins, and it is more preferable to include phenolic resins.

[0018] The blending amount of the thermosetting resin A is preferably 5% by volume or more, more preferably 20% by volume or more, and even more preferably 30% by volume or more, based on the entire paper product 11. This makes it easier to improve processability. On the other hand, the blending amount of thermosetting resin A is preferably 90% by volume or less, more preferably 70% by volume or less, and even more preferably 60% by volume or less, based on the entire paper product 11. This makes it possible to more effectively improve the mechanical strength of the reinforcing fibers B of the paper product 11.

[0019] Reinforced fiber B Examples of the reinforcing fiber B used in this embodiment include, but are not limited to, natural fibers such as metal fibers, wood fibers, cotton, hemp, and wool; regenerated fibers such as rayon; semi-synthetic fibers such as cellulose fibers; synthetic fibers such as polyamide fibers, aramid fibers, polyimide fibers, polyvinyl alcohol fibers, polyester fibers, acrylic fibers, polyparaphenylenebenzoxazole fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, and ethylene vinyl alcohol fibers; carbon fibers; and inorganic fibers such as glass fibers and ceramic fibers. The reinforcing fiber B may be used alone or in combination of two or more. Among these, carbon fibers and inorganic fibers are preferred from the viewpoint of obtaining high mechanical strength.

[0020] The fiber length of the reinforcing fiber B is preferably selected depending on the required properties, and is preferably, for example, 500 μm or more and 10 mm or less. By setting the fiber length to the above lower limit or more, properties such as mechanical strength and rigidity can be exhibited. On the other hand, by setting the fiber length to the above upper limit or less, good molding processability can be ensured.

[0021] The diameter of the reinforcing fibers B is preferably 1 μm or more and 100 μm or less, and more preferably 5 μm or more and 80 μm or less. By setting the diameter of the reinforcing fibers B to be equal to or greater than the above lower limit, the mechanical strength of the molded body 41 can be ensured, and by setting the diameter to be equal to or less than the above upper limit, molding processability can be ensured.

[0022] The fiber length and diameter of the reinforcing fibers B can be confirmed, for example, by observing the obtained paper product 11 or molded product 41 with an electron microscope. Furthermore, the average fiber length and average diameter can be determined by selecting a total of 100 reinforcing fibers B observed from the surface of the obtained paper product 11 or molded product 41 and calculating the average value.

[0023] The blending amount of the reinforcing fibers B is preferably 30 to 60% by volume, and more preferably 40 to 50% by volume, of the paper product 11. By setting the blending amount of reinforcing fiber B to the above lower limit or more, the mechanical strength can be improved. On the other hand, by setting the blending amount of reinforcing fiber B to the above upper limit or less, the reinforcing fiber B can be maintained in a good and uniform dispersion, and the variation in the mechanical strength of the papermaking product 11 and the molded product 41 can be suppressed.

[0024] Pulp fiber The paper article 11 and the slurry may contain pulp fibers, which allows the thermosetting resin A to aggregate more effectively. Pulp fibers refer to fibrillated organic fibers. Organic fibers are a general term for fibers, both natural and synthetic, that contain organic substances as their main component. Specific examples of pulp fibers include cellulose fibers such as linter pulp and wood pulp, natural fibers such as kenaf, jute, and bamboo, and pulp-like fibers obtained by fibrillating synthetic fibers such as 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. Pulp fibers may be used singly or in combination of two or more types.

[0025] The pulp fiber content is preferably 0.5% by volume or more, more preferably 1.5% by volume or more, and even more preferably 3% by volume or more, of the entire paper product 11. This allows the thermosetting resin A to more effectively aggregate during the manufacturing process, thereby enabling the manufacture of a more stable molded product 41. On the other hand, the pulp content is preferably 15% by volume or less, more preferably 10% by volume or less, and even more preferably 6% by volume or less, based on the entire paper product 11. This makes it possible to more effectively improve the mechanical and thermal properties of the molded body 41.

[0026] Flocculant The paper product 11 and the slurry may contain a flocculant. The flocculant has the function of agglomerating the thermosetting resin A and the reinforcing fibers B into flocks in the papermaking method for producing the paper product 11, which will be described later. This allows for more stable production of the paper product 11 and the molded body 41.

[0027] The flocculant may include, for example, one or more selected from cationic polymer flocculants, anionic polymer flocculants, nonionic polymer flocculants, and amphoteric polymer flocculants. Examples of such flocculants include cationic polyacrylamide, anionic polyacrylamide, Hoffmann polyacrylamide, Mannic polyacrylamide, amphoteric copolymer polyacrylamide, cationized starch, amphoteric starch, polyethylene oxide, etc. Furthermore, the polymer structure, molecular weight, and amount of functional groups such as hydroxyl groups and ionic groups of the flocculant can be adjusted without particular limitation depending on the required properties.

[0028] Poly(meth)acrylate emulsion The paper article 11 and the slurry may further contain a poly(meth)acrylic ester emulsion. The poly(meth)acrylic ester emulsion may be added after the thermosetting resin A, the reinforcing fiber B, and any other components are mixed and stirred in a dispersion medium, or may be mixed simultaneously with the above components. To more thoroughly disperse the various components, the poly(meth)acrylic ester emulsion is preferably added after the above components are mixed and stirred in a dispersion medium.

[0029] ·others In this embodiment, the paper product 11 and the slurry may contain one or more additives selected from the group consisting of stabilizers such as antioxidants and ultraviolet absorbers for improving properties, 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 aids, drainage improvers, size fixing agents, antifoaming agents, sizing agents such as rosin-based sizing agents for acidic papermaking, rosin-based sizing agents for neutral papermaking, alkyl ketene dimer-based sizing agents, alkenyl succinic anhydride-based sizing agents, and specially modified rosin-based sizing agents, and coagulants such as aluminum sulfate, aluminum chloride, and polyaluminum chloride, for the purpose of adjusting production conditions or achieving required physical properties.

[0030] These various components are dissolved or dispersed in the slurry by known methods before use.

[0031] (Step 1b) In this embodiment, as shown in Fig. 1(b), the dispersion medium is separated by placing the obtained slurry in a container having a mesh 60 on the bottom surface. As a result, as shown in Fig. 1(c), the aggregates contained in the slurry remain in a sheet shape on the mesh 60.

[0032] Here, since the reinforcing fibers B have a certain length, they are deposited on the surface of the mesh 60 in a layered state in which they are entangled with each other.

[0033] The thickness of the sheet-like paper product 11 can be adjusted by adjusting the amounts of various components in the material slurry or by repeating the process of preparing a slurry again and separating it.

[0034] Furthermore, by appropriately selecting the shape of the mesh 60, it is possible to adjust the shape of the sheet-like paper product 11 to be obtained later.

[0035] (Step 1c) Next, the aggregate remaining on the mesh 60 is dewatered and pressed to obtain a sheet-like paper article 11 (FIG. 1(c)). The conditions for the dewatering and pressing are, for example, a temperature of 20° C. or higher and 30° C. or lower, and a pressure of 1 kgf / cm. 2 More than 50kgf / cm 2 It can be as follows: Here, the dehydration press is preferably carried out so that the dehydration rate of the sheet-like paper article 11 is 20% or less. Note that the dehydration rate in this embodiment refers to the mass of the dispersion medium contained in the aggregate after the dehydration treatment, when the mass of the dispersion medium contained in the aggregate before the dehydration treatment is taken as 100%.

[0036] (Step 1d) In the drying step, the aggregate is heat-treated in an oven 70 as shown in Fig. 2(d), thereby further removing the dispersion medium from the sheet-like paper product 11. The drying method is not limited, and a method other than the oven 70 may be used.

[0037] The drying temperature can be set to a value above the melting point of the thermosetting resin A and below the reaction temperature. The reaction temperature is the temperature at which the calculated reaction rate first exceeds 0% during the temperature rise process in differential scanning calorimetry (DSC) measurement. 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 calorific value calculated from the temperature profile of the curing reaction obtained is defined as x [mJ / mg], which is the calorific value per unit mass of the exothermic peak of the curing reaction. Next, for the paper product for which the reaction rate is to be calculated, the calorific value y [mJ / mg] is calculated in the same manner, which is the calorific value per unit mass of the exothermic peak of the curing reaction. Using the above x and y, the reaction rate can be calculated using the following formula. (Formula) (reaction rate) = y / x × 100 [%]

[0038] Through the above steps, a sheet-like paper product 11 in a B-stage state is obtained.

[0039] [Step 2: Obtaining a papermaking mixture] Next, as shown in Figure 2(a), the paper product 11 and dispersant C are mixed using a grinder or the like to obtain a paper mixture 21. The paper mixture 21 refers to the paper product 11 in a state where the shape of the paper product 11 has been lost due to the dispersant C being mixed with the paper product 11. That is, in the paper product 11, the reinforcing fibers B are oriented in the in-plane direction and entangled with one another, resulting in a layered state. In this embodiment, therefore, by mixing the dispersant C with the paper product 11, the entanglement of the reinforcing fibers B can be untangled, and the reinforcing fibers B can be uniformly dispersed in the papermaking mixture 21 without breaking or bending. As a result, a decrease in mechanical strength due to the layered orientation of the reinforcing fibers B can be suppressed. Furthermore, in the molded product 41, the orientation of mechanical strength is reduced, allowing for greater freedom in designing the molded product 41. Furthermore, because the reinforcing fibers B are fibrous and difficult to disperse in the thermosetting resin A, the amount of reinforcing fibers B used has traditionally tended to be limited, but in this embodiment, a papermaking method is used, and a large amount of dispersion medium is used, so even if a large amount of reinforcing fibers B is used, they can be dispersed in the thermosetting resin A. As a result, in the molded body 41 of this embodiment, even higher mechanical strength can be obtained due to the reinforcing fibers B.

[0040] The mixing conditions are adjusted appropriately depending on the amount and length of the reinforcing fibers B, but mixing is preferably performed at 1,000 to 30,000 rpm for 10 seconds to 5 minutes, and more preferably at 1,200 to 20,000 rpm. To ensure adequate fluidity of the dispersant C, the temperature during mixing is preferably 10 to 30°C, and may be room temperature. This allows the reinforcing fibers B to be untangled and well dispersed without breaking or bending.

[0041] The blending amount of the dispersant C with respect to the paper article 11 is preferably 30 to 95 mass %, and more preferably 40 to 90 mass %. By setting the amount of dispersant C to be blended with the paper product 11 to be equal to or greater than the above-mentioned lower limit, it becomes easier to disperse the reinforcing fibers B and increase the mechanical strength of the reinforcing fibers B. On the other hand, by setting the amount of dispersant C to be blended with the paper product 11 to be equal to or less than the above-mentioned upper limit, it becomes easier to remove the dispersant C in the manufacturing process of the base product 31 described below, and manufacturing efficiency can be improved.

[0042] The viscosity (20° C.) of the paper-making mixture 21 is preferably 6000 to 12000 mPa·s, and more preferably 8000 to 10000 mPa·s. By setting the viscosity (20°C) of the papermaking mixture 21 to be equal to or greater than the above-mentioned lower limit, the reinforcing fibers B can be easily dispersed. As a result, the mechanical strength of the reinforcing fibers B in the molded body 41 can be easily increased. On the other hand, by setting the viscosity (20°C) of the papermaking mixture 21 to be equal to or less than the above-mentioned upper limit, workability is improved, and the dispersant C can be easily removed in the manufacturing process of the preform 31 described below.

[0043] The viscosity (20° C.) of the papermaking mixture 21 is measured using a B-type viscometer.

[0044] The dispersant C disentangles and disperses the reinforcing fibers B. It also imparts viscosity to the paper-making mixture 21. Dispersant C preferably contains one or more selected from the group consisting of polyacrylamide, polyalkylene oxide, polyacrylic acid and its salts, cellulose derivatives, polyvinyl alcohol, propylene glycol, alginic acid and its salts, and among these, polyacrylamide and polyalkylene oxide are preferred.

[0045] The alkylene oxide unit of the polyalkylene oxide is preferably an alkylene oxide having 2 to 4 carbon atoms, more preferably ethylene oxide having 2 carbon atoms or propylene oxide having 3 carbon atoms, and even more preferably ethylene oxide.

[0046] The weight average molecular weight of dispersant C is preferably 4 million to 15 million, more preferably 8 million to 10 million, from the viewpoint of improving dispersibility and imparting viscosity.

[0047] [Step 3: Step of obtaining a base body] Next, while removing the dispersant C from the papermaking mixture 21, the papermaking mixture 21 is pressed and molded to obtain a preform 31. The preform 31 is maintained in a B-stage state. First, as shown in Figure 2(b), the papermaking mixture 21 obtained in step 2 is poured into a predetermined lower mold 50. In this embodiment, the papermaking mixture 21 has fluidity and is in a gel state, so it can be poured into the lower mold 50 using a cylinder or the like. Furthermore, a known mold can be used, but the bottom of the lower mold 50 may be provided with a through-hole so that the dispersant C can be removed in a later step.

[0048] Next, as shown in Figure 2(c), pressure is applied to the papermaking mixture 21 from above the mold to squeeze out the dispersion medium containing dispersant C contained in the papermaking mixture 21, thereby preforming the mixture to obtain a preformed body 31. One method for removing the dispersant C is to use a lower mold 50 with multiple through-holes, as shown in Figure 2(c), and lower an upper mold 51 to compress the papermaking mixture 21, thereby discharging only the dispersant C to the outside through the through-holes. At this time, a wire mesh 52 with small openings may be placed in the lower mold 50 to cover the through-holes, so that the reinforcing fibers B in the papermaking mixture 21 are not also discharged along with the dispersant C. That is, pressure is applied to the papermaking mixture 21 from a certain direction to perform preforming. The pressure is preferably 0.01 to 1 MPa, more preferably 0.05 to 0.1 MPa. By applying a pressure equal to or greater than the above lower limit, the dispersant C can be easily removed and a preform 31 with appropriate hardness can be obtained. On the other hand, by applying a pressure equal to or less than the above upper limit, the reinforcing fibers B can be prevented from breaking or bending.

[0049] [Step 4: Step of obtaining a molded body] Thereafter, as shown in FIG. 2( d ), the obtained preform 31 is further heated and pressurized using an upper mold 51 to completely harden it, thereby obtaining a green body 41 . Curing conditions are determined appropriately depending on the raw materials used, etc., but it is preferable to heat the resin to a temperature below the melting point of the thermoplastic resin and above the curing temperature of the thermosetting resin. For example, when a phenolic resin is used, the temperature is preferably 150 to 200°C, more preferably 160 to 180°C. Furthermore, as for pressure conditions, the pressure is preferably 10 to 80 MPa, more preferably 30 to 60 MPa. Furthermore, the pressure application time is preferably about 1 to 10 minutes.

[0050] Alternatively, the base 31 may be removed from the mold, rotated so that pressure is applied from a direction different from the direction of pressure applied in step 3, and returned to the mold, after which heating and pressure application may be performed or the base 31 may be completely cured to obtain the molded product 41. This allows the reinforcing fibers B that were once oriented in the pressure direction in the base 31 to be randomized, thereby preventing a decrease in the mechanical strength of the molded product 41 due to the orientation of the reinforcing fibers B. From the viewpoint of workability, the degree of rotation is preferably 90° relative to the pressure direction in step 3, i.e., the direction of pressure applied to the base 31.

[0051] <Molded body> Fig. 3 is a perspective view showing an example of a molded body according to this embodiment, and Fig. 3(b) is an enlarged side view of Fig. 3(a). As shown in Fig. 3, in the molded body 41 of this embodiment, the reinforcing fibers B are entangled but randomly arranged, and therefore high mechanical strength is obtained. The content of the thermosetting resin is preferably 20 to 80% by volume relative to the total volume of the molded body 41. The molded article 41 of this embodiment is lightweight and has high mechanical strength, and therefore can be widely used in a variety of applications, such as construction materials, various transport machines such as automobiles and aircraft, and sporting goods.

[0052] The molded body 41 of this embodiment has excellent mechanical strength, and in particular has high bending strength. The bending strength can be measured by a known method, for example, using a measuring device such as "Tensilon" manufactured by A&D Co., Ltd. or "Autograph" manufactured by Shimadzu Corporation.

[0053] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. Below, examples of reference forms are given. 1. A step of dispersing a thermosetting resin and reinforcing fibers in a dispersion medium, and then removing the dispersion medium using a papermaking method to obtain a paper product; a step of mixing the paper product with a dispersant to obtain a paper-making mixture; a step of removing the dispersant from the papermaking mixture while pressing and molding the papermaking mixture to obtain a preform; a step of applying pressure and heat to harden the green body to obtain a molded body; A method for producing a molded body, comprising: 2. A method for producing the molded article described in 1., A method for producing a molded body, wherein the dispersant comprises one or more selected from the group consisting of polyacrylamide, polyalkylene oxide, polyacrylic acid and its salts, cellulose derivatives, polyvinyl alcohol, propylene glycol, and alginic acid and its salts. 3. A method for producing a molded article according to 1. or 2., A method for producing a molded article, wherein in the step of obtaining the papermaking mixture, the blending amount of the dispersant relative to the papermaking article is 30 to 95 mass %. 4. A method for producing a molded article according to any one of 1. to 3., A method for producing a molded body, wherein in the step of obtaining the preform, the papermaking mixture is pressurized at 0.1 MPa to 30 MPa. 5. A method for producing a molded article according to any one of 1. to 4., The method for producing a molded body, wherein the viscosity (20° C.) of the papermaking mixture obtained in the step of obtaining the papermaking mixture is 6000 to 12000 mPa·s. 6. A method for producing a molded article according to any one of 1. to 5., The method for producing a molded body, wherein in the step of obtaining the papermaking mixture, the materials are mixed at 1,000 to 30,000 rpm for 10 seconds to 5 minutes. 7. A method for producing a molded article according to any one of 1. to 6., In the step of obtaining the basic form, The method for producing a molded body includes: pouring the papermaking mixture into a mold; and discharging the dispersant from the papermaking mixture through through holes formed in the mold. 8. A method for producing a molded article according to any one of 1. to 7., A method for producing a molded article, wherein the content of the reinforcing fibers is 30 to 60% by volume of the paper article. 9. A method for producing a molded article according to any one of 1. to 8., A method for producing a molded article, wherein 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. 10. A method for producing a molded article according to any one of 1. to 9., A method for producing a molded article, wherein the reinforcing fibers comprise 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, polyparaphenylenebenzoxazole fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, and ethylene vinyl alcohol fibers. 11. A method for producing a molded article according to any one of 1. to 10., The method for producing a molded article, wherein the content of the thermosetting resin is 20 to 80% by volume based on the total amount of the molded article. [Example]

[0054] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0055] Example 1 [Step 1] Making the paper body 50 parts by weight of a thermosetting resin (resol-type phenolic resin, "Sumilite Resin PR-51723" manufactured by Sumitomo Bakelite Co., Ltd.), 40 parts by weight of reinforcing fiber (recycled carbon, average fiber length 6 mm), and 10 parts by weight of pulp fiber (aramid microfiber, "Tiara KY-400S" manufactured by Daicel FineChem Co., Ltd., average fiber length 500-600 μm) were added to water as a dispersion medium, and the mixture was stirred for 20 minutes to obtain a slurry with a solids concentration of 0.15 wt%. To the resulting slurry, a poly(meth)acrylic acid ester emulsion ("Himoc DR-9300" manufactured by Hymo Co., Ltd.) prepared in advance was added so that the amount was 300 ppm relative to the solid content in the slurry, and the solid content in the slurry was coagulated. 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 under a pressure of 3 MPa for dehydration. The dehydrated aggregates were then dried at 70°C for 3 hours to obtain a sheet-like papermaking product (size 300 mm × 300 mm, thickness 5 mm).

[0056] [Step 2] Preparation of papermaking mixture One part by mass of the resulting sheet-like paper product was mixed with 99 parts by mass of dispersant 1 (polyacrylamide "Product name Pamol" manufactured by Meisei Chemical Industry Co., Ltd., weight average molecular weight 10 to 15 million) under the following conditions to obtain a papermaking mixture. The viscosity of the resulting papermaking mixture (at 20°C) was measured and found to be approximately 8000 mPa s. ·Mixing conditions Mill: Labo Millser LM-PLUS (Osaka Chemical) Crushing cutter: PN-J56 Temperature: normal temperature Grinding container: Micron container PN-J55 Grinding speed: 20,000 rpm Grinding time: 1 min

[0057] [Step 3] Preparation of the base body The obtained papermaking mixture was placed in a mold, and by cold pressure preforming, dispersant 1 was expelled downward through the through holes in the lower mold and removed, while pressure was applied in the direction of gravity under the following conditions to obtain an approximately rectangular parallelepiped base body. ·conditions Pressure: 0.1 MPa, Time: 1 minute

[0058] [Step 4] Preparation of the molded body The obtained green body was removed from the mold, rotated 90° relative to the direction of gravity, and then placed back in the mold and cured under the following conditions. ·Curing conditions Temperature: 180℃, mold clamping pressure: 30MPa, time: 10 minutes

[0059] <Example 2> A molded body was obtained in the same manner as in Example 1, except that in step 4, the green body was cured as it was without being rotated.

[0060] <Reference example 1> The papermaking product obtained in step 1 of Example 1 was cured under the same conditions as in step 4 of Example 1 to obtain a molded product.

[0061] The resulting molded body was subjected to the following measurements and observations, and the results are shown in Table 1. [measurement] Bending strength: Bending stress was applied to the molded body in a direction perpendicular to the thickness direction of the molded body (the direction of pressure applied during curing), and the results were calculated. The test machine was manufactured by A&D. A Tensilon was used. Specifically, when the bending moment measured using a test piece with width b [mm] and thickness h [mm] was M [kg·cm], the bending strength σf [MPa] was calculated from the relationship σf = 9.8 × 6 × 10 × M / (bh2).

[0062] [observation] The cross section of each molded body in the direction of pressure during curing was observed under an optical microscope to observe the orientation of the reinforcing fibers. As a result of the observation, the orientation of the reinforcing fibers was not observed in the molded bodies of Examples 1 and 2, and the cracks after the bending test were dispersed and no progression of the cracks was observed. On the other hand, in the molded body of Reference Example 1, the cracks after the bending test progressed and cracks almost parallel to the horizontal direction were observed.

[0063] [Table 1] [Explanation of symbols]

[0064] 11 Papermaking 21 Papermaking mixture 31 Elementary Form 41 Molded body 50 Lower mold 51 Upper mold 52 Wire Mesh 60 mesh 70 Oven A Thermosetting resin B. Reinforced fiber C. Dispersant

Claims

1. a step of dispersing a thermosetting resin and reinforcing fibers in a dispersion medium, and then removing the dispersion medium using a papermaking method to obtain a paper product; a step of mixing the paper product with a dispersant and untangling the reinforcing fibers so as to eliminate the shape of the paper product, thereby obtaining a paper mixture comprising the paper product and the dispersant; a step of removing the dispersant from the papermaking mixture while pressing and molding the papermaking mixture to obtain a preform; a step of applying pressure and heat to harden the green body to obtain a molded body; A method for producing a molded body, comprising:

2. A method for producing the molded article according to claim 1, A method for producing a molded body, wherein the dispersant comprises one or more selected from the group consisting of polyacrylamide, polyalkylene oxide, polyacrylic acid and its salts, cellulose derivatives, polyvinyl alcohol, propylene glycol, and alginic acid and its salts.

3. A method for producing the molded article according to claim 1 or 2, A method for producing a molded article, wherein in the step of obtaining the papermaking mixture, the blending amount of the dispersant relative to the papermaking article is 30 to 95 mass %.

4. A method for producing the molded body according to any one of claims 1 to 3, In the step of obtaining the preform, the papermaking mixture is pressed at a pressure of 0.1 MPa to 30 MPa.

5. A method for producing the molded body according to any one of claims 1 to 4, The viscosity (20°C) of the papermaking mixture obtained in the step of obtaining the papermaking mixture is 6000 to 12000 mPa·s.

6. A method for producing the molded body according to any one of claims 1 to 5, In the step of obtaining the papermaking mixture, the materials are mixed at 1,000 to 30,000 rpm for 10 seconds to 5 minutes.

7. A method for producing the molded body according to any one of claims 1 to 6, In the step of obtaining the basic form, The method for producing a molded body includes: pouring the papermaking mixture into a mold; and discharging the dispersant from the papermaking mixture through through holes formed in the mold.

8. A method for producing the molded body according to any one of claims 1 to 7, The method for producing a molded body, wherein the content of the reinforcing fibers is 30 to 60 volume % of the papermaking body.

9. A method for producing the molded body according to any one of claims 1 to 8, A method for producing a molded article, wherein 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.

10. A method for producing the molded body according to any one of claims 1 to 9, The method for producing a molded article, wherein the reinforcing fibers comprise 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.

11. A method for producing the molded body according to any one of claims 1 to 10, The method for producing a molded body, wherein the content of the thermosetting resin is 20 to 80% by volume based on the total amount of the molded body.

Images