Laminate

Abstract

To reduce occurrence of damage to a laminate.SOLUTION: A laminate 100 of the present invention includes: a fiber-reinforced plastic layer 11 including continuous fibers 10 oriented in one direction; and a sheet-making layer 12, the fiber-reinforced plastic layer and the sheet-making layer being stacked. In the laminate 100, the fiber-reinforced plastic layer 11 has an end surface 10a at which continuity of the continuous fibers 10 terminates. The sheet-making layer 12 is provided at a position adjacent to the end surface 10a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate. [Background technology]

[0002] Fiber-reinforced plastics (FRPs), composite materials made by adding fibers to plastics to improve their strength, are known as materials that combine high strength and light weight. In particular, carbon fiber-reinforced plastics (CFRPs), which use carbon fiber as the fiber, can be designed to be lightweight, high strength, and high rigidity, and also have excellent electrical properties and corrosion resistance, so development is underway for a variety of applications. For example, they are widely used as a replacement for metal materials in aerospace structures, structural components for automobiles and motorcycles, large industrial machine parts, sporting goods, and more. Such CFRP is made by impregnating carbon fibers with thermosetting resin or the like and processing them into a plate-shaped material called prepreg. Multiple sheets of such prepreg are stacked and heated and pressed together to form a hardened structure.

[0003] However, because conventional CFRP is made by stacking multiple prepregs and then heating and pressing them together to harden, external impact can cause separation at the interfaces between the prepregs or between the carbon fibers and resin that make up the prepregs, resulting in delamination.Patent Document 1 therefore describes a manufacturing method in which a thin resin film containing carbon nanotubes is inserted between the prepreg layers in the process of laminating the prepregs, in order to prevent such delamination. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-16030 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a conventional laminate such as that disclosed in Patent Document 1 is processed, regions where cracks are likely to occur tend to occur due to breakage of the reinforcing fibers, etc. The inventors therefore conducted extensive research to prevent the propagation of cracks that occur from causing significant damage to the laminate, and discovered that by placing a papermaking sheet in contact with the cut parts of the reinforcing fibers, even if cracks occur, the papermaking sheet can prevent the cracks from propagating, thereby preventing breakage and damage to the laminate, and thus completed the present invention. [Means for solving the problem]

[0006] According to the present invention, the following laminate is provided.

[0007] [1] A laminate in which a fiber-reinforced plastic layer having continuous fibers oriented in one direction and a papermaking layer are laminated, Within the laminate, the fiber-reinforced plastic layer has an end surface where the continuity of the continuous fibers is interrupted, A laminate in which the papermaking layer is provided at a position adjacent to the end surface. [2] The laminate according to [1], The end surface is composed of a plurality of adjacent continuous fibers. [3] The laminate according to [1] or [2], A laminate in which the thickness (mm) of the papermaking layer is 5 to 35% of the thickness (mm) of the fiber-reinforced plastic layer. [4] The laminate according to any one of [1] to [3], The end surface is covered with a resin portion having a relatively larger amount of resin than the fiber-reinforced plastic layer and the papermaking layer. [5] The laminate according to [4], The resin portion is located at a step caused by a difference in surface area of ​​the laminated fiber-reinforced plastic layers. [6] The laminate according to [4] or [5], In a plan view of the laminate, the resin portion is surrounded by the adjacent papermaking layer. [7] The laminate according to any one of [4] to [6], A laminate, wherein the papermaking layers are provided so as to sandwich the resin portion in a layer direction of the laminate. [8] The laminate according to any one of [4] to [7], The resin portion includes at least one of a resin constituting the fiber-reinforced plastic layer and a resin constituting the papermaking layer. [9] The laminate according to any one of [1] to [8], The fiber-reinforced plastic layer comprises one or two fibers selected from glass fiber and carbon fiber.

[10] The laminate according to any one of [1] to [9], The laminate has one or more selected from a bent portion, a stepped portion, an inclined portion, and a combination thereof in its plane.

[11] The laminate according to any one of [1] to

[10] , The laminate has a functional hole, and the end face is exposed to an inner wall of the functional hole.

[12] The laminate according to any one of [1] to

[11] , The laminate, wherein the papermaking layer contains reinforcing short fibers.

[13] The laminate according to

[12] , The reinforcing short 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.

[14] The laminate according to any one of [1] to

[13] , The laminate, wherein the papermaking layer contains at least one of a thermosetting resin and a thermoplastic resin. [Effects of the Invention]

[0008] According to the present invention, damage to the laminate can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a laminate of the present embodiment. [Figure 2] FIG. 10 is a perspective view showing an example of a modified example of the laminate of the present embodiment. [Figure 3] FIG. 10 is a perspective view showing an example of a modified example of the laminate of the present embodiment. [Figure 4] FIG. 2 is a schematic diagram showing the layer structure of a laminate produced in an example. [Figure 5] FIG. 2 is a photograph showing the side surface of the laminate of Example 1 observed during a tensile test. [Figure 6] FIG. 1 is a photograph showing the side surface of the laminate of Comparative Example 1 during a tensile test. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this specification, unless otherwise specified, the expression "a to b" in the description of a numerical range means from a to b. For example, "1 to 5 mass %" means "1 mass % to 5 mass %."

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all drawings, similar components are denoted by similar reference numerals, and their explanations are omitted where appropriate. To avoid complication, when there are multiple identical components in the same drawing, only one of them may be denoted by a reference numeral, and not all of them may be denoted by a reference numeral. Furthermore, the drawings are for illustrative purposes only, and the shapes and dimensional ratios of the components in the drawings do not necessarily correspond to the actual products. The drawings are merely examples, and the shape, number, length, height, area, dimensional ratio, arrangement, orientation, etc. of each member are merely examples and are not intended to be limiting.

[0012] It should be noted that "covering" and "coating" are not limited to continuous cases, and may also refer to partial discontinuity.

[0013] In the present embodiment, the thickness of each of the laminate, fiber-reinforced plastic layer, and papermaking layer represents the average value per layer.

[0014] <Carbon fiber reinforced plastic laminate> As shown in Figure 1, the laminate 100 of this embodiment is a laminate 100 formed by laminating a fiber-reinforced plastic layer 11 having continuous fibers 10 oriented in one direction and a papermaking layer 12, and within the laminate 100, the fiber-reinforced plastic layer 11 has an end surface 10a where the continuity of the continuous fibers 10 is interrupted, and the papermaking layer 12 is located adjacent to the end surface 10a. In this embodiment, the laminate 100 also has a resin portion 30 that covers the end faces 10a where the continuity of the continuous fibers 10 is interrupted.

[0015] This can prevent damage and breakage of the laminate 100. The reason for this is not clear in detail, but is thought to be as follows. First, the strength of the region where the continuity of the continuous fibers 10 in the fiber-reinforced plastic layer 11 is interrupted tends to be lower than the surrounding area. Furthermore, the interruption of the continuity of the continuous fibers 10 creates voids inside the laminate 100, and the resin contained in the fiber-reinforced plastic layer 11 tends to seep into these voids and form resin pools. Therefore, the area around the end surface 10a where the continuity of the continuous fibers 10 is interrupted is prone to cracking. Therefore, in the laminate 10 of this embodiment, the papermaking layer 12 is provided adjacent to the end face 10a, so that the papermaking layer 12 can suppress the propagation of cracks. That is, since the papermaking layer 12 has lower strength than the fiber-reinforced plastic layer 11, it is believed that a crack that occurs in the laminate 100 will first propagate to the papermaking layer 12. Because the papermaking layer 12 is formed from high-density short fibers, it is believed that even if a crack does occur, the short fibers can suppress the propagation of the crack. As a result, it is believed that the propagation of the crack to the fiber-reinforced plastic layer 11 is suppressed, and damage to the laminate 100 itself can be suppressed. Furthermore, since the papermaking layer 12 is adjacent to the resin pool, the resin penetrates into the papermaking layer 12, improving the adhesive strength, which is thought to improve the interlayer strength of the entire laminate 100 and suppress damage.

[0016] Furthermore, in the laminate 100, the fiber-reinforced plastic layer 11 and the papermaking layer 12 each contain resin, which allows the resins to penetrate each other and form a strong bond, thereby improving the interlayer strength of the entire laminate 100 and suppressing damage. For example, by controlling the conditions of the heat and pressure treatment when the fiber reinforced plastic layer 11 and the papermaking layer 12 are laminated together, at least a portion of the papermaking layer 12 can be impregnated into the fiber reinforced plastic layer 11 .

[0017] In this embodiment, the fiber reinforced plastic layer 11 and the papermaking layer 12 may be laminated, and the number of layers laminated is not particularly limited. Furthermore, when the fiber-reinforced plastic layer 11 has an end surface 10a inside the laminate 100 where the continuity of the continuous fibers 10 is interrupted, this means that the end surface 10a is not exposed on the outer surface of the laminate 100, and if the laminate 100 has a functional hole inside, the end surface 10a may be exposed on the inner wall of the functional hole. The continuity of the continuous fibers 10 being interrupted means, when focusing on the fiber-reinforced plastic layer 11, a case in which the length of one continuous fiber 10 is shorter than the length of another continuous fiber 10, or, when comparing fiber-reinforced plastic layers 11, a case in which the length of the continuous fibers 10 constituting one fiber-reinforced plastic layer 11 is shorter than the length of the continuous fibers 10 constituting the other fiber-reinforced plastic layer 11. The number and positions of the end faces 10a are not particularly limited, and the end faces 10a may be continuous, formed by a plurality of continuous fibers, or there may be a plurality of continuous end faces 10a. The position of the papermaking layer 12 adjacent to the end face 10a means that the papermaking layer 12 is laminated so as to be in contact with the fiber-reinforced plastic layer 11 comprising the continuous fibers 10 having the end face 10a.

[0018] Each component of the laminate 100 will be described below.

[0019] [Fiber reinforced plastic layer] The fiber reinforced plastic layer 11 of this embodiment is a sheet-like member in which a plurality of continuous fibers 10 are arranged and which is impregnated with a resin 15. In FIG. 1, in the laminate 100, the continuous fibers 10 are oriented in the length direction of the fibers, and the continuous fibers 10 of the plurality of fiber-reinforced plastic layers 11 are oriented in the same direction as each other.

[0020] The continuous fibers 10 may be continuous from one end to the other end of the fiber-reinforced plastic layer 11, or may be partially discontinuous, and can be designed appropriately depending on the application and processing of the laminate 100. For example, if the length of the laminate 100 in the direction in which the continuous fibers 10 are oriented is 100, the length of the continuous fibers 10 may be 50 to 100%, or 80 to 100%.

[0021] 1 shows an example in which two continuous fibers 10 stacked one above the other inside the laminate 100 are discontinuous, and two continuous end faces 10a are adjacent to each other above and below. In other words, inside the laminate 100, the discontinuous continuous fibers 10 adjacent to each other above and below are stacked so that their end faces are aligned.

[0022] The content of the continuous fibers 10 relative to all the fibers constituting the fiber-reinforced plastic layer 11 is preferably 50 to 100% by volume, more preferably 60 to 99% by volume, and even more preferably 70 to 98% by volume. By setting the content of the continuous fibers 10 to the above lower limit or more, it is possible to improve the desired mechanical strength of the laminate 100. On the other hand, by setting the content to the above upper limit or less, it is possible to use reinforcing fibers other than the continuous fibers 10, thereby widening the design possibilities.

[0023] The fiber diameter of the continuous fibers 10 is not particularly limited, but from the viewpoint of suppressing damage to the laminate 100 and obtaining good mechanical strength and processability, it is preferably 1 to 20 μm, more preferably 2 to 15 μm.

[0024] The fiber diameter and fiber length of the continuous fibers 10 can be measured by observing them with an electron microscope, for example.

[0025] There are no particular limitations on the resin 15 that constitutes the fiber reinforced plastic layer 11, and any known resin used in fiber reinforced plastics (FRP) can be used. Examples of resin 15 that can be used include known thermosetting resins such as epoxy resin, phenol resin, unsaturated polyester resin, vinyl ester resin, cyanate resin, and polyimide resin.

[0026] [Resin part 30] 1, in this embodiment, the end surface 10a is covered with a resin portion 30 having a relatively larger amount of resin than the fiber-reinforced plastic layer 11 and the papermaking layer 12. That is, within the laminate 100, the regions where the continuous fibers 10 are discontinuous are filled with the resin portion 30.

[0027] The resin portion 30 is made of resin and does not substantially contain inorganic fillers, reinforcing fibers, etc. The resin concentration of the resin portion 30 is higher than the resin concentration of the fiber-reinforced plastic layer 11 and the resin concentration of the papermaking layer 12. Therefore, the resin portion 30 has lower mechanical properties than the fiber-reinforced plastic layer 11 and the papermaking layer 12, and cracks are more likely to occur due to stress concentration in the resin portion 30 region.

[0028] The resin portion 30 may be formed by a portion of the resin 15 contained in the fiber-reinforced plastic layer 11 described later and a portion of the resin contained in the papermaking layer 12 seeping into the area (also called the void) where the continuous fibers 10 are discontinuous, or may be a resin provided to cover the end face 10a (i.e., to fill the void). In this embodiment, the resin portion 30 preferably contains at least one of the resin 15 constituting the fiber-reinforced plastic layer 11 and the resin constituting the papermaking layer 12, in order to improve the interlayer adhesion of the laminate 100.

[0029] The position of the resin part 30 in the laminate 100 is not particularly limited, but may be partly exposed inside the laminate 100. Furthermore, if the laminate 100 has functional holes, which will be described later, the resin part 30 may be exposed on the inner wall of the functional holes.

[0030] The resin portion 30 is preferably contained within the largest area of ​​the fiber reinforced plastic layer 11 in the plane of the laminate 100, and more preferably surrounded by the adjacent papermaking layer 12. Furthermore, in a cross-sectional view of the laminate 100, the resin part 30 is preferably thinner than the fiber-reinforced plastic layer 11, and more preferably has the papermaking layers 12 positioned above and below it. That is, it is more preferable that the papermaking layers 12 are provided so as to sandwich the resin part 30 in the layer direction of the laminate 100.

[0031] The resin portion 30 may be located at a step caused by a difference in surface area of ​​the fiber reinforced plastic layers 11 laminated in the laminate 100, for example. That is, in order to process the flat laminate 100 to provide bends, steps, slopes, etc., the fiber reinforced plastic layers 11 are bent or cut, and therefore the surface areas of the plurality of fiber reinforced plastic layers 11 differ from one another. As a result, steps are generated due to the difference in surface area of ​​the fiber reinforced plastic layers 11, and resin may penetrate into the steps to fill them, thereby forming the resin portion 30.

[0032] [Paper forming layer] The papermaking layer 12 of this embodiment is provided adjacent to the end face 10a where the continuity of the continuous fibers 10 is interrupted. This prevents cracks that occur around the end face 10a from progressing into the laminate 100 and damaging the laminate 100.

[0033] The thickness (mm) of the papermaking layer 12 in the laminate 100 is preferably 5 to 35% of the thickness (mm) of the fiber-reinforced plastic layer 11, more preferably 8 to 32%, even more preferably 12 to 30%, and especially preferably 15 to 29%. By setting the thickness (mm) of the papermaking layer 12 to the above lower limit or more, the adhesion between the papermaking layer 12 and the fiber-reinforced plastic layer 11 is improved, while the progression of cracks is suppressed, and damage to the laminate 100 is likely to be reduced. On the other hand, by setting the thickness (mm) of the papermaking layer 12 to the above upper limit or less, the mechanical strength of the fiber-reinforced plastic layer 11 is effectively exerted, and the desired mechanical strength of the laminate 100 is easily obtained.

[0034] The thickness of the papermaking layer 12 in this embodiment is preferably 0.05 to 0.8 mm, and more preferably 0.1 to 0.3 mm. By making the thickness of the papermaking layer 12 equal to or greater than the above-mentioned lower limit, the toughness between the layers can be increased. On the other hand, by making the thickness of the papermaking layer 12 equal to or less than the above-mentioned upper limit, good adhesion between the layers can be maintained while preventing delamination.

[0035] The thickness of the papermaking layer 12 can be obtained by observing the cross section of the laminate 100, measuring the distance from the outer edge of the continuous fibers 10 in one fiber-reinforced plastic layer 11 to the outer edge of the continuous fibers 10 in the other fiber-reinforced plastic layer 11 multiple times, and calculating the average value. The thickness of the papermaking layer 12 can be adjusted by adjusting the content of reinforcing short fibers contained in the papermaking layer 12, etc.

[0036] The in-plane size of the papermaking layer 12 is preferably such that it covers the resin portion 30, and is preferably 5 to 30 times larger than the area of ​​the resin portion 30. By making the in-plane size of the papermaking layer 12 equal to or greater than the lower limit, initial delamination can be suppressed while also effectively suppressing interlayer delamination. On the other hand, by making the in-plane size of the papermaking layer 12 equal to or less than the upper limit, interlayer delamination and initial delamination can be suppressed in a balanced manner.

[0037] The papermaking layer 12 is obtained by dispersing the reinforcing short fibers in a large amount of solvent and then papermaking the reinforcing short fibers, depositing them in a layer while uniformly entangling them. Furthermore, by papermaking, the proportion of the reinforcing short fibers can be increased and they can be more uniformly entangled. It is believed that this entanglement of the reinforcing short fibers can suppress the propagation of cracks.

[0038] (short fiber reinforcement) Examples of reinforcing short fibers include one or more types 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. Among these, metal fibers, carbon fibers, and glass fibers are preferred from the viewpoint of obtaining high interlaminar fracture toughness.

[0039] The content of the reinforcing short fibers is preferably adjusted appropriately depending on the total amount including the content of any inorganic filler described below. The total content of the reinforcing short fibers and inorganic filler is preferably 50 to 95% by volume, more preferably 60 to 90% by volume, and even more preferably 70 to 80% by volume, based on the total volume of the papermaking layer 12. By setting the total content of the reinforcing short fibers and inorganic filler to at least the above lower limit, it is possible to suppress the propagation of cracks while maintaining the overall mechanical strength of the papermaking layer 12. On the other hand, by setting the total content of the reinforcing short fibers and inorganic filler to at most the above upper limit, it is possible to maintain good moldability of the laminate 100.

[0040] The papermaking layer 12 of this embodiment can suppress the progression of cracks by containing reinforcing short fibers, but in addition to the reinforcing short fibers, it may also contain other components such as resins such as thermoplastic resins and thermosetting resins, pulp fibers, inorganic fillers, and coagulants, depending on the purpose.

[0041] (resin) The papermaking layer 12 of this embodiment may contain a resin. When the papermaking layer 12 contains a resin, the generation of voids in the papermaking layer 12 can be suppressed. Resins include thermoplastic resins and thermosetting resins.

[0042] ·Thermoplastic resin Examples of the thermoplastic resin used in the papermaking layer 12 include α-olefin resins and copolymers using α-olefins, polyester resins, and polystyrene resins. Examples of α-olefin resins and copolymers using α-olefins include polyethylene and polypropylene. Among these, polyethylene is preferred, and high-density polyethylene (HDPE) is more preferred. When the papermaking layer 12 contains high-density polyethylene (HDPE), the propagation of cracks in the laminate 100 can be suppressed.

[0043] The polyester resin may be one or more selected from polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate resin (PTT), and the like.

[0044] ·Thermosetting resin The thermosetting resin used in the papermaking layer 12 may be a phenolic resin, an epoxy resin, a melamine resin, a polyurethane, or an unsaturated polyester resin. The thermosetting resin may be one or a combination of two or more of the above-mentioned specific examples. Of these, phenolic resin and epoxy resin are particularly preferred.

[0045] Specific examples of the phenolic resin include novolac-type phenolic resins, resol-type phenolic resins, aryl alkylene-type phenolic resins, etc. 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.

[0046] 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 epoxy resins, 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 triphenolmethane-type epoxy resins and alkyl-modified triphenolmethane-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. Examples of suitable epoxy resins include phenol aralkyl epoxy resins such as aryl epoxy resins (biphenyl aralkyl epoxy resins) and naphthol aralkyl epoxy resins having a biphenylene skeleton; naphthol epoxy resins such as dihydroxynaphthalene 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 epoxy resins such as dicyclopentadiene-modified phenol epoxy resins; brominated epoxy resins such as brominated bisphenol A and brominated phenol novolac; and tris(hydroxyphenyl)methane epoxy resins. These epoxy resins may be used singly or in combination.

[0047] (pulp fiber) The papermaking layer 12 according to this embodiment may contain pulp fibers in order to improve the handling properties of the papermaking layer 12 during the manufacturing process. Pulp fibers are not particularly limited, but examples 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 organic fibers such as para-type wholly aromatic polyamide fibers and copolymers thereof, aromatic polyester fibers, polybenzazole fibers, meta-type aramid fibers and copolymers thereof, acrylic fibers, acrylonitrile fibers, polyimide fibers, and polyamide fibers. Of the above specific examples, one or a combination of two or more can be used as the pulp fiber.

[0048] (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 these, from the viewpoint of easily improving the balance between mechanical strength and moldability of the papermaking layer 12 as a whole, fused silica is preferred, clay is more preferred, and a mixture of these is also acceptable.

[0049] The inorganic filler may be surface-treated. For example, the surface may be treated with a coupling agent such as a silane coupling agent. This can prevent the inorganic filler from aggregating and improve 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, per 100 parts by weight of the inorganic filler.

[0050] 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; needle-like, fibrous, and plate-like shapes. When the inorganic filler is granular, the average particle size is preferably 0.1 to 100 μm, more preferably 0.1 to 50 μm, and even more preferably 0.1 to 20 μm. By setting the average particle size of the inorganic filler to the above lower limit or more, it is possible to obtain good dispersibility and improve mechanical strength, while by setting the average particle size of the inorganic filler to the above upper limit or less, it is possible to maintain dispersibility and stabilize mechanical strength. When a fibrous inorganic filler is selected as the material, it is preferable to shorten the fiber length by cutting or the like. 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, its cross-sectional diameter is preferably 0.1 to 20 μm.

[0051] The average particle size of the inorganic filler is the particle size (D50) at cumulative 50% of the volume-based particle size distribution, and can be measured using a commercially available laser particle size distribution analyzer (for example, SALD-7000 manufactured by Shimadzu Corporation).

[0052] (flocculant) The papermaking layer 12 according to this embodiment may contain, for example, a flocculant, which allows any resin component and the reinforcing short fibers to be agglomerated onto the flock. Specific examples of flocculants that can be used include 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, and polyethylene oxide. These polymer flocculants may be used alone or in combination with two or more. Furthermore, the polymer structure, molecular weight, and amount of functional groups such as hydroxyl groups and ionic groups can be used as polymer flocculants without particular limitations depending on the required properties.

[0053] (Other ingredients) The papermaking layer 12 according to this embodiment may further contain, for example, papermaking agents, ion exchange agents, flocculants, conductivity imparting agents, flame retardants, flame retardant assistants, pigments, dyes, lubricants, release agents, compatibilizers, dispersants, 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.

[0054] [Manufacturing method of papermaking layer 12] The papermaking layer 12 of this embodiment can be obtained by a known method, for example, by the following method.

[0055] First, fibers such as reinforcing short fibers and optional components such as the resin components for the papermaking layer 12 (excluding the flocculant) are dispersed in a dispersion medium to prepare a slurry.

[0056] The above resin components may be added to the dispersion medium alone, or may be added to the dispersion medium as a resin mixture containing a curing agent and a curing accelerator, or both may be added together.

[0057] The resin kneaded product can be, for example, a thermosetting resin composition prepared by mixing a thermosetting resin, a curing agent, a curing accelerator, etc. In this case, the thermosetting resin composition is preferably solid at 25°C, and more preferably in the form of powder, powder, or granules.

[0058] Next, a flocculating agent is added to the dispersion liquid as needed to form an aggregate. Note that if the reinforcing short fibers and the resin component are sufficiently aggregated to form an aggregate, the aggregation step may not be carried out. The slurry is then placed in a container with a mesh bottom to separate the dispersion medium from the aggregates, leaving the aggregates on the mesh to obtain a flat sheet-shaped aggregate. The thickness of the sheet can be adjusted by adjusting the amounts of the materials in the material slurry or by preparing a new slurry and performing the separation process. The dispersion medium is then removed by dehydration pressing and drying, and if a thermosetting resin is included, a pre-papermaking layer in a B-stage state can be obtained.

[0059] The pre-papermaking layer is later heated and pressurized together with the fiber-reinforced plastic layer 11, and if it contains a thermosetting resin, it is completely cured to become the papermaking layer 12 that constitutes the laminate 100. The thickness of the pre-papermaking layer can be adjusted as appropriate by changing the proportion of reinforcing short fibers, the proportion of inorganic filler, etc.

[0060] Although the laminate 100 has been described above with reference to Fig. 1, the present invention can also employ various other configurations. Modifications of the present invention will be described below.

[0061] For example, in this embodiment, Figure 1 shows a case where four fiber-reinforced plastic layers 11, each having five continuous fibers 10 arranged in a plane, are stacked together, but the number, length, size, and arrangement of the continuous fibers 10 that make up the fiber-reinforced plastic layers 11 are not limited to this.

[0062] Furthermore, the thickness, shape, number of layers, etc. of the fiber reinforced plastic layers 11 in the laminate 100 are not limited to those described above, and a plurality of fiber reinforced plastic layers 11 of different shapes and thicknesses may be laminated.

[0063] Furthermore, Figure 1 shows a case in which the papermaking layers 12 are arranged so as to sandwich the end face 10a where the continuity of the continuous fibers 10 is interrupted from the vertical direction, but the position, shape, size, number, orientation, etc. of the papermaking layers 12 are not limited to this. The position, shape, size, etc. of the end surface 10a where the continuity of the continuous fiber 10 is interrupted and the resin portion 30 are not limited to those described above.

[0064] There is no particular limitation on the shape of the laminate 100. While Fig. 1 shows an example in which the laminate 100 is a flat plate, the laminate 100 may have one or more selected from a bent portion, a stepped portion, an inclined portion, and a combination thereof within the plane.

[0065] For example, Fig. 2 shows an example in which the laminate 101 has an inclined portion. That is, a part of the flat laminate 101 is inclined. 2, inside the laminate 101, the fiber-reinforced plastic layer 11 has an end surface 10a where the continuity of the continuous fibers 10 is interrupted, and the papermaking layer 12 is provided at a position adjacent to the end surface 10a. Furthermore, because the continuity of the continuous fibers 10 in each fiber-reinforced plastic layer 11 is interrupted, a resin portion 30 is located at a step caused by a difference in surface area of ​​the fiber-reinforced plastic layer 11. Even if a crack occurs in the laminate 101 due to the end face 10a, the papermaking layer 12 can suppress the crack from growing, and damage to the laminate 101 can be reduced.

[0066] Furthermore, as shown in Figure 3, the continuity of the continuous fibers 10 in each fiber-reinforced plastic layer 11 may be interrupted to follow the inclined portion of the laminate 102, and the resin portion 30 may be located at a step caused by a difference in surface area of ​​the fiber-reinforced plastic layer 11.

[0067] The laminate 100 may further have a functional hole. In this case, the end face 10a is exposed to the inner wall of the functional hole, and the papermaking layer 12 is provided in a position adjacent to the end face 10a. In this case, even if a crack occurs due to the end face 10a, the papermaking layer 12 can suppress the crack from progressing, thereby reducing damage to the laminate 100.

[0068] The functional holes are holes intended to provide a desired function, and are not particularly limited in size, shape, position, orientation, etc. For example, the functional holes may be provided in the stacking direction of the laminate 100. Examples of functional holes include grooves and holes for fasteners such as bolt holes, rivet holes, and screw holes; openings for ventilation, air supply, and ventilation; windows for lighting, communication, etc.; and grooves and holes for attaching devices.

[0069] Furthermore, in the laminate 100, the plurality of fiber-reinforced plastic layers 11 may be laminated so that the orientation directions of the continuous fibers 10 differ from one another. For example, the plurality of fiber-reinforced plastic layers 11 may be alternately laminated by rotating them by 90 degrees so that the extending directions of the continuous fibers 10 are perpendicular to one another. This reduces the anisotropy of the mechanical strength of the laminate 10 due to the orientation direction of the continuous fibers 10.

[0070] [Application] The use of the laminate 100 is not particularly limited. Examples of uses include automobiles, aircraft, railroad vehicles, ships, office equipment, general-purpose machines, household electrical appliances, electrical equipment, various housings, structural and mechanical parts, etc. Among these, the laminate 100 is suitable for transportation and conveyance machinery such as automobiles, aircraft, railroad vehicles, ships, etc., which require both high levels of lightness and strength, but of course, other uses are also not excluded.

[0071] <Method of manufacturing laminate> An example of a method for manufacturing the laminate 100 of this embodiment will be described. First, the fiber reinforced plastic layer 11 and the pre-sheet-formed layer are prepared. The fiber reinforced plastic layer 11 and the pre-sheet-formed layer can be obtained by a known method.

[0072] Next, a pre-papermaking layer is placed at any position so as to be interposed between multiple fiber-reinforced plastic layers 11, and the fiber-reinforced plastic layers 11 and the pre-papermaking layers are stacked together and heated and pressurized from above and below to integrate them, thereby obtaining a laminated structure of fiber-reinforced plastic layers 11 and papermaking layers 12.

[0073] For example, the heating and pressurizing method is not particularly limited, but includes methods using press molding and autoclave. The heating and pressurizing conditions are preferably adjusted appropriately depending on the fiber-reinforced plastic layer 11, but are preferably, for example, 130 to 180°C, 0.4 to 40 MPa, and 2 to 4 hours. When an autoclave is used as the heating and pressurizing method, the pressure is preferably 0.4 to 1 MPa.

[0074] During this process, the resin components present between the continuous fibers 10 in the fiber-reinforced plastic layer 11 and any resin components contained in the pre-papermaking layer are melted or softened and then hardened, thereby integrating the fiber-reinforced plastic layer 11 and the papermaking layer 12. The pre-papermaking layer is also compressed, and the thickness of the resulting papermaking layer 12 is smaller than that of the pre-papermaking layer.

[0075] The above-mentioned manufacturing method is an example, and the manufacturing method of the present invention is not limited to this. Modifications, improvements, etc. within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0076] The present invention will be described in detail based on examples and comparative examples, but the present invention is not limited to these examples.

[0077] <Material> [Fiber reinforced plastic layer] The following prepregs were used as fiber reinforced plastic layers. Prepreg: TORAYCA (registered trademark) carbon fiber "T700SC / 2592" manufactured by Toray Industries, Inc. (thickness 0.14 mm), continuous carbon fibers oriented in one direction

[0078] [Paper forming layer] Paper sheets 1 and 2 shown in Table 1 were produced by the following procedure and used as paper layers in the laminate described below. (raw materials) Reinforced short fibers: Carbon fiber, Toray "T800SC" fiber length 6mm SWP: High-density polyethylene, Mitsui Chemicals "SWP E400" Pulp: Twaron 1094 (registered trademark) manufactured by Teijin Ltd. Resin: Epoxy resin (procedure) The above raw materials were added to water as a dispersion medium in the proportions (mass %) shown in Table 1, and the mixture was 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 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 at a pressure of 3 MPa to dehydrate them to a dehydration rate of 20%. The dehydrated aggregates were then dried at 70°C for 3 hours to obtain a paper sheet. 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%.

[0079] [Table 1]

[0080] <Preparation of carbon fiber reinforced plastic laminate> First, eight prepregs were prepared and stacked with the fiber direction of each prepreg in the same direction to create eight fiber-reinforced plastic layers. Note that for the third to sixth layers from the bottom, a 1 mm gap L was provided where the prepreg was divided in half in a direction perpendicular to the fiber direction (see Figure 5). The gaps L provided in the third to sixth layers faced each other and were aligned in a plan view. Next, a laminate was obtained by sandwiching a paper sheet between the second and third layers and between the sixth and seventh layers so as to cover the gap L. The width direction of the paper sheet was aligned with the fiber direction of the prepreg (i.e., the width direction of the paper sheet was aligned across the direction in which the 1 mm gap L extended). The prepreg and the paper-made sheet were then laminated together by autoclaving under the following conditions: Pressure inside the vessel: 0.2 MPa, Temperature inside the vessel: 90°C, held for 60 minutes, then held at 135°C for 270 minutes. FIG. 5 is a schematic diagram showing the layer structure of the laminate produced in the example, but the dimensional ratio, thickness, number of fibers, etc. differ from the actual ones.

[0081] <Evaluation> Damage resistance (delamination) The resulting laminate was evaluated for damage resistance by the following method. First, a uniaxial tensile test was performed on each laminate (test piece) using a tensile testing machine ("Tensilon RTF-1350" manufactured by A&D) at a crosshead speed of 0.5 mm / min. Strain gauges ("KFGS-5-120-C1-11L1M2R" manufactured by Kyowa Electronics) were attached to the test piece at positions 10 mm apart from the center of the test piece along the long side, using instant adhesive ("CC-33A" manufactured by Kyowa Electronics). From the obtained stress-strain curves, the stress (MPa) at the time of initial delamination and the stress (MPa) at the time of interlaminar delamination were calculated. The results are shown in Table 2.

[0082] Presence or absence of voids The side surfaces of each laminate under test were observed at a magnification of 100 times using an optical microscope ("VHX-2000" manufactured by Keyence Corporation) and evaluated according to the following criteria. The results are shown in Table 2. (standard) A: No voids were observed B: Voids were observed C: Many voids were observed

[0083] [Table 2]

[0084] Photographs taken of the side surfaces of Example 1 and Comparative Example 1 during the test are shown in FIGS. 5 and 6 together with the applied stress. In Figures 5 and 6, the approximately rectangular gray area in the center indicates the resin part, the gray areas extending to the left and right to include the upper and lower sides of the approximately rectangular gray area indicate the papermaking sheet, and the other fibrous (linear) white areas indicate the fiber-reinforced plastic layer. Figures 5 and 6 show that as the stress increases, black cracks appear in the white parts and the cracks gradually grow larger. It was confirmed that the cracks penetrate into the sheet, that is, between the fiber-reinforced plastic layers, causing delamination.

[0085] Furthermore, when the state of the side surface at the center of each test piece was observed, it was confirmed that the end surface was covered with the resin portion in both the example and the comparative example. [Explanation of symbols]

[0086] 10 Continuous Fiber 10a end face 11 Fiber-reinforced plastic layer 12 Papermaking layer 15 Resin 30 Resin part 100 laminate 101 laminate 102 laminate

Claims

1. A laminate in which a fiber-reinforced plastic layer having continuous fibers oriented in one direction and a papermaking layer are laminated, Within the laminate, the fiber-reinforced plastic layer has an end surface where the continuity of the continuous fibers is interrupted, A laminate in which the papermaking layer is provided at a position adjacent to the end surface.

2. The laminate according to claim 1, The end surface is composed of a plurality of adjacent continuous fibers.

3. The laminate according to claim 1 or 2, The thickness (mm) of the papermaking layer is 5 to 35% of the thickness (mm) of the fiber-reinforced plastic layer.

4. The laminate according to claim 1 or 2, The end surface is covered with a resin portion having a relatively larger amount of resin than the fiber-reinforced plastic layer and the papermaking layer.

5. The laminate according to claim 4, The resin portion is located at a step caused by a difference in surface area of ​​the laminated fiber-reinforced plastic layers.

6. The laminate according to claim 4, In a plan view of the laminate, the resin portion is surrounded by the adjacent papermaking layer.

7. The laminate according to claim 4, A laminate, wherein the papermaking layers are provided so as to sandwich the resin portion in a layer direction of the laminate.

8. The laminate according to claim 4, The resin portion includes at least one of a resin constituting the fiber-reinforced plastic layer and a resin constituting the papermaking layer.

9. The laminate according to claim 1 or 2, The fiber-reinforced plastic layer comprises one or two fibers selected from glass fiber and carbon fiber.

10. The laminate according to claim 1 or 2, The laminate has one or more selected from a bent portion, a stepped portion, an inclined portion, and a combination thereof in its plane.

11. The laminate according to claim 1 or 2, The laminate has a functional hole, and the end face is exposed to an inner wall of the functional hole.

12. The laminate according to claim 1 or 2, The laminate, wherein the papermaking layer contains reinforcing short fibers.

13. The laminate of claim 12, The reinforcing short 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.

14. The laminate according to claim 1 or 2, The laminate, wherein the papermaking layer contains at least one of a thermosetting resin and a thermoplastic resin.

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