Composite material, molded body, and method for manufacturing composite material

Abstract

Provided is a composite material comprising a thermoplastic resin and continuous fibers, wherein fibers constituting the continuous fibers include at least a group of fibers along a first fiber direction along one direction, and the surface kurtosis (Rku) in a direction intersecting the first fiber direction on at least one principal surface of a first principal surface or a second principal surface of the composite material is at least 3.0.

Description

Composite material, molded body, and method for manufacturing composite material

[0001] The present invention relates to a composite material, a molded body, and a method for producing a composite material.

[0002] Composite materials containing resin and fiber are called fiber-reinforced plastics (FRP). Composite materials containing thermoplastic resin and continuous fiber include organosheets and UD tapes (unidirectional tapes). These materials are highly versatile due to their high mechanical strength and moldability.

[0003] Composite materials that focus on surface roughness have been proposed (Patent Documents 1 to 5). Patent Documents 1 to 4 describe composite materials with excellent surface smoothness. Patent Document 5 describes a composite material to which a concave-convex shape formed on a roll is transferred.

[0004] Japanese Patent Application Laid-Open No. 2022-150747 International Publication No. 2020 / 196600 International Publication No. 2017 / 203893 Japanese Patent Application Laid-Open No. 05-098042 Japanese Patent Application Laid-Open No. 2000-102978

[0005] However, the inventors have found that even composite materials with controlled surface smoothness may be prone to peeling when stacked together, and therefore there is a demand for composite materials that have excellent peel strength (resistance to peeling) when stacked together.

[0006] An object of the present invention is to provide a composite material that has excellent peel strength when used in layers, a molded article formed from the composite material, and a method for producing the composite material.

[0007] As a result of intensive research to solve the above problems, the present inventors have come up with the following invention and found that the above problems can be solved.

[0008] [1] A composite material comprising a thermoplastic resin and continuous fibers, wherein the fibers constituting the continuous fibers include at least a group of fibers aligned along a first fiber direction along one direction, and the surface kurtosis (Rku) in a direction intersecting the first fiber direction on at least one of the first and second main surfaces of the composite material is 3.0 or greater. [2] The composite material according to [1], wherein the continuous fibers are unidirectional fibers aligned only along the first fiber direction. [3] The composite material according to [1] or [2], wherein the thermoplastic resin comprises a polyamide-based resin. [4] The composite material according to [3], wherein the polyamide comprises a semi-aromatic polyamide-based resin. [5] The composite material according to any one of [1] to [4], wherein the continuous fibers comprise at least one fiber selected from the group consisting of carbon fiber, glass fiber, ceramic fiber, synthetic fiber, natural fiber, and metal fiber. [6] The composite material according to any one of [1] to [5], wherein the continuous fibers comprise carbon fiber. [7] The composite material according to any one of [1] to [6], wherein the fiber volume fraction (Vf) of the composite material is 30% or more and 70% or less. [8] The composite material according to any one of [1] to [7], wherein the thickness of the composite material is 0.10 mm or more and 0.30 mm or less. [9] A molded product formed from the composite material according to any one of [1] to [8].

[10] A method for producing a composite material containing a thermoplastic resin and continuous fibers, comprising: mixing the thermoplastic resin and continuous fibers in a molten state, and discharging the resulting melt at a temperature higher than the glass transition temperature of the thermoplastic resin; and bringing the discharged melt into contact with a cooling body having a smooth surface within 5 seconds to cool the melt to a temperature lower than the glass transition temperature of the thermoplastic resin, thereby obtaining a composite material.

[11] The method for producing a composite material according to

[10] , wherein the melt is cooled using a cooling roll as the cooling body.

[12] The method for producing a composite material according to

[11] , wherein the surface of the melt opposite to the surface of the melt in contact with the cooling roll is brought into contact with a gaseous refrigerant to cool the melt.

[0009] According to the present invention, it is possible to provide a composite material that has excellent peel strength when used in layers; a molded article formed from the composite material; and a method for producing the composite material.

[0010] The following describes an example of an embodiment of the present invention (hereinafter, sometimes referred to as "this embodiment"). However, the embodiment described below is merely an example for embodying the technical concept of the present invention, and the present invention is not limited to the following description. Furthermore, although preferred embodiments are shown in this specification, combinations of two or more of the individual preferred embodiments are also preferred. For matters indicated as numerical ranges, when there are several numerical ranges, the lower and upper limits can be selectively combined to form a preferred embodiment. In this specification, when a numerical range is described as "XX to YY," it means "XX or more and YY or less." Furthermore, in this specification, "units" (where "~" indicates a monomer) mean "structural units derived from ~," for example, "dicarboxylic acid units" mean "structural units derived from dicarboxylic acids," and "diamine units" mean "structural units derived from diamines."

[0011] <Composite Material> The composite material according to this embodiment is a composite material containing a thermoplastic resin and continuous fibers, wherein the fibers constituting the continuous fibers include at least a group of fibers aligned in a first fiber direction along one direction, and at least one of the first and second main surfaces of the composite material has a surface kurtosis (Rku) of 3.0 or more in a direction intersecting the first fiber direction. This makes it possible to provide a composite material with excellent peel strength when used in layers; as well as a molded article formed from the composite material and a method for producing the composite material. Here, in the present invention, the first fiber direction refers to the MD direction.

[0012] Kurtosis is generally a parameter indicating "sharpness." Considering the peaks and tails on the surface of the object to be measured as elements that constitute the sharpness, if the peaks and tails form a normal distribution, the value of surface kurtosis Rku is 3.0. A surface kurtosis Rku greater than 3.0 means that the peaks on the surface are sharply pointed and the tail is long. Kurtosis can be measured using a surface roughness measuring device. Specifically, surface kurtosis Rku is measured in accordance with JIS B 0601:2001 by the method described in the Examples section. In this embodiment, surface kurtosis Rku is measured in a direction perpendicular to the first fiber direction of the continuous fibers of the composite material. Surface kurtosis Rku is measured at multiple locations, and the average of the measured values ​​is calculated and used as the value of surface kurtosis Rku.

[0013] In this embodiment, from the viewpoint of more significantly achieving the effects of the present invention, the surface kurtosis Rku is preferably greater than 3.0, more preferably 3.1 or greater, even more preferably 3.3 or greater, still more preferably 3.5 or greater, particularly preferably 3.8 or greater, and most particularly preferably 4.0 or greater. In this embodiment, the upper limit of the surface kurtosis Rku is not limited as long as the composite material is produced by the method described below, but may be, for example, 6.5 or less or 5.5 or less. The surface kurtosis Rku can be adjusted, for example, according to the method for producing a composite material described below.

[0014] The composite material according to this embodiment has a shape having a first main surface and a second main surface, for example, a sheet or tape shape. The surface to be measured for surface kurtosis Rku may be at least one of the first and second main surfaces of the composite material according to this embodiment. In other words, a composite material having one or two main surfaces with a surface kurtosis Rku value of 3.0 or more constitutes the composite material according to this embodiment. The composite material according to this embodiment preferably has a surface kurtosis (Rku) of 3.0 or more on both the first and second main surfaces, thereby achieving the effects of the present invention on both sides.

[0015] Each component of the composite material of this embodiment will be described below.

[0016] [Thermoplastic Resin] The thermoplastic resin used in this embodiment is not limited as long as it can constitute the matrix resin of the composite material, and may be a crystalline resin, an amorphous resin, or may contain both a crystalline resin and an amorphous resin.

[0017] Examples of thermoplastic resins include polyolefin resins such as polyethylene resin, polypropylene resin, and copolymers and blends thereof; polyamide resins; aromatic polyester resins such as polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate (PTT) resin, and polyethylene naphthalate (PEN) resin; aliphatic polyester resins such as polycarbonate resin, polystyrene resin (polystyrene resin, AS resin, ABS resin, etc.), and polylactic acid resin; polyacetal (POM), polyphenylene sulfide (PPS), and polyketone (PK) resin. , polyether ketone (PEK) resin, polyether ether ketone (PEEK), polyaryl ether ketone (PAEK), polyether ketone ketone (PEKK), polyarylate (PAR) resin, polyether nitrile (PEN) resin, polysulfone, polyether sulfone, polythioether sulfone, polyarylate, polyimide, polyamide imide (PAI), polymethyl methacrylate, polyether sulfone (PES), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyacrylonitrile, polyurethane, polyvinyl chloride, liquid crystal polyester, etc. These may be used alone or in combination.

[0018] From the viewpoint of excellent mechanical strength and heat resistance, the thermoplastic resin preferably contains a polyamide-based resin. More preferably, the thermoplastic resin contains at least one selected from an aliphatic polyamide-based resin, an alicyclic polyamide-based resin, and a semi-aromatic polyamide-based resin. From the viewpoint of even more excellent mechanical strength and heat resistance, the thermoplastic resin more preferably contains at least one selected from semi-aromatic polyamide-based resins, and particularly preferably contains a semi-aromatic polyamide resin containing diamine units mainly composed of aliphatic diamine units and dicarboxylic acid units mainly composed of aromatic dicarboxylic acid units.

[0019] Here, "aliphatic polyamide resin" refers to a resin composed of diamine units, primarily composed of aliphatic diamine units, and aliphatic dicarboxylic acid units. "Alicyclic polyamide resin" refers to a resin composed of a compound in which at least one of the dicarboxylic acid and diamine monomers constituting the polyamide has an alicyclic chemical structure. "Semi-aromatic polyamide resin" refers to a polyamide containing diamine units, primarily composed of aliphatic diamine units, and dicarboxylic acid units, primarily composed of aromatic dicarboxylic acid units, or a polyamide containing dicarboxylic acid units, primarily composed of aliphatic dicarboxylic acid units, and diamine units, primarily composed of aromatic diamine units. "Mainly composed" here refers to a composition comprising 50 to 100 mol %, preferably 60 to 100 mol %, of all units.

[0020] Examples of the dicarboxylic acid unit include structural units derived from aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, dimethylmalonic acid, 3,3-diethylsuccinic acid, 2,2-dimethylglutaric acid, 2-methyladipic acid, and trimethyladipic acid; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, and cyclodecanedicarboxylic acid; and aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid, 4,4'-biphenyldicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, and diphenylsulfone-4,4'-dicarboxylic acid. These units may be of one type or of two or more types.

[0021] From the viewpoints of mechanical strength, heat resistance, and chemical resistance, the dicarboxylic acid units preferably contain aromatic dicarboxylic acid units, more preferably 40 to 100 mol % of the dicarboxylic acid units being aromatic dicarboxylic acid units, still more preferably 60 to 100 mol % of the dicarboxylic acid units being aromatic dicarboxylic acid units, and particularly preferably 80 to 100 mol % of the dicarboxylic acid units being aromatic dicarboxylic acid units.

[0022] In addition, from the viewpoints of mechanical strength, heat resistance, and chemical resistance, the aromatic dicarboxylic acid unit preferably contains a terephthalic acid unit. The polyamide resin may also contain a structural unit derived from a trivalent or higher polycarboxylic acid such as trimellitic acid, trimesic acid, or pyromellitic acid, to the extent that melt molding is possible.

[0023] Examples of the diamine unit include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 1,3-dimethyl- 1,4-butanediamine, 1,4-dimethyl-1,4-butanediamine, 2,3-dimethyl-1,4-butanediamine, 2-ethyl-1,4-butanediamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2-propyl-1,6-hexanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 3,3-dimethyl-1,6-hexanediamine, 2,2-dimethyl-1,6-hexanediamine, 2-ethyl-1,6-hexanediamine, 2 , 2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-propyl-1,6-hexanediamine, 2,4-diethyl-1,6-hexanediamine, 2-ethyl-1,7-heptanediamine, 2,2-dimethyl-1,7-heptanediamine, 2,3-dimethyl-1,7-heptanediamine, 2,4-dimethyl-1,7-heptanediamine, 2,5-dimethyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine, 4- aliphatic diamines such as methyl-1,8-octanediamine, 1,3-dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8-octanediamine, 4,5-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 3,3-dimethyl-1,8-octanediamine, 4,4-dimethyl-1,8-octanediamine, 2-ethyl-1,8-octanediamine, and 5-methyl-1,9-nonanediamine;Examples of structural units include those derived from alicyclic diamines such as cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, norbornanedimethylamine, and tricyclodecanedimethyldiamine; and aromatic diamines such as p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, and 4,4'-diaminodiphenylether. These units may be of one type or two or more types.

[0024] From the viewpoint of strength under high temperature and high humidity conditions, the diamine units preferably contain aliphatic diamine units having 6 to 12 carbon atoms, preferably 60 to 100 mol % of the diamine units are aliphatic diamine units having 6 to 12 carbon atoms, more preferably 70 to 100 mol % of the diamine units are aliphatic diamine units having 6 to 12 carbon atoms, and even more preferably 90 to 100 mol % of the diamine units are aliphatic diamine units having 6 to 12 carbon atoms.

[0025] Furthermore, among the aliphatic diamines having 6 to 12 carbon atoms, from the viewpoint of strength under high temperature and high humidity conditions, it is preferable to contain a structural unit derived from at least one selected from the group consisting of 1,6-hexanediamine, 2-methyl-1,5-pentanediamine, 1,8-octanediamine, 2-methyl-1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine, and the structural unit is preferably selected from the group consisting of 2-methyl-1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine. It is more preferable that the copolymer contains a structural unit derived from at least one type, and even more preferable that the copolymer contains a structural unit derived from at least one type selected from the group consisting of 2-methyl-1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, and 1,11-undecanediamine. It is even more preferable that the copolymer contains a structural unit derived from at least one type selected from the group consisting of 2-methyl-1,8-octanediamine, 1,9-nonanediamine, and 1,10-decanediamine, and it is particularly preferable that the copolymer contains a structural unit derived from at least one type selected from the group consisting of 1,9-nonanediamine and 2-methyl-1,8-octanediamine.

[0026] When the diamine units contain both structural units derived from 1,9-nonanediamine and structural units derived from 2-methyl-1,8-octanediamine, from the viewpoint of strength under high temperature and high humidity conditions, the molar ratio of structural units derived from 1,9-nonanediamine to structural units derived from 2-methyl-1,8-octanediamine (structural units derived from 1,9-nonanediamine / structural units derived from 2-methyl-1,8-octanediamine) is preferably in the range of 95 / 5 to 40 / 60, more preferably 90 / 10 to 45 / 55, and even more preferably 90 / 10 to 50 / 50. Depending on the application, a range of structural units derived from 1,9-nonanediamine / structural units derived from 2-methyl-1,8-octanediamine of 55 / 45 to 45 / 55 may also be preferable.

[0027] The polyamide resin may contain an aminocarboxylic acid unit. Examples of the aminocarboxylic acid unit include units derived from lactams such as caprolactam and lauryllactam; and aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. The content of the aminocarboxylic acid unit in the polyamide resin is preferably 40 mol% or less, and more preferably 20 mol% or less, relative to 100 mol% of the total of the dicarboxylic acid units and diamine units in the polyamide resin.

[0028] The polyamide resin may contain units derived from a terminal blocking agent. Examples of the terminal blocking agent include monofunctional compounds reactive with terminal amino groups or terminal carboxyl groups. Specific examples of the terminal blocking agent include monocarboxylic acids (e.g., acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid), acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, and monoamines (e.g., butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline).

[0029] The polyamide resin is preferably PA6T, PA9T, PA10T, PA12T, PA10T / 10I, PA10T / 10, PA10T / 12, or PA10T / 11.

[0030] (Glass transition temperature Tg) From the viewpoint of strength at high temperatures, the glass transition temperature Tg of the thermoplastic resin is preferably 100° C. or higher, more preferably 110° C. or higher, and even more preferably 120° C. or higher. From the viewpoint of processability, it is preferably 280° C. or lower, more preferably 240° C. or lower. The glass transition temperature Tg can be measured using a differential scanning calorimetry (DSC) device by the method described in the examples.

[0031] (Melting point Tm) From the viewpoint of strength at high temperatures, the melting point of the thermoplastic resin is preferably 200° C. or higher, more preferably 230° C. or higher, and even more preferably 250° C. or higher. From the viewpoint of processability, the melting point is preferably 350° C. or lower, and more preferably 320° C. or lower. The melting point Tm can be measured using a differential scanning calorimetry (DSC) analyzer by the method described in the examples.

[0032] (Inherent Viscosity) From the viewpoint of excellent mechanical strength or excellent moldability, the inherent viscosity of the thermoplastic resin is preferably 0.5 dL / g to 2.0 dL / g, more preferably 0.7 dL / g to 1.5 dL / g. The inherent viscosity can be measured by measuring the flow time of a solution using concentrated sulfuric acid as a solvent at a concentration of 0.2 g / dL and a temperature of 30°C.

[0033] (Specific gravity) The specific gravity can be measured in accordance with ISO 1183-1 (2019) Method A (underwater displacement method) using an electronic hydrometer (model ED-120T) manufactured by Alpha Mirage.

[0034] (Thermoplastic Resin Content) From the viewpoint of mechanical strength, the content of the thermoplastic resin is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass, of all components excluding the continuous fibers of the composite material according to this embodiment.

[0035] (Method for producing thermoplastic resin) As the thermoplastic resin, commercially available products may be used, or resins obtained by modifying commercially available products may be used. A produced thermoplastic resin may also be used. As an example, the polyamide-based resin can be produced using a known method. For example, it can be produced by a solution polymerization method or an interfacial polymerization method using acid chloride and diamine as raw materials, a melt polymerization method using dicarboxylic acid and diamine as raw materials, a solid-state polymerization method, a melt extrusion polymerization method, or the like.

[0036] [Continuous fiber] Continuous fiber refers to a long fiber that can be reeled out. The fibers constituting the continuous fiber used in the composite material according to this embodiment include at least a group of fibers aligned along a first fiber direction that is along one direction. One example of such a continuous fiber is a unidirectional fiber aligned only along the first fiber direction. Another example of such a continuous fiber is a woven or knitted fabric that includes at least a group of fibers aligned along the first fiber direction and a group of fibers aligned along a second direction different from the first fiber direction.

[0037] The continuous fiber is not limited as long as it has a higher flow initiation temperature than the thermoplastic resin, and any type of continuous fiber can be used. Examples of continuous fibers include inorganic fibers such as carbon fiber, glass fiber, silicon carbide fiber, alumina fiber, boron fiber, ceramic fiber, basalt fiber, and metal (e.g., gold, silver, copper, iron, nickel, titanium, stainless steel, etc.) fibers; synthetic fibers such as organic fibers such as wholly aromatic polyester fiber, polyphenylene sulfide fiber, polyparaphenylene benzobisoxazole fiber, aramid fiber, polyoxymethylene fiber, polyethylene fiber, polysulfonamide fiber, phenolic resin fiber, polyimide fiber, and fluorine fiber; and natural fibers such as plant fibers such as kenaf and bamboo fiber. The continuous fiber may be surface-treated with at least one surface modifier such as a coupling agent and a sizing agent. An example of a woven fabric is non-crimp fabric (NCF). As the continuous fiber, one of these may be used alone, or two or more may be used in combination. Among these, from the viewpoint of mechanical strength, it is preferable to include at least one fiber selected from the group consisting of carbon fiber, glass fiber, ceramic fiber, synthetic fiber, natural fiber, and metal fiber, and it is more preferable to include carbon fiber.

[0038] (Strength) From the viewpoint of the strength of the composite material, the tensile strength of the continuous fibers is preferably 2000 to 8000 MPa, and more preferably 3000 to 6000 MPa.

[0039] (Fiber diameter, number of filaments) The number average fiber diameter of the continuous fibers is preferably 1 to 100 μm, more preferably 3 to 50 μm, and even more preferably 5 to 15 μm. Continuous fibers having, for example, about 100 to 100,000 filaments can be used depending on the purpose. The number average fiber diameter and number of filaments of the continuous fibers can be observed, for example, using a scanning electron microscope.

[0040] (Fiber Volume Content (Vf)) From the viewpoint of mechanical strength, the fiber volume content (Vf) of the continuous fibers in the composite material according to this embodiment is preferably 30% or more, more preferably 40% or more, and even more preferably 45% or more, and from the viewpoint of shape freedom, it is preferably 70% or less, more preferably 65% ​​or less, and even more preferably 60% or less. The fiber volume content (Vf) is the ratio (percentage) of the volume of the continuous fibers in the composite material to the total volume of the composite material. The volume of the continuous fibers in the composite material can be calculated from the weight and specific gravity of the continuous fibers used in producing the composite material by the method described in the Examples.

[0041] The total amount of the continuous fibers and the thermoplastic resin in the composite material according to this embodiment is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass.

[0042] The continuous fibers may be commercially available products as they are, or may be surface-treated. The continuous fibers may also be recycled or reused products. Recycled or reused products are obtained, for example, by removing the matrix resin from a composite material.

[0043] [Other Components] The composite material according to this embodiment may contain a heat stabilizer, a light stabilizer, an elastomer, a lubricant, a nucleating agent, a crystallization retarder, a hydrolysis inhibitor, an antistatic agent, a radical inhibitor, a matting agent, an ultraviolet absorber, a flame retardant, an inorganic substance other than the continuous fiber, and the like, as long as the effects of the present invention are not impaired.

[0044] Examples of the heat stabilizer include phenol-based heat stabilizers, phosphorus-based heat stabilizers, sulfur-based heat stabilizers, amine-based heat stabilizers, copper-based heat stabilizers, and derivatives thereof.

[0045] Examples of the phenol-based heat stabilizer include 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide], triethylene glycol bis(3-t-butyl-4-hydroxy-5-methylphenyl)propionate, hexamethylene bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide), diphenyl)propionate), 3,9-bis[1,1-dimethyl-2-[β{(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and the like.

[0046] Examples of the phosphorus-based heat stabilizer include monosodium phosphate, disodium phosphate, trisodium phosphate, sodium phosphite, calcium phosphite, magnesium phosphite, manganese phosphite, triphenyl phosphite, trioctadecyl phosphite, tridecyl phosphite, trinonylphenyl phosphite, diphenylisodecyl phosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphonite, and tetrakis(2,4-di-t-butyl-5-methyl phenyl)-4,4'-biphenylene diphosphonite), bis(2,4-dicumylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, tris(2,4-di-t-butylphenyl)phosphite, 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]-dioxaphosphepine, and the like.

[0047] Examples of the sulfur-based heat stabilizer include distearyl 3,3′-thiodipropionate, pentaerythrityl tetrakis(3-laurylthiopropionate), 2-mercaptobenzimidazole, didodecyl 3,3′-thiodipropionate, ditridecyl 3,4′-thiodipropionate, and 2,2-bis[[3-(dodecylthio)-1-oxopropoxy]methyl]-1,3-propanediyl ester.

[0048] Examples of the amine-based heat stabilizer include 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N,N'-di-2-naphthyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-1-naphthylamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, and N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine.

[0049] Examples of the copper-based heat stabilizer include copper halides such as copper iodide and derivatives thereof.

[0050] Examples of lubricants include metal soaps, Montan acid wax, polyolefin wax, fatty acid amide wax, and rice wax. Examples of crystallization retarders include azine dyes such as nigrosine and its derivatives. Examples of chain extenders include compounds having functional groups that react with the amino or carboxyl groups at the polyamide terminals, such as 1,3-phenylenebisoxazoline, oxazolines, imidazolines, epoxy, isocyanates, maleimides, and acid anhydrides. These other additives may be contained alone or in combination of two or more.

[0051] Examples of inorganic substances include carbon nanotubes, fullerenes, talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, silica, bentonite, alumina silicate, silicon oxide, magnesium oxide, alumina, zirconium oxide, titanium oxide, iron oxide, calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, barium sulfate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, glass beads, glass flakes, glass powder, ceramic beads, boron nitride, silicon carbide, carbon black, and graphite.

[0052] The amount of the other additives is not particularly limited as long as it does not impair the effects of the present invention, but is, for example, 0.01 to 100 parts by mass per 100 parts by mass of the thermoplastic resin.

[0053] [Characteristics of Composite Material] (Average Thickness of Composite Material) From the viewpoint of mechanical strength, the average thickness of the composite material of the present invention is preferably 0.10 mm or more, more preferably 0.13 mm or more. From the viewpoint of formability, it is preferably 0.30 mm or less, more preferably 0.25 mm or less, even more preferably 0.22 mm or less, and may be 0.18 mm or less. The average thickness of the composite material can be measured by the method described in the Examples section.

[0054] (Peel strength when used in layers) When the composite material of this embodiment is layered to form a laminate, it exhibits a high peel strength between the composite materials. This peel strength can be evaluated by the maximum peel strength. The maximum peel strength can be measured by the method described in the Examples section below. The maximum peel strength of the composite material measured in this manner is preferably 25 N / 10 mm or more, more preferably 26 N / 10 mm or more, even more preferably 27 N / 10 mm or more, and in some cases may be 30 N / 10 mm or more.

[0055] <Method for producing a composite material> A composite material can generally be produced by mixing, preferably impregnating, a molten thermoplastic resin with continuous fibers, and solidifying the resulting melt. In the molten composite material, the thermoplastic resin is in a molten state, and the continuous fibers are usually not in a molten state. Such a production method is similar to a known method for producing a so-called UD sheet or UD tape (for example, the method described in Japanese Patent No. 6,890,547).

[0056] In order to produce the composite material of this embodiment (i.e., a composite material having a surface kurtosis Rku of 3.0 or more), it is preferable to adopt at least one of the following manufacturing methods: the first manufacturing method for a composite material (hereinafter also referred to as the "first manufacturing method") and the second manufacturing method for a composite material (hereinafter also referred to as the "second manufacturing method") described below.

[0057] [First Production Method] The first production method according to this embodiment is a method for producing a composite material containing a thermoplastic resin and continuous fibers, and includes mixing the thermoplastic resin in a molten state with the continuous fibers, and discharging the resulting molten material at a temperature higher than the glass transition temperature of the thermoplastic resin, and bringing the discharged molten material into contact with a cooling body with a smooth surface within 5 seconds to cool the molten material to a temperature lower than the glass transition temperature of the thermoplastic resin, thereby obtaining a composite material.

[0058] (Cooling Start Timing) In the first manufacturing method, the timing at which the melt starts to come into contact with the cooling body is when the melt is at a temperature higher than the glass transition temperature and has not yet started to solidify.

[0059] The timing at which the melt begins to solidify depends on the temperature of the impregnation head, the glass transition temperature of the thermoplastic resin, and the like. Typically, solidification begins 5 seconds after the melt is discharged from the impregnation head. Therefore, in this first manufacturing method, the cooling start timing is set to within 5 seconds. A shorter time may be set as the cooling start timing, but in that case, a smooth-surfaced cooling body must be provided in close proximity to the impregnation head or the line speed must be increased. Setting the cooling start timing in this manner ensures that the melt can be cooled before it begins to solidify.

[0060] Then, by cooling the melt using a cooling body with a smooth surface before solidification of the melt has begun, i.e., by cooling at a rate faster than natural cooling, the surface kurtosis Rku value of the composite material can be increased. From the viewpoint of achieving high-speed cooling, the surface temperature of the cooling body is preferably 90°C or less, more preferably 70°C or less, and even more preferably 50°C or less. A level of smoothness that would be naturally understood by a person skilled in the art is sufficient for the surface smoothness of the cooling body, but for example, the surface roughness Ra is 1 μm or less, preferably 0.5 μm or less, and more preferably 0.1 μm or less. The surface roughness Ra can be measured using a surface roughness meter.

[0061] The reason why the value of surface kurtosis Rku can be increased is not clear, but it is thought that when a cooling body with a smooth surface comes into contact with the melt, the continuous fibers near the surface of the melt are realigned and placed in an appropriate position within the matrix resin, and the matrix resin solidifies in this state, thereby ensuring a wide base that is evaluated by surface kurtosis Rku, and in comparison, the peaks on the surface of the solidified matrix resin become more prominent, resulting in a larger value of surface kurtosis Rku.

[0062] In the first production method, it is preferable to use a cooling roll as the cooling body to cool the melt. By using a cooling roll, the cooling surface can be continuously brought into contact with the melt. The cooling roll may be used on one or both sides of the melt. A more preferred first production method is a production method in which one side of the melt is brought into contact with the cooling roll and a gaseous refrigerant is brought into contact with the side of the melt opposite the contacted side to cool the melt.

[0063] Examples of the gaseous refrigerant include air and inert gases, preferably at a temperature of 40° C. or less, more preferably 30° C. or less, and even more preferably 20° C. or less. From the viewpoint of preventing moisture from entering the melt, the gaseous refrigerant is preferably a dehumidified refrigerant. From the viewpoint of improving cooling efficiency, the contact area between the refrigerant and the melt is preferably larger than the contact area between the cooling roll and the melt.

[0064] In the first production method, the composite material may be brought into contact with a cooling medium, such as the cooling roll or the gaseous refrigerant, if necessary, to remove the residual heat from the composite material.

[0065] While the first manufacturing method described above is a method for directly manufacturing the composite material according to this embodiment, the second manufacturing method describes a method for manufacturing the composite material according to this embodiment from an existing composite material. This second manufacturing method includes a surface modification method in which the surface of the existing composite material is modified to increase the surface kurtosis (Rku) in a direction intersecting the first fiber direction.

[0066] Specifically, the second manufacturing method according to this embodiment is a manufacturing method for a composite material, which includes a step of bringing a composite material containing a thermoplastic resin and continuous fibers into contact with a smooth-surfaced heated body while conveying the composite material in a direction along the first fiber direction of the continuous fibers. The smooth-surfaced heated body is preferably a heated roll, and more preferably a pair of heated rolls. Furthermore, at least one of the pair of heated rolls is preferably a pressing roll, and more preferably one is a pressing roll and the other is a fixed roll. In the second manufacturing method according to this embodiment, it is preferable to nip the composite material with the pair of heated rolls. The nip pressure is not particularly limited, but it is preferable to apply pressure uniformly to the composite material.

[0067] The surface temperature of the heating body is not limited as long as it can melt at least a part of the thermoplastic resin, but is preferably 50° C. or higher, more preferably 80° C. or higher, and even more preferably 120° C. or higher, and the upper limit may be, for example, 350° C. or lower or 340° C. The smoothness of the surface of the heating body is equivalent to the smoothness of the surface of the cooling body described above.

[0068] In the second production method, the speed at which the composite material is conveyed is not particularly limited, but from the viewpoint of more significantly exhibiting the effects of the present invention, it is preferably in the range of 0.10 to 2.0 m / min, and more preferably in the range of 0.15 to 1.5 m / min.

[0069] According to the second manufacturing method, the composite material is softened at least partially by contact with a heater, causing the continuous fibers to realign. This increases the surface kurtosis (Rku) in a direction intersecting the first fiber direction. The manufacturing method for the composite material according to this embodiment may employ the first manufacturing method and then the second manufacturing method, and preferably employs the first manufacturing method and then the second manufacturing method.

[0070] <Molded Article> The composite material of this embodiment can be further shaped into an industrially useful shape using a known method. For example, press molding is performed by stacking multiple composite materials to form a laminate, sandwiching them between molds, and applying heat and pressure; overmolding is performed by injection molding other materials simultaneously with the press molding; tape winding and sheet winding are performed by wrapping the composite around a cylindrical mold and then applying heat and pressure; and auto tape layup and auto fiber placement are performed using an automatic lamination device that automatically laminates multiple layers of composite materials. In this way, a molded article according to this embodiment can be obtained.

[0071] The molded article according to this embodiment is formed from the composite material according to this embodiment described above. Here, as described above, the composite material according to this embodiment has excellent peel strength when used in layers. Therefore, the molded article according to this embodiment is preferably a laminate obtained by stacking two or more layers of the composite material. Such a laminate may be subjected to a heat treatment, a pressure treatment, or a heat treatment and a pressure treatment. One example of such a laminate is a laminate in which multiple composite materials are stacked so that the first fiber directions of the composite materials intersect. Another example is a laminate in which multiple composite materials are stacked so that the first fiber directions of the composite materials are parallel.

[0072] (Uses of Composite Material and Molded Article) The composite material of this embodiment can be used, in particular, as a UD tape or an organosheet. Furthermore, the composite material and molded article of this embodiment can be effectively used in a wide range of fields, including general industrial materials, electrical and electronics, civil engineering and construction, transportation equipment, and leisure. In particular, they can be effectively used as main structural components in transportation equipment fields such as aircraft, urban air mobility (UAM), drones, automobiles, railways, and ships. For example, housings for personal computers, displays, office automation equipment, mobile phones, personal digital assistants, digital video cameras, optical equipment, audio equipment, air conditioners, lighting equipment, toys, and other home appliances; electrical and electronic equipment parts such as trays, chassis, and battery cases; civil engineering and architectural parts (buildings, roads, bridges, waterways, embankments, etc.) such as supports, panels, and reinforcing materials; industrial parts such as wind turbine blades; outer panel or body parts such as various members, various frames, various hinges, various arms, various axles, various wheel bearings, various beams, various pillars, various supports, and various rails; exterior parts such as bumpers, moldings, undercovers, engine covers, air rectifiers, spoilers, cowl louvers, and aero parts; interior parts such as instrument panels, seat or tape frames, door trims, pillar trims, handles, and various modules; They are suitable for use in automobile or motorcycle parts such as front bodies, underbodies, various pillars, various members, various frames, various beams, various supports, various rails, various hinges, battery trays for electric vehicles, motor parts, CNG tanks, gasoline tanks, fuel pumps, air intakes, intake manifolds, carburetor main bodies, carburetor spacers, various pipes, and various valves; aircraft parts such as landing gear pods, winglets, spoilers, edges, rudders, elevators, failings, and ribs; and leisure parts such as inner soles and outsoles of sports shoes, racket frames and grommets, golf club heads and sleeves, fishing reels and rods, boat propellers, bicycle suspensions, gears, saddles, and bottle cages.

[0073] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0074] Composite materials according to the examples and comparative examples were prepared as follows and evaluated according to the evaluation methods described below.

[0075] Production Example 1 4861 g of 1,9-nonanediamine, 4861 g of 2-methyl-1,8-octanediamine, 10051 g of terephthalic acid (1,9-nonanediamine:2-methyl-1,8-octanediamine:terephthalic acid=30.7:30.7:60.5 (molar ratio)), 225 g of benzoic acid, 20 g of sodium phosphite, and 5000 g of water were placed in an autoclave and purged with nitrogen. The internal temperature was raised to 200°C over 2 hours. At this time, the autoclave was pressurized to 2 MPa. Thereafter, the reaction was carried out for 2 hours while gradually releasing water vapor to maintain the pressure at 2 MPa. Next, the pressure was reduced to 1.2 MPa over 30 minutes, and a prepolymer was obtained. This prepolymer was pulverized and dried at 120°C under reduced pressure for 12 hours. This was subjected to solid-state polymerization at 230°C and 13.3 Pa for 10 hours to obtain PA9T.

[0076] Next, the PA9T obtained in the production example was evaluated as follows.

[0077] [Measurement of Melting Point and Glass Transition Temperature] The melting point of PA9T obtained in Production Example 1 was determined by using a differential scanning calorimeter (DSC7020) manufactured by Hitachi High-Tech Science Corporation. The melting point (°C) was determined by measuring the peak temperature of the endothermic peak that appeared when the temperature was raised from 30°C to 360°C at a rate of 10°C / min under a nitrogen atmosphere. When there were multiple endothermic peaks, the peak temperature of the endothermic peak on the highest temperature side was taken as the melting point. The sample was then held at a temperature 30°C higher than the melting point for 10 minutes to completely melt it, then cooled to 40°C at a rate of 10°C / min and held at 40°C for 10 minutes. The midpoint at which the DSC curve changed stepwise when the temperature was again raised to a temperature 30°C higher than the melting point at a rate of 10°C / min was taken as the glass transition temperature.

[0078] Example 1 Three bundles of carbon fiber bundles ("T700S C 12K 50C" manufactured by Toray Industries, Inc., number of filaments: 12,000, number average fiber diameter: 7 μm, tensile strength: 4,900 MPa, specific gravity: 1.80) as continuous fibers were unwound from a plurality of unwinders (bobbins), and were passed through a fiber-spreading area to be aligned in one direction, and then supplied while being pulled out so as to pass through the inside of an impregnation head (crosshead die).

[0079] On the other hand, PA9T (1,9-nonanediamine:2-methyl-1,8-octanediamine:terephthalic acid=25:25:50 (molar ratio), crystalline resin, inherent viscosity: 0.90 dl / g, melting point: 264°C, glass transition temperature: 125°C, specific gravity: 1.14) obtained in Production Example 1 was supplied to an extruder connected to the impregnation head and equipped with a feed section, a compression section, and a metering section, and a melt of PA9T was supplied to the impregnation head set at a temperature of 340°C with the feed section set at 310°C, the compression section set at 340°C, and the metering section set at 340°C.

[0080] The PA9T melt supplied by the extruder was impregnated into the continuous fibers in the impregnation head to form a composite melt. The resulting composite melt was discharged from the gate of the impregnation head at a line speed of 1 m / min (=16.7 mm / sec). The impregnation head was installed so that the gate was oriented horizontally. The gate opening size was set to 25 mm in width and approximately 0.15 mm in height. The composite melt immediately after discharge was confirmed to be at a temperature higher than the glass transition temperature of PA9T, specifically 300°C. The PA9T melt that did not contribute to the formation of the composite was recovered without coming into contact with the first cooling roll described below.

[0081] (First Cooling Treatment) 0.9 seconds after the start of discharge from the gate, one side of the molten composite material discharged from the gate was brought into contact with a first cooling roll as a cooling body with a smooth surface, and the other side of the molten composite material was cooled by contacting it with dehumidified air at 20°C as a gaseous refrigerant.

[0082] The first chill roll was installed vertically below the conveyance line for the composite melt, with its contact surface located 15 mm from the gate of the impregnation head. The surface temperature of the first chill roll was set at 30°C.

[0083] The nozzle for supplying the gaseous coolant was located 5 mm away from the conveying line for the composite melt. The nozzle opening had a horizontal dimension of 25 mm in the direction horizontal and perpendicular to the conveying direction of the composite melt, and a vertical dimension of 2 mm in the direction parallel to the horizontal dimension. The discharge speed of the gaseous coolant from the nozzle was set to 9 m / s.

[0084] It was confirmed that this cooling treatment cooled the molten composite material to a temperature lower than the solidification temperature of the thermoplastic resin, and solidified it.

[0085] (Second Cooling Treatment) Subsequently, the composite material obtained by solidification was cooled using a second cooling roll. The second cooling roll was installed on the conveying line at a position downstream of the first cooling roll, specifically, 190 mm from the gate of the impregnation head, and vertically below the conveying line, so that the contact surface was formed. The position 190 mm from the gate of the impregnation head was reached 11.4 seconds after the start of conveyance from the gate. This second cooling treatment removed the rough heat from the composite material.

[0086] The composite material was wound into a roll using a take-up machine and a winding machine provided downstream in the conveying direction. The produced composite material (composite material before heat treatment) had a width of 25 mm, a thickness of 0.15 mm, and a fiber volume fraction (Vf) of 50%.

[0087] (Heat Treatment) The composite material wound into a roll was nipped while being conveyed toward a heating roll at a speed of 1 m / min, thereby producing the composite material of Example 1. A heatable fixed roll and a heatable pressing roll were used as the heating rolls. The fixed roll was installed vertically below the conveying line, and the pressing roll was installed vertically above the conveying line. The surface temperature of each roll was set to 150°C. The composite material of Example 1 had a width of 25 mm, a thickness of 0.15 mm, and a fiber volume content (Vf) of 50%.

[0088] Example 2 A composite material was produced in the same manner as in Example 1, except that the heat treatment was omitted.

[0089] Example 3 A composite material was produced in the same manner as in Example 1, except that the height of the gate opening of the impregnation head was changed to about 0.20 mm and the conveying speed during the heat treatment was changed to 0.2 m / min.

[0090] Example 4 A composite material was produced in the same manner as in Example 3, except that the heat treatment was omitted.

[0091] [Example 5] A composite material was produced in the same manner as in Example 1, except that the number of carbon fiber bundles used as continuous fibers was changed to five, the width and height of the gate opening of the impregnation head were changed to 20 mm and approximately 0.20 mm, respectively, and the conveying speed in the heat treatment was changed to 0.2 m / min.

[0092] Comparative Example 1 A composite material was produced in the same manner as in Example 1, except that the first cooling treatment and the heating treatment were omitted.

[0093] Comparative Example 2 A composite material was produced in the same manner as in Example 5, except that the first cooling treatment and the heating treatment were omitted.

[0094] <Evaluation Method> Subsequently, the composite materials obtained in the examples and comparative examples were evaluated as follows.

[0095] [1. Measurement of Average Thickness of Composite Material] The thickness of each of the composite materials obtained in the Examples and Comparative Examples was measured at three randomly selected points using a micrometer ("Thickness Meter TG-02U" manufactured by Custom Co., Ltd.) to determine the average thickness.

[0096] [2. Measurement of fiber volume fraction (Vf)] The fiber volume fraction Vf of the composite materials obtained in the Examples and Comparative Examples was calculated by measuring the mass W0 of the composite material, then heating the composite material in air at 500°C for 4 hours to burn off the thermoplastic resin component, measuring the mass W1 of the remaining continuous fibers, and using formula (1): Vf (volume %) = (W1 / ρf) / {W1 / ρf + (W0 - W1) / ρr} × 100 (1), where ρf is the density of the continuous fibers (g / cm ３ ) ρr: density of thermoplastic resin (g / cm ３ )

[0097] [3. Measurement of Surface Kurtosis (Rku)] The surface kurtosis (Rku) of each composite material obtained in the Examples and Comparative Examples was measured in accordance with JIS B 0601:2001. A stylus surface roughness meter ("Surfcorder SE700" manufactured by Kosaka Laboratory) was used as the measuring device. The main surface of the composite material to be measured was the surface that came into contact with the second cooling roll. Measurement was performed in a direction perpendicular to the first fiber direction. The measurement magnification was 1000x, the measurement speed was 0.2 mm / s, the cutoff value was 0.25 mm, and the evaluation length was 1.250 mm. Three arbitrary locations in the measurement area were measured, and the average value of the results was adopted as the surface kurtosis Rku. The measurement area was within 5 mm from the center of the tape.

[0098] [4. Evaluation of Peel Force: Measurement of Peel Strength] (4-1. Preparation of Test Pieces) Test pieces for peel adhesion strength tests were prepared using each of the composite materials obtained in the Examples and Comparative Examples as follows.

[0099] First, two rectangular pieces with short sides of 10 mm and long sides of 150 mm were cut out from the composite material. The direction of the long sides of the rectangular pieces coincided with the fiber direction in the composite material.

[0100] Next, one imide film (UPIPEX manufactured by UBE, thickness: 50 μm) was inserted between the two overlapping rectangular pieces up to a position 100 mm from one end of the long side of the rectangular pieces to prepare Material A. In Material A, the two rectangular pieces were in contact with each other in the area not reached by the polyimide film (contact surface). At the contact surface, the surfaces of the two rectangular pieces where the surface kurtosis Rku was measured faced each other.

[0101] Next, a 250 mm square first stainless steel plate (thickness: 3.0 mm), a 240 mm square silicone rubber (thickness: 1.3 mm), an imide film, Material A, an imide film, and a 250 mm square second stainless steel plate (thickness: 3.0 mm) were placed in this order to obtain a laminate. In this laminate, the contact surface of Material A was positioned approximately in the center of the stainless steel plates. Therefore, a portion of Material A was exposed outside the side surfaces of the two stainless steel plates.

[0102] The laminate was then pressed using a press with a cylinder diameter of 113 mm (Kando Metal Industries "AYS.10") under the following conditions: press surface temperature (molding temperature): 300°C, preheating time under press at a gauge pressure of 0.80 MPa: 1 minute, and pressing time after preheating at a gauge pressure of 5 MPa: 2 minutes.

[0103] Thereafter, material A was removed from the pressed laminate, and the first imide film was pulled out from material A. This resulted in a test piece in which the aforementioned contact surface (a region 50 mm from one end) became the adhesive surface. Note that in this test piece, the region that was not the adhesive surface was a free end (an open end as viewed from the adhesive surface).

[0104] (4-2. Measurement of Peel Strength) Using the test specimen obtained in 4-1 above, a peel adhesion strength test (90° peel) was performed in accordance with JIS K 6854-1:1999. The tensile tester used was an "ASG-X" manufactured by Shimazu Corporation. The test specimen was fixed to a SUS plate using adhesive tape ("Hyper Joint" manufactured by Nitto Denko Corporation), and the test specimen fixed to the SUS plate was fixed to a tensile tester. During the tensile test, the open end of the test specimen was gripped with a gripper attached to the tensile tester. The gripping movement speed of the tensile tester was 50 mm per minute. The maximum peel force [N / 10 mm] was then determined from the peel strength [N / 10 mm] obtained as a result of the peel adhesion strength test.

[0105] The test results are shown in Table 1 below.

[0106] In Table 1, "CF" means "T700S C 12K 50C" carbon fiber manufactured by Toray Industries, Inc., "Vf" is the fiber volume content (%), and "Rku" is the surface kurtosis with a normal distribution of 3.0.

[0107] From Table 1, it can be seen that composite materials having a surface kurtosis Rku value of 3.0 or more have a large maximum peel strength value and are excellent in peel strength when used in layers.

[0108] On the other hand, it was found that composite materials with a surface kurtosis Rku value of less than 3.0 have a small maximum peel strength, and the peel strength when used in layers is not sufficiently excellent.

[0109] The composite material and molded article of the present invention are useful in various applications where peel strength is required when used in layers, and are particularly useful as UD tapes or organosheets.

Claims

1. A composite material comprising a thermoplastic resin and continuous fibers, The fibers constituting the continuous fiber include at least a group of fibers aligned along a first fiber direction in one direction, A composite material wherein at least one of the first and second main surfaces of the composite material has a surface curtosis (Rku) of 3.0 or more in a direction intersecting the first fiber direction.

2. The composite material according to claim 1, wherein the continuous fibers are unidirectional fibers oriented only in the first fiber direction.

3. The composite material according to claim 1, wherein the thermoplastic resin includes a polyamide resin.

4. The composite material according to claim 3, wherein the polyamide includes a semi-aromatic polyamide resin.

5. The composite material according to claim 1, wherein the continuous fiber includes at least one selected from the group consisting of carbon fiber, glass fiber, ceramic fiber, synthetic fiber, natural fiber, and metal fiber.

6. The composite material according to claim 1, wherein the continuous fibers include carbon fibers.

7. The composite material according to claim 1, wherein the fiber volume content (Vf) of the composite material is 30% or more and 70% or less.

8. The composite material according to claim 1, wherein the thickness of the composite material is 0.10 mm or more and 0.30 mm or less.

9. A molded article formed from a composite material according to any one of claims 1 to 8.

10. A method for producing a composite material comprising a thermoplastic resin and continuous fibers, Mixing a molten thermoplastic resin with continuous fibers, and transporting the resulting molten material at a temperature higher than the glass transition temperature of the thermoplastic resin, and A method for producing a composite material, comprising bringing the discharged molten material into contact with a cooling body with a smooth surface within 5 seconds, cooling the molten material to a temperature lower than the glass transition temperature of the thermoplastic resin, and obtaining a composite material.

11. The method for manufacturing a composite material according to claim 10, wherein the molten material is cooled using a cooling roll as the cooling body.

12. A method for manufacturing a composite material according to claim 11, wherein a gaseous coolant is brought into contact with the surface of the molten material opposite to the surface of the molten material that is in contact with the cooling roll to cool it.