JP7501232B2 - Laminate, and member and resin composition used in said laminate - Google Patents

Description

The present invention relates to a laminate, and a member and a resin composition used in the laminate.

Conventionally, curable resin composite materials, which are made by compounding curable resins with reinforcing fibers such as carbon fiber and glass fiber to improve their strength, are lightweight and have excellent strength, and are therefore used as components in the fields of electrical and electronic equipment, industrial fields such as automobiles and aircraft, and the construction field.

For example, Patent Document 1 discloses a composite material obtained by alternately laminating prepreg layers made of reinforcing fibers and a thermosetting resin and layers made of an ethylene-unsaturated carboxylic acid-unsaturated ester copolymer or an ionomer thereof, followed by heating and curing, and describes that a composite material can be obtained which has excellent interlayer adhesion as well as excellent vibration damping properties, penetration impact strength, etc.
Furthermore, Patent Document 2 discloses a high-performance composite characterized by being formed by laminating, in a bonded or non-bonded state, a hard composite made of high-strength reinforcing fibers and a thermosetting resin, and a soft composite made of a fabric made of high-strength, high-elasticity fibers impregnated with or bonded to a thermoplastic resin. It describes that any impact that cannot be absorbed by the hard composite can be absorbed by the fabric of the soft composite, and therefore the composite constituent materials will not fly apart due to the impact.

Japanese Patent Application Laid-Open No. 11-34230 JP 2007-283758 A

However, the composite material described in Patent Document 1 and the high-performance composite described in Patent Document 2 have the problem of poor heat resistance because the layers between the prepreg layers or the soft composite contain a thermoplastic resin.

The present invention was made in consideration of the existence of the above problems, and aims to provide a laminate having excellent impact resistance and heat resistance, as well as a member and a resin composition for use in the laminate.

The present inventors have found that the above problems can be solved by adopting the following configuration.
That is, the present invention relates to the following [1] to [27].
[1] A laminate having a fiber-reinforced resin layer (A) containing a resin component (a-1) and a reinforcing fiber (a-2), and a curable resin layer (B) containing an elastic curable resin (b-1).
[2] The laminate according to the above [1], wherein the curable resin layer (B) has a tensile elongation of 50% or more.
[3] The laminate according to the above [1] or [2], wherein the tensile elongation of the raw material of the elastic curable resin (b-1) constituting the curable resin layer (B) is 50% or more.
[4] The laminate according to any one of the above [1] to [3], wherein the curable resin layer (B) has a tensile storage modulus of 1×10 ⁴ to 6×10 ⁷ Pa at 100° C. and 200° C.
[5] The laminate according to any one of the above [1] to [4], wherein the raw material of the elastic curable resin (b-1) constituting the curable resin layer (B) has a tensile storage modulus of 1×10 ⁴ to 6×10 ⁷ Pa at 100° C. and 200° C.
[6] The laminate according to any one of the above [1] to [5], wherein the elastic curable resin (b-1) is an epoxy resin.
[7] The laminate according to any one of the above [1] to [6], wherein the thickness of the curable resin layer (B) is 10 μm or more and 1 mm or less.
[8] The laminate according to any one of the above [1] to [7], wherein the thickness ratio of the curable resin layer (B) in the laminate is 5% or more and 70% or less.
[9] The laminate according to any one of the above [1] to [8], wherein the curable resin layer (B) is present at least in an area within 40% of the thickness of the laminate from the surface of the laminate.
[10] The laminate according to any one of the above [1] to [9], wherein the thickness of the curable resin layer (B) present in a region within 1 mm from the surface of the laminate is 10 μm or more and 800 μm or less.
[11] The laminate according to any one of the above [1] to [10], wherein the curable resin layer (B) is a cured product obtained by curing an epoxy resin composition containing an epoxy resin and a polyetheramine and/or a curing agent having an alicyclic structure.
[12] The laminate according to any one of the above [1] to [11], wherein the curable resin layer (B) is a cured product obtained by curing an epoxy resin composition containing an epoxy resin and an alicyclic polyamine.
[13] The laminate according to any one of the above [6] to [12], wherein the epoxy resin has a block structure of a rigid component and a flexible component.
[14] The laminate according to any one of the above [1] to [13], wherein the resin component (a-1) is an epoxy resin.
[15] The laminate according to any one of the above [1] to [14], wherein the fiber reinforced resin layer (A) is a cured product obtained by curing a prepreg or a semipreg.
[16] A mobile object such as an aircraft, an automobile, a ship, or a railroad car, a sporting goods, a home electric appliance, or a building material, comprising the laminate according to any one of the above [1] to [15].
[17] A member used in a laminate of a fiber-reinforced resin composite containing a resin component (a-1) and reinforcing fibers (a-2), the member containing an elastic curable resin (b-1) as the resin component.
[18] The member according to the above [17], which is a sheet.
[19] The member according to [17] or [18] above, having a tensile elongation of 50% or more.
[20] The member according to any one of the above [17] to [19], having a tensile storage modulus of 1×10 ⁴ to 6×10 ⁷ Pa at 100° C. and 200° C.
[21] The member according to any one of [17] to [20] above, wherein the fiber reinforced resin composite is a prepreg and/or a semipreg.
[22] A resin composition used for a laminate of a fiber-reinforced resin composite containing a resin component (a-1) and reinforcing fibers (a-2), the resin composition comprising an epoxy resin having a block structure of a rigid component and a flexible component.
[23] The resin composition according to the above [22], wherein the fiber-reinforced resin composite is a prepreg and/or a semipreg.
[24] A method for producing a laminate, comprising the steps of laminating a prepreg and/or semipreg and the member according to any one of the above [17] to [21], and curing the prepreg and/or semipreg.
[25] A method for producing a laminate, comprising the steps of laminating a fiber-reinforced resin composite and the resin composition according to the above [22] or [23], and curing the resin composition.
[26] A method for producing a laminate, comprising the steps of laminating a prepreg and/or semipreg and the resin composition according to the above item [22] or [23], and curing the prepreg and/or semipreg and the resin composition.
[27] A method for producing a laminate, comprising: a step of curing a prepreg and/or semipreg; a step of laminating a cured product of the prepreg and/or semipreg with the resin composition described in [22] or [23] above; and a step of curing the resin composition.

The present invention provides a laminate having excellent impact resistance and heat resistance, as well as a member and a resin composition for use in the laminate.

[Laminate]
The laminate of the present invention (hereinafter also simply referred to as "laminate") has a fiber-reinforced resin layer (A) containing a resin component (a-1) and reinforcing fibers (a-2), and a curable resin layer (B) containing an elastic curable resin (b-1).

<Fiber reinforced resin layer (A)>
The fiber reinforced resin layer (A) contains a resin component (a-1) and reinforcing fibers (a-2).

(Resin component (a-1))
The resin component (a-1) is not particularly limited, and may be a curable resin or a thermoplastic resin, but is preferably a curable resin from the viewpoint of heat resistance, and more preferably a thermosetting resin from the viewpoint of ease of application to the molding process. Examples of thermosetting resins include epoxy resins, phenolic resins, unsaturated imide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins. Among these, the resin component (a-1) is preferably an epoxy resin from the viewpoints of heat resistance, adhesion to the curable resin layer (B), electrical insulation, chemical resistance, corrosion resistance, and the like. These may be used alone or in combination of two or more.

(Reinforcing fiber (a-2))
Examples of the reinforcing fiber (a-2) include, but are not limited to, inorganic fibers such as carbon fibers, glass fibers, boron fibers, and alumina fibers, organic fibers such as liquid crystal polymer fibers, polyethylene fibers, aramid fibers, and polyparaphenylenebenzoxazole fibers, and metal fibers such as aluminum fibers, magnesium fibers, titanium fibers, SUS fibers, copper fibers, and metal-coated carbon fibers. Among these, the reinforcing fiber (a-2) is preferably at least one selected from the group consisting of carbon fibers and glass fibers from the viewpoint of rigidity, and is more preferably carbon fiber from the viewpoints of lightness and rigidity.

Examples of the carbon fibers include polyacrylonitrile (PAN)-based carbon fibers, petroleum-based, coal-based, and other pitch-based carbon fibers, rayon-based carbon fibers, and lignin-based carbon fibers, and any of these carbon fibers can be used. In particular, PAN-based carbon fibers made from PAN as a raw material, strands or tows of 12,000 to 48,000 filaments, are preferred because of their excellent productivity and mechanical properties on an industrial scale.

The reinforcing fibers may be continuous or discontinuous, but are preferably continuous. When the reinforcing fibers are discontinuous, such as chopped strands or nonwoven fabrics, as described below, the number-average fiber length is usually 0.5 mm or more, preferably 1 mm or more, more preferably 3 mm or more, even more preferably 5 mm or more, particularly preferably 10 mm or more, especially preferably 30 mm or more, and most preferably 50 mm or more. By setting the number-average fiber length to the lower limit or more, the mechanical properties of the resulting laminate tend to be sufficient. The upper limit of the number-average fiber length is not particularly limited, but is preferably 500 mm, more preferably 300 mm, and even more preferably 150 mm. By setting the number-average fiber length to the upper limit or less, the reinforcing fibers can be sufficiently filled into the complex shaped portion when the laminate is used to form a final product, particularly a final product with a complex shape, and the occurrence of a decrease in strength in the relevant portion tends to be easily suppressed.

The shape of the reinforcing fibers is not particularly limited, and can be appropriately selected from among fiber bundles such as chopped strands and rovings, woven fabrics such as plain weave and twill weave, knitted fabrics, nonwoven fabrics, fiber papers, and reinforcing fiber sheets such as UD materials (unidirectional materials), as needed.
Among these, from the viewpoint of mechanical properties such as tensile modulus and tensile strength, continuous fibers such as woven fabrics, knitted fabrics, and UD materials are preferred.

The method for forming the fiber-reinforced resin layer (A) by combining the resin component (a-1) and the reinforcing fiber (a-2) is not particularly limited, and any conventionally known method can be used.
For example, when the resin component (a-1) is a curable resin, a method is preferred in which a prepreg in which the reinforcing fiber (a-2) is impregnated with the resin component (a-1), or a so-called semipreg in which the reinforcing fiber (a-2) is partially impregnated (semi-impregnated) with the resin component (a-1) and the amount of voids is controlled, is cured by heat or the like to form the fiber-reinforced resin layer (A). That is, the fiber-reinforced resin layer (A) is preferably formed by curing a prepreg or semipreg.
When the resin component (a-1) is a thermoplastic resin, the resin component (a-1) and the reinforcing fiber (a-2) are combined and molded into a fiber-reinforced film, fiber-reinforced sheet, fiber-reinforced plate, etc. by employing extrusion molding, injection molding, vacuum molding, compressed air molding, press molding, etc. to form the fiber-reinforced resin layer (A). The fiber-reinforced resin layer (A) can also be formed by using a so-called mixed mat consisting of the reinforcing fiber (a-2) and the thermoplastic resin fiber and press molding at a temperature equal to or higher than the flow initiation temperature of the thermoplastic resin fiber.

From the viewpoints of elastic modulus and strength, the proportion of reinforcing fiber (a-2) in the fiber-reinforced resin layer (A) is preferably 20 vol.% or more, more preferably 30 vol.% or more, even more preferably 40 vol.% or more, and is preferably 90 vol.% or less, more preferably 80 vol.% or less.

As the prepreg used for the fiber-reinforced resin layer (A), a commercially available product can be used, for example, prepregs such as "TR3110 381GMX", "TR3523 381GMX", "TR6110H 331GMP", "TR350C 175S", and "HSX350C110S" manufactured by Mitsubishi Chemical Corporation can be used.

<Curable resin layer (B)>
The curable resin layer (B) contains an elastic curable resin (b-1). Since the curable resin layer (B) contains the elastic curable resin (b-1), the laminate of the present invention is excellent in impact resistance and heat resistance, and further in vibration damping properties.

(Elastic Curable Resin (b-1))
The elastic curable resin (b-1) is not particularly limited as long as the tensile elongation of the curable resin layer (B) is preferably 50% or more, and the curable resin layer (B) has elasticity. Here, the term "elastic curable resin" refers to, for example, an elastic curable resin sheet or film that can be visually confirmed to expand and contract when pulled by hand.
The elastic curable resin (b-1) is preferably an epoxy resin, a urethane resin, or a silicone resin, and more preferably an epoxy resin from the viewpoints of heat resistance and adhesion to the fiber-reinforced resin layer (A). In addition, the elastic curable resin (b-1) is preferably a thermosetting resin from the viewpoint of ease of application to the molding process.
The curable resin layer (B) may contain a resin other than the elastic curable resin (b-1). In that case, the proportion of the elastic curable resin (b-1) in the curable resin layer (B) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more.

The elastic curable resin (b-1) can be obtained, for example, by thermally curing an elastic curable resin composition containing a chemical structure having elasticity. More specifically, for example, it can be obtained by thermally curing an elastic curable resin composition containing a curing agent and a base agent containing a resin having a chemical structure that becomes an elastic curable resin having elasticity after curing. In addition, as another method, it can also be obtained by curing a resin raw material that becomes an elastic curable resin after curing with radiation such as gamma rays, electron beams, and X-rays.
Hereinafter, the epoxy resin preferably used as the elastic curable resin (b-1) will be described.
In the present invention, the term "epoxy resin" refers to both the raw resin before curing and the resin after curing (cured product). Since the epoxy groups are consumed by the curing reaction, the cured resin may not have epoxy groups (epoxy structures).

<Epoxy resin>
The epoxy resin, which is a preferred resin for the elastic curable resin (b-1), is more preferably an epoxy resin having a block structure of a rigid component and a flexible component. By having such a structure, it is easy for the resin to have excellent elasticity.
The epoxy resin can be obtained, for example, by curing an epoxy resin composition containing at least a base agent and a curing agent. Hereinafter, the epoxy resin composition before curing will be described.

<Epoxy resin composition>
The epoxy resin composition preferably contains an epoxy resin as a base component, and more preferably contains an epoxy resin having a block structure of a rigid component and a flexible component (hereinafter referred to as "epoxy resin (α)").

(Epoxy resin (α))
The rigid component of the epoxy resin preferably contains a ring structure having aromaticity, for example, a condensed aromatic ring structure such as a benzene ring, a naphthalene ring, an anthracene ring, or a pyrene ring, a structure containing a large number of aromatic ring structures such as a biphenol ring, a cardo structure, or a fluorene ring, or a heterocyclic structure such as a pyrrole ring or a thiophene ring.
The softening component preferably contains an aliphatic hydrocarbon, for example an alkylene group having 1 to 8 carbon atoms, an ethylene glycol group, a propylene glycol group, or a butylene glycol group.
When the epoxy resin composition contains such an epoxy resin (α), flexibility tends to be imparted to the curable resin layer (B) after curing.

The epoxy resin (α) does not necessarily have to have an epoxy group or an epoxy group-derived structure in both the rigid component and the flexible component. In other words, the epoxy resin (α) only needs to have an epoxy group or an epoxy group-derived structure in at least one of the rigid component and the flexible component. From the viewpoint of imparting flexibility while retaining the inherent properties of epoxy resins, such as excellent heat resistance and mechanical strength, it is preferable that only one of the rigid component and the flexible component has an epoxy group or an epoxy group-derived structure.

Specific examples of the epoxy resin (α) include a copolymer of bisphenol F and 1,6-hexanediol diglycidyl ether, a copolymer of 1,6-hexanediol and bisphenol F diglycidyl ether, a copolymer of bisphenol F and 1,4-butanediol diglycidyl ether, a copolymer of 1,4-butanediol and bisphenol F diglycidyl ether, a copolymer of bisphenol A and 1,6-hexanediol diglycidyl ether, a copolymer of 1,6-hexanediol and bisphenol A diglycidyl ether, a copolymer of bisphenol A and 1,4-butanediol diglycidyl ether, a copolymer of 1,4-butanediol and bisphenol A diglycidyl ether, a copolymer of tetramethylbiphenol and 1,6-hexanediol diglycidyl ether, a copolymer of 1,6-hexanediol and tetramethylbiphenol diglycidyl ether, a copolymer of tetramethylbiphenol and 1,4-butanediol diglycidyl ether, a copolymer of 1,4-butanediol and tetramethylbiphenol diglycidyl ether, a copolymer of tetramethylbiphenol and 1,4-butanediol ...1,4-butanediol and tetramethylbiphenol diglycidyl ether, and biglycidyl ether. Copolymer of phenol and 1,6-hexanediol diglycidyl ether, copolymer of 1,6-hexanediol and biphenol diglycidyl ether, copolymer of biphenol and 1,4-butanediol diglycidyl ether, copolymer of 1,4-butanediol and biphenol diglycidyl ether, copolymer of 1,4-naphthalenediol and 1,6-hexanediol diglycidyl ether, copolymer of 1,6-hexanediol and 1,4-naphthalenediol diglycidyl ether, copolymer of 1,4-naphthalenediol and 1,4 copolymers of 1,4-butanediol and 1,4-naphthalenediol diglycidyl ether, copolymers of 1,6-naphthalenediol and 1,6-hexanediol diglycidyl ether, copolymers of 1,6-hexanediol and 1,6-naphthalenediol diglycidyl ether, copolymers of 1,6-naphthalenediol and 1,4-butanediol diglycidyl ether, copolymers of 1,4-butanediol and 1,6-naphthalenedi ... and copolymers of 1,4-butanediol and 1,6-naphthalenediol diglycidyl ether.
These may be used alone or in any combination and ratio of two or more. Among these, from the viewpoint of imparting flexibility, it is preferable that the epoxy resin (α) contains a copolymer of bisphenol F and 1,6-hexanediol diglycidyl ether.

The epoxy resin composition may contain an epoxy resin other than the above-mentioned epoxy resin (α) (hereinafter referred to as "epoxy resin (β)").

(Epoxy resin (β))
Examples of the epoxy resin (β) include various epoxy resins such as glycidyl ether type epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, biphenyl type epoxy resins, phenol novolac type epoxy resins, and cresol novolac type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, linear aliphatic epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins.
These may be used alone or in any combination and ratio of two or more kinds.

The epoxy resin composition may contain only epoxy resin (α), may contain both epoxy resin (α) and epoxy resin (β), or may contain only epoxy resin (β).

When the epoxy resin composition contains the epoxy resin (α) and the epoxy resin (β), the proportion of the epoxy resin (β) in the total epoxy components as solid contents in the epoxy resin composition is preferably 5 mass% or more, more preferably 10 mass% or more. The upper limit is preferably 95 mass%, more preferably 90 mass%.
By making the proportion of the epoxy resin (β) equal to or greater than the above lower limit, the physical property improving effect of blending the epoxy resin (β) can be sufficiently obtained, whereas by making the proportion of the epoxy resin (β) equal to or less than the above upper limit, the effect of imparting flexibility and improving flexibility by the epoxy resin (α) can be sufficiently obtained.

In the present invention, the term "solid content" means components excluding the solvent, and includes not only solid epoxy resins or epoxy compounds, but also semi-solid and viscous liquid substances.
Moreover, the term "total epoxy components" means the sum of the epoxy resin (α) and the above-mentioned epoxy resin (β).

(Hardening agent)
The curing agent is one that contributes to the crosslinking reaction between the epoxy group of the epoxy resin and a group reactive with the epoxy group. There are no particular limitations on the curing agent, and any agent generally known as an epoxy resin curing agent can be used.
Examples of such curing agents include phenol-based curing agents, amine-based curing agents such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, acid anhydride-based curing agents, amide-based curing agents, tertiary amines, imidazole and its derivatives, organic phosphines, phosphonium salts, tetraphenylboron salts, organic acid dihydrazides, boron halide amine complexes, polymercaptan-based curing agents, isocyanate-based curing agents, and blocked isocyanate-based curing agents.
These may be used alone or in any combination and ratio of two or more. Among these, from the viewpoints of high transparency and little coloring, a curing agent having an alicyclic structure is preferred as the curing agent.

The curing agent having an alicyclic structure may be any substance that has an alicyclic structure and contributes to the crosslinking reaction and/or the chain extension reaction between the epoxy groups of the epoxy resin.
Specific examples include alicyclic polyamines and alicyclic acid anhydrides.
More specifically, examples of the alicyclic polyamine include 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undec-7-ene, N,N'-dimethylpiperazine, N-aminoethylpiperazine, menthene diamine, isophorone diamine, hexamethylenetetramine, methylenebis(cyclohexanamine), 1,3-bis(aminomethyl)cyclohexane, norbornene diamine, 1,2-diaminocyclohexane, and modified alicyclic polyamines obtained by epoxy-modifying, ethylene oxide-modifying, dimer acid-modifying, Mannich-modifying, Michael addition-modifying, thiourea condensing, or ketiminizing these alicyclic polyamines. Examples of the alicyclic acid anhydride include hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, and the like.
Of these, alicyclic polyamines are preferred, and among these, isophoronediamine, hexamethylenetetramine, methylenebis(cyclohexanamine), 1,3-bis(aminomethyl)cyclohexane, norbornenediamine, 1,2-diaminocyclohexane, and modified products thereof are particularly preferred.

Curing agents having an alicyclic structure can be commercially available products, such as "jER Cure 113" and "jER Cure ST-14" manufactured by Mitsubishi Chemical Corporation, and "Rikacid MH-700" manufactured by New Japan Chemical Co., Ltd.

The content of the curing agent in the epoxy resin composition (when a curing agent other than the curing agent having an alicyclic structure is used, the total content of the curing agent having an alicyclic structure and the other curing agent) is preferably 0.1 to 100 parts by mass, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, even more preferably 40 parts by mass or less, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more, per 100 parts by mass of the epoxy resin (total content of all epoxy components).

(solvent)
In order to appropriately adjust the viscosity during handling when forming the curable resin layer (B), the epoxy resin composition may be diluted with a solvent. The solvent is used to ensure the handleability and workability during molding of the curable resin layer (B), and there is no particular limit to the amount used.
In the present invention, the terms "solvent" and "solvent" are used to distinguish between the two depending on the form of use, but the same or different substances may be used independently.

Examples of solvents include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol, etc., and these solvents can also be used as a mixed solvent of two or more of them as appropriate.

(Other ingredients)
The epoxy resin composition may contain other components in addition to the components listed above. The other components may be used in appropriate combinations depending on the desired physical properties of the epoxy resin composition.

For example, an inorganic filler can be further added to improve various properties, such as the effect of reducing the cure shrinkage rate of the curable resin layer (B) after curing, the effect of reducing the thermal expansion coefficient, etc. In addition, organic fillers such as rubber particles and acrylic particles may also be added to the epoxy resin composition to impart toughness.

Examples of inorganic fillers include powdered reinforcing agents and fillers, such as metal oxides such as aluminum oxide and magnesium oxide, metal carbonates such as calcium carbonate and magnesium carbonate, silicon compounds such as diatomaceous earth powder, basic magnesium silicate, calcined clay, finely powdered silica, fused silica, and zeolite, metal hydroxides such as aluminum hydroxide, kaolin, mica, quartz powder, graphite, carbon black, carbon nanotubes, molybdenum disulfide, boron nitride, and aluminum nitride.

It is also possible to add fibrous reinforcing agents or fillers to the epoxy resin composition. Examples include glass fiber, ceramic fiber, carbon fiber, alumina fiber, silicon carbide fiber, boron fiber, aramid fiber, cellulose nanofiber, and cellulose nanocrystal. Cloth or nonwoven fabric made of organic or inorganic fibers can also be used.

These fillers, fibers, cloths, and nonwoven fabrics can also be used after surface treatment, such as treatment with a silane coupling agent, titanate coupling agent, aluminate coupling agent, or primer.

When inorganic fillers, fibrous reinforcing agents, or fillers are added, the total amount of these added is preferably 900 parts by mass or less, more preferably 700 parts by mass or less, and even more preferably 500 parts by mass or less, per 100 parts by mass of the sum of the epoxy resin and the curing agent. There is no particular limit to the lower limit, but 1 part by mass is preferred, 5 parts by mass is more preferred, and 10 parts by mass is even more preferred.

The epoxy resin composition may contain, as required, a coupling agent, a plasticizer, a diluent, a flexibility imparting agent, a dispersant, a wetting agent, a colorant, a pigment, an ultraviolet absorber, a light stabilizer such as a hindered amine-based light stabilizer, an antioxidant, a defoamer, a release agent, a flow adjuster, and the like.
The amount of these components is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the sum of the epoxy resin and the curing agent. The lower limit is not particularly limited, but is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, and even more preferably 1 part by mass.

In order to improve the properties of the resin in the curable resin layer (B), various curable monomers, oligomers and synthetic resins may be blended into the epoxy resin composition as necessary.
For example, cyanate ester resin, acrylic resin, silicone resin, polyester resin, etc. may be used alone or in combination of two or more thereof.
The blending ratio of these resins is an amount within a range that does not impair the inherent properties of the epoxy resin, i.e., for 100 parts by mass of the sum of the epoxy resin and the curing agent, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. The lower limit is not particularly limited, but is preferably 1 part by mass, more preferably 5 parts by mass, and even more preferably 10 parts by mass.

Specifically, the curable resin layer (B) is preferably a cured product obtained by curing an epoxy resin composition containing an epoxy resin and a polyetheramine and/or a curing agent having an alicyclic structure, and more preferably a cured product obtained by curing an epoxy resin composition containing an epoxy resin and an alicyclic polyamine.

<Method for producing curable resin layer (B)>
The method of forming the curable resin layer (B) is not particularly limited, and for example, a method of curing the elastic curable resin composition containing the above-mentioned main agent and curing agent, etc., can be mentioned as a preferred embodiment. The term "curing" as used herein means curing the elastic curable resin composition by heat, light, electron beam, etc. In addition, for example, it also includes a case where the elastic curable resin composition before curing is stored for a long period of time and gradually hardens due to the influence of heat or light over time. The degree of curing is not particularly limited, and may be a completely or nearly completely cured product or a semi-cured product. The degree of curing may be appropriately adjusted depending on the purpose, application, etc.
The curable resin layer (B) can be produced by curing the elastic curable resin composition in a state in which the composition is adjusted to a sheet or film (hereinafter referred to as "sheet, etc.") having a predetermined thickness. Alternatively, the curable resin layer (B) can be produced by forming a semi-cured product obtained from the elastic curable resin composition into a sheet, etc. having a predetermined thickness and further curing the semi-cured product.
The method for preparing the sheet or the like is not particularly limited, but examples thereof include a method of applying an elastic curable resin composition onto a carrier sheet, curing the resin composition to form an elastic curable resin sheet or the like, and then peeling off the carrier sheet to obtain an elastic curable resin sheet or the like; a method of applying an elastic curable resin composition onto a first carrier sheet, laminating a second carrier sheet to the surface of the resin composition opposite to the surface on which the first carrier sheet is provided, curing the resin composition to form an elastic curable resin sheet or the like, and then peeling off both carrier sheets.

In general, a "sheet" is defined in JIS as a thin, flat product whose thickness is small relative to its length and width, and a "film" is generally a thin, flat product whose thickness is extremely small compared to its length and width, with an arbitrarily limited maximum thickness, and is usually supplied in roll form (JIS K 6900:1994). However, the boundary between "sheet" and "film" is unclear, and since there is no need to distinguish between the two in the present invention, in the context of the present invention, the term "film" is intended to include "sheet", and the term "sheet" is intended to include "film".

The method for curing the elastic curable resin composition varies depending on the ingredients and amounts of the elastic curable resin composition, or the shape of the composition (for example, the thickness of a sheet or film), but typically involves heating at 23 to 200°C for 5 minutes to 24 hours. This heating is preferably carried out as a one-stage process in which a primary heating is performed at 23 to 160°C for 5 minutes to 24 hours, a two-stage process in which, in addition to the one-stage process, a secondary heating is performed at 80 to 200°C, which is 40 to 177°C higher than the primary heating temperature, for 5 minutes to 24 hours, or a three-stage process in which, in addition to the two-stage process, a tertiary heating is performed at 100 to 200°C, which is higher than the secondary heating temperature, for 5 minutes to 24 hours, in order to reduce curing defects.

When producing the curable resin layer (B) as a semi-cured product, the curing reaction of the elastic curable resin composition may be allowed to proceed to an extent that the shape can be maintained by heating or the like. If the elastic curable resin composition contains a solvent, most of the solvent is removed by heating, reducing pressure, air drying, or other techniques, but 5% by mass or less of the solvent may remain in the semi-cured product.

In this specification, the sheet, film, or other member of the elastic curable resin (b-1) used as the curable resin layer (B) is referred to as the elastic curable resin (b-1) raw material.

<Physical properties of the curable resin layer (B) or the raw material of the elastic curable resin (b-1) constituting the curable resin layer (B)>
(Tensile elongation)
From the viewpoint of improving the impact resistance of the laminate using the curable resin layer (B) having excellent elasticity, the tensile elongation of the curable resin layer (B) is preferably 50% or more, more preferably 100% or more, even more preferably 150% or more, still more preferably 200% or more, and even more preferably 300% or more, and the upper limit thereof is preferably 500%.
The tensile elongation (tensile elongation at break) of the curable resin layer (B) can be determined by scraping off layers other than the curable resin layer (B) from the laminate, performing a tensile test in accordance with JIS K 7127:1999 at a test speed of 200 mm/min in an environment of 23°C and 50% RH, and measuring the elongation at tensile break.

The elastic curable resin (b-1) raw material constituting the curable resin layer (B) has a tensile elongation (tensile elongation at break) measured in accordance with JIS K 7127:1999 at a test speed of 200 mm/min under an environment of 23°C and 50% RH, from the same viewpoints as above, of preferably 50% or more, more preferably 100% or more, even more preferably 150% or more, still more preferably 200% or more, and even more preferably 300% or more, and the upper limit is preferably 500%.
The tensile elongation of the raw material of the elastic curable resin layer (b-1) constituting the curable resin layer (B) can be specifically measured by the method described in the Examples.

(Tensile storage modulus)
From the viewpoint of flexibility, the tensile storage modulus of the curable resin layer (B) at 100°C and 200°C is preferably 1x10 ⁴ to 6x10 ⁷ Pa, more preferably 6x10 ⁴ to 1x10 ⁷ Pa, and even more preferably 4x10 ⁵ to 9x10 ⁶ Pa. Particularly preferred is a tensile modulus of 1x10 ⁴ to 6x10 ⁷ Pa at 100 to 200°C. Note that "tensile storage modulus of 1x10 ⁴ to 6x10 ⁷ Pa at 100 to 200°C" means that the tensile storage modulus is maintained at 1x10 ⁴ Pa or more and 6x10 ⁷ Pa or less over the entire temperature range of 100 to 200°C. Other numerical ranges are also treated in the same manner.
The tensile storage modulus of the curable resin layer (B) at 100 to 200 ° C. is obtained by scraping off layers other than the curable resin layer (B) from the laminate, cutting out a test piece with a width of 10 mm and a length of 50 mm, and measuring the test piece by the dynamic viscoelasticity measurement method described in JIS K 7244-4:1999 using a dynamic viscoelasticity measuring device (for example, "DVA-200" manufactured by IT Measurement & Control Co., Ltd.) under the measurement conditions of a frequency of 1 Hz, a heating rate of 3 ° C. / min, and a double-support tensile mode.

The tensile storage modulus at 100°C and 200°C of the elastic curable resin (b-1) raw material constituting the curable resin layer (B) is preferably ^1x104 to ^6x107 Pa, more preferably ^6x104 to ^1x107 Pa, and even more preferably ^4x105 to ^9x106 Pa, from the same viewpoint as above. Particularly preferred is a tensile modulus at 100 to 200°C of 1x104 to ^6x107 Pa. Note that "tensile storage modulus at ¹⁰⁰ to 200°C of ^1x104 to ^6x107 Pa" means that the tensile storage modulus is maintained at ^1x104 Pa or more and ^6x107 Pa or less in the entire temperature range of 100 to 200°C.
The tensile storage modulus of the raw material of the elastic curable resin (b-1) constituting the curable resin layer (B) can be measured by the method described in the Examples.

(Glass-transition temperature)
The glass transition temperature of the curable resin layer (B) measured by a dynamic viscoelasticity measurement method in accordance with JIS K 7244-4:1999 is, from the viewpoint of obtaining a curable resin layer (B) having excellent elasticity, preferably 100°C or lower, more preferably 80°C or lower, even more preferably 60°C or lower, and still more preferably 40°C or lower. The lower limit is not particularly limited, but is preferably -100°C, more preferably -80°C, and even more preferably -60°C.
The glass transition temperature refers to the peak top temperature of the tensile loss factor (tan δ) calculated from the loss modulus E″ and storage modulus E′ in dynamic viscoelasticity measurement. When two or more peaks are present, the peak top temperature having the larger peak area is taken as the glass transition temperature, and the same applies below.

Further, the glass transition temperature of the curable resin layer (B) measured by a differential scanning calorimeter in accordance with JIS K 7121:2012 is, from the viewpoint of obtaining a curable resin layer (B) having excellent elasticity, preferably 90°C or less, more preferably 70°C or less, even more preferably 50°C or less, and still more preferably 30°C or less. The lower limit is not particularly limited, but is preferably -110°C, more preferably -90°C, and even more preferably -70°C.
The dynamic viscoelasticity measurement and the glass transition temperature of the curable resin layer (B) by differential scanning calorimetry can be measured under the above-mentioned conditions using a sample obtained by scraping off layers other than the curable resin layer (B) from the laminate.

The glass transition temperature of the elastic curable resin (b-1) raw material constituting the curable resin layer (B), measured by a dynamic viscoelasticity measurement method in accordance with JIS K 7244-4:1999, is preferably 100°C or lower, more preferably 80°C or lower, even more preferably 60°C or lower, and even more preferably 40°C or lower, from the same viewpoint as above, and the lower limit is not particularly limited, but is preferably -100°C, more preferably -80°C, and even more preferably -60°C.

In addition, the glass transition temperature of the elastic curable resin (b-1) raw material constituting the curable resin layer (B) measured by a differential scanning calorimeter in accordance with JIS K 7121:2012 is preferably 90°C or less, more preferably 70°C or less, even more preferably 50°C or less, and even more preferably 30°C or less, from the viewpoint of obtaining a curable resin layer (B) having excellent elasticity. The lower limit is not particularly limited, but is preferably -110°C, more preferably -90°C, and even more preferably -70°C.
The dynamic viscoelasticity measurement and the glass transition temperature by differential scanning calorimetry of the raw material of the elastic curable resin (b-1) constituting the curable resin layer (B) can be measured by the method described in the Examples.

(Maximum value of tensile loss factor (tan δ))
The maximum value of the tensile loss coefficient (tan δ) of the curable resin layer (B) measured by a dynamic viscoelasticity measurement method in accordance with JIS K 7244-4:1999 is, from the viewpoint of obtaining a curable resin layer (B) having excellent impact absorption, preferably 0.3 or more, more preferably 0.5 or more, even more preferably 1 or more, and still more preferably 1.5 or more. The larger the value, the better the impact absorption. The upper limit is not particularly limited, but is preferably 5.
The maximum value of the tensile loss coefficient (tan δ) of the curable resin layer (B) is obtained by scraping off layers other than the curable resin layer (B) from the laminate, cutting out a test piece with a width of 10 mm and a length of 50 mm, and measuring the test piece by the dynamic viscoelasticity measurement method described in JIS K 7244-4:1999 using a dynamic viscoelasticity measuring device (for example, "DVA-200" manufactured by IT Measurement & Control Co., Ltd.) under the measurement conditions of a frequency of 1 Hz, a heating rate of 3 ° C. / min, and a double-support tensile mode.

The maximum value of the tensile loss coefficient (tan δ) of the elastic curable resin (b-1) raw material constituting the curable resin layer (B), measured by a dynamic viscoelasticity measurement method in accordance with JIS K 7244-4:1999, is preferably 0.3 or more, more preferably 0.5 or more, even more preferably 1 or more, and even more preferably 1.5 or more, from the viewpoint of obtaining a curable resin layer (B) having excellent impact absorption. The larger the value, the better the impact absorption. The upper limit is not particularly limited, but is preferably 5.
The maximum value of the tensile loss factor (tan δ) of the raw material of the elastic curable resin (b-1) constituting the curable resin layer (B) can be measured by the method described in the Examples.

(thickness)
The thickness of the curable resin layer (B) is appropriately changed depending on the use of the laminate, but from the viewpoint of impact resistance, it is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, still more preferably 50 μm or more, and preferably 1 mm or less, more preferably 800 μm or less, even more preferably 700 μm or less, still more preferably 650 μm or less, particularly preferably 600 μm or less, and most preferably 550 μm or less.
From the viewpoint of impact resistance, the ratio of the thickness of the curable resin layer (B) in the laminate is preferably 5% or more, more preferably 8% or more, even more preferably 10% or more, and preferably 70% or less, more preferably 65% or less, even more preferably 60% or less. When there are a plurality of curable resin layers (B), the total thickness of these layers relative to the thickness of the laminate is the ratio of the thickness of the curable resin layer (B) in the laminate.
The thickness (average thickness) of the curable resin layer (B) and the laminate is measured by observing a cross section of the laminate under a microscope or the like, and is calculated as the arithmetic average thereof.

[Layer structure of laminate]
The curable resin layer (B) in the laminate is appropriately changed according to the use of the laminate, but from the viewpoint of impact resistance, it is preferable that it is present at least in the region within 40% of the thickness of the laminate from the surface of the laminate, more preferably at least in the region within 37% of the thickness of the laminate from the surface, even more preferably at least in the region within 35% of the thickness of the laminate from the surface, even more preferably at least in the region within 32% of the thickness of the laminate from the surface, and particularly preferably at least in the region within 30% of the thickness of the laminate from the surface.In addition, in the present invention, "surface of the laminate" means the surface opposite to the surface laminated with another layer in the two outermost layers of the laminate, and the laminate has two surfaces.
From the viewpoint of impact resistance, the outermost layer of the laminate is preferably a fiber-reinforced resin layer (A), but may be a curable resin layer (B) depending on the application of the laminate.

The thickness of the curable resin layer (B) present in an area within 40% of the thickness of the laminate from the surface of the laminate is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, even more preferably 50 μm or more, and preferably 1 mm or less, more preferably 800 μm or less, even more preferably 700 μm or less, even more preferably 650 μm or less, particularly preferably 600 μm or less, and most preferably 550 μm or less, from the viewpoint of impact resistance. In addition, when there are multiple curable resin layers (B) present in an area within 40% of the thickness of the laminate from the surface of the laminate, the total thickness of these layers is the thickness of the curable resin layer (B) present in an area within 40% of the thickness of the laminate from the surface of the laminate.

The curable resin layer (B) is preferably present in an area within 1 mm from the surface of the laminate, more preferably within 800 μm, even more preferably within 750 μm, even more preferably within 700 μm, particularly preferably within 650 μm, and most preferably within 600 μm.

The thickness of the curable resin layer (B) present in the region within 1 mm from the surface of the laminate is, from the viewpoint of impact resistance, preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, even more preferably 50 μm or more, and preferably 800 μm or less, more preferably 750 μm or less, even more preferably 700 μm or less, even more preferably 650 μm or less, particularly preferably 600 μm or less, and most preferably 550 μm or less. When multiple curable resin layers (B) are present in the region within 1 mm from the surface of the laminate, the total thickness of these layers is regarded as the thickness of the curable resin layer (B) present in the region within 1 mm from the surface of the laminate.

The laminate preferably has at least one curable resin layer (B) and at least two fiber-reinforced resin layers (A), and it is preferable that the curable resin layer (B) is disposed between the fiber-reinforced resin layers (A).
The laminate may be formed by alternately laminating a fiber-reinforced resin layer (A) and a curable resin layer (B), or may not be formed by alternately laminating a fiber-reinforced resin layer (A) and a curable resin layer (B).
From the viewpoint of impact resistance, the laminate has at least two fiber-reinforced resin layers (A) having a thickness of preferably 400 μm or less on both surfaces, and preferably has a curable resin layer (B) having the above-mentioned suitable thickness in a region within 40% of the thickness of the laminate from the surface of the laminate or within 1 mm from the surface of the laminate, and the remaining layers may be formed by laminating multiple layers of the fiber-reinforced resin layer (A). In addition, the laminate may have a symmetrical or asymmetrical layer structure of the fiber-reinforced resin layer (A) and the curable resin layer (B) from the center of the laminate to both surfaces in a cross-sectional view.
Specific examples of the layer structure of the laminate include A/B/A, A/B/A/B/A, A/B/A...A/B/A, A/A/B/A...A/B/A, A/A/B/A...A/B/A, etc., where the fiber reinforced resin layer (A) is "A" and the curable resin layer (B) is "B". In addition, other layers (C) other than the fiber reinforced resin layer (A) and the curable resin layer (B) may be appropriately included depending on the intended use, performance, etc.

The method for producing the laminate of the present invention is not particularly limited, and any known method can be used. For example, the following methods (i) to (iii) are preferred.
(i) A method of laminating a material such as a prepreg or semipreg (fiber reinforced resin composite) used for the fiber reinforced resin layer (A) and a material such as a sheet or film of the elastic curable resin (b-1) used for the curable resin layer (B), and curing and bonding the resin component by heat or the like to integrate them;
(ii) A method in which the elastic curable resin composition (uncured product) used in the curable resin layer (B) is laminated to a material (fiber-reinforced resin composite) such as a prepreg or semipreg used in the fiber-reinforced resin layer (A) by a method such as coating, and the resin component is cured and bonded by heat or the like to form an integrated structure;
(iii) A method in which a material such as a prepreg or semipreg (fiber-reinforced resin composite) is cured in advance to obtain a fiber-reinforced resin layer (A), and then an elastic curable resin composition (uncured product) is laminated on the fiber-reinforced resin layer (A) by coating or the like, and cured and bonded by heat or the like to form an integrated structure.

In particular, the method (i) uses a material such as a sheet with an appropriately adjusted degree of curing as the curable resin layer (B), so that it is easy to replace when laminating to a prepreg, etc., it is difficult to melt even when heated, so that the thickness is easy to control, and the material such as a sheet used has elasticity, so that it is easy to follow curved surfaces, etc. In addition, there is also an advantage that the adhesive strength at the interface between the fiber reinforced resin layer (A) and the curable resin layer (B) is higher, especially when bonding by heating.
Furthermore, since the material such as prepreg used in the fiber reinforced resin layer (A) is in a semi-cured state, when it is shaped into an actual product by a molding method such as press molding, it is possible to bond and integrate the prepreg or the like with the elastic curable resin sheet at the same time as shaping, which has the advantage of simplifying the process.

By employing the above-mentioned manufacturing method, for example, the laminate of the present invention can more easily change the layer structure of the fiber-reinforced resin layer (A) and the curable resin layer (B) according to the intended use of the laminate, and the thickness can also be easily adjusted. In addition, it is also easy to manufacture a laminate in which the layer structure of the fiber-reinforced resin layer (A) and the curable resin layer (B) is asymmetric from the center of the laminate to both surfaces in a cross-sectional view of the laminate.

The laminate of the present invention is preferably molded into a desired shape by simultaneously curing the resin components of the fiber-reinforced resin layer (A) and/or the thermosetting resin layer (B) by heating or the like and shaping the laminate with a mold or the like. For example, by subjecting the laminate to known processes such as autoclave molding, hybrid molding, heat and cool press molding, stamping molding, filament winding molding, sheet winding molding, and automated laminate molding by a robot, parts and products for moving objects such as aircraft, automobiles, ships, and railroad cars, as well as sporting goods, home appliances, and building materials can be obtained.

[Fiber-reinforced resin composite lamination member (X)]
In another aspect, the present invention provides a member (X) for use in a laminate of a fiber-reinforced resin composite containing a resin component (a-1) and reinforcing fibers (a-2). The member (X) contains an elastic curable resin (b-1) as a resin component.
The details and preferred embodiments of the resin component (a-1), the reinforcing fiber (a-2), and the elastic curable resin (b-1) are the same as those of the laminate having the fiber reinforced resin layer (A) and the curable resin layer (B), and the description thereof will be omitted.

The member (X) may contain a resin other than the elastic curable resin (b-1), in which case the proportion of the elastic curable resin (b-1) in the member (X) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more.

The shape of the member (X) is not particularly limited, but is preferably a sheet or film from the viewpoints of handling, shaping, secondary processability, etc. The thickness of the sheet or film may be appropriately changed depending on the intended use, but from the viewpoint of impact resistance, it is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, even more preferably 50 μm or more, and preferably 1 mm or less, more preferably 800 μm or less, even more preferably 700 μm or less, even more preferably 650 μm or less, particularly preferably 600 μm or less, and most preferably 550 μm or less.

The tensile elongation of the member (X) is preferably 50% or more, more preferably 100% or more, even more preferably 150% or more, even more preferably 200% or more, and even more preferably 300% or more, in accordance with JIS K 7127:1999, as measured at a test speed of 200 mm/min under an environment of 23°C and 50% RH, and the upper limit is preferably 500%. When the tensile elongation of the member (X) is within the above range, the laminate of the member (X) and the fiber-reinforced resin composite tends to have excellent impact resistance.

From the viewpoint of flexibility, the tensile storage modulus of the member (X) at 100°C and 200°C is preferably 1x10 ⁴ to 6x10 ⁷ Pa, more preferably 6x10 ⁴ to 1x10 ⁷ Pa, and even more preferably 4x10 ⁵ to 9x10 ⁶ Pa. Particularly preferred is a tensile modulus of 1x10 ⁴ to 6x10 ⁷ Pa at 100 to 200°C. Note that "tensile storage modulus of 1x10 ⁴ to 6x10 ⁷ Pa at 100 to 200°C" means that the tensile storage modulus is maintained at a value of 1x10 ⁴ Pa or more and 6x10 ⁷ Pa or less over the entire temperature range of 100 to 200°C.

The glass transition temperature of member (X), measured by a dynamic viscoelasticity measurement method in accordance with JIS K 7244-4:1999, is preferably 100°C or lower, more preferably 80°C or lower, even more preferably 60°C or lower, and even more preferably 40°C or lower, from the viewpoint of obtaining a member with excellent elasticity, and the lower limit is not particularly limited, but is preferably -100°C, more preferably -80°C, and even more preferably -60°C.

The glass transition temperature of member (X) measured by a differential scanning calorimeter in accordance with JIS K 7121:2012 is preferably 90°C or lower, more preferably 70°C or lower, even more preferably 50°C or lower, and even more preferably 30°C or lower, from the viewpoint of obtaining a member with excellent elasticity, and the lower limit is not particularly limited, but is preferably -110°C, more preferably -90°C, and even more preferably -70°C.

The tensile elongation, tensile storage modulus, and glass transition temperature of member (X) measured by dynamic viscoelasticity measurement and differential scanning calorimetry can be measured by the methods described in the examples.

As described above, the member (X) of the present invention is used in a fiber-reinforced resin composite containing the resin component (a-1) and the reinforcing fiber (a-2), preferably in a laminate with a prepreg and/or semipreg. The method for producing a laminate using the member (X) of the present invention includes a step of laminating the prepreg and/or semipreg with the member (X) and a step of curing the prepreg and/or semipreg.

[Resin composition for laminating fiber-reinforced resin composites (Y)]
In yet another aspect, the present invention provides a resin composition (Y) for use in a laminate of a fiber-reinforced resin composite containing a resin component (a-1) and reinforcing fibers (a-2). The fiber-reinforced resin composite is not particularly limited as long as it contains the resin component (a-1) and reinforcing fibers (a-2), and examples thereof include prepregs, semipregs, mixed mats, fiber-reinforced films, fiber-reinforced sheets, and fiber-reinforced boards, although prepregs and/or semipregs are preferred.
The resin composition (Y) contains an epoxy resin having a block structure of a rigid component and a flexible component.
The details and preferred embodiments of the resin component (a-1), the reinforcing fiber (a-2), and the epoxy resin composition are the same as those of the laminate having the fiber-reinforced resin layer (A) and the curable resin layer (B) described above, and the description thereof will be omitted.

The resin composition (Y) of the present invention is used for a fiber-reinforced resin composite, preferably a laminate with a prepreg and/or a semipreg.
The method for producing a laminate using the resin composition (Y) of the present invention includes a step of laminating a fiber-reinforced resin composite and the resin composition (Y) and a step of curing at least the resin composition (Y). When the fiber-reinforced resin composite is a prepreg and/or semipreg, the method includes a step of laminating the prepreg and/or semipreg and the resin composition (Y) and a step of curing the prepreg and/or semipreg and the resin composition (Y).

In addition, the present invention provides a method for producing a laminate using resin composition (Y) in another embodiment, which includes a step of curing a prepreg and/or semipreg, a step of laminating the cured product of the prepreg and/or semipreg with the resin composition (Y), and a step of curing the resin composition (Y).

The lamination method, curing method, etc. in the manufacturing process are the same as those for the laminate having the fiber-reinforced resin layer (A) and the curable resin layer (B) described above, and therefore the description thereof is omitted.

The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples. Note that the various manufacturing conditions and evaluation result values in the following examples are meant as preferred upper or lower limit values in the embodiments of the present invention, and the preferred range may be a range defined by a combination of the above-mentioned upper or lower limit values and the values of the following examples or values between the examples. In the following, all "parts" refer to "parts by mass".

[Various analysis, evaluation and measurement methods]
The methods for analyzing, evaluating and measuring various physical properties and characteristics are as follows:

(1) Tensile elongation A test piece having a width of 15 mm and a length of 150 mm was cut from the curable resin sheet used for the curable resin layer (B) obtained by the method described below. A tensile test was performed on the test piece at a test speed of 200 mm/min in an environment of 23° C. and 50% RH in accordance with JIS K 7127:1999, and the elongation at tensile break was measured.

(2) Tensile storage modulus A test piece was cut out to a width of 10 mm x length of 50 mm from the curable resin sheet used for the curable resin layer (B) obtained by the method described below. According to the dynamic viscoelasticity measurement method described in JIS K 7244-4:1999, a dynamic viscoelasticity measuring device (manufactured by IT Measurement & Control Co., Ltd., "DVA-200") was used to measure the test piece under the measurement conditions of a frequency of 1 Hz, a temperature rise rate of 3 ° C. / min, and a double-support tensile mode, and the storage modulus E' at 50 ° C., 100 ° C., 150 ° C., and 200 ° C. was obtained. In Table 1, "not measurable" means that the test piece broke during the measurement and the tensile storage modulus could not be measured.

(3-1) Glass transition temperature (dynamic viscoelasticity measurement)
In the measurement of (2) above, the peak top temperature of the tensile loss factor (tan δ) calculated from the loss modulus E″ and the storage modulus E′ was taken as the glass transition temperature (Tg).

(3-2) Glass transition temperature (differential scanning calorimetry)
The curable resin sheet used for the curable resin layer (B) obtained by the method described below was measured in accordance with JIS K 7121:2012 using a differential scanning calorimeter Pyris1 DSC (manufactured by PerkinElmer) at a temperature range of -50 to 100 ° C. and a heating rate of 10 ° C./min.

(4) Maximum value of tensile loss factor (tan δ) In the measurement of (2) above, the maximum value of the peak top height of the tensile loss factor (tan δ) calculated from the loss modulus E″ and the storage modulus E′ was regarded as the maximum value of the tensile loss factor (tan δ).

(5) Thickness The thicknesses of the curable resin layer (B), the laminate, and the curable resin layer (B) present in a region at a predetermined thickness from the surface of the laminate were measured by observing the cross section of the laminate with an electron microscope, and the arithmetic average thereof (at any 10 points) was calculated.

(6) Impact resistance The laminate was cut into a size of 50 mm wide x 50 mm long to prepare a test piece, and the test was performed by setting the test piece between a striking die (radius 6.5 mm, tip ¼ inch type) and a receiving stand (for ¼ inch type) of a DuPont impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) with reference to JIS K 5600-5-3:1999, and dropping a weight on the test piece. In order to clarify the effect of improving impact resistance by the curable resin layer (B), the tests were performed under the following conditions for each of the examples and comparative examples, and the degree of damage to the test piece after the test was evaluated according to the following criteria.

(Examples 1 and 2 and Comparative Examples 1 and 2)
[1]
Test conditions: Weight 1 kg, weight height 30 cm
Evaluation criteria: "A" indicates that there is no scattering of material but that the reinforcing fibers are broken.
The weight penetrates in the thickness direction and the material is scattered, which is called "C".
[2]
Test conditions: Weight 300g, weight height 20cm
Evaluation criteria: "A" indicates that there is breakage of the reinforcing fiber on the receiving surface.
Those with breaks in the reinforcing fibers on both the receiving surface and the back surface are rated "C".

(Examples 3 and 4 and Comparative Examples 3 and 4)
[1]
Test conditions: Weight 1 kg, weight height 30 cm
Evaluation criteria: "A" if there are only dents on the receiving surface
Those with no breakage of the reinforcing fibers on the receiving surface but cracks in the resin layer are rated as "B".
The weight penetrates in the thickness direction and the material is scattered, which is called "C".
[2]
Test conditions: Weight 300g, weight height 20cm
Evaluation criteria: "A" indicates that there is only a dent on the receiving surface and no breakage of the reinforcing fibers on either the receiving surface or the back surface.
The receiving surface has only dents, but the resin layer on the back side has cracks, so it is rated as "B".
Those with cracks in the resin layer on both the receiving surface and the back surface are rated "C".

(7) Vibration Damping The laminate was cut into a 20 cm square to prepare a test specimen, which was then fixed to a jig in a free support state (a hole of 5 mm diameter was drilled at one of the four corners and the specimen was hung with a silicone string). An acceleration sensor "PCB Piezotronics Model: 352A26" manufactured by PCB Piezotronics was attached to the center of one side of the test specimen using petrowax, and the specimen was vibrated from the other side with an impulse hammer "PCB Piezotronics Model: 086C03" manufactured by PCB Piezotronics. The force applied to the test specimen was detected by the impulse hammer, and at the same time, the acceleration applied to the test specimen was detected by the acceleration sensor. The inertance (acceleration/force) was calculated, and a graph of inertance-time was created. The time (ms) until the inertance became 5 (m/s ² )/N or less was obtained, and the vibration damping was evaluated according to the following criteria.
A: Time is less than 350 ms (vibration control effect)
B: Time 350 ms or more (no vibration damping effect)

(8) Interlayer Adhesion A test piece having a width of 15 mm and a length of 150 mm was cut out from the laminate having the substrate, and a 180° peel test was performed at the interface between the fiber reinforced resin layer (A) and the curable resin layer (B) at a test speed of 50 mm/min using a universal material testing machine ("AGS-X" manufactured by Shimadzu Corporation). The peel mode was observed and evaluated according to the following criteria.
A: The fiber reinforced resin layer (A) and the curable resin layer (B) did not peel off, and the substrate on the handle side broke. B: Cohesive failure occurred in layer (B). C: The interface between the fiber reinforced resin layer (A) and layer (B) was broken.

The curable resin sheets and laminates used in the curable resin layer (B) in the examples and comparative examples were prepared as follows, and the above-mentioned analyses, evaluations, and measurements were carried out. The results are shown in Tables 1 and 2. The prepreg used in the fiber-reinforced resin layer (A) was "TR3110 381GMX" (thickness: 210-220 μm, base material: epoxy resin) manufactured by Mitsubishi Chemical Corporation.

Example 1
(Preparation of base epoxy resin (α) of curable resin sheet)
In a 1 L glass flask equipped with a stirrer, a dropping funnel and a thermometer, 141.8 parts by mass of 1,6-hexanediol preheated to 45°C and 0.51 parts by mass of boron trifluoride ethyl ether were charged and heated to 80°C. 244.3 parts by mass of epichlorohydrin were dropped over a period of time so that the temperature did not exceed 85°C. After aging for 1 hour while maintaining the temperature at 80 to 85°C, the mixture was cooled to 45°C. 528.0 parts by mass of a 22% by mass aqueous sodium hydroxide solution was added thereto and vigorously stirred at 45°C for 4 hours. The mixture was cooled to room temperature to separate and remove the aqueous phase, and heated under reduced pressure to remove unreacted epichlorohydrin and water, to obtain 283.6 parts by mass of crude 1,6-hexanediol diglycidyl ether.
This crude 1,6-hexanediol diglycidyl ether was distilled and purified in an Oldershaw distillation column (15 plates) and the fraction at a pressure of 1300 Pa and 170 to 190°C was taken as the main fraction, thereby obtaining 127.6 parts by mass of 1,6-hexanediol diglycidyl ether having a diglycidyl form purity of 97% by mass as determined by a gas chromatography method, a total chlorine content of 0.15% by mass, and an epoxy equivalent of 116 g/eq.
100 parts by mass of the 1,6-hexanediol diglycidyl ether, 69.3 parts by mass of bisphenol F (phenolic hydroxyl group equivalent: 100 g/eq), and 0.13 parts by mass of ethyltriphenylphosphonium iodide (30% by mass solution in methyl cellosolve) were placed in a pressure-resistant reaction vessel and subjected to a polymerization reaction at 165 to 170° C. for 5 hours under a nitrogen gas atmosphere, thereby obtaining a copolymer of bisphenol F and 1,6-hexanediol glycidyl ether having an epoxy equivalent of 1,000 g/eq and a number average molecular weight of 3,000.
(Preparation of curable resin sheet)
A curable resin composition was prepared by blending 8.5 parts by mass of a curing agent ("jER Cure ST-14" manufactured by Mitsubishi Chemical Corporation) with 100 parts by mass of the above epoxy resin (α). The composition was sandwiched between separator films ("Diafoil MRF-75" manufactured by Mitsubishi Chemical Corporation, a polyethylene terephthalate film with one side silicone coated, thickness 75 μm), adjusted to a desired thickness, subjected to a primary heat treatment at 40° C. for 16 hours, and further subjected to a secondary heat treatment at 80° C. for 6 hours, to obtain a curable resin sheet with a thickness of 200 μm.
(Preparation of Laminate)
As a material used for the fiber reinforced resin layer (A), the separator film of the prepreg "TR3110 381GMX" manufactured by Mitsubishi Chemical Corporation was peeled off and laminated on both sides of the curable resin sheet. Then, a pressure of 0.8 MPa was applied with a heat press machine, and the laminate was heat pressed at 130 ° C. for 90 minutes to obtain a laminate having a thickness of 630 μm.

Example 2
A laminate having a thickness of 910 μm was produced in the same manner as in Example 1, except that the thickness of the curable resin sheet was 500 μm.

Example 3
Two curable resin sheets with a thickness of 125 μm were prepared in the same manner as in Example 1. Then, prepregs from which the separator films had been peeled off were laminated on both sides of each of the two curable resin sheets in the same manner as in Example 1. Four layers of prepregs from which the separator films had been peeled off were further laminated between the two curable resin sheets with prepregs laminated on both sides. Then, a pressure of 0.8 MPa was applied with a heat press machine, and the laminate was heat-pressed at 130° C. for 90 minutes to obtain a laminate with a thickness of 1910 μm.

Example 4
Two curable resin sheets having a thickness of 125 μm were prepared in the same manner as in Example 1. Then, two layers of prepreg ("TR3110 381GMX" manufactured by Mitsubishi Chemical Corporation) from which the separator film had been peeled off were laminated on both sides of each of the two curable resin sheets. Then, two curable resin sheets each having two layers of prepreg laminated on both sides were laminated. Then, a pressure of 0.8 MPa was applied with a heat press machine, and the sheets were heat-pressed at 130° C. for 90 minutes to obtain a laminate having a thickness of 1910 μm.

Example 5
A curable resin sheet having a thickness of 125 μm was produced in the same manner as in Example 1. Three layers of prepreg ("TR3110 381GMX" manufactured by Mitsubishi Chemical Corporation) from which the separator film had been peeled off were laminated on one side of the curable resin sheet, and a substrate (polyethylene terephthalate film, "Diafoil T100" manufactured by Mitsubishi Chemical Corporation) was laminated on the other side of the curable resin sheet, and a pressure of 0.8 MPa was applied with a heat press machine, followed by heat pressing at 130° C. for 90 minutes to obtain a laminate for interlayer adhesion test.

<Comparative Example 1>
The separator films of two Mitsubishi Chemical Corporation "TR3110 381GMX" prepregs were peeled off, and two layers were laminated together. A pressure of 0.8 MPa was applied using a heat press machine, and the laminate was heat pressed at 130°C for 90 minutes to obtain a laminate having a thickness of 440 µm.

<Comparative Example 2>
A laminate having a thickness of 630 μm was obtained in the same manner as in Example 1, except that a curable resin sheet prepared as follows was used.
A resin composition was prepared by blending 50 parts by mass of a curing agent ("jER Cure ST14" manufactured by Mitsubishi Chemical Corporation) with 100 parts by mass of an epoxy resin ("jER828" manufactured by Mitsubishi Chemical Corporation). The composition was sandwiched between separator films, adjusted to a desired thickness, and subjected to a primary heat treatment at 40°C for 16 hours, and then a secondary heat treatment at 80°C for 6 hours to obtain a curable resin sheet having a thickness of 200 μm.

<Comparative Example 3>
A laminate having a thickness of 1650 μm was obtained in the same manner as in Comparative Example 1, except that the separator films of eight prepregs of “TR3110 381GMX” manufactured by Mitsubishi Chemical Corporation were peeled off and eight layers were laminated.

<Comparative Example 4>
A laminate having a thickness of 1,900 μm was obtained in the same manner as in Example 3, except that the two curable resin sheets were replaced with inorganic filler-containing polyester sheets ("Neofade 4140" manufactured by Koyo Sangyo Co., Ltd., thickness 125 μm).

<Comparative Example 5>
A laminate for interlayer adhesion test was obtained in the same manner as in Example 5, except that the curable resin sheet was an inorganic filler-containing polyester sheet ("Neofade 4140" manufactured by Koyo Sangyo Co., Ltd., thickness 125 μm).

The laminates of Examples 1 to 4 are found to have excellent impact resistance and heat resistance, as well as excellent vibration damping properties. In addition, the evaluation results of the interlayer adhesion of the laminate of Example 5 show that the laminate of the present invention also has excellent interlayer adhesion.

The laminate of the present invention has excellent impact resistance and heat resistance, as well as excellent vibration damping and interlayer adhesion, and is therefore suitable for use in aircraft, automobiles, ships, railroad cars, and other moving objects, sporting goods, home appliances, and building materials.

Claims (14)

A fiber-reinforced resin layer (A) containing a resin component (a-1) and a reinforcing fiber (a-2), and a curable resin layer (B) containing an elastic curable resin (b-1) ,
The curable resin layer (B) has a tensile storage modulus of 1×10 ⁴ to 6×10 ⁷ Pa at 100° C. and 200° C. A fiber-reinforced resin layer (A) containing a resin component (a-1) and a reinforcing fiber (a-2), and a curable resin layer (B) containing an elastic curable resin (b-1) ,
A laminate , wherein the raw material of the elastic curable resin (b-1) constituting the curable resin layer (B) has a tensile storage modulus of 1×10 ⁴ to 6×10 ⁷ Pa at 100° C. and 200° C. A fiber-reinforced resin layer (A) containing a resin component (a-1) and a reinforcing fiber (a-2), and a curable resin layer (B) containing an elastic curable resin (b-1) ,
The curable resin layer (B) is a cured product obtained by curing an epoxy resin composition containing an epoxy resin and a curing agent having a polyetheramine and/or an alicyclic structure . A fiber-reinforced resin layer (A) containing a resin component (a-1) and a reinforcing fiber (a-2), and a curable resin layer (B) containing an elastic curable resin (b-1) ,
The curable resin layer (B) is a cured product obtained by curing an epoxy resin composition containing an epoxy resin and an alicyclic polyamine . A fiber-reinforced resin layer (A) containing a resin component (a-1) and a reinforcing fiber (a-2), and a curable resin layer (B) containing an elastic curable resin (b-1) ,
The elastic curable resin (b-1) is an epoxy resin, and the epoxy resin has a block structure of a rigid component and a flexible component . The laminate according to any one of claims 1 to 5, wherein the curable resin layer (B) has a tensile elongation of 50% or more. The laminate according to any one of claims 1 to 6 , wherein the tensile elongation of the elastic curable resin (b-1) raw material constituting the curable resin layer (B) is 50% or more. The laminate according to any one of claims 1 to 7 , wherein the thickness of the curable resin layer (B) is 10 µm or more and 1 mm or less. The laminate according to any one of claims 1 to 8 , wherein the thickness ratio of the curable resin layer (B) in the laminate is 5% or more and 70% or less. The laminate according to any one of claims 1 to 9 , wherein the curable resin layer (B) is present in an area within 40% of the thickness of the laminate from the surface of the laminate. The laminate according to any one of claims 1 to 10 , wherein the thickness of the curable resin layer (B) present in a region within 1 mm from the surface of the laminate is 10 µm or more and 800 µm or less. The laminate according to any one of claims 1 to 11 , wherein the resin component (a-1) is an epoxy resin. The laminate according to any one of claims 1 to 12 , wherein the fiber reinforced resin layer (A) is a cured product obtained by curing a prepreg . A mobile object such as an aircraft, an automobile, a ship or a railroad car, a sporting good, a home electric appliance or a building material, comprising the laminate according to any one of claims 1 to 13 .