Multilayer structure and manufacturing method therefor, automobile component, aircraft component, and carbon

Abstract

Provided is a multilayer structure having excellent vibration resistance, wherein the following multilayer structure is provided. A multilayer structure having an ethylene-vinyl alcohol copolymer layer (A) and a carbon fiber-reinforced plastic layer (B), the ethylene-vinyl alcohol copolymer having a glass transition temperature (Tg) of 0-60 DEG C.

Description

Technical Field

[0001] The present invention relates to a multilayer structure and a method for producing the same, an automobile component, an aircraft component, and a vibration-proof material for carbon fiber reinforced plastic. Background Art

[0002] Carbon fiber reinforced plastic (hereinafter sometimes referred to as "CFRP") is a composite material including a carbon fiber reinforcement material and a resin, and is widely used in parts of aircraft, automobiles, ships and other various transportation equipment, sporting goods, recreational goods, etc. (see, for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-091178 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] CFRP is lighter and more rigid than metals such as aluminum and iron, and has therefore attracted much attention in recent years as a new raw material to replace metals. However, due to its high rigidity, a problem is that CFRP makes a metallic sound when struck. Therefore, for applications such as automobile ceilings, improved vibration resistance is required.

[0008] Solutions for solving problems

[0009] The present inventors have conducted intensive studies in view of this situation and have found that a multilayer structure having excellent vibration resistance can be obtained by providing a layer containing a specific ethylene-vinyl alcohol copolymer in a multilayer structure having a carbon fiber reinforced plastic layer.

[0010] That is, the present invention provides the following [1] to

[12] .

[0011] [1] A multilayer structure comprising an ethylene-vinyl alcohol copolymer layer (A) and a carbon fiber reinforced plastic layer (B), wherein the ethylene-vinyl alcohol copolymer has a glass transition temperature (Tg) of 0 to 60°C.

[0012] [2] The multilayer structure according to [1], wherein the ethylene-vinyl alcohol copolymer has a glass transition temperature (Tg) of 0 to 45°C.

[0013] [3] The multilayer structure according to [1] or [2], wherein the ethylene-vinyl alcohol copolymer has a glass transition temperature (Tg) of 0 to 30°C.

[0014] [4] The multilayer structure according to any one of [1] to [3], wherein the ethylene-vinyl alcohol copolymer is a modified ethylene-vinyl alcohol copolymer having a structural unit represented by the following chemical formula (1).

[0015]

[0016] (In the chemical formula (1), X represents an organic chain having a heteroatom, and n represents a positive integer.)

[0017] [5] The multilayer structure according to [4], wherein in the chemical formula (1), the heteroatom in X is an oxygen atom, a nitrogen atom or a sulfur atom.

[0018] [6] The multilayer structure according to [4] or [5], wherein in the chemical formula (1), n ​​is 1 to 20.

[0019] [7] The multilayer structure according to any one of [1] to [6], wherein the ethylene-vinyl alcohol copolymer layer (A) is laminated on at least one surface of the carbon fiber reinforced plastic layer (B).

[0020] [8] The multilayer structure according to any one of [1] to [7], which is used for automobile parts or aircraft parts.

[0021] [9] A method for producing a multilayer structure, comprising: laminating an ethylene-vinyl alcohol copolymer layer (A) on at least one surface of a carbon fiber reinforced plastic layer (B).

[0022]

[10] An automobile part comprising the multilayer structure according to any one of [1] to [7].

[0023]

[11] An aircraft component comprising the multilayer structure according to any one of [1] to [7].

[0024]

[12] A vibration-proof material for carbon fiber reinforced plastics, comprising an ethylene-vinyl alcohol copolymer layer, wherein the ethylene-vinyl alcohol copolymer has a glass transition temperature (Tg) of 0 to 60°C.

[0025] Effects of the Invention

[0026] The multilayer structure of the present invention is excellent in vibration resistance. DETAILED DESCRIPTION

[0027] Hereinafter, the present invention will be described in detail, but this is just an example of a preferred embodiment.

[0028] It should be noted that, in the present invention, when expressed as "X to Y" (X, Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less" and the meaning of "preferably greater than X" or "preferably less than Y".

[0029] In the present invention, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), it also includes the meaning of "preferably greater than X" or "preferably less than Y".

[0030] In the present invention, "x and / or y (x, y are arbitrary structures or components)" means only x, only y, or a combination of x and y.

[0031] In the present invention, "(meth)acrylic" means acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate.

[0032] In the present invention, the term "film" also includes "tape" and "sheet".

[0033] A multilayer structure as one embodiment of the present invention (hereinafter sometimes referred to as "the present multilayer structure") includes an ethylene-vinyl alcohol copolymer layer (hereinafter sometimes referred to as "EVOH layer") (A) and a carbon fiber reinforced plastic layer (hereinafter sometimes referred to as "CFRP layer") (B).

[0034] Hereinafter, each configuration will be described.

[0035] [EVOH layer (A)]

[0036] The EVOH layer (A) contains an ethylene-vinyl alcohol copolymer (hereinafter sometimes referred to as "EVOH"). That is, the content of EVOH in the EVOH layer (A) is not particularly limited, and EVOH is preferably the main component (50% by mass or more). The content of EVOH is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, and can be 95% by mass or more, or 100% by mass.

[0037] EVOH is a resin obtained by saponifying a copolymer of ethylene and a vinyl ester monomer, that is, an ethylene-vinyl ester copolymer, and is a water-insoluble thermoplastic resin. As the vinyl ester monomer, vinyl acetate is generally used from an economical point of view.

[0038] As a copolymerization method of ethylene and vinyl ester monomers, any known polymerization method, such as solution polymerization, suspension polymerization, emulsion polymerization, etc., can be used. Usually, solution polymerization using methanol as a solvent is used. The saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by a known method.

[0039] The EVOH produced in this manner mainly contains ethylene structural units and vinyl alcohol structural units, and contains a certain amount of vinyl ester structural units remaining as unsaponified portions when the saponification degree is less than 100 mol %.

[0040] As the vinyl ester monomer, vinyl acetate is generally used as described above from the economic point of view and the efficiency of treating impurities during production. In addition, as the vinyl ester monomer other than vinyl acetate, for example, aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate; aromatic vinyl esters such as vinyl benzoate, etc. can be listed. These can be used alone or in combination of two or more. Among them, aliphatic vinyl esters having 3 to 20 carbon atoms are preferred, more preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms are preferred.

[0041] The content of ethylene structural units measured according to ISO14663 of EVOH is usually 20 to 60 mol%, preferably 25 to 55 mol%, and particularly preferably 27 to 55 mol%. By making the content within the above range, the adhesion to CFRP can be further improved. It should be noted that the content of the ethylene structural unit can be controlled by the ethylene pressure when the vinyl ester monomer and ethylene are copolymerized.

[0042] The saponification degree measured according to JIS K6726 of EVOH (a solution obtained by uniformly dissolving EVOH in a water / methanol solvent) is usually 90 to 100 mol%, preferably 92 to 100 mol%, and particularly preferably 94 to 100 mol%. When the saponification degree is too low, there is a tendency for thermal stability, moisture resistance, etc. to decrease. It should be noted that the saponification degree can be controlled by the amount of the saponification catalyst (usually a basic catalyst such as sodium hydroxide is used) when saponifying the ethylene-vinyl ester copolymer, the temperature, the time, etc.

[0043] The glass transition temperature (Tg) of EVOH is usually 0 to 60° C., preferably 0 to 45° C., and particularly preferably 0 to 35° C. If the glass transition temperature is too low, blocking of the molded product tends to occur. The glass transition temperature can be measured using a differential scanning calorimeter.

[0044] Specifically, the glass transition temperature of EVOH can be calculated by measuring using a differential scanning calorimeter under the following conditions.

[0045] (a) Conditioning of the test piece: After melting at 230°C for 1 minute, the sample was cooled to -30°C at a cooling rate of 10°C / min.

[0046] (b) Analysis of glass transition temperature: The sample cooled in (a) was heated to 230° C. at a heating rate of 10° C. / min.

[0047] (c) Calculation of glass transition temperature: Based on the DSC curve obtained in (b), the midpoint temperature of the step-like change portion of the glass transition was calculated as the glass transition temperature.

[0048] The melt flow rate (MFR) of EVOH (210°C, load 2160g) is usually 0.1 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, and particularly preferably 3 to 35 g / 10 minutes. If the MFR is too large, the film forming properties tend to become unstable, while if it is too small, the viscosity tends to become too high, making it difficult to melt extrude.

[0049] This MFR serves as an index of the degree of polymerization of EVOH, and can be adjusted by the amount of the polymerization initiator and the amount of the solvent when ethylene and the vinyl ester monomer are copolymerized.

[0050] EVOH may further contain a structural unit derived from the following comonomer within a range not inhibiting the effects of the present invention (for example, 10 mol % or less of EVOH).

[0051] Examples of the comonomer include olefins such as propylene, 1-butene, and isobutylene; α-olefins containing a hydroxyl group such as 3-butene-1-ol, 3-butene-1,2-diol, 4-pentene-1-ol, and 5-hexene-1,2-diol, or their esters, acylates, and other derivatives; hydroxyalkyl vinylides such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, phthalic acid (anhydride), maleic acid (anhydride), itaconic acid (anhydride) or their salts, or monoalkyl esters or dialkyl esters having 1 to 18 carbon atoms in the alkyl group; acrylamide, N-alkyl acrylamide having 1 to 18 carbon atoms in the alkyl group, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salts, acrylamidopropyl dimethyl acrylamides such as methyl methacrylamide, N-alkyl methacrylamide with an alkyl group having 1 to 18 carbon atoms, N,N-dimethyl methacrylamide, 2-methyl acrylamide propanesulfonic acid or its salt, methyl acrylamide propyl dimethylamine or its acid salt or its quaternary salt; N-vinyl amides such as N-vinyl pyrrolidone, N-vinyl formamide, N-vinyl acetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; Vinyl ethers such as 1 to 18 alkyl vinyl ethers, hydroxyalkyl vinyl ethers, and alkoxyalkyl vinyl ethers; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; allyl halogen compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; comonomers such as trimethyl-(3-acrylamide-3-dimethylpropyl)ammonium chloride and acrylamide-2-methylpropanesulfonic acid. These may be used alone or in combination of two or more.

[0052] In particular, from the viewpoint of maintaining gas barrier properties and good secondary moldability, EVOH copolymerized with α-olefins containing hydroxyl groups, that is, EVOH having hydroxyl groups in the side chains is preferred, EVOH having primary hydroxyl groups in the side chains is more preferred, and EVOH having a 1,2-diol structure in the side chains is particularly preferred.

[0053] In EVOH having a primary hydroxyl group in a side chain, the content of the structural unit derived from a monomer having the primary hydroxyl group is usually preferably 0.1 to 20 mol %, more preferably 0.5 to 15 mol %, particularly preferably 1 to 10 mol % of the EVOH.

[0054] EVOH may be subjected to "post-modification" such as urethanization, acetalization, cyanoethylation, or oxyalkyleneization.

[0055] Furthermore, the EVOH may be two or more types of EVOH, for example, a mixture of EVOHs having different saponification degrees, different polymerization degrees, different copolymerization components, and the like.

[0056] The EVOH layer (A) may include a modified EVOH having a structural unit represented by the following chemical formula (1), which is preferably present in the main chain of EVOH.

[0057]

[0058] (In the chemical formula (1), X represents an organic chain having a heteroatom, and n represents a positive integer.)

[0059] In the above chemical formula (1), X represents an organic chain having a heteroatom. Examples of the heteroatom include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, etc. Among these, from an industrial point of view, the heteroatom is preferably an oxygen atom, a nitrogen atom or a sulfur atom, and particularly preferably an oxygen atom.

[0060] In addition, from the viewpoint of production, X is preferably an organic chain having a "hydrocarbon chain optionally having a substituent" starting from a carbonyl group and having a "heteroatom optionally having a substituent at the end of the repeating unit". In addition, X may have other heteroatoms as long as it has a carbonyl group as a starting point and has a heteroatom at least at the end of the repeating unit.

[0061] The above X is an organic chain having a "hydrocarbon chain optionally having a substituent" and a "heteroatom optionally having a substituent at a terminal of a repeating unit", and the "hydrocarbon chain optionally having a substituent" is defined as R x , when "a heteroatom which may have a substituent at a terminal of the repeating unit" is defined as Z, it is represented as in the following chemical formula (2).

[0062]

[0063] (In chemical formula (2), R x represents a hydrocarbon chain optionally having a substituent, Z represents a heteroatom optionally having a substituent, and n represents a positive integer. )

[0064] In the chemical formula (2), when Z is an oxygen atom, examples of the repeating unit include -CO-R x When -O- and Z is a nitrogen atom, examples of the repeating unit include -CO-R x -NH-, -CO-R x -NR 3 -, when Z is a sulfur atom, examples of the repeating unit include -CO-R x -S-.

[0065] It should be noted that examples of the substituents that the hydrocarbon and heteroatom may have include alkyl groups such as methyl and ethyl, aryl groups such as aromatic rings, and acyl groups such as acetyl. x -NR 3 -R in 3 It represents an alkyl group such as a methyl group and an ethyl group, an aryl group such as an aromatic ring, and an acyl group such as an acetyl group.

[0066] Among these, from the viewpoint of improving the gas barrier properties, the repeating unit is preferably -CO-R x -O-, -CO-R x -NH- or CO-R x -S-, Z is particularly preferably an oxygen atom. Specifically, it is preferred that the aliphatic polyester unit represented by the following chemical formula (3) be included.

[0067]

[0068] (In chemical formula (3), R x represents a hydrocarbon chain optionally having a substituent, and n represents a positive integer. )

[0069] The hydrocarbon chain R in the chemical formulas (2) and (3) is x The straight chain or branched chain having 1 to 10 carbon atoms is preferably a straight chain or branched chain. Examples of the straight chain or branched chain hydrocarbon chain having 1 to 10 carbon atoms include a methylene group (-CH2-), a methine group (-CHR-), a quaternary carbon group having no hydrogen atom (-CR 1 R 2 -), propylene, isopropylene, butylene, isobutylene, phenylene, etc. The R, R 1 , R 2 represents an alkyl group such as a methyl group or an ethyl group, or an aromatic group such as an aromatic ring. Among them, as a hydrocarbon chain, a linear or branched alkyl chain having 2 to 8 carbon atoms is more preferred, and a linear or branched alkyl chain having 3 to 7 carbon atoms is further preferred. Among these, from the viewpoint of improving the storage stability and processing stability of the resin, a linear hydrocarbon chain is preferred, a linear alkyl chain having 2 to 8 carbon atoms is further preferred, and a linear alkyl chain having 3 to 7 carbon atoms is particularly preferred.

[0070] In the chemical formulae (1) to (3), n represents a positive integer. n is preferably an integer of 1 to 20, and more preferably an integer of 1 to 10. If n is too large, the barrier properties tend to decrease, and therefore, n is preferably an integer of 20 or less.

[0071] It should be noted that in the chemical formula (1), when n is 2 or more, a plurality of Xs may be the same or different, but are preferably the same from the viewpoint of barrier properties. xand Z may be the same or different, but are preferably the same from the viewpoint of barrier properties. x They may be the same or different, but are preferably the same from the viewpoint of barrier properties.

[0072] The average value of n in the above chemical formulas (1) to (3) in the modified EVOH (that is, sometimes referred to as "average chain length of the graft chain") is preferably in the range of 1 to 10, more preferably in the range of 1 to 5, further preferably in the range of 1 to 2, and particularly preferably in the range of 1 to 1.5. If the average value of n is too large, the variation in the chain length of the graft chain becomes large, and thus there is a tendency for the gas barrier properties to decrease, so it is preferably 10 or less.

[0073] The structural units represented by chemical formulae (1) to (3) can be identified by general organic chemical methods such as nuclear magnetic resonance spectroscopy (NMR), infrared spectrophotometry, and mass spectrometry.

[0074] The average chain length of the grafted chains in the chemical formulas (1) to (3) in the modified EVOH can be calculated according to 1 The calculation was performed based on the results of H-NMR measurement.

[0075] [Method for producing modified EVOH]

[0076] The modified EVOH having the structural unit represented by the chemical formula (1) in the main chain can be obtained as follows: for example, a compound having EVOH and a heterofunctional group is heated and stirred in a molten state of EVOH in a stirring tank type manufacturing device having stirring blades, or a grafting reaction is carried out using an extruder, a shear molding processing machine with a return screw, etc.

[0077] The formation of the repeating unit having the chemical formula (1) in the main chain of the modified EVOH, that is, the side chain graft structure by the graft reaction, starts with the hydroxyl group of EVOH as the terminal.

[0078] [Compounds having heterofunctional groups]

[0079] The heterofunctional group refers to a functional group having a heteroatom, and as the heteroatom, oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, etc. can be listed, among which oxygen atoms, nitrogen atoms, and sulfur atoms are preferred. As the functional group having a heteroatom (heterofunctional group), specifically, ester groups, carboxylic acid groups, acyl groups, thioester groups, amide groups, carbonate groups, carbamate groups, thiocarbamate groups, urea groups, N-acyl groups, N,N'-diacyl groups, etc. can be listed.

[0080] As the compound with heterofunctional groups, cyclic compounds, carboxylic acid compounds, carbonate compounds, carbamate compounds, thiocarbamate compounds, diacyl compounds, triacyl compounds and their analogues etc. with heterofunctional groups can be listed. They can be used alone or in combination of two or more. Among them, preferably cyclic compounds with heterofunctional groups.

[0081] [Cyclic compounds with heterofunctional groups]

[0082] The cyclic compound having a heterofunctional group is preferably a heterocyclic compound having 2 or more carbon atoms. Examples of the cyclic compound having a heterofunctional group include cyclic esters such as lactones; cyclic amides such as lactams; cyclic carbonates such as ethylene carbonate and propylene carbonate; cyclic thioesters such as epitane-2-one, 3,3-dimethyl epitane-2-one, 4-methyl epitane-2-one, 3-methyl epitane-2-one, 3-ethyl epitane-2-one, and 3-methyl-3-ethyl epitane-2-one; cyclic carbamates such as ethylene carbamate; imide compounds such as phenylphthalimide and cyclohexanedicarboximide; cyclic urea derivatives such as N,N'-dimethylpropyleneurea and 1,3-dimethyl-2-imidazolidinone; cyclic N,N'-diacyl compounds such as N-acyl-substituted caprolactam, etc. Among these, cyclic esters are preferred, and lactones are more preferred.

[0083] As the modified EVOH, aliphatic polyester-modified EVOH is particularly preferably used. Aliphatic polyester-modified EVOH is EVOH containing aliphatic polyester units.

[0084] A method for obtaining aliphatic polyester-modified EVOH will be described.

[0085] Methods for obtaining aliphatic polyester-modified EVOH include: (1) a method of ring-opening polymerization of lactones in the presence of EVOH; (2) a method of ring-opening polymerization and polycondensation of aliphatic polyesters and lactones to obtain a polyester having a carboxyl group at the terminal, and then reacting the polyester having a carboxyl group at the terminal with EVOH.

[0086] Among them, the method of ring-opening polymerization of lactones in the presence of EVOH can easily obtain a resin in which EVOH is grafted with an aliphatic polyester through a one-stage reaction. Therefore, it is less labor-intensive and simpler than the method of generating an aliphatic polyester through ring-opening polymerization and a condensation reaction in advance and then reacting it with EVOH, and is preferred.

[0087] As the lactone, preferably, a lactone which forms an aliphatic polyester by ring-opening polymerization and has a carbon number of 3 to 10 in the constituting ring is used. When such a lactone has no substituent, it is represented by the following chemical formula (4).

[0088]

[0089] In the chemical formula (4), n is an integer of 2 to 9, and n is preferably 4 to 5. In addition, the alkylene chain -(CH2) in the chemical formula (4) n Any carbon atom in - may have at least one substituent such as a lower alkyl group or lower alkoxy group having about 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, or an aralkyl group.

[0090] Specific examples of such lactones include β-propiolactones, γ-butyrolactones, ε-caprolactones, and δ-valerolactones.

[0091] Examples of the β-propiolactones include β-propiolactone and dimethylpropiolactone.

[0092] Examples of the γ-butyrolactones include butyrolactone, γ-valerolactone, γ-caprolactone, γ-octalactone, γ-laurolactone, γ-palmitolactone, γ-stearolactone, crotonolactone, α-angelica lactone, and β-angelica lactone.

[0093] Examples of the ε-caprolactones include monoalkyl-ε-caprolactone such as ε-caprolactone, monomethyl-ε-caprolactone, monoethyl-ε-caprolactone, monodecyl-ε-caprolactone, monopropyl-ε-caprolactone, and monodecyl-ε-caprolactone; dialkyl-ε-caprolactones in which carbon atoms other than the ε position are substituted with two alkyl groups; trialkyl-ε-caprolactones in which carbon atoms other than the ε position are substituted with three alkyl groups; alkoxy-ε-caprolactones such as ethoxy-ε-caprolactone; cycloalkyl-lactones such as cyclohexyl-ε-caprolactone; aralkyl-ε-caprolactones such as benzyl-ε-caprolactone; and aryl-ε-caprolactones such as phenyl-ε-caprolactone.

[0094] Examples of the δ-valerolactones include 5-valerolactone, 3-methyl-5-valerolactone, 3,3-dimethyl-5-valerolactone, 2-methyl-5-valerolactone, and 3-ethyl-5-valerolactone.

[0095] These lactones can be used alone or in combination of two or more.

[0096] Among these, ε-caprolactones and δ-valerolactones are particularly preferred, and ε-caprolactone is particularly preferred from the viewpoint of being inexpensive and easily available.

[0097] [Carboxylic acid compound]

[0098] Examples of the carboxylic acid compound include linear carboxylic acid esters, linear carboxylic acid thioesters, linear carboxylic acid amides, carboxylic acid halides or anhydrides, etc. Among these, linear carboxylic acid esters are preferred.

[0099] [Carbonate compounds]

[0100] Examples of the carbonate compound include various dialkyl carbonates, diaryl carbonates, and aryl alkyl carbonates.

[0101] [Carbamate compound]

[0102] Examples of the carbamate compound include methyl carbamate and ethyl carbamate.

[0103] [Thiocarbamate compounds]

[0104] Examples of the thiocarbamate compound include derivatives such as dimethylamino-S-aryl thiocarbamate.

[0105] [Diacyl compounds]

[0106] Examples of the diacyl compound include diethylamide and diacetyl(cyclopentyl)azane.

[0107] [Triacyl compounds]

[0108] Examples of the triacyl compound include triacetamide and tribenzamide.

[0109] In addition, as a compound having a heterofunctional group, an oligomer or polymer of a repeating structural unit represented by n in chemical formulas (1) to (3) can also be used. For example, polyesters such as poly-ε-caprolactone and polylactic acid; polyamides such as poly-ε-caprolactam; or polythioesters can be used.

[0110] As described above, the modified EVOH having the structural unit represented by the chemical formula (1) can be manufactured as follows: EVOH and a compound having a heterofunctional group are heated and stirred in a stirring tank type manufacturing device having stirring blades in a molten state of EVOH, or a grafting reaction is carried out using an extruder, a shear molding machine with a return screw, etc.

[0111] For example, when a cyclic compound having a heterofunctional group is used as the compound having a heterofunctional group, a modified EVOH having a structural unit represented by the chemical formula (1) in the main chain can be produced by performing a ring-opening polymerization reaction and a grafting reaction of the cyclic compound having a heterofunctional group in the presence of EVOH. On the other hand, when a carboxylic acid compound is used as the compound having a heterofunctional group, a modified EVOH having a structural unit represented by the chemical formula (1) in the main chain can be produced by performing a nucleophilic substitution reaction or a dehydration condensation reaction and a grafting reaction of the carboxylic acid compound in the presence of EVOH.

[0112] Among them, the modified EVOH is preferably a ring-opening polymer of a lactone ring having 3 to 10 carbon atoms constituting the ring.

[0113] In the case of a reaction accompanied by ring-opening polymerization, it is preferred to add a known ring-opening polymerization catalyst. As a ring-opening polymerization catalyst, for example, titanium compounds, tin compounds, etc. can be listed. Specifically, titanium alkoxides such as titanium tetra-n-butoxide, titanium tetraisobutoxide, and titanium tetraisopropoxide; tin alkoxides such as dibutyl dibutoxy tin; tin ester compounds such as 2-ethylhexanoate and dibutyltin diacetate, etc. can be listed. They can be used alone or in combination of two or more. Among these, titanium tetra-n-butoxide and 2-ethylhexanoate are preferred from the viewpoint of being cheap and easily available.

[0114] It should be noted that the above reaction can also be carried out in a heating and melting state in a kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader, or a Brabender.

[0115] In addition, the reaction time and temperature in the ring-opening polymerization are not particularly limited, and can be appropriately selected. It is preferably carried out at 50 to 250°C while stirring for 10 seconds to 24 hours, and more preferably at 150 to 230°C while stirring for 50 seconds to 10 hours. If the reaction time is too short compared to the lower limit or the reaction temperature is too low compared to the lower limit, the reaction rate will decrease, and therefore, there is a tendency for unreacted compounds to ooze out of the molded product and cause deterioration of the surface appearance. If the reaction time is too long compared to the upper limit or the reaction temperature is too high compared to the upper limit, there is a tendency for crosslinking to occur between the modified EVOHs, resulting in fish eyes and other poor appearance of the molded product.

[0116] In the modified EVOH obtained in this way, the content of the EVOH unit forming the main chain of the modified EVOH is usually 40 to 99% by mass, preferably 45 to 95% by mass, and particularly preferably 50 to 90% by mass. The content of the structural unit represented by any one of the chemical formulas (1) to (3) grafted to the main chain is usually 1 to 60% by mass, preferably 5 to 55% by mass, and particularly preferably 10 to 50% by mass. It should be noted that the content of the EVOH unit in the modified EVOH and the content of the structural unit represented by any one of the chemical formulas (1) to (3) can be adjusted according to 1 The calculation was performed based on the results of H-NMR measurement.

[0117] In addition, the number average molecular weight of the modified EVOH (measured by GPC and standard polystyrene conversion) is usually 5000 to 300000, preferably 10000 to 200000, and particularly preferably 10000 to 100000. If the number average molecular weight of the modified EVOH is too high, there is a tendency for its melt viscosity to become too high, and if the number average molecular weight is too low, there is a tendency for its melt viscosity to be too low and stable melt molding to be difficult. It should be noted that the number average molecular weight of the modified EVOH can be calculated based on the GPC measurement results.

[0118] The modification rate of the modified EVOH is usually 0.1 to 30 mol%, more preferably 1 to 25 mol%, and particularly preferably 5 to 20 mol%. 1 The calculation was performed based on the results of H-NMR measurement.

[0119] Furthermore, the average value of n in the chemical formulas (1) to (3) in the modified EVOH (i.e., the average chain length of the grafted chains) is usually 1 to 15, preferably 1 to 10, and particularly preferably 1 to 8. If the average chain length of the grafted chains is too long, there is a tendency for strong adhesion and easy adhesion of the molded product. It should be noted that the average chain length can be adjusted according to 1 The calculation was performed based on the results of H-NMR measurement.

[0120] Specifically, by using the following conditions 1 By measuring H-NMR, the modification ratio in the modified EVOH and the average chain length of the grafted chains can be calculated.

[0121] (a) 1 H-NMR measurement conditions

[0122] Internal standard substance: tetramethylsilane

[0123] Solvent: d6-DMSO

[0124] Measured polymer concentration: 5 mass% (sample 0.1 g, solvent 2 mL)

[0125] Measurement temperature: 50℃(323K)

[0126] Irradiation pulse: 45° pulse

[0127] Pulse interval: 10 seconds

[0128] Cumulative times: 16 times

[0129] (b) Attribution of resonance absorption peak

[0130] (I) 0.8~0.9ppm: -CH3 at the end of modified EVOH

[0131] (II) 1.0 to 1.9 ppm: -CH2- in the modified EVOH main chain and adjacent -CH2- in the graft chain

[0132] (III) 2.0 ppm: -CH3 of residual acetyl group in modified EVOH

[0133] (IV) 2.1 to 2.3 ppm: -CH2- adjacent to the carboxyl group of the grafted chain

[0134] (V) 3.3 to 4.0 ppm: -CH- adjacent to -OH of modified EVOH and -CH2- adjacent to -OH of grafted chain

[0135] (VI) 4.0 to 4.7 ppm: -OH of modified EVOH and graft chain, and -CH2- adjacent to the ester bond of the graft chain

[0136] (c) Calculation of modification rate and average length of grafted chains

[0137] The integrated values ​​of the resonance absorption peaks of (I) to (VI) above are used to establish the following simultaneous equations (i) to (vii), and the modified group amount C (mole) and the average chain length n (mole) of the graft chain are calculated from the solutions of the simultaneous equations. Furthermore, the modification rate X (mole %) is calculated from the equation (vii).

[0138] Formula (i): 3×M=[integral value of peak (I)]

[0139] Formula (ii): (2×M)+(2×A)+(4×E)+(2×O)+(6×n+2)×C=[integral value of peak (II)]

[0140] Formula (iii): 3×A=[integral value of peak (III)]

[0141] Formula (iv): 2×n×C=[integral value of peak (IV)]

[0142] Formula (v): O + (2 × C) = [integral value of peak (V)]

[0143] Formula (vi): O+(2×n-1)×C=[integral value of peak (VI)]

[0144] Formula (vii): X=C / (M+A+O+C+E)×100

[0145] Here, M, A, O, C, n, E, and X represent the following values.

[0146] M: The amount of terminal methyl groups of modified EVOH (mole)

[0147] A: Acetyl group amount of modified EVOH (mole)

[0148] O: hydroxyl amount of modified EVOH (mole)

[0149] C: Modified group amount of modified EVOH (mole)

[0150] n: average length of grafted chains (pieces)

[0151] E: Vinyl content of modified EVOH (mole)

[0152] X: modification ratio of modified EVOH (mol%)

[0153] The glass transition temperature (Tg) of the modified EVOH is usually -50 to 60°C, preferably -30 to 45°C, and particularly preferably -10 to 35°C. If the glass transition temperature is too low, blocking of the molded product tends to occur. The glass transition temperature can be measured using a differential scanning calorimeter.

[0154] The content of modified EVOH in the EVOH layer (A) is not particularly limited, and the modified EVOH is preferably the main component (50% by mass or more). The content of modified EVOH is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, and can be 95% by mass or more, or 100% by mass.

[0155] [CFRP layer (B)]

[0156] The CFRP layer (B) includes CFRP.

[0157] CFRP is impregnated with a thermosetting resin, an ultraviolet curable resin and / or a thermoplastic resin, and is obtained, for example, by curing the above resin impregnated into a sheet-like carbon fiber aggregate. Examples of sheet-like carbon fiber aggregates impregnated with the above resins include an object consisting of one sheet (prepreg); or an object consisting of a multilayer structure in which a plurality of prepregs are stacked and integrated by a heating and pressing method. The thickness of a single sheet-like carbon fiber aggregate (prepreg) is not particularly limited, but is preferably 0.5 mm or less. When the CFRP is a multilayer structure of a plurality of prepregs, the thickness can be adjusted to match the intended use.

[0158] As the carbon fiber aggregate, for example, a fabric (plain fabric, twill fabric, satin fabric, etc.) formed of a carbon fiber group, a nonwoven fabric formed of a carbon fiber group, or a carbon fiber aggregate in which a carbon fiber group is arranged in one direction can be used. The carbon fiber group means the amount (number) of carbon fibers required to form various carbon fiber aggregates. The carbon fiber is not particularly limited, and for example, PAN-based carbon fibers, pitch-based carbon fibers, rayon-based carbon fibers, etc. can be used.

[0159] According to some examples, in CFRP, a thermosetting resin or an ultraviolet curable resin covers the surface of the carbon fiber aggregate, and then cures in a state where it enters between the carbon fibers. As the thermosetting resin, a resin used in a known CFRP can be used, and for example, a resin selected from epoxy resin, unsaturated polyester resin, vinyl ester resin, phenolic resin, cyanate resin, and polyimide resin can be used. These can be used alone or in combination of two or more.

[0160] As the ultraviolet curable resin, a resin selected from the monomers, oligomers or mixtures thereof of ultraviolet curable resins can be used. In some examples, as the ultraviolet curable resin, a substance selected from the following substances can be used: a resin selected from the following free radical polymerizable monomers and oligomers of free radical polymerizable monomers; a resin selected from the following cationic polymerizable monomers and oligomers of cationic polymerizable monomers; or a mixture of two or more selected from these monomers and oligomers.

[0161] (Free radical polymerizable monomer)

[0162] Examples of the radical polymerizable compound include compounds having one or more radical polymerizable groups such as a (meth)acryloyl group, a (meth)acryloyloxy group, a (meth)acryloylamino group, a vinyl ether group, a vinyl aryl group, and a vinyloxycarbonyl group in one molecule.

[0163] Examples of the compound having one or more (meth)acryloyl groups in one molecule include 1-butene-3-one, 1-pentene-3-one, 1-hexene-3-one, 4-phenyl-1-butene-3-one, 5-phenyl-1-pentene-3-one, and derivatives thereof.

[0164] Examples of the compound having one or more (meth)acryloyloxy groups in one molecule include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-stearyl (meth)acrylate, n-butoxyethyl (meth)acrylate, butoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol. (Meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, acrylic acid, methacrylic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl -2-Hydroxypropyl phthalate, glycidyl (meth)acrylate, 2-(meth)acryloyloxyethyl acid phosphate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, decane di(meth)acrylate, glycerol di(meth)acrylate, 2-hydroxy-3- (Meth)acryloxypropyl (meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, trifluoroethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, isoamyl (meth)acrylate, isomyristyl (meth)acrylate, γ-(meth)acryloxypropyl trimethoxysilane, 2-(meth)acryloxyethyl isocyanate, 1,1-bis(acryloxy)ethyl isocyanate, 2-(2-(meth)acryloxyethyloxy)ethyl isocyanate, 3-(meth)acryloxypropyl triethoxysilane, and derivatives thereof.

[0165] Examples of the compound having one or more (meth)acryloylamino groups in one molecule include 4-(meth)acryloylmorpholine, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, N-n-butoxymethyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-octyl(meth)acrylamide, and derivatives thereof.

[0166] Examples of the compound having one or more vinyl ether groups in one molecule include 3,3-bis(vinyloxymethyl)oxetane, 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxyisopropyl vinyl ether, 4-hydroxybutyl vinyl ether, 3-hydroxybutyl vinyl ether, 2-hydroxybutyl vinyl ether, 3-hydroxyisobutyl vinyl ether, 2-hydroxyisobutyl vinyl ether, 1-methyl-3-hydroxypropyl vinyl ether, 1-methyl-2-hydroxypropyl vinyl ether, 1-hydroxymethylpropyl vinyl ether, 4-hydroxycyclohexyl vinyl ether, 1,6-hexanediol monoethyl ether, and 1,6-hexanediol monoethyl ether. alkylene ethers, 1,4-cyclohexanedimethanol monovinyl ether, 1,3-cyclohexanedimethanol monovinyl ether, 1,2-cyclohexanedimethanol monovinyl ether, p-phenylenedimethanol monovinyl ether, isophenylenedimethanol monovinyl ether, o-phenylenedimethanol monovinyl ether, diethylene glycol monovinyl ether, triethylene glycol monovinyl ether, tetraethylene glycol monovinyl ether, pentaethylene glycol monovinyl ether, oligoethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, dipropylene glycol monovinyl ether, tripropylene glycol monovinyl ether, tetrapropylene glycol monovinyl ether, pentapropylene glycol monovinyl ether, oligopropylene glycol monovinyl ether, polypropylene glycol monovinyl ether, and derivatives thereof.

[0167] Examples of the compound having one or more vinyl aromatic groups in one molecule include styrene, divinylbenzene, methoxystyrene, ethoxystyrene, hydroxystyrene, vinylnaphthalene, vinylanthracene, 4-vinylphenyl acetate, (4-vinylphenyl)dihydroxyborane, N-(4-vinylphenyl)maleimide, and derivatives thereof.

[0168] Examples of the compound having one or more vinyloxycarbonyl groups in one molecule include isopropenyl formate, isopropenyl acetate, isopropenyl propionate, isopropenyl butyrate, isopropenyl isobutyrate, isopropenyl hexanoate, isopropenyl valerate, isopropenyl isovalerate, isopropenyl lactate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl hexanoate, vinyl octanoate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl pivalate, vinyl octanoate, vinyl monochloroacetate, divinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate, and derivatives thereof.

[0169] (Cationic polymerizable monomer)

[0170] Examples of the cationically polymerizable monomer include compounds having one or more cationically polymerizable groups such as an oxirane ring (oxiranyl group), a vinyl ether group, a vinyl aryl group, and an oxetane group in one molecule.

[0171] Examples of the compound having one or more epoxy rings in one molecule include glycidyl methyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, brominated bisphenol S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, -epoxycyclohexylmethyl (3,4-epoxy)cyclohexanecarboxylate, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane, bis(3,4-epoxycyclohexylmethyl)adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate, methylenebis(3 ,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di(3,4-epoxycyclohexyl methyl) ether, ethylene bis(3,4-epoxycyclohexane carboxylate), epoxy hexahydrophthalic acid dioctyl ester, epoxy hexahydrophthalic acid di(2-ethylhexyl) ester, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl Oily ether, polypropylene glycol diglycidyl ether; polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides to aliphatic polyols such as ethylene glycol, propylene glycol, glycerol, etc.; diglycidyl esters of aliphatic long-chain dibasic acids; monoglycidyl ethers of aliphatic higher alcohols; monoglycidyl ethers of polyether alcohols obtained by adding alkylene oxides to phenol, cresol, butylphenol or these; glycidyl esters of higher fatty acids, etc.

[0172] Examples of the compound having one or more vinyl ether groups in one molecule and the compound having one or more vinyl aromatic groups in one molecule include the same compounds as exemplified as the radical polymerizable compound.

[0173] Examples of the compound having one or more oxetane groups in one molecule include oxetane, 3,3-bis(vinyloxymethyl)oxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, 3-ethyl-3-(hydroxymethyl)oxetane, 3-ethyl-3-[(phenoxy)methyl]oxetane, 3-ethyl-3-(hexyloxymethyl)oxetane, 3-ethyl-3-(chloromethyl)oxetane, Oxetane, 3,3-bis(chloromethyl)oxetane, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, bis{[1-ethyl(3-oxetanyl)]methyl}ether, 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]bicyclohexyl, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]cyclohexane, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, and the like.

[0174] As oligomers of free radical polymerizable monomers and cationic polymerizable monomers, monofunctional or polyfunctional (meth)acrylic oligomers can be listed, and one or more types can be used in combination. As monofunctional or polyfunctional (meth)acrylic oligomers, urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, polyether (meth)acrylate oligomers, polyester (meth)acrylate oligomers, etc. can be listed.

[0175] As the urethane (meth) acrylate oligomer, polycarbonate urethane (meth) acrylate, polyester urethane (meth) acrylate, polyether urethane (meth) acrylate, caprolactone urethane (meth) acrylate, etc. can be listed. The urethane (meth) acrylate oligomer can be obtained by reacting an isocyanate compound obtained by reacting a polyol with a diisocyanate with a hydroxyl group (meth) acrylate monomer. As the aforementioned polyol, polycarbonate diol, polyester polyol, polyether polyol, polycaprolactone polyol can be listed.

[0176] Epoxy (meth) acrylate oligomers are obtained by, for example, esterification reaction of oxirane rings of low molecular weight bisphenol epoxy resins and novolac epoxy resins with acrylic acid. Polyether (meth) acrylate oligomers can be obtained by obtaining a polyether oligomer having hydroxyl groups at both ends by utilizing a dehydration condensation reaction of a polyol, and then esterifying the hydroxyl groups at the two ends with acrylic acid. Polyester (meth) acrylate oligomers can be obtained by, for example, obtaining a polyester oligomer having hydroxyl groups at both ends by utilizing a condensation reaction of a polycarboxylic acid and a polyol, and then esterifying the hydroxyl groups at the two ends with acrylic acid.

[0177] The weight average molecular weight of the monofunctional or polyfunctional (meth)acrylic oligomer is, for example, preferably 100,000 or less, and in a preferred embodiment of the present invention, is 500 to 50,000.

[0178] When the above-mentioned monomer, oligomer or mixture thereof is used, in a preferred embodiment of the present invention, 0.01 to 10 parts by mass of a photopolymerization initiator may be used based on 100 parts by mass of the above-mentioned monomer, oligomer or mixture thereof.

[0179] Thermoplastic resin can be appropriately selected from known thermoplastic resins according to the purpose, for example, thermoplastic resin can also include thermoplastic elastomer. As thermoplastic resin, copolymers including styrene units such as polyamide resins (aliphatic polyamides such as PA6 and PA66, aromatic polyamides), polystyrene, ABS resins, AS resins, polyethylene, copolymers including ethylene units, polypropylene, copolymers including propylene units, other polyolefins, polyvinyl chloride, polyvinylidene chloride, polycarbonate resins, acrylic resins, methacrylic resins, polyester resins, polyacetal resins, polyphenylene sulfide resins, etc. can be listed. They can be used alone or in combination of two or more.

[0180] Thermoplastic elastomers can be appropriately selected from known thermoplastic elastomers according to the application. Examples of thermoplastic elastomers include styrene elastomers, vinyl chloride elastomers, olefin elastomers, urethane elastomers, polyester elastomers, nitrile elastomers, and polyamide elastomers.

[0181] The content of CFRP in the CFRP layer (B) is not particularly limited, and CFRP is preferably the main component (50% by mass or more). The content of CFRP is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, and can be 95% by mass or more, or 100% by mass.

[0182] [Other layers]

[0183] In the present multilayer structure, in addition to the EVOH layer (A) and the CFRP layer (B), other layers may be optionally included. The other layers are not particularly limited, and examples thereof include a polyolefin resin layer including a polyolefin resin, a polyamide resin layer including a polyamide resin (aliphatic polyamides such as PA6 and PA66), an elastomer layer including an elastomer, an adhesive resin layer including an adhesive resin, etc. These layers may be provided in multiple layers or used in combination.

[0184] The polyolefin resin contained in the polyolefin resin layer is not particularly limited, and examples thereof include polypropylene; propylene copolymers obtained by copolymerizing propylene with α-olefins such as ethylene, 1-butene, 1-hexene, and 4-methyl-1-pentene; polyethylenes such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene; ethylene copolymers obtained by copolymerizing ethylene with α-olefins such as 1-butene, 1-hexene, and 4-methyl-1-pentene; poly(1-butene), poly(4-methyl-1-pentene), etc. These may be used alone or in combination of two or more materials having different copolymerization components, physical properties, etc.

[0185] The content of the polyolefin resin contained in the polyolefin resin layer is not particularly limited, and the polyolefin resin is preferably a main component (50% by mass or more). The content of the polyolefin resin is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, most preferably 90% by mass or more, and can be 95% by mass or more, 100% by mass.

[0186] The polyamide resin contained in the polyamide resin layer is not particularly limited. General polyamide resins include homopolymers such as polycaprolactam (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecamide (nylon 11), and polylaurolactam (nylon 12). Examples of the copolymer polyamide resin include polyethylene adipamide (nylon 26), polybutylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene adipamide (nylon 610), polyhexamethylene dodecanediamide (nylon 612), polyoctylene adipamide (nylon 86), polydecamethylene adipamide (nylon 108), caprolactam / laurolactam copolymer (nylon 6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon 6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon 6 / 66), laurolactam / hexamethylenediammonium adipate copolymer (nylon 12 / 66), polyethylene adipamide / hexamethylenediammonium adipate copolymer (nylon 108), and polyisocyanate. Aliphatic polyamides such as poly(ethylene glycol 26 / 66), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 66 / 610), ethylene ammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6 / 66 / 610); aromatic polyamides such as poly(hexamethylene diamine isophthalamide), poly(hexamethylene terephthalamide), poly(meta-phenylene diamine adipamide), isophthalamide / hexamethylene diamine copolymer, poly(p-phenylene terephthalamide), poly(3,4'-diphenyl ether terephthalamide); amorphous polyamides, those obtained by modifying these polyamide resins with aromatic amines such as methylene benzylamine and meta-phenylenediamine, meta-phenylenediamine adipate, etc.

[0187] Alternatively, it may be a terminal-modified polyamide resin thereof, and preferably a terminal-modified polyamide resin. These polyamide-based resins may be used alone or in combination of two or more.

[0188] The content of the polyamide resin contained in the polyamide resin layer is not particularly limited, and the polyamide resin is preferably a main component (50% by mass or more). The content of the polyamide resin is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, most preferably 90% by mass or more, and can be 95% by mass or more, 100% by mass.

[0189] The elastomer contained in the elastomer layer is not particularly limited, and known materials can be used, as long as they are appropriately selected according to the type of the layer to be bonded. For example, thermoplastic elastomers, thermosetting elastomers, etc. can be listed. As thermoplastic elastomers, styrene elastomers, vinyl chloride elastomers, olefin elastomers, urethane elastomers, polyester elastomers, nitrile elastomers, polyamide elastomers, etc. can be listed. As thermosetting elastomers, urethane rubber, silicone rubber, fluororubber, etc. can be listed. They can be used alone or in combination of two or more copolymer components with different compositions, physical properties, etc.

[0190] The content of the elastomer contained in the elastomer layer is not particularly limited, and the elastomer is preferably the main component (50% by mass or more). The content of the elastomer is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, and can be 95% by mass or more, or 100% by mass.

[0191] The adhesive resin contained in the adhesive resin layer is not particularly limited, and known materials can be used, as long as they are appropriately selected according to the type of the layer to be bonded. Representatively, carboxyl-containing modified polyolefin polymers obtained by chemically bonding unsaturated carboxylic acids or their anhydrides to polyolefin resins through addition reactions, grafting reactions, etc. can be listed. For example, maleic anhydride grafted modified polyethylene, maleic anhydride grafted modified polypropylene, maleic anhydride grafted modified ethylene-propylene (block and random) copolymers, maleic anhydride grafted modified ethylene-ethyl acrylate copolymers, maleic anhydride grafted modified ethylene-vinyl acetate copolymers, maleic anhydride modified polycyclic olefin resins, maleic anhydride grafted modified polyolefin resins, etc. can be listed. They can be used alone or in combination with two or more copolymer components having different compositions, physical properties, etc.

[0192] The content of the adhesive resin contained in the adhesive resin layer is not particularly limited, and the adhesive resin is preferably the main component (50% by mass or more). The content of the adhesive resin is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, and can be 95% by mass or more, 100% by mass or more.

[0193] [Multilayer structure]

[0194] The multilayer structure includes an EVOH layer (A) and a CFRP layer (B).

[0195] In the present multilayer structure, a plurality of EVOH layers (A) and a plurality of CFRP layers (B) may be provided.

[0196] The positions of the EVOH layer (A) and the CFRP layer (B) are not particularly limited, but the EVOH layer (A) is preferably laminated on at least one surface of the CFRP layer (B).

[0197] The vibration resistance of the multilayer structure is preferably 10 or less, more preferably 9 or less, and further preferably 8 or less. The vibration resistance refers to the following value: the acceleration of the multilayer structure after being struck by the impact hammer is normalized by the maximum value of the exciting force read by the impact hammer (acceleration / maximum value of the exciting force), and the value obtained by calculating the average amplitude height 50 to 200 ms after the impact.

[0198] The layer structure of the multilayer structure is not particularly limited, and examples thereof include EVOH layer (A) / CFRP layer (B), EVOH layer (A) / CFRP layer (B) / EVOH layer (A), CFRP layer (B) / EVOH layer (A) / CFRP layer (B), EVOH layer (A) / other layer / CFRP layer (B), other layer / EVOH layer (A) / CFRP layer (B), EVOH layer (A) / CFRP layer (B) / other layer, polyolefin resin layer / adhesive resin layer / EVOH layer (A) / adhesive resin layer / polyolefin resin layer / CFRP layer (B), and elastomer layer / EVOH layer (A) / elastomer layer / CFRP layer (B).

[0199] Each layer of the multilayer structure may contain optional additives (hereinafter referred to as "other components") for various purposes, unless the effects of the present invention are significantly impaired. Other components may be used alone or in any combination and ratio.

[0200] Examples of additives include plasticizers, reinforcing agents, fillers, pigments, dyes, lubricants, antioxidants, antistatic agents, ultraviolet absorbers, heat stabilizers, light stabilizers, surfactants, antibacterial agents, desiccants, antiblocking agents, flame retardants, crosslinking agents, curing agents, foaming agents, crystal nucleating agents, etc. The content of these additives in each layer of the multilayer structure is generally 50% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less in total.

[0201] [Method for producing multilayer structure]

[0202] The present multilayer structure is manufactured by laminating at least one layer of the EVOH layer (A) and the CFRP layer (B), respectively, and the manufacturing method is not particularly limited as long as they can be laminated. For example, the present multilayer structure can be obtained by laminating a film or sheet of EVOH with CFRP and other layers as required, and applying heat and pressure to the laminate. As methods for applying heat and pressure, compression molding, autoclave molding, vacuum pressure molding, flat wire winding method, and internal pressure molding method can be used. When the present multilayer structure is manufactured in a manner including other layers, the EVOH layer (A) and other layers can be laminated with the CFRP layer (B) after being pre-laminated, or the other layers can be laminated after the CFRP layer (B) and the EVOH layer (A) are laminated.

[0203] Preferably, the method for producing a multilayer structure comprises the step of laminating the EVOH layer (A) on at least one surface of the CFRP layer (B).

[0204] The lamination of the EVOH layer (A) with other layers can be performed by a known method. Examples include a method of melt extrusion laminating a resin constituting other layers on a film or sheet of EVOH; a method of melt extrusion laminating EVOH on other layers; a method of coextruding EVOH and a resin constituting other layers; a method of dry laminating the EVOH layer (A) with other layers using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound; a method of applying an EVOH solution on other layers and then removing the solvent, etc. Among these, the coextrusion method is preferred from the perspective of cost and environment.

[0205] The manufacturing method of the film, sheet, the resin of other layers etc. of EVOH is not particularly limited, as long as it is a molding method that can be usually applied, then all can be applied. For example, extrusion molding, blow molding, injection molding, thermoforming etc. can be listed. It should be noted that these films, sheets can be objects that have been stretched such as uniaxial stretching, biaxial stretching and / or objects that have been heat-fixed.

[0206] [Vibration-resistant materials for CFRP]

[0207] The EVOH layer (A) used in the present multilayer structure can be used as a vibration-proof material for CFRP, thereby improving the vibration resistance of CFRP.

[0208] The details of the EVOH layer (A) are as described above, and the description thereof is omitted.

[0209] [use]

[0210] The multilayer structure is excellent in vibration resistance and is therefore particularly suitable for use in aircraft, automobiles (especially automobile ceiling materials, etc.), ships and other various transportation equipment parts, sports equipment, entertainment equipment, and the like.

[0211] Example

[0212] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

[0213] It should be noted that, in the examples, "parts" refer to mass standards.

[0214] Prior to the examples, the following materials were prepared.

[0215] (A1) Aliphatic polyester modified EVOH: ethylene structural unit content of 32 mol%, saponification degree of 99.8%, graft modification rate of 6.9 mol%, Tg of 18°C

[0216] (A2) EVOH: 51 mol% ethylene structural unit content, 94.1% saponification degree, 35°C Tg

[0217] (A3) EVOH: 32 mol% ethylene structural unit content, 99.7% saponification degree, 62°C Tg

[0218] (B) CFRP (thermosetting prepreg) (manufactured by Mitsubishi Chemical Corporation, product name: TR3110 369GMP)

[0219] <Example 1>

[0220] (Production of Multilayer Structure)

[0221] The aliphatic polyester-modified EVOH (A1) was supplied to a 40 mm φ single-screw extruder and film-formed at extrusion temperatures C1 / C2 / C3 / C4 / AD / D=180 / 190 / 200 / 200 / 200° C. to obtain an EVOH film having a thickness of 200 μm.

[0222] The CFRP (thermosetting prepreg) (B) was cut into 287 mm in the warp direction and 200 mm in the weft direction, and 4 ply was stacked in the same direction. The obtained EVOH film with a thickness of 200 μm was cut into a size of 200 mm×287 mm and stacked on the stacked CFRP (thermosetting prepreg) (B).

[0223] <Example 2, Comparative Example 1, Reference Example 1>

[0224] A multilayer structure was prepared in the same manner as in Example 1 except that the type of EVOH was changed as described in Table 1.

[0225] <Evaluation of Adhesion to CFRP>

[0226] The multilayer structure was heat-pressed and heat-cured using a hydraulic heating press at 150°C, 5 MPa, and 5 min to obtain a multilayer structure. Thereafter, the adhesion was evaluated based on whether the EVOH layer could be peeled off from the CFRP layer by hand. The case of no peeling was marked as ○ (very good), and the case of peeling was marked as × (poor).

[0227] <Evaluation of vibration resistance>

[0228] The multilayer structure is placed in an autoclave and subjected to heating and pressurization treatment under the following conditions to thermally cure it to obtain a multilayer structure. An acceleration sensor is installed in the center of the obtained multilayer structure, and a rubber tube is used to hang the sample. A hammer having a sensor at the front end that converts force into an electrical signal is used to perform a hammer test. The acceleration of the multilayer structure after being struck by the hammer is standardized using the maximum value of the exciting force read from the hammer (acceleration / maximum value of the exciting force), and the amplitude height average of 50 to 200 ms after the strike is calculated to evaluate the vibration resistance. The lower the value, the better the vibration resistance.

[0229] Autoclave molding conditions

[0230] Pressure: 0.6MPa

[0231] ·Processing temperature / time: 80℃-30 minutes

[0232] 130℃-70min

[0233] Various evaluation results of the multilayer structures of Examples 1 and 2, Comparative Example 1, and Reference Example 1 are shown in Table 1 below.

[0234] [Table 1]

[0235]

[0236] Compared with Reference Example 1 in which EVOH is not used, the vibration resistance of the multilayer structure in Examples 1 and 2 obtained by using EVOH having a Tg within the specified range of the present invention is improved. Compared with Examples 1 and 2, Comparative Example 1 obtained by using EVOH having a Tg outside the specified range of the present invention also has poor adhesion to CFRP and no improvement in vibration resistance.

[0237] Furthermore, as described above, the multilayer structures of Examples 1 and 2 are excellent in vibration resistance, and therefore, automobile parts and aircraft parts including the multilayer structures are also excellent in vibration resistance.

[0238] The above embodiments show specific aspects of the present invention, but the above embodiments are merely illustrative and are not to be construed as limiting. It should be understood that various modifications obvious to those skilled in the art fall within the scope of the present invention.

[0239] Industrial Applicability

[0240] The multilayer structure of the present invention has excellent vibration resistance and is therefore particularly suitable for use in aircraft, automobiles (especially automobile ceiling materials, etc.), ships and other various transportation equipment parts, sports equipment, entertainment equipment, etc.

Claims

1. A multilayer structure comprising an ethylene-vinyl alcohol copolymer layer A and a carbon fiber reinforced plastic layer B, wherein the ethylene-vinyl alcohol copolymer has a glass transition temperature Tg of 0 to 60°C.

2. The multilayer structure according to claim 1, wherein The glass transition temperature Tg of the ethylene-vinyl alcohol copolymer is 0 to 45°C.

3. The multilayer structure according to claim 1, wherein The glass transition temperature Tg of the ethylene-vinyl alcohol copolymer is 0 to 30°C.

4. The multilayer structure according to claim 1, wherein The ethylene-vinyl alcohol copolymer is a modified ethylene-vinyl alcohol copolymer having a structural unit represented by the following chemical formula (1): In the chemical formula (1), X represents an organic chain having a heteroatom, and n represents a positive integer.

5. The multilayer structure according to claim 4, wherein In the chemical formula (1), the heteroatom in X is an oxygen atom, a nitrogen atom or a sulfur atom.

6. The multilayer structure according to claim 4, wherein In the chemical formula (1), n ​​is 1-20.

7. The multilayer structure according to claim 1, wherein The ethylene-vinyl alcohol copolymer layer A is laminated on at least one surface of the carbon fiber reinforced plastic layer B. 8 . The multilayer structure according to claim 1 , which is used for automobile parts or aircraft parts.

9. A method for manufacturing a multilayer structure, comprising: A step of laminating the ethylene-vinyl alcohol copolymer layer A on at least one surface of the carbon fiber reinforced plastic layer B. 10 . An automobile part comprising the multilayer structure according to claim 1 .

11. An aircraft component comprising the multilayer structure according to any one of claims 1 to 7.

12. A vibration-proof material for carbon fiber reinforced plastics, comprising an ethylene-vinyl alcohol copolymer layer, wherein the ethylene-vinyl alcohol copolymer has a glass transition temperature Tg of 0 to 60°C.

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