Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/40—Shaping or impregnating by compression not applied
  • B29C70/50—Shaping or impregnating by compression not applied for producing articles of indefinite length, e.g. prepregs, sheet moulding compounds [SMC] or cross moulding compounds [XMC]
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F16/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical
  • C08F16/38—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical by an acetal or ketal radical
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/48—Isomerisation; Cyclisation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
  • C08J5/0405—Reinforcing macromolecular compounds with loose or coherent fibrous material with inorganic fibres
  • C08J5/042—Reinforcing macromolecular compounds with loose or coherent fibrous material with inorganic fibres with carbon fibres
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/24—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/24—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs
  • C08J5/241—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs using inorganic fibres
  • C08J5/243—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs using inorganic fibres using carbon fibres
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/02—Fibres or whiskers
  • C08K7/04—Fibres or whiskers inorganic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/02—Fibres or whiskers
  • C08K7/04—Fibres or whiskers inorganic
  • C08K7/06—Elements
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
  • C08L29/14—Homopolymers or copolymers of acetals or ketals obtained by polymerisation of unsaturated acetals or ketals or by after-treatment of polymers of unsaturated alcohols
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2433/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
  • C08J2433/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters
  • C08J2433/06—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical

Definitions

• the present invention relates to a carbon fiber reinforced composite material and a method for producing the carbon fiber reinforced composite material.
• Fiber-reinforced plastic one of fiber-reinforced composite materials, is lightweight, high-strength, and high-rigidity. It is used for a wide range of purposes.
• a method for producing fiber-reinforced plastics there is a method of using an intermediate material, that is, a prepreg, in which a reinforcing material made of long fibers (continuous fibers) such as reinforcing fibers is impregnated with a matrix resin. This method has the advantage that it is easy to control the content of the reinforcing fibers in the fiber-reinforced plastic and that the content can be designed to be high.
• Epoxy resins are preferably used as matrix resins for such fiber-reinforced composite materials because of their excellent moldability. Epoxy resins are used in a wide range of industrial fields because fiber-reinforced composite materials with excellent mechanical properties and heat resistance can be obtained even after curing.
• Patent Document 1 describes a prepreg containing predetermined amounts of reinforcing fiber, epoxy resin, carboxyl group-containing polyvinyl formal resin, and amine curing agent.
• Patent Document 2 describes a prepreg for a fiber-reinforced composite material containing predetermined amounts of an epoxy resin, a thermoplastic resin soluble in the epoxy resin, and a latent curing agent.
• Patent Document 3 describes a prepreg obtained by impregnating reinforcing fibers with an epoxy resin composition containing an epoxy compound, a curing agent, and a polyvinyl acetal resin.
• the resulting prepreg has insufficient tackiness (surface adhesiveness), resulting in a problem of reduced handleability. Moreover, the resulting prepreg has poor interfacial adhesion between the reinforcing fibers and the matrix resin, resulting in a problem that sufficient performance cannot be obtained. Furthermore, there is a problem that the toughness of the obtained prepreg is insufficient and the mechanical strength is lowered. In addition, there is also the problem that many voids are generated in the obtained prepreg, and the quality of the obtained carbon fiber reinforced composite material deteriorates.
• the present invention provides a carbon fiber reinforced composite that has excellent tackiness, compatibility with epoxy resin, and interfacial adhesion, as well as realizing high mechanical strength and reducing the void generation rate. It is an object of the present invention to provide a material and a method of manufacturing a carbon fiber reinforced composite material.
• the present disclosure (1) is a carbon fiber reinforced composite material containing carbon fiber, an epoxy resin, a curing agent, and a thermoplastic resin, wherein the mixture of the epoxy resin and the thermoplastic resin has a viscosity at 30 ° C. , a ratio of viscosity at 90° C. (viscosity at 30° C./viscosity at 90° C.) of 100 or more.
• the present disclosure (2) is the carbon fiber reinforced composite material according to the present disclosure (1), wherein the thermoplastic resin has a glass transition temperature of 60° C. or higher.
• the present disclosure (3) is the carbon fiber reinforced composite material according to the present disclosure (1) or (2), wherein the thermoplastic resin is a polyvinyl acetal resin.
• the polyvinyl acetal resin contains a structural unit represented by the following formula (1), and R 1 in the following formula (1) is an alkyl group having 1 or more carbon atoms and/or carbon
• the carbon fiber reinforced composite material according to (3) of the present disclosure which is an alkyl group having a number of 3 or more.
• R 1 represents a hydrogen atom or an alkyl group having 1 or more carbon atoms.
• R 1 may be the same or may be a combination of different ones.
• the present disclosure (5) is the carbon fiber reinforced composite material according to the present disclosure (3) or (4), wherein the polyvinyl acetal resin contains a structural unit having an acid-modified group.
• the present disclosure (6) is the carbon fiber reinforced composite material according to the present disclosure (5), wherein the polyvinyl acetal resin has a content of 0.01 to 20 mol % of structural units having an acid-modified group.
• This disclosure (7) is the carbon fiber reinforced composite material according to any one of this disclosure (1) to (6), which is used as a prepreg.
• the present disclosure (8) includes at least a step of producing a resin composition containing an epoxy resin, a curing agent, and a thermoplastic resin, and a step of compounding the resin composition with carbon fibers, A method for producing a carbon fiber reinforced composite material, wherein the mixture of the epoxy resin and the thermoplastic resin has a ratio of viscosity at 30° C. to viscosity at 90° C. (viscosity at 30° C./viscosity at 90° C.) of 100 or more. be.
• the present invention will be described in detail below.
• the present inventors have found a carbon fiber reinforced composite material containing carbon fiber, an epoxy resin, a curing agent, and a thermoplastic resin, wherein the mixture of the epoxy resin and the thermoplastic resin has a predetermined viscosity characteristic. have excellent tackiness and interfacial adhesion, realize high mechanical strength, and can reduce the void generation rate, and have completed the present invention.
• the present invention contains carbon fiber, an epoxy resin, a curing agent, and a thermoplastic resin, and the mixture of the epoxy resin and the thermoplastic resin (hereinafter also simply referred to as the mixture) has a viscosity at 30 °
• the viscosity ratio (viscosity at 30° C./viscosity at 90° C.) is 100 or more.
• a tough carbon fiber reinforced composite material with excellent tackiness and low void generation rate can be produced.
• a preferable lower limit of the viscosity ratio of the mixture is 110, and a more preferable lower limit is 120.
• a preferable upper limit of the viscosity ratio is 600, and a more preferable upper limit is 430.
• the above viscosity was measured using a rheometer on a sample (mixture) obtained by heating and dissolving an epoxy resin and a thermoplastic resin at a mixing ratio similar to that of the carbon fiber reinforced composite material of the present invention at 150°C. can be obtained.
• it means the viscosity at 30° C. and 90° C. measured under the conditions of using a 20 mm parallel plate, cooling rate: 5° C./min, number of revolutions: 100 rpm, and gap: 500 ⁇ m.
• the epoxy resin and thermoplastic resin used in the above viscosity measurement mean the epoxy resin and thermoplastic resin contained in the carbon fiber reinforced composite material.
• the mixing ratio of the epoxy resin and the thermoplastic resin when measuring the viscosity can be measured in the range of 100:43 to 100:0.1 for the epoxy resin:thermoplastic resin. More preferably, the above range is 100:30 to 100:0.1.
• the viscosity ratio of the mixture can be adjusted according to the type of thermoplastic resin, average degree of polymerization, glass transition temperature, type of epoxy resin, and the like. Moreover, when using a polyvinyl acetal resin as a thermoplastic resin, it can also be adjusted by the degree of acetalization, the amount of hydroxyl groups, the amount of acetyl groups, and the like. In particular, when an epoxy resin having a rigid skeleton is used, the viscosity at 30° C. increases, and the viscosity ratio can be increased. Specifically, when an aromatic epoxy resin is used, the viscosity ratio can be made larger than when an alicyclic epoxy resin is used.
• thermoplastic resin When a polyvinyl acetal resin is used as the thermoplastic resin, reducing the number of carbon atoms in the acetal group (the number of carbon atoms in the starting aldehyde) increases the viscosity at 30° C., increasing the viscosity ratio.
• the preferred lower limit of the viscosity of the mixture at 30° C. is 30 Pa ⁇ s, and the preferred upper limit is 1500 Pa ⁇ s. Within the above range, appropriate tackiness can be maintained after impregnation of carbon fibers, and handling properties can be improved.
• a more preferable lower limit of the viscosity at 30° C. is 50 Pa ⁇ s, and a more preferable upper limit is 1300 Pa ⁇ s.
• the preferred lower limit of the viscosity of the mixture at 90° C. is 0.1 Pa ⁇ s, and the preferred upper limit is 5.0 Pa ⁇ s. When the content is within the above range, the viscosity becomes optimum when the carbon fiber is impregnated, and the generation rate of voids can be suppressed.
• a more preferable lower limit of the viscosity at 90° C. is 1.0 Pa ⁇ s, and a more preferable upper limit is 4.0 Pa ⁇ s.
• the carbon fiber reinforced composite material of the present invention contains a thermoplastic resin.
• the thermoplastic resin include polyolefin, polyester, (meth)acrylic resin, polyamide, polyurethane, ABS resin, AES resin, AAS resin, MBS resin, anion/styrene copolymer, styrene/methyl (meth)acrylate copolymer, Polymer, polystyrene, polycarbonate, polyphenylene oxide, phenoxy resin, polyphenylene sulfide, polyimide, polyetheretherketone, polyethersulfone, polysulfone, polyarylate, polyetherketones, polyethernitrile, polythioethersulfone, polybenzimidazole, poly Examples include carbodiimide, polyvinyl alcohol resin, polyvinyl acetal resin, and the like.
• polyolefins polyolefins, polyesters, (meth)acrylic resins, polyvinyl alcohol resins, and polyvinyl acetal resins are preferred.
• the polyolefin include polyethylene, polypropylene, ethylene/vinyl acetate copolymer, ethylene/(meth)acrylic acid copolymer, ethylene/methyl(meth)acrylate copolymer, ethylene/ethyl(meth)acrylate. copolymers, ethylene/vinyl alcohol copolymers, ethylene/ethyl (meth)acrylate/maleic anhydride copolymers, and the like.
• the (meth)acrylic resin include polymethyl (meth)acrylate.
• thermoplastic resin it is preferable to use a resin having a Tg (glass transition temperature) of 60° C. or higher, which will be described later, from the viewpoint of heat resistance, and among these, a polyvinyl acetal resin is preferable.
• Tg glass transition temperature
• the above thermoplastic resins may be used alone, or two or more of them may be used in combination.
• the polyvinyl acetal resin preferably contains a structural unit represented by the following formula (1).
• R 1 represents a hydrogen atom or an alkyl group having 1 or more carbon atoms. Also, R 1 may be the same or may be a combination of different ones.
• R 1 is a hydrogen atom or an alkyl group having 1 or more carbon atoms.
• R 1 is preferably an alkyl group having 1 or more carbon atoms.
• the number of carbon atoms is preferably 1 or more, and preferably 6 or less.
• R 1 in formula (1) is preferably an alkyl group having 1 or more carbon atoms and/or an alkyl group having 3 or more carbon atoms.
• the above R 1 may be the same or may be a combination of different ones.
• the above R 1 is a combination of different ones, it is preferably a combination of an alkyl group having 1 or more carbon atoms and an alkyl group having 3 or more carbon atoms.
• the alkyl group is not particularly limited as long as it is an alkyl group having 1 or more carbon atoms. Examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group and sec-butyl group. group, tert-butyl group, and the like.
• pentyl group hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group and the like.
• a methyl group and an n-propyl group are preferred.
• the preferable lower limit of the content of the structural unit having an acetal group represented by the general formula (1) is 30 mol%, and the preferable upper limit thereof is 85 mol%.
• the acetal group content is 30 mol % or more, a polyvinyl acetal resin having excellent toughness can be obtained.
• the amount of acetal groups is 85 mol % or less, the compatibility with epoxy resins can be improved.
• a more preferable lower limit of the acetal group content is 60 mol %, and a more preferable upper limit thereof is 80 mol %.
• the acetal group of the polyvinyl acetal resin is obtained by acetalizing the structural unit having two hydroxyl groups of the polyvinyl alcohol resin.
• the amount of acetal groups is calculated by employing a method of counting structural units having two hydroxyl groups.
• the preferred lower limit of the content of the structural unit (hereinafter also referred to as “degree of acetoacetalization”) is 5 mol%, which is preferred.
• the upper limit is 85 mol%.
• the compatibility with the epoxy resin can be maintained and excellent viscosity characteristics can be obtained.
• the preferred lower limit of the content of the structural unit (hereinafter also referred to as "butyralization degree”) is 0.5. 1 mol %, the preferred upper limit is 80 mol %.
• the compatibility with the epoxy resin can be maintained and excellent viscosity characteristics can be obtained.
• the ratio of the degree of acetoacetalization to the degree of butyralization is preferably 0.06 or more and 850 or less. Moreover, it is more preferable that the ratio is 0.1 or more and 375 or less.
• the preferable lower limit of the content of the structural unit having a hydroxyl group represented by the general formula (2) (hereinafter also referred to as "hydroxyl group content”) is 15.0 mol%, and the preferable upper limit is 45.0. in mol %.
• the amount of hydroxyl groups is 15.0 mol % or more, a polyvinyl acetal resin having excellent adhesiveness can be obtained. Compatibility with an epoxy resin can fully be improved as the said amount of hydroxyl groups is 45.0 mol% or less.
• a more preferable lower limit to the amount of hydroxyl groups is 20 mol %, and a more preferable upper limit is 38 mol %.
• the content of the structural unit having an acetyl group represented by the general formula (3) (hereinafter also referred to as "acetyl group content”) preferably has a lower limit of 0.1 mol% and a preferred upper limit of 25. in mol %.
• acetyl group content preferably has a lower limit of 0.1 mol% and a preferred upper limit of 25. in mol %.
• the amount of acetyl groups is 0.1 mol % or more, it is possible to suppress an increase in viscosity due to intramolecular and intermolecular hydrogen bonding of hydroxyl groups in the polyvinyl acetal resin.
• the amount of acetyl groups is 25 mol % or less, handleability can be improved without excessively lowering the heat resistance of the polyvinyl acetal resin.
• a more preferable lower limit of the acetyl group content is 0.5 mol %, and a more preferable upper limit thereof is 15 mol %.
• the total amount of the acetal group content, the hydroxyl group content and the acetyl group content is preferably more than 95 mol %. More preferably, it is 96 mol % or more.
• the polyvinyl acetal resin preferably contains a structural unit having an acid-modified group.
• a structural unit having the above acid-modified group By having a structural unit having the above acid-modified group, the compatibility with the epoxy resin is improved and the toughness is improved.
• the adhesion to the carbon fibers is improved, separation between the matrix resin and the carbon fibers in the composite material is suppressed. This can contribute to reducing defects and improving mechanical strength.
• Examples of the acid-modified group include carboxyl group, sulfonic acid group, maleic acid group, sulfinic acid group, sulfenic acid group, phosphoric acid group, phosphonic acid group, and salts thereof.
• the structural unit having an acid-modifying group may have a structure in which two acid-modifying groups are bonded to the same carbon constituting the main chain, or a structure in which one acid-modifying group is bonded to the carbon constituting the main chain. good too.
• the acid-modified group may be directly bonded to the carbon atoms constituting the main chain, or may be bonded to the carbon atoms constituting the main chain via an alkylene group.
• the acid-modifying group may have a structure in which the acid-modifying group is bonded to the carbon constituting the acetal group.
• the alkylene group is an alkylene group having 1 to 10 carbon atoms. is preferred, an alkylene group having 1 to 5 carbon atoms is more preferred, and an alkylene group having 1 to 3 carbon atoms is even more preferred.
• Examples of the alkylene group having 1 to 10 carbon atoms include a linear alkylene group, a branched alkylene group, and a cyclic alkylene group.
• Examples of the linear alkylene group include methylene group, vinylene group, n-propylene group, tetramethylene group, pentamethylene group, hexamethylene group, octamethylene group and decamethylene group.
• Examples of the branched alkylene group include a methylmethylene group, a methylethylene group, a 1-methylpentylene group and a 1,4-dimethylbutylene group.
• cyclic alkylene group examples include a cyclopropylene group, a cyclobutylene group and a cyclohexylene group.
• a linear alkylene group is preferred, a methylene group, vinylene group and n-propylene group are more preferred, and a methylene group and vinylene group are still more preferred.
• the structural unit containing the carboxyl group includes, for example, a structural unit represented by the following formula (4-1) and a structure represented by the following formula (4-2). units, structural units represented by the following formula (4-3), and the like.
• R 2 and R 3 each independently represent an alkylene group having 0 to 10 carbon atoms
• X 1 and X 2 each independently represent a hydrogen atom, a metal atom or a methyl group.
• R 4 , R 5 and R 6 are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms
• R 7 is an alkylene group having 0 to 10 carbon atoms
• X 3 is It represents a hydrogen atom, a metal atom or a methyl group.
• R 2 , R 3 or R 7 is an alkylene group having 0 carbon atoms means that R 2 , R 3 or R 7 is a single bond.
• R 8 represents an alkylene group having 0 to 10 carbon atoms
• X 4 represents a hydrogen atom, a metal atom or a methyl group.
• the carbon number of 0 means the case where an alkylene group does not exist, that is, it means that it does not have an alkylene group and is directly bonded.
• X 1 and X 2 are a metal atom
• the metal atom include a sodium atom, a lithium atom, and a potassium atom.
• a sodium atom is preferred.
• the polyvinyl acetal resin preferably has a structural unit represented by formula (4-1).
• the polyvinyl acetal resin has the structural unit represented by the formula (4-1)
• the compatibility with the epoxy resin can be improved.
• X3 is a metal atom
• examples of the metal atom include sodium atom, lithium atom, potassium atom and the like. Among them, a sodium atom is preferred. The same applies when X4 is a metal atom.
• the content of structural units having acid-modified groups (hereinafter also referred to as "acid-modified group content”) preferably has a lower limit of 0.01 mol% and a preferred upper limit of 20 mol%.
• the amount of the acid-modified group is 0.01 mol % or more, the effect of having the acid-modified group in the polyvinyl acetal resin can be sufficiently exhibited, and the adhesiveness can be further improved.
• the amount of acid-modified group is 20 mol % or less, tackiness and toughness can be further improved.
• a more preferable lower limit of the amount of acid-modified groups in the polyvinyl acetal resin is 0.05 mol %, a more preferable upper limit is 15 mol %, a still more preferable lower limit is 0.1 mol %, and a still more preferable upper limit is 10 mol %.
• the acid-modified group content of the polyvinyl acetal resin means the ratio of structural units having an acid-modified group to the total structural units of the polyvinyl acetal resin.
• the polyvinyl acetal resin preferably has an average degree of polymerization of 2500 or less.
• the average degree of polymerization is 2500 or less, sufficient mechanical strength can be imparted. Further, when the average degree of polymerization is 1000 or less, the solubility in organic solvents can be sufficiently improved, and the coatability and dispersibility can be further improved.
• a more preferable lower limit of the average degree of polymerization is 150, and a more preferable upper limit is 1,000.
• the average degree of polymerization is the same as the average degree of polymerization of the raw material polyvinyl alcohol resin.
• the average degree of polymerization of the starting polyvinyl alcohol resin can be measured according to JIS K6726-1994.
• the thermoplastic resin preferably has a glass transition temperature (Tg) of 60° C. or higher, more preferably 68° C. or higher, and even more preferably 75° C. or higher.
• Tg glass transition temperature
• a particularly preferable lower limit of the glass transition temperature is 80°C.
• a preferable upper limit of the glass transition temperature is 200°C, a more preferable upper limit is 150°C, and a further preferable upper limit is 120°C.
• the glass transition temperature can be measured using a differential scanning calorimeter (DSC).
• the polyvinyl acetal resin can usually be produced by acetalizing a polyvinyl alcohol resin.
• the method of acetalization is not particularly limited, and conventionally known methods can be used. Examples include a method of adding various aldehydes to the solution.
• the production method may be a method of acetalizing a polyvinyl alcohol resin containing a structural unit having an acid-modified group.
• a method of acetalizing unmodified polyvinyl alcohol and post-modifying it may also be used.
• aldehyde examples include linear, branched, cyclic saturated, cyclic unsaturated or aromatic aldehydes having 1 to 19 carbon atoms. Specific examples include formaldehyde, acetaldehyde, propionylaldehyde, n-butyraldehyde, isobutyraldehyde, tert-butyraldehyde, benzaldehyde, cyclohexylaldehyde and the like.
• the above aldehydes may be used alone, or two or more of them may be used in combination.
• aldehydes other than formaldehyde, cyclic saturated, cyclic unsaturated or aromatic aldehydes are preferred, and acetaldehyde and n-butyraldehyde are particularly preferred.
• the amount of the aldehyde to be added can be appropriately set according to the amount of acetal groups in the desired polyvinyl acetal resin.
• the acetalization reaction is efficiently performed, and unreacted aldehyde It is also preferable because it is easy to remove.
• polyvinyl alcohol resin conventionally known polyvinyl alcohol resins such as resins produced by saponifying polyvinyl acetate with an alkali, an acid, aqueous ammonia or the like can be used.
• the above polyvinyl alcohol resin may be completely saponified, but it is not necessary to be completely saponified if at least one unit having two consecutive hydroxyl groups with respect to the meso- and racemo-positions is present in at least one of the main chains.
• a partially saponified polyvinyl alcohol-based resin is not necessary to be completely saponified if at least one unit having two consecutive hydroxyl groups with respect to the meso- and racemo-positions is present in at least one of the main chains.
• polyvinyl alcohol resin copolymers of vinyl alcohol and monomers copolymerizable with vinyl alcohol, such as ethylene-vinyl alcohol copolymer resins and partially saponified ethylene-vinyl alcohol copolymer resins, can also be used.
• examples of the polyvinyl acetate-based resin include ethylene-vinyl acetate copolymers.
• the polyvinyl acetal resin is preferably an acetalized polyvinyl alcohol resin having a degree of saponification of 75 mol % or more. Moreover, the degree of saponification is more preferably 85 mol % or more, and preferably 99.5 mol % or less.
• the holding time after the reaction is preferably 1.5 hours or longer, more preferably 2 hours or longer, although it depends on other conditions.
• the acetalization reaction can be allowed to proceed sufficiently by setting the holding time as described above.
• the holding temperature after the reaction is preferably 15° C. or higher, more preferably 20° C. or higher. By setting it as the said holding temperature, an acetalization reaction can fully be advanced.
• the polyvinyl alcohol resin usually contains a carboxylate, which is a basic component generated during saponification, it is preferable to use it after washing away or neutralizing it.
• the washing method in the washing step include a method of extracting basic components with a solvent, a method of dissolving the resin in a good solvent and then adding a poor solvent to reprecipitate only the resin, and a method of reprecipitating only the resin. and a method of adding an adsorbent to a solution containing to adsorb and remove basic components.
• Examples of the neutralizing agent used in the neutralization step include mineral acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; inorganic acids such as carbonic acid; and carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid and hexanoic acid. , aliphatic sulfonic acids such as methanesulfonic acid and ethanesulfonic acid, aromatic sulfonic acids such as benzenesulfonic acid, and phenols such as phenol.
• the content of the thermoplastic resin in the carbon fiber reinforced composite material of the present invention is preferably 0.01 parts by weight or more and 40.0 parts by weight or less with respect to 100 parts by weight of the epoxy resin. When the content of the thermoplastic resin is within the above range, the mechanical strength of the obtained carbon fiber reinforced composite material can be sufficiently increased. Further, the content of the thermoplastic resin in the carbon fiber reinforced composite material of the present invention is preferably 0.001% by weight or more and preferably 35% by weight or less with respect to the entire composite material. When the content of the thermoplastic resin is within the above range, the mechanical strength of the obtained carbon fiber reinforced composite material can be sufficiently increased.
• the carbon fiber reinforced composite material of the present invention contains carbon fibers.
• the carbon fiber include PAN-based carbon fiber, pitch-based carbon fiber, cellulose-based carbon fiber, and vapor-grown carbon fiber.
• the carbon fiber As the form of the carbon fiber, twisted yarn, untwisted yarn, non-twisted yarn, etc. can be used. Untwisted yarn or untwisted yarn, which has a good balance between the formability and strength characteristics of the carbon fiber reinforced composite material, is preferably used because it causes deterioration of the mechanical properties of the material.
• the carbon fiber may be subjected to an oxidation treatment to introduce an oxygen-containing functional group in order to improve adhesion to the matrix resin.
• Gas-phase oxidation, liquid-phase oxidation, and liquid-phase electrolytic oxidation are used as the oxidation treatment method. Liquid-phase electrolytic oxidation is preferably used from the viewpoint of high productivity and uniform treatment.
• the carbon fiber preferably has a single fiber fineness of 0.2 to 2.0 dtex, more preferably 0.4 to 1.8 dtex.
• the single fiber fineness is 0.2 dtex or more, the carbon fibers are less likely to be damaged due to contact with guide rollers during twisting, and the same damage is less likely to occur during the resin composition impregnation process.
• the single fiber fineness is 2.0 dtex or less, the carbon fibers can be sufficiently impregnated with the resin composition, resulting in improved fatigue resistance.
• the fineness of the carbon fiber is preferably 50 to 1800 tex.
• the number of filaments in one fiber bundle of the carbon fibers is preferably in the range of 2,500 to 100,000.
• the fiber arrangement tends to meander, which tends to cause a decrease in strength. Further, if the number of filaments exceeds 100,000, it may be difficult to impregnate the prepreg with the resin during fabrication or molding.
• the number of filaments is more preferably in the range of 2800-80000.
• the average fiber diameter of the carbon fibers is preferably 2 ⁇ m or more, more preferably 3 ⁇ m or more, preferably 30 ⁇ m or less, and more preferably 26 ⁇ m or less.
• the average fiber length of the carbon fibers is preferably 2 mm or longer, more preferably 4 mm or longer, preferably 100 mm or shorter, and more preferably 80 mm or shorter.
• the form of the carbon fiber is not particularly limited, but examples thereof include fibrous form, woven fabric, knitted fabric, sheet form of nonwoven fabric, and the like.
• the basis weight of the fibers is preferably 100 g/m 2 or more, more preferably 350 g/m 2 or more, and preferably 1000 g/m 2 or less. It is more preferably 650 g/m 2 or less.
• the density of the carbon fibers is preferably 1.0 g/cm 3 or more and 3.0 g/cm 3 or less.
• the carbon fiber content in the carbon fiber reinforced composite material of the present invention is preferably 50% by weight or more and preferably 85% by weight or less. When the carbon fiber content is within the above range, the mechanical strength of the obtained carbon fiber reinforced composite material can be sufficiently increased. Also, the content of the carbon fiber is preferably 150 to 550 parts by weight with respect to 100 parts by weight of the epoxy resin.
• the carbon fiber reinforced composite material of the present invention contains epoxy resin.
• cross-linking can be achieved by applying energy such as heating, and high adhesiveness can be achieved.
• epoxy resin examples include monofunctional epoxy compounds, bifunctional epoxy compounds, and polyfunctional epoxy compounds such as trifunctional or higher epoxy compounds, and more preferably include monofunctional epoxy compounds and bifunctional epoxy compounds.
• Examples of the monofunctional epoxy compound include (meth)acrylic acid esters having a glycidyl group, aliphatic epoxy resins, aromatic epoxy resins, and the like. Among them, it is preferable to contain a (meth)acrylic acid ester having a glycidyl group.
• Examples of the (meth)acrylic ester having a glycidyl group include glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate glycidyl ether, 2-hydroxypropyl (meth)acrylate glycidyl ether, 3-hydroxypropyl (meth)acrylate ) acrylate glycidyl ether, 4-hydroxybutyl (meth)acrylate glycidyl ether, polyethylene glycol-polypropylene glycol (meth)acrylate glycidyl ether, and the like.
• Examples of the aliphatic epoxy resin include glycidyl ethers of aliphatic alcohols such as butyl glycidyl ether and lauryl glycidyl ether.
• Examples of the aromatic epoxy resin include phenylglycidyl ether and 4-t-butylphenylglycidyl ether. Among them, (meth)acrylic acid esters having glycidyl groups and aromatic epoxy resins are preferable.
• bifunctional epoxy compound examples include phenol novolac type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, alkylphenol type epoxy resin, resorcinol type epoxy resin, and bifunctional naphthalene type epoxy resin.
• Bifunctional aromatic epoxy resins such as resins, bifunctional alicyclic epoxy resins such as dicyclopentadiene dimethanol diglycidyl ether, polyalkylene glycol diglycidyl ethers such as polypropylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether , diglycidyl phthalate, diglycidyl tetrahydrophthalate, difunctional glycidyl ester type epoxy resins such as diglycidyl ester of dimer acid, diglycidyl aniline, difunctional glycidyl amine type epoxy resins such as diglycidyl toluidine, bifunctional heterocyclic Epoxy resins, bifunctional diarylsulfone type epoxy resins, hydroquinone type epoxy resins such as hydroquinone diglycidyl ether, 2,5-di-tert-butylhydroquinone diglycidyl ether, resorcinol diglycidyl ether, butane
• bifunctional epoxy compounds may be used alone or in combination of two or more.
• bifunctional aromatic epoxy resins are preferred, and phenol novolac type epoxy resins, bisphenol A type epoxy resins, and bisphenol F type epoxy resins are more preferred.
• bifunctional alicyclic epoxy resins such as dicyclopentadiene dimethanol diglycidyl ether, and polyalkylene glycol diglycidyl ethers such as polypropylene glycol diglycidyl ether may also be used.
• tri- or more functional epoxy compounds examples include tri- or more functional aromatic epoxy resins such as tri- or more functional phenol novolac epoxy resins, tri- or more functional alicyclic epoxy resins, and tri- or more functional glycidyl ester type epoxy resins.
• Epoxy resins tri- or higher functional glycidylamine type epoxy resins such as tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenylmethane, triglycidyl-m-aminophenylmethane, tetraglycidyl-m-xylylenediamine, tri- or higher functional Heterocyclic epoxy resins, tri- or more functional diarylsulfone type epoxy resins, tri- or more functional alkylene glycidyl ether compounds such as glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tri- or more functional glycidyl Examples include group-containing hydantoin compounds, tri- or more functional glycidyl group-containing siloxanes, modified products thereof, and the like.
• the content of the epoxy resin in the carbon fiber reinforced composite material of the present invention preferably has a lower limit of 20% by weight, a more preferred lower limit of 25% by weight, a preferred upper limit of 50% by weight, and a more preferred upper limit of 45% by weight.
• the epoxy equivalent (molecular weight per epoxy group) of the epoxy resin preferably has a lower limit of 100 and a preferred upper limit of 5,000.
• the molecular weight of the epoxy resin has a preferred lower limit of 100 and a preferred upper limit of 70,000.
• the ratio of the thermoplastic resin content to the epoxy resin content preferably has a lower limit of 0.0001.
• a more preferable lower limit is 0.001, a preferable upper limit is 0.4, and a more preferable upper limit is 0.35.
• the carbon fiber reinforced composite material of the present invention contains a curing agent.
• the curing agent include phenol-based curing agents, thiol-based curing agents, amine-based curing agents, imidazole-based curing agents, acid anhydride-based curing agents, cyanate-based curing agents, and active ester-based curing agents.
• amine-based curing agents are preferred.
• amine curing agent examples include trimethylamine, triethylamine, N,N-dimethylpiperazine, triethylenediamine, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol. , 1,8-diazabicyclo(5,4.0)-undecene-7, 1,5-diazabicyclo(4,3.0)-nonene-5 and the like.
• imidazole curing agent examples include imidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole and the like.
• the content of the curing agent in the carbon fiber reinforced composite material of the present invention has a preferred lower limit of 0.5 parts by weight, a more preferred lower limit of 1.0 parts by weight, and a preferred upper limit of 100 parts by weight, and a more preferable upper limit is 50 parts by weight. Moreover, the content of the curing agent in the carbon fiber reinforced composite material of the present invention is preferably 0.1 to 25% by weight.
• the carbon fiber reinforced composite material of the present invention may further contain a curing accelerator and an organic solvent.
• the curing accelerator include phosphorus compounds, amine compounds and organometallic compounds.
• the content of the curing accelerator in the carbon fiber reinforced composite material of the present invention has a preferred lower limit of 0.1 parts by weight, a more preferred lower limit of 0.5 parts by weight, and a preferred upper limit of 0.5 parts by weight with respect to 100 parts by weight of the epoxy resin. is 30 parts by weight, and the more preferred upper limit is 10 parts by weight.
• Examples of the organic solvent include ketones, alcohols, aromatic hydrocarbons, esters and the like.
• Examples of the ketones include acetone, methyl ethyl ketone, dipropyl ketone and diisobutyl ketone.
• Examples of alcohols include methanol, ethanol, isopropanol, and butanol. Toluene, xylene, etc. are mentioned as said aromatic hydrocarbons.
• esters examples include methyl propionate, ethyl propionate, butyl propionate, methyl butanoate, ethyl butanoate, butyl butanoate, methyl pentanoate, ethyl pentanoate, butyl pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, 2-ethylhexyl acetate, 2-ethylhexyl butyrate and the like.
• methyl cellosolve, ethyl cellosolve, butyl cellosolve, terpineol, dihydroterpineol, butyl cellosolve acetate, butyl carbitol acetate, terpineol acetate, dihydroterpineol acetate and the like can also be used.
• the preferable upper limit of the content of the organic solvent in the carbon fiber reinforced composite material of the present invention is 5.0% by weight, and 0% by weight is particularly preferable.
• the carbon fiber reinforced composite material of the present invention may contain resins other than epoxy resins and thermoplastic resins within a range that does not impair the effects of the present invention.
• the content of other resins is preferably 10% by weight or less.
• the carbon fiber reinforced composite material of the present invention may further include a tackifying resin, an adhesive strength modifier, an emulsifier, an antioxidant, a softening agent, a filler, a pigment, a dye, and a silane coupling agent, as long as the effects of the present invention are not impaired. It may contain known additives such as agents, antioxidants, surfactants, and waxes.
• the method for producing the carbon fiber reinforced composite material of the present invention is not particularly limited.
• a method for producing a carbon fiber reinforced composite material can be used.
• the epoxy resin, the curing agent, and the thermoplastic resin and various additives added as necessary are mixed in a ball mill, blender mill, three rolls, disper, planetary mixer, etc. A method of impregnating the carbon fiber after mixing using various mixers, and the like can be mentioned.
• the epoxy resin and the thermoplastic resin may be mixed and then the curing agent may be added, or the epoxy resin, the curing agent, and the thermoplastic resin are added at the same time. It may be produced by
• Examples of the method for combining the resin composition with the carbon fiber include a method of impregnating the carbon fiber. Specifically, for example, autoclave method, press method, hand lay-up method, pultrusion method, filament winding method, RTM method, pin winding method, infusion method, hot (cold) press method, spray-up method, continuous press method. etc.
• Carbon fiber reinforced composite materials are not particularly limited, and they can be used for structural materials for aircraft, automobile applications, ship applications, sports applications, and other general industrial applications such as windmills and rolls. Among them, however, application to prepregs and sheet molding compounds (SMC) as intermediate members is preferable, and application to those using prepregs is particularly preferable.
• SMC sheet molding compounds
• a carbon fiber reinforced composite material having excellent tackiness, compatibility with epoxy resin and interfacial adhesion, realizing high mechanical strength and reducing the void generation rate, and carbon A method for manufacturing a fiber-reinforced composite material can be provided.
• Example 1 (Production of polyvinyl acetal resin) 2700 g of pure water was added to 250 g of polyvinyl alcohol resin having an average degree of polymerization of 800 and a degree of saponification of 93.0 mol %, and the mixture was stirred at 90° C. for about 2 hours to dissolve. This solution was cooled to 40° C., and 100 g of hydrochloric acid having a concentration of 35% by weight and 180 g of formaldehyde were added to carry out an acetalization reaction to precipitate a reaction product.
• polyvinyl formal resin polyvinyl formal resin
• the resulting polyvinyl formal resin was dissolved in DMSO-d 6 at a concentration of 10% by weight, and acetal group content (formalization degree), hydroxyl group content, and acetyl group content were measured using 13 C-NMR.
• Preparation of intermediate base material [prepreg] 6 parts by weight of a curing agent (dicyandiamide) and 10 parts by weight of the resulting polyvinyl acetal resin were added to 100 parts by weight of a bisphenol A type epoxy resin (JER828, manufactured by Japan Epoxy Resin Co., Ltd.), and a process homogenizer (manufactured by SMT) was added. was mixed at 15000 rpm to prepare a resin composition. After that, the obtained resin composition is impregnated into PAN-based carbon fiber (T700SC-12000-50C manufactured by Toray Industries, Inc., number of filaments: 12000, fineness: 800 tex, density: 1.8 g/cm 3 ) by a hand lay-up method. and cured by heating at 110° C. for 1 hour to prepare a prepreg.
• PAN-based carbon fiber T700SC-12000-50C manufactured by Toray Industries, Inc., number of filaments: 12000, fineness: 800 tex, density: 1.8 g/
• prepreg was cured at 180° C. and 0.3 MPa (pressure) for 3 hours using an autoclave (A3675, manufactured by Ashida Seisakusho Co., Ltd.) to produce a molded body.
• Examples 2, 6-10, 17, 18, 21-23, Comparative Examples 1-7, 9 A polyvinyl acetal resin, an intermediate base material (prepreg), and a molded body were produced in the same manner as in Example 1 except that the types and amounts of polyvinyl alcohol resin (PVA) and aldehyde shown in Table 1 were used. In Example 7 and Comparative Example 5, two different aldehydes were used. Further, in Examples 17 and 18 and Comparative Examples 5 and 7, bisphenol F type epoxy resin (NPEF-170, manufactured by Nana Plastic Co., Ltd.) was used instead of bisphenol A type epoxy resin (JER828, manufactured by Japan Epoxy Resin Co., Ltd.). Using.
• Example 3 A prepreg was produced in the same manner as in Example 2, and the obtained prepreg was pressed at 180 ° C. and 10 MPa (pressure) using a press machine (manufactured by Techno Marushichi Co., Ltd., composite material press MB-0 type). A compact was produced by pressing for 10 minutes.
• Example 4 A polyvinyl acetal resin was prepared in the same manner as in Example 2, and 6 parts by weight of a curing agent (dicyandiamide) was added to 100 parts by weight of a bisphenol A type epoxy resin (JER828, manufactured by Japan Epoxy Resin Co., Ltd.) and the resulting polyvinyl acetal. 10 parts by weight of resin was added and mixed at 15000 rpm using a process homogenizer (manufactured by SMT) to prepare a resin composition. Chopped fibers obtained by cutting carbon fibers (T700S-12000 manufactured by Toray Industries, Inc.) into 2.5 mm pieces were randomly dispersed to obtain a discontinuous carbon fiber nonwoven fabric.
• a curing agent dicyandiamide
• a discontinuous carbon fiber nonwoven fabric was impregnated with the obtained resin composition and heated at 80° C. for 3 hours to prepare an intermediate base material [sheet molding compound (SMC)].
• SMC sheet molding compound
• the obtained SMC was pressurized at 180° C. and 10 MPa (pressure) for 10 minutes using a press machine (manufactured by Techno Marushichi Co., Ltd., composite material press machine MB-0) to prepare a molded body.
• Example 5 A polyvinyl acetal resin was prepared in the same manner as in Example 2, and 6 parts by weight of a curing agent (dicyandiamide) was added to 100 parts by weight of a bisphenol A type epoxy resin (JER828, manufactured by Japan Epoxy Resin Co., Ltd.) and the resulting polyvinyl acetal. 10 parts by weight of resin was added and mixed at 15000 rpm using a process homogenizer (manufactured by SMT) to prepare a resin composition.
• a curing agent dicyandiamide
• Example 11 (Production of carboxylic acid-modified polyvinyl acetal resin) 100 g of carboxylic acid-modified polyvinyl alcohol resin was added to 1000 g of pure water and stirred at a temperature of 90° C. for about 2 hours to dissolve. The solution was cooled to 40° C. and 90 g of hydrochloric acid (35% by weight concentration) and 90 g of acetaldehyde were added to the solution. The liquid temperature was lowered to 10° C., and the acetalization reaction was carried out while maintaining this temperature. Thereafter, the mixture was held at 40° C.
• the carboxylic acid-modified polyvinyl alcohol resin is a structural unit having a carboxyl group represented by formula (4-1) (in formula (4-1), R 2 is a single bond, R 3 is a methylene group, X 1 , X 2 is a hydrogen atom), the average degree of polymerization is 400, the degree of saponification is 99.0 mol%, and the amount of acid-modified groups is 0.7 mol%.
• An intermediate substrate (prepreg) and a molded article were produced in the same manner as in Example 1, except that the obtained carboxylic acid-modified polyvinyl acetal resin was used.
• Example 12 As a carboxylic acid-modified polyvinyl alcohol resin, a structural unit having a carboxyl group represented by formula (4-1) (in formula (4-1), R 2 is a single bond, R 3 is a methylene group, X 1 , X 2 is a hydrogen atom), the average degree of polymerization is 400, the degree of saponification is 99.0 mol%, and the amount of acid-modified groups is 2.0 mol%.
• An acid-modified polyvinyl acetal resin, an intermediate base material (prepreg), and a molded body were produced.
• Example 13 As a carboxylic acid-modified polyvinyl alcohol resin, a structural unit having a carboxyl group represented by formula (4-1) (in formula (4-1), R 2 is a single bond, R 3 is a methylene group, X 1 , X 2 is a hydrogen atom), the average degree of polymerization is 600, the degree of saponification is 99.0 mol%, the amount of acid-modified groups is 1.0 mol%, and the amount of acetaldehyde added is 110 g.
• a carboxylic acid-modified polyvinyl acetal resin, an intermediate substrate (prepreg), and a molded article were produced.
• Example 14 (Production of sulfonic acid-modified polyvinyl acetal resin) 100 g of sulfonic acid-modified polyvinyl alcohol resin was added to 1000 g of pure water and stirred at a temperature of 90° C. for about 2 hours to dissolve. The solution was cooled to 40° C. and 90 g of hydrochloric acid (35% by weight concentration) and 90 g of acetaldehyde were added to the solution. The liquid temperature was lowered to 10° C., and the acetalization reaction was carried out while maintaining this temperature. Thereafter, the mixture was held at 40° C.
• the sulfonic acid-modified polyvinyl alcohol resin has a structure in which sulfonic acid groups are directly bonded to carbon atoms in the main chain, and has an average degree of polymerization of 300, a degree of saponification of 99.0 mol %, and an amount of acid-modified groups of 0.5. 7 mol %.
• An intermediate substrate (prepreg) and a molded article were produced in the same manner as in Example 1, except that the obtained sulfonic acid-modified polyvinyl acetal resin was used.
• Example 15 In “(Preparation of intermediate base material [prepreg])", 10 parts by weight of phenoxy resin (Phenotote YP-50, manufactured by Nippon Steel Chemical & Materials Co., Ltd.) is added instead of 10 parts by weight of the obtained polyvinyl acetal resin.
• phenoxy resin Phenotote YP-50, manufactured by Nippon Steel Chemical & Materials Co., Ltd.
• An intermediate base material (prepreg) and a molded body were produced in the same manner as in Example 1, except for the above.
• Example 16 In “(Preparation of intermediate base material [prepreg])", instead of 10 parts by weight of the polyvinyl acetal resin obtained, 10 parts by weight of polyethersulfone (Sumika Excel 5003MPS, manufactured by Sumitomo Chemical Co., Ltd.) was added. In the same manner as in Example 1, an intermediate substrate (prepreg) and a compact were produced.
• Example 20 Except for using phenol novolac type epoxy resin (N-740, manufactured by DIC Corporation) instead of bisphenol A type epoxy resin (JER828, manufactured by Japan Epoxy Resin Co., Ltd.) in "(Preparation of intermediate base material [prepreg])" prepared an intermediate substrate (prepreg) and a molded body in the same manner as in Example 2.
• phenol novolac type epoxy resin N-740, manufactured by DIC Corporation
• bisphenol A type epoxy resin JER828, manufactured by Japan Epoxy Resin Co., Ltd.
• Tg glass transition temperature
• Adhesion interfacial shear strength measurement
• Resin compositions containing polyvinyl acetal resins (or other resins) obtained in Examples and Comparative Examples were dropped on carbon fibers and cured by heating at 150° C. for 1 hour to prepare measurement samples. .
• the interfacial shear strength between the carbon fiber and the resin of the prepared sample was measured by the microdroplet method (drawing speed: 0.12 mm/min) using a composite material interface property evaluation device (manufactured by Toei Sangyo Co., Ltd., model HM410).
• Tackiness The tackiness of the obtained intermediate substrate was evaluated according to the following criteria based on the tactile sensation. ⁇ : Appropriate tackiness and excellent handleability ⁇ : Slightly excessive or insufficient tackiness, but no problem in handling ⁇ : Excessive or significantly insufficient tackiness, handling problem be
• the obtained compact was cut out and its cross section was observed with an optical microscope and SEM.
• the ratio of void area per unit area was calculated and evaluated according to the following criteria. ⁇ : The void generation rate was less than 1% ⁇ : The void generation rate was 1% or more and less than 3% ⁇ : The void generation rate was 3% or more
• a carbon fiber reinforced composite material having excellent tackiness, compatibility with epoxy resin and interfacial adhesion, realizing high mechanical strength and reducing the void generation rate, and carbon A method for manufacturing a fiber-reinforced composite material can be provided.

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