JP2019112483A - Carbonate resin composition for carbon fiber-reinforced composite material, prepreg and carbon fiber-reinforced composite material - Google Patents

Abstract

To provide a carbonate resin composition having excellent curability and storage stability, a prepreg for carbon fiber-reinforced composite material excellent handling property, and a carbon fiber-reinforced composite material which is suitable applications of a structure material of an automobile, an aircraft, etc. and a housing of an electric/electronic apparatus, and the like, and is excellent in mechanical strength and adhesion.SOLUTION: There are provided a carbonate resin composition for carbon fiber-reinforced composite material containing a carbonate resin having at least two carbonate groups in the molecule and an amine-based curing agent as essential components, a prepreg formed by impregnating a carbon fiber with the carbonate resin composition, and a carbon fiber-reinforced composite material obtained by heating and curing the prepreg.SELECTED DRAWING: None

Description

  The present invention relates to a carbonate resin composition for carbon fiber reinforced composite material suitable as a matrix resin of carbon fiber reinforced composite material. More specifically, the present invention relates to a fiber reinforced composite material comprising a carbon fiber reinforced composite material carbonate resin composition capable of providing a carbon fiber reinforced composite material excellent in curability, storage stability, mechanical properties and adhesion and a carbon fiber.

  Fiber reinforced composites with epoxy resin and other thermosetting resins as matrix resin, especially carbon fiber reinforced composites using carbon fibers, are structural materials such as aircraft and vehicles due to their light weight and excellent mechanical properties, concrete It is used in a wide range of fields, including structures, golf clubs, and sports fields such as fishing rods. Such a carbon fiber reinforced composite material is often obtained by laminating a prepreg obtained by impregnating a thermosetting resin into a reinforcing fiber.

  The various properties required of the prepreg used for the above applications include excellent storage stability and excellent curability, in addition to the excellent physical properties of molded articles such as mechanical properties and adhesion. In particular, when using a mold for forming a prepreg, the curing speed is important. If the curing time of the prepreg is halved, the production amount can be doubled, and the productivity is improved.

  With respect to such required characteristics, a technique using dicyandiamide as a curing agent and DCMU (3,4-dichlorophenyl-1,1-dimethylurea) as a curing accelerator is disclosed as a rapid curing technique for an epoxy resin composition (Patent Document 1). However, although this composition is excellent in curability, there is a problem in storage stability because the reaction of epoxy proceeds with the heat history of the process of kneading the resin and impregnating the carbon fiber.

  On the other hand, it is known that a five-membered ring carbonate resin, which is one of thermosetting resins, selectively reacts with amines to open a ring, thereby giving a urethane derivative having a hydroxyl group, as a paint and an adhesive. It is considered as a base resin applicable to materials such as.

  The method for producing the urethane derivative is obtained by using a five-membered ring carbonate as a raw material and carbon dioxide as a raw material of the five-membered ring carbonate. Therefore, it becomes resin in which carbon dioxide was taken in in the structure. This means that this is a technology that should be focused on from another viewpoint of technology that contributes to greenhouse gas reduction, which has become a problem in recent years.

  Therefore, various five-membered ring carbonates are studied from the above background. Patent Document 2 discloses, as one application example of five-membered ring carbonate, a carbonate monomer having at least two five-membered ring carbonate groups in one molecule, and a primary amino group and a secondary amino group selected in one molecule. An example is shown in which a mixture with an amine monomer having at least two amino groups is subjected to a polymerization reaction to produce a polyhydroxyurethane resin. The example which manufactures a polyhydroxy urethane resin by making it react with diamine is described using bisphenol A carbonate resin and 1, 6- hexanediol type | mold carbonate resin as bifunctional five-membered-ring carbonate. However, no detailed study was given on the physical properties of the resulting polyhydroxyurethane.

  On the other hand, Patent Document 3 shows an example of a resin composition based on a combined use system of an epoxy resin and a five-membered ring carbonate resin, and an application example as a paint is shown. An example focusing on is not shown.

  Moreover, although the synthesis example of a phenol novolak-type carbonate resin and the physical-property example of hardened | cured material are shown by patent document 4 as polyfunctional five-membered-ring carbonate, the examination example which paid its attention to complexation with carbon fiber here also. Is not disclosed.

Special re-publication 2005-82982 gazette Japanese Patent Application Publication No. 2006-9001 Patent No. 5581435 gazette JP, 2016-180049, A

  An object of the present invention is to provide a carbonate resin composition having excellent curability and storage stability in a carbon fiber reinforced composite material, a prepreg for a carbon fiber reinforced composite material having excellent handleability, and mechanical strength, It is providing the carbon fiber reinforced composite material which is excellent in adhesiveness.

  That is, the present invention is a carbonate resin composition for a carbon fiber reinforced composite material comprising a carbonate resin having at least two carbonate groups in the molecule and an amine curing agent as essential components.

  The above-mentioned carbonate resin has an epoxy equivalent of 100 to 300 g / eq. It is preferable that it is carbonate resin obtained by carbonate-izing the epoxy resin of this, and that melt viscosity in 150 degreeC is 0.01-10.0 Pa.s.

（Ｒ_１は、水素又は炭素数１〜６の炭化水素基を示し、ｎは１〜２０の数を示す。）

（Ｒ_１、Ｒ_２は、水素又は炭素数１〜６の炭化水素基を示し、Ａは、-C(CH₃)₂-、-CH₂-、-O-、-S-、-SO₂-、または単結合であり、ｍは０から１０の数を示す。）

（ここで、Ｒ_３は、酸素原子で連結されても、水酸基を有していてもよい脂肪族炭化水素基を示しｌは２〜３の数を示す。）
一般式（１）、（２）及び（３）において、Ｘは下記式（ａ）で表される基である。

As said carbonate resin, resin represented by following General formula (1), (2) or (3) is mentioned.

(R ₁ represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and n represents a number of 1 to 20.)

(R ₁ and R _{2 each} represent hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and A represents —C (CH ₃ ) ₂ —, —CH ₂ —, —O—, —S— or —SO ₂ -Or a single bond, m represents a number of 0 to 10.)

(Here, R ₃ represents an aliphatic hydrocarbon group which may be linked by an oxygen atom or may have a hydroxyl group, and l represents a number of 2 to _3. )
In the general formulas (1), (2) and (3), X is a group represented by the following formula (a).

  As the above-mentioned amine curing agent component, aliphatic amines are preferably mentioned.

  The present invention is also a prepreg for carbon fiber reinforced composite material, which is obtained by impregnating the above-mentioned carbonate resin composition into carbon fiber.

  Furthermore, the present invention is a carbon fiber reinforced composite material obtained by heat curing the above-mentioned prepreg.

  The carbonate resin composition for a carbon fiber reinforced composite material according to the present invention is excellent in curability and storage stability when applied to a carbon fiber reinforced composite material, and gives a prepreg excellent in handleability and also in mechanical properties and adhesion. It is possible to provide an excellent carbon fiber reinforced composite material and to be suitably used for applications such as structural materials such as automobiles and aircrafts, and casings of electric and electronic devices.

GPC chart of carbonate resin A GPC chart of carbonate resin B GPC chart of carbonate resin C GPC chart of carbonate resin D

The carbonate resin composition for a carbon fiber reinforced composite material of the present invention will be described. Hereinafter, the carbonate resin composition for a carbon fiber reinforced composite material is also referred to as a carbonate resin composition or a resin composition.
First, the carbonate resin used for the carbonate resin composition of the present invention will be described.
The carbonate resin can be obtained by reacting an epoxy resin with carbon dioxide.

  Although the epoxy resin used for said carbonation reaction has 2 or more of epoxy groups in 1 molecule, as the epoxy equivalent, 100-300 g / eq. Those in the range of are preferred. If it is higher than this range, the functional group density of the obtained carbonate resin is lowered and the curability is lowered. On the other hand, if it is lower than this range, although the curability is improved, the storage stability when used as a prepreg is reduced.

  As a method of reacting carbon dioxide with epoxy resin, a method of reacting at a temperature of 40 to 200 ° C. in the presence of a catalyst such as an alkali metal can be mentioned.

  Under the present circumstances, it is good to react substantially all the epoxy groups of an epoxy resin, using carbon dioxide 1 mol or more, preferably large excess, preferably with respect to 1 mol of epoxy groups as a ratio of an epoxy resin and carbon dioxide. However, when it is intended to blend the epoxy resin into the resin composition, the amount of carbon dioxide may be such that a part of the unreacted epoxy resin remains.

  The melt viscosity at 150 ° C. of the carbonate resin used in the present invention is preferably in the range of 0.01 to 10.0 Pa · s. When the melt viscosity is higher than this range, when molding a carbon fiber reinforced composite material using a prepreg, the resin does not sufficiently flow to the surface, which causes a problem that the smoothness of the molded product is impaired. On the other hand, when the viscosity is lower than this range, the smoothness of the surface of the molded product is improved, but the resin is leaked from the mold due to the decrease in viscosity, and a desired molded product can not be obtained. It becomes. The melt viscosity is preferably as low as possible in the above range.

  The softening point of the carbonate resin is preferably 40 to 150 ° C, preferably in the range of 50 to 100 ° C. Here, the softening point refers to the softening point measured based on the ring and ball method of JIS-K-2207. If it is lower than this range, the heat resistance of the cured product will decrease when the carbonate resin composition is cured, and if it is higher than this range, the flowability at the time of molding and the impregnatability to carbon fibers will decrease.

  The carbonate resin used in the present invention is one having at least two carbonate groups in the molecule. This carbonate group is a five-membered ring group in the above formula (a). The carbonate resin composition of the present invention may contain any type of carbonate resin, but the carbonate resin represented by any of the general formulas (1) to (3) is suitably used.

  The carbonate resin represented by the general formula (1) is selected from carbonate resins carbonated on the basis of a polyfunctional epoxy resin containing an aromatic structure having two or more epoxy groups in one molecule. Examples of multifunctional epoxy resins include epoxidized products such as phenol novolac and o-cresol novolac. Among them, a carbonate resin obtained from a novolac epoxy compound such as phenol novolac or cresol novolac can improve mechanical strength and heat resistance due to the effect of increasing the crosslink density, so it is preferable to use it more preferably. it can.

  Other preferable carbonate resins not included in the general formula (1) include trivalent or higher trivalent compounds such as tris- (4-hydroxyphenyl) methane and 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane. Epoxy compounds of phenols, epoxy compounds of co-condensed resin of dicyclopentadiene and phenols, epoxy compounds of phenolaralkyl resins synthesized from phenols and paraxylylene dichloride, etc., synthesized from phenols and bischloromethylbiphenyl, etc. And carbonate resins obtained from epoxidates of naphthol aralkyl resins synthesized from naphthols, paraxylylene dichloride, etc., and the like.

  In General formula (1), n shows the number of 1-20, Preferably, it is the range of 1.5-10.0 on average. If this is too large, the molecular weight of the resin is increased, and the resin flowability at the time of molding is reduced, so that there is a problem that the smoothness of the molded body is reduced.

  The carbonate resin represented by the general formula (2) is selected from carbonate resins carbonated on the basis of a bifunctional epoxy resin containing an aromatic structure having two epoxy groups in one molecule. As a bifunctional epoxy resin, for example, bisphenol A, bisphenol F, 3,3 ′, 5,5′-tetramethyl-bisphenol F, bisphenol S, dihydroxydiphenyl sulfide, dihydroxydiphenyl ether, biphenol, 3,3 ′, 5 And epoxidized products of difunctional dihydroxy compounds such as 5'-tetramethyl-4,4'-dihydroxybiphenol. Among them, bisphenol A and bisphenol F type carbonate resins can be more preferably used from the viewpoint of improving adhesion and mechanical strength.

In General formula (2), although m shows the number of 0-10, Preferably, it is the range of 0-5 on average. If this is too large, as in the case of the general formula (1), the molecular weight of the resin is increased, and the functional group density is reduced, so that the curability is lowered. In the general formula (2), A is —C (CH ₃ ) ₂ —, —CH ₂ —, —O—, —S—, —SO ₂ — or a single bond.
In the general formulas (1) and (2), R ₁ and R _{2 each} represent hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, preferably hydrogen or methyl.

The carbonate resin represented by the general formula (3) is selected from carbonate resins carbonated based on an aliphatic epoxy resin having two or more epoxy groups in one molecule. In the general formula (3), R ₃ represents an aliphatic hydrocarbon group, but may contain an ether-type oxygen atom in the chain, specifically a hydrocarbon group in the range of 2 to 15 carbon atoms, _{- (C 2 H 4 O)} b -, - (C 3 H 6 O) b -, more can be hydroxyl groups in these groups are those which are introduced as a substituent. Here, b represents a number of 1 to 20. l represents a number of 2 to 3.
If the number of carbon atoms is too large, the molecular weight of the resin increases and the resin flowability at the time of molding decreases, which causes a problem that the smoothness of the formed product is reduced.
For example, as specific compounds, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, Carbonate resins based on aliphatic epoxy compounds such as 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, hydrogenated bisphenol A diglycidyl ether and the like can be mentioned. Among them, ethylene glycol and trimethylolpropane type carbonate resin can be more preferably used from the viewpoint of improvement of moldability and adhesion.

  In the general formulas (1), (2) and (3), X is a group represented by the above formula (a) and is a carbonate group-containing group.

  Next, the method for producing the carbonate resin used in the present invention will be described.

  The reaction for obtaining a carbonate resin from an epoxy resin and carbon dioxide can be carried out in the presence of a catalyst, and the amount of the catalyst is in the range of 1 to 20 wt%, preferably in the range of 1 to 10 wt%. When the amount is more than this range, the generated carbonate resin itself tends to increase the molecular weight by the polymerization reaction, and lowers the low viscosity. On the other hand, if the amount is less than this range, the reactivity decreases and a large amount of unreacted epoxy resin is left. Moreover, the amount of catalyst as used herein means the amount of catalyst with respect to the weight of the epoxy resin used for the reaction.

  As this catalyst, for example, salts such as lithium chloride, lithium bromide, lithium iodide, sodium chloride, sodium bromide, sodium iodide and the like, and quaternary ammonium salts are mentioned as preferable. In addition, triphenylphosphine or the like may be simultaneously used to improve the solubility of salts serving as catalysts.

  Moreover, the reaction temperature in this reaction is performed in 40-200 degreeC. If it is lower than this, the reactivity decreases and the reaction time becomes long. Also, if it is higher than this, the carbonate bond is likely to be partially cleaved, and the curability and heat resistance are reduced.

  This reaction is usually performed for 1 to 20 hours. Furthermore, during the reaction, polar solvents such as N-methylpyrrolidone, dimethylformamide, dimethylsulfoxide and dimethylacetamide, alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol, methyl cellosolve and ethyl cellosolve, and acetone Ketones such as methyl ethyl ketone and methyl isobutyl ketone, ethers such as dimethyl ether, diethyl ether, diisopropyl ether, tetrahydrofuran and dioxane, and aromatic compounds such as benzene, toluene, chlorobenzene and dichlorobenzene can be used as the solvent.

  As a specific method for carrying out this reaction, all the raw materials other than carbon dioxide are charged at one time and reacted under a carbon dioxide atmosphere or while bubbling carbon dioxide at a predetermined temperature, or charging an epoxy resin and a solvent Generally, the reaction is performed while intermittently adding the catalyst while maintaining the temperature at a predetermined temperature. After the reaction, when a solvent is used, if necessary, after removing the catalyst component, the solvent can be distilled off to obtain the resin of the present invention, and when the solvent is not used, direct discharge by heat The objective carbonate resin can be obtained. This carbonate resin has a structure in which an epoxy group is a carbonate group.

  Next, the amine-based curing agent used for the carbonate resin composition of the present invention will be described.

  The compounding amount of the curing agent is blended in consideration of the equivalent balance of the carbonate group of the carbonate resin and the amino group in the amine curing agent. The equivalent ratio of the carbonate resin and the curing agent is usually in the range of 0.2 to 5.0, preferably in the range of 0.5 to 2.0. When the size is larger or smaller than this range, the curability of the carbonate resin composition is reduced, and the heat resistance, the mechanical strength, and the like of the cured product are reduced.

  The compounding amount of the curing agent is usually determined within the range of 2 to 200 parts by weight, preferably 5 to 80 parts by weight, with respect to 100 parts by weight of the carbonate resin. If the amount of the curing agent is out of this range, there is a problem that the moldability and the strength of the cured product are reduced.

As the amine curing agent, aromatic and aliphatic amines and the like can be used, and any conventionally known one can be used. As preferable ones, for example, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, 1,8-diaminooctane, 1,10-diaminodecane, 1,12-diaminododecane , Linear aliphatic amines such as diethylenetriamine and triethylenetetramine, isophoronediamine, norbornanediamine, 1,6-cyclohexanediamine, cyclic aliphatic amines such as piperazine, p-xylylenediamine, o-xylylenediamine and the like Aromatic amines such as aliphatic amines having an aromatic ring, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl sulfone, m-phenylenediamine, 2,5-diaminopyridine and the like Amines are mentioned. Preferably, it is an aliphatic amine.
One or two or more of these amine curing agents can be mixed and used.

  An epoxy resin may be blended in the above composition. The epoxy resin to be used is selected from those having two or more epoxy groups in one molecule. For example, bisphenol A, bisphenol F, 3,3 ', 5,5'-tetramethyl-bisphenol F, bisphenol S, fluorene bisphenol, 2,2'-biphenol, 3,3', 5,5'-tetramethyl- Epoxides of dihydric phenols such as 4,4'-dihydroxybiphenol, resorcin and naphthalenediols, tris- (4-hydroxyphenyl) methane, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane , Epoxides of trivalent or higher phenols such as phenol novolac and o-cresol novolac, epoxidates of co-condensed resin of dicyclopentadiene and phenols, and phenolaralkyl resins synthesized from phenols and paraxylylene dichloride Epoxides, Phenols and Bi The epoxy compound of the biphenylaralkyl type phenol resin synthesize | combined from a chloro methyl biphenyl etc., the epoxy compound of the naphthol aralkyl resin synthesize | combined from naphthols and paraxylylene dichloride etc., etc. are mentioned. These epoxy resins can be used alone or in combination of two or more.

  In the carbonate resin composition of the present invention, an oligomer or polymer compound such as polyester, polyamide, polyimide, polyether, polyurethane, petroleum resin, indene resin, indene cumarone resin, phenoxy resin or the like is used as another modifier or the like. You may mix | blend suitably. The addition amount is usually in the range of 2 to 30 parts by weight with respect to 100 parts by weight of the carbonate resin.

  In addition, additives such as an inorganic filler, a pigment, a flame retardant, a thixotropic agent, a coupling agent, and a flowability improver can be blended in the carbonate resin composition of the present invention. Examples of the inorganic filler include spherical or crushed fused silica, silica powder such as crystalline silica, alumina powder, glass powder, mica, talc, calcium carbonate, alumina, hydrated alumina and the like.

  Examples of the pigment include organic or inorganic extender pigments and scale-like pigments. Examples of the thixotropic agent include silicones, castor oils, aliphatic amide waxes, oxidized polyethylene waxes, organic bentonites, and the like.

  Furthermore, in the carbonate resin composition of the present invention, a curing accelerator such as a base catalyst and a Lewis acid catalyst can be used as needed. For example, tertiary amines such as triethylamine, tributylamine, DBU (diazabicycloundecene), DABCO (diazabicyclooctane), pyridine and the like; lithium chloride, lithium bromide, lithium fluoride, alkali such as sodium chloride Metal salts; alkaline earth metal salts such as calcium chloride; quaternary ammonium salts such as tetrabutyl ammonium chloride, tetraethyl ammonium bromide, tetraethyl ammonium iodide, benzyltrimethyl ammonium chloride; carbonates such as potassium carbonate, sodium carbonate; zinc acetate Metal acetates such as lead acetate, copper acetate and iron acetate; metal hydrides such as calcium hydride; metal oxides such as calcium oxide, magnesium oxide and zinc oxide; Phosphonium salts such as Le phosphonium chloride, sulfonium salts such as benzyl tetrahydrothiophenium chloride; and the like. The amount to be added is usually 0.01 to 10 parts by mass with respect to 100 parts by mass in total of the carbonate resin and the amine curing agent.

  Furthermore, as necessary, in the resin composition of the present invention, releasing agents such as carnauba wax and OP wax, coupling agents such as γ-glycidoxypropyltrimethoxysilane, coloring agents such as carbon black, trioxide Flame retardants such as antimony, stress reducing agents such as silicone oil, lubricants such as calcium stearate may be used.

  Furthermore, if necessary, other additives may be added to the resin composition of the present invention. For example, antioxidants (hindered phenols, phosphites, thioethers, etc.), light stabilizers (hindered amines, etc.), UV absorbers (benzophenones, benzotriazoles, etc.), gas discoloration stabilizers (hydrazines, etc.) ), Hydrolysis inhibitors (such as carbodiimides), metal deactivators, etc., and combinations of two or more of these.

  The epoxy resin composition for carbon fiber reinforced composite materials of the present invention can be impregnated with carbon fibers and preferably used as a prepreg. Moreover, the prepreg of the present invention uses carbon fiber as a reinforcing fiber. By using carbon fiber as a reinforcing fiber, it is possible to develop excellent mechanical strength in the fiber-reinforced composite material.

  In the present invention, carbon fibers of all types can be used depending on the application, and carbon fibers having a tensile strength of usually 1.0 GPa to 9.0 GPa are preferably usable. The tensile strength is preferably as high as possible from the viewpoint of high tensile strength of carbon fiber and high impact resistance when it is made into a composite material, and the more preferable tensile strength is 2.0 GPa to 9.0 GPa.

  Carbon fibers used in the present invention include those classified into polyacrylonitrile-based, rayon-based and pitch-based carbon fibers, but a pitch-based carbon fiber excellent in high elasticity is preferable from the viewpoint of good mechanical strength expression. Used.

  In addition to carbon fibers, the carbonate resin composition of the present invention can be impregnated into fibrous materials such as glass cloth, aramid nonwoven fabric, polyester nonwoven fabric such as liquid crystal polymer, and the like. Further, the solvent can be removed to obtain a prepreg. Moreover, it can be set as a laminated body by apply | coating on sheet-like materials, such as copper foil, stainless steel foil, a polyimide film, a polyester film, depending on the case.

  Next, a manufacturing method suitable for obtaining the prepreg of the present invention will be described.

  The prepreg of the present invention is obtained by impregnating the above-mentioned carbonate resin composition into carbon fibers. As a method of impregnating, a wet method of dissolving a carbonate resin composition in a solvent such as methyl ethyl ketone to lower viscosity and impregnating carbon fiber, or a carbonate resin composition is reduced in viscosity by heating without using a solvent to carbon fiber A prepreg can be manufactured by a method such as a hot melt method of impregnating.

  In the present invention, in order to form a carbon fiber reinforced composite material using a prepreg, a method of heating and curing an epoxy resin composition for a carbon fiber reinforced composite material while laminating the prepreg and applying pressure to the laminate, etc. It can be used preferably.

  The carbon fiber reinforced composite material is formed by filament winding forming including an autoclave forming method using a prepreg in which a thermosetting matrix resin is previously impregnated into carbon fibers, a step of impregnating carbon fibers with a liquid matrix resin, and a forming step by thermosetting. It shape | molds by methods, such as a method and the resin transfer molding method. Among them, in the autoclave molding method, after laminating a prepreg in which a resin is impregnated on a carbon fiber in advance, the layers are adhered by pressure reduction and high-quality molded products are obtained by pressing and heating with an autoclave. it can. However, this method has a disadvantage that productivity is low because the pressure reduction step and the curing step by the autoclave are long. Therefore, as a method to improve productivity, a prepreg compression molding method (PCM method) has been developed to obtain a carbon fiber reinforced composite material by molding and curing a resin by heating and pressing a prepreg laminated in advance with a mold. There is.

  In the PCM method, a carbon fiber is pre-impregnated with a thermosetting resin that is thermally cured in a short time to prepare a prepreg, and this prepreg is previously matched to the shape of a molded product to be subjected to pattern cutting, laminating, and preform shaping. Thereafter, the desired carbon fiber reinforced composite material can be obtained by molding the preform at a high pressure and a high temperature for a short time using a high power hydraulic press.

  The various properties required of the prepreg used in the PCM method are, of course, excellent in general mechanical properties, but at the same time the curing time at the curing temperature during molding while being excellent in storage stability in order to facilitate handling. Needs to be short. This is because it is possible to improve the productivity in a limited production facility by shortening the curing time.

  In the PCM method, there is a process of laminating the prepreg at room temperature in the work performed before press molding. In this process, if the tack property (stickiness of the surface) is strong on the prepreg surface, correction in alignment during lamination is performed. Operation becomes difficult. Furthermore, if wrinkles or stacking faults occur due to the prepreg sticking to an unintended part, the product will be defective and the yield will decrease. Therefore, materials with low tackiness are required to improve productivity.

  Further, although the prepreg is impregnated with a resin in the PCM method, a thermosetting resin is used for this resin. With respect to this thermosetting resin, the above-mentioned storage stability and rapid curing properties are required. Furthermore, it is required that the resin viscosity at the time of curing does not decrease too much. This is because the resin viscosity is reduced by the temperature at the time of press molding, and the smoothness of the surface of the molded product is improved. However, when the viscosity reduction time is long, the resin leaks from the mold and a desired molded product can be obtained. It is because it is gone. In addition, if the curing reaction proceeds before the resin viscosity is completely reduced, the resin does not sufficiently flow to the surface, which causes a problem that the smoothness is impaired. Therefore, in order to shorten the curing time, it is important to balance resin viscosity and curing speed.

  As a shaping | molding temperature for obtaining a carbon fiber reinforced composite material, although it is based on the kind etc. of resin contained in carbonate resin composition, the temperature of 80-220 degreeC is preferable normally. If the molding temperature is too low, sufficient rapid curability may not be obtained. On the other hand, if it is too high, warpage due to thermal distortion may easily occur.

  Moreover, as a pressure shape | molded by the press molding method in order to obtain a carbon fiber reinforced composite material, although it changes with thickness of a prepreg etc., the pressure of 0.1-1 Mpa is preferable normally. If the molding pressure is too low, the heat may not be sufficiently transmitted to the inside of the prepreg, and may locally become uncured or warp may occur. On the other hand, if it is too high, the resin may flow out to the periphery before curing and voids may be generated in the carbon fiber reinforced composite material.

  Hereinafter, the present invention will be more specifically described by way of examples.

Synthesis example 1
100 g of bisphenol A type epoxy resin (manufactured by Nippon Steel Sumikin Chemical; YD-128, epoxy equivalent 190 g / eq., Melt viscosity 0.005 ° · s at 150 ° C.) in a 1 L four-necked flask is N-methyl-2-pyrrolidone Dissolve in 200 g, add 4.6 g of lithium bromide, and react at 100 ° C. for 8 hours while blowing in carbon dioxide gas. After the reaction, the reaction solution was added dropwise to 5 L of pure water for reprecipitation, suction filtration, washing with reslurry, and drying under reduced pressure. Then, after dissolving in methyl ethyl ketone and removing the remaining N-methyl-2-pyrrolidone by azeotropy, 119 g of resin was obtained (Carbonate resin A). The melt viscosity of the carbonate resin A at 150 ° C. was 0.64 Pa · s. The GPC chart is shown in FIG.
In all of the synthesis examples, the blowing amount of carbon dioxide gas is a large excess amount with respect to the theoretical amount, and the epoxy group is almost converted to a carbonate group.

Synthesis example 2
A reaction was performed in the same manner as in Synthesis Example 1 except that 100 g of a phenol novolac epoxy resin (epoxy equivalent 174 g / eq., Melt viscosity 0.02 Pa · s at 150 ° C.) was used as the epoxy resin to obtain 110 g resin ( Carbonate resin B). The melt viscosity at 150 ° C. was 4.4 Pa · s. The GPC chart is shown in FIG.

Synthesis example 3
The same reaction as in Synthesis Example 1 was carried out except that 100 g of ethylene glycol type epoxy resin (manufactured by Kyoeisha Chemical Co., Ltd .; Epolite 40E, epoxy equivalent 132 g / eq.) Was used as an epoxy resin, to obtain 102 g of a resin (Carbonate Resin C) . The melt viscosity at 150 ° C. was 0.05 Pa · s. The GPC chart is shown in FIG.

Synthesis example 4
The same reaction as in Synthesis Example 1 except that 100 g of bisphenol A epoxy resin (manufactured by Nippon Steel & Sumikin Chemical; YD-011, epoxy equivalent 475 g / eq., Melt viscosity at 150 ° C. 1.8 Pa · s) was used as the epoxy resin. To obtain 102 g of a resin (Carbonate resin D). The melt viscosity at 150 ° C. was 12.5 Pa · s. The GPC chart is shown in FIG.

The measurement conditions are as follows.
1) Molecular weight distribution of carbonate resin Using a GPC measuring device (HLC-8320GPC, manufactured by Tosoh Corp.), using two TSKgel SuperHZ 2000 (manufactured by Tosoh Corp.) and two TSKgel SuperHZ2500 (manufactured by Tosoh Corp.) as a column, and using RI as a detector. The solvent was measured as tetrahydrofuran, flow rate 0.35 ml / min, column temperature 40 ° C.

2) Melt viscosity Measured at 150 ° C. using a CAP2000H rotational viscometer manufactured by BROOKFIELD.

Examples 1 to 7 and Comparative Example 1
The carbonate resin obtained in Synthesis Example 1 to 4 was used as a carbonate resin component, and a bisphenol A epoxy resin (manufactured by Nippon Steel Sumikin Chemical Co., Ltd .; YD-128) was used as a comparison. Using tris (2-aminoethyl) amine (reagent manufactured by Wako Pure Chemical Industries, curing agent A), metaxylene diamine (reagent manufactured by Sigma Aldrich, curing agent B) as a curing agent, and cyclopentanone as a solvent The compound shown in Table 1 was blended to obtain a carbonate resin composition. Since this carbonate resin composition is in the form of a solution, it is also referred to as a varnish. The numbers indicating the compounding amounts in Table 1 are parts (parts by weight).

  The results of measuring the gel time, viscosity and storage stability of the carbonate resin composition are shown in Table 1.

The measurement conditions are as follows.
3) Gel time The resin composition was added onto a gelation tester (manufactured by Nisshin Scientific Co., Ltd.) plate heated to 150 ° C., and stirred at a speed of 2 revolutions per second using a fluoroplastic rod. The gelation time required for the carbonate resin composition to cure was examined.
4) Varnish viscosity and storage stability The viscosity at 25 ° C. of the resin composition was measured using a TVE-22 viscometer E-type viscometer manufactured by Toki Sangyo Co., Ltd. The storage stability was evaluated by measuring the initial viscosity immediately after compounding and the viscosity one day after leaving it at 5 ° C. for one day, and the viscosity increase rate calculated by the following equation.
Viscosity increase rate (%) = (Viscosity after 1 day-initial viscosity) / initial viscosity x 100

Examples 8 to 14 and Comparative Example 2
A carbonate resin composition shown in Table 2 was obtained in the same manner as in Examples 1 to 7 except that 100 parts of methyl ethyl ketone was used as a solvent. In Table 2, the example number in the resin composition indicates that the composition is the same as that of the example (excluding the solvent).
Using this carbonate resin composition, a carbon fiber (made by Nippon Graphite Fiber; PF-XA 80-240) is impregnated, and then dried with a hot air circulating dryer at 80 ° C. for 3 minutes to remove methyl ethyl ketone and then prepreg. Obtained.
Four layers of this prepreg were laminated and heat cured at 80 ° C. for 1 hour under a pressure of 0.2 MPa. Then, it was further cured at 120 ° C. for 1 hour under the same pressure to obtain a carbon fiber reinforced plastic as a carbon fiber reinforced composite material.
Table 2 shows the evaluation of the tackiness of the prepreg, and the measurement results of the glass transition point, flexural strength and flexural elasticity, and interlayer shear strength of the carbon fiber reinforced plastic.

The measurement conditions are as follows.
5) Evaluation of tackiness The resin composition is placed on the release-treated PET film, a 1 mm thick fluororesin sheet is used as a spacer, and a polyethylene film is placed on the resin as a cover film, and then 4 minutes at 80 ° C. The sample laminated | stacked on PET film-resin composition (1 mm thickness)-polyethylene film was created by pressing. The tackiness evaluation is performed when the prepared sample is allowed to stand in a constant temperature chamber at 23 ° C. for 1 hour and then the polyethylene film is peeled off when the polyethylene film is peeled off. ○, peeling of the polyethylene film is difficult, or a resin composition The case where it remained in the polyethylene film was evaluated as x.

6) Glass transition point (Tg)
The Tg was determined by a Seiko Instruments TMA 7100 thermomechanical measuring device under the conditions of a temperature rising rate of 10 ° C./min.

7) Bending strength and bending elasticity According to JIS K 6911, it measured at normal temperature by the 3 point bending test method.

8) Interlaminar shear strength Measured according to JIS K 7078 at room temperature by the interlaminar shear test method of carbon fiber reinforced plastic. The case without shearing was regarded as 〇.

Claims (7)

  A carbonate resin composition for a carbon fiber reinforced composite material comprising, as an essential component, a carbonate resin having at least two carbonate groups in a molecule and an amine curing agent.   The carbonate resin has an epoxy equivalent of 100 to 300 g / eq. The carbonate resin composition for a carbon fiber reinforced composite material according to claim 1, which is a carbonate resin obtained by carbonating an epoxy resin of   The carbonate resin composition for a carbon fiber reinforced composite material according to claim 1 or 2, wherein the melt viscosity at 150 ° C of the carbonate resin is 0.01 to 10.0 Pa · s. The carbonate resin composition for a carbon fiber reinforced composite material according to any one of claims 1 to 3, wherein the carbonate resin is a resin represented by the following general formula (1), (2) or (3) .

(R ₁ represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and n represents a number of 1 to 20.)

(R ₁ and R _{2 each} represent hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and A represents —C (CH ₃ ) ₂ —, —CH ₂ —, —O—, —S— or —SO ₂ -, Or represents a single bond, m represents a number of 0 to 10.)

(R ₃ is an aliphatic hydrocarbon group which may be linked by an oxygen atom or may have a hydroxyl group, and l is a number of 2 to _3. )
In the general formulas (1), (2) and (3), X is a group represented by the following formula (a).

  The carbonate resin composition for a carbon fiber reinforced composite material according to any one of claims 1 to 4, wherein the amine curing agent component is an aliphatic amine.   A prepreg for carbon fiber reinforced composite material, which is obtained by impregnating carbon fiber reinforced composite material carbonate resin composition according to any one of claims 1 to 5 into carbon fiber. A carbon fiber reinforced composite material obtained by heat curing the prepreg according to claim 6.

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