JPH0995599A - Epoxy resin composition, and prepreg and molded product produced using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fibrous reinforcement-contg. epoxy resin compsn. capable of giving a molded product high in interlaminar shear strength and impact strength. SOLUTION: The resin compsn. for molding comprises (A) an epoxy resin; (B) copolymer resin particles obtd. by adding metal cations to core/shell copolymer particles composed of (a) a core portion of a polymer having a glass transition point of at most -30 deg.C and (b) a shell layer consisting of a copolymer of an acrylic ester or methacrylic ester monomer and an unsatd. carboxylic acid monomer having a glass transition point of at least 70 deg.C to effect ion crosslinking thereof, (C) an epoxy resin-curing agent, and (D) a fibrous reinforcement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition, and more particularly to a fiber reinforced epoxy resin composition which gives a molded article having improved interlaminar shear strength and impact strength.

[0002]

2. Description of the Related Art Epoxy resins are widely used as cast molding materials having good operability. However, since the molded product had the disadvantage of low interlaminar shear strength and impact resistance, various modification methods based on fibrous reinforcement were investigated for applications such as fishing rods and skateboards that are subject to bending and impact forces. Came. For example, a method of compounding a liquid acrylonitrile-butadiene rubber containing a terminal carboxyl group has been carried out, but the bending strength is lowered and the impact strength is not sufficiently improved. Further, an epoxy resin composition containing a crosslinked rubbery polymer and fibers has been proposed (JP-A-5-3.
(Japanese Patent No. 39472), the bending strength did not decrease so much, and the impact strength was improved to some extent. However, in order to use a laminated molded product having a large thickness for applications in which bending or impact force is applied, it has been required to further drastically improve the interlaminar shear strength and the impact resistance strength.

[0003]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of providing an epoxy resin composition which can provide a molded product having high interlaminar shear strength and impact resistance.

[0004]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that a core portion having a low glass transition point and a shell layer having a high glass transition point are formed, and It has been found that an epoxy resin composition prepared by combining an ionically crosslinked copolymer resin powder and a fibrous reinforcing material remarkably increases impact resistance strength and extremely high delamination strength of a laminated molded product. The present invention has been completed based on this finding. That is, the present invention comprises: (1) a core portion made of (A) epoxy resin, (B) (a) polymer having a glass transition point of -30 ° C or lower, and (b) acrylic acid ester-based or methacrylic acid ester-based monomer. A metal cation is added to a core / shell type copolymer particle composed of a shell layer made of a copolymer having a glass transition point of 70 ° C. or more between a monomer and an unsaturated carboxylic acid monomer to cause ionic crosslinking. An epoxy resin composition for molding, which comprises the above-mentioned copolymer resin particles, (C) a curing agent for an epoxy resin, and (D) a fibrous reinforcing material. (2) 100 parts by weight of (A) epoxy resin, (B)
The glass transition point of (a) a core portion made of a polymer having a glass transition point of −30 ° C. or lower and (b) an acrylic acid ester-based or methacrylic acid ester-based monomer and an unsaturated carboxylic acid monomer is 70 ° C. Copolymer resin particles obtained by ion-crosslinking a core / shell type copolymer particle composed of the above-mentioned copolymer by adding a metal cation to the core / shell type copolymer particle
Epoxy resin composition for molding, containing 3 to 100 parts by weight of (C) curing agent for epoxy resin (3 to 100 parts by weight) and 20 to 150 parts by weight of (D) fibrous reinforcing material, (3) above (1) or above. (2) Molded product obtained by heat-molding the molding epoxy resin composition, (4) Sheet-shaped product obtained by pseudo-curing by heating the molding epoxy resin composition according to (1) or (2) above (5) A molded product obtained by stacking a plurality of sheet-like prepregs obtained by pseudo-curing by heating the epoxy resin composition for molding according to (1) or (2) above, followed by heat curing, Is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin (A) used in the present invention is an epoxy resin which is liquid or paste at room temperature, and contains bisphenol condensate, hydantoin-based epoxy resin, novolac type epoxy resin, aliphatic epoxy resin, It includes a wide variety of epoxy resins such as dimer acid modified epoxy resin, NBR modified epoxy resin, urethane modified epoxy resin and the like. Examples of particularly preferable epoxy resins include initial condensates obtained by reacting bisphenol A or bisphenol F with an epoxy group-containing compound such as epichlorohydrin. Also, an epoxy resin derived from a compound obtained by adding 2 to 20 mol of ethylene oxide or propylene oxide to bisphenol A can be used.

In the present invention, the core / shell type copolymer resin particles used as the component (B) have a glass transition point of −.
It is a core / shell type copolymer composed of a core portion composed of a polymer at 30 ° C. or lower and a shell layer having a glass transition point of 70 ° C. or higher. The glass transition point of the core portion is −30 ° C. or lower, preferably −40 ° C. or lower. The reason is that when the glass transition point of the core portion is higher than −30 ° C., the function of the resin particles (B) as a reinforcing material for the epoxy resin (A) is lowered, and especially the impact resistance is lowered. . Examples of the monomer that gives a polymer having a glass transition point of −30 ° C. or less include (meth) acrylate-based polymers, diene-based polymers and silicone rubber-based polymers. In the present invention, (meth) acrylate means acrylate or methacrylate. In the core part, a homopolymer is polymerized by using a monomer that gives a glass transition point of -30 ° C or lower, or a monomer mixture containing the monomer as a main component. Examples of the (meth) acrylate-based monomer that gives a homopolymer having a glass transition point of −30 ° C. or lower include n-propyl acrylate (glass transition point of homopolymer −52 ° C.) and n-butyl acrylate (the same). -54
° C), n-octyl acrylate (-65 ° C), 2-
Examples thereof include ethylhexyl acrylate (at -85 ° C) and n-decyl methacrylate (at -65 ° C). Particularly, n-butyl acrylate and 2-ethylhexyl acrylate are preferable. Examples of the diene-based monomer that gives a homopolymer having a glass transition point of −30 ° C. or lower include butadiene, isoprene, 1,3-pentadiene,
Conjugated diene compounds such as cyclopentadiene; 1,4
-Non-conjugated diene compounds such as hexadiene may be mentioned, and these may be used alone or in combination of two or more. Among these, butadiene and isoprene are particularly preferable.

In the present invention, it is also effective to optionally add a crosslinkable monomer to the (meth) acrylate-based or diene-based monomer to form a core portion having more rubber elasticity. . As a crosslinkable monomer for this,
Those having two or more double bonds having substantially the same reactivity, for example, ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) ) Acrylate, hexanediol di (meth) acrylate, oligoethylenedi (meth) acrylate and other (meth) acrylates; aromatic divinyl monomers such as divinylbenzene; triallyl trimellitate and triallyl isocyanurate it can. These crosslinkable monomers may be used alone in the range where the glass transition point of the obtained polymer is −30 ° C. or lower, or may be used in combination of two or more kinds,
Also, the amount used, based on the total weight of the monomer of the core part,
Usually 0.01 to 5% by weight, preferably 0.1 to 2% by weight
It is selected in the range of. When the amount of the crosslinkable monomer used exceeds 5% by weight based on the total weight of the core part, the core part is remarkably crosslinked, and the strength of the epoxy resin composition, especially the impact resistance is lowered.

In addition to the (meth) acrylate-based monomer, diene-based monomer, crosslinkable monomer and the like, other copolymerizable monomers may be used if desired. Examples of the other copolymerizable monomer used as desired include aromatic vinyl compounds such as styrene, vinyltoluene and α-methylstyrene; cyanation such as (meth) acrylonitrile and vinylidene cyanide. Vinyl compounds; 2-hydroxyethyl fumarate, hydroxybutyl vinyl ether, monobutyl maleate, glycidyl methacrylate, butoxyethyl methacrylate and the like can be mentioned. These may be used singly or in combination of two or more, and the amount to be used needs to be selected within a range in which the glass transition point of the polymer of the obtained core part is −30 ° C. or lower. Is usually selected in the range of 50% by weight or less based on the total weight of the monomers in the core part.

As a raw material component of the shell layer (b) comprising a copolymer of (meth) acrylate and unsaturated carboxylic acid having a glass transition point of 70 ° C. or higher, a homopolymer has a glass transition point of 70 ° C. or higher. It is necessary to mainly use the given monomer. Specifically, for example, isopropyl methacrylate (homopolymer glass transition point 81 ° C.), t-butyl methacrylate (the same 107 ° C.), cyclohexyl methacrylate (the same 76 ° C.), phenyl methacrylate (the same 110 ° C.).
(Meth) acrylate monomers such as methyl methacrylate (105 ° C.) and the like. Add to this styrene (at 100 ° C) and 4-chlorostyrene (at 110 ° C).
A), aromatic vinyl monomers such as 2-ethylstyrene (103 ° C.); acrylonitrile (125 ° C. same), vinyl chloride (80 ° C. same), etc. may be used together by 1/4 or less on a weight basis. . Methyl methacrylate is particularly preferable as the main monomer of the shell layer. In the present invention, the glass transition point of the shell layer (b) is 70 ° C or higher, preferably 90 ° C.
℃ or above. When the glass transition point of the shell layer is lower than 70 ° C., the resin particles composed of the core / shell type copolymer are likely to aggregate and form a lump.

In the present invention, for the purpose of ionic crosslinking,
As a raw material component of the shell layer, a radical polymerizable unsaturated carboxylic acid monomer having 3 to 8 carbon atoms is introduced. Examples of such unsaturated carboxylic acid include, for example,
Unsaturated monocarboxylic acids such as (meth) acrylic acid, α-ethylacrylic acid and crotonic acid; unsaturated polycarboxylic acids such as maleic acid, itaconic acid, fumaric acid, citraconic acid, chloromaleic acid and their anhydrides; maleic acid Acid monomethyl, maleate monoethyl, maleate monobutyl,
Unsaturated polycarboxylic acid partial esters having at least one carboxyl group such as monomethyl fumarate, monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, monobutyl itaconate and the like can be mentioned. These may be used alone or in combination of two or more. Among these, in particular (meth) acrylic acid,
Maleic acid or maleic anhydride are preferred. In the present invention, the shell layer copolymer has a carboxyl group-containing monomer unit of 0.01 per 100 parts by weight of the copolymer.
-20 parts by weight, preferably 0.05-10 parts by weight, more preferably 0.1-5 parts by weight. The copolymer 10 has a content of a monomer unit containing a carboxyl group.
When the amount is less than 0.01 parts by weight per 0 parts by weight, the improvement effect of the particle surface modification by ionic crosslinking is hardly exhibited. When the content of the monomer unit containing a carboxyl group exceeds 20 parts by weight per 100 parts by weight of the copolymer, no improvement in the effect of modifying the particle surface is observed for the amount, and rather the core / shell is The original mechanical properties of the type copolymer are degraded. In the present invention, if desired, a crosslinkable monomer may be used in combination as a raw material component of the shell layer. As the crosslinkable monomer, one kind or two or more kinds can be selected and used from the crosslinkable monomers exemplified in the description of the monomer for the polymer forming the core part. The amount of the crosslinkable monomer used is usually 0.01 to 1% by weight, preferably 0.1 to 1% by weight, based on the total weight of the monomers in the shell layer.
It is selected in the range of 0.5% by weight.

In the present invention, the weight ratio of the core portion / shell layer is in the range of 1/4 to 3/1, preferably 1/3 to 2/1. If the weight ratio of the core portion / shell layer is less than 1/4, the impact resistance of the molded product may be reduced. When the weight ratio of the core portion / shell layer exceeds 3/1, the viscosity of the mixture of the ionically crosslinked resin particles of the core / shell type copolymer and the epoxy resin may be increased during storage. . In the present invention, the core / shell copolymer resin particles (B) have good compatibility with the shell layer and the epoxy resin, and therefore have good dispersibility in the epoxy resin. for that reason,
It is possible to isolate and disperse the rubbery core portion, which is incompatible with the epoxy resin, where it will be aggregated and scattered in the matrix if there is no shell layer. Moreover, since the shell layer has a good compatibility with the epoxy resin, the molded article obtained by the composition of the present invention has a high resistance to delamination even when laminated and molded into a thick article.

Generally, when polymer particles having a high compatibility with the dispersion medium are dispersed in the dispersion medium, the dispersion medium penetrates into the particles over time, and the viscosity of the system increases. Therefore, when the resin particles having the shell layer are dispersed in a liquid epoxy resin, the epoxy resin permeates the particles during storage before curing to cause a remarkable increase in viscosity, which makes it difficult to process. In this case, the storage stability can be improved by cross-linking the shell layer by a covalent bond, but conversely, the shock resistance, which is the original purpose, is lowered, which is a contradictory result. By ion-crosslinking the above polymer, it is possible to prevent an increase in viscosity during storage. Ion cross-linking differs from cross-linking structure by covalent bond such as sulfur cross-linking and peroxide cross-linking, and the formation of the cross-linking structure changes thermoreversibly.Therefore, the surface of resin particles modified by ionic cross-linking is On the other hand, under the molding conditions of heat curing, the cross-linking is relaxed. That is, in the present invention, the metal cation as a cross-linking agent forms an ionic cross-link between the carboxyl group and the carboxyl group introduced as a side chain into the shell layer of the core / shell type copolymer, and thereby the tertiary The original polymer structure reduces the swelling property at room temperature due to the epoxy resin as the dispersion medium. However, since the epoxy resin penetrates into the core / shell type copolymer by heating and cures, an epoxy resin molded product in which the rubber component is evenly dispersed in a uniform matrix is formed, so a molded product with great impact resistance. Is obtained. In addition, since a molded product obtained by laminating these layers has good interlaminar fusion, the interlaminar shear strength is large. The component (B) of the present invention has good solvent resistance at room temperature by being subjected to ionic crosslinking treatment, so that methyl ethyl ketone (MEK) or tetrahydrofuran (THF) can be used.
It becomes difficult to dissolve or swell in an organic solvent such as. In the present invention, when the components (A), (B) and (C) and (D) are mixed, it is possible to dilute the mixture with MEK or THF for the purpose of decreasing the viscosity.

In order to produce the core / shell type copolymer used in the present invention, for example, the above-mentioned monomer for forming the core portion is first used, and the polymer particles are polymerized by emulsion polymerization or fine suspension polymerization. Produce a latex. Then, the monomer for forming the above-mentioned shell layer is added to this latex and the polymerization is continued. For this second-stage reaction, an emulsion polymerization method is usually adopted. At that time, in order to obtain a stable reaction product,
A method in which an emulsifier solution or a radical initiator solution is added little by little over a certain period of emulsion polymerization reaction is favored. In order to produce the ion-crosslinked core / shell type copolymer used in the present invention, the above-mentioned carboxyl group-containing monomer is usually added to the above-mentioned monomer for forming the shell layer in the subsequent stage. Include a fixed amount. The copolymer may have a carboxyl group in the entire shell layer, or may have a large number of carboxyl groups at the outermost part of the shell layer.
To form a copolymer containing a large number of carboxyl groups at the outermost part of the shell layer, a method of continuously or intermittently adding a carboxyl group-containing monomer at a later stage of the polymerization reaction of the shell layer, and a component of the shell layer There is a method in which polymer particles prepared by polymerizing a (meth) acrylate-based monomer are saponified with alkali or the like after the polymerization. To prevent the deterioration of the physical properties of the core / shell type copolymer by reducing the proportion of the monomer unit having a carboxyl group in the whole particle by the method of allowing the carboxyl group to exist only on the outermost part of the shell layer. Is preferred. This core / shell type copolymer can be obtained by a multistage polymerization method of at least two stages as described above, but in some cases, the seed latex prepared in the first stage may be prepared with an inorganic salt, alcohol or monomer. It may be produced by partially aggregating and then graft polymerizing it.

Next, a metal cation is added to the core / shell type copolymer to ionically crosslink the carboxyl groups of the shell layer. As the metal cation, for example, monovalent metal ions such as potassium, sodium, lithium, and cesium; divalent metal ions such as calcium, zinc, tin, chromium, and lead can be used. Monovalent or divalent ions of metals belonging to Group I or II of the table are preferred. The cation supplier includes oxides of the above metals; hydroxides; salts of inorganic acids such as phosphates, carbonates, nitrates, sulfates, chlorides, nitrites, and sulfites; Organic acid salts such as formic acid, acetic acid, propionic acid, butyric acid, octylic acid, capric acid, palmitic acid, stearic acid, oleic acid, erucic acid, linolenic acid, succinic acid, adipic acid, naphthenic acid and thiocarboxylic acid; acetylacetone salt And alcoholates such as ethoxide and methoxide. In the case of an acid salt, it is desirable that the acid dissociation constant pK _a is 4 or more. Among these metal cation suppliers, monovalent metal hydroxides and carboxylates are particularly effective in terms of the reaction efficiency of ionic crosslinking and the mechanical strength of the heat-formed product. The monovalent and divalent cations are characterized in that they can undergo an ionic crosslinking reaction within a few minutes at room temperature in a solution.

In the present invention, a core / shell type copolymer having a carboxyl group is used in the method for obtaining the above-mentioned ionically crosslinked resin particles, and the core / shell type after the above-mentioned (1) polymerization step is used. A method of adding a cation supplier to the copolymer latex, (2) a method of dissolving the core / shell copolymer in an appropriate solvent and adding the cation supplier to the polymer solution, (3) an unreacted epoxy There is a method of adding a cation supplier in the process of adding and mixing powder of the core / shell type copolymer to the resin. Although any of these methods can be used, the latex addition method (1) is particularly useful in view of handleability and dispersion efficiency. In the present invention, when the carboxyl group-containing monomer is copolymerized in the aqueous polymerization medium, most of the carboxyl groups are accumulated on the surface layer of the core / shell type copolymer particles due to its hydrophilicity. Therefore, when a cation supplier is added to the aqueous phase, the probability of encountering a cation dissociated in the aqueous phase with a highly dissociative carboxyl group is extremely high, and
Since the reaction is between ions, the ionic crosslinking reaction is completed in a short time. In the present invention, in the above-mentioned ionic crosslinking, a part or all of the carboxyl groups are ionized to form a carboxyl anion, and the ionic crosslinking rate is the amount of the cation donor to be added in order to form an ionic bond by using the metal ion as a counter cation. Can be easily adjusted by. The above-mentioned ionic crosslinking reaction generally proceeds quantitatively, but an excess of the theoretical amount of the cation donor can be used. The presence of this ionic cross-link can be easily analyzed by measuring the absorption of the carboxylate group by infrared absorption spectrum, quantifying the metal ion, and measuring the swelling degree of the core / shell type copolymer in a solvent. It is possible. The dissociation property of ionic crosslinks can be confirmed by differential thermal analysis. In the present invention, when the core / shell type copolymer is ionically crosslinked, the number of moles of the metal atom of the cation donor per carboxyl group contained in the core / shell type copolymer depends on the desired degree of crosslinking. You need to choose a ratio. The amount of the cation donor added is preferably in the range of 0.1 to 3 times the amount of the carboxyl groups in the core / shell type copolymer, and the resin particles ionically crosslinked at this molar ratio have particularly good mechanical properties. Will be excellent. If the molar ratio is less than 0.1 times, the surface modification effect for improving the storage stability of the mixture of the copolymer resin powder and the epoxy resin is significantly inferior, and the molar ratio exceeds 3 times. In this case, the obtained ion-crosslinked resin powder has a high hygroscopic property, and the mechanical properties of the cured product tend to deteriorate.

Powdered resin particles are obtained by spray-drying the ion-crosslinked core / shell type copolymer latex, usually in a multi-blade rotary disc type, a disc type rotary disc type, a nozzle type or the like. To be In the case of this drying, the core / shell type copolymer generally aggregates in units of spray droplets,
Aggregated particles of about 20 to 100 μm are formed. The degree of aggregation depends on the drying conditions, and a step of crushing and loosening after drying can be provided. It is also possible to obtain latex particles in the form of agglomerated particles by coagulating and separating the latex particles by emulsion salting method or freezing method after emulsion polymerization and drying to prepare a wet cake which is dried in a fluidized bed or the like. The amount of the resin particles (B) used in the present invention is 10 to 40 parts by weight, preferably 15 to 30 parts by weight, per 100 parts by weight of the epoxy resin (A). When the amount of the resin particles used is less than 10 parts by weight per 100 parts by weight of the epoxy resin, the bending strength and impact strength of the obtained composition are small, and the amount of the resin particles used exceeds 40 parts by weight per 100 parts by weight of the epoxy resin. If so, the viscosity of the composition becomes high, and the bending strength and impact strength do not increase for the amount used.

In the present invention, examples of the curing agent for epoxy resin used as the component (C) include dicyandiamide; 4,4'-diaminodiphenylsulfone; 2-
Imidazole derivatives such as n-heptadecylimidazole; isophthalic dihydrazide; N, N-dialkylurea derivatives; N, N-dialkylthiourea derivatives; acid anhydrides such as tetrahydrophthalic anhydride; isophoronediamine, m-phenylenediamine , Ethylenediamine,
Polyamines such as hexamethylenediamine, m-xylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine; bis (aminomethyl) cyclohexane, N-aminoethylpiperazine,
Aminoalkyl cyclic compounds such as trisdimethylaminomethylphenol, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro (5,5) undecane; melamine; boron trifluoride complex Compounds include polyamidoamines formed from adducts of various dimer acids and diamines. These may be used alone, or 2
You may use it in combination of two or more kinds, but among these,
Particularly, dicyandiamide is preferable. The compounding amount of the curing agent as the component (C) is not particularly limited, but is usually 3 to 100 parts by weight of the epoxy resin as the component (A).
The proportion is 100 parts by weight, preferably 5 to 85 parts by weight. If this amount is less than 3 parts by weight, curing failure will occur,
If the amount exceeds 100 parts by weight, each strength is remarkably reduced, and an excessive exothermic reaction at the time of molding causes partial decomposition or thermal deterioration, resulting in a marked decrease in each strength or discoloration. When the component (C) is heated to 50 to 200 ° C., it has a function of causing a crosslinking reaction with the epoxy group of the epoxy resin to cure the composition.

As the fibrous reinforcing material used as the component (D) in the present invention, glass fibers made of E glass, C glass, S glass, D glass, fused quartz or chemically treated high silica glass; polyacrylonitrile type, rayon -Based, pitch-based or lignin-poval-based carbon fibers; alumina, beryllium oxide, boron carbide, silicon carbide, silicon nitride, chromium, copper, iron or nickel whiskers; boron-tungsten, boron-fused quartz, titanium boride Alternatively, boron fibers made of boron carbide-boron-tungsten; polyamide fibers (Kevlar fibers); high-temperature resistant nylon fibers (Nomex fibers); thermoplastic fibers made of polyester, polypropylene, vinylon or polyacrylonitrile, and the like. (D)
The form of the fibrous reinforcing material of the component may be any of cloth, strand, roving, mat, roving cloth and the like. The mixing ratio of the fibrous reinforcing material (D) in the present invention is 20 per 100 parts by volume of the epoxy resin (A).
To 100 parts by volume, preferably 40 to 80 parts by volume.
If it is less than 20 parts by volume, the flexural strength and impact strength may not be sufficiently improved. If the amount is more than 100 parts by volume, a large amount of unevenly distributed fiber reinforcing materials are generated, and various strength defects are likely to occur.

In the present invention, if necessary, silica,
Fillers such as calcium carbonate, talc, clay, gypsum, kaolin, mica and kaolin; coupling agents such as organic silane compounds and organic titanate compounds; pigments; flame retardants;
Antiaging agents; diluents and the like can be added.

In preparing the composition of the present invention, usually, a step of first mixing the respective components excluding the fibrous reinforcing material in advance and then impregnating this mixture into the mat-like fibrous reinforcing material is taken. The method of previously mixing the respective components excluding the fibrous reinforcing material is arbitrary, and for example, a kneader such as a disper, a kneader, a triple roll, a paddle mixer or a planetary mixer can be used. By the way, if the epoxy resin is mixed with core / shell resin particles of impact modifier,
It is known that pseudo-curing, which immobilizes in a gel state, occurs by heating above a certain temperature lower than the thermosetting temperature (JP-A-2-80483 and JP-A-6-172).
734). The epoxy resin composition of the present invention is 80
By heating to ℃ or more, it is possible to instantly pseudo-cure. This pseudo-cured product does not fluidize or show tackiness even when reheated at a temperature of 100 ° C. or lower. The composition of the present invention generally comprises the above (A), (B),
The mixture composed of (C) is impregnated into the mat-like fibrous reinforcing material of the component (D) and then preheated to a temperature of 80 to 100 ° C. to obtain a so-called prepreg of a pseudo-cured product. In this way, it is easy to form a molded product by stacking these. That is, after stacking the sheets of the pseudo-cured material so that the target thickness is obtained, the temperature of 120 to 2
A cured molded article can be obtained by heating to 00 ° C. In particular, the composition of the present invention has the property that the core / shell copolymer resin particles are uniformly dispersed in the matrix as described above, so that a molded product obtained by laminating a pseudo-curing sheet and heat curing has good fusion between layers. Thus, the interlaminar shear strength is remarkably improved.

The aspects of the present invention are listed below. (1) (A) Epoxy resin, (B) (a) Core portion made of polymer having glass transition point of -30 ° C or lower, (b) Acrylic ester-based or methacrylic acid ester-based monomer, and unsaturated carvone. Copolymer resin particles obtained by ion-crosslinking by adding a metal cation to core / shell type copolymer particles composed of a shell layer made of a copolymer having a glass transition point of 70 ° C. or more with an acid monomer. A molding epoxy resin composition containing (C) a curing agent for an epoxy resin and (D) a fibrous reinforcing material. (2) 100 parts by weight of (A) epoxy resin, (B)
The glass transition point of (a) a core portion made of a polymer having a glass transition point of −30 ° C. or lower and (b) an acrylic acid ester-based or methacrylic acid ester-based monomer and an unsaturated carboxylic acid monomer is 70 ° C. Copolymer resin particles obtained by ion-crosslinking a core / shell type copolymer particle composed of the above-mentioned copolymer by adding a metal cation to the core / shell type copolymer particle
An epoxy resin composition for molding which comprises 3 to 100 parts by weight of (C) a curing agent for epoxy resin and (D) 20 to 150 parts by weight of a fibrous reinforcing material. (3) (a) The polymer having a glass transition point of −30 ° C. or lower is a diene polymer, an acrylate polymer, a methacrylate polymer or silicon rubber (1) or (2) a molding epoxy resin composition .

(4) The weight ratio of the core portion and the shell layer is 1/4.
The epoxy resin composition for molding according to any one of (1) to (3) above, which is ˜3 / 1. (5) The epoxy resin composition for molding according to any one of (1) to (4) above, wherein the content of the unsaturated carboxylic acid monomer unit is 0.01 to 20 parts by weight per 100 parts by weight of the shell layer copolymer. Stuff. (6) The epoxy resin composition for molding according to any of (1) to (5) above, wherein the unsaturated carboxylic acid monomer is acrylic acid, methacrylic acid, maleic acid or maleic anhydride. (7) The epoxy resin composition for molding according to any one of the above (1) to (6), wherein the addition amount of the metal cation is 0.1 to 3 times the molar amount of the carboxyl group. (8) The epoxy resin composition for molding according to any of (1) to (7) above, wherein the fibrous reinforcing material is glass fiber or carbon fiber. (9) A molded article obtained by heating and curing the molding epoxy resin composition according to any one of (1) to (8). (10) A molded product obtained by laminating a sheet-like prepreg made of the molding epoxy resin composition according to any one of (1) to (8) above in a molding die and curing by heating.

[0023]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Examples 1 to 4 and Comparative Examples 1 to 4 The compounding components in the quantitative ratios shown in Table 1 excluding the fibrous reinforcing material were mixed in a planetary mixer at room temperature for 15 minutes. The mixture is then diluted with methyl ethyl ketone (MEK) and diluted to 3
Adjust the viscosity to less than 00 centipoise (cps) and
It was impregnated with a carbon fiber cloth or a glass fiber cloth having a width of 0 cm and placed on a polyethylene terephthalate (PET) release film. After standing overnight, MEK was removed by vacuum drying at 40 ° C. for 3 hours. Then this is PET
While being placed on the release film, it was heat-treated in a 90 ° C. hot air circulation type oven to form a sheet-like prepreg with a thickness of about 0.3 mm. A prepreg property, a bending test, an interlaminar shear strength, an impact test and the like were performed by the following test methods. Table 1 shows the results
Shown in

(Prepreg property) At the time of forming the prepreg, 9
When heating was performed at 0 ° C and tackiness was lost due to pseudo-curing, the time was taken as the non-tacking time. Next, when the release film made of PET was peeled off, the case where the epoxy resin composition was peeled off without remaining on the film was regarded as good release film peelability. However, when it was not pseudo-cured by heating at 90 ° C, it was not evaluated. Both sides of the obtained prepreg were sandwiched with a PET release film and stored in a thermostatic chamber at 23 ° C. The time until the gel prepreg lost its flexibility was defined as the storage stability time. (Bending Test) Both sides of the prepreg laminated by adjusting the thickness were sandwiched from the contact surface side in the order of the porous release film, the bleeder cloth and the PET release film. 120
Preheat at ℃ × 5kg / cm ² for 10 minutes and then at 180 ℃ 3
Press molding was performed for 0 minutes to obtain a sheet having a thickness of 2 mm. The fiber content was adjusted to the same amount based on the number of laminated sheets and the amount of resin transferred to the bleeder cloth depending on the pressing speed. The pressed sheet is cut with a diamond blade and the surface is surface treated to 2 x 1
A test sample of 5 × 100 mm was obtained. The test sample was stored in a thermostatic chamber at a temperature of 23 ° C. and a humidity of 50% for 2 hours, and then under the same environment, Autograaf AG- was used as a test device.
25 TE type tensile tester (Shimadzu) is used in combination with a cage bending tester equipped with an additional jig, and the crosshead moving speed is 5 mm / min. JIS K 7078
(Carbon fiber reinforced plastic) or JIS K 7
074 (glass fiber reinforced plastic) was used to measure the bending strength and the bending elastic modulus 5 times each to obtain an average value.

(Interlayer Shear Test) A press sheet having a thickness of 2 mm was prepared in the same manner as the bending test sample, and 2 × 10 5 was prepared.
A test sample of x14 mm was obtained, and the temperature was 23 ° C and the humidity was 50.
% Thermostatic chamber for 2 hours. Under the same environment, the autograph AG-25TE type tensile tester (Shimadzu Corporation) was used as a tester with a cage bending tester equipped with an additional jig, and the crosshead moving speed was set to 2 mm / min.
IS K 7078 (carbon fiber reinforced plastic)
Alternatively, the interlaminar shear strength was measured five times and averaged according to JIS K 7074 (glass fiber reinforced plastic). (Impact test) Male / male fitting type metal having a cavity flat surface of 10 × 80 mm open in two directions in the same shape as the open mold described in JIS K 7072 (carbon fiber reinforced plastic) or JIS K 7074 (glass fiber reinforced plastic). Using a 2mm thick spacer in the mold, 10
Laminated prepregs cut into × 80 mm are placed in a cavity, preheated to 120 ° C, and then gradually pressurized to 5 kg / c.
When it reached m ² , press molding was performed at 180 ° C. for 30 minutes. After cooling and demolding, only the edges were surface-treated with a diamond polisher to prepare a test sample of 2 × 10 × 80 mm without a notch. 2 at the temperature of 23 ℃ and humidity of 50%
It was stored for a time, and using a Charpy impact strength tester (manufactured by Toyo Seiki Co., Ltd.) as a test device, a hammer lifting angle of 150
The impact absorption energy was calculated in degrees and converted to impact strength. It measured 5 times and calculated | required the average value. (Glass transition temperature) A differential scanning calorimeter DSC220 (manufactured by Seiko Denshi Kogyo Co., Ltd.) was obtained by taking a sample of about 10 mg from a press sheet prepared for bending test while containing fibers.
Was measured at a heating rate of 10 ° C./min.

[0026]

[Table 1]

Note * 1 Epicoat 828: Bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd. * 2 Core / shell polymer: n-butyl acrylate /
From a core having a glass transition point of -45 ° C. composed of triallyl trimellitate = 47 / 0.5, and methyl methacrylate / methacrylic acid / tetraethylene glycol dimethacrylate = 47/5 / 0.5 (percentages are parts by weight). Particle having an average particle size of 0.3 μm obtained by adding 2 parts by weight of potassium hydroxide to a latex immediately after the polymerization reaction and drying the latex * 3 CTBN1300 × 8 terminal carboxyl-modified acrylonitrile- Butadiene rubber, manufactured by Ube Industries, Ltd. * 4 Zeon F301: Particles having an average particle size of 2 μm made of an epoxy group-containing methyl methacrylate-based copolymer, manufactured by Nippon Zeon Co., Ltd. * 5 Carbon fiber cloth: Torayca T300-3000
(Plain weave), thickness 0.25 mm, manufactured by Toray Industries, Inc. * 6 Glass fiber cloth: Glass cloth WF (plain weave), thickness 0.25 mm, manufactured by Nitto Boseki Co., Ltd.

Regarding the prepreg property, Examples 1 to 4 and Comparative Example 3 in which the core / shell particles or the methyl methacrylate type copolymer particles according to the present invention were blended were simulated in a gel form within 1 minute by heating at 90 ° C. Although cured, examples of addition of terminal carboxyl-modified acrylonitrile-butadiene rubber (Comparative Example 2) and examples of no addition of polymer (Comparative Examples 1 and 4)
Then, the epoxy resin composition became a highly viscous liquid and was difficult to handle for molding. Examples 1 to 4
The prepreg of Comparative Example 3 exhibited a good release film peeling property, and was stable for a long period of time at a stable storage time of 6 months or more. In terms of flexural strength and flexural modulus, when carbon fibers are added, Examples 1 to 3 in which core / shell particles are added are almost the same as Comparative Example 1 in which core / shell particles are not added. Even when glass fiber is added, the same thing can be seen in Example 3 and Comparative Example 4. Impact resistance and interlaminar shear strength are
The superiority and inferiority clearly appeared with or without the addition of core / shell particles. The glass transition temperature can be slightly lowered by adding core / shell particles, but the terminal carboxyl-modified acrylonitrile-
With the addition of butadiene rubber (Comparative Example 2), a significant decrease is seen. From these tests, by adding the core / shell particles according to the present invention, the epoxy resin composition containing the fibrous reinforcing material has a prepreg having stable handleability, impact resistance and particularly interlayer shear strength are remarkable. It can be seen that it provides improved molded products.

[0029]

EFFECTS OF THE INVENTION The composition of the present invention makes it possible to obtain a prepreg which is easy to handle and an epoxy resin molded article having high impact resistance and high interlaminar shear strength.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C08K 7/02 NLD C08K 7/02 NLD C08L 51/04 LLB C08L 51/04 LLB

Claims (5)

[Claims] 1. A core portion comprising (A) an epoxy resin, (B) (a) a polymer having a glass transition point of −30 ° C. or less, and (b) an acrylic ester-based or methacrylic ester-based monomer. Copolymer obtained by ion-crosslinking by adding a metal cation to core / shell type copolymer particles composed of a shell layer composed of a copolymer having a glass transition point of 70 ° C. or higher with a saturated carboxylic acid monomer. A molding epoxy resin composition comprising resin particles, (C) a curing agent for an epoxy resin, and (D) a fibrous reinforcing material. 2. (A) Epoxy resin 100 parts by weight,
(B) Glass transition point of (a) core part made of polymer having glass transition temperature of -30 ° C or lower, and (b) acrylic acid ester-based or methacrylic acid ester-based monomer and unsaturated carboxylic acid monomer Copolymer resin particles obtained by ion-crosslinking a core / shell type copolymer particle composed of a shell layer of a copolymer having a temperature of 70 ° C. or higher with a metal cation.
To 40 parts by weight, (C) curing agent for epoxy resin 3 to 10
An epoxy resin composition for molding comprising 0 part by weight and 20 to 150 parts by weight of (D) a fibrous reinforcing material. 3. A molded product obtained by heating and curing the molding epoxy resin composition according to claim 1. 4. A sheet-like prepreg obtained by preheating the epoxy resin composition for molding according to claim 1 or 2. 5. A molded product obtained by stacking a plurality of sheet-like prepregs obtained by preheating the molding epoxy resin composition according to claim 1 or 2 and heating and curing. Epoxy resin cast molded product obtained by stacking and compressing in a mold.