JPH0741575A - Prepreg and fiber-reinforced composite material - Google Patents

Abstract

PURPOSE:To provide a prepreg which can give a composite material having high impact resistance, high interlaminar toughness and high edge delamination resistance upon stretching a cross laminate as well as high interlaminar shear strength and high heat resistance and to provide a fiber-reinforced composite material obtained therefrom. CONSTITUTION:The prepreg comprises a fibrous reinforcement (A) comprising long fibers, a thermosetting resin composition (B), fine particles (C) insoluble in component B, and fine particles (D) of a resin soluble in component B. Components C and D are localized on the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg used for a structure which is required to have high strength and elastic modulus as advanced composite materials, and further specific strength and specific elastic modulus obtained by dividing these by specific gravity. The present invention relates to a fiber-reinforced composite material that is a molded product.

[0002]

2. Description of the Related Art An advanced composite material is a non-uniform material having reinforcing fibers and a matrix resin as essential constituent elements. Therefore, there is a large difference between the physical properties in the fiber axis direction and the physical properties in the other directions. . For example, it is known that the resistance to drop weight impact does not lead to a drastic improvement even if the strength of the reinforcing fiber is improved. In particular, the composite material using a thermosetting resin as a matrix resin reflects the low toughness of the matrix resin and has insufficient impact resistance. Further, when a tensile load is applied to the cross-laminated plate, delamination often occurs from the plate ends, and thus the degree of freedom in the laminated structure is often limited. Therefore, various methods have been proposed for the purpose of improving physical properties other than the fiber axis direction, particularly impact resistance and interlayer toughness.

As a method of increasing the toughness of the thermosetting resin itself, a method of adding a polysulfone resin to an epoxy resin is disclosed in JP-A-60-243113, and a method of adding an aromatic oligomer to the epoxy resin is special. Kaisho 61-2
It is disclosed in Japanese Patent Publication No. 28016. It is said that the impact resistance of the composite material is improved by increasing the toughness of the resin.

Japanese Laid-Open Patent Publication No. 60-63229 discloses that an epoxy resin film modified with an elastomer is placed between layers of a fiber reinforced prepreg to improve impact resistance.

US Pat. No. 4,604,319 discloses that a thermoplastic resin film is provided between layers of a fiber reinforced prepreg to improve impact resistance.

The present inventors have disclosed US Pat. No. 5,028,47.
No. 8 discloses a matrix resin containing fine particles made of a resin. In particular, by localizing the resin fine particles on the surface of the prepreg, a composite material having improved impact resistance while maintaining the tackiness (adhesiveness) and drapeability (hereinafter, tack drapeability) of the prepreg is provided. I showed that.

US Pat. No. 4,863,787 discloses an epoxy resin, a reactive oligomer and a particle size of 10-7.
It is disclosed that a prepreg using a matrix resin composed of 5 micron elastomeric particles provides a composite material with improved impact resistance. Here, it is stated that a phase separation structure is formed in the cured resin portion other than the elastomer particles.

European Published Patent No. 0377194 A
In the specification of No. 2, the epoxy resin mixed with epoxy-soluble polyimide particles (particle diameter of 2 to 35 μm) partially having a non-aromatic skeleton such as aminophenyltrimethylindane is used as the matrix resin, and the impact resistance of the composite material is improved. It is disclosed that the property is improved. According to the publication, the soluble polyimide particles dissolve in the interlayer portion of the composite material during molding.

Japanese Patent Laid-Open No. 3-26750 discloses that a composite material using epoxy resin, a reactive polysulfone oligomer, and resin fine particles of a reactive elastomer and an epoxy resin as a matrix resin has excellent impact resistance.

[0010]

However, in these methods, the impact resistance improving effect is still insufficient,
Each has its own drawbacks, such as sacrificing interlaminar shear strength, handleability and other properties to improve impact resistance.

When a thermoplastic resin such as high molecular weight polysulfone is mixed to improve the resin toughness as in JP-A-60-243113, the viscosity of the resin composition becomes too high and the reinforcing fiber is impregnated. Becomes difficult and the tack and drape of the prepreg are impaired. JP-A 61-228
Even when an oligomer having a reduced molecular weight is added as in Japanese Patent Publication No. 016, it is necessary to increase the addition amount of the thermoplastic resin sufficiently in order to obtain sufficient resin toughness, and the viscosity of the resin composition increases accordingly. It becomes too difficult to impregnate the reinforcing fiber. Further, as the amount of the thermoplastic resin increases, the solvent resistance of the cured product decreases. Moreover, even if the toughness of these resins themselves is improved, it tends to reach a ceiling for improving the impact resistance of the composite material.

When an independent outer layer film containing an elastomer-modified thermosetting resin is used as in JP-A-60-63229, the interlaminar shear strength and heat resistance decrease as the content of elastomer increases, and If the content of the is small, the impact resistance improving effect is very small.

Further, when a thermoplastic resin film is used as in US Pat. No. 4,604,319, heat resistance and impact resistance are improved by using a thermoplastic resin film having good heat resistance. The effects are compatible with each other to some extent, but the tackiness (adhesiveness) and the drapeability, which are advantages of the thermosetting resin, are lost. Further, the general defect of the thermoplastic resin that the solvent resistance is not good is reflected in the composite material.

When the particles existing in the interlayer portion are elastomers as in US Pat. No. 4,863,787, the interlayer thickness is likely to change due to changes in molding conditions such as pressure and temperature rising rate. In addition, impact resistance is easily affected by molding conditions. Further, it is considered that the presence of the elastomer lowers the interlaminar shear strength and heat resistance of the composite material.

European Published Patent 0377194 A2
Also when disposing a soluble polyimide in the interlayer portion as in the specification, the interlayer thickness is likely to change due to changes in molding conditions, and impact resistance is easily affected by molding conditions.

Since there is no description of post-impact compression strength (CAI) in the examples of JP-A-3-26750, the degree of impact resistance cannot be evaluated. However, particles containing an elastomer have an interlaminar shear strength and heat resistance. It is thought to reduce the sex.

On the other hand, in the US Pat. No. 5,028,478 disclosed by the present inventors, the prior example most similar to the present invention in that the resin fine particles are localized in the interlayer portion of the composite material. Is. CAI is as high as 53.3 ksi in Examples using amorphous transparent nylon fine particles for the purpose of improving impact resistance while maintaining heat resistance.
Interlaminar toughness G in unidirectional composite peeling mode
_{When IC} was measured, it was not much different from the conventional composite using an epoxy resin as a matrix resin. By using thermoplastic resin particles with a low elastic modulus within the scope of the same technology,
Although CAI can be further improved, there is a risk that the heat resistance and the interlaminar shear strength of the composite material will be reduced.

The present invention has impact resistance and interlaminar toughness that exceed those of the preceding examples while maintaining high interlaminar shear strength and heat resistance, and further, plate edge peel strength (EDS) when a cross laminated plate is pulled. It is an object of the present invention to provide a prepreg and a fiber-reinforced composite material obtained from the prepreg for giving a composite material having a significantly high sinter.

[0019]

The prepreg of the present invention has the following constitution in order to achieve the above object. That is, the prepreg comprises the following constituent elements [A], [B], [C] and [D], and the constituent elements [C] and [D] are localized on the surface. [A]: Reinforcing fiber consisting of long fibers [B]: Thermosetting resin composition [C]: Fine particles insoluble in component [B] [D]: Resin soluble in component [B] Further, the fiber-reinforced plastic of the present invention has the following constitution in order to achieve the above object. That is, it consists of the following components [A], [B '], [C'] and [D '],
The fiber-reinforced composite material is characterized in that the constituent elements [C ′] and [D ′] are localized in the laminated interlayer portion. [A]: Reinforcing fiber consisting of long fiber [B ']: Thermosetting resin cured product [C']: Resin fine particle [D ']: Amorphous type distinguishable from constituent elements [B'] and [C '] Resin phase

(Explanation of Component [A]) The component [A] used in the present invention is a reinforcing fiber composed of long fibers. The reinforcing fiber used in the present invention is a fiber generally used as an advanced composite material, which has good heat resistance and tensile strength. For example, the reinforcing fibers include carbon fibers, graphite fibers, aramid fibers, silicon carbide fibers, alumina fibers, boron fibers, tungsten carbide fibers, and glass fibers. Among these, carbon fibers and graphite fibers, which have good specific strength and specific elastic modulus and are recognized to make a great contribution to weight reduction, are the best for the present invention. It is possible to use all kinds of carbon fibers and graphite fibers depending on the application, but high-strength carbon fibers with a tensile elongation of 1.5% or more are suitable for manifesting the strength of the composite material. There is. High strength and high elongation carbon fibers having a tensile strength of 450 kgf / mm ² or more and a tensile elongation of 1.7% or more are more preferable, and the tensile elongation is 1.9.
%, High strength and high elongation carbon fiber is most suitable. In addition, long fiber-shaped reinforcing fibers are used in the present invention, and the length thereof is preferably 5 cm or more. When the length is shorter than that, it becomes difficult to sufficiently develop the strength of the reinforcing fiber as a composite material. Further, the carbon fiber or the graphite fiber may be used as a mixture with other reinforcing fiber. Further, the shape and arrangement of the reinforcing fiber are not particularly limited, and for example, a single direction, a random direction, a sheet shape, a mat shape, a woven shape, or a braided shape can be used. In addition, an array in which reinforcing fibers are aligned in a single direction is most suitable for applications that require high specific strength and high inelastic modulus, but a cloth (fabric) array that is easy to handle. Are also suitable for the present invention.

(Explanation of Component [B]) The component used as the component [B] in the present invention is a thermosetting resin composition. When the thermosetting resin is used as the matrix resin, the fiber-reinforced composite material is more advantageous than the thermoplastic resin itself as the matrix resin in that low-pressure molding by autoclave is possible.

The thermosetting resin which is a component of the constituent element [B] is preferably a resin which is cured by heat or energy from the outside such as light or electron beam to at least partially form a three-dimensional cured product. To be

A specific example of the thermosetting resin suitable for the present invention is an epoxy resin, which is generally used in combination with a curing agent or a curing catalyst. In particular, epoxy resins having an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor are preferable. Specifically, as an epoxy resin using amines as a precursor, tetraglycidyl diaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol,
As an epoxy resin containing various isomers of triglycidylaminocresol and phenols as precursors, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, Examples of the epoxy resin containing a compound having a carbon-carbon double bond as a precursor include alicyclic epoxy resins and the like, but are not limited thereto. Brominated epoxy resins obtained by bromizing these epoxy resins are also used. Epoxy resins having an aromatic amine as a precursor typified by tetraglycidyldiaminodiphenylmethane are most suitable for the present invention because they have good heat resistance and good adhesion to reinforcing fibers.

The epoxy resin is preferably used in combination with an epoxy curing agent. As the epoxy curing agent, essentially any compound can be used as long as it is a compound having an active group capable of reacting with an epoxy group. Known epoxy resin curing agents can be used as appropriate, but in particular, amino groups,
A compound having an acid anhydride group or an azide group is suitable. Specifically, dicyandiamide, various isomers of diaminodiphenyl sulfone, and aminobenzoic acid esters are suitable. More specifically, dicyandiamide is preferred because it is excellent in storage stability of prepreg. Various isomers of diaminodiphenyl sulfone are most suitable for the present invention because they give a cured product having good heat resistance.
As the aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used,
Although it is inferior in heat resistance to diaminodiphenyl sulfone, it is selected and used according to the application because of its excellent tensile elongation.

It is also possible to mix a small amount of inorganic fine particles such as finely powdered silica or an elastomer with the epoxy resin.

As the thermosetting resin in the constituent element [B],
In addition to epoxy resin, maleimide resin, acetylene-terminated resin, nadic acid-terminated resin, cyanate ester-terminated resin, vinyl-terminated resin,
A resin having an allyl terminal is also preferably used. These may be appropriately mixed with an epoxy resin or another resin and used. Further, a reactive diluent may be used, or a modifier such as a thermoplastic resin or an elastomer may be mixed and used to such an extent that heat resistance is not significantly deteriorated.

The maleimide resin is a compound containing an average of two or more maleimide groups per molecule. Bismaleimide prepared from diaminodiphenylmethane is particularly preferably used. Examples of this type of maleimide compound include N, N'-phenylene bismaleimide, N, N'-hexamethylene bismaleimide, N, N'-methylene-di p-phenylene bismaleimide, N, N'-oxy-di-. p-phenylene bismaleimide, N, N'-4,4 '
-Benzophenone bismaleimide, N, N'-diphenylsulfone bismaleimide, N, N '-(3,3'-dimethyl) -methylene-di-p-phenylene bismaleimide, N, N'-4,4 '-Dicyclohexylmethane bismaleimide, N, N'-m (or p) -xylylene-bismaleimide, N, N'-(3,3'-diethyl) -methylene-di-p-phenylene bismaleimide, N, N '
Examples of the reaction product include, but are not limited to, a reaction product of a mixed polyamine, which is a reaction product of aniline and formalin, and a maleic anhydride, such as -metatorylene-di-maleimide and bismaleimide of bis (aminophenoxy) benzene. Further, these maleimide compounds may be used in a mixed system of two or more kinds, and N-allyl maleimide,
N-propylmaleimide, N-hexylmaleimide, N
-It may contain a monomaleimide compound such as phenylmaleimide.

Maleimide resin is a curing agent (reactive diluent)
It is preferably used in combination with. As the curing agent, essentially any compound can be used as long as it is a compound having an active group capable of reacting with a maleimide group. Known curing agents can be used as appropriate, but in particular, compounds having an amino group, an alkenyl group represented by an allyl group, a benzocyclobutene group, an allyl nadic imide group, an isocyanate group, a cyanate group, an epoxy group are suitable. There is. For example,
Diaminodiphenylmethane is a typical curing agent having an amino group, and examples of the curing agent having an alkenyl group include 0,0′-diallylbisphenol A and bis (propenylphenoxy) sulfone.

The bismaleimide-triazine resin (BT resin) composed of the above-mentioned bismaleimide and cyanate ester is also suitable as the thermosetting resin of the present invention. As the resin having a cyanate ester terminal, a cyanate ester compound of polyhydric phenol represented by bisphenol A is suitable. The resin combining cyanate ester resin and bismaleimide resin is available from Mitsubishi Gas Chemical Co., Inc.
It is commercially available as T-resin and is suitable for the present invention. In general, these resins have better heat resistance and water resistance than epoxy resins, but are inferior in toughness and impact resistance, so it is preferable to select and use them according to the application. Bismaleimide and cyanate ester are usually preferably used in a weight ratio of 0/100 to 70/30. The case of 0/100 is a cyanate ester (triazine) resin, but it is characterized by a low water absorption rate, and this is also suitable in the present invention.

Further, a thermosetting polyimide resin having a terminal reactive group is also suitable as the thermosetting resin in the component [B] and the component [B ']. As the terminal reactive group, nadiimide group, acetylene group, benzocyclobutene group and the like are preferable.

The thermosetting resin in the constituent [B] and constituent [B '] is widely recognized in the industry such as phenol resin, resorcinol resin, unsaturated polyester resin, diallyl phthalate resin, urea resin and melamine resin. It is also possible to use a thermosetting resin.

Since the component [B] and the component [B '] are thermosetting resins containing a thermoplastic resin component as a modifier, the resin toughness is improved as compared with the case of the thermosetting resin alone. preferable. The term "thermoplastic resin component" as used herein refers to a thermoplastic resin that has been widely recognized in the industrial world. However, since it does not impair the high heat resistance and high elastic modulus of the thermosetting resin, it is a so-called engineering plastic of aromatic type. Those belonging to the present invention are preferable as the thermoplastic resin. That is,
Thermosetting resin having aromatic polyimide skeleton, aromatic polyamide skeleton, aromatic polyether skeleton, aromatic polysulfone skeleton, aromatic polyketone skeleton, aromatic polyester skeleton, aromatic polycarbonate skeleton soluble in high heat resistant thermoplastic Resins are typical, and specific examples thereof include polyether sulfone, polysulfone, polyimide, polyether imide, and polyimide having a phenyltrimethylindane structure.

As the thermosetting resin-soluble and highly heat-resistant thermoplastic resin, those having an aromatic polyimide skeleton are particularly preferable because they are excellent in heat resistance, solvent resistance and toughness. As these thermoplastic resins, commercially available polymers may be used, or those synthesized appropriately according to the purpose may be used. In addition, it is preferable to use a so-called oligomer having a lower molecular weight than that of a commercially available polymer because the composite material can have high toughness without impairing the handling property of the prepreg.
It is more preferable that these thermoplastic resin components have a functional group capable of reacting with the thermosetting resin at the terminal or in the molecular chain, because they contribute greatly to the improvement of toughness while maintaining the original solvent resistance of the thermosetting resin. An amino group is mentioned as a typical reactive terminal.

As a method for synthesizing an aromatic polyimide which is particularly preferable as the thermoplastic resin added to the constituent element [B] and the constituent element [B '], any known method can be used. It is synthesized by reacting an acid dianhydride with a diamino compound. Preferred examples of the tetracarboxylic dianhydride are pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Dianhydride, 3,3 ', 4,4'-diphenyl ether tetracarboxylic acid dianhydride, 3,3',
Aromatic tetracarboxylic dianhydrides such as 4,4′-diphenylsulfone tetracarboxylic dianhydride, more preferably 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′ , 4,4'-diphenyl ether tetracarboxylic acid dianhydride and the like.

Preferred examples of diamino compounds are diaminodiphenylmethane, metaphenylenediamine, paraphenylenediamine, diaminodiphenyl ether, diaminodiphenylsulfone, diaminodiphenyl sulfide, diaminodiphenylethane, diaminodiphenylpropane, diaminodiphenylketone, diaminodiphenylhexafluoropropane, Diaminodiphenylfluorene, bis (aminophenoxy) benzene, bis (aminophenoxy) diphenylsulfone, bis (aminophenoxy) diphenylpropane, bis (aminophenoxy) diphenylhexafluoropropane, fluorenediamine, dimethyl substitution product of diaminodiphenylmethane,
Aromatic diamino compounds such as tetramethyl-substituted diaminodiphenylmethane, diethyl-substituted diaminodiphenylmethane, tetraethyl-substituted diaminodiphenylmethane, and dimethyldiethyl-substituted diaminodiphenylmethane, more preferably bis (aminophenoxy)
Benzene, bis (aminophenoxy) diphenyl sulfone, bis (aminophenoxy) diphenylpropane,
Bis (aminophenoxy) diphenylhexafluoropropane, diaminodiphenylfluorene, fluorenediamine, dimethyl substitution product of diaminodiphenylmethane,
Aromatic diamino compounds such as tetramethyl-substituted diaminodiphenylmethane, diethyl-substituted diaminodiphenylmethane, tetraethyl-substituted diaminodiphenylmethane, and dimethyldiethyl-substituted diaminodiphenylmethane can be exemplified.

Further, as the thermoplastic resin contained in the constituent element [B] and the constituent element [B '], a block copolymer or a graft copolymer comprising a chain compatible with the thermosetting resin and a chain incompatible with the thermosetting resin. The use of is particularly preferable from the viewpoint of compatibility control.

One of the preferred embodiments is component [B]
The thermosetting resin is a block copolymer or graft copolymer having a chain of siloxane skeleton which is originally incompatible. A typical siloxane chain is a dimethylsiloxane skeleton, but it may contain phenylsiloxane. By having a siloxane chain, the water absorption of the resin can be reduced and the water resistance can be increased.

When the molecule of the thermoplastic resin contained in the constituent element [B] has as a block chain a chain which is originally incompatible with the thermosetting resin component in the constituent element [B], a complete compatibility with the same molecular weight is obtained. Compared with the case of a thermoplastic resin consisting only of chains, the resin viscosity increase due to its addition is small. Therefore, there is little deterioration in workability, and the prepreg using this resin as a matrix resin has the effects of excellent tackiness and drapeability. From another point of view, the restriction on the amount of the thermoplastic resin added in the constituent element [B] is loose, and a large amount can be introduced into the resin system without impairing the tackiness, which is advantageous for improving the resin toughness.

Further, the fact that the portion other than the incompatible chain is a block copolymer having a polyimide skeleton compatible with the thermosetting resin composition as the constituent [B] improves the heat resistance of the resin. preferable.

Component [B] or component [B ']
When a thermoplastic resin is allowed to coexist therein, the amount thereof is 5 to 35 in all the components of the constituent [B] or constituent [B '].
Weight percent is preferred. If it is less than this range, the effect of improving toughness is small, and if it is more than this range, the workability is significantly deteriorated. It is more preferably 8 to 25% by weight.

Here, the thermoplastic resin component in the constituent element [B] may be dissolved in advance in the uncured thermosetting resin component, or may be dispersed and mixed. Also,
It may be partially dissolved and partially dispersed. The viscosity of the resin can be adjusted by changing the dissolution / dispersion ratio, and the tackiness and drapeability of the prepreg can be adjusted to a desired degree. Most of the dispersed thermoplastic resin also dissolves in the thermosetting resin component during the molding process. In order to improve the toughness, it is preferable to phase-separate again by the end of curing to form the above-mentioned appropriate microphase-separated structure.

The molecular weight of the thermoplastic resin in the constituent element [B] is about 2 in terms of number average molecular weight when the thermoplastic resin component is dissolved in the uncured thermosetting resin component in advance.
The range of 000 to 20,000 is preferable. When the molecular weight is smaller than this, the effect of improving toughness is small, and when the molecular weight is larger than this, the resin viscosity is remarkably increased and the workability is markedly reduced. More preferably about 2500-1000
The range is 0. On the other hand, when the thermoplastic resin component in the constituent element [B] is dispersed in the uncured thermosetting resin component without being dissolved, the molecular weight of the thermoplastic resin is preferably up to about 100000, which is a high molecular weight region. .

A thermosetting resin-soluble thermoplastic resin is mixed or dissolved in the constituent element [B], and a phase containing the thermosetting resin as a main component and a thermoplastic resin as a main component during resin curing. It is preferable from the viewpoint of improving the toughness of the composite material that the cured resin [B ′] undergoes microphase separation into the phase to be formed. In particular, the phase-separated structure after curing is a phase separated from a phase containing a thermoplastic resin as a main component and a phase containing a thermosetting resin as a main component, and at least a phase containing a thermoplastic resin as a main component, preferably Is preferably a resin cured product having a microphase-separated structure in which both phases are three-dimensionally continuous, because it provides high toughness. It is more preferable to have a more complicated phase separation morphology in which the continuous phase contains another dispersed phase.

By having a microphase-separated structure in which the phase containing the thermoplastic resin as a main component at least partially forms a continuous phase, a cured resin product having a high elasticity and a high toughness is obtained. As component [B '], 250 kg / m
The fracture strain energy release rate G of at least 200 J / m ² or more, further 250 J / m ² or more while maintaining the bending elastic modulus of m ² or more, further 300 kg / mm ² or more.
It is preferably a high toughness resin cured product having an _IC .

The breaking strain energy release rate G _IC of the cured resin obtained from the composition used in the present invention is measured by the double torsion method (hereinafter DT method). For more information on the DT method, see Journal of Materials Science (J
individual of Materials Science
ce) Vol. 20, pp. 77-84 (1985). G _IC is calculated crack load P, the slope [Delta] C / .DELTA.a _f and crack growth of the sample thickness t for crack extension distance a _f compliance C by the following equation. G _IC = P ² (ΔC / Δa _f ) / 2t Here, the compliance C is C = δ / P depending on the crosshead displacement amount δ when the crack occurs and the crack generating load P.
Is defined by

(Explanation of Constituent Element [C] ([C ']) and [D] ([D'])) The constituent element [C] is a fine particle that does not dissolve in the constituent element [B]. ] Are fine particles made of a resin that can be dissolved in the constituent element [B]. In addition, the constituent element [C ′] is fine resin particles, and the constituent element [D ′] is an amorphous resin phase which can be distinguished from the constituent elements [B ′] and [C ′].

Here, the fine particles which are not dissolved in the constituent element [B] are those which can substantially maintain the fine particle state during molding in the system combined with the constituent element [B], that is, the thermosetting resin in the constituent element [B]. Of the resin that can be substantially maintained before and after curing, and the fine particles made of a resin soluble in the constituent [B] are fine particles during molding in a system combined with the constituent [B]. A state in which the state cannot be substantially maintained, that is, a state in which the fine particle state is substantially changed (into an amorphous phase) before and after the thermosetting resin in the constituent element [B] is cured.

The standard will be described more concretely. When the constituent element [B] is an epoxy resin or a cyanate resin, 5 wt% of fine particles are added to the constituent element [B].
%, And under a condition of 25 ° C. and heating and stirring at 140 ° C. for 2 hours, the microscope is observed under two conditions. In the observation at 25 ° C., the region occupied by the fine particles in the resin (the fine particle area on the micrograph) (Represented by) is 100%, 1
When the area occupied by the fine particles after the heat treatment at 40 ° C. for 2 hours is reduced to 30% or less, the fine particles correspond to “meltable”, while the area occupied by the fine particles remains 90% or more after the heat treatment. If so, the fine particles correspond to "not dissolved". When the constituent [B] is a bismaleimide resin or the like, a reactive diluent is generally used together, but in this case, the liquid component of the constituent [B] including these is also subjected to the same test as above. You can check whether it corresponds to.

The components [C '] and [D'] are present in the fiber-reinforced composite material obtained by laminating and curing the prepreg containing the components [C] and [D], respectively. ] And [D]. At that time, the constituent elements [C ′] and [D ′] do not necessarily have to have the same shape as the original [C] and [D], and in particular, the constituent element [D ′] is being molded by the constituent element [D]. Once the original form has been lost, the component [B '],
It exists as an amorphous resin phase that can be distinguished from [C ′].

The fine particles of the constituent elements [C] and [D] have the following advantages. That is, since the fine particles are present in a state of being dispersed in the matrix resin when mixed with the matrix resin which is the constituent [B], the tackiness and drapability of the matrix resin are reflected as the prepreg characteristics, A prepreg with excellent properties.

As described in the section of the prior art, in US Pat. No. 5,028,478, which has been already disclosed by the present inventors, a technique for localizing resin fine particles in an interlayer portion of a composite material. Is shown. In order to improve the impact resistance while maintaining the heat resistance, the examples using fine particles of amorphous transparent nylon have a high CAI of 53.3 ksi.
However, when the peeling mode interlaminar toughness G _IC of the unidirectional composite was measured, it was not much different from the conventional composite using the epoxy resin as the matrix resin. CAI can be further improved by using thermoplastic resin fine particles having a low elastic modulus within the scope of the same technology, but the interlayer shear strength and heat resistance of the composite material may be reduced. That is, impact resistance, interlaminar toughness, interlaminar shear strength, and heat resistance of composite materials have hitherto been contradictory properties.

That is, when only the constituent element [C] ([C ']) is used, the amount of particles added to give high impact resistance, interlaminar toughness and plate edge peel strength increases, and the prepreg of There is a tendency that the handling property and the manufacturing process property are deteriorated, and the compressive strength of the composite material, particularly the compressive strength at high temperature and the interlaminar shear strength tend to be impaired.

On the other hand, when only the constituent element [D] ([D ']) is used, the effect of improving impact resistance, interlaminar toughness and plate edge peel strength is small, and their physical properties are influenced by molding conditions. Have a tendency to be greatly affected.

However, by using the constituent elements [C] ([C ']) and [D] ([D']) in combination, the composite material is provided with high impact resistance while maintaining the handling property of the prepreg. It was surprisingly found that the interlaminar toughness G _IC and the plate edge peel strength (EDS) of the cross laminated plate can be improved, and the high interlaminar shear strength and heat resistance can be maintained. Moreover, the fact that these physical properties have little dependency on molding conditions is also a major feature.

Although the material of the constituent element [C] ([C ']) can be widely used, the thermoplastic resin fine particles are particularly suitable. The thermoplastic resin used as the fine particles, in the main chain, carbon-carbon bond, amide bond, imide bond, ester bond, ether bond, carbonate bond,
A typical example is a thermoplastic resin having a bond selected from a urethane bond, a urea bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond. Particularly, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyetherketone, polyetheretherketone, polyaramid, polyethernitrile, and polybenzimidazole are impact resistant. It is suitable as a material for the fine particles used in the present invention because of its excellent properties. Among these, polyamide, polyamideimide, and polyimide are suitable for the present invention because they have high toughness and good heat resistance. Polyamide is particularly excellent in toughness, and it is possible to have heat resistance by using one belonging to amorphous transparent nylon.

Resin fine particles which are semi-IPN-ized or semi-IPN-convertible by a combination of a thermoplastic resin and a thermosetting resin as the constituent element [C] ([C ']) are excellent in solvent resistance, and the composite material is a composite material. It is preferable because the overall solvent resistance is maintained. Here, IPN is an interpenetrating polymer network (Interpene).
Abbreviation for trading Polymer Network) and refers to an interpenetrating network structure between crosslinked polymers, while semi-IPN refers to an interpenetrating network structure between a crosslinked polymer and a linear polymer.

As a means for producing such a semi-IPN, a method of heating and melting a thermoplastic resin and a thermosetting resin to uniformly mix them, and then cooling to form a block,
A method in which a thermoplastic resin and a thermosetting resin are dissolved in a common solvent and uniformly mixed, and then the solvent is volatilized to be removed to form a block, and the thermoplastic resin and the thermosetting resin are dissolved in a common solvent and uniformly mixed. After that, it is sprayed and dried.
So-called spray-drying method, so-called spray reprecipitation method, thermoplastic resin, in which thermoplastic resin and thermosetting resin are dissolved in a common solvent and uniformly mixed The thermosetting resin and the thermosetting resin are dissolved in a common solvent, and while the solution is being stirred, a dispersion medium that is not compatible with the solution is gradually added to disperse the solution in the dispersion medium. There is a method to collect as.

Semi-IP with thermoplastic resin and thermosetting resin
When N-converted fine particles are used, by selecting the composition thereof, it is possible to obtain fine particles having good solvent resistance and good adhesion to the matrix resin while maintaining the toughness of the particles themselves.
However, it does not matter if this semi-IPN conversion is achieved during molding of the composite material. This is a component [C]
The composite material obtained by molding the prepreg with
It is preferable because it has excellent solvent resistance and fatigue resistance.

The ratio of the thermoplastic resin to the thermosetting resin in the semi-IPN resin fine particles makes the solvent resistance of the fine particles excellent, while the impact resistance of the composite material is poor due to insufficient toughness of the fine particles. From the viewpoint of prevention, the weight fraction of the thermoplastic resin is preferably 30 to 99%, more preferably 50 to 98%.

In the semi-IPN resin fine particles, even if the weight fraction of the thermosetting resin is unexpectedly small, about 2%, the effect of improving the solvent resistance is large, and the fatigue characteristics are also rapidly improved.

On the other hand, it is considered that the thermoplastic resin fine particles to be used have a reduced toughness due to the formation of semi-IPN with the thermosetting resin. Therefore, the impact resistance of the composite material is lower than that when the thermoplastic resin fine particles themselves are used. It is usually expected that the impact resistance tends to improve in a range where the weight fraction of the thermosetting resin is small. It is considered that this is because the adhesion between the fine particles and the matrix resin is improved by the semi-IPN formation.

Component [C] is a semi-IPN formed from polyamide and epoxy resin, or semi-IPN
In the case of fine particles capable of forming the above, a composite material which is the final end product has an optimum balance of various characteristics such as impact resistance, solvent resistance, fatigue property, and heat resistance.

As the constituent element [C] ([C ']), thermosetting resin fine particles may be used. In this case, the toughness of the fine particles themselves is lower than that of the thermoplastic resin. However, when the fine particles of the constituent element [D] having a sufficiently high toughness are used in combination, the toughness of the matrix resin of the constituent element [B ′] is further decreased. When combined with a sufficiently high resin, even if the toughness of the fine particles of the constituent element [C] ([C ′]) is not great, the presence of [C ′] stabilizes the highly tough resin layer in the laminated interlayer portion. Since it is formed as described above, the impact resistance, interlaminar toughness, and plate edge peel strength of the composite material are greatly improved. In addition, the heat resistance is generally higher than that of the thermoplastic resin particles, and there is an advantage that it contributes to maintaining the heat resistance of the composite material. As such thermosetting resin, phenol resin,
Epoxy resins, maleimide resins, unsaturated polyester resins and the like are preferably used.

As the material of the constituent element [D], an amorphous thermoplastic resin is preferable because it dissolves in the constituent element [B] during molding. Amide bond, imide bond, ether bond,
It is preferable to use a thermoplastic resin having at least one bond selected from an ester bond and a ketone bond as a raw material because the balance between toughness and heat resistance is excellent. Specifically, it is preferable to use a resin selected from the group consisting of polyarylate, polyetherimide, polysulfone, polyethersulfone, and polyetherketone as a raw material from the viewpoint of improving the toughness, and the toughness value G _IC is 1500 J / m ^2. When the above resins are used as the raw materials, the effect of addition is more remarkable.

Components [C] ([C ']) and [D]
The component [B] ([B ']) is the amount of ([D'])
The range of 1 wt% to 30 wt% is suitable with respect to the total resin of the constituent elements [C] ([C ′]) and [D] ([D ′]). If it is less than 1% by weight, the effect of fine particles hardly appears, and if it exceeds 30% by weight, it becomes difficult to mix it with the base resin, and the tackiness and drapeability of the prepreg are significantly deteriorated.

In particular, while the rigidity of the constituent element [B '] is utilized for developing the compressive strength of the composite material, the interlayer [C'] or [D '] having a large fracture elongation and a high toughness is used as an interlayer of the composite material. If the toughness of the
A lower range of 15% by weight is preferred.

A specific thermoplastic resin is blended with a thermosetting resin in a predetermined ratio, and a high toughness resin that forms a microphase-separated structure when cured is used in combination as a matrix resin of a constituent element [B ']. If so, a surprisingly small amount of components [C] ([C ']) and [D] such as 5%
By using ([D ']), high impact resistance, interlayer toughness, and plate edge peel strength can be obtained. Moreover, the component [C]
A smaller amount of ([C ']) and [D] ([D']) is more preferable for maintaining heat resistance and interlayer shear strength. The composite material in which [C ′] is localized in the laminated interlayer portion is
It contributes to stable formation of a high toughness interlayer thickness regardless of changes in curing conditions, and to impart excellent impact resistance, interlayer toughness, and plate edge peel strength. Moreover, the excellent impact resistance and interlaminar toughness are stably exhibited regardless of changes in molding conditions. The constituent element [C ′] has a thickness of 10 to 70 μm between the laminated layers.
This is because it plays a role of stably forming the resin layer.

The ratio of the constituent element [C] ([C ']) to the constituent element [D] ([D']) can be variously selected and designed according to the use and purpose of using the composite material. In a design that emphasizes compressive strength, especially compressive strength at high temperature and interlaminar shear strength, [C] ([C ′]): [D] ([D ′]) =
The range of 9: 1 to 3: 7 is preferable, and more preferably 9:
The range is from 1 to 4: 6. On the contrary, in a design that emphasizes interlayer toughness and plate edge peel strength, [C] ([C ']): [D]
The range of ([D ']) = 7: 3 to 1: 9 is preferable, and the range of 6: 4 to 2: 8 is more preferable.

In the composite material after molding, the constituent elements [C '] and [D'] are localized and exist between the laminated interlayer portions of the composite material, which are high in impact resistance, interlayer toughness, and further excellent. It is important to give the strip edge peel strength. Preferably, in a fiber-reinforced plastic in which a plurality of layers each composed of the constituent element [A] and the constituent element [B] are laminated, the constituent element [C ′] and the constituent element [C ′] in the “interlayer region” sandwiched between the layers. This is the case where 90% or more of the total amount of [D ′] is localized.

In the present invention, the “interlayer region” is a region formed in a portion where a layer composed of the constituent element [A] and the constituent element [B] is in contact with the upper and lower layers as shown in FIG. ., Where t is the average thickness of each layer, 0.15 t is vertically inserted in the thickness direction from the surface where the layers are in contact with each other by 0.15 t.
A region having a thickness of 3t. When 90% or more of the constituent elements [C '] and [D'] are localized in a region having a thickness of 0.2t, which is 0.1t vertically in the thickness direction from the surface where the layers contact each other. Can be said to be more preferable because the effect of the present invention appears more remarkably.

When the above conditions are not satisfied and a large amount of the constituent elements [C '] and [D'] are present deeply inside the layer beyond the "interlayer region", the impact resistance and the interlaminar toughness of the fiber reinforced plastic are obtained. , The effect of improving EDS is small, and the compression strength and heat resistance may be impaired.

The distribution state of the constituent elements [C '] and [D'] in the composite material is evaluated as follows. First, the composite material is cut perpendicularly to the laminated surface, and its cross section is cut into 70
Enlarge the image more than twice to create a photograph of 200 mm x 200 mm or more. The photographs are taken so that the plane direction of the layers is parallel to one side of the photographs.

Using this cross-sectional photograph, first, the average layer thickness is determined. The average thickness of a layer is obtained by measuring the thickness of a laminated portion of at least 5 layers or more at 5 places arbitrarily selected on the photograph and dividing the value by the number of laminated layers. Next, enlarge the cross section of the same composite material by 400 times or more to 200 mm × 20
A photograph of 0 mm or more is produced. Using this photograph, pay attention to one layer, and draw a line at the center of the layer.

Next, two lines are drawn symmetrically with respect to the center line at an interval of 15% of the average thickness of the layer previously obtained from this center line. 15% of the average thickness of the layer in the picture + 1
A portion surrounded by two lines having an interval of 5% = 30% is an “interlayer region”. Similarly, two lines above and below are drawn symmetrically with respect to the center line thereof at intervals of 50% of the average thickness of the layer.
The portion surrounded by two lines with a spacing of 50% + 50% = 100% of the average thickness is the thickness of one layer, that is, the average thickness itself.

Therefore, the areas of the constituent elements [C '] and [D'] in the "interlayer area" and the total area of the constituent elements [C '] and [D'] in the area showing the thickness of the above-mentioned one layer are calculated. The ratio of the constituent elements [C ′] and [D ′] existing in the “interlayer region” is calculated by quantifying and taking the ratio. Here, the area quantification of the constituent elements [C ′] and [D ′] is performed by cutting out all the constituent elements [C ′] and [D ′] existing in a predetermined area from the cross-sectional photograph and weighing them. To do.

When it is difficult to distinguish the constituent elements [C '] and [D'] from the constituent resin [B '] which is a matrix resin, one of them is selectively dyed and observed. In particular, the composition [D '] is such that the constituent element [D] once dissolves during molding.
It is a resin phase that loses its original form and is localized in the interlayer portion of the composite material and is distinguished from the constituent elements [B] or [C]. Observe after staining either phase with osmium tetroxide etc. It is preferable. The microscope can be observed with an optical microscope, but a scanning electron microscope is more suitable for observation depending on the staining method.

The localized presence of the constituent elements [C '] and [D'] in the laminated interlayer portion of the composite material means that the constituent elements [C] and [D] can be replaced by the form of the prepreg before molding. That is, most of them are localized near the prepreg surface. In particular components [C] and [D]
90% or more of the prepreg surface exists within the depth range of 30% of the thickness of the prepreg, the condition [C], [D] is deeper inside the prepreg than this condition. The impact resistance, interlaminar toughness, and plate edge peel strength of the composite material are remarkably excellent. When 90% or more of [C] and [D] are localized within the depth range of 20% of the thickness of the prepreg from the prepreg surface, a more remarkable effect is exhibited and the depth of 10% is increased. It is more preferable if it is localized within the range. As such a localization means, known means disclosed in Japanese Patent Laid-Open No. 1-266651, which will be described later, can be adopted.

The component [C] in the prepreg,
The distribution of [D] is optimal as long as it is similarly localized on both surfaces of the prepreg, because the prepreg can be freely laminated regardless of the front and back surfaces. However, even with prepregs in which fine particles have a similar distribution on only one side of the prepreg, the same effect can be obtained if the prepregs are laminated with care so that the fine particles are always between the prepregs. The distribution in which the fine particles [C] and [D] are biased only on one surface is also included in the present invention.

The distribution state of the constituent elements [C] and [D] in the prepreg is evaluated as follows. First,
The prepreg is sandwiched between the two smooth support plates, and the temperature is gradually raised to cure over a long period of time. At this time, the important thing is to gel at a temperature as low as possible. If the temperature is suddenly raised before gelation occurs, the resin in the prepreg will flow and the fine particles will move, so an accurate distribution state cannot be evaluated in the prepreg.

After gelation, the temperature of the prepreg is gradually increased over a period of time to cure the prepreg. The cross section of this cured prepreg is enlarged 200 times or more,
Take a picture of mm x 200 mm or more.

Using this photograph of the cross section, first, the average thickness of the prepreg is obtained. The average thickness of the prepreg is measured on at least 5 places on the photograph, and the average is taken. Next, a line is drawn parallel to the surface direction of the prepreg at a position of 30% of the thickness of the prepreg from the surface in contact with both the support plates. The area of fine particles existing between the surface in contact with the support plate and the parallel line of 30% was quantified on both surfaces of the prepreg, and the total area of fine particles existing over the entire width of the prepreg was quantified, and the ratio was calculated. As a result, the proportion of fine particles present within the depth of 30% from the surface of the prepreg is calculated. The area of the fine particles is quantified by cutting out all the fine particle portions existing in a predetermined region from the cross-sectional photograph and weighing the weight. In order to eliminate the influence of the variation in the partial distribution of fine particles, this evaluation is performed over the entire width of the obtained photograph, and the same evaluation is performed for five or more arbitrarily selected photographs, and the average is taken. There is a need.

When it is difficult to distinguish the fine particles from the matrix resin, one of them is selectively dyed for observation. The microscope can be observed with an optical microscope, but depending on the staining method, the scanning electron microscope may be more suitable for observation.

Component [C] ([C ']), [D]
The shape of ([D ']) is not limited to the spherical shape. Of course, it may have a spherical shape, but it may be in a variety of irregular shapes such as fine powder obtained by crushing a resin block or fine particles obtained by a spray dry method or a reprecipitation method.
In addition, even in the form of milled fiber obtained by cutting the fiber into short pieces,
It may be needle-shaped or whisker-shaped. In particular, in the fiber-reinforced composite material after molding, there may be a change in the form before molding and particles fused to each other to some extent.
In particular, [D '] loses its original form and becomes indeterminate. However, the viscosity of the resin composition containing [C] and [D] is lower when [C] and [D] are spherical than when it is non-spherical, which is preferable because prepregs can be easily produced.

The size of the fine particles is expressed by the particle size, and the particle size in this case means the volume average particle size determined by the centrifugal sedimentation velocity method or the like. Component [C] ([C ']),
The size of [D] ([D ']) is
It should not be so large as to significantly disturb the arrangement of the reinforcing fibers.
If the particle size exceeds 100 μm, the arrangement of the reinforcing fibers is disturbed, or the layers of the composite material obtained by laminating the layers are thickened more than necessary, which causes a drawback that the physical properties of the composite material are deteriorated. To form a more appropriate interlayer thickness, [C]
The particle size of ([C ']) or [D] ([D']) is 3 to 7
The range of 0 μm is preferable.

As a method for producing a prepreg in which the constituent elements [C] and [D] are localized on the surface, there are disclosed in JP-A-1-26651 and JP-A-63-170427.
As disclosed in JP-A-63-170428, a method of attaching the constituent elements [C] and [D] to the surface of a prepreg made of a reinforcing fiber and a matrix resin prepared in advance, and the constituent element [C] ], [D] are uniformly mixed in the matrix resin, and in the process of impregnating the reinforcing fibers, they are localized on the surface of the prepreg by the filtration phenomenon due to the fiber gap, and a part of the matrix resin is impregnated in the reinforcing fibers. It is also possible to adopt a method in which a primary prepreg is first produced, and then a film of the remaining matrix resin containing the constituent elements [C] and [D] in a high concentration is attached to the surface of the primary prepreg.

[0087]

The present invention will be described in more detail with reference to the following examples. Example 1 A unidirectional prepreg having the following constitution was manufactured. To manufacture prepreg, first of all,
A prepreg having a resin containing B and B at a weight fraction of 21% was prepared, and a resin film obtained by thinly applying a blended resin of C, D, and B onto release paper was attached to both surfaces of the prepreg. The parts by weight of C and D below are the amounts of fine particles contained in the prepreg resin finally obtained through the above two-step process. A reinforcing fiber-carbon fiber T800H (manufactured by Toray Industries, Inc.) B thermosetting resin composition-resin having the following composition 1 tetraglycidyl diaminodiphenylmethane (Sumitomo Chemical Co., Ltd. ELM434) ... 70 weight Part 2 Bisphenol A type epoxy resin (Yukaka Shell Epoxy Co., Ltd., Epicoat 828) ... 10 parts by weight 3 Bisphenol F type epoxy resin (Dainippon Ink and Chemicals Co., Epicron 830) ... 20 parts by weight 44,4′-diaminodiphenyl sulfone (Sumitomo Chemical Co., Ltd., Sumicure S) ... 45 parts by weight C nylon 12 fine particles (Toray Co., SP-500) ... Fine particles having an average particle size of 20 μm obtained by freeze-pulverizing 6 parts by weight of D polyether sulfone (4100G, manufactured by Mitsui Toatsu Co., Ltd.) ... 8 The amount part

The weight fraction of resin in the prepreg was 35%. Resin amount per unit area 103 g / ^{m 2,} carbon fiber weight per unit area was 191 g / ^{m 2.}
The prepreg was sandwiched between two smooth Teflon plates and gradually heated to 150 ° C. for 2 weeks to be cured, and the cross section was observed and a micrograph was taken. When the amount of fine particles present in the range from the prepreg surface to a depth of 30% of the prepreg thickness was evaluated, the value was 99%, and the fine particles were sufficiently localized near the prepreg surface.

Next, 24 sheets of this prepreg were laminated in a pseudo isotropic structure ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ s) and molded by a normal autoclave at 180 ° C. for 2 hours at 6 kgf. It was performed under a pressure of / cm ² .

The cross section of the molded product was polished, stained with osmium tetroxide, and the cross section was observed with a scanning electron microscope. Nylon 12 fine particles existed separately from the matrix resin in the interlayer region. The polyether sulfone fine particles were dissolved during molding and lost the particle shape, but they were localized in the interlayer portion.

The evaluation of the average thickness of the layer was performed by taking a photograph magnified 50 times and averaging five points to obtain 190 μm.
Met. Next, the ratio of the fine particles and the amorphous phase existing in the interlayer region was evaluated by using five cross-sectional photographs of an arbitrary portion magnified 400 times, and it was 100% (the width of the interlayer region was 33.5 μm). Was localized to.

This pseudo isotropic cured plate was 150 mm long and 1 mm wide.
Cut to 00 mm, centered at 1500 inch-pounds /
After applying a falling weight impact of inch, the damage area was 0.7 inch ² when measured with an ultrasonic flaw detection imaging device M400B manufactured by Canon / Holonics. Then ASTM
As a result of a compression test according to D-695, 50.2k
The residual compressive strength of si was shown. Table 1 shows the results of the same post-impact compression test conducted on the cured plates with different molding conditions. The physical properties were stable regardless of the molding conditions.

Twenty-four layers of prepreg were laminated in one direction to form a cured plate. A length (fiber direction) of 80 mm and a width (fiber orthogonal direction) of 12.7 mm were cut out, and two cuts were made in the thickness direction from the front to the center and the back to the center (FIG. 2). The distance between the two cuts is 6.3 mm, and the cut depth is t / 2 + 0.25 mm where t is the thickness of the test piece. The compression interlaminar shear strength (CILS) was determined to be 11.0 ksi.

Further, when the interlaminar toughness of the composite was measured for 20 layers of prepregs laminated in one direction, the peeling mode toughness G _IC was 640 J / m ² (double cantilever beam method).

(± 25 / ± 25/90) 10 in _S configuration
A tensile test was performed using a cured plate that was laminated in layers and molded, and the strength at which plate edge peeling occurred, that is, EDS, was determined to be 69.6 ksi.

Using a cured plate formed by laminating 6 layers of prepregs in one direction, the cured plate was used for 82 hours after being absorbed in warm water (72 ° C.) for 2 weeks.
The compression strength at ℃ was 187 ksi.

Example 2 A unidirectional prepreg having the following constitution was manufactured. The prepreg is manufactured by first preparing a prepreg of the resin consisting of A and B below with a weight fraction of 21%, and applying a resin film thinly coated with a blended resin of C, D and B on the release paper on both sides of the prepreg. It went by putting on. The parts by weight of C and D below are the amounts of fine particles contained in the prepreg resin finally obtained through the above two-step process. A reinforcing fiber-carbon fiber T800H (manufactured by Toray Industries, Inc.) B thermosetting resin composition-resin having the following composition 1 triglycidyl paraaminophenol (manufactured by Yuka Shell Epoxy Co., Ltd.) Epicoat YX-4 .. 40 parts by weight 2 bisphenol A type epoxy resin (Eikaka Shell Epoxy Co., Ltd., Epicoat 828) ... 20 parts by weight 3 bisphenol F type epoxy resin (Dainippon Ink and Chemicals Co., Ltd., Epicron 830)・ ・ ・ 40 parts by weight 4 4,4′-diaminodiphenyl sulfone (Sumitomo Chemical Co., Ltd., Sumicure S) ... 42 parts by weight 5 polyether sulfone (Mitsui Toatsu Co., Ltd., 5003P) .... 10 parts by weight C Polyamide imide (Amorco Torlon 4000T) fine particles having an average particle size of 27 μm obtained by freeze-grinding .. 6 parts by weight D polyetherimide (Ultem 1000 manufactured by GE Plastics Japan Co., Ltd.) fine particles having an average particle size of 18 .mu.m obtained by freeze-pulverization ... 8 parts by weight

The weight fraction of resin in the prepreg was 36%. Resin amount per unit area 109 g / ^{m 2,} carbon fiber weight per unit area was 192 g / ^{m 2.}
The prepreg was sandwiched between two smooth Teflon plates and gradually heated to 150 ° C. for 2 weeks to be cured, and the cross section was observed and a micrograph was taken. When the amount of fine particles present in the range from the prepreg surface to a depth of 30% of the prepreg thickness was evaluated, the value was 97%, and the fine particles were sufficiently localized near the prepreg surface.

Next, 24 sheets of this prepreg were laminated in a pseudo isotropic structure ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ s) and molded by a normal autoclave at 180 ° C. for 2 hours at 6 kgf. It was performed under a pressure of / cm ² .

The cross section of the molded product was polished and the cross section was observed with a microscope. The polyamide-imide fine particles existed separately from the matrix resin in the interlayer region. The polyetherimide fine particles dissolved during molding and lost the particle shape, but were localized in the interlayer portion.

The average thickness of the layer was evaluated by taking a photograph magnified 50 times and averaging five points to obtain 191 μm.
Met. Next, the ratio of the fine particles and the amorphous phase existing in the interlayer region was evaluated by using 5 cross-sectional photographs of an arbitrary portion magnified 400 times, and it was 96% (width of the interlayer region was 49.3 μm). Was localized to.

This pseudo isotropic hardened plate was 150 mm in length and 1 in width.
Cut to 00 mm, centered at 1500 inch-pounds /
After applying a falling weight impact of inch, the damage area was measured by an ultrasonic flaw detection imaging device M400B manufactured by Canon / Holonics Co., and found to be 1.0 inch ² . Then ASTM
As a result of a compression test according to D-695, 48 ksi
The residual compressive strength of

When the interlaminar toughness of the composite was measured for 20 layers of prepregs laminated in one direction, the peeling mode toughness G _IC was 540 J / m ² (double cantilever beam method).

(± 25 / ± 25/90) 10 in _S configuration
A tensile test was conducted using a cured plate laminated in layers and molded, and the strength at which plate edge peeling occurred, that is, EDS was first determined to be 63.7 ksi.

Using a cured plate obtained by laminating 24 layers of prepregs in one direction and molding, the compression interlaminar shear strength (CILS) was 11.2 ksi. Using a cured plate formed by laminating 6 layers of prepreg in one direction, hot water (7
The compressive strength at 82 ° C. after absorbing water in 2 ° C. was 190 ksi.

Example 3 Part A: Synthesis of Reactive Polyimide Oligomer 218 g (0.75 mol) under nitrogen substitution in a 3000 ml separable flask equipped with a nitrogen inlet, thermometer, stirrer and dehydration trap. ) 1,3-bis (3-aminophenoxy) benzene (APB), 33 g
(0.094 mol) 9,9'-bis (4-aminophenyl) fluorene (FDA), 122 g (0.094 mol)
mol) NH ₂ equivalent of 650 amino-terminated dimethyl siloxane (commercially available BY-16-853, Toray Silicone Co., Ltd.)
2000 ml of N-methyl-2-pyrrolidone (NM
It was dissolved in P) with stirring. 250 g (0.85 mol) of solid biphenyltetracarboxylic dianhydride was added thereto little by little, and the mixture was stirred at room temperature for 3 hours, then heated to 120 ° C. and stirred for 2 hours. After returning the flask to room temperature and adding 50 ml of triethylamine and 50 ml of toluene, the temperature was raised again and azeotropic dehydration was performed at 160 ° C. to obtain about 30 ml of water. After cooling the reaction mixture, it was diluted with twice the volume of NMP and slowly poured into 201 acetone to precipitate the amine-terminated siloxane polyimide oligomer as a solid product.

Then, the precipitate was vacuum dried at 200 ° C. When the number average molecular weight (Mn) of this oligomer was measured by gel permeation chromatography (GPC) using a dimethylformamide (DMF) solvent, it was 4,900 in terms of polyethylene glycol (PEG). The glass transition point was 189 ° C. according to a differential thermal analyzer (DSC). In addition, the introduction of the siloxane skeleton and the fact that it is an amine terminal indicate that the NMR spectrum and IR
It was confirmed from the spectrum.

Part B: Preparation of Resin for Component B and Measurement of Resin Physical Properties In a beaker, 24 parts of the above-mentioned siloxane polyimide oligomer of Part A and a phenol novolac type epoxy resin (Epicote 154, manufactured by Yuka Shell Epoxy Co., Ltd.) 40
Parts, 30 parts of bisphenol A type epoxy resin (Epoxycoat 825, manufactured by Yuka Shell Epoxy Co., Ltd.), and 30 parts of bisphenol F type epoxy resin (Epiclon 830, manufactured by Dainippon Ink and Chemicals, Inc.) were weighed. 120 it
The oligomer was dissolved in the epoxy resin by heating at 0 ° C for 2 hours. Next, 34,4'-diaminodiphenylsulfone (Sumiture S, manufactured by Sumitomo Chemical Co., Ltd.) was used.
Parts were added and mixed at 140 ° C. for 10 minutes to dissolve.

A vacuum pump was connected to the container for vacuum degassing, and then the mold was subjected to a mold release treatment in which the contents were preheated to 120 ° C. (the size of the void was 120 × 120).
X 3 mm). Curing reaction was performed in an oven at 130 ° C. for 2 hours + 180 ° C. for 2 hours to prepare a resin cured plate having a thickness of 3 mm.

The Tg of the obtained cured resin was 201 ° C. When the sample was cut out from this and the fracture strain energy release rate G _IC was measured, it was 430 J / m ² , and the flexural modulus was 350 kg / mm ² .

When the polished surface of the cured resin is dyed with osmic acid and the backscattered electron image is observed with a scanning electron microscope, basically two phases together form a continuous phase, and the dispersed phase of the other phase is inside each of them. A complex microphase-separated structure with the existence of was found. Further, elemental analysis of the same field of view by an X-ray microanalyzer revealed that the silicon element is densely distributed in the high contrast phase which appears black in the photograph.

Part C: Preparation of prepreg and composite material and measurement of physical properties A unidirectional prepreg having the following constitution was produced. The prepreg is manufactured by first preparing a prepreg of the resin consisting of A and B below with a weight fraction of 21%, and applying a resin film thinly coated with a blended resin of C, D and B on the release paper on both sides of the prepreg. It went by putting on. The parts by weight of C and D below are the amounts of fine particles contained in the prepreg resin finally obtained through the above two-step process. A reinforcing fiber-carbon fiber T800H (manufactured by Toray Industries, Inc.) B thermosetting resin composition-resin consisting of the following composition 1 phenol novolac type epoxy resin (Epicote 154, manufactured by Yuka Shell Epoxy Co., Ltd.) ...・ 40 parts by weight 2 Bisphenol A type epoxy resin (Eikaka Shell Epoxy Co., Ltd., Epicoat 825) ... 30 parts by weight 3 Bisphenol F type epoxy resin (Dainippon Ink and Chemicals Co., Ltd., Epicron 830) ・・ ・ ・ 30 parts by weight 4,4'-diaminodiphenyl sulfone (Sumiture S, manufactured by Sumitomo Chemical Co., Ltd.) ・ ・ ・ ・ 34 parts by weight 5 Siloxane polyimide oligomer described in A part ・ ・ ・ ・ 24 parts by weight C Fine particles with an average particle size of 23 μm obtained by freeze-pulverizing amorphous transparent nylon (Trogamide-T manufactured by Diminat Novel Co., Ltd.) Parts D polysulfone (Amoco Japan Ltd., Udel P-1700) Mean particle size 20μm of fine particles obtained by freeze-grinding a. ． ． ． 5 parts by weight

The weight fraction of resin in the prepreg was 36.6.
%Met. Resin amount per unit area is 109 g /
m ² and the amount of carbon fiber per unit area were 191 g / m ² . The prepreg was sandwiched between two smooth Teflon plates and gradually heated to 150 ° C. for 2 weeks to be cured, and the cross section was observed and a micrograph was taken. When the amount of fine particles present in the range from the prepreg surface to a depth of 30% of the prepreg thickness was evaluated, the value was 100.
%, And the fine particles were well localized on the prepreg surface.

Next, 24 sheets of this prepreg were laminated in a pseudo isotropic structure ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ s) and molded by a normal autoclave at 180 ° C. for 2 hours at 6 kgf. It was performed under a pressure of / cm ² .

The cross section of the molded product was polished and the cross section was observed with a microscope. The amorphous transparent nylon fine particles existed separately from the matrix resin in the interlayer region. The polysulfone fine particles were dissolved during molding and lost the particle shape, but they were localized in the interlayer portion.

The evaluation of the average thickness of the layer was performed by taking a photograph magnified 50 times, and the average of 5 points was 190 μm.
Met. Next, the ratio of the fine particles and the amorphous phase existing in the interlayer region was evaluated using 5 cross-sectional photographs of an arbitrary portion magnified 400 times, and it was 100% (width of the interlayer region was 29.2 μm). Was localized to.

This pseudo isotropic cured plate was 150 mm long and 1 mm wide.
Cut to 00 mm, centered at 1500 inch-pounds /
After applying an impact of inch drop weight, the damage area was measured with an ultrasonic flaw detection imaging device M400B manufactured by Canon / Holonics Co., and found to be 0.6 inch ² . Then ASTM
As a result of a compression test according to D-695, 55.5 k
The residual compressive strength of si was shown.

Further, when the interlaminar toughness of the composite was measured for 20 layers of prepregs laminated in one direction, the peeling mode toughness G _IC was 640 J / m ² (double cantilever beam method).

(± 25 / ± 25/90) 10 in _S configuration
A tensile test was performed using a cured plate that was laminated in layers and molded, and the strength at which plate edge peeling occurred, that is, EDS, was determined to be 73.5 ksi.

Using a cured plate obtained by laminating 24 layers of prepreg in one direction and molding, the compressive interlaminar shear strength (CILS) was found to be 11.4 ksi. Using a cured plate formed by laminating 6 layers of prepreg in one direction, hot water (7
The compressive strength at 82 ° C. after absorbing water in 2 ° C. was 178 ksi.

[Comparative Example 1] The same procedure as in Example 1 was repeated except that the addition amount of the constituent element C was increased to 14 parts by weight instead of removing the constituent element D. When the amount of fine particles present in the range from the prepreg surface to a depth of 30% of the prepreg thickness was evaluated, the value was 99%, and the fine particles were sufficiently localized on the prepreg surface.

Next, the cross section of the molded product obtained by laminating 24 sheets of this prepreg in a pseudo isotropic structure ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ s) was polished and observed with a microscope. As a result, the fine particles existed separately from the matrix resin in the interlayer region. The average thickness of the layers is 19
It was 0 μm. The ratio of fine particles existing in the interlayer region was 99%, which was localized between the layers.

After applying a falling weight impact of 1500 inch-pounds / inch to the center of this pseudo isotropic cured plate, the damaged area was measured and found to be 0.6 inch ² . Then, as a result of a compression test, a high residual compression strength of 52 ksi was shown.

However, when CILS was determined using a cured plate obtained by laminating 24 layers of prepreg in one direction and molding,
The value was 7.2 ksi, which was significantly inferior to the examples. Also, using a cured plate formed by laminating 6 layers of prepregs in one direction, 82 ° C after absorbing water in warm water (72 ° C) for 2 weeks.
The compressive strength in Example was 141 ksi, which was significantly inferior to the examples.

[Comparative Example 2] The same procedure as in Example 1 was repeated except that the addition amount of the constituent element D was increased to 14 parts by weight instead of removing the constituent element C. When the amount of fine particles present in the range from the prepreg surface to a depth of 30% of the prepreg thickness was evaluated, the value was 97%, and the fine particles were localized on the prepreg surface.

Next, a cross section of a molded product obtained by laminating 24 sheets of this prepreg in a pseudo isotropic structure ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ s) was polished and observed with a microscope. As a result, the fine particles dissolved during molding and no particle shape was found. The average thickness of the layer is 190 μm
Met. The interlayer region was somewhat resin rich and had a thickness of about 10 μm.

After a falling weight impact of 1500 inch-pounds / inch was applied to the center of this pseudo-isotropic cured plate, the damaged area was measured and found to be 1.3 inch ² . Then, as a result of a compression test, the residual compressive strength of 36.1 ksi was considerably lower than that of the example. Table 1 shows the results of the same post-impact compression test conducted on the cured plates with different molding conditions. There was a large change in physical properties due to changes in molding conditions.

[0128] The compression interlaminar shear strength (CILS) of the cured plate obtained by laminating 24 layers in one direction and molding was 11.4.
It was ksi and was equivalent to the example. However, the peeling mode toughness G _IC of 20 layers of prepreg laminated in one direction was 280 J / m ² (double cantilever beam method), which was significantly inferior to the examples. Also, when the EDS of a cured plate formed by laminating 10 layers with a configuration of (± 25 / ± 25/90) _S was 31.5 k.
si, which was significantly inferior to the examples.

[0129]

EFFECTS OF THE INVENTION The prepreg according to the present invention, while ensuring the tackiness and drapeability as a prepreg, maintains high interlaminar shear strength when heat-molded into a composite material, and has excellent high impact resistance and interlaminar toughness. Have. Further, the occurrence of peeling at the plate edge when the laminated plate is pulled is significantly suppressed, and the fatigue resistance is excellent. Moreover, it provides an excellent fiber-reinforced composite material whose high physical properties are stably expressed despite changes in molding conditions such as temperature rising rate, curing temperature and pressure.

[0130]

[Table 1]

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an interlayer region of a prepreg and a fiber reinforced resin of the present invention.

FIG. 2 is a view showing a test piece for measuring compression interlaminar shear strength.

Claims (18)

[Claims] 1. A prepreg comprising the following constituents [A], [B], [C] and [D], wherein the constituents [C] and [D] are localized on the surface. . [A]: Reinforcing fiber consisting of long fibers [B]: Thermosetting resin composition [C]: Fine particles insoluble in component [B] [D]: Resin soluble in component [B] Fine particles 2. 90% or more of the constituent elements [C] and [D] are localized within a depth range of 30% of the thickness of the prepreg from the surface of the prepreg. The listed prepreg. 3. The constituent [C] is polyamide, polycarbonate, polyacetal, polyphenylene oxide,
Selected from the group consisting of polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyetherketone, polyetheretherketone, polyaramid, polyethernitrile, polybenzimidazole, epoxy resin, phenol resin and maleimide resin. The prepreg according to claim 1 or 2, which is made of a resin. 4. The component [C] is a thermosetting resin and a semi-I.
The prepreg according to claim 1 or 2, which is made of a PN thermoplastic resin. 5. The component [D] is made of a resin selected from the group consisting of polyarylate, polyetherimide, polysulfone, polyethersulfone, and polyetherketone, as a raw material. The listed prepreg. 6. The thermosetting resin in the constituent element [B] comprises at least one thermosetting resin selected from the group consisting of epoxy resins, cyanate resins and bismaleimide resins. The prepreg according to any one of 1. 7. The component [B] is a thermosetting resin composition in which a thermoplastic resin selected from polyether sulfone, polysulfone, polyimide, polyether imide and polyimide having a phenyltrimethylindane structure is mixed or dissolved. Claims 1 to 1 characterized in that
6. The prepreg according to any one of 6 above. 8. The prepreg according to any one of claims 1 to 6, wherein the constituent element [B] is a thermosetting resin composition in which a polyimide containing a siloxane skeleton is mixed or dissolved. 9. The prepreg according to claim 1, wherein the constituent element [B] is a thermosetting resin composition in which a polyimide having an amino group is mixed or dissolved. 10. The following components [A], [B '],
It consists of [C '] and [D'], and the component [C '],
A fiber-reinforced composite material, wherein [D '] is localized in a laminated interlayer portion. [A]: Reinforcing fiber consisting of long fiber [B ']: Thermosetting resin cured product [C']: Resin fine particle [D ']: Amorphous type distinguishable from constituent elements [B'] and [C '] Resin phase 11. Component 9 of [C '] and [D']
The fiber-reinforced composite material according to claim 10, wherein 0% or more is localized in the laminated interlayer portion. 12. The component [C ′] is polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polysulfone, poly The fiber-reinforced composite material according to claim 10 or 11, which is made of a resin selected from the group consisting of ether sulfone, polyether ketone, polyether ether ketone, polyaramid, polyether nitrile and polybenzimidazole. 13. The component [D ′] is polyamide, polyphenylene oxide, polyarylate, polyester,
Polyamide imide, polyimide, polyether imide,
A polyimide having a phenyltrimethylindane structure,
The fiber-reinforced composite material according to any one of claims 10 to 12, which is made of a resin selected from the group consisting of polysulfone, polyether sulfone, and polyether ketone. 14. The fiber-reinforced composite material according to claim 10, wherein the constituent [C ′] thermosetting resin and a semi-IPN-ized thermoplastic resin are used as raw materials. 15. The component [C ′] is made of at least one thermosetting resin selected from the group consisting of unsaturated polyester resins, phenol resins, epoxy resins and maleimide resins as a material. 11. The fiber-reinforced composite material according to item 11. 16. The thermosetting resin of the constituent element [B ′] comprises at least one thermosetting resin selected from an epoxy resin, a cyanate resin and a bismaleimide resin. The fiber-reinforced composite material according to any one of 1. 17. The component [B ′] is a thermosetting resin cured product containing a thermoplastic resin selected from polyether sulfone, polysulfone, polyimide, polyether imide, and polyimide having a phenyltrimethylindane structure. The fiber-reinforced composite material according to any one of claims 10 to 16, which is characterized by the above-mentioned. 18. The fiber-reinforced composite material according to claim 10, wherein the constituent element [B ′] is a thermosetting resin cured product containing a polyimide having a silicon element.