JP3312441B2 - Prepreg and fiber reinforced plastic - Google Patents

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 structural body which is required to have high strength, elastic modulus, specific strength and specific elastic modulus obtained by dividing these by specific gravity as an advanced composite material. It relates to a fiber-reinforced plastic which is a molded product.

[0002]

2. Description of the Related Art An advanced composite material is a non-uniform material having a reinforcing fiber and a matrix resin as essential components. Therefore, there is a great difference between physical properties in a fiber axis direction and physical properties in other directions. . For example, it is known that the resistance to falling weight impact does not lead to a drastic improvement even if the strength of the reinforcing fiber is improved. In particular, a composite material using a thermosetting resin as a matrix resin has insufficient impact resistance due to the low toughness of the matrix resin. In addition, when a tensile load is applied to the crossed laminated plate, delamination often occurs from the end of the plate, and therefore, the degree of freedom of 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 a 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 an epoxy resin is described. 61-2
No. 28016. It is stated that the impact resistance of the composite material is also improved by increasing the resin toughness.

JP-A-60-63229 discloses that impact resistance is improved by disposing an epoxy resin film modified with an elastomer between layers of a fiber-reinforced prepreg.

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

The present inventors have disclosed in 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 referred to as tackiness and drapeability) of the prepreg is provided. That was shown.

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 consisting of 5 micron elastomeric particles provides a composite material having improved impact resistance. Here, it is stated that a phase separation structure is formed in the cured resin portion other than the elastomer particles.

[0008] EP-A-0 377 194 A
In the specification 2, the impact resistance of the composite material can be improved by using an epoxy resin mixed with epoxy-soluble polyimide particles (particle diameter: 2 to 35 μm) having a partially non-aromatic skeleton such as aminophenyltrimethylindane as a matrix resin. It is disclosed that the performance is improved. According to the publication, the soluble polyimide particles dissolve during molding between the interlayers of the composite material.

Japanese Patent Application Laid-Open No. Hei 3-26750 states that a composite material comprising a matrix resin containing resin fine particles comprising an epoxy resin, a reactive polysulfone oligomer, and a reactive elastomer and an epoxy resin has excellent impact resistance.

[0010]

However, these methods still have insufficient impact resistance improving effects,
Each has drawbacks, such as sacrificing interlaminar shear strength, handling, and other properties to improve impact resistance.

When a thermoplastic resin such as polysulfone having a high molecular weight is mixed to improve the resin toughness as disclosed in Japanese Patent Application Laid-Open No. 60-243113, the viscosity of the resin composition becomes too high to impregnate the reinforcing fibers. And prepreg tack and drape properties are impaired. JP-A-61-228
Even when an oligomer having a reduced molecular weight is added as in JP-A-016, it is necessary to increase the amount of the thermoplastic resin sufficiently to obtain sufficient resin toughness, and the viscosity of the resin composition increases accordingly. This makes it difficult to impregnate the reinforcing fibers. Further, as the amount of the thermoplastic resin increases, the solvent resistance of the cured product decreases. In addition, even if the toughness of the resin itself is improved, the tendency to reach a plateau is gradually recognized for improving the impact resistance of the composite material.

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

When a thermoplastic resin film is used as disclosed 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 can be achieved to some extent, but tackiness (adhesiveness) and drapability, which are advantages of the thermosetting resin, are lost. In addition, the general disadvantage of thermoplastic resins that solvent resistance is poor is reflected in composite materials.

When the particles existing between the layers are elastomers as disclosed in US Pat. No. 4,863,787, the thickness of the layers tends to change due to changes in molding conditions such as pressure and heating rate. Impact resistance is easily affected by molding conditions. It is also believed that the presence of the elastomer reduces the interlaminar shear strength of the composite.

[0015] European Patent Publication 0377194 A2
Also in the case where a soluble polyimide is disposed between layers as in the specification, the interlayer thickness is liable to change due to a change in molding conditions, and the impact resistance is easily affected by the molding conditions.

Japanese Patent Application Laid-Open No. 3-26750 has no description of the compressive strength after impact (CAI) in the examples, so that the degree of impact resistance cannot be evaluated. However, particles containing an elastomer reduce the interlaminar shear strength. It is thought to be.

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

The present invention has an impact resistance and an interlayer toughness that are higher than those of the preceding examples while maintaining high interlayer shear strength and heat resistance, and furthermore, an edge peel strength (EDS) when a cross-laminated plate is pulled. It is an object of the present invention to provide a prepreg for providing a composite material having a significantly higher thermal resistance and a fiber-reinforced plastic obtained therefrom.

[0019]

The prepreg of the present invention has the following structure to achieve the above object. That is, the prepreg is composed of the following components [A], [B], [C] and [D], wherein the components [C] and [D] are localized on the surface. [A]: Reinforcing fiber composed of long fibers [B]: Thermosetting resin composition [C]: Fine particles made of resin [D]: Fine particles made of resin having a higher elastic modulus than [C] The fiber reinforced plastic of the present invention has the following configuration to achieve the above object. That is, it consists of the following components [A], [B '], [C'] and [D '],
The fiber reinforced plastic is characterized in that the constituent elements [C ′] and [D ′] are localized in the interlayer portion. [A]: Reinforcing fiber consisting of long fiber [B ']: Cured thermosetting resin [C']: Fine particles made of resin [D ']: Made of resin having higher elastic modulus than [C'] Fine particles

(Description of Constituent Element [A]) The element used as the constituent element [A] in the present invention is a reinforcing fiber composed of long fibers. The reinforcing fiber used in the present invention is a fiber having good heat resistance and tensile strength generally used as an advanced composite material. 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 them, carbon fibers and graphite fibers, which have a good specific strength and specific elastic modulus and greatly contribute to weight reduction, are most preferable in the present invention. Any type of carbon fiber or graphite fiber can be used as the carbon fiber or graphite fiber depending on the application, but high-strength carbon fiber having a tensile elongation of 1.5% or more is suitable for developing the strength of the composite material. I have. High-strength 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 a tensile elongation of 1.9.
% Or more of high strength and high elongation carbon fiber is most suitable. In the present invention, a long fiber-shaped reinforcing fiber is used, and its length is preferably 5 cm or more. If the length is shorter than that, it is difficult to sufficiently develop the strength of the reinforcing fiber as a composite material. Further, the carbon fiber and the graphite fiber may be used by being mixed with another reinforcing fiber. The shape and arrangement of the reinforcing fibers are not particularly limited. For example, the reinforcing fibers may be used in a single direction, a random direction, a sheet shape, a mat shape, a woven shape, or a braided shape. In particular, for applications requiring high specific strength and high inelastic modulus, an array in which reinforcing fibers are aligned in a single direction is most suitable, but a cross (woven) array which is easy to handle. Are also suitable for the present invention.

(Description of Components [B] and [B '])
The element used as the component [B] in the present invention is a thermosetting resin composition, and [B '] is a cured thermosetting resin obtained by curing [B]. When a thermosetting resin is used as a matrix resin, the fiber-reinforced composite material is advantageous over a thermoplastic resin itself as a matrix resin in that low-pressure molding by an autoclave is possible.

The thermosetting resin, which is a component of the component [B] and the component [B '], is cured by heat or external energy such as light or an electron beam, and is at least partially three-dimensionally cured. Is preferably used.

Specific examples of the thermosetting resin suitable for the present invention include an epoxy resin, and are generally used in combination with a curing agent or a curing catalyst. In particular, an epoxy resin using an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor is preferable. Specifically, epoxy resins using amines as precursors include tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol,
Various isomers of triglycidylaminocresol and epoxy resins using phenols as precursors include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, and cresol novolac epoxy resin. Examples of the epoxy resin using a compound having a carbon-carbon double bond as a precursor include, but are not limited to, alicyclic epoxy resins and the like. Further, brominated epoxy resins obtained by brominating these epoxy resins are also used. An epoxy resin having an aromatic amine represented by tetraglycidyldiaminodiphenylmethane as a precursor has a good heat resistance and a good adhesion to a reinforcing fiber, and is most suitable for the present invention.

An 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 has an active group capable of reacting with an epoxy group. A known epoxy curing agent can be appropriately used, and a compound having an amino group, an acid anhydride group, or an azide group is particularly suitable. Specifically, dicyandiamide, various isomers of diaminodiphenylsulfone, and aminobenzoic acid esters are suitable. More specifically, dicyandiamide is preferably used because of its excellent preservability. Further, various isomers of diaminodiphenyl sulfone are most suitable for the present invention because they give cured products having good heat resistance. As the aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used. Although the heat resistance is lower than that of diaminodiphenyl sulfone, the tensile elongation is low. It is selected according to the application because it is excellent.

It is also possible to mix a small amount of inorganic fine particles such as finely divided silica or an elastomer in the epoxy resin. Particularly, a small amount of elastomer is preferable in that the toughness of the resin is improved.

As the thermosetting resin in the component [B] and the component [B '], in addition to the epoxy resin, a maleimide resin, a resin having an acetylene terminal, a resin having a nadic acid terminal, and a cyanate ester terminal Resins, vinyl-terminated resins, and allyl-terminated resins are also preferably used. These may be used as appropriate by being mixed with an epoxy resin or another resin. 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 reduced.

The maleimide resin is a compound containing at least two maleimide groups per molecule on average. Bismaleimide using diaminodiphenylmethane as a raw material is particularly preferably used. Examples of this kind of maleimide compound include N, N'-phenylenebismaleimide, N, N'-hexamethylenebismaleimide, N, N'-methylene-di-p-phenylenebismaleimide, N, N'-oxy-di- p-phenylenebismaleimide, N, N'-4,4 '
-Benzophenone bismaleimide, N, N'-diphenylsulfonebismaleimide, N, N '-(3,3'-dimethyl) -methylene-di-p-phenylenebismaleimide, N, N'-4,4'-dicyclohexyl Methanebismaleimide, N, N'-m (or p) -xylylene-bismaleimide, N, N '-(3,3'-diethyl) -methylene-di-p-phenylenebismaleimide, N, N'
Examples include, but are not limited to, reaction products of a mixed polyamine, which is a reaction product of aniline and formalin, with maleic anhydride, such as bismaleimide of bis (aminophenoxy) benzene and metathylene-di-maleimide. Further, these maleimide compounds may be used in a mixture of two or more kinds, and N-allyl maleimide,
N-propylmaleimide, N-hexylmaleimide, N
-A monomaleimide compound such as phenylmaleimide may be contained.

The 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 the compound has an active group capable of reacting with a maleimide group. Known curing agents can be used as appropriate, and particularly, 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, and an epoxy group are suitable. I have. For example,
As a curing agent having an amino group, diaminodiphenylmethane is typical, and as a curing agent having an alkenyl group, there are 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 polyhydric phenol cyanate compound represented by bisphenol A is preferable. A resin combined with a cyanate ester resin and a bismaleimide resin is available from Mitsubishi Gas Chemical Company, Ltd. as BT.
It is commercially available as a resin and is suitable for the present invention. These are generally better in heat resistance and water resistance than epoxy resins, but are inferior in toughness and impact resistance, and are therefore preferably selected and used according to the application. Bismaleimide and cyanate ester are used usually in a weight ratio of 0/100 to 70/30. In the case of 0/100, the resin is a cyanate ester (triazine) resin, but is characterized by low water absorption, and 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, a nadiimide group, an acetylene group, a benzocyclobutene group and the like are preferable.

The thermosetting resin in component [B] and component [B '] is widely recognized in the industrial fields such as phenol resin, resorcinol resin, unsaturated polyester resin, diallyl phthalate resin, urea resin and melamine resin. Alternatively, a thermosetting resin may be used.

The fact that the constituent [B] and the constituent [B '] are thermosetting resins containing a thermoplastic resin component as a modifier improves the resin toughness as compared with the case where the thermosetting resin is used alone. preferable. Here, the thermoplastic resin component refers to a thermoplastic resin that is widely recognized in the industry, but it does not impair the inherent high heat resistance and high elastic modulus of the thermosetting resin. Those belonging to are preferred 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, and aromatic polycarbonate skeleton. Resins are typical, and specific examples include polyethersulfone, polysulfone, polyimide, polyetherimide, and polyimide having a phenyltrimethylindane structure.

As the thermosetting resin-soluble thermoplastic resin having high heat resistance, those having an aromatic polyimide skeleton are particularly preferable because they are excellent in all of heat resistance, solvent resistance and toughness. As these thermoplastic resins, commercially available polymers may be used, or those synthesized according to the purpose may be used. It is preferable to use a so-called oligomer having a lower molecular weight than a commercially available polymer because the toughness of the composite material can be increased 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 greatly contribute to improvement in toughness while maintaining the inherent solvent resistance of the thermosetting resin. Representative reactive termini include amino groups.

As a method for synthesizing an aromatic polyimide, which is particularly preferable as a thermoplastic resin to be 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 include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid Dianhydride, 3,3 ′, 4,4′-diphenylethertetracarboxylic dianhydride, 3,3 ′,
Aromatic tetracarboxylic dianhydrides such as 4,4'-diphenylsulfonetetracarboxylic dianhydride, more preferably 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3' And aromatic tetracarboxylic dianhydrides such as 4,4'-diphenyl ether tetracarboxylic dianhydride.

Preferred examples of the diamino compound include diaminodiphenylmethane, metaphenylenediamine, paraphenylenediamine, diaminodiphenylether, diaminodiphenylsulfone, diaminodiphenylsulfide, diaminodiphenylethane, diaminodiphenylpropane, diaminodiphenylketone, diaminodiphenylhexafluoropropane, Diaminodiphenylfluorene, bis (aminophenoxy) benzene, bis (aminophenoxy) diphenylsulfone, bis (aminophenoxy) diphenylpropane, bis (aminophenoxy) diphenylhexafluoropropane, fluorinated amine, dimethyl-substituted 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) diphenylsulfone, bis (aminophenoxy) diphenylpropane,
Bis (aminophenoxy) diphenylhexafluoropropane, diaminodiphenylfluorene, fluorenediamine, dimethyl-substituted diaminodiphenylmethane,
Aromatic diamino compounds such as tetramethyl-substituted diaminodiphenylmethane, diethyl-substituted diaminodiphenylmethane, tetraethyl-substituted diaminodiphenylmethane, and dimethyldiethyl-substituted diaminodiphenylmethane can be given.

As the thermoplastic resin contained in the component [B] and the component [B '], a block copolymer or a graft copolymer comprising a chain compatible with the thermosetting resin and a chain incompatible with the thermosetting resin. Is particularly preferred from the viewpoint of compatibility control.

One of the preferred embodiments is that the component [B]
The thermosetting resin is a block copolymer or a graft copolymer having a chain composed of a siloxane skeleton which is originally incompatible. A typical siloxane chain is a dimethylsiloxane skeleton, but 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 molecules of the thermoplastic resin contained in the component [B] have, as a block chain, a chain which is originally incompatible with the thermosetting resin component in the component [B], a completely compatible molecule having the same molecular weight is used. Compared with the case of a thermoplastic resin consisting only of a chain, the increase in resin viscosity due to the addition thereof is small. Therefore, there is little decrease in workability, and a prepreg using this resin as a matrix resin has an effect that tackiness and drapeability are excellent. From another viewpoint, the amount of thermoplastic resin added in the component [B] is less restricted, 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 component [B] means that the resin heat resistance is improved. preferable.

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

Here, the thermoplastic resin component in the component [B] may be previously dissolved in the uncured thermosetting resin component, or may be merely dispersed and mixed. Also,
It may be partially dissolved and partially dispersed. By changing the ratio of the dissolution and the dispersion, the viscosity of the resin can be adjusted, and the tackiness and drapeability of the prepreg can be adjusted to a desired degree. Most of the dispersed thermoplastic resin is also dissolved in the thermosetting resin component during the molding process. It is preferable to improve the toughness that the phase is separated again by the end of the curing to form the appropriate micro phase separated structure.

The molecular weight of the thermoplastic resin in the component [B] may be about 2 as a number average molecular weight when the thermoplastic resin component is previously dissolved in the uncured thermosetting resin component.
The range of 2,000 to 20,000 is preferred. When the molecular weight is smaller than this, the effect of improving the toughness is small, and when the molecular weight is larger than this, the viscosity of the resin increases significantly and the workability decreases significantly. More preferably about 2500-1000
It is in the range of 0. On the other hand, when the thermoplastic resin component in the component [B] is dispersed without being dissolved in the thermosetting resin component in an uncured state, the molecular weight of the thermoplastic resin is further preferably up to about 100000 which is a high molecular weight region. .

A thermoplastic resin soluble in a thermosetting resin is mixed or dissolved in the constituent element [B]. During the curing of the resin, a phase mainly composed of the thermosetting resin and a thermoplastic resin composed mainly of the thermoplastic resin are used. It is preferable that the cured resin [B ′] be microphase-separated into a cured phase from the viewpoint of improving the toughness of the composite material. In particular, the phase-separated structure after curing is a phase mainly composed of a thermoplastic resin and a phase separated from a phase mainly composed of a thermosetting resin, and at least a phase mainly composed of a thermoplastic resin, preferably It is preferable that both phases become a cured resin having a microphase-separated structure in which both phases are continuous three-dimensionally, because high toughness is obtained. It is more preferred to have a more complicated phase separation morphology containing a dispersed phase of another phase in the continuous phase.

By having a microphase-separated structure in which a phase mainly composed of a thermoplastic resin forms a continuous phase at least partially, a cured product having high elastic modulus and high toughness can be obtained. 250 kg / m as the component [B ′]
m ² or more, even more while maintaining the 300 kg / mm ² or more flexural modulus of at least 200 J / ^{m 2} or more, further 250 J / ^{m 2} or more fracture strain energy release rate G
It is preferably a cured product of a high toughness resin having an _IC .

The fracture 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 details on the DT method, see Journal of Materials Science (J
ourna1 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. Here ^{_{G IC = P 2 (ΔC /}} Δa f) / 2t, the compliance C is defined by C = [delta] P by the cross-head displacement δ and cracking load P during cracking.

(Description of Constituent Elements [C] ([C ']) and [D] ([D'])) The constituent element [C] is fine particles made of resin. The constituent element [D] is fine particles made of a resin having a higher elastic modulus than that of [C]. The constituent elements [C '] and [D'] are the constituent elements [C],
It refers to those derived from the constituent elements [C] and [D], respectively, which are present in the fiber-reinforced plastic obtained by curing and molding the prepreg containing [D]. At this time, the components [C '] and [D'] do not necessarily have to have the same shape as the original [C] and [D]. For example, the components [C] and [D] may It may be partially fused.

The fact that the constituent elements [C] and [D] are fine particles has the following advantages. That is, when the fine particles are mixed with the matrix resin as the component [B], they exist in a dispersed state in the matrix resin, so that the tackiness and drapability of the matrix resin are reflected as prepreg characteristics, and It becomes a prepreg with excellent properties.

As described in the section of the prior art, US Pat. No. 5,028,478, which has already been disclosed by the present inventors, discloses a technique in which resin fine particles are localized between interlayer portions of a composite material. Is shown. For the purpose of improving impact resistance while maintaining heat resistance, the example using amorphous transparent nylon fine particles has a high CAI of 53.3 ksi.
However, measurement of the peel mode interlayer toughness G _IC of unidirectional composite, there is no composite much different for a conventional epoxy resin as the matrix resin. By using thermoplastic resin fine particles having a low elastic modulus in the category of the technology, CAI can be further improved, but there is a possibility that interlayer shear strength and heat resistance of the composite material may be reduced. That is, the impact resistance, interlaminar toughness, interlaminar shear strength and heat resistance of the composite material have been mutually exclusive properties.

However, the combined use of the components [C] ([C ']) and [D] ([D']) not only shows high impact resistance, but also unexpectedly increases the interlayer toughness G. They have found that they are effective in improving the edge peel strength (EDS) of _ICs and cross-laminated boards, and can maintain high interlayer shear strength and heat resistance. Here, component [C]
([C ']) and [D] ([D']) need to have a substantial difference in the elastic modulus of the material, and this difference in the elastic modulus is usually 30 kg / mm ² or more, particularly 60 kg / mm. It is preferable that it is ² or more from the viewpoint of improvement in toughness.

[C] ([C ']) and [D]
As long as the material of ([D ′]) is a resin, it can be widely used, but particularly suitable are fine particles of a thermoplastic resin. As the thermoplastic resin used as the fine particles, the main chain includes a carbon-carbon bond, an amide bond, an imide bond, an ester bond, an ether bond, a carbonate bond, a urethane bond, a urea bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond. A thermoplastic resin having a selected bond is typical. In particular, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone , Polyaramid, polyether nitrile, and polybenzimidazole have excellent impact resistance and are suitable as the material of the fine particles used in the present invention. Among these, polyamide, polyamideimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polyethersulfone, and polysulfone are suitable for the present invention because of their high toughness and good heat resistance. The toughness of polyamide is particularly excellent, and by using a material belonging to amorphous transparent nylon, it can also have heat resistance.

Semi-IPN or semi-IPN as a component [C] ([C ']) or [D] ([D']) by a combination of a thermoplastic resin and a thermosetting resin.
The resin fine particles that can be converted are also preferable because the fine particles themselves have excellent solvent resistance and maintain the solvent resistance of the entire composite material.
Here, IPN refers to an interpenetrating polymer network.
abbreviation for “oligomer network”, which refers to a mutual intrusion network structure between cross-linked polymers, while semi-IPN refers to
It refers to an interpenetrating network structure between a crosslinked polymer and a linear polymer.

As means for making such a semi-IPN, there are a method in which a thermoplastic resin and a thermosetting resin are heated and melted, uniformly mixed, and then cooled to form a block.
After dissolving the thermoplastic resin and thermosetting resin in a common solvent and mixing them uniformly, the solvent is volatilized and removed to form a block.The thermoplastic resin and thermosetting resin were dissolved in a common solvent and made uniform. After that, spray and dry in a mist state, so-called spray drying method, after dissolving the thermoplastic resin and the thermosetting resin in a common solvent and mixing them uniformly, put them in a mist in a solvent that does not dissolve both resins and precipitate. The so-called spray reprecipitation method, a thermoplastic resin and a thermosetting resin are dissolved in a common solvent, and while the solution is stirred, a dispersion medium that is hardly compatible with the solution is gradually added, so that the solution is dispersed in the dispersion medium. There is a method in which particles are dispersed, the solvent is removed, and the particles are collected as fine particles.

The thermoplastic resin and the thermosetting resin are semi-IP
If the N-treated particles are used as fine particles, fine particles having good solvent resistance and good adhesion to the matrix resin can be obtained while maintaining the toughness of the particles themselves by selecting the composition.
However, this semi-IPN conversion may be achieved during the molding of the composite material. This is the component [C]
The composite material obtained by molding the prepreg is impact resistant,
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-modified resin fine particles is such that while the solvent resistance of the fine particles is excellent, the impact resistance of the composite material is inferior 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 sharply improved.

On the other hand, since the toughness of the thermoplastic resin fine particles used is considered to be reduced due to the semi-IPN conversion with the thermosetting resin, the impact resistance of the composite material is reduced as compared with the case where the thermoplastic resin fine particles themselves are used. However, the impact resistance tends to be unexpectedly improved in a range where the weight fraction of the thermosetting resin is small. This is considered to be due to the fact that the adhesion between the fine particles and the constituent element [B ′] as the matrix resin is improved by the semi-IPN conversion.

When the constituent element [D] ([D ']) is a fine particle in which a semi-IPN is formed by a polyamide and an epoxy resin, or is a fine particle capable of forming a semi-IPN, various characteristics of the composite material as the final product In other words, an optimum balance of impact resistance, solvent resistance, fatigue characteristics, heat resistance and the like can be obtained.

As the constituent element [D] ([D ']), thermosetting resin fine particles can also 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 component [C] ([C ′]) having a sufficiently high toughness are used in combination, the component [B ′] When combined with a matrix resin having sufficiently high toughness as a matrix resin, the presence of [D '] enables high toughness between the laminated layers even if the fineness of the fine particles of component [D] ([D']) is not high. Because a stable resin layer is formed stably, the impact resistance, interlayer toughness, and sheet edge peel strength of the composite material are greatly improved. Further, it has an advantage that it generally has higher heat resistance than thermoplastic resin fine particles and contributes to maintaining the heat resistance of the composite material. As such a thermosetting resin, a phenol resin, an epoxy resin, a maleimide resin, an unsaturated polyester resin and the like are preferably used.

The components [C] ([C ']) and [D]
The amount of ([D ']) is the component [B] ([B'])
The range of 1% by weight to 30% by weight with respect to the total resin of the components [C] ([C ']) and [D] ([D']) is suitable. If the amount is less than 1% by weight, the effect of the fine particles hardly appears. If the amount exceeds 30% by weight, mixing with the base resin becomes difficult, and the tackiness and drapability of the prepreg are greatly reduced.

In particular, while utilizing the rigidity of the component [B '] for the development of the compressive strength of the composite material, the composite material is composed of fine particles of the components [C'] and [D '] having a large elongation at break and high toughness. If you want to increase the toughness between layers, rather than 3% by weight
A smaller 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 which forms a microphase-separated structure when cured is used in combination as a matrix resin of the component [B ']. If not, surprisingly small amounts of components [C] ([C ']) and [D], for example, 5%
By using ([D ']), high impact resistance, interlayer toughness, and sheet edge peel strength can be obtained. Moreover, component [C]
A smaller amount of ([C ']) and [D] ([D']) is more preferable for maintaining heat resistance and interlaminar shear strength. A composite material in which high elastic modulus [D '] is localized in the interlaminar layer allows stable formation of a highly tough interlaminar thickness regardless of changes in curing conditions, and provides excellent impact resistance and interlaminar toughness. And contributes to giving the edge peel strength. For example, in a particularly preferred embodiment using a polyamide resin having an appropriate elastic modulus as each of the components [C] ([C ']) and [D] ([D']), a high heat resistance and an interlayer shear strength are obtained. while maintaining the interlayer toughness _{G IC} is 600 J / ^{m 2} or more and EDS express nonfibrous direction characteristic surprising such above 70 ksi. Moreover, surprisingly, the excellent impact resistance and interlayer toughness are stably exhibited regardless of the change in the molding conditions.

The combination of component [C] ([C ']) and component [D] ([D']) can be selected according to various purposes. Elastic modulus 250k
g / mm ² or less resin-based fine particles,
[D] ([D ']) is made of a resin having an elastic modulus of 140 kg / mm ² or more, and the elastic modulus of [C] ([C']) is higher than that of [D] ([D ']). When it is also low, the improvement in toughness is remarkable, which is preferable. Furthermore, the material of [C] ([C ']) has an elastic modulus of 50 kg / mm ² or more and 200 kg / mm ²
And the material of [D] ([D ']) has an elastic modulus of 1
70 kg / mm ² or more resin and [C]
When the combination of ([C ′]) elastic modulus is lower than the elastic modulus of [D] ([D ′]) and the elastic modulus of [B ′], the effect of the present invention is more remarkable. In the present invention, the elastic modulus of the resin used as the material of the constituent element [C] ([C ']) or [D] ([D']) refers to a flexural modulus measured by ASTM D790.

When only the component [C ′] having a relatively low modulus of elasticity is used in the interlayer, high impact resistance, interlayer toughness,
Although the sheet edge peel strength is given, there is a tendency that the compressive strength, particularly the compressive strength under high temperature and the interlaminar shear strength is impaired. On the other hand, when only the component [D '] having a relatively high modulus of elasticity is used in the interlayer, high compressive strength and shear strength between layers, and in some cases, high impact resistance are imparted, but interlayer toughness and board edge peeling are provided. There is a tendency that the effect of improving strength is small. Therefore, the ratio of the component [C] ([C ']) to the component [D] ([D']) can be variously selected and designed according to the use and purpose of using the composite material. Interlayer toughness,
[C] for designs that place more emphasis on the edge peel strength
([C ′]): [D] ([D ′]) = 9: 1 to 3: 7, preferably 9: 1 to 4: 6. Conversely, in a design in which the compressive strength, especially the compressive strength under high temperature and the interlaminar shear strength is more important, [C]
([C ']): [D] ([D']) = 7: 3 to 2: 8 is preferable, and 6: 4 to 3: 7 is more preferable.

The glass transition temperature of the component [D] ([D ']) is preferably 100 ° C. or higher in order to maintain the heat resistance of the composite material, and more preferably 120 ° C. or higher. The components [C ′] and [D ′] are 10
It plays a role of stably forming a resin layer of about 70 μm.

Regarding the distribution of the constituent elements [C ′] and [D ′], it is highly localized and present in the interlayer portion of the composite material, which has high impact resistance, interlayer toughness, and excellent board end peel strength. It is important to give. Particularly preferably, in a fiber-reinforced plastic in which a plurality of layers composed of the constituent element [A] and the constituent element [B] are laminated, the constituent element [C ′] is located between the layers. ] And [D '] are localized in 90% or more of the total amount.

In the present invention, as shown in FIG. 1, the “interlayer region” is a region formed at a portion where a layer composed of the component [A] and the component [B] and upper and lower layers thereof are in contact with each other. Assuming that the average thickness of each layer is t, 0.3 is 0.15 t in the thickness direction from the surface where the layers are in contact with each other.
A region having a thickness of t. When 90% or more of the constituent elements [C '] and [D'] are localized in a region having a thickness of 0.2 t, which is 0.1 t at a time in the thickness direction from the surface where the layers are in contact with each other. Is more preferable because the effects of the present invention are more remarkably exhibited.

When the above conditions are not satisfied and a large amount of components [C '] and [D'] are present deep inside the layer beyond the "interlayer region", the impact resistance and interlayer toughness of the fiber reinforced plastic are And the effect of improving EDS is small, and the compressive strength and heat resistance may be impaired.

The state of distribution of the constituent elements [C ′] and [D ′] in the composite material is evaluated as follows. First, the composite material was cut perpendicular to the lamination plane, and
Create a photograph of 200 mm x 200 mm or more by enlarging it more than twice. The photograph is taken so that the plane direction of the layer and one side of the photograph are parallel.

Using this cross-sectional photograph, first, the average layer thickness is determined. The average thickness of the layers is determined by measuring the thickness of at least five or more laminated portions on the photograph at five arbitrarily selected locations, and dividing the value by the number of the laminated layers. Next, the cross section of the same composite material was enlarged 400 times or more to 200 mm × 20 mm.
Make a photograph of 0 mm or more. Using this photograph, pay attention to one layer, and draw a line at the approximate center of that layer.

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

Therefore, the area of the constituent elements [C ′] and [D ′] in the “interlayer region” and the total area of the constituent elements [C ′] and [D ′] in the above-mentioned one-layer thickness region are reduced. By quantifying and taking the ratio, the ratio of the constituent elements [C ′] and [D ′] existing in the “interlayer region” is calculated. Here, the area quantification of the components [C '] and [D'] is obtained by cutting out all the components [C '] and [D'] existing in a predetermined region from the cross-sectional photograph and weighing the weight. Do.

The fact that the constituent elements [C ′] and [D ′] are localized and present between the laminated layers of the composite material means that the constituent elements [C] and [D] can be replaced by a prepreg before molding. Is localized near the prepreg surface. In particular, components [C] and [D]
90% or more exists within a depth of 30% of the thickness of the prepreg from the prepreg surface, this condition is deviated and the components [C] and [D] are deeper inside the prepreg. In addition, the impact resistance, interlayer toughness and peel strength of the sheet edge of the composite material are remarkably excellent. When 90% or more of [C] and [D] are localized within a range of a depth of 20% of the prepreg thickness from the prepreg surface, a more remarkable effect appears, and a depth of 10% is obtained. It is more preferable to localize within the range. As such a localizing means, a known means disclosed in, for example, Japanese Patent Application Laid-Open No. 1-26651 described later can be employed.

The components [C] in the prepreg,
The distribution of [D] is optimal if it is similarly localized on both sides of the prepreg, since it can be freely laminated regardless of the front and back of the prepreg. However, even in a prepreg in which the fine particles have the same distribution on only one side of the prepreg, the same effect can be obtained if care is taken so that the fine particles always come between the prepregs when laminating the prepregs. The present invention also includes a distribution in which the fine particles [C] and [D] are biased on only one side.

Evaluation of the distribution state of the constituent elements [C] and [D] in the prepreg is performed as follows. First,
The prepreg is tightly sandwiched between two smooth support plates, and the temperature is gradually increased over a long period of time to cure. The important thing at this time is to gel at as low a temperature as possible. If the temperature is suddenly increased before gelation, the resin in the prepreg flows and the fine particles move, so that accurate evaluation of the distribution state in the prepreg cannot be performed.

After the gelling, the temperature is gradually increased over time to harden the prepreg. The cross section of the cured prepreg is enlarged 200 times or more using the cured prepreg.
Take a picture of at least 200 mm x 200 mm.

First, an average thickness of the prepreg is determined by using the photograph of the cross section. The average thickness of the prepreg is measured at at least five locations selected arbitrarily on the photograph, and the average is taken. Next, a line is drawn parallel to the surface direction of the prepreg at a position 30% of the thickness of the prepreg from the surface in contact with both support plates. The area of the fine particles existing between the surface in contact with the support plate and the 30% parallel line is quantified on both sides of the prepreg, and the total area of the fine particles existing over the entire width of the prepreg is quantified, and the ratio is determined. Thus, the ratio of the fine particles present within a depth of 30% from the surface of the prepreg is calculated. The determination of the area of the fine particles is performed by cutting out all the fine particles present in a predetermined region from the cross-sectional photograph and weighing them. In order to eliminate the influence of the partial distribution variation of the fine particles, this evaluation is performed over the entire width of the obtained photograph, and the same evaluation is performed for five or more randomly 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 and observed. Although the microscope can be observed with an optical microscope, a scanning electron microscope may be more suitable for observation depending on the staining method.

Components [C] ([C ']), [D]
The shape of ([D ']) is not limited to a spherical shape. Of course, it may be spherical, but it may be in any shape in various shapes such as fine powder obtained by pulverizing a resin mass or fine particles obtained by spray drying or reprecipitation.
In addition, even if it is a milled fiber shape where the fiber is cut short,
Needles and whiskers may be used. In particular, in the fiber-reinforced plastic after molding, the shape may be changed from the shape before molding, and the particles may be somewhat fused to be continuous. However, the viscosity of the resin composition containing [C] and [D] is lower when [C] and [D] are spherical than when they are non-spherical, so that a prepreg can be easily produced and is preferable.

The size of the fine particles is represented by a particle size, and the particle size in this case means a volume average particle size determined by a centrifugal sedimentation velocity method or the like. Component [C] ([C ']),
The size of [D] ([D ']), when it becomes a composite material,
It does not have to be large enough to significantly disturb the arrangement of the reinforcing fibers.
When the particle size exceeds 100 μm, there is a disadvantage that the arrangement of the reinforcing fibers is disturbed, and the physical properties of the composite material are deteriorated because the layers of the composite material obtained by lamination are unnecessarily thick. In order to form a more appropriate interlayer thickness, [C]
([C ']) or [D] ([D']) has a particle size of 3-7.
The range of 0 μm is good.

A method for producing a prepreg in which such components [C] and [D] are localized on the surface is described in JP-A-1-26651 and JP-A-63-170427.
As disclosed in JP-A-63-170428, a method of adhering constituents [C] and [D] to the surface of a prepreg made of a reinforcing fiber and a matrix resin prepared in advance, and a method of forming constituents [C ], [D] is uniformly mixed in a matrix resin, and in the process of impregnating the reinforcing fibers, a method of localizing on the prepreg surface by a filtration phenomenon due to a fiber gap, a method of impregnating the reinforcing fibers with a part of the matrix resin. Then, a method may be employed in which the primary prepreg is first produced, and then a film of the remaining matrix resin containing the components [C] and [D] at a high concentration is attached to the surface of the primary prepreg.

[0081]

The present invention will be described in more detail with reference to the following examples. Example 1 A one-way prepreg having the following structure was manufactured. First, the following A
A prepreg having a weight fraction of 21% of a resin consisting of C and D was prepared, and a resin film in which a blend resin of C, D and B was thinly applied on release paper was adhered to both surfaces. The following parts by weight of C and D 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 (manufactured by Sumitomo Chemical Co., Ltd., ELM434) ... 70 weight Part 2 Bisphenol A type epoxy resin (Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) 10 parts by weight 3 Bisphenol F type epoxy resin (Epiclon 830, manufactured by Dainippon Ink Industries, Ltd.) 20 parts by weight 44,4'-diaminodiphenylsulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) 45 parts by weight C nylon 12 fine particles (SP-500, manufactured by Toray Industries, Inc.) 6 parts by weight D Fine particles having an average particle diameter of 22 μm obtained by freeze-pulverizing amorphous transparent nylon (Trogamido-T manufactured by Diminat Novell)・ 8 parts by weight

When the flexural modulus of the resin used as the material of the constituent elements [C] and [D] was measured in accordance with ASTM D790, nylon 12 was 110 kg / mm ² ,
The amorphous transparent nylon had a weight of 195 kg / mm ² .

The weight fraction of the resin in the prepreg was 35%. The resin amount per unit area was 103 g / m ² , and the carbon fiber amount per unit area was 191 g / m ² .
This prepreg was sandwiched between two smooth Teflon plates, gradually heated to 150 ° C. for two weeks and cured, and its cross section was observed and a micrograph was taken. When the amount of fine particles existing 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 prepregs were laminated in a quasi-isotropic configuration ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ S), and molded by ordinary autoclave at 180 ° C. for 2 hours. The test was performed under a pressure of 6 kgf / cm ² .

The cross section of the molded product was polished, and the cross section was observed with a microscope. The two types of fine particles were present separately from the matrix resin in the interlayer region. Evaluation of the average thickness of the layer is 5
A photograph magnified 0 times was taken, and an average of 5 points was 189 μm. Next, the ratio of fine particles present in the interlayer region was evaluated using five cross-sectional photographs of an arbitrary portion magnified 400 times and found to be 98% (the width of the interlayer region was 43.7 μm). I was

This pseudo isotropic hardened plate was 150 mm long and 1 mm wide.
Cut to 00mm and center around 1500 inch-pounds /
After giving an impact of the falling weight of inch, the damage area was measured by an ultrasonic flaw detector M400B manufactured by Canon / Horonics, Inc., and it was 0.7 inch ² . ASTM
As a result of performing a compression test according to D-695, 49 ksi
Showed the residual compressive strength.

[0086] Twenty-four prepregs were laminated in one direction to form a cured plate. It was cut out to 80 mm in length (fiber direction) and 12.7 mm in width (fiber perpendicular direction), and two cuts were made in the thickness direction from the front to the center and from the back to the center (FIG. 2). The interval 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 10.8 ksi.

[0088] Further, prepreg in one direction to a laminate of 20 layers peeled was measured interlayer toughness of composite modes toughness G _IC of was 630J / m 2 ^(double cantilever beam method).

[0089] In the configuration of (± 25 / ± 25/90 ) s 10
A tensile test was performed using the cured plate laminated and formed on the layer, and the strength at which plate edge peeling was initially measured, that is, EDS was 65.3 ksi.

Using a cured plate formed by laminating six layers of prepregs in one direction and molding them, absorb 82% water in hot water (72 ° C.) for 2 weeks.
It was 185 ksi when the compressive strength in ° C was calculated | required according to SACMA SRS1-88.

Example 2 A one-way prepreg having the following structure was manufactured. For the production of prepreg, first, a prepreg having the following resin A and B having a weight fraction of 21% is prepared in advance, and a resin film obtained by thinly applying a blended resin of C, D and B on a release paper is attached to both surfaces thereof. I went by putting on. The following parts by weight of C and D 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 (Epicoat 828 manufactured by Yuka Shell Epoxy Co., Ltd.) 20 parts by weight 3 Bisphenol F type epoxy resin (Epiclon 830 manufactured by Dainippon Ink Industries, Ltd.) 40 parts by weight 4 4,4'-diaminodiphenyl sulfone (Sumicure S manufactured by Sumitomo Chemical Co., Ltd.) 42 parts by weight 5 polyether sulfone (5003P manufactured by Mitsui Toatsu Co., Ltd.) 10 parts by weight C Fine particles of nylon 12 (SP-500, manufactured by Toray Industries, Inc.) 6 parts by weight D Polyamideimide (Amoco Fine .... 8 parts by weight of the manufactured Torlon 4000T) average particle size 23μm obtained by freeze-grinding the

When the flexural modulus of the resin used as the material of the constituent elements [C] and [D] was measured in accordance with ASTM D790, nylon 12 was 110 kg / mm ² ,
Polyamide imide was 470 kg / mm ² .

The weight fraction of the 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.}
This prepreg was sandwiched between two smooth Teflon plates, gradually heated to 150 ° C. for two weeks and cured, and its cross section was observed and a micrograph was taken. When the amount of the fine particles existing in the range from the prepreg surface to a depth of 30% of the prepreg thickness was evaluated, the value was 95%, and the fine particles were sufficiently localized near the prepreg surface.

Next, 24 prepregs were laminated in a quasi-isotropic configuration ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ s), and molded by ordinary autoclave at 180 ° C. for 2 hours. The test was performed under a pressure of 6 kgf / cm ² .

The cross section of the molded product was polished, and the cross section was observed with a microscope. The two types of fine particles were present separately from the matrix resin in the interlayer region. Evaluation of the average thickness of the layer is 5
A photograph magnified to 0 times was taken, and an average of 5 points was 191 μm. Next, the ratio of fine particles present in the interlayer region was evaluated using five cross-sectional photographs of an arbitrary portion magnified 400 times and found to be 96% (the width of the interlayer region was 50.7 μm). I was

The quasi-isotropic hardened plate was 150 mm long and 1 mm wide.
Cut to 00mm and center around 1500 inch-pounds /
After giving an impact of a falling weight of inches, the damage area was measured with an ultrasonic flaw detector M400B manufactured by Canon / Horonics, Inc., and it was 1.0 inch2. ASTM
As a result of performing a compression test according to D-695, 48 ksi
Showed the residual compressive strength.

[0097] Further, prepreg in one direction to a laminate of 20 layers peeled was measured interlayer toughness of composite modes toughness G _IC of was 600 J / m 2 ^(double cantilever beam method).

[0098] In the configuration of (± 25 / ± 25/90 ) S 10
A tensile test was performed using the cured plate laminated and formed on the layer, and the strength at which sheet edge peeling occurred, that is, the EDS was first determined to be 64.8 ksi.

Using a cured plate obtained by laminating and forming 24 layers of prepreg in one direction, the compression interlaminar shear strength (CILS) was found to be 11.8 ksi. Using a hardened plate formed by laminating six layers of prepreg in one direction and molding, warm water (72
C)) and the compressive strength at 82 ° C after water absorption was determined.
It was 190 ksi.

Example 3 Part A: Synthesis of Reactive Polyimide Oligomer A nitrogen inlet, a thermometer, a stirrer, and a dehydration trap equipped with a separable flask having a capacity of 3000 ml and 208 g (0 .75 mol) of 1,3-bis (3-aminophenoxy) benzene (APB), 33 g
(0.094 mol) of 9'9'-bis (4-aminophenyl) fluorene (FDA), 122 g (0.094 mol)
mol) NH-equivalent 650 amino-terminated dimethylsiloxane (BY-16853, commercially available from Toray Silicone Co., Ltd.)
With 2000 ml of N-methyl-2-pyrrolidone (NM
P) was dissolved by 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 at 160 ° C. to obtain about 30 ml of water. After cooling, the reaction mixture 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 4900 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 a siloxane skeleton and the presence of an amine terminal were confirmed by NMR spectrum and IR
It could be confirmed from the spectrum.

Part B: Preparation of Resin and Measurement of Physical Properties of Constituent B In a beaker, 25 parts of the siloxane polyimide oligomer of Part A and a phenol novolak type epoxy resin (Epicoat 154, manufactured by Yuka Shell Epoxy Co., Ltd.) 40
30 parts of a bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat 825) and 30 parts of a bisphenol F type epoxy resin (manufactured by Dainippon Ink Industries, Ltd., Epicron 830) were weighed. 120
The oligomer was dissolved in the epoxy resin by heating at 2 ° C. for 2 hours. Then, 4,4'-diaminodiphenyl sulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) was added to 34
The mixture was mixed at 140 ° C. for 10 minutes and dissolved.

After a vacuum pump was connected to the container and the inside of the container was degassed under vacuum, a mold subjected to a release treatment in which the contents were preheated to 120 ° C. in advance (the size of the space was 120 × 120)
× 3 mm). A curing reaction was performed in an oven at 130 ° C. for 2 hours and at 180 ° C. for 2 hours to prepare a cured resin plate having a thickness of 3 mm.

The Tg of the obtained cured resin was 201 ° C. A sample was cut out of the from here is 390J / ^{m 2} was measured fracture strain energy release rate _{G IC,} a flexural modulus of 350 kg / mm ^2.

When the polished surface of the cured resin is stained with osmic acid and the reflected electron image is observed with a scanning electron microscope, basically, the two phases together form a continuous phase, and the dispersed phase of each of the other phases is contained therein. A complex microphase-separated structure in which is present was observed. Further, when the same visual field was subjected to elemental analysis using an X-ray microanalyzer, it was found that the silicon element was densely distributed in a high-contrast phase that appeared 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. For the production of prepreg, first, a prepreg having the following resin A and B having a weight fraction of 21% is prepared in advance, and a resin film obtained by thinly applying a blended resin of C, D and B on a release paper is attached to both surfaces thereof. I went by putting on. The following parts by weight of C and D 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 Phenol novolak type epoxy resin (Epicoat 154, manufactured by Yuka Shell Epoxy Co., Ltd.) 40 parts by weight 2 bisphenol A type epoxy resin (Eicoat 825, manufactured by Yuka Shell Epoxy Co., Ltd.) 30 parts by weight 3 bisphenol F type epoxy resin (Epiclon 830, manufactured by Dainippon Ink Industries, Ltd.) ... 30 parts by weight 4 4,4'-diaminodiphenylsulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) ... 34 parts by weight 5 Siloxane polyimide oligomer described in Part A. ... 25 parts by weight C Nylon 12 fine particles (SP-500, manufactured by Toray Industries, Inc.) 6 parts by weight D Amorphous transparent nylon (manufactured by Deminat Novell) Rogamido T) fine .... 6 parts by weight of the average particle diameter 22μm obtained by freeze-grinding the

When the flexural modulus of the resin as the material of the constituent elements [C] and [D] was measured in accordance with ASTM D790, nylon 12 was 110 kg / mm ² ,
The amorphous transparent nylon had a weight of 195 kg / mm ² .

The weight fraction of the resin in the prepreg was 36.7.
%Met. 110 g / resin per unit area
m ² , the amount of carbon fiber per unit area was 190 g / m ² . This prepreg was sandwiched between two smooth Teflon plates, gradually heated to 150 ° C. for two weeks and cured, and its 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 sufficiently localized on the prepreg surface.

Next, 24 prepregs were laminated in a quasi-isotropic configuration ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ s) and molded in a normal autoclave at 180 ° C. for 2 hours at 6 kgf. / Cm ² .

The cross section of the molded product was polished, and the cross section was observed with a microscope. The two types of fine particles were present separately from the matrix resin in the interlayer region. Evaluation of the average thickness of the layer is 5
A photograph magnified 0 times was taken, and an average of 5 points was 190 μm. Next, the ratio of the fine particles present in the interlayer region was evaluated using five cross-sectional photographs of an arbitrary portion magnified 400 times and found to be 99% (the width of the interlayer region was 30.6 μm). I was

This pseudo isotropic hardened plate is 150 mm long and 1 mm wide.
Cut to 00mm and center around 1500 inch-pounds /
After giving an impact of a falling weight of inches, the damage area was measured with an ultrasonic flaw detector M400B manufactured by Canon / Horonics, Inc., and it was 0.6 inch ² . ASTM
As a result of performing a compression test according to D-695, 55.2 k
The residual compressive strength of si was shown. Table 1 shows the results of the same post-impact compression test performed on the cured plate with different molding conditions. Physical properties were stable irrespective of molding conditions.

[0112] Further, prepreg in one direction to a laminate of 20 layers peeled was measured interlayer toughness of composite modes toughness G _IC of was 690J / m 2 ^(double cantilever beam method).

[0113] In the configuration of (± 25 / ± 25/90 ) S 10
A tensile test was performed using the cured plate laminated and formed on the layer, and the strength at which plate edge peeling was initially caused, that is, the EDS was determined to be 76.9 ksi.

The compression interlaminar shear strength (CILS) was determined to be 10.7 ksi using a cured plate obtained by laminating and forming 24 layers of prepreg in one direction. Using a cured plate formed by laminating six layers of prepregs in one direction and using hot water (7
When the compressive strength at 82 ° C. after water absorption in (2 ° C.) was determined, it was 183 ksi.

Example 4 Component C was 9 parts by weight of fine particles having an average particle size of 22 μm obtained by freeze-pulverizing amorphous transparent nylon (Trogamido-T manufactured by Deminat Novell), and Component D was polyamideimide. (Amoko's Torlon 400
0T) obtained by freeze-pulverization of fine particles 4 having an average particle size of 23 μm.
The same procedure as in Example 1 was repeated, except that the parts were replaced by parts by weight.

When the flexural modulus of the resin as the material of the constituent elements [C] and [D] was measured in accordance with ASTM D790, the amorphous nylon 12 was 195 kg / m2.
m ² , and the amount of polyamideimide was 470 kg / mm ² .

From the prepreg surface to the prepreg thickness of 30
When the amount of the fine particles existing in the range up to the% depth was evaluated, the value was 100%, and the fine particles were sufficiently localized on the prepreg surface.

Next, the cross section of a molded product obtained by laminating 24 prepregs in a pseudo isotropic configuration ((+ 45 ° / 0 ° / −45 ° / 90 °) ₃ s) is polished, and the cross section is observed with a microscope. As a result, the two types of fine particles were present separately from the matrix resin in the interlayer region. The average thickness of the layer was 190 μm. The ratio of the fine particles present in the interlayer region was 100%, and the particles were localized between the layers.

[0119] The after giving falling weight impact 1500 inch pounds / inch in the center of the quasi-isotropic cured plate was 0.8Inch ² was measured damage area. Then, as a result of a compression test, a high residual compressive strength of 49.5 ksi was shown.

[0120] Further, prepreg in one direction to a laminate of 20 layers peeled was measured interlayer toughness of composite modes toughness G _IC of was 480J / m 2 ^(double cantilever beam method).

[0121] In the configuration of (± 25 / ± 25/90 ) S 10
A tensile test was performed using the cured plate formed by laminating the layers and molded, and the strength at which sheet edge peeling occurred, that is, the EDS was first determined to be 63.4 ksi.

The compression interlaminar shear strength (CILS) was determined to be 12.3 ksi using a cured plate formed by laminating and forming 24 layers of prepreg in one direction. Using a cured plate formed by laminating six layers of prepregs in one direction and using hot water (7
The compressive strength at 82 ° C. after water absorption in (2 ° C.) was 188 ksi.

Comparative Example 1 The same procedure as in Example 1 was repeated, except that the addition amount of the component C was increased to 14 parts by weight instead of removing the component D. When the amount of the fine particles present in the range from the prepreg surface to the 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 a molded product obtained by laminating 24 prepregs in a pseudo isotropic configuration ((+ 45 ° / 0 ° / −45 ° / 90 °) ₃ s) was polished, and the cross section was observed with a microscope. As a result, the two types of fine particles were present separately from the matrix resin in the interlayer region. The average thickness of the layer was 190 μm. The ratio of the fine particles existing in the interlayer region was 99%, and the particles were localized between the layers.

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

However, when a cured plate obtained by laminating 24 prepregs in one direction and molding was used to determine CILS,
It was 7.5 ksi, which was significantly inferior to the example. Further, using a cured plate formed by laminating six layers of prepregs in one direction and forming the cured plate at 82 ° C. after absorbing water in warm water (72 ° C.) for 2 weeks.
Was found to be 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 component D was increased to 14 parts by weight instead of removing the component C. When the amount of the fine particles present in the range from the prepreg surface to the depth of 30% of the prepreg thickness was evaluated, the value was 97%, and the fine particles were sufficiently localized on the prepreg surface.

Next, the cross section of a molded product obtained by laminating 24 prepregs in a pseudo isotropic configuration ((+ 45 ° / 0 ° / -45 ° / 90 °) ₃ s) is polished, and the cross section is observed with a microscope. As a result, the two types of fine particles were present separately from the matrix resin in the interlayer region. The average thickness of the layer was 190 μm. The ratio of the fine particles present in the interlayer region was 95%, and the particles were localized between the layers.

[0129] The after giving falling weight impact 1500 inch pounds / inch in the center of the quasi-isotropic cured plate was 0.1Inch ² was measured damage area. Subsequently, a compression test was performed, and as a result, a residual compressive strength of 44 ksi was shown.

The compression interlaminar shear strength (CILS) of a cured plate formed by laminating 24 layers in one direction was determined to be 11.0.
ksi, which was equivalent to the example. However, toughness G _IC of peel mode although prepreg was 20 layers laminated in one direction is 250 J / m 2 ^(da pull cantilever beam method), was inferior considerably compared with Example. When the EDS of the cured plate obtained by laminating 10 layers with the composition of (± 25 / ± 25/90) _S and obtaining it was 38.5 k
si, which was significantly inferior to the examples.

[0131]

EFFECT OF THE INVENTION The prepreg according to the present invention has a high interlaminar shear strength when heated and formed into a composite material while securing tackiness and drapability as a prepreg, and has excellent high impact resistance and interlaminar toughness. Having. Further, the occurrence of peeling at the edge of the laminate when the laminate is pulled is significantly suppressed, and the fatigue resistance is excellent. Moreover, the high physical properties provide an excellent fiber reinforced plastic which stably develops despite changes in molding conditions such as a heating rate, a curing temperature, and a pressure.

[0132]

[Table 1]

[Brief description of the drawings]

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

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

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-104625 (JP, A) JP-A-1-104624 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/24

Claims (24)

(57) [Claims] 1. A prepreg comprising the following components [A], [B], [C] and [D], wherein the components [C] and [D] are localized on the surface. . [A]: Reinforcing fiber composed of long fiber [B]: Thermosetting resin composition [C]: Fine particles made of resin [D]: Fine particles made of resin having a higher elastic modulus than [C] 2. The method according to claim 1, wherein 90% or more of the constituent elements [C] and [D] are localized within a depth of 30% of the thickness of the prepreg from the prepreg surface. The prepreg described. 3. Component (C) is polyamide, polycarbonate, polyacetal, polyphenylene oxide,
From polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, polyaramid, polyethernitrile and polybenzimidazole The prepreg according to claim 1 or 2, wherein the material is a resin selected from the group consisting of: 4. The composition according to claim 1, wherein component [D] is polyamide, polycarbonate, polyacetal, polyphenylene oxide,
From polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, polyaramid, polyethernitrile and polybenzimidazole The prepreg according to any one of claims 1 to 3, wherein the material is a resin selected from the group consisting of: 5. The prepreg according to claim 1, wherein the constituent elements [C] and / or [D] are made of a thermosetting resin and a semi-IPNized thermoplastic resin. 6. The material according to claim 1, wherein the constituent element [D] is made of at least one thermosetting resin selected from the group consisting of a phenol resin, an epoxy resin, a maleimide resin, and an unsaturated polyester resin. The prepreg described. 7. The method according to claim 1, wherein the constituent elements [C] and [D] have physical properties in the following ranges.
The prepreg according to the item. [C]: Fine particles made of a resin having an elastic modulus of 250 kg / mm ² or less [D]: Fine particles made of a resin having an elastic modulus of 140 kg / mm ² or more 8. The thermosetting resin in the component [B] comprises at least one thermosetting resin of the group consisting of an epoxy resin, a cyanate resin and a bismaleimide resin. The prepreg according to any one of the preceding claims. 9. A thermosetting resin composition in which a constituent element [B] is a mixed or dissolved thermoplastic resin selected from polyethersulfone, polysulfone, polyimide, polyetherimide and polyimide having a phenyltrimethylindane structure. Claim 1 characterized by the fact that
8. The prepreg according to any one of 8 above. 10. The prepreg according to claim 1, wherein the constituent element [B] is a thermosetting resin composition in which a polyimide containing a cycloxane skeleton is mixed or dissolved. 11. 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. 12. The prepreg according to claim 1, wherein the constituent element [A] is a carbon (graphite) fiber. 13. The following components [A], [B '],
[C '] and [D'], and the constituent elements [C '],
A fiber-reinforced plastic, wherein [D '] is localized in the interlayer portion. [A]: Reinforced fiber composed of long fiber [B ']: Thermosetting resin composition [C']: Fine particles made of resin [D ']: Made of resin having higher elastic modulus than [C'] Fine particles 14. The ninth of the constituent elements [C ′] and [D ′]
14. The fiber reinforced plastic according to claim 13, wherein 0% or more is localized in the interlayer portion. 15. The constituent element [C ′] is polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polysulfone, or polysulfone. 15. The fiber reinforced plastic according to claim 13, wherein a resin selected from the group consisting of ether sulfone, polyether ketone, polyether ether ketone, polyaramid, polyether nitrile, and polybenzimidazole is used as a material. 16. The constituent element [D '] is polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polyimide, polysulfone, or polysulfone. The fiber according to any one of claims 13 to 15, wherein a resin selected from the group consisting of ether sulfone, polyether ketone, polyether ether ketone, polyaramid, polyether nitrile, and polybenzimidazole is used as a material. Reinforced plastic. 17. The fiber-reinforced plastic according to claim 13, wherein the constituent elements [C ′] and [D ′] are made of a thermoplastic resin having an amide bond. 18. The component [C ′] and / or [D ′] is made of a thermosetting resin and a semi-IPN thermoplastic resin.
The fiber reinforced plastic as described. 19. The material according to claim 13, wherein the constituent element [D ′] is made of at least one thermosetting resin of the group consisting of an unsaturated polyester resin, a phenol resin, an epoxy resin and a maleimide resin. 15. The fiber-reinforced plastic according to 14. 20. The fiber-reinforced plastic according to any one of claims 13 to 19, wherein the constituent elements [C ′] and [D ′] have the following physical properties. [C ′]: Fine particles made of resin having an elastic modulus of 250 kg / mm ² or less [D ′]: Fine particles made of resin having an elastic modulus of 140 kg / mm ² or more 21. The thermosetting resin according to claim 13, wherein the thermosetting resin of the component [B ′] is at least one thermosetting resin selected from an epoxy resin, a cyanate resin and a bismaleimide resin. The fiber-reinforced plastic according to any one of the preceding claims. 22. A thermosetting resin cured product containing a thermoplastic resin selected from the group consisting of polyethersulfone, polysulfone, polyimide, polyetherimide and polyimide having a phenyltrimethylindane structure. The fiber-reinforced plastic according to any one of claims 13 to 12, characterized in that: 23. The fiber-reinforced plastic according to any one of claims 13 to 20, wherein the constituent element [B '] is a cured thermosetting resin containing polyimide containing a silicon element. 24. The fiber-reinforced plastic according to claim 13, wherein the constituent element [A] is a carbon (graphite) fiber.