JPH0741576A - Prepreg and fiber-reinforced resin - 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) of a resin, and fine particles (D) of a resin having a glass transition temperature (Tg) higher than that of the resin of component C. 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 resin which 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 referred to as 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 heat resistance, handleability, and other characteristics in order 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 61-22
Even when an oligomer having a reduced molecular weight is added as in JP-A-8016, 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 heat resistance decreases as the content of the elastomer increases, and the content of the elastomer decreases. And the effect of improving impact resistance 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 heat resistance of the composite material and also lowers the interlaminar shear strength.

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 the compressive strength after impact (CAI) in the examples of JP-A-3-26750, the degree of impact resistance cannot be evaluated, but the elastomer in the particles lowers the heat resistance. it is conceivable that.

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 low heat resistance within the scope of the 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 superior to those of the above-mentioned prior examples while maintaining high heat resistance and interlaminar shear strength, 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 resin obtained from the prepreg for giving a composite material having a significantly high viscosity.

[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 made of resin [D]: Fine particles made of resin having a higher Tg than [C]

The fiber-reinforced resin 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 resin is characterized in that the constituent elements [C ′] and [D ′] are localized in the laminated interlayer portion. [A]: Reinforcing fiber consisting of long fibers [B ']: Cured thermosetting resin [C']: Fine particles made of resin [D ']: Made of resin having higher Tg than [C'] Fine particles

(Explanation 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 generally used as an advanced composite material and having good heat resistance and tensile strength. For example, the reinforcing fibers include carbon fibers,
Examples thereof include graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, boron fiber, tungsten carbide fiber, and glass fiber. 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, carbon fibers and graphite fibers may be used by mixing with other reinforcing fibers. 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, the arrangement in which the 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) arrangement that is easy to handle. Are also suitable for the present invention.

(Explanation of Components [B] and [B '])
The element used as the constituent element [B] in the present invention is a thermosetting resin composition, and [B ′] is a thermosetting resin cured product obtained by curing [B]. 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] and the constituent element [B '], is cured by heat or energy from the outside such as light or electron beam, and is at least partially a three-dimensional cured product. The resin forming the is preferably used.

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. Especially amines,
An epoxy resin having a precursor having a compound having a carbon-carbon double bond as a phenol is preferred. Specifically, as an epoxy resin having an amine as a precursor, tetraglycidyl diaminodiphenylmethane, triglycidyl-p-
Aminophenol, triglycidyl-m-aminophenol, various isomers of triglycidylaminocresol,
As the epoxy resin having phenols as a precursor, 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, and a compound having a carbon-carbon double bond are used. Examples of the epoxy resin used as the precursor include alicyclic epoxy resins and the like, but are not limited to these. 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 curing agents can be used as appropriate, but compounds having an amino group, an acid anhydride group, and an azide group are particularly 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 they have poor heat resistance as compared with diaminodiphenyl sulfone, they have a tensile elongation. It has excellent properties and is selected according to the application.

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. In particular, mixing a small amount of elastomer is preferable because it improves the toughness of the resin.

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. A resin, a resin having a vinyl terminal, and a resin having an allyl terminal are 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 example of a curing agent having an amino group, and examples of a 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 a 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. The bismaleimide and the cyanate ester are usually 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 constituent element [B] and the constituent element [B ']. As the terminal reactive group, nadiimide group, acetylene group, benzocyclobutene group and the like are preferable.

The thermosetting resin in component [B] and component [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 constituent element [B] and the constituent element [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. Here, the thermoplastic resin component refers to a thermoplastic resin widely recognized in the industrial field, but belongs to a so-called engineering plastic of an aromatic type because it does not impair the original high heat resistance and high elastic modulus of the thermosetting resin. The thing is preferable as this thermoplastic resin. That is, an aromatic polyimide skeleton, an aromatic polyamide skeleton, an aromatic polyether skeleton, an aromatic polysulfone skeleton, an aromatic polyketone skeleton, an aromatic polyester skeleton, an aromatic polycarbonate skeleton, and a thermosetting resin-soluble high heat resistance. A typical example is a thermoplastic resin, and specific examples thereof include polyether sulfone, polysulfone, polyimide, polyether imide, 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 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 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 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 ′, Aromatic tetracarboxylic acid dianhydrides such as 4,4′-diphenyl ether tetracarboxylic acid dianhydride can be mentioned.

Preferred examples of the diamino compound include diaminodiphenylmethane, metaphenylenediamine, paraphenylenediamine, diaminodiphenyl ether, diaminodiphenyl sulfone, 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 having a chain compatible with the thermosetting resin and a chain incompatible with the thermosetting resin. It is particularly preferable to use the combination 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 a chain as a block 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 an effect of excellent tackiness and drapeability. From another perspective, the component [B]
There is less restriction on the amount of thermoplastic resin to be added, and a large amount can be introduced into the resin system without impairing tackiness, which is advantageous for improving 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 previously dissolved in the uncured thermosetting resin component.
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.

Since the phase containing the thermoplastic resin as a main component has a microphase-separated structure in which a continuous phase is at least partially formed, a resin cured product having high elasticity and high toughness can be 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 thermosetting 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 _i and crack growth of the sample thickness t for crack extension distance a _i compliance C by the following equation.

G _IC = P ² (ΔC / Δa _i ) / 2t

Here, the compliance C is defined by C = δ / P by the crosshead displacement amount δ when a crack occurs and the cracking load P.

(Description of Component [C] ([C ']) and [D] ([D'])) Component [C] is fine particles made of resin. Component [D] is T than [C]
It is a fine particle made of a high g resin. Further, 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 that time, the constituent elements [C ′] and [D ′] do not necessarily have to have the same shape as the original [C] and [D]. For example, the constituent elements [C] and [D] may be the same as or different from each other. It may be partially fused.

The fine particles of the constituent elements [C] and [D] have the following advantages. That is, if the particles are fine particles, since they exist 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 prepreg characteristics, It becomes a prepreg with an excellent surname.

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 fine thermoplastic resin particles having low heat resistance within the scope of the technology, but the heat resistance and interlaminar shear strength of the composite material may be reduced. That is, impact resistance, interlaminar toughness and heat resistance, and interlaminar shear strength of the composite material have hitherto been contradictory properties.

However, by using the constituent elements [C] ([C ']) and [D] ([D']) together, not only a high impact resistance is exhibited, but, surprisingly, the interlayer toughness G _IC and They have found that they have the effect of improving the edge peel strength (EDS) of the crossed laminate, maintain high heat resistance, and do not impair the interlaminar shear strength. Here, the components [C] ([C ']) and [D] ([D']) are the Tg of the material.
However, it is preferable that the difference in Tg is usually 40 ° C. or higher, especially 80 ° C. or higher from the viewpoint of improving the toughness.

Components [C] ([C ']) and [D]
If the material of ([D ′]) is a resin, it can be widely used, but particularly suitable are fine particles of a thermoplastic resin. The thermoplastic resin used as fine particles, from the main chain, carbon-carbon bond, amide bond, imide bond, ester bond, ether bond, carbonate bond, urethane bond, urea bond, thioether bond, sulfone bond, imidazole bond, 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, polyetherether Ketones, polyaramids, polyether nitriles, and polybenzimidazoles have excellent impact resistance and are suitable as a material for 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 they have high toughness and good heat resistance. The toughness of horiamide is particularly excellent, and heat resistance can be provided by using a material belonging to amorphous transparent nylon.

Semi-IPN or semi-IPN obtained by combining a thermoplastic resin and a thermosetting resin as the component [C] ([C ']) or [D] ([D']).
The resin fine particles that can be made into fine particles are also preferable because the fine particles themselves have excellent solvent resistance and maintain the solvent resistance of the entire composite material.
Here, the IPN is an interpenetrating polymer network (Interpenetrating P
Polymer Network) is an abbreviation for an interpenetrating network structure of crosslinked polymers, while a semi-IPN is
An interpenetrating network structure of a crosslinked polymer and a linear polymer.

As 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 of 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 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 rapidly improved.

On the other hand, since it is considered that the toughness of the thermoplastic resin fine particles to be used is changed to semi-IPN with the thermosetting resin, 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 property between the fine particles and the constituent element [B ′] which is the matrix resin is improved by the semi-IPN formation.

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 capable of forming a semi-IPN, various properties of the final target composite material are obtained. That is, it is possible to obtain the one having the optimum balance of impact resistance, solvent resistance, fatigue property, heat resistance and the like.

As the constituent element [D] ([D ']), thermosetting resin fine particles can be used. In this case, the toughness of the fine particles themselves is lower than that of the thermoplastic resin,
When the fine particles of the constituent element [C] ([C ′]) having sufficiently high toughness are used in combination, and further when combined with the matrix resin of the constituent element [B ′] having sufficiently high toughness, the composition is Even if the toughness of the fine particles of the element [D] ([D ']) is not great, the presence of [D'] allows a highly tough resin layer to be stably formed between the laminated layers, so that the impact resistance of the composite material is improved. Properties, interlayer toughness, and plate edge peel strength 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 resin, maleimide resin, unsaturated polyester resin and the like are preferably used.

Components [C] ([C ']) and [D]
The component [B] ([B ']) is the amount of ([D'])
The range of 1% by weight to 50% by weight 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 50% by weight, it becomes difficult to mix with the base resin, and the tackiness and drapeability of the prepreg are significantly deteriorated.

In particular, the composite material is composed of fine particles of the constituent elements [C '] and [D'] which have a large fracture elongation and a high toughness, while the rigidity of the constituent element [B '] is utilized to develop the compressive strength of the composite material. If the toughness between layers is rather 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 that forms a microphase-separated structure when cured is used in combination as a matrix resin of the constituent element [B ']. If the amount of the component [C] ([C ']) and [D] ([D']) is surprisingly small, for example, 5%, high impact resistance, interlaminar toughness,
Plate edge peel strength can be obtained. Moreover, if the amounts of the constituent elements [C] ([C ′]) and [D] ([D ′]) used are small, it is more preferable for maintaining heat resistance and interlayer shear strength. The composite material in which [D '] with a high elastic modulus is localized in the layered interlayer portion stably forms a layer thickness with high toughness regardless of changes in curing conditions, and has excellent impact resistance and interlayer toughness. , And contributes to providing plate edge peel strength. For example, in a particularly preferred embodiment in which a polyamide resin having an appropriate elastic modulus is used as each of the constituent elements [C] ([C ′]) and [D] ([D ′]), high heat resistance and interlayer shear strength are obtained. While maintaining, interlayer toughness G _IC is 600 J / m ²
The above and surprising properties of non-fiber orientation such as EDS of 70 ksi or more are exhibited. Moreover, surprisingly, this excellent impact resistance property and interlayer toughness are stably exhibited regardless of changes in molding conditions.

The combination of the constituent element [C] ([C ']) and the constituent element [D] ([D']) can be selected according to various purposes, but the constituent element [C] ([C ']) Fine particles made of a resin having a Tg of 40 ° C. or higher and lower than 160 ° C., a [D] ([D ′]) having a Tg of 100 ° C. or higher as a raw material, and a Tg of [C] ([C ′]) D]
When it is lower than Tg of ([D ']), the toughness is remarkably improved, which is preferable. Furthermore, the material of [C] ([C ']) has Tg of 40 ° C or higher and 100 ° C or lower, and [D]
The material of ([D ']) is a resin with a Tg of 100 ° C or higher,
When the Tg of [C] ([C ′]) is lower than the Tg of [D] ([D ′]) and the Tg of [B ′], the effect of the present invention is more remarkable. Here, the component [C]
Alternatively, the Tg of the resin used as the material of [D] was measured by using a differential scanning calorimeter (DSC), and the temperature rising rate was 40 ° C./min. It means what was measured in.

When only the component [C '] having a relatively low Tg is used in the interlayer part, high impact resistance, interlayer toughness and plate edge peel strength are provided, but compression strength, especially compression at high temperature It tends to impair the strength and the interlaminar shear strength. On the other hand, when only the component [D ′] having a relatively high Tg is used in the interlayer portion, high compressive strength and interlayer shear strength,
Although high impact resistance is given in some cases, it tends to have a small effect of improving interlayer toughness and plate edge peel strength. Therefore, the ratio of the constituent element [C] ([C ']) and 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 interlayer toughness and plate edge peel strength, [C]
The range of ([C ′]): [D] ([D ′]) = 9: 1 to 3: 7 is preferable, and the range of 9: 1 to 4: 6 is more preferable. On the other hand, in a design that emphasizes compressive strength, especially compressive strength at high temperature and interlaminar shear strength, [C]
The range of ([C ′]): [D] ([D ′]) = 7: 3 to 2: 8 is preferable, and the range of 6: 4 to 3: 7 is more preferable.

The elastic modulus of the constituent element [D] ([D ']) is 1
It is preferably 40 kg / mm ² or more in order to maintain the interlaminar shear strength and compressive strength of the composite material, and more preferably 170 kg / mm ² or more.

The constituent elements [C '] and [D'] play a role of stably forming a resin layer having a thickness of 10 to 70 μm in the laminated interlayer portion.

Regarding the analysis of the constituent elements [C '] and [D'], it is highly localized that they exist in the laminated interlayer portion of the composite material, and high impact resistance, interlaminar toughness, and excellent strip edge peel strength. Is important to give. Particularly preferred is a component [C 'in an "interlayer region" sandwiched between the layers in a fiber reinforced resin in which a plurality of layers composed of the component [A] and the component [B] are laminated. ] And [D '] 90% of the total amount
The above is the case of localization.

In the present invention, the "interlayer region" is a region formed in a portion where the layer consisting of the constituent element [A] and the constituent element [B] and the upper and lower layers are in contact with each other, as shown in FIG. Assuming that the average thickness of each layer is t, 0.15 t each is inserted vertically in the thickness direction from the surface where the layers are in contact with each other 0.3
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 0.2t, 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.

If 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 interlaminar toughness of the fiber reinforced resin will be described. ,
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,
The cross section is enlarged 70 times or more and 200 mm x 200 m
Create more than m photos. The photographs are taken so that the plane direction of the layers is parallel to one side of the photographs.

Using this photograph of the cross section, the average layer thickness is first 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, a cross section of the same composite material is enlarged 400 times or more to produce a photograph of 200 mm × 200 mm or more. Using this photograph, pay attention to one layer, and draw a line at the center of the layer.

Then, 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 one layer are 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 element [C] and [D ′] portions existing in a predetermined region from the cross-sectional photograph and weighing them. .

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 constituent element [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 brought into close contact therewith, 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, the average thickness of the prepreg is first determined. 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 determination of the fine particles is performed 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.

Components [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 resin after molding, there is no problem even if it changes from the form before molding and particles are fused to each other to some extent and become continuous. 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
The range of 70 μm is preferable.

A method for producing a prepreg in which the constituent elements [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 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.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 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 tetraglycidyldiaminodiphenylmethane (manufactured by Sumitomo Chemical Co., Ltd., ELM434) ... 65 parts by weight 2 Bisphenol A type epoxy resin (Yukaka Shell Epoxy Co., Ltd., Epicoat 828) ... 15 parts by weight 3 Bisphenol F type epoxy resin (Dainippon Ink and Chemicals, Epicron 830) ...... 20 parts by weight 44,4'-diaminodiphenyl sulfone (Sumitomo Chemical Co., Ltd., SUMICURE S) ・ ・ ・ ・ ・ 42 parts by weight C Nylon 12 fine particles (Toray Co., SP- 500) 6 parts by weight D Amorphous transparent nylon (manufactured by Mitsubishi Kasei Co., Ltd., Grillamide TR-55) / Bisphenol A type Epo Semi-IPN fine particles in which the weight fraction of xy resin (Yukaka Shell Epoxy Co., Ltd., Epicocoat 828) / polyamide-based curing agent (Fuji Kasei Co., Ltd., Tomid # 296) is 93/5/2 (Average particle size 16 μm) 8 parts by weight

The Tg of the components [C] and [D] is DS
When measured by C, [C] is 55 ° C and [D] is 15
It was 7 ° C.

The weight fraction of resin in the prepreg was 34.9.
%Met. Resin amount per unit area is 102g /
m ² , and the carbon fiber amount per unit area was 190 g / m ² .

This prepreg was sandwiched between two smooth Teflon plates and gradually heated up to 150 ° C. over 2 weeks to be cured, and its cross section was observed and micrographs were 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 9
8%, and the fine particles were sufficiently 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.
It was carried out under a pressure of 6 kgf / cm ^{2 for} an hour.

The cross section of the molded product was polished and the cross section was observed with a microscope. The two kinds of fine particles existed separately from the matrix resin in the interlayer region.

The evaluation of the average thickness of the layer was performed by taking a photograph magnified 50 times, and taking an average of 5 points to obtain 191 μm.
Met. Next, the ratio of fine particles existing in the interlayer region was evaluated by using five cross-sectional photographs of an arbitrary portion magnified 400 times and found to be 98% (width of the interlayer region is 44.3 μm).
m) It was localized between layers.

This pseudo isotropic hardened plate was 150 mm in length and 1 in width.
Cut to 00 mm, centered at 1500 inch-pounds /
After giving an impact of an inch falling weight, the damage area was measured by an ultrasonic flaw detection imaging device M400B manufactured by Canon / Holonics Co., and found to be 0.9 inch ² . Then ASTM
As a result of a compression test according to D-695, 50 ksi
The residual compressive strength of

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 610 J / m ² (double cantilever beam method).

(± 25 / ± 25/90) 10 with a configuration of _s
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 first determined to be 64.1 ksi.

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 compressive interlaminar shear strength (CILS) was determined to be 11.3 ksi.

Using a cured plate formed by laminating 6 layers of prepregs in one direction, the cured plate was used for 82 hours after absorbing water in warm water (72 ° C.) for 2 weeks.
The compressive strength at ℃ was determined according to SACMA SRS1-88, it was 191 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 para-aminophenol (manufactured by Yuka Shell Epoxy Co., Epicoat YX-4) ) ・ ・ ・ 40 parts by weight 2 Bisphenol A type epoxy resin (Epicote 828 manufactured by Yuka Shell Epoxy Co., Ltd.) ・ ・ ・ 20 parts by weight 3 Bisphenol F type epoxy resin (Dainippon Ink and Manufactured by Epicron 830) .. 40 parts by weight 44,4'-diaminodiphenyl sulfone (Sumicure S manufactured by Sumitomo Chemical Co., Ltd.) .. 42 parts by weight 5 Polyethersulfone (Mitsui) Toatsu Co., Ltd., 5003P: 10 parts by weight C Nylon 6 fine particles (Toray Co., SP-1000): 7 parts by weight D Riamidoimido (Amoco Corp., Torlon 4000T) fine ..... 5 parts by weight of the average particle diameter 23μm obtained by freeze-grinding the

DS of the Tg of the constituent elements [C] and [D]
When measured by C, [C] is 65 ° C and [D] is 28
It was 5 ° C.

The weight fraction of resin in the prepreg was 36.4.
%Met. Resin amount per unit area is 110g /
m ² , and the amount of carbon fiber per unit area was 192 g / m ² .

This prepreg was sandwiched between two smooth Teflon plates and gradually heated up to 150 ° C. for 2 weeks to be cured, and its cross section was observed and micrographs were 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 9
6%, and the fine particles were sufficiently 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.
It was carried out under a pressure of 6 kgf / cm ^{2 for} an hour.

The cross section of the molded product was polished and the cross section was observed with a microscope. The two kinds of fine particles existed separately from the matrix resin in the interlayer region.

The average thickness of the layer was evaluated by taking a 50 times magnified photograph, and the average of the five points was calculated to be 189 μm.
Met. Next, the ratio of the fine particles present in the interlayer region was evaluated by using five cross-sectional photographs of an arbitrary portion magnified 400 times and found to be 97% (the width of the interlayer region was 50.3 μm.
m) It was localized between layers.

This pseudo isotropic cured 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 1.1 inch ² . Then ASTM
As a result of a compression test according to D-695, 46 ksi
The residual compressive strength of

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 540 J / m ² (double cantilever beam method).

(± 25 / ± 25/90) 10 with a configuration of _s
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 first determined to be 61.7 ksi.

Using a cured plate obtained by laminating 24 layers of prepregs in one direction and molding, the compressive interlaminar shear strength (CILS) was 12.8 ksi.

Using a cured plate obtained by laminating 6 layers of prepregs in one direction and molding, 82 after water absorption in warm water (72 ° C.) for 2 weeks
The compressive strength at ℃ was 182 ksi.

Example 3 Part A: Synthesis of Reactive Polyimide Oligomer In a 3000 ml separable flask equipped with a nitrogen inlet, a thermometer, a stirrer and a dehydration trap, 392 g (0.91 mol) under nitrogen substitution. ) Screw [4-
(3-Aminophenoxy) phenyl] sulfone (BAP
SM), 39 g (0.11 mol) of 9,9'-bis (4-aminophenyl) fluorene (FDA), 147.
g (0.11 mol) NH ₂ equivalent of 650 amino-terminated dimethyl siloxane (commercially available BY-1 Silicone Company BY-1
6-853) was dissolved in 2000 ml of N-methyl-2-pyrrolidone (NMP) with stirring. There, 300 g (1.02 m) of solid biphenyltetracarboxylic dianhydride
ol) was added little by little, and after stirring at room temperature for 3 hours, 12
The temperature was raised to 0 ° C. and the mixture was 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, double the volume of N 2
Diluted with MP and slowly poured into 201 acetone to precipitate the amine end with a 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 5500 in terms of polyethylene glycol (PEG).
Met. Further, the glass transition point is a differential thermal analyzer (DSC).
According to 223 ° C. Further, the introduction of the siloxane skeleton and the presence of an amino terminal could be confirmed from the NMR spectrum and IR spectrum.

Part B: Resin Preparation of Component B and Resin Material
Sex measuring 25 parts of a siloxane polyimide oligomer of the part A in a beaker and phenol novolak type epoxy resin (Yuka Shell Epoxy Co., Ltd., Epikote 154) 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. Then, 34 parts of 4,4′diaminodiphenyl sulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) was added, and mixed and dissolved at 140 ° C. for 10 minutes.

A vacuum pump was connected to the container to perform degassing in a vacuum, 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 420 J / m ² , and the flexural modulus was 340 kg / mm ² .

When the polished surface of the cured resin was dyed with osmic acid and the backscattered electron image was observed with a scanning electron microscope, basically, a microphase-separated structure in which two phases together form a continuous phase was observed. 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
Measurement of physical properties 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 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 Machinery Co., Ltd. ), Epiclon 830) 30 parts by weight 4 4,4'-diaminodiphenylsulfone (Sumiture S, Sumitomo Chemical Co., Ltd.) 34 parts by weight 5 Siloxane polyimide described in part A Oligomer 25 parts by weight C Nylon 12 fine particles (SP-500 manufactured by Toray Industries, Inc.) 6 parts by weight D Amorphous transparent Niro (Di Mi nuts Novell Inc. TROGAMID® -T) particles ----- 7 parts by weight of the average particle diameter 22μm obtained by freeze-grinding the

The Tg of the constituent elements [C] and [D] is DS
When measured by C, [C] is 55 ° C and [D] is 16
It was 0 ° C.

The weight fraction of resin in the prepreg was 37.0.
%Met. Resin amount per unit area is 112 g /
m ² and the amount of carbon fiber per unit area were 191 g / m ² .

This prepreg was sandwiched between two smooth Teflon plates and gradually heated up to 150 ° C. for 2 weeks to be cured, and its cross section was observed and micrographs were 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 1
It was 100%, and the fine particles were sufficiently 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 two kinds of fine particles existed separately from the matrix resin in the interlayer region.

The evaluation of the average thickness of the layer was carried out by taking a photograph magnified 50 times, and the average of 5 points was taken to be 190 μm
Met. Next, the ratio of the fine particles present 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 30.4 mm).
μm) was localized between layers.

This pseudo isotropic cured 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 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, 55 ksi
The residual compressive strength of

Table 1 shows the results of the same post-impact compression test performed on the cured plate under different molding conditions. The physical properties were stable regardless of the molding conditions.

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 690 J / m ² (double cantilever beam method).

(± 25 / ± 25/90) 10 in the configuration of _s
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 77.4 ksi.

Using a cured plate obtained by laminating 24 layers of prepreg in one direction and molding, the compression interlaminar shear strength (CILS) was determined to be 11.0 ksi.

A cured plate obtained by laminating 6 layers of prepregs in one direction and molding was used. 82 after water absorption in warm water (72 ° C.) for 2 weeks
The compressive strength at ℃ was 185 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.

From the prepreg surface to the prepreg thickness of 30
When the amount of fine particles present in the range up to the% depth 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 observed by a microscope. As a result, the two types of fine particles existed separately from the matrix resin in the interlayer region. The average thickness of the layer was 190 μm. The ratio of fine particles existing in the interlayer region was 99%, which was localized between the layers.

After applying a drop impact of 1500 inch-pounds / inch to the center of this pseudo isotropic cured plate, the damage 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 the 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.

Using a cured plate obtained by laminating 6 layers of prepregs in one direction and molding, the compressive strength at 82 ° C. after absorbing water in warm water (72 ° C.) for 2 weeks was 141 ksi. It was significantly inferior in comparison.

[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.

From the prepreg surface to the prepreg thickness of 30
When the amount of fine particles existing in the range up to the% depth was evaluated, the value was 97%, 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 an optical microscope. As a result, the two kinds of fine particles existed 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 95%, which was localized between the layers.

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 1.1 inch ² . Then, as a result of a compression test, a residual compressive strength of 45 ksi was shown.

[0147] The compression interlaminar shear strength (CILS) of the cured plate obtained by laminating 24 layers in one direction and molding was 11.3.
It was ksi and was equivalent to the example.

However, the peeling mode toughness G _{IC of} the prepreg having 20 layers laminated in one direction was 250 J /
m ² (double cantilever beam method), which was significantly inferior to the examples.

Further, the EDS of a cured plate obtained by laminating 10 layers with a constitution of (± 25 / ± 25/90) _s was 43.5 ksi, which was significantly inferior to the examples. .

[Effects of the Invention] The prepreg according to the present invention has high heat resistance and excellent impact resistance when heat-molded into a composite material while securing tackiness and drapeability as the prepreg. , Has interlayer toughness. 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 resin whose high physical properties are stably expressed despite changes in molding conditions such as temperature rising rate, curing temperature, and pressure.

[0151]

[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 (24)

[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 made of resin [B]: Resin having a higher glass transition temperature (Tg) than [C] as a material Fine particles 2. 90% or more of the constituent [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,
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 a resin selected from the group consisting of: 4. The constituent [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 claim 1 or 2, wherein 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 component [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, as a material. The listed prepreg. 7. The constituent elements [C] and [D] have physical properties in the following ranges:
The prepreg described in the item. [C]: Fine particles made of a resin having a Tg of 40 ° C or higher and 160 ° C or lower [D]: Fine particles made of a resin having a Tg of 100 ° C or higher 8. The thermosetting resin in component [B] comprises at least one thermosetting resin from the group consisting of epoxy resins, cyanate resins and bismaleimide resins. The prepreg according to claim 1. 9. The component [B] is a thermosetting resin composition in which a thermoplastic resin selected from polyethersulfone, polysulfone, polyimide, polyetherimide and polyimide having a phenyltrimethylindane structure is mixed or dissolved. Claims 1 to 1 characterized in 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 siloxane 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 any one of claims 1 to 11, wherein the constituent element [A] is carbon (graphite) fiber. 13. The following components [A], [B '],
It consists of [C '] and [D'], and the component [C '],
A fiber reinforced resin characterized in that [D ′] is localized in the laminated interlayer portion. [A]: Reinforcing fiber consisting of long fibers [B ']: Cured thermosetting resin [C']: Fine particles made of resin [D ']: Made of resin having higher Tg than [C'] Fine particles 14. Component [C ′] and [D ′] 9
The fiber reinforced resin according to claim 13, wherein 0% or more is localized in the laminated interlayer portion. 15. The constituent [C ′] is polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polysulfone, poly The fiber-reinforced resin according to claim 13 or 14, which is made of a resin selected from the group consisting of ether sulfone, polyether ketone, polyether ether ketone, polyaramid, polyether nitrile and polybenzimidazole. 16. The component [D ′] is polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having a phenyltrimethylindane structure, polysulfone, poly The resin selected from the group consisting of ether sulfone, polyether ketone, polyether ether ketone, polyaramid, polyether nitrile and polybenzimidazole is used as a raw material. Fiber reinforced resin. 17. The fiber-reinforced resin 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-ized thermoplastic resin as a raw material.
The fiber-reinforced resin described. 19. The component [D ′] 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. 14. The fiber-reinforced resin according to 14. 20. The fiber reinforced resin according to claim 13, wherein the constituent elements [C ′] and [D ′] have the following physical properties. [C ']: Fine particle nonwoven fabric made of a resin having a Tg of 40 ° C or higher and 160 ° C or lower] [D']: Fine particles made of a resin having a Tg of 100 ° C or higher 21. 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 resin according to any one of items. 22. 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. 22. The fiber-reinforced plastic according to claim 13. 23. The fiber-reinforced plastic according to claim 13, wherein the constituent element [B ′] is a thermosetting resin cured product containing a polyimide having a silicon element. 24. The fiber-reinforced resin according to claim 13, wherein the constituent element [A] is carbon (graphite) fiber.