JPH0641332A - Prepreg and composite material - Google Patents

Abstract

PURPOSE:To provide a prepreg containing a reinforcing fiber, a matrix resin and more than a specific amount of a thermoplastic resin soluble in the matrix resin in a state localized within a prescribed depth from the surface of the prepreg, having excellent tackiness, drapeability and impact resistance and useful for composite material, etc. CONSTITUTION:The prepreg is composed of (A) a reinforcing fiber filament such as carbon fiber, (B) a matrix resin such as a mixture of a thermosetting resin (e.g. epoxy resin) and a thermoplastic resin (e.g. polyimide resin) and (C) preferably 1-50 pts.wt. (based on the component B) of fine particles of a thermoplastic resin soluble in the component B and having particle diameter of 150mum or smaller, wherein 90% or more of the component C is localized in the range from the surface to the depth corresponding to 30% of the thickness of the prepreg at one or both sides of the prepreg.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to prepregs and composite materials. More specifically, the present invention relates to a prepreg and a composite material used as a advanced composite material for a structure required to have high strength, elastic modulus, and specific strength and specific elastic modulus obtained by dividing these by specific gravity.

[0002]

2. Description of the Related Art A fiber-reinforced composite material is a heterogeneous material containing reinforcing fibers and a matrix resin as essential components,
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 falling weight impact is governed by the delamination strength, so that even if the strength of the reinforcing fiber is improved, it does not lead to a drastic improvement. Therefore, in addition to improving the toughness of the matrix resin, various methods have been proposed for the purpose of improving the physical properties other than the fiber axis direction.

US Pat. No. 3,472,730 (1
969), the peeling force against the interlayer is improved by disposing an independent outer layer film (separate exterior film) made of a thermosetting resin modified with an elastomeric substance on one or both sides of the fiber reinforced sheet. It is disclosed that this is done.

Japanese Unexamined Patent Publication (Kokai) No. 51-58484 discloses that the presence of a polyether sulfone film on the surface of a fiber reinforced epoxy resin prepreg improves moldability and bending strength.

JP-A-54-3879 and JP-A-56.
-115216 and JP-A-60-44334 disclose that short fiber chips, chopped strands and milled fibers are arranged between layers of a fiber reinforced sheet to improve interlayer strength.

JP-A-60-63229 discloses that an epoxy resin film modified with an elastomer is placed between layers of a fiber reinforced prepreg to improve the interlayer strength.

In US Pat. No. 4,539,253 (JP-A-60-231738), an elastomer is used for a non-woven fabric, a woven fabric, a mat or a carrier, which is based on a lightweight fiber between layers of a fiber reinforced prepreg. It is disclosed that a film impregnated with a modified epoxy resin is provided to improve the interlaminar strength.

US Pat. No. 4,604,319 (JP-A-60-231738) discloses that a thermoplastic resin film is placed between layers of a fiber reinforced prepreg to improve interlayer strength. ing.

However, these methods are not only insufficient in their effects, but also have their respective drawbacks.
When an independent outer layer film containing an elastomer-modified thermosetting resin is used, the content of elastomer increases,
When the heat resistance is lowered and the content of the elastomer is low, the effect of improving the interlaminar strength is very small.

When a thermoplastic resin film is used, both heat resistance and interlayer strength improving effect can be achieved by using a thermoplastic resin film having good heat resistance. The advantages of tackiness (adhesiveness) and drapeability are lost. Further, the general defect of the thermoplastic resin that the solvent resistance is not good is reflected in the composite material.

The use of short fiber chops, chopped strands, and milled fibers causes the interlayer to become thicker, resulting in a decrease in strength of the composite as a whole.

On the other hand, as an attempt to overcome these drawbacks, a method of dispersing thermoplastic resin particles between layers of a fiber reinforced prepreg has been proposed.

For example, US Pat. No. 5,028,478 (JP-A-63-162732, JP-A-63-63732)
170427, JP-A-63-170428, JP-A-1-104624, and JP-A-1-104625), a thermoplastic resin such as nylon is used to sacrifice the tack and drape of the prepreg. Without the need to provide a high toughness composite material with good heat resistance.

Japanese Unexamined Patent Publication (Kokai) No. 3-26750 provides a technique of providing a high toughness composite material by combining a matrix resin having improved toughness and thermosetting resin particles. In this case, since the matrix resin has high toughness, it is possible to achieve high toughness by adding a small amount of resin fine particles.

However, these US Pat. No. 5,028,4
In the method of Japanese Patent Laid-Open No. 78 and Japanese Patent Laid-Open No. 3-26750,
When the composite material is kept in a fatigue environment for a long period of time, if the adhesiveness between the particles used and the matrix resin is not good, interfacial peeling may occur and the initial toughness value may be greatly reduced.

Japanese Patent Publication No. 2-311538, Japanese Patent Publication No. 3
-197559, European Patent Publication 377194 and European Patent Publication 392348 use thermoplastic resin particles such as polyimide and polyether sulfone, and are similar to the above-mentioned US Pat. No. 5,028,478. In addition, a technology for providing a high toughness composite material having good heat resistance without sacrificing the tackiness and drape property of the prepreg is provided. The particles used at this time are dissolved in the matrix resin at the time of curing the prepreg to form a resin layer separate from the fiber layer, which improves the toughness of the composite material. However, Japanese Examined Fairness 2-31
In the example of Japanese Patent No. 1538, the residual compressive strength after impact (hereinafter, CAI), which is an index of the impact resistance of the composite material, is 3
The improvement is limited to about 8 ksi, and the improvement effect is slight. Similarly, in the example of Japanese Patent Publication No. 3-197559, the effect of improving the CAI is not so large, but in this case, since the particles are uniformly blended in the resin, they are independent in the cured product. It is presumed that this is because it is difficult to form the resin layer. Also, European Published Patent No. 3
77194 and European Patent No. 392348 reported that CAI was improved by about 13 ksi, but in this case, the CAI was 2% compared to the matrix resin.
Since a large amount of particles of 0% is used, it is considered that tackiness and drapability are largely sacrificed.

[0017]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a composite material which overcomes the above-mentioned drawbacks and further has significantly improved physical properties other than in the fiber axis direction.

[0018]

The prepreg of the present invention has the following constitution in order to solve the above problems. That is, in the prepreg consisting of the following constituent elements [A], [B], and [C], 90% or more of [C] has a depth range of 30% of the thickness of the prepreg on one side or both sides of the prepreg. It is a prepreg characterized by being localized inside.

[A]: Reinforcing fiber consisting of long fibers [B]: Matrix resin [C]: Fine particles consisting of thermoplastic resin soluble in component [B] The composite material of the present invention solves the above problems. Therefore, it has one of the following configurations. That is, the following constituent elements [A], [B], and [L] are essential, and [L] is localized between the laminated layers, or [A]: long fibers Reinforcing fiber [B]: Matrix resin [L]: High toughness resin layer having a phase-separated structure Consist of the above-mentioned constituent elements [A], [B] and [C],
90% or more of [C] is a composite material characterized by being laminated on one or both sides of the prepreg with a prepreg localized within a depth range of 30% of the thickness of the prepreg. .

The present invention will be described in detail below for each component. (Explanation of Constituent Element [A]) The constituent element [A] of the prepreg of the present invention is a reinforcing fiber made of long fibers. The reinforcing fiber used in the present invention is generally a fiber having good heat resistance and tensile strength, which is used as a high performance reinforcing fiber. Examples of the reinforcing fiber include carbon fiber, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, and boron fiber. Among these, carbon fiber and graphite fiber, 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 invention. It is possible to use all kinds of carbon fibers and graphite fibers depending on the application, but the tensile strength is 450 Kgf / mm ² , and the tensile elongation is 1.
High strength and high elongation carbon fiber of 6% or more is most suitable. Further, in the present invention, long fiber-shaped reinforcing fibers are used, 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. The shape and arrangement of the reinforcing fiber are not 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. Also, in particular, the specific strength,
For applications requiring a high specific elastic modulus, an array in which reinforcing fibers are aligned in a single direction is most suitable, but a cloth (fabric) array that is easy to handle is also suitable for the present invention. ing. (Description of Component [B]) Examples of the matrix resin used in the present invention include a thermosetting resin and a resin obtained by mixing a thermosetting resin and a thermoplastic resin.

The thermosetting resin used in the present invention is cured by heat or energy from the outside such as light or electron beam,
The resin is not particularly limited as long as it is a resin that at least partially forms a three-dimensional cured product. As a preferable thermosetting resin,
An epoxy resin can be used, and it is generally used in combination with a curing agent or a curing catalyst.

The epoxy resin suitable for the present invention is particularly preferably an epoxy resin containing an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor. Further, these epoxy resins may be used alone,
You may mix and use it suitably.

The epoxy resin is preferably used in combination with an epoxy resin curing agent. The epoxy curing agent is
Any compound having an active group capable of reacting with an epoxy group can be used. A compound having an amino group, an acid anhydride group or an azido group is preferable.

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 the present invention, a polymaleimide resin, a resin having a cyanate ester terminal, and an addition-curable polyimide resin having a reactive terminal are preferably used as the matrix resin. These may be appropriately mixed with an epoxy resin or another resin. Also, a reactive diluent may be used, or a modifier such as a thermoplastic resin or an elastomer may be mixed and used.

The polymaleimide resin is a compound containing an average of two or more maleimide groups at the terminal and is produced by a known method of reacting a corresponding diamine with an unsaturated dicarboxylic acid anhydride. Examples of preferable polymaleimides used in the present invention are shown below.

4,4'-bismaleimide diphenylmethane, polymaleimide aniline resin, 4,4'-bismaleimide diphenyl ether, 3,3'-bismaleimide diphenyl sulfone, 1,3-bismaleimide benzene, 2,4-bisimide Toluene, 1,6-bismaleimidohexane and 2,2,4-trimethyl-1,6-bismaleimidohexane. These may be used alone or in combination of two or more.

These polymaleimide compounds are generally used with reactive diluents. Such a reactive diluent is capable of chemically reacting with the maleimide moiety, and
It is a compound that is liquid at room temperature, and is preferably alkenylphenol and / or alkenylphenol ether. These compounds have already been described in JP-B-55-39242 and U.S. Pat. No. 1,048,615 as suitable reactive diluents for polymaleimides.
Examples of alkenylphenols that can be used in the method of the present invention include the following substances.

O, o'-diallyl-bisphenol A,
4,4'-hydroxy-3,3'-allyl -, bis - (4-hydroxy-3-allyl - ... unnecessary ...?
Phenyl) - methane, 2,2-bis - (4-hydroxy-3,5-diallyl - ... unnecessary ... phenyl) -?, Etc. propane and eugenol.

"Matrimid 5292" (registered trademark) is commercially available from Ciba-Geigy Co., Ltd. as an example of a resin composed of the combination of the polymaleimide and the reactive diluent shown above, and is suitable for the present invention.

The resin having a cyanate ester terminal is preferably a cyanate ester compound of a polyhydric phenol represented by bisphenol A. The cyanate ester resin can be made into a resin suitable for prepreg particularly by combining with the above-mentioned polymaleimide resin, and BT resin manufactured by Mitsubishi Gas Chemical Co., Inc. is commercially available and suitable for the present invention. .

The addition-curable polyimide resin having a reactive terminal is obtained by reacting a tetracarboxylic acid dianhydride with a diamino compound, sealing the terminal with a double bond-containing acid anhydride, and then imide ring-closing. Can be synthesized by Preferred examples of the tetracarboxylic dianhydride are pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′,
4,4'-biphenyltetracarboxylic dianhydride, 3,
Aromatic tetracarboxylic dianhydrides such as 3 ′, 4,4′-diphenyl ether tetracarboxylic dianhydride, more preferably 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride Aromatic tetracarboxylic dianhydrides such as 3 ', 4,4'-diphenyl ether tetracarboxylic dianhydride can be mentioned.

Preferred examples of diamino compounds include diaminodiphenylmethane, metaphenylenediamine, paraphenylenediamine, diaminodiphenyl ether,
Diaminodiphenylsulfone, diaminodiphenyl sulfide, diaminodiphenylethane, diaminodiphenylpropane, diaminodiphenyl ketone, diaminodiphenylhexafluoropropane, bis (aminophenoxy) benzene, bis (aminophenoxy) diphenylsulfone, bis (aminophenoxy) diphenylpropane, bis (Aminophenoxy) diphenylhexafluoropropane, fluorenediamine, dimethyl substitution product of diaminodiphenylmethane, tetramethyl substitution product of diaminodiphenylmethane, diethyl substitution product of diaminodiphenylmethane, tetraethyl substitution product of diaminodiphenylmethane, dimethyldiethyl substitution product of diaminodiphenylmethane, etc. Aromatic diamino compounds, more preferably bis (aminophenyl) Phenoxy) benzene, bis (aminophenoxy) diphenyl sulfone, bis (aminophenoxy) diphenyl propane, bis (aminophenoxy) diphenyl hexafluoropropane, fluorene diamine, dimethyl substitution product of diaminodiphenylmethane,
Examples thereof include aromatic diamino compounds such as tetramethyl-substituted diaminodiphenylmethane, diethyl-substituted diaminodiphenylmethane, tetraethyl-substituted diaminodiphenylmethane, and dimethyldiethyl-substituted diaminodiphenylmethane.

Preferred examples of the double bond-containing acid anhydride are nadic acid anhydride derivatives such as nadic acid anhydride, a methyl substitution product of nadic acid anhydride, and a chlorine substitution product of nadic acid anhydride.

As the matrix resin used in the present invention,
It is also preferable to use a thermoplastic resin mixed with the above thermosetting resin. The thermoplastic resin suitable for the present invention, carbon-carbon bond, amide bond, imide bond, ester bond, ether bond, siloxane bond, carbonate bond, urethane bond, urea bond, thioether bond, sulfone bond, imidazole bond in the main chain, A thermoplastic resin having a bond selected from carbonyl bonds can be selected. Considering heat resistance and impact resistance, a thermoplastic resin having an imide bond is particularly preferable.

As the thermoplastic resin, a commercially available polymer may be used, but the molecular weight thereof is lower than that of the commercially available polymer.
It is preferable to use so-called oligomers. The number average molecular weight of the oligomer is 1 in order to prevent the resin viscosity at the time of molding from becoming too high and impairing the fluidity of the resin.
From the viewpoint of preventing the thermoplastic resin from having a small effect of improving the toughness, the impact resistance of the composite material cannot be sufficiently increased. The number average molecular weight of the oligomer is preferably 3000 or more. Further, it is more preferable that the oligomer has a functional group capable of reacting with the thermosetting resin at the terminal or in the molecular chain.

The mixture of thermosetting resin and thermoplastic resin is
Better results are obtained when they are used alone. This is because while thermosetting resins generally have the disadvantage of being brittle, low-pressure molding by autoclave is possible, while thermoplastic resins generally have the advantage of being tough, while low-pressure molding by autoclaving. This is because they have the contradictory property of being difficult to mold, and by using them in a mixture, the physical properties and moldability can be balanced. (Description of Constituents [C] and [L]) <Distribution of Constituent [C]> Regarding the distribution of the constituent [C], the surface layer of the prepreg, that is, the prepreg sheet when molded into a composite material The uneven distribution between the prepreg sheet and the prepreg sheet is important for providing a composite material having excellent impact resistance.

When the constituent element [C] is uniformly distributed in the constituent element [B], only a modifying effect corresponding to the content ratio of the constituent element [C] to the matrix resin is expected. . However, when unevenly distributed between the layers of the composite material, the effect based on mere additivity was far exceeded, and a particularly unexpected and remarkable effect was found with respect to improvement of impact resistance. Of. To satisfy this condition, 90% or more of the fine particles dispersed on the surface portion must be localized within a depth range of 30% of the thickness of the prepreg. If fine particles enter deep inside the prepreg outside this condition, the impact resistance of the composite material becomes poor.

When 90% or more of the fine particles are localized within the depth range of 10% of the thickness of the prepreg from the surface of the prepreg, a more remarkable impact resistance improving effect appears, which is more preferable. .

The prepreg according to the present invention is preferably one in which fine particles are unevenly distributed on both surfaces of the prepreg from the viewpoint of being able to freely laminate regardless of the front and back of the prepreg. However, even in a prepreg in which fine particles have a similar distribution on only one surface of the prepreg, the same effect can be obtained if the prepreg is laminated with care so that the fine particles are always between the prepregs.

<Evaluation Method of Distribution of Component [C]> The distribution state of fine particles in the prepreg is evaluated as follows.

First, the prepreg is sandwiched between two smooth support plates and brought into close contact with each other, and the temperature is gradually raised and cured over a long period of time. At this time, it is important to gel at a temperature as low as possible. If the temperature is raised before gelation, the matrix resin in the prepreg will flow and the fine particles will move, or the fine particles will dissolve in the matrix resin, making it impossible to accurately evaluate the distribution state in the prepreg. Will end up.

After the gelling, the prepreg is hardened by gradually increasing the temperature over a further period of time. Using this cured prepreg, expand its cross section by 200 times or more,
Take a picture of 200mm x 200mm or more.

Using this photograph of the cross section, the average thickness of the prepreg is first determined. The average thickness of the layer is measured at at least 5 places arbitrarily selected on the photograph, and the average thereof 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,
The amount of fine particles present within 30% of the thickness of the prepreg from the surface of the prepreg is calculated by quantifying this and the area of the fine particles present over the entire width of the prepreg and taking the ratio. The area of the fine particles is quantitatively determined by cutting out all the fine particle portions existing in a predetermined region from the cross-sectional photograph and measuring the weight. In order to eliminate the influence of the variation in the partial distribution of the fine particles, this evaluation was performed over the entire width of the obtained photograph, and the same evaluation was performed for five or more photographs arbitrarily selected. You need to take the average.

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

<Size of Component [C]> The size of the fine particles is expressed by the particle size. The size of component [C] is
When it becomes a composite material, it should not be so large as to significantly disturb the arrangement of the reinforcing fibers. If the particle size exceeds 150μ,
Since the arrangement of the reinforcing fibers is disturbed or the layers of the composite material obtained by laminating are made thicker than necessary, there are drawbacks that the physical properties of the composite material are deteriorated. More preferably, 50μ
The following particles may be used.

<Amount of Constituent [C] Added> The amount of the constituent [C] has an effect of improving impact resistance by addition of fine particles, while facilitating the mixing with the constituent [B] and making the prepreg of the prepreg. From the viewpoint of preventing the tack and drape properties from being significantly reduced, 1 to 50% by weight of the constituent element [B]
It is preferably in the range of.

In particular, for the purpose of increasing the toughness between the layers of the composite material with a high toughness resin layer having a flexible property with a high breaking elongation, while the rigidity of the matrix resin is utilized for expressing the compressive strength of the composite material. If used, 1% by weight to 15
A weight% range is preferred.

<Material of Component [C] and Phase Separation Form of [L]> The component [C] may be any resin as long as it is soluble in [B]. Furthermore, it is more preferable if the solubility is lowered in the curing process and a resin layer having a phase separation structure is formed between the laminated layers. In order to form such a resin layer, in addition to a method of alternately laminating a resin film having a phase separation structure and a prepreg, when using a prepreg in which thermoplastic resin particles are dispersed in the vicinity of the surface, It is considered to be a more preferable method because the tack drape property can be greatly improved.

The thermoplastic fine particles used in the present invention are preferably phase-separated after being once dissolved in the constituent element [B] in the process of heating and curing the laminated prepreg. Preferred materials for such thermoplastic resin fine particles are, for example,
In the main chain, carbon-carbon bond, amide bond, imide bond, siloxane bond, ester bond, ether bond, siloxane bond, carbonate bond, urethane bond, urea bond, thioether bond, sulfone bond, imidazole bond,
A thermoplastic resin having a bond selected from carbonyl bonds, specifically, polyamide, polycarbonate,
Polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyetherimide, polysiloxane,
Examples thereof include polysulfone, polyether sulfone, polyether ether ketone, polyaramid, and polybenzimidazole. Among them, the polyetherimide compound having a structure represented by the following formula [I] has flexibility and toughness due to the presence of an ether bond in the molecule without significantly impairing the heat resistance characteristic of polyimide. It is particularly preferable from the viewpoint of being excellent.

[0051]

[Chemical 2] Further, from the viewpoint of further improving the toughness and further improving the impact resistance of the composite material, the number average molecular weight of this polyetherimide compound is 5,000 or more, and further 10,000.
The above is preferable.

Such polyetherimide compound can be synthesized from the corresponding aromatic diamino compound and 3,3 ', 4,4'-diphenyl ether tetracarboxylic dianhydride. Examples of aromatic diamino compounds include:
Examples thereof include bis (aminophenoxy) diphenylpropane, bis (aminophenoxy) diphenylhexafluoropropane, and bis (aminophenoxy) diphenylsulfone. It is preferable that the ether bond has a meta-coordination or ortho-coordination, rather than a para-coordination mode, since the flexibility of the molecule is high and the flexibility, toughness and solubility are high.

By the way, as a phase separation form of the constituent element [L] in the composite material obtained from the prepreg, a structure in which a component rich in thermosetting resin is dispersed in a component rich in thermoplastic resin, conversely, A structure in which a component rich in thermoplastic resin is dispersed in a component rich in thermosetting resin, and a structure in which both resin components rich in thermosetting resin and component rich in thermoplastic resin form a continuous phase, etc. Can be considered. Among these phase-separated structures, the constituent element [L] has at least higher toughness in order to absorb the energy more effectively and consequently realize the composite material having good impact resistance. Advantageously, the thermoplastic resin-rich resin phase forms a continuous phase, preferably three-dimensionally. It is also preferable to have a finer dispersed phase of another phase inside each continuous phase. In order to realize such a dispersion structure, for example, as described in JP-B-2-305860, the thermoplastic resin particles include a component easily dissolved in the constituent element [B] and a constituent element. It is preferable that [B] has a structure having a component which is not easily dissolved.

As the component which is easily dissolved in the constituent element [B], a carbon-carbon bond, an amide bond, an imide bond, an ester bond, an ether bond, a carbonate bond,
A thermoplastic resin having a bond selected from a urethane bond, a urea bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond can be selected, but in consideration of heat resistance and impact resistance, a thermosetting resin having an imide bond is used. Plastic resins are particularly preferred. On the other hand, as a component which is not easily dissolved in the constituent element [B], a thermoplastic resin having a siloxane bond can be mentioned. Therefore, as the material of the constituent element [C], a thermoplastic resin having both an imide bond soluble in [B] and a non-soluble siloxane bond is more preferable.

Now, the two phases in the phase-separated structure formed in the component [L] have different elastic moduli.
When stress is applied, stress concentration occurs at the phase interface portion, and fracture easily propagates along this phase structure. At this time, the fact that the constituent elements are connected by a chemical bond brings about the effect of not causing phase interface separation. Therefore, in order to increase the adhesiveness of the phase interface in the phase-separated structure formed in the constituent [L], the constituent [B ] It is preferable to introduce a functional group capable of reacting with. Examples of such a functional group include an amino group, a hydroxyl group and a carboxyl group.

As the thermoplastic resin, a polymer may be used, but it is more preferable to use a so-called oligomer having a lower molecular weight than the polymer. The oligomer here is a compound having a number average molecular weight of 10,000 or less. When a polymer having a molecular weight of more than 10,000 is used, the resin viscosity at the time of molding becomes too large and the fluidity of the resin is impaired, which is not preferable in terms of moldability. On the other hand, if the molecular weight of the oligomer is too low, the fluidity of the interlayer portion becomes too large, and the interlayer resin layer having an appropriate thickness cannot be formed in the composite material, or even if the interlayer resin layer is obtained. However, since the toughness of this portion becomes low, the impact resistance of the composite material cannot be sufficiently enhanced. The preferred molecular weight range of the oligomer is 30
It is 00-7000.

<Amount of Thermoplastic Resin in Component [L]>
The thermoplastic resin-rich phase present in component [L] is
From the viewpoint that the phase rich in thermoplastic resin can be easily made into a continuous phase, it is preferably 20% by volume or more, further preferably 30% by volume or more of this resin layer.

<Thickness of Component [L]> Such a thickness of the component [L] has a sufficient effect of impact resistance, while the fiber content in the composite material becomes too small, and From the viewpoint of preventing the strength and elastic modulus from significantly decreasing, the thickness is preferably in the range of 1 to 50% of the thickness of each layer. Especially when the composite resin is used for the purpose of increasing the toughness between the layers of the composite material by using the high toughness resin layer having a high breaking elongation and flexible characteristics while making use of the rigidity of the matrix resin for expressing the compressive strength of the composite material. Is 5 to 20%
Ranges are preferred.

[0059]

The present invention will be described in more detail with reference to the following examples. Reference Example 1 (Synthesis of Siloxaneimide Fine Particles) In a 500 ml separable flask equipped with a nitrogen inlet, a thermometer, a stirrer and a dehydration trap, under nitrogen substitution, 23.
49 g (0.0768 mol) of Wakayama Seika Co., Ltd. 2,2-
Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 27.71 g (0.0768 mol)
Amino-terminated dimethylsiloxane (X22-161-AS manufactured by Shin-Etsu Chemical Co., Ltd.) having an amino group equivalent of 440 was added, and 150 ml of dimethylacetamide was further added to uniformly dissolve the solid content. After the entire system was sufficiently cooled with ice water, 19.64 g (0.0668 mol) of biphenyltetracarboxylic dianhydride manufactured by Mitsubishi Kasei Co., Ltd. was added under ice cooling while stirring. After the addition was completed, the mixture was stirred under ice cooling for 1 hour, and further stirred at room temperature for 1 hour.
Then, the system was heated to 100 ° C. and stirred for 1 hour to complete the reaction.

After the system was returned to room temperature, 20 ml of toluene and 10 ml of triethylamine were added, the system was heated again, and water produced by the reaction was removed from the system by azeotroping with toluene, After 2 hours, almost the theoretical amount of water was obtained.

After the reaction mixture was cooled to room temperature, it was poured into water, and the produced solid substance was collected by filtration. The solid was dried overnight to give 55 g of a pale yellow solid (yield 75
%). This is sieved through a 200 mesh screen to obtain 74μ
Fine particles having the following particle size were obtained. Example 1 A unidirectional prepreg having the following constitution was manufactured. The prepreg is manufactured by first preparing a prepreg consisting of the following reinforcing fibers and a matrix resin in which the weight fraction of the matrix resin is 32%, and then the imide siloxane resin fine particles synthesized in Reference Example 1 on one side of the prepreg. This was done by applying evenly.

<Reinforcing fiber>: Toray Industries, Inc. carbon fiber “Torayca” T800H-12K (registered trademark) <Matrix resin composition>: N, N-bismaleimidediaminodiphenylmethane (manufactured by Ciba-Geigy, 5292A) 215 parts by weight N , N-bismaleimide tolylenediamine (Mitsui Toatsu Co., Ltd., BMI-TDA) 113 parts by weight o, o-diallyl bisphenol A (Ciba Geigy 5292B) 246 parts by weight Thermoplastic polyimide (Ciba Geigy 5218) 64 parts by weight <fine particles>: Imidosiloxane resin fine particles obtained in Reference Example 113 113 parts by weight The weight fraction of the resin in the obtained prepreg was 36%. The amount of carbon fiber per unit area was 190 g / m ² .

The prepreg was sandwiched between two smooth Teflon plates, gradually heated to 150 ° C. over 7 days to be cured, and the cross section was observed. When the amount of fine particles present in the range from the prepreg surface to 30% of the thickness of the prepreg was evaluated, the value was 96%.

Next, this prepreg is simulated isotropically 24
Layered one by one, and molded by ordinary autoclave at 190 ℃
At a pressure of 6 kgf / cm ² for 4 hours. When the cross section was observed with an electron microscope after molding, it was found that a microphase-separated structure having an imidosiloxane portion as a continuous phase was formed.

These cross-section observations could be performed without dyeing the fine particles with a dyeing agent.

A pseudo isotropic hardened plate is 150 mm long and 100 mm wide.
After cutting, and applying a falling weight impact of 1500 inch-pounds / inch to the center, the damage area was measured by an ultrasonic flaw detector and found to be 1.1 square inches. Then
The compressive strength after impact was measured according to ASTM D-695 and was found to be 45 ksi.

Next, using the same prepreg, one direction 16
A ply laminated plate is molded into a composite material having a thickness of about 2 mm, cut into a length of 127 mm in the yarn direction and a width of 1.9 mm, and a tensile test is performed at a test length of 60 mm and a displacement speed of 2.5 mm / min in a direction perpendicular to the fiber direction. Was done. The tensile strength at this time is 9.
It was 0 kgf / mm ² . [Example 2] A unidirectional prepreg having the same structure as in Example 1 except that 34 parts by weight of the imidosiloxane resin fine particles synthesized in Reference Example 1 was used as the constituent element [C].

Twenty-four sheets of this prepreg were quasi-isotropically laminated, and molding was carried out by an ordinary autoclave at 190 ° C. for 4 hours under a pressure of 6 kgf / cm ² . When the cross section was observed with an electron microscope after molding, it was found that a microphase-separated structure having an imidosiloxane portion as a continuous phase was formed.

These cross-sections could be observed without dyeing the fine particles with a dyeing agent.

A pseudo isotropic hardening plate is 150 mm long and 100 mm wide.
After cutting, and applying a falling weight impact of 1500 inch-pounds / inch to the center, the damage area was measured by an ultrasonic flaw detector and found to be 2.0 square inches. Then
The compressive strength after impact was measured according to ASTM D-695 and was 38 ksi.

Next, using the same prepreg, one direction 16
A ply laminated plate is molded into a composite material having a thickness of about 2 mm, cut into a length of 127 mm in the yarn direction and a width of 1.9 mm, and a tensile test is performed at a test length of 60 mm and a displacement speed of 2.5 mm / min in a direction perpendicular to the fiber direction. Was done. The tensile strength at this time is 9.
It was ² kgf / mm ² . [Example 3] As component [C], 5218 (polyimide manufactured by Ciba-Geigy) was freeze-pulverized to obtain a particle size of 100.
A unidirectional prepreg having the same structure as in Example 1 except that fine particles of μ or less was used was manufactured.

This prepreg was sandwiched between two smooth Teflon plates, gradually heated to 150 ° C. over 7 days to be cured, and the cross section was observed. When the amount of fine particles present in the range from the surface of the prepreg to 30% of the thickness of the prepreg was evaluated, the value was 94%.

Next, 24 sheets of this prepreg were pseudo-isotropically laminated and molded by a normal autoclave at 190 ° C.
At a pressure of 6 kgf / cm ² for 4 hours. After molding, when observing the cross section with an electron microscope, it was found that a microphase-separated structure having a polyimide portion as a continuous phase was formed.

These cross-sections could be observed without dyeing the fine particles with a dyeing agent.

A pseudo isotropic hardening plate is 150 mm long and 100 mm wide.
After cutting, and applying a falling weight impact of 1500 inch-pounds / inch to the center, the damaged area was measured by an ultrasonic flaw detector to find that it was 3.5 square inches. Then
The compressive strength after impact was measured to be 35 ksi according to ASTM D-695.

Next, using the same prepreg, one direction 16
A ply laminated plate is molded into a composite material having a thickness of about 2 mm, cut into a length of 127 mm in the yarn direction and a width of 1.9 mm, and a tensile test is performed at a test length of 60 mm and a displacement speed of 2.5 mm / min in a direction perpendicular to the fiber direction. Was done. The tensile strength at this time is 9.0 kg
It was f / mm ² . Example 4 A unidirectional prepreg having the following constitution was manufactured. The prepreg is manufactured by first preparing a prepreg consisting of the following reinforcing fibers and a matrix resin in which the weight fraction of the matrix resin is 32%, and then the imide siloxane resin fine particles synthesized in Reference Example 1 on one side of the prepreg. This was done by applying evenly.

<Reinforcing fiber>: Toray Industries, Inc. carbon fiber “Torayca” T800-H-12K (registered trademark) <Matrix resin composition>: N, N-bismaleimidediaminodiphenylmethane (manufactured by Ciba-Geigy, 5292A) 215 parts by weight Parts N, N-Bismaleimide tolylenediamine (Mitsui Toatsu Co., Ltd., BMI-TDA) 113 parts by weight o, o-diallyl bisphenol A (Ciba Geigy, 5292B) 246 parts by weight <fine particles>: Reference Example 1 101 parts by weight of the imidosiloxane resin fine particles obtained in the above. The weight fraction of the resin in the obtained prepreg was 35%. 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. over 7 days to be cured, and the cross section was observed. When the amount of fine particles present in the range from the surface of the prepreg to 30% of the thickness of the prepreg was evaluated, the value was 95%.

Next, 24 sheets of this prepreg were pseudo-isotropically laminated and molded by a normal autoclave at 190 ° C.
At a pressure of 6 kgf / cm ² for 4 hours. When the cross section was observed with an electron microscope after molding, it was found that a microphase-separated structure having an imidosiloxane portion as a continuous phase was formed.

These cross-sections could be observed without dyeing the fine particles with a dyeing agent.

A pseudo isotropic hardening plate is 150 mm long and 100 mm wide.
After cutting, and applying a falling weight impact of 1500 inch-pounds / inch to the center, the damage area was measured by an ultrasonic flaw detector to find that it was 3.6 square inches. Then
The compressive strength after impact was measured to be 33 ksi according to ASTM D-695.

Next, using the same prepreg, one direction 16
A ply laminated plate is molded into a composite material having a thickness of about 2 mm, cut into a length of 127 mm in the yarn direction and a width of 1.9 mm, and a tensile test is performed at a test length of 60 mm and a displacement speed of 2.5 mm / min in a direction perpendicular to the fiber direction. Was done. The tensile strength at this time is 8.
It was 8 kgf / mm ² . [Comparative Example 1] As the constituent [C], Torlon (polyamideimide manufactured by Amoco) was freeze-pulverized to obtain an average particle diameter of 2
A unidirectional prepreg having the same structure as in Example 4 except that 5 μm fine particles were used was manufactured.

When the amount of fine particles present in the range from the surface of the prepreg to 30% of the thickness of the prepreg was evaluated, the value was 95%. Further, when the cross section of the composite material after molding was observed, it was confirmed that the used fine particles remained undissolved and were concentrated in the interlayer portion of the laminate.

After the falling weight impact of 1500 inch-pounds / inch was applied to the pseudo isotropic plate, the damage area was measured by an ultrasonic flaw detector and found to be 4.3 square inches. Next, when the compressive strength after impact was measured, it was 24 ksi.
Which was inferior to the examples. In addition, when the damaged portion is observed with an optical microscope, as shown in FIG. 2, it can be seen that the path of the crack propagating between the layers is linear, and no significant energy absorption is performed.

Further, when a tensile test was carried out perpendicularly to the fiber direction, the tensile strength was 8.4 kgf / mm ² , which was inferior to the examples. [Comparative Example 2] A unidirectional prepreg having the same configuration as in Example 1 was produced except that the constituent element [C] was not used.

After a falling weight impact of 1500 inch-pounds / inch was applied to the pseudo isotropic plate, the damage area was measured by an ultrasonic flaw detector and found to be 5.1 square inches. Next, when the compressive strength after impact was measured, it was 23 ksi.
Which was inferior to the examples.

Further, when a tensile test was carried out perpendicularly to the fiber direction, the tensile strength was 8.5 kgf / mm ² , which was inferior to the examples. (Reference Example 2) [Synthesis of polyetherimide fine particles] 500 ml equipped with a nitrogen inlet, a thermometer, a stirrer and a dehydration trap
In a separable flask of 5 volume under nitrogen substitution.
1.85 g (0.100 mol) of Wakayama Seika's 2,2
-Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane and 150 ml of dimethylacetamide were added to uniformly dissolve the solid content. After sufficiently cooling the whole system with ice water, 31.02 g (0.10
(0 mol) of diphenyl ether tetracarboxylic acid dianhydride manufactured by Daicel Chemical Industries, Ltd. was added under ice cooling while stirring. After the addition was completed, the mixture was stirred under ice cooling for 1 hour, and further stirred at room temperature for 1 hour. Then, the system was heated to 100 ° C. and stirred for 1 hour to complete the reaction.

After returning the system to room temperature, 20 ml of toluene and 10 ml of triethylamine were added, the system was heated again, and water produced by the reaction was removed from the system by azeotroping with toluene, After 2 hours, almost the theoretical amount of water was obtained.

After the reaction mixture was cooled to room temperature, it was poured into water and the produced solid substance was collected by filtration. The solid was dried overnight at 180 ° C. to obtain 44.4 g of a pale yellow solid (yield: 56%). This was passed through a 200-mesh sieve to obtain fine particles having a particle size of 74 μ or less.

When the number average molecular weight of this polymer was measured by gel permeation chromatography using a dimethylformamide solvent, it was 22000 in terms of polyethylene glycol. Further, the glass transition temperature was 232 ° C. according to a differential thermal analyzer. Furthermore, the imidization ratio is about 95%, and the amine terminal ratio is about 95%.
It was found from the NMR spectrum. (Example 5) A unidirectional prepreg having the following constitution was manufactured. The prepreg is manufactured by first preparing a prepreg consisting of the following reinforcing fibers and a matrix resin composition in which the weight fraction of the reinforcing fibers is 32%, and then, on one side thereof, the polyether synthesized in Reference Example 2 is prepared. It was carried out by uniformly dispersing the imide resin fine particles.

<Reinforcing fiber>: Toray Industries, Inc. carbon fiber “Torayca T800H-12K” (registered trademark) <Matrix resin composition>: N, N-bismaleimidediaminodiphenylmethane (manufactured by Ciba-Geigy, 5292A) 215 parts by weight N , N-bismaleimide tolylenediamine (manufactured by Mitsui Toatsu Co., Ltd., BMI-TDA) 113 parts by weight o, o-diallyl bisphenol A (manufactured by Ciba Geigy, 5292B) 246 parts by weight thermoplastic polyimide (manufactured by Ciba Geigy) 5218) 64 parts by weight <fine particles>: Polyetherimide resin fine particles obtained in Reference Example 113 113 parts by weight The weight fraction of the resin in the obtained prepreg was 36%. The amount of carbon fibers per unit area was 190 g / m 2.

This prepreg was sandwiched between two smooth Teflon plates, gradually heated to 150 ° C. over 7 days to be cured, and the cross section was observed. When the amount of fine particles present in the range from the prepreg surface to 30% of the thickness of the prepreg was evaluated, the value was 96%.

Next, 24 sheets of this prepreg are pseudo-isotropically laminated and molded by an ordinary autoclave at 190 ° C.
At a pressure of 6 kgf / cm ² for 4 hours. When the cross section was observed with an electron microscope after molding, it was found that a microphase-separated structure having a polyetherimide portion as a continuous phase was formed.

These cross-sections could be observed without dyeing with a dyeing agent. The pseudo isotropic hardened plate was cut into a length of 150 mm and a width of 100 mm, and a falling weight impact of 1500 inch-pounds / inch was applied to the center, and the damage area was measured with an ultrasonic flaw detector. It was inches. Then, according to ASTM D-695
The compressive strength after impact was measured and found to be 46 ksi. Further, when the damaged portion is observed with an optical microscope, it is as shown in FIG. 1, and it is understood that the path of the crack propagating between the layers is complicated and a large amount of energy is absorbed.

Next, using the same prepreg, one direction 16
A ply laminated plate is formed into a composite material having a thickness of about 2 mm, cut into a yarn length of 127 mm and a width of 1.9 mm, and pulled in a direction perpendicular to the fiber direction at a test length of 60 mm and a displacement speed of 2.5 mm / min. The test was conducted. The tensile strength at this time is
It was 9.3 kgf / mm ² .

[0096]

INDUSTRIAL APPLICABILITY The prepreg of the present invention can obtain high impact resistance and non-fiber shaft tensile strength when made into a composite while securing tackiness and drape property as the prepreg.

Further, while the adhesiveness and flexibility of the prepreg are ensured, a composite material is obtained in which the strength other than the direction of the reinforcing fibers, that is, the non-fiber axial tensile strength and the compressive strength after impact is remarkably improved. be able to.

[Brief description of drawings]

FIG. 1 is an optical micrograph (× 200) of a damaged part of the composite material of the present invention manufactured in Example 5, after measuring the compressive strength after impact.

FIG. 2 is an optical micrograph (2) of the damaged part after measuring the compressive strength after impact on the composite material produced in Comparative Example 1.
00 times).

Front page continuation (72) Inventor Yoshinobu Kubota 1515 Tsutsui, Matsumae-cho, Iyo-gun, Ehime Toray Co., Ltd. Ehime factory (72) Inventor Toshio Muraki 1515 Tsutsui, Matsumae-cho, Iyo-gun, Ehime Ehime factory

Claims (16)

[Claims] 1. A prepreg comprising the following constituents [A], [B], and [C], wherein 90% or more of [C] is 3 or more of the thickness of the prepreg on one side or both sides of the prepreg.
A prepreg characterized by being localized within a depth of 0%. [A]: Reinforcing fibers made of long fibers [B]: Matrix resin [C]: Fine particles made of thermoplastic resin soluble in [B] component 2. The prepreg according to claim 1, wherein the addition amount of the constituent element [C] is in the range of 1 to 50 parts by weight with respect to the constituent element [B]. 3. The prepreg according to claim 1, wherein the component [C] has a particle diameter of 150 μm or less. 4. The prepreg according to claim 1, wherein the constituent element [C] is fine particles made of a thermoplastic resin having an imide chain. 5. The prepreg according to claim 1, wherein the constituent element [C] is fine particles made of a thermoplastic resin having a silicone chain. 6. The prepreg according to claim 1, wherein the constituent element [C] is fine particles made of a thermoplastic resin having both an imide chain and a silicone chain. 7. The composition according to claim 2, wherein the constituent element [C] is fine particles composed of a polymer having a structure represented by the following formula [I] and having a number average molecular weight of 5,000 or more. The prepreg described in 3. [Chemical 1] 8. The prepreg according to claim 1, wherein the constituent element [B] is a mixture of a thermosetting resin and a thermoplastic resin. 9. The prepreg according to claim 8, wherein the thermosetting resin is an epoxy resin, a polymaleimide resin, a cyanate resin, a polyimide resin, or a mixture thereof. 10. The prepreg according to claim 8, wherein the thermoplastic resin is a polyimide resin. 11. The constituent element [C] is fine particles composed of an oligomer of a thermoplastic resin.
The listed prepreg. 12. A composite material comprising the following constituent elements [A], [B], and [L], wherein [L] is localized between laminated layers. [A]: Reinforcing fiber consisting of long fibers [B]: Matrix resin [L]: High toughness resin layer having a phase separation structure 13. The composite material according to claim 12, wherein the constituent [L] contains 20 to 90% by volume of the phase rich in the thermoplastic resin. 14. The thickness of the constituent element [L] is 5 of each layer thickness.
13. The composite material according to claim 12, wherein the composite material is about 50%. 15. The composite material according to claim 12, wherein the constituent element [L] has a phase-separated structure, and the phase rich in the thermoplastic resin is a continuous phase. 16. A composite material comprising the following constituent elements [A], [B] and [C], wherein 90% or more of [C] is 3 or more of the thickness of the prepreg on one side or both sides of the prepreg.
A composite material, which is formed by laminating prepregs localized within a depth range of 0%. [A]: Reinforcing fibers made of long fibers [B]: Matrix resin [C]: Fine particles made of thermoplastic resin soluble in [B] component