JPS63170428A - Production of prepreg - Google Patents

Abstract

PURPOSE:To obtain a prepreg having remarkably improved tensile strength in the direction other than the fiber axis direction, interlaminar strength, etc., while sustaining tackiness and flexibility, by combing a blend of a base resin and fine resin particles with a blend of the base resin and reinforcing filaments. CONSTITUTION:A base resin is blended with fine particles made of a resin as a material to prepare a blend. The base resin is blended with reinforcing fibers consisting of filaments to prepare a blend and both blends are then combined. An epoxy resin, particularly made from an aromatic amine represented by tetraglycidyldiaminodiphenylmethane as a precursor is preferred as the base resin. Polyamide, polyacetal, polyaramid, etc., are used as the fine resin particles and particle diameter thereof is 0.01-150mum, preferably 0.1-100mum.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an advanced composite material that is required to have high strength, high elastic modulus, and high specific strength and high specific elastic modulus, which are obtained by dividing these by specific gravity. The present invention relates to a method for manufacturing prepreg used in structures such as More specifically, while ensuring the adhesiveness and flexibility of the prepreg, the strength of the reinforcing fibers in directions other than the fiber axis,
In particular, the present invention relates to a prepreg manufacturing method that provides a structure with significantly improved non-W4 transverse tensile strength, interlaminar strength, interlaminar toughness, and impact resistance.

[Conventional technology] Advanced composite materials are non-uniform materials that have a reinforced IIi cloth and a matrix resin as essential components, and therefore there is a large difference between the physical properties in the fiber axis direction and the physical properties in other directions. do. For example, it is known that resistance to falling weight impact is controlled by delamination strength, and improving the strength of reinforcing fibers does not lead to substantial improvements. For this reason, in addition to improving the toughness of the matrix resin, with the aim of improving physical properties in directions other than the fiber axis direction,
Improvements have been proposed in various ways.

■LJSP 3,472,730 (1969) states that a separate exterior film (Separate Exterior Film) consisting of a thermosetting resin modified with an elastomeric substance on one or both sides of an m-fiber reinforced sheet is proposed.
) is disclosed to improve the interlayer peeling force.

■Japanese Patent Publication No. 51-58484 (Japanese Patent Publication No. 58-3129
6) discloses that moldability and bending strength can be improved by providing a polyether sulfone film on the surface of a fiber-reinforced epoxy resin prepreg.

■Unexamined Japanese Patent Publication No. 54-3879. Japanese Patent Publication No. 56-115216.
JP-A No. 60-44334 discloses that short fiber chips, chopped strands, and milled fibers are arranged between the layers of a fiber-reinforced sheet to improve the interlayer strength.

(1) JP-A-60-63229 discloses that interlaminar strength can be improved by disposing an epoxy resin film modified with an elastomer between the layers of fiber-reinforced prepreg.

■U.S.P. 4,539,253 (1985) (
In the corresponding Japanese Patent Application Laid-Open No. 6O-231738), a nonwoven fabric, woven fabric, mat, or a film made of a carrier impregnated with an epoxy resin modified with an elastomer is placed between the layers of fiber-reinforced prepreg, and a film made of a carrier impregnated with an epoxy resin modified with an elastomer is arranged between the layers of fiber reinforced prepreg. It is disclosed that an improvement in strength is achieved.

■U.S.P. 4,604,319 (1986) (
The corresponding Japanese Patent Application Laid-Open No. 60-231738 discloses that interlaminar strength is improved by disposing a thermoplastic resin film between the layers of fiber-reinforced prepreg.

These methods are not only insufficiently effective, but also have their own drawbacks. When using an independent outer layer film containing an elastomer-modified thermosetting resin, the heat resistance decreases when the elastomer content increases, and the effect of improving interlaminar strength is very small when the elastomer content is low.

In addition, when a thermoplastic resin film is used, it is possible to achieve both heat resistance and interlaminar strength improvement effects by using a thermoplastic resin film with good heat resistance, but the adhesiveness, which is an advantage of thermosetting resin, is Lost. Moreover, the general drawback of thermoplastic resins, such as poor solvent resistance, is reflected in the composite material.

Furthermore, the use of short aim chopped or chopped strand milled fibers increases the thickness of the interlayers, resulting in a decrease in the strength of the composite as a whole.

Note that JP-A-58-205758 discloses the effect of attaching thermoplastic resin powder to the surface of a sheet molding compound to facilitate surface protection and coloring. The effects are completely different. Furthermore, in Japanese Patent Publication No. 61-29265, a composite sheet with a thinner sheet material adhered to the outer layer of the sheet material is used to obtain a composite material with a good finished appearance, but this is also different from the present invention. , the effects are completely different.

[Problems to be Solved by the Invention] As a result of intensive studies to solve these problems, the present inventors have developed a prepreg that does not have the above drawbacks and provides a composite material with significantly improved physical properties. This led to the invention of a manufacturing method.

[Means for Solving the Problems] The present invention has the configuration as described in the claims section.

The element used as the component [A] in the present invention has a long ti
1. It is a reinforcing fiber made of M. The reinforcing fibers used in the present invention are fibers with good heat resistance and tensile strength that are generally used as advanced composite materials.

For example, the reinforcing fibers include carbon fibers, graphite fibers, organic high modulus fibers (such as aramid fibers), silicon carbide fibers, alumina fibers, boron fibers, tungsten carbide V7A fibers, and glass fibers. Only one type of such reinforcing fibers may be used for the same prepreg, or different types of reinforcing fibers may be used regularly.
Or they may be used in irregular rows. Usually specific strength,
Although unidirectional prepreg is most suitable for applications requiring a high specific modulus, it is also possible to use pre-processed prepregs such as sheet forms such as long fiber mats and woven fabrics, and braided cords.

The element used as component [B] in the present invention is a base resin.

Base resins used in the present invention include thermosetting resins and resins in which thermosetting resins and thermoplastic resins are mixed.

The thermosetting resin used in the present invention is not particularly limited as long as it is a resin that can be cured by heat or external energy such as light or an electron beam to at least partially form a three-dimensional cured product. Preferred thermosetting resins include epoxy resins, maleimide resins, polyimide resins, resins with acetylene ends, resins with vinyl ends, resins with allyl ends, resins with nadic acid ends, and resins with cyanate ester ends. can give. These can generally be used in combination with a curing agent or a curing catalyst. Moreover, it is also possible to use a mixture of these thermosetting resins as appropriate.

Epoxy resin is used as a thermosetting resin suitable for the present invention. Particularly preferred are epoxy resins whose precursors are amines, phenols, and compounds having carbon-carbon double bonds. Specifically, various isomers of tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, triglycidyl-m-aminophenol, and phenols are used as epoxy resins using amines as precursors. As the epoxy resin used as a precursor, bisphenol A type epoxy resin,
Bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin,
Examples of the cresol novolak type epoxy resin and the epoxy resin whose precursor is a compound having a carbon-carbon double bond include, but are not limited to, alicyclic epoxy resins.

Brominated epoxy resins obtained by brominating these epoxy resins may also be used. Epoxy resins whose precursors are aromatic amines such as tetraglycidyldiaminodiphenylmethane are most suitable for the present invention because they have good heat resistance and good adhesion to reinforcing fibers.

Epoxy resins are preferably used in combination with epoxy curing agents. Any compound having an active group capable of reacting with an epoxy group can be used as the epoxy curing agent. Preferably, compounds having an amino group, an acid anhydride group, or an azide group are suitable. Specifically, dicyandiamide, various isomers of diaminodiphenylsulfone, and aminobenzoic acid esters are suitable. To explain specifically,
Dicyandiamide is preferably used because it has excellent pre-preg stability. Further, various isomers of diaminodiphenylsulfone are most suitable for the present invention because they give cured products with good heat resistance. As aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used, and although they have inferior heat resistance compared to diaminodiphenylsulfone, they have good tensile strength. To excel,
It is selected and used depending on the purpose.

In the present invention, it is also suitable to use a mixture of the above thermosetting resin and a thermoplastic resin as the matrix resin.

Thermoplastic resins suitable for the present invention include carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds, urea bonds, thioether bonds, sulfone bonds, imidazole bonds, and carbonyl bonds in the main chain. A thermoplastic resin having a bond selected from, more preferably polyacrylate, polyamide,
It is a group of thermoplastic resins belonging to engineering plastics such as polyaramid, polyester, polycarbonate, polyphenylene sulfide, polybenzimidazole, polyimide, polyetherimide, polysulfone, polyether sulfone, and polyether ether ketone. In particular, polyimide, polyetherimide, polysulfone, polyether sulfone, and polyether ether ketone are optimal for the present invention because they have excellent heat resistance.

As these thermoplastic resins, commercially available polymers may be used, or so-called oligomers having a lower molecular weight than commercially available polymers may be used. As the oligomer, an oligomer having a functional group capable of reacting with the thermosetting resin at the terminal or in the molecular chain is more preferable.

An example of using an oligomer that has a functional group at the end or in the molecular chain that can react with a thermosetting resin is an oligomer that has an aromatic amine at the end as a functional group and a backbone of polysulfone, polyethersulfone, or polyetherketone. There are examples of JP-A-60-154206 and JP-A-Sho [>1-212].
543 and JP-A-Sho fly1-212544. J, E, HcGrath et al. also attended the 31st Sambe Symposium (31th 5AHPE (198B
)580). Also, JP-A-61-228
A similar example is also shown in 016. According to these results, it can be seen that all cured products have good heat resistance and high toughness. In addition, examples of having an aromatic amine at the end as a functional group and having a polysulfone skeleton are shown in JP-A-58-134111 and JP-A-59-36127, and J.E., HcGrath et al. Symposium (30th 5AHPE (1985) 947
) has been announced. These results indicate that a cured product with good heat resistance and high toughness was obtained.

Thus, mixtures of thermosetting resins and thermoplastic resins give better results than when thermosetting resins are used alone. This is because thermosetting resins generally have the disadvantage of being brittle but can be molded at low pressure using an autoclave, whereas thermoplastic resins have the advantage of being tough but are difficult to mold at low pressure using an autoclave. This is because they exhibit contradictory properties, so by mixing and using them, it is possible to balance physical properties and moldability.

Moldability is expressed most simply by the lowest viscosity of the resin composition during the temperature rising process. The lower limit of the minimum viscosity suitable for prepreg cannot be generally defined, as it varies significantly depending on the resin content in the prepreg, the number of layers, the curing method, and the curing conditions (temperature, pressure), but when molding using an autoclave,
Generally, 1 poise or more, more preferably 10 poise or more is suitable, and as the number of laminated sheets increases, a resin system with a higher minimum viscosity (for example, 10 to 100 poise) becomes optimal.

The viscosity during the heating process can be measured using a cone-plate rotational viscometer or a B-type viscometer. Generally, a suitable temperature increase rate is 0.5 to 5°C, but since changing the temperature increase rate also changes viscosity behavior, measurements are generally made at a temperature increase rate of 1 to 2°C per minute.

According to the above, the thermoplastic resin component is 0 to 50% by weight, more preferably 0 to 50% by weight based on 100 parts by weight of the matrix resin.
It is 30% by weight.

Component [C] needs to be fine particles made of either a thermoplastic resin, a thermosetting resin, or both.

Since fine particles exist in a dispersed state in the base resin when mixed with the base resin, the characteristics of the base resin appear to be dominant in the matrix resin, and even when impregnated into reinforcing fibers, the properties of the base resin are Adhesion and deformability (
It is possible to obtain a prepreg that maintains drapability) and has excellent handling properties. Therefore, since adhesiveness and deformability (drapeability) are not required as characteristics of the fine particles, there is a wide range of materials that can be selected for the fine particles.

For this reason, even resins that have conventionally been difficult to use as matrix resins despite their superior performance can be made into fine particles and used as constituent components of matrix resins, improving the performance of matrix resins. be able to.

The thermosetting resin used as fine particles refers to all resins that are cured by heat or external energy such as light or electron beams to at least partially form a three-dimensional crosslinked body. Preferred thermosetting resins include epoxy resins, phenolic resins, unsaturated polyester resins, amino resins,
Allyl resin, silicone resin, urethane resin, maleimide resin, polyimide resin, resin with acetylene end, resin with vinyl end, resin with allyl end,
Resins with nadic acid ends and resins with cyanate ester ends are included. As a commercially available thermosetting resin fine particle, for example, the epoxy resin Torepar EP-B manufactured by Toshiki Co., Ltd. is used.

Examples include phenolic resin Belval R-800 manufactured by Kanebo. Furthermore, even if fine particles cannot be obtained as a commercial product, it is possible to make them into fine particles by crushing the above-mentioned resin, and by further classification, it is possible to use only particles within the desired particle size range. Can be done.

It is also suitable for the present invention to use a thermoplastic resin as the fine particles. Thermoplastic resins suitable for the present invention include carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds,
The thermoplastic resin has a bond selected from a urea bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond, but may have a partially crosslinked structure within the molecule. Specifically, vinyl resins such as polyacrylate, polyvinyl acetate, and polystyrene, polyamide, polyaramid, polyester,
Polyacetal, polycarbonate, polyphenylene oxide, polyphenylene sulfide, polyarylate,
Thermoplastic resins belonging to engineering plastics such as polybenzimidazole, polyimide, polyamideimide, polyetherimide, polysulfone, polyethersulfone, and polyetheretherketone; hydrocarbon resins represented by polyethylene and polypropylene;
Examples include cellulose derivatives represented by cellulose acetate and cellulose wI acid.

In particular, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide,
Polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polyaramid, and polybenzimidazole have excellent impact resistance and are therefore suitable as materials for the fine particles used in the present invention.

Among these, polyamide has particularly excellent toughness, and by using a polyamide that belongs to the amorphous transparent nylon category, it can also have heat resistance. Commercially available thermoplastic resin fine particles include, for example, nylon 12 fine particles 5P-500 manufactured by Toshishi Corporation, and acrylic fine particles MP-1000 manufactured by Japan Synthetic Rubber ■. Furthermore, even if fine particles cannot be obtained as a commercial product, it is possible to make them into fine particles by crushing the above-mentioned resin, and by further classification, it is possible to use only particles within the desired particle size range. Can be done.

It is also suitable to use a mixture of a thermosetting resin and a thermoplastic resin as the fine particles. Suitable thermosetting resins and thermoplastic resins in this case are the same as those mentioned above. For example, if a mixture of a phenol resin and a nylon resin is used, the water absorption rate of the nylon resin is lowered and To is increased while maintaining the toughness of the nylon resin, so that a particle component with excellent heat and water resistance can be obtained.

Regarding the distribution of the fine particles, it is preferable that they exist in the surface layer of the prepreg, that is, in the space between the prepreg sheets when molded into a composite material.

In highly anisotropic materials such as composite materials, uniform stress is rarely generated throughout the material, and in most cases stress is concentrated in specific areas. In particular, in the case of fiber-reinforced composite materials obtained by laminating sheet-like prepregs, it is known that when an external force such as an external impact force is applied, a large stress is applied between the sheets, that is, between the layers. Therefore, when fine particles with excellent toughness are distributed between the layers at a relatively high concentration, a remarkable effect is brought about in improving the interlayer toughness.

In particular, when trying to improve the interlayer toughness, a method disclosed in JP-A-60-231738 is characterized in that a clearly separated film layer containing a thermoplastic resin as a main component is provided on one side or the top of the prepreg. However, the fine particles used in the present invention do not require the formation of such a separation layer. lIi￥/1 The internal stress that occurs when a reinforced composite material is subjected to strain such as an impact has a distribution in the direction perpendicular to the layers, centered between the layers, and is rather clearly defined by the presence of fine particles that match the distribution. The modification effect and reinforcing effect are greater if they are not separated.

In other words, the greatest feature of the composite material realized here is that materials with unique properties are placed in appropriate locations, and the matrix resin is a hybrid of the base resin and fine particle components. That's true.

Furthermore, the major difference from the case of JP-A-60-231738 is that JP-A-60-231,738 has a separation film layer, which reduces the adhesiveness of the prepreg.
In contrast, the present invention does not have such problems at all, whereas it has drawbacks such as the inability to increase the fiber content when made into a composite material.

The shape of the fine particles used in the present invention is not limited to spherical. Of course, it may be spherical, but it may be in a variety of shapes, such as fine powder obtained by crushing a resin lump, or fine particles obtained by a spray drying method or a reprecipitation method. In addition, it may be in the form of milled fibers obtained by cutting the fibers into short lengths, or may be in the form of needles or whiskers. Especially when it is desired to use spherical particles, products obtained by suspension polymerization can be used as is.

The size of fine particles is expressed by the particle size, and the particle size in this case means the volume average particle size determined by a centrifugal sedimentation velocity method or the like.

The particle size of the fine particles used in the present invention is o, oiμm to 150μm.
m, more preferably in the range of 0.1 to 100 μm. Reinforcement 11 if the particle size exceeds 150μm
This has the disadvantage that it disturbs the arrangement of iIft and makes the interlayers of the composite material obtained by stacking it thicker than necessary, which deteriorates the physical properties of the composite material. However, even fine particles with a particle size exceeding 150 μm may be partially dissolved in the base resin during molding and become smaller, or they may be deformed by heating during molding, causing gaps between filaments and layers of composite materials to form. There are also materials that can be made narrower and can be used as appropriate.

Fine particles may retain their original shape or may lose their shape after molding, but each has its advantages and disadvantages, and can be used depending on the purpose. When the fine particles are a thermosetting resin, there is not much difference in the effects among the above, but when the fine particles are a thermoplastic resin, the following effects are produced. Moreover, the difference is particularly noticeable in structures where fine particles are concentrated at high concentrations in specific areas, such as between the layers of a composite material.

In other words, if the original shape is maintained, the fine particles of the thermoplastic resin component will be isolated and dispersed, so the deterioration when coming into contact with organic solvents and the creep phenomenon under continuous loading, which are disadvantages of thermoplastic resin, will occur throughout the matrix resin. A composite material with excellent solvent resistance and creep resistance can be obtained. However, if the affinity between the base resin and the fine particles is extremely poor, peeling between the base resin and the fine particles may occur when stress is generated, and this may become a defect in the material. In this sense, it is preferable that there is some degree of partial compatibility or reactivity between the base resin and the fine particles.

On the other hand, if the particle shape disappears after molding, there is a concern that the fine particles of the thermoplastic resin component will be integrated to some extent and form a continuous part, resulting in a decrease in solvent resistance or creep resistance. However, the adhesion between the base resin and the fine particles is sufficiently strong, and a good composite material can be obtained in which the two do not peel off when stress is generated.

A suitable amount of fine particles is in the range of 0.1% to 80% by weight based on the matrix resin.

If the amount is less than 1% by weight, the effect of the fine particles will hardly be exhibited, and if it exceeds 80% by weight, it will be difficult to mix with the base resin, and the adhesiveness as a matrix resin will decrease significantly.

In particular, if the rigidity of the base resin is used to develop the compressive strength of the composite material while using fine particles that have a high elongation at break and flexibility, and are used for the purpose of increasing the toughness between the layers of the composite material, it is preferable to % to 20% by weight is preferred.

The prepreg manufacturing method according to the present invention involves first producing a mixture of component [B], that is, base resin, and component [C], that is, fine particles, and then reinforcing component [A], that is, made of long fibers. This is a manufacturing method by combining fibers and a mixture of prepreg made of component [B].

There are no particular limitations on the method for manufacturing prepreg made of reinforcing fibers and base resin, and all conventional methods for manufacturing prepreg are applicable.

For example, sheets coated with resin in advance are stacked on both sides of reinforcing fibers arranged parallel to each other in a sheet shape, and the resulting stack is heated and pressurized with an impregnated roll to transfer the resin of the resin-coated sheet to the reinforcing fibers. The reinforcing fibers arranged parallel to each other in a sheet form are immersed in a resin solution diluted with an appropriate solvent, pulled up, and heated to remove the solvent moderately or completely. etc. apply.

There are two methods for preparing a mixture of base resin and fine particles: one method is to mix the base resin and fine particles in advance with a stirrer such as a kneader, then coat it on release paper, etc. to make a resin coating film containing fine particles. There is a method in which a resin coating film is made in advance and fine particles are sprinkled onto it using an appropriate method.

When the particle size of the fine particles is large, the latter method is preferable because it is difficult to make a thin coating film using the former method. There are no particular limitations on the method for producing the resin coated film, and all conventionally known coating methods are applicable.

Regarding the method of combining a prepreg made of a reinforced 41i base resin and a resin coating film made of a base resin, it is possible to simply overlay a coating film on both sides or only one side of the prepreg, or after that, use an impregnated roll etc. It may be impregnated into the prepreg appropriately by heating and pressurizing. Furthermore, by adjusting the degree of impregnation, it is also possible to control the tackiness of the prepreg surface.

[Function] The reinforcing fiber of the present invention is the most central component responsible for the strength of the composite material. While the base resin provides adhesiveness and flexibility in the prepreg state, it retains the rigidity of the entire matrix resin after curing. The fine particles alleviate the internal stress that occurs when the fiber-reinforced composite material is subjected to impact or other strain by being concentrated on the surface layer of the prepreg without impairing the adhesiveness and flexibility provided by the base resin. It has the effect of delaying fracture under stress and changing from a brittle fracture mode to a highly tough fracture mode. This effect of the fine particles is thought to be mainly due to the large tolerance of the fine particle components themselves, their adhesion to the base resin, or their distribution pattern in the matrix resin.

The prepreg manufacturing method of the present invention can easily cause fine particles to be biased toward the surface layer of the prepreg, regardless of the shape, particle size, amount, etc. of the fine particles.

[Example] The invention will be explained in further detail by the following examples.

The amounts of each component in the examples represent parts by weight, and the contents of the epoxy resin additive, fine particles, and curing agent are as follows.

Epoxy A: N, N, N-, N''-tetraglycidyldiaminodiphenylmethane, ELM43 manufactured by Sumitomo Chemical Co., Ltd.
4 Epoxy B: Bisphenol F type epoxy resin, Epiclon 830 manufactured by Dai-Nippon Ink & Chemicals Co., Ltd. Epoxy C: Bisphenol A type epoxy resin, EP825 manufactured by Yuka Shell Epoxy ■ Additive: Polyether sulfone, VICTREXPES500 manufactured by Imperial Chemical Industries
3P Hardening agent Nidiaminodiphenylsulfone, fine particles A: Nylon 12, 5P-500 manufactured by Toshi ■ (average particle size 5 μm) Fine particles B: Phenol resin, Belval R-8 manufactured by Kanebo ■
00 Example 1 15 parts of additives were added to 810 parts of epoxy and 810 parts of epoxy, and the mixture was stirred in a kneader at 150°C for 2 hours. Thereafter, it was cooled to 60°C, 35 parts of hardening agent A was added, and 30 parts of curing agent A was added.
The base resin was obtained by stirring for a minute. This base resin was coated on a release paper to obtain a base resin film having a basis weight of 20a/rd. Next, this base resin film was superimposed on both sides of reinforcing fibers made of carbon fiber "Trading Card" Ta2O made by Toshiki II and aligned in one direction.
A base prepreg was obtained by applying pressure with a linear pressure of 5k11/CIR using an impregnating roll heated to 0°C to impregnate the base resin. The CF basis weight of the pace prepreg at this time was 152q/T.
It was d.

Next, 150 parts of the above base resin was stirred with 32 parts of fine particles A for 30 minutes in a kneader heated to 60°C to obtain a mixture of fine particles and base resin. Next, this mixture was coated on release paper to obtain a film consisting of a mixture of resin and fine particles with a basis weight of 15 g/bottom. Films made of this mixture were superimposed on both sides of the base prepreg, and pressed with an unheated roll having an outer diameter of 100 mm at a linear pressure of 2 kg/α to obtain a prepreg. This prepreg had a sticky surface and good drapability.

48 pieces of the obtained prepreg were laminated in a quasi-isotropic manner and molded in an autoclave at 6@/cti and 180° C. for 2 hours to obtain a cured plate with a thickness of about 6.8 mm. Cut this hardened board into 250mm x 125mm, 1
A falling weight impact energy of 0.000 bond inches/inch was applied. The damage caused by this impact test was measured using an ultrasonic flaw detection imaging device model M400B manufactured by Canon/Holonics.

The damaged area is shown in Table 1. Next, the hardened plate subjected to this impact was subjected to a compressive strength test according to NASARP1092. Table 1 shows the compressive strength after impact.

Example 2.3 A prepreg was produced using the resin composition shown in Table 2 in the same manner as in Example 1, and the physical properties of the cured plate were measured. The results are shown in Table 1.

Comparative Example 1 A paste prepreg was prepared using the resin composition shown in Table 2 in the same manner as in Example 1, except that the basis weight of the base resin film was 35q/T112. A cured plate was prepared in the same manner as in Example 1 (without overlapping the films), and its physical properties were measured. -The results are shown in Table 1.

Comparative Example 2 A base resin was prepared using the same method as in Example 1 for the resin composition shown in Table 2, and fine particles A were added to 150 parts of the base resin.
12 parts (the ratio of fine particles to the entire resin when made into a prepreg is 7.5%) was added, and the mixture was stirred at 60° C. for 30 minutes. This mixture of resin and fine particles was made into a film of 35 g/77f, and the film was replaced with the base resin film of Example 1 to produce a prepreg in the same manner as the paste prepreg of Example 1. A cured product was prepared using this method, and its physical properties were measured. The results are shown in Table 1.

From the physical properties of the cured plates listed in Table 1, it was confirmed that the compressive strength after impact was significantly improved compared to the comparative example, as is clear in Examples 1 to 3.

Table 1 Table 2 [Effects of the invention] The prepreg of the present invention in which the fine particles are concentrated on the surface layer has high compression, tensile and bending properties when made into a fiber-reinforced composite material while ensuring the adhesiveness and flexibility of the prepreg. Greater toughness than traditional fiber-reinforced composites that do not contain particulates, offering strength and the ability to withstand impact damage.
It has shear cutting impact resistance, impact damage resistance and crack growth resistance.

Furthermore, the composite material obtained by 1q according to the present invention has a remarkable effect not only on the above-mentioned properties but also on improving the 90' tensile elongation at break and the strength of the unidirectionally reinforced material.

The method for producing a prepreg of the present invention can easily produce a prepreg in which the fine particles having the above characteristics are concentrated on the surface layer of the prepreg, regardless of the nature of the particles.

Claims (1)

[Claims] (1) When manufacturing a prepreg that requires the following components [A], [B], and [C], a mixture of component [B] and component [C], and component [A] Component[
A method for producing prepreg, which comprises preparing the mixed product of [B] and then combining both mixed products. [A]: Reinforced fiber made of long fibers [B]: Base resin [C]: Fine particles made of resin