JP5796287B2 - Epoxy resin composition for fiber reinforced composite material, prepreg and honeycomb sandwich panel using the same - Google Patents

Description

  The present invention relates to an epoxy resin composition for fiber-reinforced composite materials, a prepreg and a honeycomb sandwich panel using the same.

  In self-adhesive prepregs that can improve panel productivity without applying film adhesive during the manufacture of honeycomb panels, increasing the toughness of the matrix resin and resin flow characteristics are extremely important. Conventionally, rubber or super engineering plastics (heat Investigation of toughness of an epoxy resin by a plastic resin is underway (see, for example, Patent Documents 1 to 8).

International Publication No. 99-02586 International Publication No. 2005-83002 JP 2006-328292 A JP 2006-198920 A US Patent Application Publication No. 2002/0079052 JP 2005-506394 A JP 2006-291218 A JP 2001-31838 A

However, in the compounding system using liquid rubber, the molecular weight of the rubber itself is small, so that even if a large amount is added, the epoxy resin cannot be sufficiently toughened.
Further, in order to develop sufficient self-adhesiveness, it is necessary to add 40 to 50 parts by weight or more of an engineering plastic (thermoplastic resin) to 100 parts by weight of the epoxy resin, and the engineering plastic in the phase structure of the cured resin is a continuous phase. The present inventors have found that when the cured resin is exposed to a solvent, the engineering plastic continuous phase is easily affected by the solvent, resulting in a decrease in the solvent resistance of the composite material. .
Then, an object of this invention is to provide the epoxy resin composition for fiber reinforced composite materials used as the hardened | cured material excellent in toughness and solvent resistance.

  As a result of earnest research to solve the above problems, the present inventor contains an epoxy resin A, a thermoplastic resin B, an adsorption filler in which the thermoplastic resin C is adsorbed on the filler, and a curing agent, and has a specific formula. Satisfying that the adsorption coefficient defined by is greater than 0 and less than or equal to 0.8, and after curing, at least the epoxy resin A forms a continuous phase, and the adsorbent filler is dispersed in at least the continuous phase. The present inventors have found that the epoxy resin composition for fiber reinforced composite materials is an epoxy resin composition for fiber reinforced composite materials that is a cured product having excellent toughness and solvent resistance.

That is, this invention provides the following 1-19.
1. Containing an epoxy resin A, a thermoplastic resin B, an adsorption filler in which the thermoplastic resin C is adsorbed on the filler, and a curing agent;
Satisfying that the adsorption coefficient defined by the following (formula 1) is greater than 0 and 0.8 or less,
The epoxy resin composition for fiber-reinforced composite materials in which at least the epoxy resin A forms a continuous phase and the adsorbent filler is dispersed in at least the continuous phase.
(Formula 1)
Adsorption coefficient = Amount of the thermoplastic resin C adsorbed on 100 parts by mass of the filler (mass part) / Specific gravity of the thermoplastic resin C / DBP oil absorption of the filler (mL / 100 g)
2. 2. The epoxy resin composition for fiber-reinforced composite material according to 1 above, wherein the epoxy resin A contains an epoxy resin a-1 having a viscosity at 25 ° C. of 2,000 mPa · s or less.
3. 3. The epoxy resin composition for fiber-reinforced composite material according to 1 or 2 above, wherein the shape of the filler is at least one selected from the group consisting of spherical, granular and irregular shapes.
4). 4. The epoxy resin composition for fiber-reinforced composite material according to any one of 1 to 3, wherein the filler is at least one selected from the group consisting of fumed silica, carbon black, and carbon nanotubes.
5. The epoxy resin composition for fiber-reinforced composite materials according to any one of the above 1 to 4, wherein the thermoplastic resin B or the thermoplastic resin C is at least one selected from the group consisting of polyethersulfone and polyetherimide. .
6). The epoxy resin composition for fiber-reinforced composite materials according to any one of 1 to 5 above, wherein the amount of the adsorption filler is 0.1 to 100 parts by mass with respect to 100 parts by mass of the epoxy resin A.
7). The epoxy resin composition for fiber-reinforced composite materials according to any one of 1 to 6, wherein the thermoplastic resin B or the thermoplastic resin C has a functional group that reacts with the epoxy resin A.
8). The epoxy resin composition for fiber-reinforced composite materials according to any one of 1 to 7 above, wherein the DBP oil absorption is 10 to 1,000 mL / 100 g.
9. Furthermore, the epoxy resin composition for fiber-reinforced composite materials according to any one of 1 to 8 above, which contains a solid resin D and / or an elastomer that is solid at normal temperature.
10. 10. The epoxy resin composition for a fiber-reinforced composite material according to 9, wherein the solid resin D is at least one selected from the group consisting of an epoxy resin d-1, a maleimide resin, a cyanate resin, and a resin having a core-shell structure.
11. The fiber reinforcement according to 10 above, wherein the epoxy resin d-1 is at least one selected from the group consisting of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a phenoxy skeleton type epoxy resin having an epoxy group at a molecular end. Epoxy resin composition for composite materials.
12 12. The epoxy resin composition for fiber-reinforced composite materials according to any one of 1 to 11 above, wherein the minimum viscosity by dynamic viscoelasticity measurement at a temperature rising rate of 2 ° C./min is 1 to 100 Pa · s.
13. 13. The epoxy resin composition for fiber-reinforced composite materials according to any one of 1 to 12 above, wherein the viscosity at 50 ° C. measured by dynamic viscoelasticity at a temperature rising rate of 2 ° C./min is 5000 Pa · s or less.
14 The fracture toughness value measured according to ASTM D5045 using the obtained cured product after curing of the epoxy resin composition for fiber-reinforced composite material according to any one of 1 to 13 above is 1.8 MPa√ The epoxy resin composition for fiber-reinforced composite materials according to any one of 1 to 13 above, which is m or more.
15. A prepreg obtained by combining the epoxy resin composition for fiber-reinforced composite material according to any one of 1 to 14 above and a reinforcing fiber.
16. 16. The prepreg according to 15 above, wherein the content of the epoxy resin composition for fiber-reinforced composite material is 30 to 60% by mass in the prepreg.
17. The prepreg as described in 15 or 16 above, wherein the reinforcing fiber is a carbon fiber.
18. A honeycomb sandwich panel obtained by laminating and curing the prepreg according to any one of 15 to 17 above and a honeycomb core.
19. 19. The honeycomb sandwich panel according to the above 18, wherein the honeycomb core is at least one selected from the group consisting of an aramid honeycomb, an aluminum honeycomb, a paper honeycomb, and a glass honeycomb.

  The epoxy resin composition for fiber-reinforced composite materials of the present invention becomes a cured product having excellent toughness and solvent resistance. The prepreg of the present invention and the honeycomb sandwich panel of the present invention are excellent in toughness and solvent resistance.

FIG. 1 is a perspective view schematically showing an example of the honeycomb sandwich panel of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a cross section obtained by cutting the honeycomb sandwich panel in parallel with the side surfaces of the prisms of the honeycomb core.

The present invention will be described in detail below.
The epoxy resin composition for fiber-reinforced composite material of the present invention is
Containing an epoxy resin A, a thermoplastic resin B, an adsorption filler in which the thermoplastic resin C is adsorbed on the filler, and a curing agent;
Satisfying that the adsorption coefficient defined by the following (formula 1) is greater than 0 and 0.8 or less,
The form after curing is a composition in which at least the epoxy resin A forms a continuous phase and the adsorbent filler is dispersed in at least the continuous phase.
(Formula 1)
Adsorption coefficient = Amount of the thermoplastic resin C adsorbed on 100 parts by mass of the filler (mass part) / Specific gravity of the thermoplastic resin C / DBP oil absorption of the filler (mL / 100 g)
The epoxy resin composition for fiber-reinforced composite materials of the present invention may be hereinafter referred to as “the composition of the present invention”.

The epoxy resin A will be described below.
The epoxy resin A contained in the fiber reinforced composite material epoxy resin composition of the present invention is not particularly limited as long as it is a compound having two or more epoxy groups. For example, a conventionally well-known thing is mentioned.

  The epoxy resin A contains an epoxy resin a-1 having a viscosity of 2,000 mPa · s or less by an E-type or B-type viscometer at 25 ° C. from the viewpoint of excellent handling workability such as resin impregnation into a reinforcing fiber. And more preferably 100 to 2,000 mPa · s.

  Examples of the epoxy resin a-1 include glycidylamine type epoxy resins such as tetraglycidyl-m-xylylenediamine and 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane; triglycidyl-p-amino. Aminophenol type epoxy resin such as phenol and triglycidyl-p-aminocresol; Resorcinol type epoxy resin such as diglycidyl resorcinol; Glycidyl ester type epoxy resin such as diglycidyl hexahydrophthalate and diglycidyl tetrahydrophthalate .

Among these, the epoxy resin a-1 is superior in heat resistance, toughness, and solvent resistance, and is excellent in handling workability such as resin impregnation into a reinforced fiber. From the viewpoint of aminophenol type epoxy resin and resorcinol type epoxy resin. Is preferred.
Epoxy resin a-1 can be used individually or in combination of 2 types or more, respectively.

The epoxy resin A can further include an epoxy resin a-2 having a viscosity at 25 ° C. exceeding 2,000 mPa · s from the viewpoint of excellent toughness and solvent resistance.
The viscosity at 25 ° C. of the epoxy resin a-2 is 10,000 mPa · s or less from the viewpoint of being excellent in toughness and solvent resistance and not adversely affecting handling workability such as resin impregnation into the reinforcing fiber. Is more preferable.

  Examples of the epoxy resin a-2 include bifunctional glycidyl ether types such as bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, and biphenyl type. Epoxy resin; Polyglycidyl ether type epoxy resin; Glycidyl ester type epoxy resin of synthetic fatty acid such as dimer acid; Fragrance having glycidylamino group such as N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane (TGDDM) Epoxy resin; alicyclic epoxy resin; epoxy resin having sulfur atom in epoxy resin main chain; urethane-modified epoxy resin having urethane bond; polybutadiene, liquid polyacrylonitrile-butadiene rubber or acrylonitrile butadiene Rubber-modified epoxy resin containing a beam (NBR).

Among these, the epoxy resin a-2 is preferably a bisphenol A type epoxy resin or a bisphenol F type epoxy resin from the viewpoint of workability and heat resistance of the cured product.
The epoxy resin a-2 can be used alone or in combination of two or more.

  The amount of the epoxy resin a-1 is 30 to 100% by mass in the epoxy resin A from the viewpoint of being excellent in heat resistance, toughness and solvent resistance and excellent in handling workability such as resin impregnation into a reinforcing fiber. It is preferable that it is 50 to 100 parts by mass.

The thermoplastic resin B will be described below.
The thermoplastic resin B contained in the epoxy resin composition for fiber-reinforced composite material of the present invention is not particularly limited.
The epoxy resin composition for fiber-reinforced composite material of the present invention contains the thermoplastic resin B, so that the viscosity and thixotropy of the composition can be made appropriate, thereby the epoxy for fiber-reinforced composite material of the present invention. The resin composition can form a good fillet and have excellent prepreg self-adhesiveness.
Examples of the thermoplastic resin B include polyethersulfone, polysulfone, polyetherimide, polyethylene terephthalate, polybutylene terephthalate, polyphenylene oxide, and polycarbonate.

  Among these, from the viewpoint of a good balance of mechanical properties (particularly toughness), heat resistance, and solvent resistance, the thermoplastic resin B is at least one selected from the group consisting of polyethersulfone and polyetherimide. Is preferred.

Moreover, it is preferable that the thermoplastic resin B has a functional group that reacts with the epoxy resin from the viewpoint of being excellent in mechanical properties and being excellent in toughness and solvent resistance among the above properties.
Examples of the functional group include a hydroxy group, an amino group, an imino group, an aldehyde group, a carboxy group, an epoxy group, and an isocyanate group.
The functional group possessed by the thermoplastic resin B is preferably a hydroxy group, an amino group, an epoxy group, or an isocyanate group from the viewpoint of being superior in toughness and solvent resistance among the above properties.

  The thermoplastic resin B has a UCST (upper critical solution temperature) or LCST (lower critical solution temperature) in the epoxy resin A from the viewpoint of a good balance of mechanical properties (particularly toughness), heat resistance, and solvent resistance. Preferably, the polymer has

The weight average molecular weight of the thermoplastic resin B is 20,000 to 100,000 from the viewpoint that the mechanical properties (particularly toughness), heat resistance, and solvent resistance are well balanced and the viscosity of the resin composition is not increased more than necessary. 000 is preferred.
The shape of the thermoplastic resin B is preferably in the form of particles from the viewpoint of excellent dissolution workability in the epoxy resin A. The average particle diameter of the thermoplastic resin B is preferably 200 μm or less from the viewpoint of excellent dissolution workability in the epoxy resin A.
The thermoplastic resins B can be used alone or in combination of two or more.

  The amount of the thermoplastic resin B is preferably 5 to 40 parts by mass with respect to 100 parts by mass of the epoxy resin A from the viewpoint of a good balance between mechanical properties (particularly toughness), heat resistance and solvent resistance. 10 to 30 parts by mass is more preferable.

The adsorption filler will be described below.
The adsorption filler contained in the epoxy resin composition for fiber-reinforced composite material of the present invention is obtained by adsorbing the thermoplastic resin C on the filler.
In the present invention, the adsorption refers to a phenomenon in which the concentration of the thermoplastic resin C becomes larger than the inside of the epoxy resin at the interface between the epoxy resin and the filler. Adsorption includes physical adsorption and chemical adsorption. From the viewpoint of promoting partial adsorption on the filler surface, physical adsorption is preferred.
The epoxy resin composition for fiber-reinforced composite materials of the present invention contains an adsorbent filler, so that it has excellent toughness and solvent resistance, can impart thixotropy to the composition and control the resin flow. Further, the amount of the thermoplastic resin B can be suppressed and the solvent resistance can be improved.

The filler will be described below.
In the epoxy resin composition for fiber-reinforced composite material of the present invention, the filler used when producing the adsorbent filler is not particularly limited. For example, an inorganic filler and an organic filler are mentioned. An inorganic filler is preferable from the viewpoint of superior toughness.
Examples of the inorganic filler include carbon black, silica (for example, fumed silica, wet silica), carbon nanotube, silica sand, calcium silicate, mica, talc, alumina, montmorillonite, aluminum nitride, boron nitride, calcium carbonate, and oxidation. Titanium is mentioned.
Among these, at least one selected from the group consisting of fumed silica, carbon black, and carbon nanotubes is preferable from the viewpoint of excellent toughness and solvent resistance and easy adsorption of the thermoplastic resin.

  The shape of the filler is not particularly limited. For example, the thing of spherical shape, a granular form, and an irregular shape (thing which has an irregular shape, an irregular shape) is mentioned. The shape of the filler is preferably at least one selected from the group consisting of spherical, granular, and irregular shapes from the viewpoint that the thermoplastic resin is easily adsorbed.

In the present invention, the DBP oil absorption (dibutyl phthalate oil absorption) of the filler is preferably 10 to 1,000 mL / 100 g from the viewpoint of adsorbing a sufficient amount of the thermoplastic resin C, and preferably 50 to 500 mL / More preferably, it is 100 g.
The average primary particle size of the filler is preferably 5 to 100 nm from the viewpoint of improving the adsorptivity of the thermoplastic resin.
The fillers can be used alone or in combination of two or more.

  The amount of filler used is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the epoxy resin A from the viewpoint of good balance between mechanical properties (particularly toughness), heat resistance and solvent resistance. More preferably, it is 1-10 mass parts.

  In the epoxy resin composition for fiber-reinforced composite material of the present invention, the thermoplastic resin C used when producing the adsorbent filler is not limited. For example, the same thing as the thermoplastic resin B is mentioned.

Thermoplastic resin C has a good balance of mechanical properties (particularly toughness), heat resistance, and solvent resistance, and in epoxy resin A, UCST (upper critical solution temperature) or LCST (lower critical solution temperature). Preferably, the polymer has UCST or LCST can be appropriately set according to the type and amount of thermoplastic resin and thermosetting resin.
The thermoplastic resin B and the thermoplastic resin C have the same and similar properties (for example, from the viewpoint of a good balance of mechanical properties (particularly toughness), heat resistance and solvent resistance, and excellent handling workability) , Molecular weight, functional group).

As a combination of the thermoplastic resin C and the filler constituting the adsorption filler, for example, at least one selected from the group consisting of polyethersulfone (polyethersulfone), polyethersulfone having a hydroxy group, and polyetherimide Examples include a combination of a thermoplastic resin and at least one selected from the group consisting of fumed silica, carbon black, and carbon nanotubes.
The adsorbent fillers can be used alone or in combination of two or more.

In the present invention, the adsorption coefficient defined by the following (formula 1) is greater than 0 and 0.8 or less.
(Formula 1)
Adsorption coefficient = Amount of the thermoplastic resin C adsorbed on 100 parts by mass of the filler (mass part) / Specific gravity of the thermoplastic resin C / DBP oil absorption of the filler (mL / 100 g)
= [Amount of the thermoplastic resin C adsorbed on 100 parts by mass of the filler (mass part) / Specific gravity of the thermoplastic resin C] / DBP oil absorption of the filler (mL / 100 g)
In the present invention, the adsorption coefficient defined by (Equation 1) is the ratio of the volume of the thermoplastic resin C adsorbed by the same type and amount of filler to the volume of DBP that can be absorbed by 100 parts by mass of a certain filler. Is the value of
When the adsorption coefficient is 1, the filler means a state in which the entire surface is coated with the thermoplastic resin C.
When the adsorption coefficient is greater than 0 and 0.8 or less, the filler is in a state where a part of the surface thereof is covered with the thermoplastic resin C, and the entire surface of the filler is not covered with the thermoplastic resin C. As a result, a thermosetting resin excellent in toughness and solvent resistance can be obtained.

  The adsorption coefficient is preferably from 0.1 to 0.7, preferably from 0.2 to 0.6, from the viewpoint of good balance between mechanical properties (particularly toughness), heat resistance, and solvent resistance. Is more preferable.

  The amount of the thermoplastic resin C adsorbed on the filler has an adsorption coefficient with respect to 100 parts by mass of the filler from the viewpoint of a good balance of mechanical properties (particularly toughness), heat resistance and solvent resistance, and excellent thixotropy. It is preferably an amount satisfying that it is greater than 0 and 0.8 or less, more preferably an amount satisfying that it is 0.1 to 0.7, and 0.2 to 0.6. Further preferred.

  The amount of the adsorbent filler is preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the epoxy resin A from the viewpoint of good balance between mechanical properties (particularly toughness), heat resistance and solvent resistance. 1 to 20 parts by mass is more preferable.

The adsorbent filler is not particularly limited for its production. For example, thermoplastic resin C having LCST and filler are mixed with thermosetting resin A (epoxy resin A) and thermosetting resin A (epoxy resin A), and thermosetting resin A at a temperature lower than LCST. (Epoxy resin A) and thermoplastic resin C are mixed together, then phase separated from thermosetting resin A (epoxy resin A) at a temperature equal to or higher than LCST, and the separated thermoplastic resin C is adsorbed to the filler. Can be manufactured by.
The combination of the thermoplastic resin C having LCST with respect to the thermosetting resin A (epoxy resin A) and the thermosetting resin A (epoxy resin A) has mechanical properties (particularly toughness), heat resistance, A combination of at least one thermoplastic resin selected from the group consisting of polyethersulfone and polysulfone and a thermosetting resin such as epoxy resin A is preferable from the viewpoint of good balance of solvent properties. LCST in the case of the combination of 10-25 parts by mass of the polyethersulfone of the thermoplastic resin C-1 and 70 parts by mass of the paraaminophenol type trifunctional epoxy resin of the epoxy resin a-1-1 shown in the examples is about 170 ° C. be able to.

The curing agent will be described below.
The hardening | curing agent contained in the epoxy resin composition for fiber reinforced composite materials of this invention will not be restrict | limited especially if it can be used with respect to an epoxy resin. For example, a conventionally well-known thing is mentioned.
Examples of curing agents include 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, imidazole compounds, amine compounds such as tetramethylguanidine; thiourea-added amines; polyamides; polyols; polymercaptans; Carboxylic acid; acid anhydride; carboxylic acid hydrazide; carboxylic acid amide; polyphenol compound; novolac resin; latent curing agent (for example, ketimine, dicyandiamide).
The curing agents can be used alone or in combination of two or more.

  The amount of the curing agent is epoxy resin A (the epoxy resin composition for fiber-reinforced composite material of the present invention is further a solid resin D from the viewpoint of a good balance of mechanical properties (particularly toughness), heat resistance, and solvent resistance. When the epoxy resin d-1 is contained, it is preferably 0.5 to 1.2 equivalents relative to the total amount of the epoxy resin A and the epoxy resin d-1, and 0.6 to 1.1. More preferably, it is equivalent.

The epoxy resin composition for a fiber-reinforced composite material of the present invention can further contain a solid resin D and / or an elastomer that is solid at room temperature, from the viewpoint of superior toughness and solvent resistance.
Solid resin D should just be resin with high affinity with the epoxy resin A at least, either a thermosetting resin or a thermoplastic resin may be used, and both may be used together.

  The molecular weight of the solid resin D is preferably 3,000 to 500,000. When the molecular weight is in the range of 3,000 to 500,000, the solid resin D is prevented from remaining undissolved when the epoxy resin composition for fiber-reinforced composite material of the present invention is cured, and it can be dissolved uniformly. In addition, the toughness of the epoxy resin composition for fiber reinforced composite material can be further improved by uniformly dispersing the solid resin D. In the present invention, the molecular weight is a weight average molecular weight expressed in terms of polystyrene by gel permeation chromatography (GPC).

  Examples of the thermosetting resin as the solid resin D include an epoxy resin d-1, a maleimide resin, a cyanate resin, and a resin having a core-shell structure. Among these, from the viewpoint of excellent mixing workability with the epoxy resin A, the epoxy resin d-1 is more preferable.

The epoxy resin d-1 is not particularly limited as long as it is a compound having two or more epoxy groups. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene skeleton type epoxy resin, and naphthalene skeleton epoxy resin can be used.
Of these, bisphenol A type epoxy resins and bisphenol F type epoxy resins are preferred from the viewpoint of superior toughness and solvent resistance.

  The epoxy resin d-1 is preferably a high molecular weight type from the viewpoint of excellent toughness, and more preferably an epoxy resin having a weight average molecular weight of 3,000 to 20,000. When the weight average molecular weight is in the range of 3,000 to 20,000, it is easy to produce fine particles by an impact pulverization method or the like, and when producing the epoxy resin composition for fiber-reinforced composite material of the present invention, This is preferable because the particles are easily dissolved in the heating and mixing process.

The epoxy equivalent of the epoxy resin d-1 is preferably 1,000 to 5,000 g / eq, more preferably 1,500 to 4,500 g / eq, from the viewpoint of superior toughness and solvent resistance. More preferred.
Further, when the epoxy resin d-1 is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin, the epoxy equivalent of the bisphenol A type epoxy resin or the bisphenol F type epoxy resin is more excellent in toughness and solvent resistance. 1,000 to 5,000 g / eq, more preferably 1,500 to 4,500 g / eq.
When the epoxy equivalent is 1,000 g / eq or more, the toughness is increased, which is preferable. When it is 5,000 g / eq or less, the chemical resistance is good, which is preferable.

Examples of the epoxy resin d-1 include a phenoxy skeleton type epoxy resin having an epoxy group at the molecular end. The phenoxy skeleton type epoxy resin can increase the affinity with the epoxy resin A by having an epoxy group at the molecular end.
The phenoxy skeleton type epoxy resin is superior in toughness, can increase the affinity with the epoxy resin A, and can increase the softening point, and thus consists of a bisphenol A type epoxy resin and a bisphenol F type epoxy resin. What is obtained using at least 1 sort (s) chosen from a group is preferable.

  The weight average molecular weight of the phenoxy skeleton type epoxy resin is preferably 20,000 to 100,000, and more preferably 40,000 to 80,000. When the weight average molecular weight of the phenoxy skeleton type epoxy resin is in such a range, it is easy to produce fine particles by an impact pulverization method or the like. When producing the epoxy resin composition for a fiber-reinforced composite material of the present invention, heat mixing This is because the particles are easily dissolved in the process.

  The epoxy equivalent of the phenoxy skeleton type epoxy resin is preferably 5,000 to 30,000 g / eq, and more preferably 6,000 to 20,000 g / eq. When the epoxy equivalent is set to 5,000 g / eq or more, the epoxy resin A is not completely compatible after heat curing, and it becomes possible to form a dispersed phase separated in the continuous phase of the epoxy resin A after curing. When it is 30,000 g / eq or less, it can be easily dissolved in the epoxy resin A during heating and mixing.

  The thermoplastic resin as the solid resin D is not particularly limited. For example, those having a reactive functional group for forming the epoxy resin A at the molecular terminal are preferable from the viewpoint of superior toughness.

In order that the solid resin D is completely dissolved in the epoxy resin A at the time of heating and mixing, the shape of the solid resin D is preferably a particle size as one of preferred embodiments.
The average particle diameter of the solid resin D is preferably 100 μm or less, and more preferably 5 to 100 μm. When the average particle size of the solid resin D is within such a range, the solid resin D is easily dissolved in the epoxy resin A when the temperature reaches a predetermined temperature in the heating and mixing step. While adjusting the viscosity of a resin composition appropriately, the solid resin D can disperse | distribute in an epoxy resin A phase, and the toughness of hardened | cured material can be improved more.
Solid resin D can be used individually or in combination of 2 or more types, respectively.
The solid resin D is not particularly limited for its production. For example, a conventionally well-known thing is mentioned.

The elastomer is not particularly limited. An example is silicone elastomer.
From the viewpoint of excellent dispersibility, the shape of the elastomer is mentioned as one of preferred embodiments that is a particle size. The average particle size of the elastomer is preferably 100 μm or less, more preferably 0.1 to 100 μm.
The elastomers can be used alone or in combination of two or more. The elastomer is not particularly limited for its production. For example, a conventionally well-known thing is mentioned.
The amount of the solid resin D and / or elastomer (the total when the solid resin D and the elastomer are used in combination) is 1 to 20 with respect to 100 parts by mass of the epoxy resin A from the viewpoint of superior toughness and solvent resistance. It is preferable that it is a mass part, and it is more preferable that it is 3-15 mass parts.

  The epoxy resin composition for fiber-reinforced composite material of the present invention is not limited to the effects of the composition of the present invention in addition to the epoxy resin A, thermoplastic resin B, adsorption filler, curing agent, solid resin D, and elastomer. Additives can be included. Examples of the additive include a curing catalyst such as boron trifluoride / amine salt catalyst, a filler, an anti-aging agent, a solvent, a flame retardant, a reaction retarding agent, an antioxidant, a pigment (dye), a plasticizer, a rocking agent. Modification modifiers, ultraviolet absorbers, surfactants (including leveling agents), dispersants, dehydrating agents, adhesion imparting agents, and antistatic agents are exemplified.

The manufacturing method of the epoxy resin composition for fiber reinforced composite materials of this invention is demonstrated below.
The adsorbent filler may be applied in a state where a thermoplastic resin C (tough resin) is previously attached to the filler, or the thermoplastic resin C is placed around the filler by resin phase separation during blending or curing. You may use the method to make it adsorb | suck.

For example, a solution in which the epoxy resin A, the thermoplastic resin C, and the filler are phase-separated from the epoxy resin A at a temperature below the UCST or a temperature above the LCST at a temperature above the UCST or below the LCST. A resin mixing step to form a mixed solution in a one-phase region at a temperature;
The resin mixed solution is set to a temperature equal to or lower than the UCST or a temperature equal to or higher than the LCST, the thermoplastic resin C is phase-separated from the epoxy resin A, the resin mixed solution becomes a two-phase region, and the phase-separated thermoplastic resin C is An adsorption step in which an adsorption filler-containing mixture containing an adsorption filler is obtained by adsorbing to the filler,
A thermoplastic resin B addition step of adding the thermoplastic resin B to the adsorbent filler-containing mixture;
The manufacturing method which has the hardening | curing agent mixing process of mixing the adsorption filler mixture and hardening | curing agent after the thermoplastic resin B addition process is mentioned.
In the present invention, the epoxy resin resin A and the thermoplastic resin C are mixed to form a uniform solution, and then the temperature is raised. The temperature at which fogging is observed in the system is defined as LCST.
After the epoxy resin A and the thermoplastic resin C are mixed to form a uniform solution, the temperature is lowered, and the temperature at which clouding begins to be observed in the system is defined as UCST.
When the composition of the present invention further contains a solid resin D and / or an elastomer, the solid resin D and / or the elastomer can be added into the system in the thermoplastic resin B addition step. When a part of the epoxy resin A is used in the resin mixing step, the room temperature solid component can be added to the remaining epoxy resin A in the system in the thermoplastic resin B addition step.

The resin mixing step will be described below.
In the resin mixing step, a solution containing epoxy resin A, thermoplastic resin C, and filler and phase-separating from the epoxy resin A at a temperature equal to or lower than UCST or a temperature equal to or higher than LCST is used to convert UCST. This is a step of preparing a mixed solution in a one-phase region at a temperature exceeding or below LCST.

Epoxy resin A, thermoplastic resin C, and filler are as defined above.
The amount of filler used in the resin mixing step is 0.1 to 100 mass with respect to 100 mass parts of epoxy resin A from the viewpoint of good balance between mechanical properties (particularly toughness), heat resistance, and solvent resistance. Parts, preferably 1 to 10 parts by mass.
The amount of the thermoplastic resin C used in the resin mixing step is (Formula 1) with respect to 100 parts by mass of the filler from the viewpoint of good balance between mechanical properties (particularly toughness), heat resistance, and solvent resistance. The amount of the defined adsorption coefficient is preferably greater than 0 and satisfying 0.8 or less, more preferably from 0.1 to 0.7, and even more preferably from 0.2 to 0.6.

The mixed solution obtained in the resin mixing step contains an epoxy resin A, a thermoplastic resin C, and a filler, and the epoxy resin A and the thermoplastic resin C are in a one-phase region.
The one-phase region refers to a state where the epoxy resin A and the thermoplastic resin C are compatible.
In the resin mixing step, the epoxy resin A, the thermoplastic resin C, and the filler are stirred at a temperature higher than UCST or lower than LCST, for example, for 0.5 to 1.5 hours to obtain a mixed solution. be able to.

The adsorption process will be described below.
In the adsorption step, the temperature of the resin mixed solution is set to a temperature of UCST or lower or a temperature of LCST or higher, the thermoplastic resin C is phase-separated from the epoxy resin A, the resin mixed solution becomes a two-phase region, and the phase-separated thermoplastic resin C is This is a process of adsorbing to a filler to become an adsorbent filler.

  The two-phase region refers to a state in which the epoxy resin A is a main component and the thermoplastic resin C is a main component. The adsorbent filler mixture obtained in the adsorption step contains at least the epoxy resin A and the adsorbent filler. In the adsorption step, the mixed solution can be stirred, for example, for 1 to 10 hours under conditions of a temperature below UCST or a temperature above LCST.

The thermoplastic resin B addition step will be described below.
The thermoplastic resin B addition step is a step of adding the thermoplastic resin B to the adsorbent filler-containing mixture obtained in the adsorption step. The thermoplastic resin B used has the same meaning as described above. The temperature in the thermoplastic resin B addition step is not particularly limited. For example, 70-120 degreeC is mentioned.

The curing agent mixing step will be described below.
The curing agent mixing step is a step of mixing the adsorbent filler mixture and the curing agent after the thermoplastic resin B addition step. In the curing agent mixing step, the temperature at which the adsorbent filler mixture and the curing agent are mixed is preferably as low as possible from the viewpoint of suppressing the curing reaction. The method for mixing the adsorbent filler mixture and the curing agent is not particularly limited. In the curing agent mixing step, the thermosetting resin composition can be obtained by adjusting the adsorbent filler mixture to the above temperature, adding the curing agent thereto, and stirring for 0.25 to 0.5 hours, for example. .

  The epoxy resin composition for fiber-reinforced composite materials of the present invention can be cured by heat. The temperature for curing the epoxy resin composition for fiber-reinforced composite material of the present invention is 160 to 200 ° C. from the viewpoint of good balance between mechanical properties (particularly toughness), heat resistance and solvent resistance. Is preferred.

In the epoxy resin composition for fiber-reinforced composite material of the present invention, at least the epoxy resin A forms a continuous phase and the adsorbent filler can be dispersed in at least the continuous phase of the epoxy resin A in the form after curing. The epoxy resin A and the thermoplastic resin B may form a co-continuous phase.
Since the adsorbent filler forms a fine dispersed phase in at least the continuous phase of the epoxy resin A, the toughness can be improved by dispersing the stress concentration inside the epoxy resin A phase as a whole. By improving the toughness of the composition, the strength of the fillet is increased, and the self-adhesive strength of the prepreg can be improved. In addition, the adsorption filler should just be disperse | distributed in the continuous phase of the epoxy resin A, and may be disperse | distributed to the continuous phase of the thermoplastic resin B. FIG.
A form in which only the thermoplastic resin B does not form a continuous phase (that is, the morphology does not have an inverted sea-island structure) is preferable from the viewpoint of excellent solvent resistance.

When the epoxy resin composition for fiber-reinforced composite material of the present invention contains the solid resin D and / or elastomer, after curing the composition, at least the epoxy resin A is in the form (morphology) of the cured product obtained. A continuous phase is formed and the adsorbent filler and the solid resin D and / or elastomer can be dispersed in at least the continuous phase of the epoxy resin A. The epoxy resin A and the thermoplastic resin B may form a co-continuous phase.
At least in the continuous phase of the epoxy resin A, the solid resin D and / or the elastomer forms a fine dispersed phase, so that the internal stress concentration of the epoxy resin A phase is dispersed throughout and the toughness is further improved. can do. By further improving the toughness of the composition, the strength of the fillet can be improved and the self-adhesive strength of the prepreg can be improved. The solid resin D and / or the elastomer need only be dispersed in at least the continuous phase of the epoxy resin A, and may be dispersed in the continuous phase of the thermoplastic resin B.

  In the cured product obtained after curing the composition, the average particle size of the solid resin D or the elastomer as the domain is preferably 0.05 to 2 μm from the viewpoint of better toughness and solvent resistance. 1 to 0.5 μm is more preferable.

Using the cured product obtained after curing the epoxy resin composition for fiber-reinforced composite material of the present invention, the fracture toughness value measured according to ASTM D5045-99 is higher toughness, peel strength [for example From the viewpoint that the peel strength after self-adhesion between the face plate such as a prepreg and other members (for example, honeycomb core) can be increased, 1.8 MPa · m ^1/2 or more is preferable. 0 MPa · m ^1/2 or more is more preferable.

In the epoxy resin composition for fiber-reinforced composite material of the present invention, the minimum viscosity by dynamic viscoelasticity measurement at a temperature rising rate of 2 ° C./min is preferably 1 to 100 Pa · s, and preferably 5 to 40 Pa · s. Is more preferable. When making the minimum viscosity of a dynamic viscoelasticity measurement into said range, it is preferable when expressing the productivity and self-adhesiveness of a prepreg. In the case of 1 Pa · s or more, a good fillet can be formed, and self-adhesiveness is improved. In the case of 100 Pa · s or less, the reinforcing fiber can be easily impregnated with the resin composition at the time of prepreg production while maintaining the fillet formability.
In the present invention, the minimum viscosity by dynamic viscoelasticity measurement is a temperature rise rate of 2 ° C./min between 25 ° C. and 200 ° C. using the epoxy resin composition for fiber reinforced composite material of the present invention as a sample. , And the minimum value of the complex viscosity in the dynamic viscoelasticity measurement at a frequency of 10 rad / sec and a strain of 1%.

The epoxy resin composition for fiber-reinforced composite material according to the present invention is a resin used for prepreg production having a viscosity at 50 ° C. of 5,000 Pa · s or less as measured by dynamic viscoelasticity at a temperature rising rate of 2 ° C./min. This is preferable from the viewpoint of excellent film coating workability.
In the present invention, the viscosity at 50 ° C. by dynamic viscoelasticity measurement is a temperature rising rate of 2 from a temperature of 25 ° C. to 200 ° C. using the epoxy resin composition for fiber-reinforced composite material of the present invention as a sample. It shall mean the value at 50 ° C. of the complex viscosity in dynamic viscoelasticity measurement at a temperature of 10 ° C./min, a frequency of 10 rad / sec, and a strain of 1%.

The cured product of the epoxy resin composition for fiber-reinforced composite material of the present invention is excellent in solvent resistance. Examples of the solvent include methyl ethyl ketone and acetone.
One preferable embodiment is that the cured product obtained from the epoxy resin composition for fiber-reinforced composite material of the present invention is free from cracks after being immersed in a solvent (for example, methyl ethyl ketone) at room temperature.

Examples of the use of the epoxy resin composition for fiber-reinforced composite materials of the present invention include prepreg matrix resins, adhesives, primers, sealing materials, casting materials, sealants, paints, and the like.
The adherend to which the epoxy resin composition for fiber-reinforced composite material of the present invention can be used is not particularly limited. Examples thereof include carbon fiber, glass fiber, reinforcing fiber such as aramid fiber, plastic, rubber, glass, ceramic, concrete, mortar, aluminum alloy, titanium alloy, stainless alloy, and steel.

  Since the epoxy resin composition for fiber-reinforced composite material of the present invention can be a cured product having excellent toughness and solvent resistance, the epoxy resin composition for fiber-reinforced composite material of the present invention is used as a matrix resin and combined with reinforcing fibers. In this case, a prepreg excellent in toughness and solvent resistance can be produced. Moreover, by using the epoxy resin composition for fiber-reinforced composite material of the present invention, it is easy to form an appropriate fillet and a prepreg having high self-adhesiveness can be produced.

Next, the prepreg of the present invention will be described below.
The prepreg of the present invention is obtained by combining the epoxy resin composition for fiber-reinforced composite material of the present invention and reinforcing fibers.

  Specifically, the prepreg of the present invention is obtained by impregnating reinforcing fibers with an epoxy resin composition for fiber-reinforced composite materials. The matrix composition used in the prepreg of the present invention is not particularly limited as long as it is an epoxy resin composition for fiber-reinforced composite materials of the present invention.

The reinforcing fiber used in the prepreg of the present invention is not particularly limited, and examples thereof include conventionally known fibers. Especially, it is preferable that it is at least 1 sort (s) chosen from the group which consists of carbon fiber, glass fiber, and an aramid fiber from a viewpoint of intensity | strength, and it is more preferable that it is carbon fiber.
Examples of aramid fibers include Kevlar.
The fiber is not particularly limited in its form, and examples thereof include roving, nonwoven fabric, knitted fabric, and tulle. The optimum value of the basis weight of the fiber varies depending on the form and use, but for example, in the case of a carbon fiber fabric, it is preferably 150 to 400 g / m ² .
Examples of commercially available fibers include carbon fiber T-300 manufactured by Toray Industries, Inc. and carbon fiber HTA manufactured by Toho Rayon.

  The production method of the prepreg of the present invention is not particularly limited. Examples thereof include a wet method using a solvent and a hot melt method which is a solventless method. It is preferable that the usage-amount of a solvent is 80-200 mass parts with respect to 100 mass parts of solid content of the epoxy resin composition for fiber reinforced composite materials from a viewpoint that drying time can be shortened.

  In the prepreg of the present invention, the content of the matrix resin is preferably 30 to 60% by mass in the prepreg from the viewpoint of a good balance of mechanical properties (particularly toughness), heat resistance and solvent resistance. .

  The method of using the prepreg of the present invention is not particularly limited, and examples thereof include a method of curing the prepreg of the present invention as it is and a method of semi-curing and further curing the prepreg of the present invention. The conditions for curing are the same as described above.

  The use of the prepreg of the present invention is not particularly limited. By curing the prepreg of the present invention, for example, a conventionally known fiber reinforced composite material can be obtained. Specifically, for example, aircraft parts such as fairings, flaps, leading edges, floor panels, propellers, fuselage; motorcycle parts such as motorcycle frames, cowls, fenders; doors, bonnets, tailgates, side fenders, side panels, Auto parts such as fender, energy absorbing member, trunk lid, hard top, side mirror cover, spoiler, diffuser, ski carrier, engine cylinder cover, engine hood, chassis, air spoiler, propeller shaft; leading vehicle nose, roof, side panel, Vehicle outer panels such as doors, bogie covers, side skirts; railway vehicle parts such as luggage racks and seats; interior, wing inner panels, outer panels, roofs, floors, etc. Aero parts such as side skirts to be mounted on moving vehicles and single vehicles; Cases for notebook PCs, mobile phones, etc .; Medical uses such as X-ray cassettes and top plates; Applications for acoustic products such as flat speaker panels and speaker cones; Golf heads, Sports plate applications such as faceplates, snowboards, surfboards, protectors, etc .; general industrial applications such as leaf springs, windmill blades, elevators (籠 panels, doors).

Further, a fiber reinforced composite material can be produced by laminating the prepreg of the present invention and another member (for example, a honeycomb core). Examples of the fiber reinforced composite material that can be produced by laminating the prepreg of the present invention and other members include a honeycomb sandwich panel.
The prepreg of the present invention can form a fillet having excellent toughness and solvent resistance, high self-adhesive strength, and excellent strength by using the epoxy resin composition for fiber-reinforced composite material of the present invention. Excellent tackiness, drape, productivity, and workability.
Further, the fiber reinforced composite material obtained from the prepreg of the present invention is excellent in toughness and solvent resistance, can be bonded to other members without using an adhesive, has excellent prepreg smoothness, and has a porosity (surface Have excellent appearance and surface properties.

Next, the honeycomb sandwich panel of the present invention will be described below.
The honeycomb sandwich panel of the present invention is obtained by laminating and curing the prepreg of the present invention and a honeycomb core.

  The prepreg used in the honeycomb sandwich panel of the present invention is not particularly limited as long as it is the prepreg of the present invention. Since the prepreg used in the honeycomb sandwich panel of the present invention has excellent adhesiveness, it can be bonded to the honeycomb core without using an adhesive, and a fillet having high strength can be formed.

Further, the honeycomb core used in the honeycomb sandwich panel of the present invention is not particularly limited. Examples thereof include at least one selected from the group consisting of an aramid honeycomb, an aluminum honeycomb, a paper honeycomb, and a glass honeycomb.
The size of the hexagonal column of the honeycomb core honeycomb structure is not particularly limited, and the honeycomb core preferably has a cell size length of 1/8 to 3/8 inch from the viewpoint of strength and weight reduction.

The honeycomb sandwich panel of the present invention is not particularly limited for its production.
An example of a method for manufacturing a honeycomb sandwich panel of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a perspective view schematically showing an example of the honeycomb sandwich panel of the present invention.
FIG. 2 is a cross-sectional view schematically showing an example of a cross section obtained by cutting the honeycomb sandwich panel in parallel with the side surfaces of the prisms of the honeycomb core. Part a of FIG. 2 is a honeycomb sandwich panel to which a prepreg formed from a conventional resin composition for a prepreg sheet is bonded. Part b of FIG. 2 is an example of the honeycomb sandwich panel of the present invention.

  In FIG. 1, the honeycomb sandwich panel 1 is obtained by bonding a prepreg 10 and a honeycomb core 11. More specifically, in the honeycomb sandwich panel 1, a prepreg 10 formed of the composition of the present invention is bonded to one or both ends (both not shown) of the honeycomb core 11 having a honeycomb structure. It can be produced by heat-curing with an autoclave or the like while pressing from both ends.

In FIG. 2, when using a prepreg in which the conventional composition is used as an epoxy resin composition for a fiber reinforced composite material, as shown in part a of FIG. Even if it press-fits, the epoxy resin composition for fiber-reinforced composite materials all falls on the lower surface portion 13 ′ and no fillet is formed on the upper surface portion (not shown), or the prepreg 10 and the honeycomb core 11 are partially formed. There may be a case where a gap 13 is formed on the bonding surface.
In contrast, when the composition of the present invention is used, as shown in part b of FIG. 2, the prepreg 10 and the honeycomb core 11 are completely bonded to each other, and the epoxy resin composition for fiber-reinforced composite material is formed from the prepreg. An appropriate amount of the composition can be present in the prepreg without causing the resin component to disappear from the prepreg due to excessive outflow.
Accordingly, the upper fillet 14 can complete curing while maintaining an appropriate shape. Also, the lower fillet 14 ′ is formed by the surface tension when the viscosity once decreases on the lower surface, and the epoxy resin composition for fiber-reinforced composite material is appropriately held to complete the curing.

  The heating temperature at the time of bonding the prepreg 10 and the honeycomb core 11 is preferably 160 to 200 ° C, more preferably 170 to 190 ° C, from the viewpoint of heat resistance of the cured product.

The curing conditions for bonding the prepreg 10 and the honeycomb core 11 are 2 to 5 ° C./min, pressurization is 2.5 to 4.0 kg / cm ² , and the temperature is increased to 150 to 185 ° C. One preferred embodiment is a method in which the temperature is maintained at 185 ° C. for 1 to 2 hours and then lowered to room temperature at 2 to 5 ° C./min.
By such a method, the honeycomb sandwich panel of the present invention can be manufactured.

The honeycomb sandwich panel of the present invention is excellent in fillet formability, fillet strength, mechanical strength, and workability.
The honeycomb sandwich panel of the present invention can be used as a structural material for aircraft and automobiles, for example.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
<Evaluation>
About each composition obtained as follows, resin viscosity, cured resin toughness (K _1C ), honeycomb panel peel strength, solvent resistance, thixotropy, and LCST were evaluated by the following methods. The results are shown in Table 1.

1. Adsorption coefficient 20 g of the adsorbent filler-containing mixture (intermediate product) obtained as described below was subjected to a separation operation at 19,000 (rpm) for 1 hour by a centrifugal separator to obtain a precipitate. Next, the thermosetting component contained in the separated sediment was washed and removed with methyl ethyl ketone (MEK) to extract the adsorbent filler. The amounts of adsorbed filler extracted from 20 g of the adsorbent filler-containing mixture are shown in Tables 1 and 2.
The extracted adsorption filler was analyzed by a thermogravimetric analyzer (TGA), and the mass (W _TP ) and the mass (W _F ) of the thermoplastic resin component C in the adsorption filler were determined. Tables 1 and 2 show the mass (W _TP ) of the thermoplastic resin component C and the mass (W _F ) of the filler in the obtained adsorption filler. Moreover, the adsorption coefficient of the adsorption filler in an Example was computed by the following (Formula 2). The adsorption coefficients of the adsorbent fillers in the examples are shown in Tables 1 and 2.
In formula 2, W _TP : mass of the thermoplastic resin C in the adsorption filler (g), Ca _TP : specific gravity of the thermoplastic resin C, W _F : mass of the filler in the adsorption filler (g), DBP: DBP of the filler Oil absorption (mL / 100 g).

2. Resin viscosity Using the epoxy resin composition for fiber-reinforced composite material obtained as described below as a sample, a temperature rising rate of 2 ° C./min, a frequency of 10 rad / sec, a strain of 1 between a temperature of 25 ° C. and 200 ° C. The minimum value of the complex viscosity in the dynamic viscoelasticity measurement under the condition of% and the viscosity at 50 ° C. were measured.

3. Cured resin toughness (K _1C )
A resin plate having a thickness of 7 mm was formed on the release paper with each composition obtained as described below, and this was put in an autoclave and heated from 70 ° C. to 180 ° C. at a heating rate of 2 ° C./min. It was cured at 0.32 MPa and 180 ° C. for 2 hours to produce a cured product having a thickness of 7 mm.
Fracture toughness values (stress intensity factors, units: MPa · m ^1/2 ) were measured from the obtained cured product in accordance with ASTM D-5045-99 under conditions of room temperature (25 ° C.). The obtained fracture toughness value is shown as cured resin toughness.

4). Honeycomb panel peel strength Created using the composition obtained as described below and carbon fibers woven in a plain weave as reinforcing fibers (T300-3000, weight per unit area 198 g / m ² ). Two prepregs were laminated and placed on both sides of a honeycomb core (Nomex Honeycomb SAH-1 / 8-8.0 manufactured by Showa Aircraft Industry Co., Ltd.), then placed in a bag, which was placed in an autoclave at a temperature of 180 ° C., The honeycomb panel was manufactured by heating for 2 hours (heating rate of 2.8 ° C./min) and curing. During this time, the inside of the autoclave was pressurized to 0.32 MPa with compressed air.

  In accordance with ASTM D1781, the obtained honeycomb panel is arranged on the upper side of the honeycomb core (Bag side: the surface in contact with the vacuum bag) and the lower side (Tool side: the surface in contact with the forming jig) in accordance with ASTM D1781. Each of the face plates thus processed was processed into a predetermined size, and the peel strength (lb-in / 3 in) of the test piece at a temperature of 23 ° C. (dry state) was measured.

5. Solvent resistance A laminate of two prepregs similar to those used in the honeycomb peel strength test was placed in an autoclave and heated from 70 ° C. to 180 ° C. at a heating rate of 2 ° C./min, pressure 0.32 MPa, 180 Curing was carried out at 0 ° C. for 2 hours to produce a cured laminate having a thickness × width × length of 0.5 mm × 25 mm × 50 mm. It was immersed in methyl ethyl ketone for 90 minutes at 25 ° C. and lifted from the solvent, and the surface state of the cured product was observed with an optical microscope.
The case where there was no change from before immersion was evaluated as “Good”, the case where slight surface cracks were observed was “△”, and the case where remarkable surface cracks were observed was evaluated as “X”.

6). LCST Measurement Method After mixing the epoxy resin a-1-1 and the thermoplastic resin C-1 in parts by mass shown in Table 1 with stirring at 120 ° C. for 1 hour, the conditions at 80 ° C. The solution was degassed under reduced pressure to obtain a clear solution. The temperature was raised stepwise in increments of 5 ° C., and the temperature at which clouding began to be observed in the system was defined as LCST.

<Production of composition>
Using the components shown in Table 1 in the amounts shown in the same table (unit: parts by mass), a composition was produced by the following method.
1. Compounding treatment First, epoxy resin a-1-1, filler and thermoplastic resin C were put in a container, and these were stirred for 1 hour under the condition of 120 ° C., followed by mixing treatment, followed by the condition of 180 ° C. The mixture was stirred for 1 hour and subjected to a composite treatment (resin mixing step and adsorption step) to obtain an adsorbent filler-containing mixture (intermediate product). Furthermore, it returns to 120 degreeC conditions, adds epoxy resin a-2-1, epoxy resin a-1-2, thermoplastic resin B, epoxy resin d-1-1, epoxy resin d-1-2, and stirs and mixes for 1 hour. Thus, an adsorbent filler-containing mixture was obtained.
After lowering the temperature of the adsorbent filler-containing mixture to 70 ° C. or less, the adsorbent filler-containing mixture was mixed with a curing agent and stirred to obtain an epoxy resin composition for fiber-reinforced composite material (curing agent mixing step).
In Comparative Example 1, the epoxy resin a-1-1 and the filler 1 were stirred and mixed for 1 hour under the condition of 180 ° C., and the same operation as the composite treatment was performed. 20 g was taken from the resulting mixture and centrifuged as in the above evaluation of the adsorption coefficient.

2. When composite treatment is not performed: Put epoxy resin A, filler and thermoplastic resin B in a container, stir them for 1 hour at 120 ° C., mix the mixture, cool the mixture to 70 ° C. or less, and then harden the mixture. Was added to obtain a composition.

Details of each component shown in Table 1 are as shown in Table 2 below.
In addition, the DBP oil absorption of the filler 1 is 350 mL / 100 g, and the shape is amorphous.

As is apparent from the results shown in Table 1, Comparative Examples 1 to 3 containing no adsorbent filler were poor in solvent resistance and low in toughness. In Comparative Example 1, since no thermoplastic resin is used during the composite treatment, the adsorbent filler does not exist even if the same operation as the composite treatment is performed.
On the other hand, Examples 1-3 are excellent in toughness and solvent resistance.
In Examples 1 to 3, the form after curing was such that at least the epoxy resin A formed a continuous phase, and the adsorbent filler was dispersed in at least the continuous phase.

As described above, by containing the adsorbent filler, it was possible to develop toughness corresponding to 40 to 50 parts by mass of the thermoplastic resin B added with respect to 100 parts by mass of the epoxy resin A according to the conventional method.
In the resin compounded with a high addition amount of the thermoplastic resin B, the thermoplastic resin forms a continuous phase after curing, and this portion is easily deteriorated when immersed in a solvent. However, in the epoxy resin composition for fiber-reinforced composite material of the present invention, Since the thermoplastic resin does not easily form a continuous phase, the resistance to the solvent is high.
The epoxy resin composition for fiber-reinforced composite material according to the present invention has low viscosity in a work area (for example, 100 ° C. or less), and not only workability during prepreg production but also workability after prepreg formation ( Tuck, drape) is also superior to the high-addition compounding system of thermoplastic resin. Further, molding defects (voids) at the time of curing hardly occur.
By utilizing the effect of the adsorption filler, it is not necessary to maintain the minimum viscosity of the resin higher than necessary, and matrix mixing at a level that does not sacrifice workability is possible.

DESCRIPTION OF SYMBOLS 1 Honeycomb sandwich panel 10 Fiber reinforced prepreg 11 Honeycomb core 12 End part 13 Crevice 13 'Lower surface part 14 Upper fillet 14' Lower fillet a Conventional honeycomb sandwich panel b Honeycomb sandwich panel of this invention c Cell size

Claims (17)

Containing an epoxy resin A, a thermoplastic resin B, an adsorption filler in which the thermoplastic resin C is adsorbed on the filler, and a curing agent;
The epoxy resin A includes an epoxy resin a-1 having a viscosity at 25 ° C. of 100 to 2,000 mPa · s,
The thermoplastic resin C has a weight average molecular weight of 20,000 to 100,000,
The filler is at least one selected from the group consisting of carbon black and silica;
The adsorbent filler is manufactured by mixing the epoxy resin a-1, the thermoplastic resin C, and the filler,
Satisfying that the adsorption coefficient defined by the following (formula 1) is greater than 0 and 0.8 or less,
The epoxy resin composition for fiber-reinforced composite materials in which at least the epoxy resin A forms a continuous phase and the adsorbent filler is dispersed in at least the continuous phase.
(Formula 1)
Adsorption coefficient = Amount of the thermoplastic resin C adsorbed on 100 parts by mass of the filler (mass part) / Specific gravity of the thermoplastic resin C / DBP oil absorption of the filler (mL / 100 g) The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the shape of the filler is at least one selected from the group consisting of spherical, granular and irregular shapes. The epoxy resin composition for a fiber-reinforced composite material according to claim 1 or 2 , wherein the thermoplastic resin B or the thermoplastic resin C is at least one selected from the group consisting of polyethersulfone and polyetherimide. The epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 3 , wherein an amount of the adsorbent filler is 0.1 to 100 parts by mass with respect to 100 parts by mass of the epoxy resin A. The epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 4 , wherein the thermoplastic resin B or the thermoplastic resin C has a functional group that reacts with the epoxy resin A. The said DBP oil absorption is 10-1,000 mL / 100g, The epoxy resin composition for fiber reinforced composite materials in any one of Claims 1-5 . Furthermore, the epoxy resin composition for fiber-reinforced composite materials according to any one of claims 1 to 6 , comprising a solid resin D and / or an elastomer which is solid at normal temperature. The epoxy resin composition for fiber-reinforced composite material according to claim 7 , wherein the solid resin D is at least one selected from the group consisting of an epoxy resin d-1, a maleimide resin, a cyanate resin, and a resin having a core-shell structure. The fiber according to claim 8 , wherein the epoxy resin d-1 is at least one selected from the group consisting of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a phenoxy skeleton type epoxy resin having an epoxy group at a molecular end. Epoxy resin composition for reinforced composite materials. The epoxy resin composition for fiber-reinforced composite materials according to any one of claims 1 to 9 , wherein the minimum viscosity by dynamic viscoelasticity measurement at a temperature rising rate of 2 ° C / min is 1 to 100 Pa · s. The epoxy resin composition for fiber-reinforced composite materials according to any one of claims 1 to 10 , wherein the viscosity at 50 ° C by dynamic viscoelasticity measurement at a rate of temperature rise of 2 ° C / min is 5000 Pa · s or less. The fracture toughness value measured according to ASTM D5045 using the obtained cured product after curing of the epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 12, is 1.8 MPa. The epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 11 , which is √m or more. A prepreg obtained by combining the epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 12 and a reinforcing fiber. The prepreg according to claim 13 , wherein the content of the epoxy resin composition for fiber-reinforced composite material is 30 to 60% by mass in the prepreg. The prepreg according to claim 13 or 14 , wherein the reinforcing fibers are carbon fibers. A honeycomb sandwich panel obtained by laminating and curing the prepreg according to any one of claims 13 to 15 and a honeycomb core. The honeycomb sandwich panel according to claim 16 , wherein the honeycomb core is at least one selected from the group consisting of an aramid honeycomb, an aluminum honeycomb, a paper honeycomb, and a glass honeycomb.