JP6657605B2 - Epoxy resin composition, molded product, prepreg, fiber reinforced composite material and structure - Google Patents

Description

  The present invention relates to an epoxy resin composition, a molded product, a prepreg, a fiber-reinforced composite material, and a structure. In particular, the present invention relates to an epoxy resin composition for obtaining a fiber-reinforced composite material suitable for use in aircraft materials as well as general industrial applications, and an application thereof.

  BACKGROUND ART A fiber reinforced composite material (FRP) in which a resin and a reinforcing fiber are combined is used for various applications because of its excellent light weight, rigidity, impact resistance, and the like. In particular, carbon fiber reinforced composite materials are lightweight, have high strength, and have high rigidity, and are therefore used in a wide range of fields such as sports and leisure applications such as fishing rods and golf shafts, automobile applications and aircraft applications. In recent years, in addition to the mechanical properties of carbon fiber reinforced composite materials, it has been used as a housing for electronic and electric devices such as notebook computers, taking advantage of the characteristics of carbon fibers such as electromagnetic wave shielding.

Fiber-reinforced composite materials may be required to have flame retardant performance in various applications. For example, when a fiber-reinforced composite material is used for an electronic / electric device or a structure for an aircraft, the fire due to heat generation may cause a fire.
As a method of making a fiber-reinforced composite material flame-retardant, a method of adding a brominated epoxy resin to a matrix resin composition has been widely used. However, in recent years, in consideration of the burden on the human body and the environment of substances generated when a resin composition containing halogen is burned, as an alternative to the addition of brominated epoxy resin, an epoxy resin composition containing a phosphorus-based flame retardant has been proposed. Things have come to be used. In such an epoxy resin composition, for example, dicyandiamide and imidazole may be used in combination as a curing agent (see Patent Document 1).

JP 2012-241179 A

  However, the resin composition of Patent Literature 1 has a problem that a high temperature and a long time are required for curing. Further, the fiber-reinforced composite material obtained by using the resin composition of Patent Document 1 does not always satisfy all of the flame retardancy and the heat resistance.

  The present invention has been made in view of the above circumstances, and it is possible to obtain a fiber-reinforced composite material having excellent flame retardancy and heat resistance, and to use an epoxy resin composition having excellent curability, a molded product, a prepreg, and the prepreg. It is an object to provide a fiber-reinforced composite material and a structure obtained by the above method.

  The present inventors have conducted intensive studies and found that, in an epoxy resin composition containing a phosphorus compound as a flame retardant, a dicyandiamide or a derivative thereof as a curing agent, and a compound having a dimethylureido group and a specific imidazole as a curing accelerator are used in combination. As a result, the present inventors have found that an epoxy resin composition having a high curing rate can be obtained, and have completed the present invention.

That is, the present invention has the following aspects.
[1] An epoxy resin composition containing the following components (A), (B), (C), (D) and (E).
(A) component: phosphorus compound (B) component: epoxy resin (C) component: dicyandiamide or a derivative thereof (D) component: curing accelerator having a dimethylureido group (E) component: imidazole adduct, clathrate imidazole, microcapsule At least one curing accelerator selected from the group consisting of a type imidazole and an imidazole compound coordinated with a stabilizer [2] wherein the component (D) is phenyldimethylurea, methylenebis (phenyldimethylurea), tolylenebis (dimethyl) The epoxy resin composition according to [1], which is at least one compound selected from the group consisting of urea).
[3] 1 to 15 parts by mass of the component (C), 1 to 30 parts by mass of the component (D), and 1 to 30 parts by mass of the component (E) based on 100 parts by mass of the component (B). The epoxy resin composition according to [1] or [2].
[4] In the epoxy resin composition 100% by mass (however, when the epoxy resin composition contains a metal hydroxide, the component (A) in the epoxy resin composition 100% by mass excluding the metal hydroxide) [1] The epoxy resin composition according to any one of [1] to [3], wherein the epoxy resin composition contains an amount of a phosphorus atom content of 0.3 to 5.0% by mass.
[5] The component (A) is at least one phosphorus compound selected from the group consisting of a phosphorus-containing epoxy resin, red phosphorus, a phosphazene compound, a polyphosphonate, a phosphate, and a phosphate ester. The epoxy resin composition according to any one of [4].
[6] The epoxy resin composition according to any one of [1] to [5], further comprising the following component (F).
(F) component: thermoplastic resin [7] The epoxy resin composition according to [6], wherein the component (F) is at least one of a phenoxy resin and a polyvinyl formal resin.
[8] The epoxy resin composition according to any one of [1] to [7], further comprising the following component (G).
Component (G): metal hydroxide

[9] A molded article obtained by molding the epoxy resin composition according to any one of [1] to [8].
[10] A prepreg obtained by impregnating a reinforcing fiber aggregate with the epoxy resin composition according to any one of [1] to [8].
[11] A fiber-reinforced composite material obtained by curing the prepreg according to [10].
[12] A structure partially or wholly composed of the fiber-reinforced composite material according to [11].

  According to the present invention, a fiber-reinforced composite material having excellent flame retardancy and heat resistance can be obtained, and an epoxy resin composition having excellent curability, a molded product, a prepreg, and a fiber-reinforced composite material obtained using the prepreg can be obtained. And structures can be provided.

It is a graph which shows an example of the heat flow curve of hardening exotherm at a fixed temperature.

Hereinafter, the present invention will be described in detail.
In the present invention, "epoxy resin" means a compound having two or more epoxy groups in one molecule.
Also, the term "epoxy resin composition" means a composition comprising an epoxy resin, a curing agent, a curing accelerator, and optionally other additives.
In the present invention, the average particle size means a particle size corresponding to 50% of a volume-based cumulative distribution measured by a laser diffraction type particle size distribution measuring method.
In the present invention, a cured product obtained by curing the epoxy resin composition is referred to as a “resin cured product”, and among others, a plate-shaped cured product is sometimes referred to as a “resin plate”.

"Epoxy resin composition"
The epoxy resin composition of the present invention contains the following components (A), (B), (C), (D) and (E). Further, the epoxy resin composition preferably contains the following components (F) and (G).
(A) component: phosphorus compound (B) component: epoxy resin (C) component: dicyandiamide or a derivative thereof (D) component: a curing accelerator having a dimethylureido group (E) component: imidazole adduct, clathrate imidazole, microcapsule At least one type of curing accelerator selected from the group consisting of imidazole compounds and imidazole compounds coordinated with a stabilizer (F) component: thermoplastic resin (G) component: metal hydroxide

<(A) component>
The component (A) is a phosphorus compound.
The phosphorus compound is not particularly limited, and examples thereof include a phosphorus-containing epoxy resin, red phosphorus, a phosphazene compound, a polyphosphonate, a phosphate, and a phosphate. Among these, a phosphorus-containing epoxy resin is preferable because bleed-out hardly occurs due to pressure or heat during processing of the epoxy resin composition or a prepreg containing the same.
These may be used alone or in combination of two or more.

As the component (A), a commercially available product may be used, or a component synthesized by a known production method may be used.
Commercially available phosphorus-containing epoxy resins include, for example, FX-289FA, FX-289-Z1 (all manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.); XEN-0230 and XEN-0140 (all manufactured by SHIN-A). However, the present invention is not limited to these.
Commercial products of red phosphorus include, for example, Nova Red 120, Nova Excel 140, and Nova Quell ST100 (all manufactured by Rin Kagaku Kogyo Co., Ltd.), but are not limited thereto.
Commercially available phosphazene compounds include, for example, Ravitor FP-110 and FP-120 (all manufactured by Fushimi Pharmaceutical Co., Ltd.); and SPB-100 (all manufactured by Otsuka Chemical Co., Ltd.), but are not limited thereto. Not something.
Commercially available polyphosphonates include, for example, Nofia HM1100 and OL5000 (all manufactured by FRX), but are not limited thereto.
Examples of commercially available phosphates include, but are not limited to, MELAPUR200 (all manufactured by BASF Japan Ltd.) and the like.
Examples of commercially available phosphate esters include, but are not limited to, TPP, CDP, PX-200, and CR-733S (all manufactured by Daihachi Chemical Industry Co., Ltd.).

  The content of the component (A) is 100% by mass of the epoxy resin composition (however, when the epoxy resin composition contains the component (G), the content of the epoxy resin composition excluding the component (G) is 100% by mass). , The amount of phosphorus atom content is preferably 0.3 to 5.0% by mass, more preferably 0.5 to 4.5% by mass. When the phosphorus atom content is 0.3% by mass or more, the flame retardancy of the cured resin is further improved, and a fiber-reinforced composite material having more excellent flame retardancy is easily obtained. On the other hand, when the phosphorus atom content is 5.0% by mass or less, an epoxy resin composition having a high curing rate is easily obtained, and the heat resistance of the cured resin is further improved, and the heat resistance is more excellent. A fiber reinforced composite material having a high speed can be easily obtained.

<(B) component>
The component (B) is an epoxy resin (however, excluding a phosphorus-containing epoxy resin).
The epoxy resin is not particularly limited. For example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin, dicyclopentadiene epoxy resin, or modified epoxy resin Glycidylamine type epoxy resins such as epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, trisphenylmethane type epoxy resin (trisphenolmethane type epoxy resin), tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, tetrakis ( Other glycidyl ether type epoxy resins such as glycidyloxyphenyl) ethane and tris (glycidyloxy) methane, and Et modified epoxy resins, and phenol aralkyl type epoxy resin.
These may be used alone or in combination of two or more.

As the epoxy resin, a bifunctional epoxy resin and a trifunctional or higher epoxy resin are preferable. As the bifunctional epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and biphenyl type epoxy resin are more preferable. It should be noted that particularly excellent flame retardancy is obtained, specifically, the extremely excellent flame retardancy in which both the Total Heat Release and the Peak Heat Release described in FAR 25.853 Appendix F, Part IV are 65 or less. A bisphenol F-type epoxy resin is particularly preferred as the bifunctional epoxy resin because a fiber-reinforced composite material having the same can be easily obtained.
As a trifunctional or higher epoxy resin, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, a trisphenolmethane type epoxy resin, and a phenol aralkyl type epoxy resin are particularly preferable. Among them, an epoxy resin having a relatively small molecular weight and an epoxy equivalent is preferable from the viewpoint of obtaining more excellent flame retardancy. Specifically, the epoxy equivalent is preferably 350 or less, more preferably 300 or less, and particularly preferably 250 or less. These may be used alone or in combination of two or more.

  The content of the bifunctional epoxy resin is preferably 10% by mass or more, more preferably 15% by mass or more in 100% by mass of the component (B). The upper limit is preferably 95% by mass or less, more preferably 90% by mass or less, further preferably 85% by mass or less, and particularly preferably 80% by mass or less. When the content of the bifunctional epoxy resin is 10% by mass or more, the resin cured product can be prevented from becoming brittle, and when the content is 95% by mass or less, a resin cured product having better heat resistance can be obtained.

  The content of the trifunctional epoxy resin is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more based on 100% by mass of the component (B). Further, the upper limit is preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 85% by mass or less. When the content of the trifunctional epoxy resin is 10% by mass or more, a cured resin having better heat resistance can be obtained, and when the content is 95% by mass or less, the cured resin can be prevented from becoming brittle.

  As the epoxy resin, there is an alicyclic epoxy resin containing no aromatic ring in the molecule, but an epoxy resin having an aromatic ring tends to have a higher flame retardancy of an epoxy resin composition containing the same. is there. Therefore, as the component (B), an epoxy resin having an aromatic ring is preferable.

A commercially available product may be used as the component (B).
Commercially available epoxy resins include, for example, jER807, jER828, jER604, jER630, jER1032H60, jER152, YX-7700, YX-4000 (all manufactured by Mitsubishi Chemical Corporation); GAN, NC-2000, NC-3000 (all, Nippon Kayaku Co., Ltd.); YDPN-638, TX-0911 (all manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), Epon165 (all manufactured by Momentive Specialty Chemicals); MY-0500, MY-0600, ECN-1299 (minimum) HP-4032, HP-4700, and HP-7200 (all manufactured by DIC Corporation), but are not limited thereto.

  The content of the component (B) is preferably from 18 to 93% by mass, more preferably from 24 to 88% by mass, based on 100% by mass of the epoxy resin composition. When the content of the component (B) is 18% by mass or more, a resin cured product excellent in flame retardancy, heat resistance, and mechanical properties can be obtained. On the other hand, when the content of the component (B) is 93% by mass or less, the effect of accelerating the curing of the epoxy resin can be sufficiently obtained.

<(C) component>
The component (C) is dicyandiamide or a derivative thereof.
Dicyandiamide and its derivatives have a high melting point, and the compatibility with the epoxy resin is suppressed in a low temperature range. Further, when the epoxy resin composition contains the component (C), an excellent pot life is obtained and the mechanical properties of the cured resin are improved.

Examples of the dicyandiamide derivative include a compound in which dicyandiamide is combined with various compounds such as an epoxy resin, a vinyl compound, an acrylic compound, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Can be
These may be used alone or in combination of two or more. Moreover, you may use together with dicyandiamide.

As the component (C), dicyandiamide is preferred from the viewpoint of reactivity.
A commercially available product may be used as the component (C).
Commercial products of dicyandiamide include, for example, DICY7 and DICY15 (all manufactured by Mitsubishi Chemical Corporation), but are not limited thereto.

  The content of the component (C) is preferably such that the active hydrogen in the component (C) is 0.4 to 1.2 mol per 1 mol equivalent of the epoxy group in the epoxy resin composition, and 0.5 to 0.9 mol. Is more preferred. When the active hydrogen in the component (C) is within the above range, the curing reaction proceeds sufficiently, and the heat resistance of the cured resin product is further improved. In particular, when the active hydrogen is 0.4 mol or more per 1 mol of the epoxy group, the epoxy resin contained in the epoxy resin composition can be sufficiently cured. On the other hand, when the active hydrogen is 1.2 mol or less per 1 mol of the epoxy group, the toughness of the cured resin can be increased.

  Further, the content of the component (C) is preferably from 1 to 15 parts by mass, more preferably from 2 to 14 parts by mass, per 100 parts by mass of the component (B). When the content of the component (C) is at least 1 part by mass, the epoxy resin contained in the epoxy resin composition can be sufficiently cured. On the other hand, when the content of the component (C) is 15 parts by mass or less, the toughness of the cured resin can be increased.

<(D) component>
The component (D) is a curing accelerator having a dimethylureido group.
As a curing accelerator having a dimethylureido group, an isocyanate group and dimethylamine are generated by heating at a high temperature, and when these are an epoxy group of the component (B) (a phosphorus-containing epoxy resin is used as the component (A), There is no particular limitation as long as it activates the component (C) and the component (C). For example, an aromatic dimethylurea in which a dimethylureido group is bonded to an aromatic ring, or a dimethylureide group in which an dimethylureide group is bonded to an aliphatic compound And aliphatic dimethylurea. Among these, aromatic dimethyl urea is preferred in that the curing rate is increased.

As the aromatic dimethylurea, for example, phenyldimethylurea, methylenebis (phenyldimethylurea), and tolylenebis (dimethylurea) are preferably used. Specific examples include 4,4′-methylenebis (phenyldimethylurea) (MBPDMU), 3-phenyl-1,1-dimethylurea (PDMU), and 3- (3,4-dichlorophenyl) -1,1-dimethylurea. (DCMU), 3- (3-chloro-4-methylphenyl) -1,1-dimethylurea, 2,4-bis (3,3-dimethylureido) toluene (TBDMU) and the like. Among these, MBPDMU, TBDMU, and PDMU are more preferable from the viewpoint of the ability to accelerate curing and impart heat resistance to the cured resin.
These may be used alone or in combination of two or more.

  Examples of the aliphatic dimethylurea include dimethylurea obtained from isophorone diisocyanate and dimethylamine, dimethylurea obtained from m-xylylene diisocyanate and dimethylamine, and dimethylurea obtained from hexamethylene diisocyanate and dimethylamine. Can be

A commercially available product may be used as the component (D).
Examples of commercially available products of MBPDMU include, but are not limited to, Technology MDU-11 (above, manufactured by A & C Catalysts); Omicure (Omicure) 52 (above, manufactured by PTI Japan Co., Ltd.). Not something.
Commercially available PDMUs include, for example, Omicure 94 (above, manufactured by PTI Japan Ltd.), but are not limited thereto.
Examples of commercially available TBDMU include, but are not limited to, Omicure 24 (above, manufactured by PTI Japan Co., Ltd.).

  The content of the component (D) is preferably from 1 to 30 parts by mass, more preferably from 2 to 25 parts by mass, per 100 parts by mass of the component (B). When the content of the component (D) is at least 1 part by mass, the effect of accelerating the curing of the epoxy resin contained in the epoxy resin composition will be sufficiently obtained. On the other hand, when the content of the component (D) is 30 parts by mass or less, a resin cured product excellent in flame retardancy, heat resistance, and mechanical properties can be obtained.

<(E) component>
The component (E) is at least one curing accelerator selected from the group consisting of imidazole adduct, clathrate imidazole, microcapsule-type imidazole, and an imidazole compound coordinated with a stabilizer.
These curing accelerators have a nitrogen atom having an unshared electron pair in the structure thereof. When the curing accelerator contains a phosphorus-containing epoxy resin as the component (B), the epoxy group is also used as the epoxy group. (C) and (C) to accelerate the curing. In addition, these curing accelerators are excellent in the low-temperature region because the activity is reduced by adduct treatment, inclusion treatment with a different molecule, microcapsule treatment, or coordination of a stabilizer to commonly used imidazole. High poten- tial and high curing acceleration ability at the time of curing.
Here, the imidazole compound may be imidazole or an imidazole adduct.

  Specific examples of adduct treatment, inclusion treatment with a different molecule, microcapsule treatment, or imidazole before coordinating a stabilizer include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2 -Methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazolium tri Meritate, -Cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6- (2'-methylimidazolyl- (1 '))-ethyl-s -Triazine, 2,4-diamino-6- (2'-undecylimidazolyl- (1 '))-ethyl-s-triazine, 2,4-diamino-6- (2'-ethyl-4-methylimidazolyl- (1 ′))-Ethyl-s-triazine, 2,4-diamino-6- (2′-methylimidazolyl- (1 ′))-ethyl-s-triazine / isocyanuric acid adduct, 2-phenylimidazole / isocyanurate Acid adduct, 2-methylimidazole / isocyanuric acid adduct, 1-cyanoethyl-2-phenyl-4,5-di (2-cyanoethoxy) methyl Imidazole, 2-phenyl-4,5-dihydroxy methyl imidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole the like are exemplified, but the invention is not limited thereto.

A commercially available product may be used as the component (E).
Commercially available imidazole adducts having a structure in which an imidazole compound is ring-opened to an epoxy group of an epoxy resin include, for example, PN-50, PN-50J, PN-40, PN-40J, PN-31, PN-23, PN-H (above, manufactured by Ajinomoto Fine Techno Co., Ltd.) and the like, but are not limited thereto.
Commercial products of the clathrate imidazole include, for example, TIC-188, KM-188, HIPA-2P4MHZ, NIPA-2P4MHZ, TEP-2E4MZ, HIPA-2E4MZ, NIPA-2E4MZ (all manufactured by Nippon Soda Co., Ltd.) and the like. However, the present invention is not limited to these.
Examples of commercially available microcapsule-type imidazole include Novacure HX3721, HX3722, HX3742, and HX3748 (all manufactured by Asahi Kasei E-Materials Co., Ltd.); LC-80 (all manufactured by A & C Catalysts), and the like. It is not limited.

  Further, an imidazole compound to which a stabilizer is coordinated is, for example, an imidazole adduct manufactured by Shikoku Chemicals Co., Ltd., Cureduct P-0505 (bisphenol A diglycidyl ether / 2-ethyl-4-methylimidazole adduct). It can be prepared by combining L-07N (epoxy-phenol-borate compound) which is a stabilizer manufactured by Shikoku Chemical Industry Co., Ltd. The same effect can be obtained by using the above-described various imidazoles or imidazole compounds such as imidazole adducts instead of the cure duct P-0505. As the imidazole compound before the coordination of the stabilizing agent, a compound having low solubility in an epoxy resin is suitably used, and in this regard, Cureduct P-0505 is preferable.

  The content of the component (E) is preferably from 1 to 30 parts by mass, more preferably from 2 to 25 parts by mass, per 100 parts by mass of the component (B). When the content of the component (E) is at least 1 part by mass, the effect of accelerating the curing of the epoxy resin contained in the epoxy resin composition will be sufficiently obtained. On the other hand, when the content of the component (E) is 30 parts by mass or less, a resin cured product excellent in flame retardancy, heat resistance, and mechanical properties can be obtained.

<(F) component>
The component (F) is a thermoplastic resin.
The component (F) is added to the epoxy resin composition for the purpose of controlling the resin flow during molding and imparting toughness to the cured resin.

Examples of the component (F) include polyamide, polyester, polycarbonate, polyether sulfone, polyphenylene ether, polyphenylene sulfide, polyether ether ketone, polyether ketone, polyimide, polytetrafluoroethylene, polyether, polyolefin, liquid crystal polymer, and polyarylate. , Polysulfone, polyacrylonitrile styrene, polystyrene, polyacrylonitrile, polymethyl methacrylate, ABS, AES, ASA, polyvinyl chloride, polyvinyl formal resin, and phenoxy resin. Among these, a phenoxy resin and a polyvinyl formal resin are preferred because of excellent resin flow control properties and the like. The phenoxy resin is also preferable in terms of further enhancing the flame retardancy of the cured resin, and the polyvinyl formal resin is also preferable in that the tack of the obtained prepreg can be easily controlled to an appropriate range.
These may be used alone or in combination of two or more.

  The content of the component (F) is preferably from 1 to 50 parts by mass, more preferably from 2 to 40 parts by mass, per 100 parts by mass of the component (B). When the content of the component (F) is 1 part by mass or more, the effect of improving the physical properties is favorably exhibited. On the other hand, when the content of the component (F) is 50 parts by mass or less, the heat resistance of the cured resin product and the drapability of the prepreg are easily maintained.

<(G) component>
The component (G) is a metal hydroxide.
The metal hydroxide is not particularly limited, but examples thereof include inorganic flame retardants, and specific examples include aluminum hydroxide and magnesium hydroxide. Among these, aluminum hydroxide is preferred from the viewpoint of thermal decomposition temperature and the amount of heat absorbed during decomposition.
These may be used alone or in combination of two or more.

  As the metal hydroxide, a granular metal hydroxide is usually used. The average particle size of the metal hydroxide is preferably 15 μm or less, and more preferably 2.5 μm or less, from the viewpoint of flame retardancy and dispersibility. However, when the average particle diameter is small, the viscosity of the epoxy resin composition may be too high to make the preparation difficult. Therefore, from the viewpoint of workability, the average particle diameter of the metal hydroxide is preferably 0.01 μm or more, and more preferably 0.05 μm or more.

  The metal hydroxide may be subjected to a surface treatment as necessary. Examples of the surface treatment include a surface treatment with stearic acid and a surface treatment with a coupling agent.

As the component (G), a commercially available product may be used, or a component synthesized by a known production method may be used.
Commercial products of aluminum hydroxide include, for example, C-303, C-301N, and C-300GT (all manufactured by Sumitomo Chemical Co., Ltd.); Heidilite H-42 and H-43 (all manufactured by Showa Denko KK). But are not limited to these.
Commercially available magnesium hydroxide includes, for example, Magstar # 5, # 4, # 2, Echomag PZ-1, Z-10 (manufactured by Tateho Chemical Industry Co., Ltd.), but is not limited thereto. .

  The content of the component (G) is preferably 5% by mass or more, more preferably 10% by mass or more, in 100% by mass of the epoxy resin composition. Further, the upper limit is preferably 70% by mass or less, more preferably 60% by mass or less. When the content of the component (G) is 5% by mass or more, the flame retardancy of the epoxy resin composition is further improved. On the other hand, when the content of the component (G) is 70% by mass or less, the viscosity of the epoxy resin composition can be easily adjusted to an appropriate range, and the productivity of the prepreg increases. In addition, the mechanical properties of the fiber-reinforced composite material are kept good.

<Optional components>
The epoxy resin composition may contain various known additives as needed, as long as the effects of the present invention are not impaired.
Additives include silicone oils, wetting and dispersing agents, defoamers, defoamers, release agents such as natural waxes, synthetic waxes, metal salts of straight-chain fatty acids, acid amides, esters, paraffins, and crystals. Powders such as porous silica, fused silica, calcium silicate, alumina, calcium carbonate, talc, barium sulfate, inorganic fillers such as glass fiber and carbon fiber, coloring agents such as carbon black and red iron, silane coupling agent, etc. No.
These may be used alone or in combination of two or more.

<Physical properties of epoxy resin composition>
The epoxy resin composition of the present invention is used for producing a prepreg by impregnating a reinforcing fiber aggregate, for example, as described later.
The viscosity of the epoxy resin composition at 60 ° C. is preferably 10 Pa · s or more, from the viewpoint of adjusting the tackiness of the obtained prepreg surface and controlling the fluidity of the resin at the time of molding (suppression of turbulence of the reinforcing fibers), and 20 Pa or more. S or more, more preferably 30 Pa s or more. In addition, from the viewpoints of impregnation into the reinforcing fiber aggregate and moldability of the prepreg, 3000 Pa · s or less is preferable, 2900 Pa · s or less is more preferable, and 2800 Pa · s or less is further preferable.
The viscosity of the epoxy resin composition at 60 ° C. is measured, for example, with a rotary viscometer using a 25 mmφ parallel plate, at a plate gap of 500 μm, at a heating rate of 2 ° C./min, at an angular velocity of 10 rad / sec, and at a stress of 300 Pa. It is required by

<Production method of epoxy resin composition>
The epoxy resin composition of the present invention can be obtained, for example, by mixing the above-mentioned components.
Examples of a method for mixing the components include a method using a mixer such as a three-roll mill, a planetary mixer, a kneader, a homogenizer, and a homodisper.

<Effects>
The epoxy resin composition of the present invention described above contains the above-mentioned components (A), (B), (C), (D) and (E), and thus has excellent curability. Further, by using the epoxy resin composition of the present invention, a fiber-reinforced composite material having excellent flame retardancy and heat resistance can be obtained.
Since the epoxy resin composition of the present invention is excellent in curability, it can be sufficiently cured, for example, at 150 ° C. within 20 minutes.

"Molding"
The molded article of the present invention is obtained by molding the above-described epoxy resin composition of the present invention.
Examples of the molding method of the epoxy resin composition include an injection molding method (including insert molding of a film and a glass plate), an injection compression molding method, an extrusion method, a blow molding method, a vacuum molding method, a pressure molding method, and a calender molding. And an inflation molding method. Among these, the injection molding method and the injection compression molding method are preferred because they are excellent in mass productivity and can obtain molded products with high dimensional accuracy.

Since the molded article of the present invention is formed by molding the epoxy resin composition of the present invention, it is excellent in flame retardancy and heat resistance.
The molded article of the present invention can be applied to, for example, a housing of a mobile device, a vehicle product, a furniture product, a building material product, and the like.

"Prepreg"
The prepreg of the present invention is obtained by impregnating a reinforcing fiber assembly with the above-described epoxy resin composition of the present invention.
The content of the epoxy resin composition based on the total weight of the prepreg (hereinafter, referred to as “resin content”) is preferably 15 to 50% by mass, more preferably 20 to 45% by mass, and still more preferably 25 to 40% by mass. When the resin content is 15% by mass or more, sufficient adhesion between the reinforcing fiber aggregate and the epoxy resin composition can be ensured, and when the resin content is 50% by mass or less, the flame retardancy is further improved.

The reinforcing fibers constituting the reinforcing fiber aggregate are not particularly limited, and may be appropriately selected from those known as reinforcing fibers constituting the fiber-reinforced composite material according to the use and the like.For example, carbon fiber, aramid fiber, nylon Various inorganic fibers or organic fibers such as fibers, high-strength polyester fibers, glass fibers, boron fibers, alumina fibers, and silicon nitride fibers can be used. Among these, from the viewpoint of flame retardancy, carbon fiber, aramid fiber, glass fiber, boron fiber, alumina fiber, and silicon nitride fiber are preferable, and carbon fiber is preferable in terms of specific strength, specific elasticity, and excellent electromagnetic wave shielding properties. Particularly preferred.
These may be used alone or in combination of two or more.

As will be described in detail later, when the fiber reinforced composite material obtained by curing the prepreg of the present invention is used for a part or all of the structure, the strand tensile strength of the carbon fiber is 1 in view of the rigidity of the fiber reinforced composite material. It is preferably from 0.0 to 9.0 GPa, more preferably from 1.5 to 9.0 GPa, and the strand tensile modulus of the carbon fiber is preferably from 150 to 1000 GPa, more preferably from 200 to 1000 GPa.
The strand tensile strength and the strand tensile modulus of the carbon fiber are measured according to JIS R 7601 (1986).

  The form of the reinforcing fiber aggregate is not particularly limited, and may be a form used as a base material of a normal prepreg.For example, the reinforcing fibers may be one in which the reinforcing fibers are aligned in one direction, and may be a woven or nonwoven fabric. Or non-crimp fabric.

  Since the prepreg of the present invention is obtained by impregnating the reinforcing fiber aggregate with the epoxy resin composition of the present invention, it is possible to obtain a fiber-reinforced composite material having excellent flame retardancy and heat resistance by curing.

`` Fiber reinforced composite material ''
The fiber-reinforced composite material of the present invention is obtained by curing the above-described prepreg of the present invention.
Since the fiber-reinforced composite material is excellent in flame retardancy, heat resistance, electromagnetic wave shielding property, mechanical properties, and the like, it is preferable that the fiber-reinforced composite material contains carbon fiber as a reinforcing fiber.

  The fiber-reinforced composite material can be produced by a known method using the prepreg of the present invention, and examples of the production method include an autoclave molding method, a vacuum bag molding method, and a press molding method. Among these, the press molding method is preferred from the viewpoint that the characteristics of the epoxy resin composition of the present invention can be sufficiently utilized, and that a high-quality fiber-reinforced composite material can be easily obtained.

When producing a fiber-reinforced composite material by press molding, the prepreg of the present invention, or a preform prepared by laminating the prepreg of the present invention, is sandwiched between molds adjusted to a curing temperature in advance, and heated and pressed to form a prepreg. Alternatively, it is preferable to cure the preform.
The temperature in the mold at the time of press molding is preferably 100 to 160 ° C. Further, it is preferable to cure the prepreg or the preform under the conditions of 1 to 15 MPa for 1 to 20 minutes.

Since the fiber-reinforced composite material of the present invention contains a cured product of the epoxy resin composition of the present invention, it has excellent flame retardancy and heat resistance. Regarding flame retardancy, for example, when a fiber-reinforced composite material molded plate having a thickness of about 1 mm is formed, it is possible to achieve V-0 or V-1 level flame retardancy at UL-94V. In particular, when the epoxy resin composition contains the component (G), a higher level of flame retardancy can be achieved. Specifically, it can pass a combustion test according to the FAR 25.853 Appendix F, Part IV standard, which requires even higher flame retardancy than UL-94V.
Therefore, the fiber reinforced composite material of the present invention is useful in applications requiring high flame retardancy. Such applications include, for example, housings for electric and electronic equipment, interior materials for aircraft and automobiles, and the like.
Further, since the fiber-reinforced composite material of the present invention also has excellent heat resistance, it is highly useful in applications where excellent heat resistance is required in addition to high flame retardant performance. It is preferably used for such purposes.

"Structure"
The structure of the present invention is partially or entirely composed of the above-described fiber-reinforced composite material of the present invention. That is, the structure of the present invention may be composed only of the fiber-reinforced composite material of the present invention, or may be formed of a fiber-reinforced composite material of the present invention and another material (for example, metal, injection-molded thermoplastic resin). And the like).

Since the structure of the present invention is partially or entirely composed of the fiber-reinforced composite material of the present invention, it has excellent flame retardancy and heat resistance.
The structure of the present invention can be applied to, for example, a housing for electric / electronic equipment, an interior member of an aircraft or an automobile, and the like.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
The raw materials used in the examples and comparative examples are shown below.

"material"
<(A) component>
FX-289FA: "FX-289FA" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., containing a phosphorus-containing epoxy resin and a phosphorus atom content of 7.4% by mass.

<(B) component>
-TX-0911: Liquid phenol novolak type epoxy resin, epoxy equivalent 172g / eq, "TX-0911" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
JER152: Liquid phenol novolak type epoxy resin, epoxy equivalent 172 g / eq, "jER152" manufactured by Mitsubishi Chemical Corporation.
JER828: Liquid bisphenol A type epoxy resin, epoxy equivalent 189 g / eq, "jER828" manufactured by Mitsubishi Chemical Corporation.

<(C) component>
• DICY15: dicyandiamide, active hydrogen equivalent 21 g / eq, “jER Cure DICY15” manufactured by Mitsubishi Chemical Corporation.

<(D) component>
-Omicure 94: Phenyldimethylurea, "Omicure 94" manufactured by PTI Japan Ltd.

<(E) component>
-PN-50: "PN-50" manufactured by Ajinomoto Fine Techno Co., Ltd., imidazole adduct, softening temperature 115 ° C.
-TIC-188: Inclusion imidazole, the host molecule is 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, "TIC-188" manufactured by Nippon Soda Co., Ltd.

<(F) component>
-YP-70: Phenoxy resin, "YP-70" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.

<Carbon fiber>
-Carbon fiber: "Pyrofil TR50S15L" manufactured by Mitsubishi Rayon Co., Ltd.

"Example 1"
FX-289FA as component (A), TX-0911, jER152 and jER828 as component (B), DICY15 as component (C), Omicure 94 as component (D), PN-50 as component (E) and PN-50 as component (F) Using YP-70, an epoxy resin composition was prepared as follows.
First, according to the composition shown in Table 1, component (B) (liquid), component (C) (solid), component (D) (solid) and component (E) (solid) were combined with a solid component and a liquid component. Was weighed into a container such that the mass ratio of the mixture became 1: 1 and the mixture was stirred and mixed. This was further finely mixed with a three-roll mill to obtain a curing agent master batch.
Subsequently, of the compositions shown in Table 1, components other than the curing agent master batch were weighed in a flask, and heated to 140 ° C. using an oil bath to dissolve and mix. Thereafter, when cooled to about 65 ° C., the curing agent masterbatch was added and mixed by stirring to obtain an epoxy resin composition.
Using the obtained epoxy resin composition, a resin plate, a prepreg, and a fiber reinforced composite material plate were produced according to <Epoxy resin plate production method>, <prepreg production method>, and <fiber reinforced composite material plate production method> described below. . Various measurements and evaluations were performed according to the <Evaluation method> described below. Table 1 shows the results.

"Example 2, Comparative Examples 1-4"
An epoxy resin composition was prepared in the same manner as in Example 1 except that the composition was changed to the composition shown in Table 1, and a resin plate, a prepreg, and a fiber-reinforced composite material plate were prepared, and various measurements and evaluations were performed. Table 1 shows the results.

<Epoxy resin plate manufacturing method>
The uncured epoxy resin composition was cured at an oven atmosphere temperature of 150 ° C. × 10 minutes (heating rate was 10 ° C./min) to produce a resin plate having a thickness of 2 mm.

<Prepreg manufacturing method>
The uncured epoxy resin composition was formed into a film with a comma coater (“M-500” manufactured by Hirano Techseed Co., Ltd.) to prepare a resin film having a resin basis weight of 26.8 g / m ² . This resin film is laminated on both sides of a carbon fiber sheet having a fiber weight of 125 g / m ² obtained by aligning carbon fibers, and impregnated with a heating roll to obtain a fiber weight of 125 g / m ² and a resin content of 30% by mass. Prepreg was obtained.

<Fiber reinforced composite material plate manufacturing method>
The prepreg obtained in the above <prepreg production method> was cut into 298 mm × 298 mm, and the fiber direction was [0 ° / 90 ° / 0 ° / 90 ° / 0 ° / 0 ° / 90 ° / 0 ° / 90 ° / 0 °] to obtain a laminate. This laminate was put into a press molding die preheated to 150 ° C., and press-molded under the conditions of 150 ° C. × 10 minutes and a pressure of 10 MPa to obtain a 1.1 mm-thick fiber-reinforced composite material plate ([0 ° / 90 ° / 0 ° / 90 ° / 0 ° / 0 ° / 90 ° / 0 ° / 90 ° / 0 °]).

<Evaluation method>
(1) Calculation of Curing Degree and Curing Time of Epoxy Resin Composition by Isothermal Differential Scanning Calorimetry (Isothermal DSC) Measurement The calorific value of the uncured epoxy resin composition during the curing reaction was measured by isothermal DSC to determine the degree of curing. The cure time was evaluated.
FIG. 1 schematically shows an example of a heat flow curve 1 of curing heat generation at a constant temperature. In temperature curve 3 in the cell, to the approximate straight line temperature curve in the Atsushi Nobori process, the intersection consisting extension of the approximate straight line temperature curve isothermal starting point t ₀ of isothermal holding time. The portion surrounded by any baseline 2 and the heat flow curve 1 represents the heat generated by curing reaction starts heat generation at time t _s (curing reaction starting), fever ends at time t _e (curing reaction completion) to Suppose you have Curing degree alpha _i at time _{t i} the middle curing, as the ratio to the total calorific value _{[Delta] H total} calorific value [Delta] H _i from the curing reaction starting point _{t s} to time _{t i,} can be calculated from the following equation (1). The calorific value ΔH _i is determined by the trapezoidal rule of the quadrature. The time until the curing degree α _i is reached is the time from the start of the isothermal holding time t ₀ .

To determine the degree of cure and the time to reach each degree of cure from the measured DSC heat flow curve 1, each time was defined as follows.
Curing reaction end time t _e is set to the time t _i the heat flow value of one thousandth of a peak top in a heat flow curve 1. Baseline 2 was a line drawn horizontally from the heat flow of the curing reaction end time t _e. When t ₀ ≧ 0, the time at which the baseline 2 and the heat flow curve 1 first intersect was defined as a curing reaction start time t _s . In the section of t _s and _{t s,} determine the [Delta] H _i in [Delta] H _total, and any time _{t i,} was determined degree of cure alpha _i from the equation (1).

  The heat flow curve 1 was obtained by using a differential scanning calorimeter (DSC) (TA Instruments Japan Co., Ltd., “Q-1000”) to dispense about 10 mg of the resin composition into an aluminum hermetic pan. Then, an empty aluminum hermetic pan is placed on the sample table in the cell as a reference and heated from 20 ° C. to 150 ° C. at a heating rate of 200 ° C./min. And got. In addition, the sampling rate of the heat flow was set to 0.1 minute. Curing time of 90% curing degree is within 10 minutes, curing time of 95% curing degree is within 15 minutes, curing time of 98% curing degree is within 18 minutes, and curing time of 100% curing degree is within 20 minutes. Passed.

(2) Measurement of Glass Transition Temperature of Epoxy Resin Composition by Differential Scanning Calorimetry (DSC) The glass transition temperature (Tg) of the uncured epoxy resin composition was measured by a differential scanning calorimeter (DSC) (TA Instruments). The measurement was performed in a nitrogen atmosphere using "Q-1000" manufactured by Men Japan Co., Ltd.). The heating rate was 10 ° C./min, and the measuring temperature range was −20 ° C. to 50 ° C. Based on the method described in JIS K 7121, the midpoint of the portion where the DSC curve shows a step change was defined as Tg of the epoxy resin composition.

(3) Measurement of DMA G'-Tg (Measurement of Tg of resin plate)
A resin plate having a thickness of 2 mm obtained by the method for preparing an epoxy resin plate was processed into a test piece having a length of 55 mm and a width of 12.7 mm. Using a rheometer (“ARES-RDS”, manufactured by TA Instruments Japan Co., Ltd.), the storage elastic modulus G ′ of the test specimen was measured at a measurement frequency of 1 Hz and a heating rate of 5 ° C./min. A logarithmic plot was plotted against the temperature, and the temperature determined from the intersection of the approximate line of the flat region of logG 'and the approximate line of the region where G' transitions was recorded as DMA G'-Tg. This is defined as Tg of the resin plate. Higher DMA G'-Tg means better heat resistance.

(4) Evaluation of bending characteristics of resin plate A resin plate having a thickness of 2 mm obtained by the method for producing an epoxy resin plate was processed into a test piece having a length of 60 mm and a width of 8 mm. Using a universal testing machine (manufactured by Instron) equipped with a three-point bending jig (3.2 mmR for both the indenter and the support and a distance between supports of 32 mm) for the test piece, the resin was used at a crosshead speed of 2 mm / min. The bending characteristics (bending strength, flexural modulus, maximum load elongation (bending strain), breaking elongation (breaking strain)) of the plate were measured.

(5) UL-94V Burning Test of Resin Plate A resin plate having a thickness of 2 mm obtained by the method for producing an epoxy resin plate was processed into a length of 127 mm and a width of 12.7 mm to obtain a test piece. The test specimen was subjected to a combustion test according to UL-94V standard using a combustion tester (manufactured by Suga Test Instruments Co., Ltd.). Specifically, the test piece was vertically attached to a clamp, and a flame contact with a 20 mm flame was performed for 10 seconds, and the burning time was measured. A combustion test was performed on five test pieces, and the number of samples that burned up to the clamp, the maximum value (max) of each burning time, and the total of the five burning times (total burning time: total) were recorded. In addition, judgments [V-0, V-1, V-2, fail] were made based on the results. As for the flame retardancy, V-0 is the most excellent, and is inferior in the order of V-1, V-2, and fail.

  In Table 1, "phosphorus atom content (% by mass)" indicates the phosphorus atom content (% by mass) in 100% by mass of the epoxy resin composition. The "active hydrogen equivalent ratio" indicates the ratio of the amount (mol) of active hydrogen in the component (C) to 1 mol equivalent of the epoxy group in the epoxy resin composition. The "urea equivalent ratio" indicates the ratio of the amount (mol) of the urea group in the component (D) to 1 mol equivalent of the epoxy group in the epoxy resin composition.

As is clear from the results in Table 1, the epoxy resin compositions of Examples 1 and 2 were excellent in curability. Moreover, the Tg of the resin plate produced using these epoxy resin compositions was high, and was excellent in heat resistance. These resin plates were excellent in flame retardancy and bending properties.
On the other hand, the epoxy resin compositions of Comparative Examples 1 and 2 containing no component (D) had a slow curing rate. In addition, resin plates produced using these epoxy resin compositions had low Tg and were inferior in bending characteristics (particularly bending strength, bending strain, and breaking strain).
The epoxy resin compositions of Comparative Examples 3 and 4 containing no component (C) had a slow curing rate. In addition, the resin plates produced using these epoxy resin compositions had low Tg.

1: Heat Flow Curve 2: Baseline 3: temperature curve t _0: the starting point of isothermal holding time t _s: curing reaction starting time t _i: the middle setting time t _e: to time _{t i:} curing reaction end time [Delta] H _i Calorific value ΔH _total : total calorific value

Claims (12)

An epoxy resin composition comprising the following components (A), (B), (C), (D) and (E).
(A) component: phosphorus compound (B) component: epoxy resin (C) component: dicyandiamide or a derivative thereof (D) component: a curing accelerator having a dimethylureido group (E) component: imidazole adduct, clathrate imidazole, microcapsule At least one curing accelerator selected from the group consisting of an imidazole compound and an imidazole compound coordinated with a stabilizer   The epoxy resin composition according to claim 1, wherein the component (D) is at least one compound selected from the group consisting of phenyldimethylurea, methylenebis (phenyldimethylurea), and tolylenebis (dimethylurea).   The component (C) comprises 1 to 15 parts by mass, the component (D) 1 to 30 parts by mass, and the component (E) 1 to 30 parts by mass with respect to 100 parts by mass of the component (B). 3. The epoxy resin composition according to 1 or 2.   In the epoxy resin composition 100% by mass (however, when the epoxy resin composition contains a metal hydroxide, the component (A) in the epoxy resin composition 100% by mass excluding the metal hydroxide) is a phosphorus atom. The epoxy resin composition according to any one of claims 1 to 3, wherein the epoxy resin composition contains an amount of 0.3 to 5.0% by mass.   The component (A) according to any one of claims 1 to 4, wherein the component (A) is at least one phosphorus compound selected from the group consisting of a phosphorus-containing epoxy resin, red phosphorus, a phosphazene compound, a polyphosphonate, a phosphate, and a phosphate ester. The epoxy resin composition according to claim 1. The epoxy resin composition according to any one of claims 1 to 5, further comprising the following component (F).
Component (F): thermoplastic resin   The epoxy resin composition according to claim 6, wherein the component (F) is at least one of a phenoxy resin and a polyvinyl formal resin. The epoxy resin composition according to any one of claims 1 to 7, further comprising the following component (G).
Component (G): metal hydroxide   A molded article obtained by molding the epoxy resin composition according to any one of claims 1 to 8. A prepreg obtained by impregnating a reinforcing fiber aggregate with the epoxy resin composition according to any one of claims 1 to 8 ,
A prepreg, wherein the reinforcing fibers constituting the reinforcing fiber aggregate are carbon fibers .   A fiber-reinforced composite material obtained by curing the prepreg according to claim 10.   A structure partially or wholly composed of the fiber-reinforced composite material according to claim 11.

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