JP5468853B2 - Composite material - Google Patents

Description

The present invention is an epoxy resin composition relating to the composite using prepreg obtained by a matrix resin, particularly suitable for a structural material for prepreg for aircraft. More particularly, excellent mechanical properties of heat resistance and compression systems, has high wet heat resistance, in particular to multi case material using the epoxy resin composition for aircraft structural materials.

A fiber reinforced composite material using carbon fiber, aromatic polyamide fiber, or the like as a reinforcing material has a feature of high strength and rigidity as compared with a material not using a reinforcing material (reinforced fiber). Various methods are currently used for the production of fiber reinforced composite materials, and a method using a prepreg, which is a sheet-like intermediate base material in which a reinforced fiber is impregnated with a matrix resin, is widely used. In this method, a plurality of prepregs are laminated in an arbitrary direction and then heated to obtain a molded product of a fiber-reinforced composite material having high strength and rigidity. These composite materials are often used, for example, as structural materials for aircraft and the like, taking advantage of their excellent physical properties.

As the matrix resin, a thermosetting resin or a thermoplastic resin is used. Among them, a thermosetting resin excellent in handleability is often used, and an epoxy resin is most often used. In a prepreg using an epoxy resin (epoxy resin-based prepreg), for example, as one component (main component) of the matrix resin, an aromatic glycidylamine type epoxy resin and as the other component (curing agent) of the matrix resin, diaminodiphenyl Composite materials that provide superior heat resistance, mechanical properties, dimensional stability, chemical resistance, and weather resistance in combination with sulfone are provided. As described above, it has been recognized that composite materials made from epoxy resin prepregs exhibit good performance, but it is also known that matrix resins have low elongation and are brittle. Therefore, it is pointed out that the mechanical properties of the composite material are inferior, and it is required to improve the mechanical properties without reducing the heat resistance.

One of the important mechanical properties when using a composite material as a structural material is compressive strength. Compressive strength is measured using a test piece such as a non-perforated plate or a perforated plate. However, in actual use, it is often in the form of a plate with a bolt hole. Compressive strength, especially strength under high temperature and high humidity conditions is important for industrial use.

In general, it is known that polymer-based materials have lower strength and elastic modulus under high temperature or high humidity conditions. Therefore, the mechanical properties of the fiber-reinforced composite material having a polymer as a matrix resin are also likely to be lowered under high temperature or high humidity conditions. However, when the composite material is applied as a structural material such as an aircraft, it is required to sufficiently maintain mechanical properties, particularly compressive strength, even under high temperature or high humidity conditions.

In order to improve the compressive strength of the composite material, it is generally effective to increase the elastic modulus of the matrix resin. Increasing the elastic modulus of the cured epoxy resin can be made by taking into consideration the characteristics of the raw materials to be blended. However, generally cured epoxy resin with high elastic modulus has low toughness and is brittle, so impact resistance, especially compressive strength after impact, and fatigue are reduced. There is a limit. On the other hand, when a fiber reinforced composite material is used as a structural material, impact resistance is also important as described above. For example, when these fiber reinforced composite materials are used for primary structural materials for aircraft, they may be subject to external impacts due to pebbles jumping up during takeoff and landing, tool dropping during maintenance, etc. Improving impact resistance without reducing it is also an important issue.

When trying to obtain a molded article having impact resistance, it goes without saying that the elongation of the reinforcing material itself such as carbon fiber is improved. On the other hand, increasing the toughness of the matrix resin used in the prepreg is pointed out as an important point, and many attempts have been made to improve the matrix resin. When hardened epoxy resin cured products that increase the compressive strength after impact of the composite material are used as the matrix resin, these materials generally cannot have a high modulus of elasticity, so a fiber-reinforced composite material having a high compressive strength can be used. I can't get it. That is, it can be said that the composite material most demanded in the industry is a cured epoxy resin having both high rigidity and high toughness so that the compressive strength and post-impact compressive strength of the composite material are increased.

In Patent Document 1, two types of epoxy resin compositions are used in the production of prepregs, that is, the surface layer involved in impact resistance and fatigue uses a highly toughened epoxy resin composition, and the inner part contributes to compressive strength. Discloses an improvement in compressive strength by using an epoxy resin composition having a high elastic modulus as a cured product. However, it is essential to produce two types of epoxy resin compositions, and it can be pointed out that labor and cost are required in the production of matrix resins and prepregs, which is disadvantageous for industrial use. Patent Document 2 discloses a prepreg excellent in compressive strength and post-impact compressive strength using non-circular cross-sectional carbon fibers. However, since the cross-sectional shape of the carbon fiber is limited and does not correspond to the circular shape that is a general cross-sectional shape of the carbon fiber, it is not suitable for industrial use.

As described above, while maintaining heat resistance, both high compressive strength, especially perforated plate compressive strength, and high impact resistance, especially compressive strength after impact, are compatible with general-purpose reinforcing fibers for manufacturing. Hassle-free epoxy resin compositions and prepreg materials have not yet been obtained.

JP-A-8-225666 International Publication No. 96/21695 Pamphlet

An object of the present invention, while maintaining the heat resistance, mechanical properties of the compression system, excellent impact resistance with particularly excellent in perforated plate compressive strength in wet heat, provides a suitable fiber-reinforced composite materials as structural materials It is to be.

The composite material of the present invention that meets the above object is an epoxy resin composition containing at least the following components [A], [B], and [C], and includes at least the following components [A] and [B]. An epoxy resin composition containing component [C],
30% by weight or more and less than 70% by weight of the total epoxy resin component in the epoxy resin composition is component [A], and 30% by weight or more and less than 70% by weight of the total epoxy resin component in the epoxy resin composition , A trifunctional or higher functional epoxy resin other than the component [A], the epoxy resin of the component [A] is N, N, O-triglycidyl-m-aminophenol, and the component [C] Ether sulfone or polyether imide [C1] and polyamide [C2], component [C] is 10 to 50% by weight of the total epoxy resin composition, and component [C1] is an epoxy resin composition 5 to 25% by weight of the total, and the component [C2] is 5 to 25% by weight of the entire epoxy resin composition, and the resin composition is cured under the following molding conditions. Cure The glass transition point (glass transition point before moisture absorption treatment, Tgdry) is 200 ° C. or more, the flexural modulus measured under room temperature conditions (25 ° C., 50% RH) is 3.0 GPa or more, and the bending strength is A composite material obtained by molding and curing a prepreg obtained by impregnating a reinforcing fiber base material with an epoxy resin composition characterized by having a physical property of 130 MPa or more.
Component [A]: epoxy resin represented by the following formula (1)

(In the above formula (1), Ar represents an aromatic group having 6 to 20 carbon atoms.)
Component [B]: 3,3′-diaminodiphenylsulfone Component [C]: Thermoplastic resin Molding conditions: Autoclave molding, pressure 0.49 MPa, temperature 180 ° C., time 120 minutes

The composite material of the present invention is a fiber-reinforced composite material that is suitable as a structural material because it has excellent heat resistance, mechanical properties of a compression system, particularly excellent perforated plate compression strength during wet heat, and excellent impact resistance. .

The epoxy resin composition used in the present invention is an epoxy resin composition containing at least a specific epoxy resin component [A], an epoxy resin curing agent component [B], and a thermoplastic resin component [C], and has predetermined molding conditions. When measured under room temperature conditions (25 ° C., 50% RH) at 200 ° C. or higher when the glass transition point (glass transition point before moisture absorption treatment, T _g ^dry ) of the cured product when cured under Has a physical property of 3.0 GPa or more and a bending strength of 130 MPa or more. The predetermined molding condition is defined as autoclave molding under a pressure of 0.49 MPa, a temperature of 180 ° C., and a time of 120 minutes. Bending measurement at room temperature is defined as bending measurement in an atmosphere of 25 ° C. and 50% RH. By using an epoxy resin composition satisfying such conditions as a matrix resin, the prepreg which has the heat resistance and heat-and-moisture resistance of the matrix resin itself, and can provide high mechanical properties such as high compression properties and impact properties, and The composite material is obtained.

The epoxy resin composition used in the present invention is a resin composition in which the cured product has a glass transition point (glass transition point before moisture absorption treatment, T _g ^dry ) of 200 ° C. or higher. More preferably, it is 205 ° C. or higher. Here a glass transition point referred to as ^{_(T g dry)} is cured to 20 ° C., a _{T g} of the time measured after conditioned for 40 hours or more during the RH 50% atmosphere. More specifically, a cured product obtained by curing the resin composition at 180 ° C. for 2 hours under the above conditions was cut into a length of 50 mm, a width of 6 mm, and a thickness of 3 mm to prepare a test piece. After adjusting the humidity in an atmosphere of 20 ° C. and 50% RH for 40 hours or more, using a DMA measuring device (Rheogel-E4000 manufactured by UBM Co., Ltd.), the temperature rising rate and frequency at 3 ° C./min by three-point bending This is a peak temperature of loss viscoelasticity (E ″) obtained by measuring a resin composition with a strain of 1 Hz (evaluation standard: EN6032 compliant).

Furthermore, the resin composition whose glass transition point ( ^Tgwet ) after the moisture absorption process of the hardened | cured material of an epoxy resin composition is 150 ^degreeC or more is especially preferable. More preferably, it is 155 ° C. or higher. Here, the glass transition point (Tg ^wet ) after moisture absorption treatment is Tg of the cured resin after pressure cooker treatment, that is, exposure for 24 hours in an atmosphere of 121 ° C. and saturated vapor pressure.

The epoxy resin composition in the present invention has a glass transition point Tg ^dry of a cured product cured under the above conditions of 200 ° C. or higher, a flexural modulus at room temperature of 3.0 GPa or higher, and a bending strength of 130 MPa. That's all. Further, the cured product has physical properties such that the glass transition point Tg ^wet after the moisture absorption treatment under high temperature and high humidity conditions (121 ° C., saturated vapor pressure, 24 hours) is 150 ° C. or higher. Further, the cured product is subjected to moisture absorption under high temperature and high humidity conditions (121 ° C., saturated vapor pressure, 24 hours), and then the flexural modulus measured at high temperature (82 ° C.) is 2.5 GPa or more, and Those having physical properties such that the bending strength is 70 MPa or more are also preferable. A cured resin having a flexural modulus of less than 3.0 GPa at room temperature and a flexural strength of less than 130 MPa is not suitable because the compressive strength of the fiber-reinforced composite material may decrease.

In the epoxy resin composition of the present invention, the density of the cured product obtained under the curing conditions is preferably 1.25 g / cm ³ or more. When the density is less than 1.25 g / cm ³ , the compressive strength of the fiber reinforced composite material may be significantly reduced. More preferably, it is 1.26 g / cm ³ or more.

When a fiber reinforced composite material is used as a structural material, it is necessary that a decrease in physical properties under high temperature conditions after moisture absorption is small. Therefore, in the present invention, the cured product cured under the above conditions is subjected to a moisture absorption treatment under high-temperature and high-humidity conditions (121 ° C., saturated vapor pressure, 24 hours), and then bending measured at a high temperature (82 ° C.). Those having physical properties such that the elastic modulus is 2.5 GPa or more and the bending strength is 70 MPa or more are preferable. A cured product having a flexural modulus of less than 2.5 GPa at a high temperature condition after moisture absorption treatment and a bending strength of less than 70 MPa is a case where the compressive strength at a high temperature condition after moisture absorption treatment is significantly reduced when a fiber reinforced composite material is used. There is. The bending measurement under the high temperature condition after the moisture absorption treatment is defined as the bending measurement in an atmosphere at 82 ° C. after moisture absorption treatment at 121 ° C. and saturated vapor pressure for 24 hours.

Next, components [A] to [C] used in the epoxy resin composition for structural materials used in the present invention will be described in detail.

Component [A] is an epoxy resin represented by the formula (1). In the formula (1), Ar represents an aromatic group having 6 to 20 carbon atoms, and the aromatic group is a non-reactive functional group. It may contain a group. Examples of the aromatic group include a phenylene group, a diphenylene group, a naphthylene group, a diphenylene ether group, a diphenylene sulfone group, a diphenylene indan group, and a diphenylene amide group.

In order to realize a high elastic modulus of the cured resin, a trifunctional epoxy resin as shown by the formula (1) is preferable. Specifically, triglycidylaminophenol type epoxy (commercially available as Sumitomo Chemical's Sumiepoxy ELM-100 (trade name), ELM-120 (trade name), Japan Epoxy Resin Corporation jER630 (trade name), Huntsman Araldite MY0500 (trade name), Araldite MY0510 (trade name), Araldite MY0600 (trade name), Araldite MY0610 (trade name)), glycidylamine-type epoxy resins such as triglycidylaminocresol, and naphthalene-type epoxy resins Can be mentioned. In addition, an epoxy resin having a rigid skeleton, for example, an epoxy resin having a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, or the like in the molecule is preferable because a higher elastic modulus can be realized. Among these, one or two or more can be blended and used. In particular, in order to realize a high elastic modulus of the cured resin, it is preferable to use a triglycidylaminophenol type epoxy, and particularly N, N, O-triglycidyl-m-aminophenol is preferable.

Furthermore, in order to realize better heat resistance of the cured resin and excellent bending elastic modulus and bending strength under high temperature conditions after moisture absorption treatment, 30% by weight or more of all epoxy resin components in the epoxy resin composition Preferably less than 70% by weight is component [A]. When the ratio of the component [A] in the epoxy resin component is 70% by weight or more, or less than 30% by weight, the physical properties of the obtained cured product or composite material after high-temperature and high-humidity treatment may be deteriorated. . However, depending on the balance with other physical properties, a trifunctional or higher functional epoxy resin other than the component [A] may be used in the range of 30% by weight to less than 70% by weight of the total epoxy resin component in the epoxy resin composition. Good.

As the epoxy resin other than the component [A] used in the epoxy resin composition used in the present invention , any conventionally known epoxy resin excluding the trifunctional epoxy resin having a glycidylamino group as in the above component [A] can be used. It can be used and is not particularly limited. Bifunctional epoxy resins such as bisphenol type epoxy resin, alcohol type epoxy resin, biphenyl type epoxy resin, hydrophthalic acid type epoxy resin, dimer acid type epoxy resin, alicyclic epoxy resin, tetrakis (glycidyloxyphenyl) ethane, tris (glycidyl) Glycidyl ether type epoxy resin such as oxyphenyl) methane, glycidylamine type epoxy resin such as tetraglycidyldiaminodiphenylmethane, naphthalene type epoxy resin, novolac type epoxy resin such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, etc. Moreover, polyfunctional epoxy resins, such as a phenol type epoxy resin, etc. are mentioned. Furthermore, various modified epoxy resins such as urethane-modified epoxy resin and rubber-modified epoxy resin can also be used.

Examples of the bisphenol type epoxy resin include bisphenol A type resin, bisphenol F type resin, bisphenol AD type resin, bisphenol S type resin and the like. More specifically, jER815 (product name), jER828 (product name), jER834 (product name), jER1001 (product name), jER807 (product name) manufactured by Japan Epoxy Resin Co., Ltd., and EPOMIC R-710 (product name) manufactured by Mitsui Petrochemical Co., Ltd. Name), EXA1514 (trade name) manufactured by Dainippon Ink & Chemicals, Inc. can be exemplified.

Examples of the alicyclic epoxy resin include Araldite CY-179 (trade name), CY-178 (trade name), CY-182 (trade name), and CY-183 (trade name) manufactured by Huntsman.

As a phenol novolac type epoxy resin, Japan Epoxy Resin's jER152 (trade name), jER154 (trade name), Dow Chemical's DEN431 (trade name), DEN485 (trade name), DEN438 (trade name), DIC Corporation As cresol novolak type epoxy resin such as Epicron N740 (trade name), Araldite ECN1235 (trade name), ECN1273 (trade name), ECN1280 (trade name), EOCN102 (trade name), EOCN103, manufactured by Nippon Kayaku Co., Ltd. (Product name), EOCN104 (product name), etc. can be illustrated.

Examples of the various modified epoxy resins include urethane modified bisphenol A epoxy resins such as Adeka Resin EPU-6 (trade name) and EPU-4 (trade name) manufactured by Asahi Denka.

Epoxy resins other than these components [A] can be appropriately selected and used alone or in combination. Among these, bifunctional epoxy resins typified by bisphenol types have various grades ranging from liquid to solid depending on the difference in molecular weight. When blended in a prepreg matrix resin, the viscosity is adjusted by mixing them appropriately. It is the target ingredient.

Next, the epoxy resin curing agent of component [B] will be described. The epoxy resin is usually used together with a known curing agent, but the same applies to the present invention. The epoxy resin curing agent used in the present invention is not particularly limited as long as it is usually used as a curing agent for epoxy resins, but an aromatic amine curing agent is preferable. Specifically, diaminodiphenyl sulfone (DDS), diaminodiphenylmethane (DDM), diaminodiphenyl ether (DPE), phenylenediamine and the like are used as a curing agent for the epoxy resin. Further, for example, a derivative of an aromatic amine curing agent such as dimethyldiethyl DDM, tetraethyl DDM, diethyldiisopropyl DDM or the like is not particularly limited as long as it can cope with 180 ° C. curing, and any conventionally known aromatic amine It can also be used as a system curing agent. In order to obtain a cured product having a high elastic modulus and heat resistance, it is preferable to use diaminodiphenyl sulfone as a curing agent, and it is particularly preferable to use 3,3′-diaminodiphenyl sulfone among its isomers. Particularly preferred.

The component [B] can also be DDS (mc-DDS) microencapsulated with a coating agent. In order to prevent the mc-DDS from reacting with the epoxy resin at room temperature, the surface layer of the DDS particles is less reactive with the epoxy resin by physical and chemical bonding, specifically, polyamide, modified urea resin , Coated with modified melamine resin, polyolefin, polyparaffin (including modified products), and the like. These coating agents may be used alone or in combination, and DDS microencapsulated with various coating agents other than those described above can also be used.

As long as the effect of the present invention is not impaired, a curing agent other than the above-described component [B], a curing accelerator, a thermosetting resin, a reactive diluent, a filler, an anti-aging agent, a difficulty, as necessary. Various additives such as a flame retardant and a pigment may be contained. Other epoxy resin curing agents and / or curing accelerators other than component [B] include basic curing agents such as acid anhydrides, Lewis acids, dicyandiamide (DICY) and imidazoles, urea compounds, organometallic salts, etc. Is mentioned. More specifically, examples of the acid anhydride include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Examples of the Lewis acid include boron trifluoride salts, and more specifically, BF ₃ monoethylamine, BF ₃ benzylamine, and the like. Examples of imidazoles include 2-ethyl-4-methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole, and 2-phenylimidazole. In addition, urea compounds such as 3- [3,4-dichlorophenyl] -1,1-dimethylurea (DCMU) and 1,1-4 (methyl-m-phenylene) bis (3,3-dimethylurea) Examples thereof include Co [III] acetylacetonate which is an organic metal salt. Examples of the reactive diluent include reactive diluents such as polypropylene diglycol / diglycidyl ether and phenyl glycidyl ether.

The blending amount of the component [B] used in the present invention takes into consideration the presence or absence and addition amount of a curing agent / curing accelerator other than the component [B], the chemical reaction stoichiometry with the epoxy resin, and the curing rate of the composition. Thus, it can be appropriately used in a desired amount.

Next, the thermoplastic resin of component [C] will be described. As the thermoplastic resin used in the epoxy resin composition used in the present invention , in addition to thermoplastic resins represented by polyethersulfone (PES) and polyetherimide (PEI), polyimide, polyamideimide, polysulfone, polycarbonate, Polyether ether ketone, polyamide such as nylon 6, nylon 12, amorphous nylon, aramid, arylate, polyester carbonate and the like can be mentioned. Among these, polyimide, polyetherimide (PEI), polyethersulfone (PES), polysulfone, and polyamideimide can be cited as more preferable examples from the viewpoint of heat resistance.

The form of the thermoplastic resin is not particularly limited, but is preferably in the form of particles in order to be added to the epoxy resin composition while maintaining homogeneity and moldability. The average particle size of the thermoplastic resin fine particles is preferably in the range of 0.1 to 100 μm. If it is less than 0.1 μm, the bulk density increases, and the viscosity of the epoxy resin composition may increase significantly, or it may be difficult to add a sufficient amount. On the other hand, when the obtained epoxy resin composition is made into a sheet form having a thickness of more than 100 μm, it may be difficult to obtain a sheet having a uniform thickness. More preferably, the average particle size is 1 to 50 μm.

The compounding amount of the component [C] used in the present invention is preferably 10 to 50% by weight of the total epoxy resin composition. When the amount of component [C] is less than 10% by weight, the resulting prepreg and composite material have insufficient impact resistance. If it exceeds 50% by weight, the resin cured product may undergo phase transition, resulting in a decrease in mechanical properties, and the viscosity of the resin composition may increase, resulting in inferior moldability and handleability. Preferably, it is 14 to 40% by weight.

Furthermore, these thermoplastic resins can be dissolved at least partially in the epoxy resin (the epoxy resin other than the component [A] and / or the component [A]) (the component [C1]) and cannot be dissolved. (Component [C2]). As the thermoplastic resin [C1] that is at least partially soluble in the epoxy resin other than the component [A] and / or the component [A], for example, when a polyfunctional epoxy resin having a glycidylamino group is used, polyethersulfone (PES), polyetherimide (PEI) and the like.

Component [C1] dissolves in the epoxy resin during the curing process, increases the viscosity of the matrix, and also has the effect of preventing a decrease in the viscosity of the epoxy resin composition. Component [C1] is preferably a terminal-reactive thermoplastic resin from the viewpoints of toughness, high temperature and high humidity resistance and chemical resistance. In the present invention, the thermoplastic resin is soluble or insoluble in the epoxy resin means that the thermoplastic resin is poured into the epoxy resin in the form of pellets, pulverized material or powder, and stirred when the temperature is lower than the curing temperature. The case where the size does not change is defined as insoluble, and the case where the size of the particle decreases or disappears is defined as at least partially soluble.

When component [C1] is used, it is in a state where it is not dissolved in the epoxy resin at all (a state where it is dispersed as fine particles in the entire epoxy resin composition), a part of component [C1] is dissolved, and the rest is the entire epoxy resin composition It may be added in a state of being dispersed in a state of being completely dissolved. From the viewpoint of the moldability of the epoxy resin composition and the handleability of the prepreg, it is more preferable that the epoxy resin composition is added in a state where it is not dissolved at all or in a state where it is partially dissolved. The dissolved ratio can be appropriately set in consideration of the moldability of the epoxy resin composition and the prepreg handling property as described above, and is not particularly limited.

It is preferable that the compounding quantity of component [C1] used by this invention is 5 to 25 weight% of all the epoxy resin compositions. When the amount of component [C1] is less than 5% by weight, the resulting composite material has insufficient impact resistance. When the content exceeds 25% by weight, phase transition occurs in the cured resin and mechanical properties and chemical resistance may be deteriorated, and the viscosity of the resin composition becomes high and the moldability and handleability are poor. There is. Preferably, it is 8 to 20% by weight.

As the thermoplastic resin [C2] insoluble in the epoxy resin other than the component [A] and / or the component [A], for example, when a polyfunctional epoxy resin having a glycidylamino group is used, polyether ether ketone (PEK) And polyamides such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon 6, nylon 12, amorphous nylon, and amorphous polyimide.

The thermoplastic resin [C1] soluble in the epoxy resin and the insoluble thermoplastic resin [C2] may be melt blended in advance, and pulverized and mixed as particles.

It is preferable that the compounding quantity of component [C2] used by this invention is 5 to 25 weight% of all the epoxy resin compositions. When the amount of component [C] is less than 5% by weight, the resulting composite material has insufficient impact resistance. If it exceeds 25% by weight, a phase transition occurs in the cured resin and mechanical properties may be lowered, and the viscosity of the resin composition may be increased, resulting in inferior moldability and handleability. Preferably, it is 6 to 20% by weight.

The blending of the thermoplastic resin is an essential component for the purpose of improving impact resistance while hardly reducing the heat resistance of the cured product obtained by curing the epoxy resin composition according to the present invention. However, the component [C1] and the component [C2] are selected by a specific combination with the epoxy resin other than the component [A] and / or the component [A].

Components other than the above component [A], component [B] and component [C] can also be added in any amount within a range not impairing the mechanical properties of the obtained molded product. For example, as the inorganic filler, but are not particularly limited, and a carbon material such as carbon nanotubes and fullerenes, fused silica _(SiO 2), crystalline silica _(SiO 2), magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), boron nitride (BN), aluminum nitride (AlN), etc. In addition to these, high dielectric constant fillers such as high dielectric constant barium titanate and titanium oxide, and hard Ferrite, magnetic filler such as hard ferrite, magnesium hydroxide, aluminum hydroxide, antimony trioxide, antimony pentoxide, guanidine salt, zinc borate, molybdenum compound, zinc stannate and other inorganic flame retardants, talc, Barium sulfate, calcium carbonate, mica powder and the like can be used. Similarly, the organic filler is not particularly limited, but silicon rubber (single, including powder-like one), cross-linked acrylic rubber (single), and a core-shell structure using this as a core. Is mentioned. The core-shell structure refers to a structure in which a core layer made of a rubbery polymer such as silicon rubber or crosslinked acrylic rubber is covered with a shell layer made of a glassy polymer. These fillers can be used alone or in combination of two or more. It is also possible to add rubber components represented by carboxy-terminated styrene butadiene rubber and carboxy-terminated hydrogenated acrylonitrile butadiene rubber. These rubber components can be used alone or in combination of two or more at any ratio.

The production method of the epoxy resin composition used in the present invention is not particularly limited, and any conventionally known method may be used. For example, the kneading temperature applied during the production of the epoxy resin composition can be exemplified by a range of 10 to 160 ° C. When the temperature exceeds 160 ° C., thermal deterioration of the epoxy resin or partial curing reaction starts, and the storage stability of the resulting epoxy resin composition and the prepreg using the epoxy resin composition may decrease. When it is lower than 10 ° C., the viscosity of the epoxy resin composition is high, and it may be difficult to knead substantially. Preferably it is 20-130 degreeC, More preferably, it is the range of 30-110 degreeC.

A conventionally well-known thing can be used as a kneading machine apparatus. Specific examples include a roll mill, a planetary mixer, a kneader, an extruder, a Banbury mixer, a mixing vessel provided with a stirring blade, a horizontal mixing vessel, and the like. The kneading of each component can be performed in the air or in an inert gas atmosphere. In particular, when kneading is performed in the air, an atmosphere in which temperature and humidity are controlled is preferable. Although not particularly limited, for example, it is preferable to knead in a low humidity atmosphere such as a temperature controlled at a constant temperature of 30 ° C. or lower or a relative humidity of 50% RH or lower.

The kneading of each component may be performed in a single stage, or may be performed in multiple stages by sequential addition. Moreover, when adding sequentially, it can add in arbitrary orders. Among these, as described above, the component [C1] may be provided after a part or all of the component [A1] and / or the epoxy resin other than the component [A] is dissolved in advance. it can. Moreover, although not specifically limited, it is preferable from the viewpoint of the storage stability of the resulting epoxy resin composition and the prepreg comprising the component [B] as the kneading / adding order.

Next, a description will be given up prepreg.

The prepreg of the present invention, the error epoxy resin composition having excellent moist heat resistance and the like obtained as described above, a prepreg formed by impregnating a reinforcing fiber substrate (fiber reinforcement). The fiber reinforcement used in prepreg in the present invention, carbon fibers, glass fibers, aromatic polyamide fibers, polyimide fibers, polybenzoxazole fibers, and wholly aromatic polyester fibers and the like. These can be used alone or in combination of two or more. Although not particularly limited, in order to improve the mechanical properties of the composite material, it is preferable to use carbon fibers having excellent tensile strength. The form of the fiber reinforcement is a woven fabric, a one-way aligned product, or the like. In particular, a unidirectional fabric sheet made of carbon fibers or a combination of carbon fibers and other fibers is preferred.

The prepreg used in the present invention preferably has an epoxy resin composition content (RC) of 15 to 60% by weight. If it is less than 15% by weight, voids or the like are generated in the obtained composite material, and the mechanical properties may be deteriorated. If it exceeds 60% by weight, the reinforcing effect by the reinforcing fibers becomes insufficient, and the mechanical properties in comparison with weight may be substantially low. Preferably it is the range of 20-50 mass%, More preferably, it is the range of 25-50 weight%. The epoxy resin composition content (RC) here is a ratio calculated from the change in weight due to decomposition of the prepreg by sulfuric acid decomposition and decomposition of the resin. More specifically, a prepreg is cut out to 100 mm × 100 mm to prepare a test piece, the weight thereof is measured, and the resin remaining in the sulfuric acid is immersed or boiled until the resin component is eluted, and the fiber remaining after filtration is sulfated. It is the content rate of the epoxy resin composition obtained by measuring the weight after washing | cleaning by and drying, and calculating.

Further, although not particularly limited, specific preferred prepreg forms include, for example, a reinforcing fiber layer made of an epoxy resin composition impregnated between reinforcing fibers and the reinforcing fibers, and the surface of the reinforcing fiber layer. And a resin coating layer having a thickness of 2 to 50 μm. When the thickness is less than 2 μm, tackiness becomes insufficient, and the molding processability of the prepreg may be significantly lowered. If it exceeds 50 μm, it will be difficult to wind the prepreg into a roll with a uniform thickness, and the molding accuracy may be significantly reduced. More preferably, it is 5-45 micrometers, More preferably, it is 10-40 micrometers.

The prepreg used in the present invention is not particularly limited, and can be produced using any conventionally known method. The epoxy resin composition of the present invention is applied to a release paper in a thin film form, The resin film obtained by peeling is laminated on a reinforcing fiber sheet and impregnated with the epoxy resin composition, so-called hot melt method, or the epoxy resin composition is made into a varnish using an appropriate solvent, A solvent method for impregnating reinforcing fibers can be mentioned. Among these, the prepreg of the present invention can be particularly preferably produced by a hot melt method which is a conventionally known production method.

The d epoxy resin composition as a method for the epoxy resin composition sheet is not limited in particular, it can also be used any conventionally known method. More specifically, it can be obtained by casting and casting on a support such as release paper or film by die extrusion, applicator, reverse roll coater, comma coater or the like. The resin temperature at the time of film formation can be appropriately set according to the resin composition / viscosity, but the same conditions as the kneading temperature in the aforementioned epoxy resin composition production method can be suitably used.

The term “reinforcing fiber sheet” as used herein refers to a form of a fiber reinforcing material, and is a sheet-like reinforcing fiber such as a woven fabric or a one-way aligned article as described above. The size of these reinforcing fiber sheets and the epoxy resin composition sheet is not particularly limited.

In the case of continuous production, the production speed is not particularly limited, but is 0.1 m / min or more in consideration of productivity, economy, and the like. More preferably, it is 1 m / min or more, More preferably, it is 5 m / min or more.

As the impregnation pressure for impregnating the reinforcing fiber sheet with the epoxy resin composition sheet, any pressure can be used in consideration of the viscosity, resin flow, etc. of the epoxy resin composition.

The impregnation temperature of the epoxy resin composition sheet into the reinforcing fiber sheet is in the range of 50 to 150 ° C. When it is less than 50 ° C., the viscosity of the epoxy resin composition sheet is high, and the reinforcing fiber sheet may not be sufficiently impregnated. When the temperature is 150 ° C. or higher, the curing reaction of the epoxy resin composition is started, and the storage stability of the prepreg may be reduced, or the drapeability may be reduced. More preferably, it is 60-145 degreeC, More preferably, it is 70-140 degreeC. Further, the impregnation can be performed in multiple stages at an arbitrary pressure and temperature in a plurality of times instead of once.

The composite material of the present invention produced by molding and curing such as lamination using the prepreg obtained by such means has high moisture and heat resistance properties, and further excellent impact resistance, and is used for aircraft. It is suitable for structural material applications.

Hereinafter, the present invention will be described in more detail with reference to examples. In the examples and comparative examples, various test methods for the epoxy resin composition were performed as follows.

(1) Glass transition point (Tg ^dry ) before moisture absorption treatment
A cured product obtained by curing each resin composition at 180 ° C. for 2 hours was cut into a length of 50 mm, a width of 6 mm, and a thickness of 3 mm to prepare a test piece. After conditioning this test piece in an atmosphere of 20 ° C. and 50% RH for 40 hours or more, using a DMA measuring apparatus (Rheogel-E4000 manufactured by UBM), the temperature was raised at 3 ° C./min by three-point bending. Measurement was performed with a strain of speed and frequency of 1 Hz. In addition, Tg evaluation was performed based on EN6032 which employ | adopts the peak top of loss viscoelasticity (E ").

(2) Glass transition point after moisture absorption treatment (Tg ^wet )
The test piece of (1) was measured by the same method as (1) except that the test piece was exposed for 24 hours at 121 ° C. and saturated vapor pressure.

(3) Moisture absorption condition of test piece for bending measurement The thickness of each cured epoxy resin composition obtained by molding each epoxy resin composition at a pressure of 0.49 MPa at a temperature of 180 ° C. for 120 minutes. After cutting into a size of 3 mm, width 10 mm, and length 70 mm, moisture absorption treatment was performed for 24 hours under the conditions of 121 ° C. and saturated vapor pressure.

(4) Bending measurement of cured resin The bending elastic modulus and strength of the cured product of each epoxy resin composition were measured using an autoclave molding method at a pressure of 0.49 MPa and a temperature of 180 ° C. for 120 minutes. A plate of the obtained cured product was produced. Thereafter, a test piece cut to a size of 3 mm in thickness, 10 mm in width, and 70 mm in length was prepared, and the test piece subjected to the above-mentioned moisture absorption treatment at room temperature conditions (25 ° C., 50% RH) by three-point bending with a span of 48 mm Each was subjected to a bending measurement under a high temperature condition (82 ° C.).

(5) Density measurement of cured resin The size of a cured product obtained by molding for 120 minutes at a pressure of 0.49 MPa and a temperature of 180 ° C. using an autoclave molding method is 3 mm thick, 6 mm wide and 50 mm long. Then, the density was measured by the water displacement method. At this time, the water temperature is also measured and calculated using the density corresponding to the water temperature. From these measured values, the density of the cured resin was calculated using the following formula.

Density of cured product of epoxy resin composition (g / cm ³ ) = [(W1 / (W1-W2)] × d
W1: Weight of cured epoxy resin composition in air (g)
W2: Weight of cured epoxy resin composition in water (g)
d: Density of water at the measured water temperature (g / cm ³ )

(6) Measurement of post-impact compressive strength (CAI) of composite material Evaluation of post-impact compressive strength was measured in accordance with ASTM D7136 / D7136M as an index of impact resistance. That is, the prepreg was cut and laminated to obtain a laminated body of a laminated structure [+ 45/0 / −45 / 90] _3S , using a normal autoclave molding method, a pressure of 0.49 MPa, a temperature of 180 ° C., and a time of 120 minutes. Molded. The obtained molded product was cut into dimensions of 152.4 mm in the 0 ° direction and 101.6 mm in the 90 ° direction to obtain test pieces for compressive strength after impact (CAI) test. Using this test piece, the post-impact compressive strength (CAI) after 26J impact was measured at room temperature (25 ° C., 50% RH).

(7) Perforated plate compressive strength (OHC) measurement cut and lamination were performed to obtain a laminate of a laminate configuration [+ 45/0 / −45 / 90] _2S . Using a normal autoclave molding method, molding was performed at a pressure of 0.49 MPa and a temperature of 180 ° C. for 120 minutes. The obtained molded product was cut into a rectangular shape with a 0 ° direction of 305 mm and a 90 ° direction of 34.8 mm, and a circular hole with a diameter of 6.25 mm was drilled in the center to form a perforated plate. (25 ° C., 50% RH) and using a 10T autograph tester manufactured by Shimadzu under high temperature conditions after moisture absorption (a test piece immersed in warm water at 71 ° C. for 2 weeks was measured in an atmosphere of 82 ° C.) Measured.

[Examples 1 to 5 and Comparative Examples 1 and 2]
Among the components of the epoxy resin composition, as the component [A], glycidylamine type epoxy resin manufactured by Huntsman: Araldite MY0600 is used as an epoxy resin other than the component [A], and glycidylamine type epoxy manufactured by Japan Epoxy Resin Co., Ltd. Resin: Ep604, bisphenol A type epoxy resin: Ep828, Adeka's urethane-modified epoxy resin: EPU-6, component [B], Wakayama Seika Kogyo aromatic amine curing agent: Seikacure-S (4 4′-DDS), DDS micro-encapsulated with a coating agent (mc-DDS, coating rate is 10 wt%), aromatic amine curing agent manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: DAS (3,3′-DDS) In addition, as component [C1], polyethersulfone manufactured by Sumitomo Chemical Co., Ltd .: PES5003P (average particle size 10 μm) ), Polyetherimide (PEI) manufactured by Japan GE Plastics: Ultem 1000-1000 as component [C2], grill amide manufactured by Emschemy Japan: TR-55, thermoplastic polyimide manufactured by Mitsui Chemicals: Aurum PD450M As other additives, a curing agent manufactured by Japan Epoxy Resin Co., Ltd .: DICY7T and a curing accelerator manufactured by Hodogaya Chemical Co., Ltd .: DCMU-99 were used.

In Examples 1 to 5 and Comparative Examples 1 and 2, various raw materials were blended according to the following procedure so as to have the compositions shown in Table 1. First, the component [A] having the composition shown in Table 1 below and a part or all of the component [C1] were heated and dissolved in a kneader. Thereafter, the obtained resin mixture was transferred to a roll mill, and component [B], dispersion component [C1], component [C2], and other additive components were well kneaded on the roll mill. Examples 1 to 5 and comparison The epoxy resin compositions of Examples 1 and 2 were obtained.

The Tg of the cured product of this epoxy resin composition before and after the moisture absorption treatment and the bending characteristics under the room temperature and the high temperature conditions after the moisture absorption treatment were measured. The cured product of the epoxy resin composition was molded by using an autoclave molding method at a pressure of 0.49 MPa and a temperature of 180 ° C. for 120 minutes. And the test piece which cut hardened | cured material into the size of thickness 3mm, width 10mm, and length 70mm was obtained. The obtained test piece was subjected to three-point bending measurement with a span of 48 mm.

The measurement results were as shown in Table 1. As shown in Table 1, the specimens obtained in Examples 1 to 5 were both high in bending elastic modulus and bending strength, and particularly high in high temperature bending characteristics after moisture absorption treatment. As for the test piece obtained in the above, both values were low.

Similarly, the cured epoxy resin compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were cut to obtain test pieces for resin density measurement. The obtained test piece was subjected to density measurement by the above method. As a result, as shown in Table 1, the resin density was high for the test pieces obtained in Examples 1 to 5, but the test piece obtained in Comparative Examples 1 and 2 was low.

Next, each of the epoxy resin compositions of Examples 1 to 5 and Comparative Examples 1 and 2 was applied onto a release film using a film coater, and a resin with a release film having a basis weight of 51.0 g / m ^2. A sheet was produced.

Carbon fiber bundle (manufactured by Toho Tenax, Tenax IMS60,
Tensile strength 5490 MPa, elastic modulus 289 GPa) are arranged and sandwiched between the two resin sheets obtained in Examples 1 to 5 and Comparative Examples 1 and 2, and heated and impregnated at a temperature of 100 ° C. and a pressure of 0.3 MPa. A unidirectional prepreg having a carbon fiber basis weight of 190 g / m ² and a resin content of 35% by weight was obtained.

Cut the unidirectional prepreg by the epoxy resin compositions of Examples 1 to 5 and Comparative Examples 1 and 2 obtained by the above method, and then laminate to produce a molded plate, and the obtained composite material CAI The perforated plate compressive strength at room temperature and high temperature conditions after moisture absorption was evaluated. The results are shown in Table 1. Both the CAI and the perforated plate compressive strength of the test pieces obtained in Examples 1 to 5 were high, but these values were low in the test pieces obtained in Comparative Examples 1 and 2. .

Claims (6)

An epoxy resin composition comprising at least the following component [A], component [B], and component [C],
30% by weight or more and less than 70% by weight of the total epoxy resin component in the epoxy resin composition is component [A], and 30% by weight or more and less than 70% by weight of the total epoxy resin component in the epoxy resin composition , A trifunctional or higher functional epoxy resin other than the component [A], the epoxy resin of the component [A] is N, N, O-triglycidyl-m-aminophenol, and the component [C] Ether sulfone or polyether imide [C1] and polyamide [C2], component [C] is 10 to 50% by weight of the total epoxy resin composition, and component [C1] is an epoxy resin composition 5 to 25% by weight of the total, and the component [C2] is 5 to 25% by weight of the entire epoxy resin composition, and the resin composition is cured under the following molding conditions. Cure Glass transition temperature (moisture absorption treatment before the glass transition _point, ^{T g dry)} at the 200 ° C. or higher, at room temperature conditions (25 ℃, 50% RH) in the flexural modulus as measured under the above 3.0 GPa, and bending A composite material obtained by molding and curing a prepreg obtained by impregnating a reinforcing fiber base material with an epoxy resin composition having physical properties such that the strength is 130 MPa or more .
Component [A]: epoxy resin represented by the following formula (1)

(In the above formula (1), Ar represents an aromatic group having 6 to 20 carbon atoms.)
Component [B]: 3,3'-diaminodiphenylsulfone Component [C]: Thermoplastic resin molding conditions: autoclave molding, pressure 0.49 MPa, temperature 180C, time 120 minutes The glass transition point (glass transition point after moisture absorption treatment, T _g ^wet ) after moisture absorption treatment (121 ° C., saturated vapor pressure, 24 hours) of the cured product under high temperature and high humidity conditions is 150 ° C. or higher. The composite material according to claim 1, wherein the composite material has physical properties . The cured product is subjected to moisture absorption treatment under high temperature and high humidity conditions (121 ° C., saturated vapor pressure, 24 hours), and then the flexural modulus measured at high temperature (82 ° C.) is 2.5 GPa or more and the bending strength is 70 MPa. The composite material according to claim 1, wherein the composite material has physical properties as described above . The composite material according to any one of claims 1 to 3 , wherein the reinforcing fiber substrate is a carbon fiber. The composite material according to any one of claims 1 to 3, wherein the reinforcing fiber base is a unidirectional carbon fiber sheet. The composite material according to any one of claims 1 to 3, wherein the reinforcing fiber substrate is a carbon fiber woven sheet or a woven sheet composed of a plurality of types of fibers.