JP2009102563A - Epoxy resin composition and fiber-reinforced composite material by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition excellent in resin-impregnating property at a relatively low temperature of ≤60°C, since having a low viscosity elevation, and excellent in productivity since becoming a cured material capable of being demolded in a short time of within 1 hr, and a fiber-reinforced composite material excellent in surface designing property by using the same. <P>SOLUTION: This epoxy resin composition containing at least (A) the epoxy resin and (B) a curing agent is provided wherein the curing agent (B) contains 30 to 90 mass% bis(4-amino-3-methylcyclohexyl)methane and 70 to 10 mass% norbornane diamine based on 100 mass% total curing agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an epoxy resin composition suitably used for a fiber-reinforced composite material, and a fiber-reinforced composite material obtained using the same.

  Fiber reinforced composite materials (hereinafter abbreviated as FRP) consisting of reinforced fibers and matrix resins can be designed using the advantages of reinforced fibers and matrix resins. Widely used in fields such as general industrial fields.

  As the reinforcing fiber, glass fiber, aramid fiber, carbon fiber, boron fiber or the like is used. As the matrix resin, either a thermosetting resin or a thermoplastic resin is used, but a thermosetting resin that can be easily impregnated into the reinforcing fiber is often used. As such a thermosetting resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, bismaleimide resin, cyanate resin and the like are used.

  For the production of FRP, methods such as a prepreg method, a hand lay-up method, a filament winding method, a pultrusion method, and an RTM (Resin Transfer Molding) method are applied.

  Among these, the RTM method, which is a method of injecting a liquid thermosetting resin composition into a reinforcing fiber base disposed in a mold and heat-curing, has a great advantage that an FRP having a complicated shape can be formed.

  When FRP is used for automobiles, especially hoods (bonnets), roofs, trunk lids, doors and other outer panels, not only the functional aspects such as excellent mechanical properties such as light weight, strength and elastic modulus, Also on the design surface, it is required to have a smooth surface on which the mapping is clearly projected.

  However, there has been a problem that it is difficult to obtain a smooth surface when an FRP is produced using a reinforcing fiber substrate having irregularities such as a woven fabric or knitted fabric of reinforcing fibers. This is a phenomenon in which unevenness reflecting a woven or knitted pattern such as woven fabric or knitted fabric is generated on the surface of the FRP, and this unevenness is called “print through”. This cause is due to two factors: shrinkage accompanying the curing reaction of the matrix resin, and thermal shrinkage when cooling from the curing temperature to room temperature. That is, since the thickness of the matrix resin in the concave portion of the reinforcing fiber base is larger than the thickness of the matrix resin in other portions, the shrinkage amount becomes larger in the concave portion of the reinforcing fiber base, and as a result, the FRP surface has irregularities. It will occur.

Thermal shrinkage, which is one of the factors that cause unevenness on the FRP surface, is the amount of heat shrinkage ΔL (μm), the thickness of the matrix resin L (μm), the linear expansion coefficient of the matrix resin α (K ⁻¹ ), When the temperature difference between the curing temperature and room temperature is ΔT (K), ΔL = α × L × ΔT. Therefore, when reducing the amount of heat shrinkage and reducing the irregularities on the surface of the FRP, the curing temperature is low, and the closer to room temperature, the more advantageous.

  For the above reasons, room temperature curing type epoxy resin compositions are most advantageous in reducing the amount of heat shrinkage, and epoxy resins using linear aliphatic polyamines, alicyclic polyamines, mercaptans, etc. as the curing agent. The composition is disclosed (for example, refer nonpatent literature 1, patent documents 1-3).

  However, these epoxy resin compositions disclosed in Non-Patent Document 1 and Patent Documents 1 to 3 require a long time of about 7 days for curing at room temperature. Therefore, when FRP is produced by the RTM method, there is a problem that the impregnation property to the reinforcing fiber base is extremely bad and an unimpregnated portion is formed. Furthermore, linear aliphatic polyamines and mercaptans used as curing agents have the drawback that the molecular skeleton itself is flexible and the resulting resin cured product has low heat resistance.

  On the other hand, as a thermosetting epoxy resin composition that can be cured at a relatively low temperature of 100 ° C. or lower, a mixture comprising a low-temperature active type curing agent at 40 to 70 ° C. and a high-temperature active type curing agent at 120 to 170 ° C. An epoxy resin composition using a system curing agent (see, for example, Patent Document 4), a thermosetting latent curing agent activated at 100 ° C. or less, and an amine curing agent necessary for secondary curing at high temperature An epoxy resin composition is disclosed (for example, see Patent Document 5).

  However, the epoxy resin compositions shown in these patent documents require a long time of 0.5 to 2 hours for the primary curing necessary for demolding, so that the productivity is still insufficient and the epoxy resin composition is suitable for prepregs. Since it is a viscosity composition, it is not suitable for a method requiring low viscosity like the RTM method.

  Further, among the thermosetting epoxy resin composition, it comprises a bifunctional or higher aromatic epoxy resin, an aromatic polyamine compound and / or an alicyclic polyamine compound, and has a low viscosity applicable to the RTM method, An epoxy resin composition compatible with curing within 2 hours at 200 ° C. is disclosed (for example, Patent Document 6).

  However, in this patent document, a specific composition that allows curing within one hour at a relatively low temperature of 60 ° C. or less, and curing at a relatively low temperature of 60 ° C. or less reduces the amount of heat shrinkage, and thus There is no suggestion about improving the designability of FRP.

Therefore, at a relatively low temperature of 60 ° C. or lower, the epoxy resin composition that can be cured in a short time within 1 hour, and also has good impregnation to the reinforcing fiber substrate, and the surface irregularities of FRP are small, and the design There is a demand for FRP having excellent properties.
Soichi Muroi and Shuichi Ishimura, Introductory Epoxy Resin 1st Edition 2nd Edition, Kobunshi Publishing Co., Ltd., pages 73-84 Japanese Patent Publication No. 7-49572 Japanese Patent Laid-Open No. 6-248053 JP-A-8-253556 Japanese Patent Publication No. 7-121989 JP 2003-96163 A International Publication No. 00/53654 Pamphlet

  In view of the current situation as described above, the object of the present invention is to provide a cured product that is excellent in resin impregnation because of a small increase in viscosity at a relatively low temperature of 60 ° C. or lower, and that can be removed in a short time within 1 hour. It is an object to provide an epoxy resin composition having excellent productivity and a fiber-reinforced composite material having small heat shrinkage and excellent surface design by using the epoxy resin composition.

  That is, the present invention is an epoxy resin composition containing at least an epoxy resin (A) and a curing agent (B), wherein the curing agent (B) is bis (4- It is an epoxy resin composition comprising 30 to 90% by mass of amino-3-methylcyclohexyl) methane and 70 to 10% by mass of norbornanediamine, and a fiber-reinforced composite material obtained by using the epoxy resin composition.

  According to the epoxy resin composition of the present invention, a fiber-reinforced composite material having excellent surface design can be formed in a short time.

  The inventors of the present invention have greatly improved resin injection workability and impregnation into reinforcing fibers than before by using an epoxy resin composition in which an alicyclic polyamine curing agent having a specific structure is blended at a specific ratio. Furthermore, since it can be cured within 1 hour, it is excellent in productivity, and the obtained FRP has also been found to have excellent surface design properties, leading to the present invention.

  Hereinafter, preferred embodiments of the present invention will be described. In the present invention, “epoxy resin” refers to a compound having two or more epoxy groups in one molecule. In addition, an epoxy resin composition in which elements necessary for polymerization or curing reaction are mixed is referred to as an “epoxy resin composition”, and an epoxy resin cured product in which polymerization or curing reaction has been performed (hereinafter simply referred to as “resin cured product”, It may be referred to as “cured product” or “cured product of epoxy resin composition”. The “polyamine” means a compound having a plurality of amine nitrogen atoms in the molecule and a plurality of active hydrogens. “Active hydrogen” refers to a hydrogen atom bonded to an aminic nitrogen atom.

  The epoxy resin composition of the present invention comprises at least an epoxy resin (A) and a curing agent (B), and the curing agent (B) is bis (4-amino-3-methyl) with respect to 100% by mass of the total curing agent. (Cyclohexyl) methane must be contained in an amount of 30 to 90% by mass, and norbornanediamine in an amount of 70 to 10% by mass. The curing agent (B) includes other components other than bis (4-amino-3-methylcyclohexyl) methane and norbornanediamine such as alicyclic polyamine, linear aliphatic polyamine, and aromatic polyamine. It is not necessary to be composed only of bis (4-amino-3-methylcyclohexyl) methane and norbornanediamine, but such other components are 20% of 100% by mass of the total curing agent (B). It is preferably less than mass%, more preferably less than 10 mass%. Moreover, the said other component does not need to be substantially contained in the hardening | curing agent (B).

  In general, polyamine-based curing agents are classified into aliphatic, alicyclic, aromatic and the like from the chemical structure, and the basicity becomes weaker in this order, so that a high temperature is required for curing with the epoxy resin. Specifically, aliphatic polyamines are suitable for curing at room temperature to 50 ° C, alicyclic polyamines at room temperature to 100 ° C, and aromatic polyamines at 100 ° C or higher. The bis (4-amino-3-methylcyclohexyl) methane represented by the formula (1) and the norbornanediamine represented by the formula (2) used as the curing agent (B) of the present invention are converted from the chemical structure to the alicyclic polyamine. being classified. Here, bis (4-amino-3-methylcyclohexyl) methane is a steric hindrance in which two amino groups in the molecule are bonded to a tertiary carbon and a methyl group is bonded to the ring structure. Therefore, reactivity with an epoxy resin is low among alicyclic polyamines. On the other hand, norbornanediamine has both two amino groups in the molecule bonded to the primary carbon, so the reactivity with the epoxy resin is higher than that of the aliphatic polyamine bonded to the secondary carbon or tertiary carbon. . For this reason, when the compounding amount of bis (4-amino-3-methylcyclohexyl) methane is within the above range, the viscosity of the epoxy resin composition is prevented from excessively increasing, and norbornanediamine is within the above range. Then, the curing time is shortened and the curing can be performed within one hour. That is, when the blending amounts of bis (4-amino-3-methylcyclohexyl) methane and norbornanediamine in the present epoxy resin composition are only within the above range, blending each of them alone or blending of other polyamine curing agents Thus, it is possible to achieve both an increase in the viscosity of the liquid resin at a low temperature, which could not be achieved, and a short-time curing within 1 hour.

  In the epoxy resin composition of the present invention, when the blending amount of bis (4-amino-3-methylcyclohexyl) methane is less than 30% by mass with respect to 100% by mass of the total curing agent, the viscosity of the epoxy resin composition is increased. On the other hand, if it exceeds 90% by mass, it may not be cured within 1 hour. Further, when norbornanediamine is less than 10% by mass with respect to 100% by mass of the total curing agent, it may not be cured within 1 hour. On the other hand, when it exceeds 70% by mass, the viscosity of the epoxy resin composition is greatly increased. May be.

  In addition, bis (4-amino-3-methylcyclohexyl) methane is that all amino groups in the alicyclic polyamine molecule are directly bonded to carbon constituting the ring structure, and norbornanediamine is a ring. Since the structure has a bridge structure, there is an advantage that the heat resistance and mechanical properties of the FRP can be improved.

  Commercial products of bis (4-amino-3-methylcyclohexyl) methane include commercial products of norbornanediamine such as “Ancamine” (registered trademark) 2049 (Air Products and Chemicals) and Lalomin C-260 (BASF). Examples thereof include “NBDA” (registered trademark) (Mitsui Chemicals).

  The curing agent (B) in the present invention may contain other polyamines in addition to bis (4-amino-3-methylcyclohexyl) methane and norbornanediamine. Specific examples of other polyamines that can be contained in the curing agent (B) include bis (4-aminocyclohexyl) methane, alicyclic polyamines other than norbornanediamine, linear aliphatic polyamines, and aromatic polyamines. Specific examples of other aliphatic polyamines that can be contained in the curing agent (B) include mensendiamine (formula (3)), isophoronediamine (formula (4)), N-aminoethylpiperazine (formula ( 5)), 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro (5,5) undecane adduct ((formula 6)), bis (4-aminocyclohexyl) methane ( Formula (7)) etc. are mentioned, However, It is preferable that the compounding quantity of these other alicyclic polyamines is less than 20 mass% among 100 mass% of all the hardening | curing agents (B).

  The curing agent (B) in the present invention is blended with a linear aliphatic polyamine and an aromatic polyamine as other polyamines other than bis (4-amino-3-methylcyclohexyl) methane and norbornanediamine. However, these polyamines are preferably blended in an amount of less than 10% by mass in 100% by mass of the total curing agent (B).

  The epoxy resin (A) used in the present invention is not particularly limited, and any epoxy resin can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type Epoxy resin, resorcinol type epoxy resin, hydroquinone type epoxy resin, catechol type epoxy resin, dihydroxynaphthalene type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, etc. liquid epoxy resin, phenol novolac type epoxy resin, cresol novolac type Epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, phenol aralkyl type epoxy resin Resin, naphthol novolac type epoxy resin, naphthol aralkyl type epoxy resin, naphthol-phenol co-condensed novolac type epoxy resin, naphthol-cresol co-condensed novolac type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenolic resin type epoxy resin, biphenyl modified novolak Type epoxy resin, tetrabromobisphenol A type epoxy resin, brominated phenol novolac type epoxy resin, alicyclic epoxy resin and the like. In addition, the epoxy resin (A) used by this invention may mix | blend the illustrated epoxy resin independently, and may mix and mix multiple types.

In the epoxy resin composition of the present invention, the epoxy equivalent of the epoxy resin (A) is preferably 250 g / eq or less, more preferably 200 g / eq. When the epoxy equivalent is 250 g / eq, the epoxy resin (A) has a low viscosity, and the epoxy resin composition has a low viscosity, so that the reinforcing fibers can be easily impregnated with the resin. In addition, the epoxy equivalent of an epoxy resin (A) can be calculated | required by potentiometric titration using a perchloric acid acetic acid standard solution based on the method of calculating | requiring the epoxy equivalent of JISK7236 (2001) epoxy resin, for example. The average epoxy equivalent in the case of blending a mixture of plural kinds epoxy resin (here, n type) is, n type of formulation weight of the epoxy resin respectively _{ew 1, ew 2, ···,} ew n , And the epoxy equivalent is EEW ₁ , EEW ₂ ,..., EEW _n, and can be calculated by the following formula.

  The epoxy resin composition of the present invention has an initial viscosity in the range of 10 to 1000 mPa · s at 60 ° C., and preferably has a viscosity of 1000 mPa · s or less after being held at 60 ° C. for 15 minutes. The viscosity is more preferably in the range of 50 to 500 mPa · s, and still more preferably in the range of 50 to 300 mPa · s. Here, the initial viscosity means the viscosity after 1 minute has elapsed after mixing and stirring the epoxy resin (A) and the curing agent (B), and the viscosity after holding at 60 ° C. for 15 minutes is 15 after mixing and stirring. The viscosity after a minute has passed. This is because by setting the initial viscosity to 1000 mPa · s or less, the viscosity at the curing temperature can be lowered, the injection time into the reinforcing fiber base is shortened, and the cause of unimpregnation can be prevented. In addition, by setting the initial viscosity to 10 mPa · s or more, the viscosity at the curing temperature does not become too low, and air can be entrained at the time of injection into the reinforcing fiber base to prevent the cause of pits and the impregnation is uneven. This is because the cause of non-impregnation can be prevented. Moreover, when the viscosity after holding at 60 ° C. for 15 minutes exceeds 1000 mPa · s, the FRP obtained using the epoxy resin composition may be unimpregnated.

  In the present invention, the viscosity of the epoxy resin composition is measured, for example, based on a measuring method using a conical constant-speed cone-plate rotational viscometer in JIS Z8803 (1991). Is required. Examples of the measuring device include TVE-30H type manufactured by Toki Sangyo Co., Ltd.

  The epoxy resin composition of the present invention preferably has a curing time of 60 minutes or less at a curing temperature of 60 ° C. Here, the curing time is vulcanized rubber according to JIS K6300-2 (2001) -physical characteristics-part 2: vibrations of 100 times per minute according to the method of obtaining vulcanization characteristics using a vibration vulcanization tester. The 90% vulcanization time tc (90) obtained under the condition of angle ± 1 ° is referred to. If the curing time is within 60 minutes, that is, it means that the productivity is high, and if the curing time exceeds 60 minutes, it means that the productivity is low.

  In the epoxy resin composition of the present invention, the glass transition temperature Tg (° C.) of the cured resin obtained by curing at a curing temperature of 60 ° C. for 1 hour is preferably Tg ≧ 60, more preferably Tg ≧ 70, Preferably, Tg ≧ 80. This is because if the Tg is 60 ° C. or higher, the cured resin and FRP are not deformed during demolding, and a cured product according to the shape of the mold is obtained. In the present invention, the Tg of the resin cured product is a value measured at a rate of temperature increase of 20 ° C./min using a DSC apparatus. More specifically, in the portion showing the step change of the obtained DSC curve, a straight line that is a set of points equidistant in the vertical axis direction from the extended straight line of each baseline, and a step change of the glass transition Let Tg be the temperature at the point where the partial curve intersects. In addition to the DSC apparatus, there are many Tg measurements such as a measurement using thermal expansion by a TMA apparatus and a measurement using viscoelasticity by a DMA apparatus, but the values may differ depending on the measurement principle. Further, in the measurement using the endotherm by the DSC apparatus, there is an influence of the rate of temperature rise, so Tg in the present invention is the value of the above measurement condition. Examples of the measuring device include Pyris1 DSC manufactured by Perkin Elmer.

In the epoxy resin composition of the present invention, the ratio of the epoxy equivalent of the epoxy resin (A) and the active hydrogen equivalent of the curing agent (B) is preferably in the range of 1 / 0.7 to 1 / 1.2, Preferably it is the range of 1 / 0.9-1 / 1.1. This is because when the ratio of the epoxy equivalent to the active hydrogen equivalent is within this range, the cured epoxy resin has excellent heat resistance, mechanical properties, and chemical resistance. In addition, the active hydrogen equivalent of a hardening | curing agent (B) can be calculated | required by remove | dividing the average molecular weight of a polyamine by the number of active hydrogen which has in 1 molecule of polyamine, for example. Moreover, the average active hydrogen equivalent in the case of mixing and mixing multiple types (here n types) of curing agents is the mixing mass of the n types of curing agents aw ₁ , aw ₂ ,. _{When n} and active hydrogen equivalent are AHEW ₁ , AHEW ₂ ,..., AHEW _n , they can be calculated by the following formula.

  The epoxy resin composition of the present invention is most suitable for the RTM method in which the mold temperature from the resin injection to the demolding is kept constant. The present invention can be applied to any molding method using a liquid thermosetting resin such as layup, pultrusion, filament winding, etc., and any molding method is effective in reducing surface irregularities and improving impregnation into reinforcing fibers.

  The epoxy resin composition of the present invention can be suitably used particularly as a matrix resin for fiber-reinforced composite materials. However, due to the low viscosity and low temperature curing characteristics, paints, civil engineering and building materials, adhesives, gel coats are also available. It can also be used for applications such as casting resins and laminates.

  Next, an example of the fiber-reinforced composite material of the present invention obtained using the epoxy resin composition and the reinforcing fiber according to the present invention will be described.

  In the FRP of the present invention, glass fibers, aramid fibers, carbon fibers, boron fibers and the like are suitably used as the reinforcing fibers. Among these, carbon fiber is preferably used because FRP having excellent mechanical properties such as strength and elastic modulus can be obtained while being lightweight.

  The reinforcing fiber may be either a short fiber or a continuous fiber, or both may be used in combination. In order to obtain an FRP having a high fiber volume content (hereinafter sometimes abbreviated as Vf), continuous fibers are preferred.

  In the FRP of the present invention, the reinforcing fiber may be used in the form of a strand, but a reinforcing fiber substrate obtained by processing the reinforcing fiber into a form such as a mat, a woven fabric, a knit, a braid, or a unidirectional sheet is preferably used. Among them, a woven fabric that is easy to obtain a high Vf FRP and excellent in handleability is preferably used.

  The FRP of the present invention is produced by injecting the heated epoxy resin composition into a reinforcing fiber base disposed in a mold heated to a specific temperature, impregnating it, and curing in the mold. It is preferable.

  As the mold, a closed mold made of a rigid body may be used, and a method using a rigid open mold and a flexible film (bag) is also possible. In the latter case, the reinforcing fiber base is placed between the rigid open mold and the flexible film.

  Various types of existing materials such as metals (steel, aluminum, INVAR, etc.), FRP, wood, plaster, etc. are used as the material of the mold made of a rigid body. In addition, as a material for the flexible film, nylon, fluorine resin, silicone resin, or the like is used.

  When a closed mold made of a rigid body is used, it is usually performed by pressurizing and clamping and then injecting and injecting the epoxy resin composition. At this time, it is also possible to provide a suction port separately from the injection port and perform suction by means such as a vacuum pump. It is also possible to perform the suction and inject the epoxy resin only at atmospheric pressure without using any special pressurizing means.

  In the case of using a rigid open mold and a flexible film, the VaRTM method is generally used in which suction is provided, suction is performed by means such as a vacuum pump, and injection by atmospheric pressure is used. It is also possible to adjust the injection pressure to a pressure lower than the atmospheric pressure as in the CAPRI method cited in WO 01/41993. In order to achieve good impregnation by injection at atmospheric pressure or lower, it is effective to use a resin diffusion medium as shown in US Pat. No. 4,902,215.

  The injection pressure of the epoxy resin composition is usually 0.1 to 1.0 MPa, and VaRTM (Vacuum Assist Resin Transfer Molding) method in which the resin composition is injected by vacuum suction inside the mold can be used. And from the point of economical efficiency of equipment, 0.1-0.6 MPa is preferable. Even when pressure injection is performed, it is preferable to suck the inside of the mold in vacuum before injecting the resin composition, because generation of voids is suppressed.

  Since the viscosity characteristics of the epoxy resin composition are sensitive to temperature, it is preferable that both the container and the mold of the epoxy resin composition are kept at a constant temperature in the resin injection step. The temperature of the epoxy resin composition or the container of the epoxy resin and the curing agent is preferably 40 to 70 ° C., more preferably 50 to 60 ° C., and the mold temperature in the injection step, that is, the injection temperature is 40 to 70 ° C. Preferably, it is 50-60 degreeC.

  The epoxy resin composition can be injected into a mold from a single container mixed with all components in a batch, or the epoxy resin and the curing agent can be stored in separate containers via a mixer. It can be injected into the mold or from the container at atmospheric pressure into the mold.

  After resin injection is completed, thermosetting is performed in the mold. Thermosetting in the mold is performed by holding the mold temperature at the time of injection for a certain period of time, raising the temperature to a temperature between the mold temperature at the time of injection and the maximum curing temperature, holding it for a certain time, and then increasing the temperature again. Any of a method of holding and curing for a certain time after reaching the maximum curing temperature and a method of heating to a maximum curing temperature and curing for a certain time can be used. It is preferable that the holding time of the maximum curing temperature in curing in the mold is 0.5 to 1 hour.

  After demolding, after-curing can be performed at a temperature higher than the maximum curing temperature in the mold. In this case, the curing in the mold becomes a precure. The after-curing time is preferably 0.5 to 12 hours, more preferably 1 to 4 hours.

  The pre-curing method at 50 ° C. to 70 ° C. is economically advantageous because inexpensive materials can be used for the mold material, auxiliary material, and heat source.

  In addition, in the FRP manufacturing method, an FRP to be obtained is obtained by using a mold having a plurality of injection ports, and injecting an epoxy resin composition from a plurality of injection ports simultaneously or sequentially with a time difference. It is preferable to select an appropriate condition according to the reason that a degree of freedom corresponding to molded bodies of various shapes and sizes can be obtained. The number and shape of such injection ports are not limited, but in order to enable injection in a short time, it is better that there are more injection ports, and the arrangement is a position where the flow length of the resin can be shortened according to the shape of the molded product. Is preferred.

  When the FRP of the present invention is used on a design surface such as an automobile outer plate, the surface unevenness is preferably 0.6 μm or less, more preferably 0.5 μm or less. The surface unevenness is measured according to JIS B0601 (1994), and the surface unevenness of the FRP is measured, and the surface unevenness is represented by Ry, which matches the appearance quality of the FRP. An example of the measuring apparatus is a surf coder SE3400 manufactured by Kosaka Laboratory.

  Since the FRP according to the present invention is lightweight and has excellent mechanical properties such as strength and elastic modulus, it is preferably used for structural members and outer panels of airplanes, space satellites, industrial machines, railway vehicles, ships, automobiles, and the like. Moreover, since it is excellent also in surface quality, it is preferably used especially for an automobile outer plate.

  Hereinafter, specific configurations of the epoxy resin composition of the present invention and a fiber-reinforced composite material using the epoxy resin composition will be described based on examples. In addition, each component used by each epoxy resin composition of an Example and a comparative example is as showing with the following abbreviation.

A. Resin raw materials The following resin raw materials were applied.
1. Epoxy resin (A)
(1) “jER (registered trademark)” 828: manufactured by Japan Epoxy Resin, bisphenol A type epoxy resin, epoxy equivalent of 184 to 194 g / eq
(2) “jER (registered trademark)” 1004: manufactured by Japan Epoxy Resin, bisphenol A type epoxy resin, epoxy equivalent of 875-975 g / eq
(3) “jER (registered trademark)” 1001: manufactured by Japan Epoxy Resin, bisphenol A type epoxy resin, epoxy equivalent 450-500 g / eq
2. Curing agent (B)
(4) “Ancamine” (registered trademark) 2049: manufactured by Air Products & Chemicals, bis (4-amino-3-methylcyclohexyl) methane, active hydrogen equivalent 60 g / eq
(5) “NBDA” (registered trademark): manufactured by Mitsui Chemicals, norbornanediamine, active hydrogen equivalent: 38.5 g / eq
(6) “Amicure” (registered trademark) PACM: manufactured by Air Products and Chemicals, bis (4-aminocyclohexyl) methane, active hydrogen equivalent: 52.5 g / eq
(7) IPDA: manufactured by PTI Japan, isophoronediamine, active hydrogen equivalent: 43 g / eq
(8) “Curazole” (registered trademark) 2MZ: manufactured by Shikoku Kasei Co., Ltd., 2-methylimidazole (9) glycerin: manufactured by Wako Pure Chemical Industries, Ltd.

B. Preparation of epoxy resin composition The epoxy resin (A) and the curing agent (B) were mixed and stirred as shown in Tables 1 to 3 to prepare an epoxy resin composition. In addition, the number in a table | surface shows the mass part of the mix | blended component.

C. Viscosity measurement of resin composition The initial viscosity of the epoxy resin composition and the viscosity after 10 minutes were measured in accordance with a measuring method using a cone-and-speed cone-plate rotational viscometer in JIS Z8803 (1991). Here, TVE-30H type manufactured by Toki Sangyo Co., Ltd. was used, and the rotor was 1 ° 34 ′ × R24 and the sample amount was 1 cm ³ .

D. Measurement of curing time The curing time of the epoxy resin composition obtained by the method B was measured by the following method. Unvulcanized rubber in JIS K6300-2 (2001)-Physical characteristics-Part 2: According to the method of obtaining vulcanization characteristics using a vibration vulcanization tester, the vibration frequency is 100 times per minute and the vibration angle is ± 1 °. The 90% vulcanization time tc (90) was taken as the curing time. Here, a Curalastometer type V manufactured by Orientec was used.

E. Preparation of cured resin product The epoxy resin composition obtained by the method B was poured into a mold having a plate-like cavity having a thickness of 2 mm, and the oven was used at 60 ° C. for 1 hour, and shown in Tables 1 and 3 Each was cured under two conditions of curing time to obtain a plate-shaped resin cured product having a thickness of 2 mm.

F. Glass transition temperature Tg
About the resin cured material board obtained by the method of said E, glass transition temperature Tg was measured by DSC method based on JISK7121 (1987). Here, Pyris 1 DSC of DSC manufactured by Perkin Elmer was used, and the temperature rising rate was 20 ° C./min.

G. Production of FRP FRP was produced by the RTM molding method. As the mold, a mold composed of an upper mold and a lower mold having a plate-like cavity having a length of 1000 mm × width of 1000 mm × height of 1.2 mm was used. As a preform, a carbon fiber fabric “Torayca” cloth BT70-30 (carbon fiber: T700-12K, woven structure: plain weave, basis weight: 300 g / m ² ) manufactured by Toray as a reinforcing fiber base material is laminated. Using.

  First, a preform was set in a mold cavity and clamped. Next, after the pressure inside the mold maintained at a predetermined temperature was reduced to 0.1 mmHg or less, the epoxy resin composition was injected and impregnated into the preform. When the resin flowed out from the suction port, the resin injection port and then the suction port were closed, and the resin composition was cured for the curing times shown in Tables 1 to 3 to obtain a flat plate-like FRP.

H. Surface unevenness of FRP For the flat plate-like FRP obtained by the method G, the surface unevenness of FRP was measured in accordance with JIS B0601 (1994), and the surface unevenness was expressed by Ry. Here, a surf coder SE3400 manufactured by Kosaka Laboratory was used. The measurement conditions were a measurement distance of 10 mm and a measurement speed of 2 mm / min. An arbitrary value on the FRP surface was measured to calculate an average value.

Example 1
As an example of the epoxy resin composition of the present invention, an epoxy resin composition containing 70% by mass of bis (4-amino-3-methylcyclohexyl) methane and 30% by mass of norbornanediamine with respect to 100% by mass of the total curing agent. Were adjusted as shown in Table 1, and a cured epoxy resin and FRP were obtained at a curing temperature of 60 ° C.

Example 2
As an example of the epoxy resin composition of the present invention, an epoxy resin composition containing 50% by mass of bis (4-amino-3-methylcyclohexyl) methane and 50% by mass of norbornanediamine with respect to 100% by mass of the total curing agent. Were adjusted as shown in Table 1, and a cured epoxy resin and FRP were obtained at a curing temperature of 60 ° C.

Example 3
As an example of the epoxy resin composition of the present invention, an epoxy resin composition containing 30% by mass of bis (4-amino-3-methylcyclohexyl) methane and 70% by mass of norbornanediamine with respect to 100% by mass of the total curing agent. The product was prepared as shown in Table 1, and an epoxy resin cured product and FRP were obtained at a curing temperature of 60 ° C.

  As shown in Table 1, the epoxy resin compositions of Examples 1 to 3 have a small increase in viscosity at 60 ° C. and can be cured within 60 minutes. Further, the surface roughness of the obtained FRP was 0.6 μm, and the surface design was excellent.

Comparative Example 1
As an example other than the epoxy resin composition of the present invention, as shown in Table 1, an epoxy resin composition containing 100% by mass of bis (4-amino-3-methylcyclohexyl) methane with respect to 100% by mass of the total curing agent. The cured epoxy resin and FRP were obtained at a curing temperature of 60 ° C.

  As shown in Table 1, the resin composition of this comparative example required 287 minutes for curing at 60 ° C., and the productivity of FRP was low.

Comparative Example 2
As an example other than the epoxy resin composition of the present invention, an epoxy resin composition containing 100% by mass of norbornanediamine with respect to 100% by mass of the total curing agent was prepared as shown in Table 1, and the epoxy resin was cured at a curing temperature of 60 ° C. A cured product and FRP were obtained.

  As shown in Table 1, the resin composition of this comparative example had a high viscosity of 1680 mPa · s after 10 minutes at 60 ° C., and an unimpregnated part was generated in a part of the obtained FRP.

Comparative Example 3
As an example other than the epoxy resin composition of the present invention, an epoxy resin composition containing 100% by mass of bis (4-amino-cyclohexyl) methane is prepared as shown in Table 1 with respect to 100% by mass of the total curing agent, An epoxy resin cured product and FRP were obtained at a curing temperature of 60 ° C.

  As shown in Table 1, the resin composition of this comparative example required 75 minutes for curing at 60 ° C., and the productivity of FRP was low.

Comparative Example 4
As an example other than the epoxy resin composition of the present invention, an epoxy resin composition containing 100% by mass of isophoronediamine is prepared as shown in Table 1 with respect to 100% by mass of the total curing agent, and epoxy is cured at a curing temperature of 60 ° C. A cured resin and FRP were obtained.

  As shown in Table 1, the resin composition of Comparative Example 4 had a viscosity of 5400 mPa · s after 10 minutes at 60 ° C., and an unimpregnated portion was generated in the obtained FRP.

Comparative Example 5
As an example other than the epoxy resin composition of the present invention, an epoxy resin composition containing 50% by mass of norbornanediamine and 50% by mass of bis (4-amino-cyclohexyl) methane with respect to 100% by mass of the total curing agent is shown. 1 was prepared, and a cured epoxy resin and FRP were obtained at a curing temperature of 60 ° C.

  As shown in Table 1, the resin composition of Comparative Example 4 had a high viscosity of 1380 mPa · s after 10 minutes at 60 ° C., and an unimpregnated portion was generated in the obtained FRP.

Comparative Example 6
As an epoxy resin composition curable at 100 ° C. for 10 minutes, an epoxy resin composition described in Example 1 of WO 02/081540, that is, an epoxy resin composition prepared as shown in Table 2 was used. The cured epoxy resin and FRP were obtained under the curing conditions of 100 ° C. for 10 minutes. The surface roughness of the FRP obtained as shown in Table 2 was 1.2 μm, which was poor in surface design.

Reference example 1
As an example of the epoxy resin composition of the present invention, an epoxy resin composition containing 50% by mass of bis (4-amino-3-methylcyclohexyl) methane and 50% by mass of norbornanediamine with respect to 100% by mass of the total curing agent. Were adjusted as shown in Table 3, and a cured epoxy resin and FRP were obtained at a curing temperature of 60 ° C.

  As shown in Table 3, since the epoxy resin composition of the present example has an epoxy equivalent of 277.2 g / eq, the initial viscosity at 60 ° C. and the viscosity after 10 minutes are high. Although the surface roughness of the obtained FRP was 0.6 μm, the design was excellent.

Reference example 2
As an example of the epoxy resin composition of the present invention, an epoxy resin composition containing 50% by mass of bis (4-amino-3-methylcyclohexyl) methane and 50% by mass of norbornanediamine with respect to 100% by mass of the total curing agent. Were adjusted as shown in Table 3, and a cured epoxy resin and FRP were obtained at a curing temperature of 60 ° C.

  As shown in Table 3, since the epoxy resin composition of this example has an epoxy equivalent of 249.0 g / eq, the initial viscosity at 60 ° C. and the viscosity after 10 minutes are high. Although some unimpregnated parts were generated, the surface roughness of the obtained FRP was 0.6 μm, which was excellent in design.

Reference example 3
As an example of the epoxy resin composition of the present invention, an epoxy resin composition containing 90% by mass of bis (4-amino-3-methylcyclohexyl) methane and 10% by mass of norbornanediamine with respect to 100% by mass of the total curing agent. Were adjusted as shown in Table 3, and a cured epoxy resin and FRP were obtained at a curing temperature of 60 ° C.

  As shown in Table 3, although the epoxy resin composition of this example required 150 minutes for curing at 60 ° C., the surface roughness of the obtained FRP was 0.6 μm, which was excellent in surface design.

  The epoxy resin composition of the present invention is excellent in resin impregnation due to a small increase in viscosity at a relatively low temperature of 60 ° C. or lower, and becomes a cured product that can be removed in a short time within 1 hour. Suitable for molding excellent fiber-reinforced composite materials. Also, fiber-reinforced composite materials with excellent surface design can be obtained by the RTM molding method, etc., and can be applied to many parts such as industrial machines, railway vehicles, ships and automobiles. It is suitable for application to.

Claims (6)

An epoxy resin composition comprising at least an epoxy resin (A) and a curing agent (B), wherein the curing agent (B) is bis (4-amino-3-methylcyclohexyl) relative to 100% by mass of the total curing agent. ) An epoxy resin composition comprising 30 to 90% by mass of methane and 70 to 10% by mass of norbornanediamine. The epoxy resin composition of Claim 1 whose epoxy equivalent of an epoxy resin (A) is 250 g / eq or less. The epoxy resin composition of Claim 1 or 2 whose initial viscosity in 60 degreeC is 10-1000 mPa * s. The epoxy resin composition according to claim 1, wherein the cured resin obtained by curing at 60 ° C. for 1 hour has a glass transition temperature Tg (° C.) of 60 ° C. or higher. A fiber-reinforced composite material comprising a cured resin obtained by curing the epoxy resin composition according to claim 1 and a reinforcing fiber. The fiber-reinforced composite material according to claim 5, wherein the surface unevenness (Ry) is 0.6 μm or less.