JP2000281747A - Epoxy resin composition for composite materials - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition which does not show excessive tack when used in the production of prepregs and gives prepregs excellent in storage stability and fabricability and capable of giving a molding excellent in heat resistance by incorporating a specified amount of diaminodiphenyl sulfone in an epoxy resin mixture. SOLUTION: This composition is prepared by incorporating 20-45 pts.wt. diaminodiphenyl sulfone in 100 pts.wt. epoxy resin mixture comprising 20-50 pts.wt. bisphenol A and/or bisphenol F epoxy resins, 10-30 pts.wt. tetrafunctional glycidylamine epoxy resin, and 3-15 pts.wt. phenoxy resin. The epoxy resin mixture may additionally contain a phenol novolac epoxy resin, usually, in an amount of at most 35 pts.wt. per 100 pts.wt. epoxy resin mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for a composite material, and more particularly to an epoxy resin composition for a composite material suitable for use in printing ink rolls, bicycle pipes, pressure vessels, and the like.

[0002]

2. Description of the Related Art Combined materials using carbon fiber, glass fiber, etc. as reinforcing material are used as industrial materials for golf shafts, fishing rods, sports and leisure goods such as tennis rackets, aircraft, printing ink rolls, pressure vessels and the like. In addition, it is widely used as one of the materials in the medical field and the construction and civil engineering field. In recent years, there are many cases in which such a combined material is used for manufacturing industrial material parts.
Composite materials such as reinforced fiber plastics (FRP) and carbon fiber reinforced plastics (CFRP) are made by impregnating reinforced fibers such as carbon fiber, glass fiber, aramid fiber, and boron fiber with a matrix resin to form a prepreg, and then laminating them. And then cured at a suitable temperature. As a matrix resin of CFRP, an epoxy resin having excellent adhesion to carbon fibers is employed. However, bisphenol A type epoxy resins, which are conventionally widely used as this type of epoxy resin, are inferior in heat resistance and have poor composite physical properties, especially lamination shear strength (I).
LSS). On the other hand, polyfunctional epoxy resins have excellent heat resistance but high reactivity, so it is necessary to worry about safety when blending with other components, and keep the quality of the obtained resin composition constant. There is a problem that it is difficult. In addition, when the main component of the resin composition is a polyfunctional epoxy resin, the tackiness of a prepreg or the like obtained by impregnating this with a reinforcing fiber makes it difficult to handle and impairs workability. is there. And, when heated to mold this prepreg, the viscosity of the resin composition during heating is extremely low, so that the prepreg is easily shaken or leaked in the mold, or the resin is likely to leak.
Due to this, there is an inconvenience that it is difficult to obtain a molded body with high accuracy. In order to control the viscosity during molding, it is possible to use diaminodiphenyl sulfone and dicyandiamide in combination as a curing agent for an epoxy resin, and to further add a curing accelerator to the resin composition, as disclosed in JP-A-59-207920.
However, this method has a disadvantage that the moisture resistance of the prepreg is impaired. Furthermore, a prepreg obtained by using a conventional epoxy resin composition has a disadvantage that delamination or cracks are generated in a molded product because curing distortion occurs during molding. It is thought that one of the causes of curing distortion is that the amount of low molecular weight epoxy resin in the resin composition is excessive, but instead of low molecular weight epoxy resin, bisphenol type epoxy resin that is solid at room temperature is used. In this case, there is a problem that the glass transition point of the cured product decreases. Epoxy resin compositions have recently been used in the field of printing rolls, and rubber-coated CFRs have been used.
A roll made of P is an example. This type of printing roll is C
An unvulcanized rubber is wound around an FRP tube and vulcanized under steam heating at 150 ° C.
A conventional CFRP tube using an epoxy resin that is cured by heat has a problem that deformation, expansion, and peeling are caused by steam heating at the time of vulcanization.

[0003]

DISCLOSURE OF THE INVENTION In order to solve the above-mentioned various problems, the present invention does not exhibit excessive tackiness in the production of prepreg, and furthermore, the obtained prepreg has a storage stability and Provided is an epoxy resin composition for a composite material which is excellent in moldability and can obtain a molded article excellent in heat resistance and moisture resistance from the prepreg.

[0004]

The epoxy resin composition for a composite material according to the present invention comprises 20 to 50 parts by weight of a bisphenol A epoxy resin and / or bisphenol F type epoxy resin, and 10 to 30 parts by weight of 4 For 100 parts by weight of an epoxy-based mixture containing a functional glycidylamine-type epoxy resin, 15 to 40 parts by weight of an epoxy resin having an oxazolidone ring, and 3 to 15 parts by weight of a phenoxy resin, 20 to 45 parts of diaminodiphenyl sulfone are added. It is blended by weight. The above epoxy resin-based mixture has 35
It may further contain phenol novolak type epoxy resin of not more than part by weight.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the epoxy resin composition for a composite material of the present invention, the amount of diaminodiphenyl sulfone as a curing agent is determined based on 100 parts by weight of an epoxy-based mixture. A bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin (component (A)), a tetrafunctional glycidylamine type epoxy resin (component (B)), and an epoxy resin having an oxazolidone ring (component (C)). , A phenoxy resin (component (D)) as an essential component, and the content of each component is 2 (A).
0 to 50 parts by weight, preferably 35 to 48 parts by weight, component (B) 10 to 30 parts by weight, preferably 15 to 25 parts by weight,
Component (C) is 15 to 40 parts by weight, preferably component (D) is 3 to 40 parts by weight.
It is in the range of 15 parts by weight. The above epoxy-based mixture 10
If the amount of the component (A) contained per 0 parts by weight is less than 20 parts by weight, the viscosity of the mixture becomes high and impregnation into a fiber bundle such as carbon fiber becomes difficult. It is preferable to mix a phenol novolak type epoxy resin with a phenol novolak type epoxy resin having a small molecular weight. When the amount of the component (A) exceeds 55 parts by weight, it is difficult to adjust the viscosity of the mixture, and it is difficult to produce an appropriate prepreg. Further, the glass transition temperature of the cured product is lowered, and the heat resistance is lowered. When the amount of the component (B) is less than 10 parts by weight per 100 parts by weight of the epoxy-based mixture, the glass transition temperature when the mixture is cured cannot be maintained in a high temperature range, and when the amount exceeds 30 parts by weight. The storage stability and moisture resistance of the prepreg deteriorate. When the amount of the component (C) is less than 15 parts by weight per 100 parts by weight of the epoxy-based mixture, peeling is likely to occur when the prepreg is processed into a molded article.
If the amount exceeds 5 parts by weight, the viscosity of the mixture increases, which hinders impregnation into carbon fibers, and also lowers the glass transition temperature of the cured product. When the amount of the component (D) is less than 3 parts by weight per 100 parts by weight of the epoxy-based mixture,
Not only is it difficult to adjust the viscosity of the mixture, but also the viscosity at the time of curing the mixture decreases. For this reason, the prepreg is liable to cause resin leakage, and in addition, the tack and drape are easily weakened, and the molding operation becomes difficult. If the amount exceeds 15 parts by weight, the viscosity of the mixture becomes too high, so that impregnation into carbon fibers or the like becomes difficult, and there is a possibility that a satisfactory prepreg cannot be produced.

Bisphenol A as the component (A) of the present invention
The epoxy resin is a condensation reaction product of bisphenol A and epichlorohydrin, and the bisphenol F epoxy resin is a condensation reaction product of bisphenol F and epichlorohydrin. The bisphenol A type epoxy resin used in the present invention has an epoxy equivalent of 170-1.
90 and a viscosity at 25 ° C. of 9.0 to 15
It is preferably in the range of poise. This type of bisphenol A epoxy resin includes commercially available products such as Epicoat 828 (manufactured by Yuka Shell Epoxy), Epototo YD128 (manufactured by Toto Kasei), and Epicron 840 (manufactured by Dainippon Ink and Chemicals, Inc.). . The bisphenol F type epoxy resin used in the present invention has an epoxy equivalent of 1
The viscosity at 25 ° C. is in the range of 55 to 190.
It is preferably in the range of 0 to 4.5 poise. This type of bisphenol F type epoxy resin has Epicoat 8
07 (made by Yuka Shell Epoxy), Epotote YDF1
Commercial products such as No. 70 (manufactured by Toto Kasei) and Epicron 830 (manufactured by Dainippon Ink and Chemicals, Inc.) are included. Of the present invention
The tetrafunctional glycidylamine type epoxy resin as the component (B) is a condensation reaction product of diaminodiphenylmethane and epichlorohydrin, and is represented by the following general formula.

Embedded image The above-mentioned tetrafunctional glycidylamine type epoxy resin preferably has an epoxy equivalent in the range of 110 to 135 and a viscosity at 50 ° C of 4.0 to 18 poise. Examples of commercially available products include Epototo YH434 (manufactured by Toto Kasei), Epototo YH434L (manufactured by Toto Kasei), Sumiepoxy ELM434, Sumiepoxy ELM
434HV (all manufactured by Sumitomo Chemical Co., Ltd.), Epicoat 60
4 (made by Yuka Shell Epoxy), Araldite MY72
0 (made by Ciba-Geigy). The epoxy resin having an oxazolidone ring as the component (C) of the present invention can be obtained, for example, by reacting a bisphenol A type epoxy resin with diphenylmethane-4,4′-diisocyanate. It can be represented by an equation.

Embedded image In preparing the epoxy resin of the component (C), the diphenylmethane-
In addition to 4,4′-diisocyanate, hexamethylene diisocyanate, isoboron diisocyanate, tolylene diisocyanate, xylene diisocyanate,
3-bis (isocyanatomethyl) cyclohexane and the like can be used. The epoxy resin of the component (C) preferably has an epoxy equivalent in the range of 330 to 500. This type of epoxy resin includes XAC4151, XA
C4152 (from Asahi Ciba), Tactics 740,
Commercial products such as Tactics 741 (both manufactured by Dow Chemical Company) are included. The phenoxy resin as the component (D) of the present invention is a thermoplastic resin composed of polyhydroxyether derived from bisphenol A and epichlorohydrin, and is represented by the following general formula.

Embedded image The phenoxy resin used in the present invention usually has a number average molecular weight in a range of 10,000 to 28,000 and a weight average molecular weight in a range of 60,000 to 118,000 by GPC analysis. Commercially available products include Phenothote YP-5
0, phenothoto YP-70 (manufactured by Toto Kasei Co., Ltd.), Epicoat OL-53 (manufactured by Yuka Shell Epoxy), Sumiepoxy ESP-50 (manufactured by Sumitomo Chemical Co., Ltd.) and the like.

The epoxy mixture referred to in the present invention may contain other resin components as required, but the resin component is preferably a phenol novolak type epoxy resin (component (E)). The epoxy resin of the component (E) can be represented by the following general formula, the epoxy equivalent thereof is in the range of 170 to 190, and the viscosity at 52 ° C. is 3
It is in the range of 5 to 65 poise.

Embedded image This kind of phenol novolak type epoxy resin includes Epicoat 152, Epicoat 154 (all manufactured by Yuka Shell Epoxy), Epototo YDPN638, Epototo Y
DPN601, Epotote YDP. It is commercially available under the names of N602 (above, manufactured by Toto Kasei Co., Ltd.), Dow Epoxy DEN431, Dow Epoxy DEN438, Dow Epoxy DEN439 (below, manufactured by Dow Chemical Company), Araldite EPN1138 (manufactured by Ciba Geigy). When the above-mentioned component (E) is blended with the epoxy-based mixture of the present invention, the blending amount is in the range of 35 parts by weight or less, preferably 25 parts by weight or less per 100 parts by weight of the epoxy-based mixture. If the amount of the component (E) exceeds 35 parts by weight, the epoxy-based mixture thickens, making it difficult to impregnate carbon fibers and the like.

[0008] In the resin composition for a composite material of the present invention,
Diaminodiphenyl sulfone used as a curing agent includes 4,4′-diaminodiphenyl sulfone and 3,4′-diaminodiphenyl sulfone.
Any of 3′-diaminodiphenyl sulfone may be used, and a mixture thereof may be used. Diaminodiphenyl sulfone is in powder form at room temperature. The diaminodiphenyl sulfone used in the present invention has an upper limit of particle size of 2
0 μm or less, preferably 17 μm or less, more preferably 12 μm or less, and the lower limit of the particle size is 0.01 μm or more,
Preferably, the powder particles having a particle size distribution of 0.1 μm or more, more preferably 1 μm or more occupy 65% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more of all the powder particles. Is desirable.

The epoxy resin composition for a composite material of the present invention may contain an epoxy resin, a toughness-imparting agent, a filler, a colorant, etc. other than those described above as long as the performance is not impaired. Examples of such epoxy resins include bisphenol A-type epoxy resins other than the component (A), such as bisphenol A-type epoxy resins which are semi-solid or solid at ordinary temperature, o-cresol novolak-type ethoxy resins, and cycloaliphatic ethoxy resins. , Triglycidylmethane type epoxy resin, trifunctional glycidylamine type epoxy resin, halogenated bisphenol A type epoxy resin, and the like. Examples of the toughness imparting agent include a reactive elastomer, a Hiker CTBN-modified epoxy resin, a urethane-modified epoxy resin, an epoxy resin with nitrile rubber, an epoxy resin with crosslinked acrylic rubber fine particles, a silicone-modified epoxy resin, and an epoxy resin with a thermoplastic elastomer. . As the filler, inorganic fine particles, for example, mica, alumina, talc, finely divided silica, wollastonite, sepiolite, basic magnesium sulfate, zinc powder, aluminum powder, organic fine particles, for example, acrylic fine particles, epoxy resin fine particles, polyurethane Fine particles and the like can be used. Examples of the coloring agent include azo pigments, phthalocyanine-based pigments, quinacridone-based pigments, and anthraquinone-based pigments as organic pigments, and titanium dioxide, graphite, cobalt violet, and red iron oxide as inorganic pigments.
The epoxy resin composition for a composite material of the present invention may contain a curing agent or a curing accelerator other than diaminodiphenylsulfone as required.
Examples of the curing agent include diaminodiphenylsulfone and diaminodiethylbenzene, and examples of the curing accelerator include boron trifluoride monoethylamine complex and boron trichloride monoethylamine complex.

The epoxy resin composition for a composite material of the present invention can be prepared by any method. However, (A)
To the mixture of the component, the component (C) and the component (D), preferably, the component (E) is added, and the mixture is heated and mixed at 200 ° C. without cooling, and then cooled to 120 ° C. or less by active cooling or natural heat radiation, and then ( The method of adding the tetrafunctional glycidylamine type epoxy resin as the component (B) and lowering the temperature of the mixture to 90 ° C. or lower, and then adding diaminodiphenyl sulfone as a curing agent is preferably used. When adding diaminodiphenyl sulfone, it is preferable to perform vacuum degassing while stirring to prevent entrapment of voids in the prepreg. According to this method, diaminodiphenyl sulfone can be uniformly dispersed in the resin composition, and a composition having excellent storage stability can be obtained. When diaminodiphenyl sulfone is added and mixed in a state where the temperature of the epoxy-based mixture is higher than 90 ° C., a part of the resin is dissolved in the epoxy resin and reacts, so that the resin composition is impregnated into the reinforcing fiber base material. The storage stability of the prepreg thus obtained is significantly impaired.

The prepreg can be obtained by impregnating the reinforcing fiber with the epoxy resin composition for a composite material of the present invention. There are no particular restrictions on the reinforcing fibers, and any fibers used as reinforcing fibers in composite materials can be used. For example, carbon fiber, glass fiber,
Aramid fibers, boron fibers, silicon carbide fibers, and surface-treated organic fibers can be arbitrarily used. Two or more types of reinforcing fibers can be used. In particular, a carbon fiber is preferred as the reinforcing fiber because a lightweight and highly rigid molded product can be obtained. The form of the prepreg is not particularly limited, and an arbitrary form such as a unidirectional material, a woven fabric, a braided woven fabric, or a nonwoven fabric can be appropriately selected according to the purpose.

When impregnating the reinforcing fiber with the resin composition of the present invention, the impregnation method is not particularly limited. However, a so-called hot melt method, in which the resin composition is usually heated to 60 to 90 ° C. to impregnate the reinforcing fibers, is preferably employed. The content of the resin composition in the prepreg thus produced is usually 25 to 50% by weight, preferably 30 to 45% by weight based on the total amount of the reinforcing fibers and the resin composition. The prepreg is ultimately formed into a consolidated material. For example, prepregs are laminated, and usually at 150 to 200 ° C. in an autoclave or a pressure press.
The cured material can be obtained by heat-curing for a period of minutes to 3 hours. The resulting composite material has features of uniform and stable quality and few voids, despite the fact that diaminodiphenyl sulfone used as a curing agent is a dispersion (solid). The composite material obtained by using the resin composition of the present invention is, for example, a roll for printing ink,
CFRP that can be used for bicycle pipes, pressure vessels, etc.
Suitable for making drums. Incidentally, the CFRP drum using the resin composition of the present invention is excellent not only in heat resistance at 150 ° C., but also less affected by steam, and thus has excellent dimensional accuracy.

[0013]

The epoxy resin composition for a composite material of the present invention has safety at the time of preparation which cannot be expected from a conventional epoxy resin composition, and can sufficiently remove bubbles in the composition by vacuum degassing. it can. The prepreg obtained by impregnating the epoxy resin composition into a reinforcing fiber has good moisture resistance and storage stability, is excellent in moldability into pipes and the like, and the composite material obtained from the prepreg has few voids and is excellent. It has excellent water resistance and does not cause delamination or cracks.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Example 1 (A) Bisphenol F type epoxy resin 22 parts by weight [Epototo YDF170 (Toto Kasei)] (B) Tetrafunctional glycidylamine type epoxy resin 18 parts by weight [Epotote YH434L (Toto Kasei)] (C) 34 parts by weight of epoxy resin having an oxazolidone ring [XAC4152 (manufactured by Asahi Ciba)] (D) 4 parts by weight of phenoxy resin [Phenototo YP-70 (manufactured by Toto Kasei)] (E) 22 parts by weight of phenol novolak type epoxy resin [ YDPN 638 (manufactured by Toto Kasei)] The above components (A), (C), (D) and (E)
After mixing and melting at 2 ° C for 2 hours, the temperature was lowered to 120 ° C,
The component (B) was added and mixed. After further lowering the temperature of this mixture, 25 parts by weight of diaminodiphenyl sulfone [pulverized product of Seika Cure S (manufactured by Wakayama Seika Kogyo)] as a curing agent was added, and vacuum degassing was continued for 20 minutes, followed by epoxy for composite material. A resin composition was obtained. Example 2 (A) Bisphenol A type epoxy resin 46 parts by weight [Epicoat EP828 (made by Yuka Shell Epoxy)] (B) Tetrafunctional glycidylamine type epoxy resin 23 parts by weight [Epotote YH434L (made by Toto Kasei)] ( C) 20 parts by weight of an epoxy resin having an oxazolidone ring [XAC4152 (manufactured by Asahi Ciba)] (D) 11 parts by weight of a phenoxy resin [phenototo YP-70 (manufactured by Toto Kasei)] The component (A) and the component (C) After the components and the component (D) were mixed and dissolved at 170 ° C. for 2 hours, the temperature was lowered to 120 ° C., and the component (B) was added and mixed. Next, after further lowering the temperature of the mixture, 25 parts by weight of diaminodiphenyl sulfone [Seika Cure S ground product (manufactured by Wakayama Seika Kogyo Co., Ltd.)] as a curing agent was added, and vacuum deaeration was continued for 20 minutes to prepare a composite material. An epoxy resin composition was obtained. Comparative Example 1 (B) Tetrafunctional glycidylamine type epoxy resin 50 parts by weight [Epototo YH434L (Toto Kasei)] (E) Phenol novolak type epoxy resin 50 parts by weight [Epotote YDPN638 (Toto Kasei)] After uniformly mixing the component (B) and the component (E) at 85 ° C., 44 parts by weight of diaminodiphenylsulfone are added as a curing agent, and 1.5 parts by weight of a diethylamine complex of boron trichloride is further added as a curing accelerator. Then, the mixture was sufficiently stirred and mixed to obtain an epoxy resin composition. Production of prepreg and composite material using the prepreg and evaluation thereof The epoxy resin compositions obtained in the above Examples and Comparative Examples were each subjected to a tensile modulus of 235 GPa and a tensile strength of 3.
The carbon fiber of 53 GPa was impregnated to produce a unidirectional prepreg (Vf: 60 vo1%). Each unidirectional prepreg obtained by using the epoxy resin compositions obtained in Examples 1 and 2 showed little change in tack and drape even after being left at room temperature for one week, so that handling during lamination was good. However, the one-way prepreg obtained by using the epoxy resin composition of Comparative Example 1 had too high tack and was extremely poor in handling during lamination, and the one-way prepreg that had been left at room temperature for one week was hardened and the pipe was hardened. The more difficult to wind, the lower the drapability. Further, a composite material is manufactured using each of the above prepregs, and each composite material is cut into a length of 3 using a cutting machine.
It was cut to 0 cm and 15 cm in width to produce a CFRP plate.
When the cross section of each molded product was observed with a scanning electron microscope,
The molded articles using the epoxy resin compositions of Example 1 and Example 2 hardly generated voids, but the molded articles using the epoxy resin composition of Comparative Example 1 had a large number of voids. It was recognized that a void had occurred. Furthermore, each of the above composite materials is cut to a length of 60 mm,
A test piece having a width of 10 mm and a thickness of 1.5 mm was obtained. When each test piece was left in steam at 150 ° C. for 40 hours, the weight increase of the composite materials using the epoxy resin compositions of Examples 1 and 2 was 5.6% by weight and 5.5% by weight, respectively. In contrast, that of the composite material using the epoxy resin of Comparative Example 1 was 7.5% by weight, and swelling was observed on the surface, and delamination and cracks were observed.

Claims (2)

[Claims] 1. 20 to 50 parts by weight of (A) bisphenol A type epoxy resin and / or bisphenol F type epoxy resin, 10 to 30 parts by weight of (B) tetrafunctional glycidylamine type epoxy resin, and 15 to 40 parts by weight. Parts by weight (C)
An epoxy resin composition for a composite material in which 20 to 45 parts by weight of diaminodiphenyl sulfone is mixed with 100 parts by weight of an epoxy-based mixture containing an epoxy resin having an oxazolidone ring and 3 to 15 parts by weight of (D) phenoxy resin. . 2. The epoxy resin composition for a composite material according to claim 1, wherein the epoxy-based mixture further contains 35 parts by weight or less of (E) a phenol novolak type epoxy resin.