JP2012025892A - Resin composition, prepreg using the same, and fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition hardly generating yellowing or white spot even if being exposed to light, and to provide a prepreg using the resin composition, and a fiber-reinforced composite material.SOLUTION: An epoxy resin composition contains a hydrogenated bisphenol type A epoxy resin (A), an epoxy resin (B) having a skeleton shown by structural formula (I), and a curing agent (C) comprising dicyandiamide and/or boron halide complex. A resin film and a prepreg using the resin composition, and the fiber-reinforced composite material using the prepreg are also provided.

Description

  The present invention relates to a resin composition having excellent weather resistance, a prepreg using the resin composition as a matrix resin, and a fiber-reinforced composite material.

Fiber reinforced composite materials are widely used from sports / leisure applications to industrial applications such as automobiles and aircrafts, taking advantage of their light weight, high strength and high rigidity. Particularly in recent years, carbon fiber reinforced composite materials that are lighter and have higher strength and rigidity have been increasingly used for industrial applications.
The carbon fiber composite material molding method uses a prepreg in which resin is pre-impregnated with straightly aligned carbon fibers as an intermediate material in order to prevent strength reduction due to fiber bending during molding. A method of curing with an oven or a press is common.
The carbon fiber composite material is not only used as a structural member by taking advantage of its characteristics, but also may be used as a design by arranging a woven fabric on the surface. In that case, a transparent surface treatment such as clear coating is often used.

  In the carbon fiber reinforced composite material, an epoxy resin having excellent strength when used as a composite material as a matrix resin is generally used. However, bisphenol-type epoxy resins that are often used as general-purpose resins are susceptible to yellowing and vitiligo due to exposure to sunlight due to their aromatic ring skeleton, making them suitable for using carbon fiber reinforced composite materials as design parts. There was no case. Therefore, Patent Document 1 proposes a resin composition having improved weather resistance by reducing the amount of the aromatic ring skeleton. However, although the proposed resin composition has improved color change due to light exposure, there remains a problem regarding the occurrence of vitiligo. In addition, since the proposed acid anhydride curing agent is affected by moisture and the physical properties of the cured product are deteriorated, it is not preferable to use the acid anhydride curing agent for a prepreg for which a certain storage period is assumed.

International Publication No. 2003/002661 Pamphlet

  An object of the present invention is to provide a resin composition that hardly causes yellowing or vitiligo even when exposed to light, a prepreg using the resin composition, and a fiber-reinforced composite material thereof.

  As a result of intensive studies, the present inventor has used hydrogenated bisphenol A type epoxy resin and an epoxy resin containing a skeleton represented by the structural formula (I) as a main agent, and dicyandiamide and / or a boron halide complex as a curing agent. Thus, a resin composition with less yellowing and white spots even when exposed to light was obtained.

  That is, hydrogenated bisphenol A type epoxy resin (A) and epoxy resin (B) containing a skeleton represented by structural formula (I) are included as a resin, and dicyandiamide and / or boron halide complex is used as a curing agent (C). A resin film using the resin composition, a prepreg obtained by impregnating a fiber base material with the resin composition, a fiber-reinforced composite material obtained by laminating the resin film, and the resin composition And a fiber reinforced composite material using a fiber base material. Furthermore, it is a fiber reinforced composite material obtained by laminating the prepreg only on the outer layer that will be exposed to light, and a fiber reinforced composite material obtained by laminating the resin film only on the outer layer that will be exposed to light. The resin composition of the present invention preferably contains an ultraviolet absorber, an antioxidant, and a light stabilizer. It is preferable to apply a protective film to the exterior that will be exposed to light. The protective film is preferably a paint or a resin film.

(式中、Ｒは、水素原子、又は、炭素数１〜３のアルキル基を示し、ｎは自然数を示す)

(In the formula, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents a natural number.)

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a resin composition that hardly causes yellowing or vitiligo even when exposed to light, a prepreg using the resin composition, and a fiber-reinforced composite material thereof.

It is a figure which shows the panel manufacturing method of the fiber reinforced composite material of this invention, and is sectional drawing which showed the structure of bagging.

"Hydrogenated bisphenol A epoxy resin (A)"
As the hydrogenated bisphenol A type epoxy resin (A) used in the present invention, a resin having an appropriate molecular weight can be selected. The hydrogenated bisphenol A type epoxy resin (A) can be obtained industrially, for example, from Nippon Steel Chemical Co., Ltd. as ST-3000 and ST-4000D, and from Mitsubishi Chemical Co., Ltd. as YX8000. In order to obtain a resin composition having excellent weather resistance, the structure of the hydrogenated bisphenol A type is important, and it may be either actually hydrogenated or not hydrogenated. The number of functional groups of the epoxy group is not particularly limited as long as it is bifunctional or more.

"Epoxy resin (B) containing skeleton represented by structural formula (I)"
The epoxy resin (B) containing a skeleton represented by the structural formula (I) can be industrially obtained, and can be obtained as, for example, EHPE-3150 from Daicel Chemical Industries, Ltd. The number of functional groups of the epoxy group is not particularly limited as long as it is bifunctional or more.
If the blending ratio of the hydrogenated bisphenol A type epoxy resin (A) and the epoxy resin (B) containing the skeleton represented by the structural formula (I) is 90:10 to 20:80 in mass ratio, the prepreg can be manufactured. It is preferable because it has a suitable viscosity and is excellent in weather resistance.

"Curing agent (C)"
The curing agent (C) is dicyandiamide and / or a boron halide complex. By using dicyandiamide and / or boron halide complex, deterioration of physical properties of the prepreg due to moisture can be suppressed, and a good fiber-reinforced composite material can be obtained. Dicyandiamide is commercially available. For example, it can be obtained from Mitsubishi Chemical Corporation as jER cure DICY15. The preferred blending amount of dicyandiamide is based on the number of moles of epoxy groups calculated from the epoxy equivalent of the hydrogenated bisphenol A type epoxy resin (A) and the epoxy resin (B) containing a skeleton represented by the structural formula (I). The amount of dicyandiamide active hydrogen equivalent is 1 to 0.6 equivalent. More preferably, it is 0.7 equivalent. The boron halide complex is commercially available. For example, it can be obtained from Huntsman as a boron chloride amine complex DY9577. A preferable blending amount is 4 to 15 parts, more preferably 8 to 12 parts, and both heat resistance and strength are excellent. Particularly preferred is 9 parts.

A curing aid can be used in the resin composition of the present invention. Examples include urea compounds, imidazoles, and tertiary amines. Examples of the urea compound include diphenyldimethylurea and toluenebisdimethylurea.
The resin composition of the present invention is preferably used with various ultraviolet absorbers, antioxidants, light stabilizers and the like having a function of improving weather resistance.
A well-known thing can be used for a ultraviolet absorber, For example, ultraviolet absorbers, such as a benzotriazole type absorber, a triazine type absorber, a salicylic acid derivative type absorber, a benzophenone type absorber, can be mention | raise | lifted. Preferably, LA-31 manufactured by ADEKA is used.
A well-known thing can be used for antioxidant, For example, a phenolic antioxidant, a phosphite type antioxidant, and a sulfur type antioxidant are mentioned. Preferred are AO-50 and AO-412S manufactured by ADEKA.
A well-known thing can be used for a light stabilizer, For example, a hindered amine light stabilizer can be mentioned. Preferably, LA-62 manufactured by ADEKA is used.

A thermoplastic resin may be blended in the resin composition of the present invention as necessary. Examples of the thermoplastic resin include phenoxy resin, polyvinyl formal, and polyethersulfone.
The resin composition of the present invention may contain additives as necessary. Curing accelerator, silicone oil, natural wax, synthetic wax, metal salt of linear fatty acid, acid amide, ester, paraffin and other mold release agent, crystalline silica, fused silica, calcium silicate, alumina, carbonic acid Powders such as calcium, talc and barium sulfate, inorganic fillers such as glass fiber and carbon fiber, flame retardants such as chlorinated paraffin, bromotoluene, hexabromobenzene and antimony trioxide, colorants such as carbon black and bengara, A silane coupling agent or the like can be used.

  In general, the resin composition of the present invention can make a fiber-reinforced composite material using a fiber base material. Examples of the fiber base material include carbon fiber, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, boron fiber, high-strength polyethylene fiber, tungsten carbide fiber, PBO fiber, glass fiber, and the like. You may use more than one species in combination. Carbon fiber is preferable. The fiber base material is used in the form of a tow as it is, in the form of a unidirectional material in which reinforcing fiber tows are aligned in one direction, in the form of a woven fabric, in the form of a non-woven fabric composed of short cut reinforcing fibers, etc. The In the case of woven fabrics, stitched sheets that are stitched so as not to unravel sheets that are aligned in one direction or sheets that are laminated at different angles, such as plain weave, twill weave, satin weave, or non-crimp fabric Etc. can be illustrated. Among these, a unidirectional material is preferable because the obtained fiber-reinforced composite material has excellent mechanical properties. From the viewpoint of handleability, a woven fabric is preferable. The prepreg of the present invention is not particularly limited in the fiber basis weight.

There is no special restriction | limiting in the manufacturing method of the resin composition of this invention, a prepreg, and a fiber reinforced composite material. It can be manufactured by a general method. The resin composition of the present invention can be prepared with a glass flask, a kneader, a planetary mixer, a general stirring heating kettle, a stirring pressure heating kettle or the like.
The prepreg of the present invention can be produced by a hot melt film method, a lacquer method or the like.

  When manufacturing a fiber reinforced composite material from a prepreg using the resin composition of the present invention, a general manufacturing method such as an autoclave molding method, an oven molding method, a press molding method, a continuous press molding method, a pultrusion molding method, an internal pressure molding method, etc. Is applicable. A preferable curing temperature is 130 ° C to 150 ° C. Moreover, it can manufacture also by the method which does not use prepregs, such as a film infusion and RTM.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention does not receive a restriction | limiting by this.

  The raw materials and fiber materials of the resin composition are shown in Table 1.

<Production of resin plate>
The epoxy resin composition was poured between two pieces of glass (2 mm thickness) having been subjected to a release treatment with a thickness of 2 mm, and heat cured at 130 ° C. for 2 hours to obtain a resin plate.

<Measurement of Tg by DMA>
The panel of the resin plate was cut into a test piece (length 55 mm × width 12.7 mm, thickness 2 mm). ARES-RDA manufactured by TA Instruments was used as a measuring device. Measurement was performed under the conditions of a measurement frequency of 1 Hz and a temperature increase of 5 ° C./min. The log G ′ was plotted against the temperature, and the temperature obtained from the intersection of the approximate straight line of the flat region before the log G ′ transition and the approximate straight line of the region where the G ′ transition was recorded as G′−Tg.

<Bending characteristics of resin plate>
The panel of the resin plate was cut into a test piece (length 60 mm × width 8 mm, thickness 2 mm). Bending characteristics using a universal testing machine manufactured by Instron with a three-point bending jig (3.2 mmR for both indenter and support, distance between supports; 40 times the test piece thickness, crosshead speed: 2 mm / min) Was measured.

<Weather resistance test>
As a measuring device, Sunshine Weather Meter WEL-SUN-HC manufactured by Suga Test Instruments Co., Ltd. was used. The temperature inside the tank was set to 63 ± 3 ° C. and humidity was 50% Rh, and pure water was dropped for 12 minutes in 60 minutes per cycle. A fiber reinforced composite material panel cut into a test piece (length 6 cm × width 7 cm) was attached to the apparatus, and the surface state of the test piece after 600 hours exposure was visually observed at a distance of about 30 cm. When the appearance was observed, the case where there was vitiligo was marked with “X”, and the case where there were no vitiligo and other abnormalities was marked as “◯”. Further, Lab was measured using a color difference meter, and the color difference ΔE before and after the weather resistance test was calculated by a conventional method.

<Example 1>
A master batch was prepared by uniformly dispersing a part of ST-3000, DICY15 and DCMU with a three-roll mill with the composition shown in Table 2. The remaining ST-3000, ST-4000D, EHPE3150, AO-50, AO-412S, and LA-31 were dissolved in a glass container at 140 ° C. to prepare a master batch. The two types of master batches and LA-62 were mixed at 65 ° C. in a glass container to obtain a resin composition A. This was heat-cured to obtain a resin plate. The Tg and bending characteristics of the resin plate were measured. The results are shown in Table 2.
Subsequently, carbon fiber fabric TR3110M manufactured by Mitsubishi Rayon Co., Ltd. was prepared as a fiber base material. The basis weight of the resin film was set so that the resin content of the prepreg was 40% by mass, and the resin composition A was applied to release paper with a film coater at 65 ° C. to obtain a resin film. The obtained resin film was bonded to both sides of the fiber base material, and the fusing press (Asahi Textile Machinery Co., Ltd., JR-600S, treatment length 1340 mm under conditions of temperature 90 ° C., pressure 0.2 MPa, feed rate 1 m / min. , The pressure was cylinder pressure), and prepreg 1 was obtained. The obtained prepreg 1 was laminated, and the laminated body was bagged with the configuration shown in FIG. Further, a vacuum pump was connected to the drawing port and preliminary deaeration was performed at room temperature, followed by heating and curing in an autoclave at a pressure of 0.3 MPa and 130 ° C. for 2 hours to obtain a fiber-reinforced composite material 1.
A test piece was cut out from the panel of the obtained fiber reinforced composite material 1, and a weather resistance test was performed. The results are shown in Table 2.

<Example 2>
A master batch was prepared by uniformly dispersing a part of ST-3000, DICY15 and DCMU with a three-roll mill with the composition shown in Table 2. The remaining ST-3000, EHPE3150 and AO-50, AO-412S, LA-31 were dissolved in a glass container at 140 ° C. to prepare a master batch. The two types of master batches and LA-62 were mixed at 65 ° C. in a glass container to obtain a resin composition B. The same procedure as in Example 1 was performed except that the resin composition was changed to B.

<Example 3>
ST-3000, EHPE3150, AO-50, AO-412S, and LA-31 having the composition shown in Table 2 were dissolved in a glass container at 140 ° C. to prepare a master batch. A master batch, DY9577 and LA-62 were mixed in a glass container at 65 ° C. to obtain a resin composition C. The same procedure as in Example 1 was conducted except that the resin composition was C.

<Comparative Example 1>
A master batch was prepared by uniformly dispersing a part of ST-3000, DICY15 and DCMU with a three-roll mill with the composition shown in Table 2. The remaining ST-3000, ST-4000D and AO-50, AO-412S, LA-31 were dissolved in a glass container at 140 ° C. to prepare a master batch. The two types of master batches and LA-62 were mixed at 65 ° C. in a glass container to prepare a resin composition D. The same procedure as in Example 1 was conducted except that the resin composition was changed to D.

  As shown in Table 2, a fiber-reinforced composite material having good weather resistance was obtained from the prepreg using the resin composition of the present invention. In Comparative Example 1 in which no epoxy resin (B) was used, poor appearance (white spots) occurred.

<Examples 4 to 11>
A master batch was prepared in the same manner as in Example 1 with the composition shown in Table 3, and then mixed with LA-62 to obtain resin compositions E to L, respectively. The obtained resin composition was heat-cured to obtain a resin plate. The Tg and bending characteristics of the resin plate were measured. The results are shown in Table 3.

<Comparative Examples 2 and 3>
A master batch was prepared in the same manner as in Comparative Example 1 with the composition shown in Table 3, and then mixed with LA-62 to obtain resin compositions M and N, respectively. The obtained resin composition was heat-cured to obtain a resin plate. The Tg and bending characteristics of the resin plate were measured. The results are shown in Table 3.

  As shown in Table 3, a fiber-reinforced composite material having good bending characteristics was obtained from the prepreg using the resin composition of the present invention. In the comparative example not using the epoxy resin (B), the bending strength was inferior.

DESCRIPTION OF SYMBOLS 1 Sealant 2 Release film 3 Nonwoven fabric 4 Nylon back film 5 Glass yarn 6 Laminate 7 Pressure plate 8 Vacuum suction port 9 Tool

Claims (13)

A hydrogenated bisphenol A type epoxy resin (A) and an epoxy resin (B) containing a skeleton represented by formula (I) as a resin;
An epoxy resin composition comprising dicyandiamide and / or a boron halide complex as a curing agent (C).   The resin composition according to claim 1, comprising an ultraviolet absorber.   The resin composition according to claim 1, comprising an antioxidant.   The resin composition according to claim 1, comprising a light stabilizer.   A resin film comprising the resin composition according to claim 1.   A prepreg obtained by impregnating a fiber base material with the resin composition according to claim 1.   A fiber-reinforced composite material comprising the resin composition according to claim 1 and a fiber base material.   A fiber-reinforced composite material obtained by laminating the prepreg according to claim 6.   A fiber-reinforced composite material obtained by laminating the prepreg according to claim 7 on an outer layer.   A fiber-reinforced composite material obtained by laminating the resin film according to claim 5 on an outer layer.   The fiber-reinforced composite material according to claims 7 to 10, wherein a protective film is applied to the outer layer.   The fiber-reinforced composite material according to claim 11, wherein the protective film is a coating.   The fiber-reinforced composite material according to claim 11, wherein the protective film is a resin film.

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