JPH0820654A - Epoxy resin composition and prepreg using the same - Google Patents

Abstract

PURPOSE:To obtain a resin composition comprising an epoxy resin, a thermoplastic resin, a specific curing agent, a curing accelerator and specific whiskers, excellent in handleability, storability, moldability, molded product surface, compression strength and adhesivity, and useful for fiber-reinforced composite materials such as fishing rods. CONSTITUTION:This resin composition comprises (A) an epoxy resin such as a bisphenol A epoxy resin or novolak epoxy resin, (B) a thermoplastic resin such as a phenoxy resin or polyvinyl formal, (C) a latent amine curing agent such as dicyandiamide or adipic acid dihydrazide, (D) a curing accelerator such as an imidazole derivative or an amine adduct compound, and (E) whiskers having an aspect ratio of 3-500 (e.g. aluminum borate or calcium carbonate whiskers).

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is excellent in handling workability such as proper tackiness (adhesiveness) and drapeability (flexibility) of prepreg and storage stability at room temperature, and has a small resin flow during molding. , Especially when molding tubular moldings made of fiber reinforced resin such as fishing rods and golf shafts, there is no falling of the furnace, there are no defects such as scratches on the polished surface of these moldings, and the composite material characteristics excellent in compressive strength, adhesiveness, etc. The present invention relates to an epoxy resin composition suitable for a fiber-reinforced composite material.

[0002]

BACKGROUND OF THE INVENTION Fiber-reinforced composite materials such as carbon fibers are lightweight, have high strength and high elastic modulus, and are in the form of composites with resins, so-called prepregs, such as fishing rods, golf club shafts, and tennis. Sports / leisure fields such as rackets, industrial materials such as leaf springs and honeycomb structure materials, as well as automobile-related, aircraft materials, structural materials such as ships, electronic materials,
Widely used for various purposes such as civil engineering and building materials.

By the way, as a matrix resin of such a prepreg for a fiber-reinforced composite material, an epoxy resin as a main component, a rubber component (JP-A-60-39286) or a thermoplastic resin (JP-A-62-169829) has been used.
No. JP-A-63-221122) and epoxy resin, and a filler having a particle diameter of 10 times or less the diameter of the reinforcing single fiber, for example, graphite powder, carbon black, aluminum powder, silica. Add powder,
Those obtained by lowering the fluidity of the matrix resin during prepreg molding (Japanese Patent Laid-Open No. 59-227931) and the like are used for the production of prepreg.

Particularly for tubular fiber-reinforced composite materials such as fishing rods and golf shafts, a sheet-shaped prepreg in which carbon fibers or glass fibers are aligned in one direction or a prepreg obtained by impregnating a woven fabric of the above-mentioned reinforcing fibers with a matrix resin is released. Wrap the taped mandrel coated with the agent in the longitudinal direction in the direction according to the desired design, and then wind the heat-shrinkable tape spirally using a tape winder, etc. while gradually overlapping it. Then, put it in a heating furnace, harden the matrix resin while applying tightening force with heat shrinkable tape, remove from the heating furnace and remove the tape after cooling, pull out the mandrel with a core removing machine etc. . However, the conventional prepreg has a drawback that the prepreg moves from the large diameter side of the mandrel toward the small diameter side during molding, that is, so-called furnace drop occurs. This is because heating causes the matrix resin to have low viscosity and to increase fluidity, so when the tightening force of the heat-shrinkable tape is applied in such a state, the mandrel has a taper, and the mandrel has a taper from the large diameter side to the small diameter side. A component force is generated and a so-called furnace drop occurs in which the prepreg moves in this direction. When this furnace drop occurs, the distribution of the matrix resin and the reinforcing fibers becomes uneven, and the desired physical properties of the composite material cannot be obtained, and it also causes defects in the molded product or warpage of the small diameter portion.

On the other hand, Japanese Patent Application Laid-Open No. 57-22636 discloses that
Prior to winding the prepreg around the mandrel, a method has been proposed in which a thread or a thread impregnated with a thermosetting resin is spirally wound in the longitudinal direction of the mandrel and the friction thereof prevents the furnace from falling. However, in this method, not only the effect of preventing the furnace from falling is not sufficient, but also the yarn remains in the molded product, which is not preferable in terms of characteristics. Further, in Japanese Patent Laid-Open No. 59-159315, a temperature of 130 ° C. is applied to a matrix resin for prepreg before winding the prepreg around a mandrel.
There is proposed a method of preventing the furnace from falling by applying a thermosetting resin having a gel time of 80% or less of the above resin to the mandrel. However, this method requires a resin for undercoating whose gel time is adjusted by B-stage formation, and prior to molding, the step of applying this undercoating resin,
Air-drying is required, which significantly reduces productivity.

Further, regarding the handling property (tack and drape property) of the prepreg at the time of working, not only the productivity at the time of shaft winding but also the cause of defects (scratches, etc.) on the surface of the molded product are required to have appropriate characteristics. To be done. These properties require a prepreg that is less affected by working temperature and has less temperature dependence. If the tackiness is too strong, air is likely to be entrained at the time of winding, and if it is too low, workability such as laminating the prepreg deteriorates. In addition, when the drape property is insufficient, the prepreg is wound at the end portion of the winding, and particularly carbon fibers having a high elastic modulus may be broken. However, these factors appear on the surface as defects such as scratches at the time of polishing and coating after molding the shaft, causing defective products and deteriorating the physical properties, resulting in a significant reduction in yield.

As described above, the prepreg using the conventional matrix resin composition has appropriate workability and excellent composite material properties, does not fall down during molding, and is capable of polishing molded products.
It has been extremely difficult to provide a prepreg with no defects on the coated surface.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks of the conventional method, prevent the furnace from falling during molding without performing a pretreatment step, and deteriorate the physical properties of the composite material. It is possible to obtain a fiber-reinforced composite material molded product having desired properties without any need. Further, a prepreg using the epoxy resin composition of the present invention has a normal winding temperature (20
(~ 30 ° C), it has a moderate winding workability with little temperature dependence and the resin flow during molding can be freely controlled, so defects (such as scratches) on the surface of the molded product after polishing
It is intended to provide an excellent molded product having no

[0009]

Means for Solving the Problems That is, the present invention provides the following components (A), (B), (C), (D) and (E) (A) epoxy resin (B) thermoplastic resin (C) latent Amine amine curing agent (D) Curing accelerator (E) Epoxy resin composition containing whiskers with aspect ratio of 3 or more and 500 or less, and a prepreg obtained by impregnating this with a reinforcing fiber.

The present invention will be described in more detail below. The epoxy resin which is the component (A) used in the present invention is not particularly limited, and includes a bisphenol A type epoxy resin and other glycidyl ether type epoxy resins, for example,
Bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl amine type epoxy resin, naphthalene type epoxy resin, brominated bisphenol A type epoxy resin, glycidyl ester type epoxy resin, Examples thereof include cycloaliphatic epoxy resins and heterocyclic epoxy resins. If desired, urethane-modified epoxy resin, rubber-modified epoxy resin, alkyd-modified epoxy resin, etc. may be used. Among these, bisphenol A type epoxy resin and novolac type epoxy resin are preferable from the viewpoint of balance of handling property, economical efficiency, and physical properties of composite material, but two or more kinds of these can be appropriately mixed and used according to required characteristics.

The thermoplastic resin as the component (B) includes, for example, phenoxy resin, polyvinyl butyral, polyvinyl formal, polyvinyl phenyl acetal and other acetal resins, polyether sulfone, polysulfone, polyether imide, polyarylate and the like. It is not limited. These resins change the viscosity characteristics of the epoxy resin composition and contribute to the improvement of prepreg handleability in a wide temperature range. One or two or more of these resins are appropriately used, and the amount is 1 to 40 with respect to the component (A).
Parts by weight, preferably 1 to 20 parts by weight are used. If it is less than 1 part by weight, the effect of improving the viscosity characteristic is small, and it is 40
When the amount is more than parts by weight, the viscosity of the resin composition on the high temperature side tends to be high, and the impregnability into the fiber reinforcing material is lowered in the prepreg forming step by the hot melt method, which is not preferable.

Examples of the latent amine-based curing agent as the component (C) include dicyandiamide (1-cyanoguanidine), methylguanidine, ethylguanidine, propylguanidine, butylguanidine, dimethylguanidine,
Guanidine-based curing agents such as trimethylguanidine, phenylguanidine, diphenylguanidine, toluylguanidine, 2,3-guanylurea, benzoyldicyandiamide, 2,6-xylenylbiguanide and phenylbiguanide can be mentioned. Further, for example, adipic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, sebacic acid dihydrazide, oxalic acid dihydrazide,
Phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, p-oxybenzoic acid hydrazide, salicylic acid hydrazide, maleic acid dihydrazide,
Examples thereof include polyhydric carboxylic acid polyhydrazide-based curing agents such as dimer acid dihydrazide and azelaic acid dihydrazide. These latent amine-based curing agents are
Although it does not substantially act as a curing agent, it is activated at a certain point of 50 ° C. or higher, preferably at a certain point between 50 ° C. and 80 ° C. and acts as a curing agent. Two or more kinds can be mixed and used. However, dicyandiamide and adipic acid dihydrazide are preferable from the viewpoints of storage stability, economical efficiency, and physical properties of composite materials.
If desired, another type of curing agent can be used in combination.
Examples thereof include boron trifluoride amine complex, amine imide, diaminomaleonitrile, guanamines, phenol resin, melamine resin and urea resin. The amount of these curing agents used is usually such that the active hydrogen equivalent of the curing agent is around 0.2 to 1.2 equivalents relative to 1 equivalent of the epoxy group, although the physical properties of the cured product are good, but the storage stability is good. Etc. are adjusted as appropriate according to other required characteristics. Usually, it is 1 to 40 relative to 100 parts by weight of the components (A) and (B).
Suitable is parts by weight, preferably 1 to 20 parts by weight. If it is less than 1 part by weight, the curing tends to be insufficient, and if it is more than 40 parts by weight, the properties of the cured product are likely to deteriorate, which is not preferable.

Examples of the curing accelerator of the component (D) include imidazole derivatives and salts thereof (for example, "Curesol" manufactured by Shikoku Kasei), amine adduct compounds (for example, "Amicure" manufactured by Ajinomoto Co.), and microcapsules (for example, Asahi Kasei). "Novacure" manufactured by the company), urea compounds (for example, 3-
(3,4-dichlorophenyl) -1,1-N dimethylurea, 3-phenyl-1,1-dimethylurea, 3- (4-
Chlorophenyl) -1,1-dimethylurea, 3- (4-
Methoxyphenyl) -1,1 dimethylurea, trimethylurea) and the like show excellent effects. The addition amount of these curing accelerators is 1 with respect to 100 parts by weight of the components (A) and (B).
˜20 parts by weight is used, but preferably 1 to 10 parts by weight. If the amount is less than 1 part by weight, the curing acceleration effect is small, and if the amount is more than 10 parts by weight, the storage stability of the prepreg deteriorates, which is not preferable.

The whiskers as the component (E) have an aspect ratio (fiber length / fiber diameter) of 3 or more, 50 or more.
0 or less, preferably 450 is used. When the aspect ratio is less than 3, the resin flow at the time of molding is not sufficiently lowered, and when the aspect ratio is 500 or more, the impregnability into reinforcing fibers or the workability of prepreg and the moldability are adversely affected. These whiskers are not particularly limited, and examples thereof include aluminum borate, calcium carbonate, silicon carbonate, silicon nitride, potassium titanate, basic magnesium sulfate, zinc oxide, graphite, magnesia, calcium sulfate, magnesium borate, and diborate. One or more of titanium boride, α-alumina, chrysotile, etc. are appropriately used. Of these, aluminum borate, calcium carbonate, and silicon carbide whiskers are particularly excellent in properties and economical efficiency. The addition amount of these whiskers was 0. 0 with respect to 100 parts by weight of the components (A) and (B).
05 to 30 parts by weight, preferably 0.5 to 15 parts by weight are used. If the amount is less than 0.05 parts by weight, it is difficult to obtain a sufficient decrease in the flow during molding, and if the amount is more than 30 parts by weight, the viscosity of the resin tends to increase, and the impregnating property into the fiber in the prepreg-forming step decreases, which is not preferable.

In addition to the above components, if desired, an epoxide-reactive diluent may be added to the extent that reactivity, heat resistance, toughness, storage stability and the like are not deteriorated. Examples of reactive diluents include phenyl glycidyl ether, butyl glycidyl ether, alkyl glycidyl ether,
Examples thereof include styrene oxide, octylene oxide and mixtures thereof. In addition, silanes, coupling agents such as titanate compounds, release agents such as higher fatty acids and waxes, flame retardants such as halogens and phosphorus compounds,
Additives such as defoaming agents and coloring agents can also be used if necessary.

The reinforcing fibers used in the production of these prepregs include carbon fibers, glass fibers, aramid fibers, polyester fibers, silicon carbide fibers, boron fibers,
Alumina fibers, polyethylene fibers, etc. may be mentioned, and one kind or two or more kinds of them may be appropriately used. To manufacture prepreg, general prepreg manufacturing methods can be applied,
The reinforcing substrate may be impregnated directly by the hot melt method or by the film method, or may be impregnated directly by the solvent impregnation method or after film formation. However, the solvent impregnation method requires a solvent distillation step. .

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. The abbreviations of the compounds used in the examples and the test methods are as follows. <Raw material> “E828”: Bisphenol A type epoxy resin (made by Yuka Shell Co., Ltd.) “E1001”: Bisphenol A type epoxy resin (made by Yuka Shell Co., Ltd.) “DEN438”: Phenol novolac type epoxy resin (made by Dow Chemical Co., Ltd.) ) "YP50P": Phenoxy resin (manufactured by Tohto Kasei Co., Ltd.) PVF: Polyvinyl formal "Vinilex L" (manufactured by Chisso Co.) DICY: Dicyandiamide (manufactured by Yuka Shell Co., Ltd.) DCMU: 3- (3,4-dichlorophenyl) -1 , 1
-N dimethyl urea (manufactured by Hodogaya Chemical Co., Ltd.) "Arborex Y", "YS2": Aluminum borate whiskers (manufactured by Shikoku Chemicals Co., Ltd.) <Aspect ratio = 10 to 60>"Whiscals": calcium carbonate whiskers ( Shikoku Kasei Co., Ltd.) <Aspect ratio = 20 to 60>"R202": fine silica, "Aerosil R202"
(Made by Nippon Aerosil Co., Ltd.)

<Measurement of resin flow> 10 prepregs
Cut into 0 × 100 mm, laminate 4 ply, perforated film on top and bottom, glass cloth on outermost layer, press at 120 ° C., 3.5 kg / cm ² with a heating press, and measure resin flow.

<Evaluation of Winding and Furnace Falling> A prepreg was formed in an oblique layer (± 45 °) 3 ply and a straight layer (0 °) 3
It was cut to be ply. The cut prepreg was wound on a mandrel coated with a release agent by a rolling table. The heat shrink tape was then wrapped with a tape rubbing device. Suspend in a heating furnace with the large diameter side up, 12
Cured at 0 ° C./2 hours. After cooling to room temperature, measure the furnace falling.

<Handling workability: tackiness, drapeability> (Comprehensive from the pasted state of the oblique layer at 23 ° C and 30 ° C, the possibility of correction, the hardness of manual winding, the shaving after rolling the table, etc.) ○) Good, ×… Poor

<Bending test (3-point bending)> ASTM D7
According to 90, device: UTM-made by Toyo Baldwin
Using 5T, sample shape: (length 100 mm, width 10
mm, thickness 2 mm), span length: 80 mm, crosshead speed: 2 mm / min.

<ILSS> According to ASTM D2344, sample shape: (length 12 mm,
Width 10 mm, thickness 2 mm), span length: 8 mm, crosshead speed: 2 mm / min.

Example 1 15 parts by weight of "E828" (excluding the amount used for the masterbatch) and 3 parts of "E1001"
6 parts by weight, 34 parts by weight of “DEN438” were melt mixed at 80 ° C., then heated to 150 ° C., 8 parts by weight of “YP50P” were added, dissolved by stirring for 1 hour, and cooled to room temperature to obtain a base resin. It was This base resin "Arborex Y"
Of 5 parts by weight and DICY of 4 parts by weight in a master batch were added, and the mixture was uniformly mixed with a stirrer at 70 ° C. for 30 minutes.
Then, 3 parts by weight of DCMU was added and stirred for 10 minutes to obtain a resin composition of the present invention. The resin composition thus obtained and carbon fiber (“Torayca T300” manufactured by Toray Industries, Inc., elastic modulus 24 t
on / mm ² ), a unidirectional prepreg was produced by the hot melt method to obtain the prepreg of the present invention. The carbon fiber areal weight of this prepreg is 150 g / m ² , and the resin amount is 35%.
Met. This prepreg was laminated in 14 plies in one direction and cured at 120 ° C. for 2 hours in an autoclave to form a unidirectional laminated plate having a thickness of about 2 mm. The physical properties (Vf = 60% conversion value) of the obtained composite material are shown in Table-1.

Then, the winding evaluation was carried out at 23 ° C. and 30 ° C. This prepreg had no temperature dependency and had very good handling workability (tack and drape). The 10 molded articles obtained did not have any furnace falling. Furthermore,
The surface of this molded product was polished with a polishing machine and observed for surface defects (scratches, etc.), and good molded products without any defects were obtained.

(Example 2) A resin composition of the present invention was obtained in the same manner as in Example 1 except that 5 parts by weight of "Arbolex YS2" was used as the component (E). The workability of this prepreg was good, the molded product did not fall off the furnace, and no defects were observed on the polished surface.

(Examples 3 and 4) According to the composition of Table-1,
As the component (B), 3 parts by weight or 5 parts by weight of PVF is dissolved and mixed at 165 ° C./3 hours, and (E)
"Arbolex YS2" or "Whiscal" as an ingredient
A prepreg was produced in the same manner as in Example 1 except that 5 parts by weight of each of the above was used. The workability of the prepreg was good, and no defects were observed in the molded product.

(Comparative Example 1) According to the composition of Table-1, (B)
A prepreg was produced by the same method as in Example 1 except that the component and the component (D) were not used. The basis weight of the prepreg was 150 g / m ² and the resin amount was 35%. This prepreg had high tackiness, large resin flow, and the furnace fell. In addition, scratches on the polished surface of the molded product were also noticeable.

(Comparative Example 2) (B) without using the component (D)
A prepreg was produced by the same method as in Example 1 except that 5 parts by weight of PVF was used as a component. This prepreg had relatively good workability, but the resin flow was large and the furnace fell. Also, scratches were generated on the polished surface of the molded product.

Comparative Examples 3 and 4 Prepregs having the compositions shown in Table 1 were produced in the same manner as in Example 1 except that "Aerosil R202" was used as the inorganic filler or whiskers were used as the component (E). In each case, scratches on the polished surface of the molded product or handling workability at 30 ° C. were poor.

[0030]

[Table 1]

[0031]

EFFECTS OF THE INVENTION The prepreg manufactured from the matrix resin containing the whiskers of the present invention can be appropriately adjusted in proper workability and resin flow at the time of molding, and can be molded by oven molding, internal pressure molding or the like. The law is flawless,
A molded product having excellent composite material properties can be obtained, which is extremely useful for improving reliability and productivity of the fiber-reinforced composite material.

Claims (8)

[Claims] 1. The following components (A), (B), (C), (D) and (E) (A) epoxy resin (B) thermoplastic resin (C) latent amine curing agent (D) curing Accelerator (E) An epoxy resin composition containing whiskers having an aspect ratio of 3 or more and 500 or less. 2. The epoxy resin composition according to claim 1, wherein the thermoplastic resin (B) is a phenoxy resin. 3. The epoxy resin composition according to claim 1, wherein the thermoplastic resin (B) is polyvinyl formal. 4. The epoxy resin composition according to claim 1, wherein the latent amine curing agent (C) is dicyandiamide. 5. The epoxy resin composition according to any one of claims 1 to 4, wherein the whiskers (E) are aluminum borate. 6. The epoxy resin composition according to any one of claims 1 to 4, wherein the whiskers (E) are calcium carbonate. 7. A prepreg obtained by impregnating reinforcing fiber with the epoxy resin composition according to claim 1. 8. The prepreg according to claim 7, wherein the reinforcing fibers are carbon fibers.