JPH068341B2 - Epoxy resin composition for prepreg - Google Patents

Description

TECHNICAL FIELD The present invention relates to an epoxy resin composition for prepreg, which is excellent in toughness, heat resistance / water resistance, and tack drape.

[Prior Art] A composite material composed of a reinforcing material such as carbon fiber, glass fiber and aromatic polyamide fiber and an epoxy resin takes advantage of its high specific strength and specific elastic modulus, and is used for premier sports applications such as golf shafts and fishing rods. Widely used for structural materials such as aircraft. However, the epoxy resin used for these composite materials is insufficient in performance for applications requiring greater strength, toughness, heat resistance and water resistance.

Currently, epoxy resins used for aircraft composite materials contain N, N, N ', N'-tetraglycidyldiaminodiphenylmethane as a main component, and diaminodiphenylsulfone is used as a curing agent. Although this resin composition has high heat resistance, it has a small resin elongation and becomes a brittle cured product. CFRP obtained from this resin composition exhibits excellent heat resistance but low toughness.

Many techniques have been proposed for improving the toughness of epoxy resins. One of the methods is to prevent the occurrence of cracks by adding a rubber such as acrylonitrile-butadiene copolymer to an epoxy resin, and then curing the epoxy resin to form a rubber phase as a separated phase, or the adhesive strength. (For example, JP-A-57-2).
1450). Other methods include adding and mixing thermoplastic resins such as polyethersulfone, polysulfone, and polyarylate with epoxy resin to suppress the propagation of cracks in the cured resin, or using this resin to improve carbon fiber reinforced composite materials. There are ways to improve toughness (eg THE BRIT
ISH POLYMER JOURNAL, Vol.15, MARCH, 1983.P.71,28th SA
MPE SYMPOSIUM, 1 983, P.367, JP-A-58-13412
6). However, the latter method does not impair the heat resistance and water resistance of the composite material, but the blending amount of the thermoplastic resin must be increased to a certain extent or more in order to have high toughness.

When the blending amount of the thermoplastic resin is increased, the viscosity of the epoxy resin becomes very high, impairing impregnation with the reinforcing material and curing failure are likely to occur in the production or molding process of the prepreg, and the tack and drape property of the prepreg is impaired. There arises a problem that it becomes impossible to perform a laminating operation or molding a complicated shape.

[Problems to be Solved by the Invention] An object of the present invention is to have an appropriate viscosity in the steps of producing a resin composition and producing / molding a prepreg for a composite material,
Another object of the present invention is to provide an epoxy resin composition for prepreg, which is excellent in toughness, heat resistance and water resistance and gives a prepreg having appropriate tack and drape properties.

[Means for Solving Problems] In the present invention, as an essential component, [A] N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane [B] N, N, O-triglycidylmetaaminophenol [ C] Bisphenol F type epoxy resin [D] Diaminodiphenyl sulfone [E] General formula The present invention relates to an epoxy resin composition for prepreg prepared by blending the polyether sulfone represented by

N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane used in the present invention includes ELM434 (Sumitomo Chemical Co., Ltd.), MY720 (Ciba Geigy Co., Ltd.),
It is commercially available under the trade name of YH434 (manufactured by Tohto Kasei Co., Ltd.). Since this epoxy resin is a tetrafunctional epoxy resin, it has the advantages that the crosslink density becomes high and a cured product having a high elastic modulus and high heat resistance can be obtained. However, it has the drawback that the elongation of the cured product is small and it is brittle. Considering these characteristics, the amount of N, N, N ', N'-tetraglycidyldiaminodiphenylmethane added is preferably 40 to 60% by weight in the epoxy resin component. When the amount is more than this range, the obtained cured product becomes brittle and the water resistance becomes poor. When the amount is reduced, the heat resistance and elastic modulus of the cured product decrease. Therefore, in these cases, the toughness and heat / water resistance of CFRP are lowered.

The N, N, O-triglycidylmethaaminophenol used in the present invention is commercially available under trade names such as ELM120 (Sumitomo Chemical Co., Ltd.) and YDM120 (Toto Kasei Co., Ltd.). This epoxy resin promotes curing and improves the elastic modulus of the cured product. However, since the addition of this resin reduces the water resistance of the cured product, the addition amount is preferably 10 to 30% by weight in the epoxy resin component.

The bisphenol F type epoxy resin used in the present invention is Epicron 830 (manufactured by Dainippon Ink and Chemicals, Inc.),
It is commercially available under the trade name of Epicoat 807 (produced by Yuka Shell Epoxy Co., Ltd.). The addition of this epoxy resin is highly preferable because it lowers the viscosity of the epoxy resin composition for prepreg of the present invention and improves the tack drape property. In addition, a compound having an appropriate viscosity can be obtained in the process of manufacturing and molding the prepreg, and workability can be greatly improved. However, a cured product obtained from this epoxy resin has a high resin elongation, but has a slightly low heat resistance.
Considering these characteristics, the addition amount of the bisphenol F type epoxy resin is preferably 20 to 50% by weight in the epoxy resin component.

Examples of epoxy resins other than the epoxy resin used in the present invention include bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin,
Examples include reaction diluents represented by glycidyl derivatives of glycerin, alicyclic epoxy resins, and the like. However, if a large amount of these epoxy resins is used, the heat resistance and water resistance or the tack drape property of the epoxy resin composition for prepreg of the present invention are lowered, so that the use amount is limited.

The curing agent diaminodiphenyl sulfone used in the present invention may be added theoretically so that 1 equivalent of amine is equivalent to 1 equivalent of epoxy. Further, depending on the adjustment of the curing speed and shelf life, and the heat resistance and water resistance of the resulting cured product, the amount of the curing agent added is preferably in the range of 0.7 to 1.3 equivalents relative to 1 equivalent of epoxy. The equivalent weight can be selected. Further, boron trifluoride / amine complex, imidazole compound, dicyandiamide and the like can be used as a curing accelerator.

The polyether sulfone represented by the general formula [I] used in the present invention was developed by Imperial Chemical Industry (UK) and is commercially available under the trade name of VICTREX. The amount of this polyether sulfone added is
1 to 100 parts of the epoxy resin for prepreg of the present invention
5 to 35 parts is preferable. When the amount is more than this range, the resin composition has a very high viscosity, so that only the prepreg having poor resin impregnation and poor tack drape property can be obtained. On the other hand, when the amount is less than this range, the toughness becomes low without the addition effect of polyether sulfone. In the present invention, it goes without saying that components other than [A] to [E] can be mixed and used within a range where the effect can be exhibited.

The mixing method of each component of the present invention is not particularly limited, and a preferable method can be appropriately selected according to the properties of the components and the mixed state or dispersed state of the target compound. As an example of the mixing method, there is a method of forming a homogeneous solution at a relatively low temperature using a solvent in which each of the components [A], [B], [C], [D] and [E] is dissolved. There is a method of mixing the components at a relatively high temperature without using a solvent. In the latter case, a method of first dissolving the epoxy resin and polyether sulfone at a relatively high temperature, then lowering the temperature, and then mixing the curing agent is preferably used.

The epoxy resin composition for prepreg of the present invention is preferably used as a resin for a composite material, and the carbon fiber used in this case is a tape, a sheet-shaped material, a mat-shaped material, a woven fabric, etc. arranged in a certain direction. It can be applied to such a form. Further, it can be used for reinforcing materials of advanced composite materials such as aramid fiber, boron fiber, silicon carbide fiber, and hybrids thereof.

[Operation] In the present invention, N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane, N, N, O-triglycidylmetaaminophenol, bisphenol F type epoxy resin, diaminodiphenyl sulfone and polyether sulfone are combined. Provides an epoxy resin composition for prepreg, which is excellent in toughness, heat resistance / water resistance, and tack drape. Furthermore, a good composite material can be obtained without causing any inconvenience in the step of blending each component and the step of impregnating the reinforcing material to produce a prepreg.

[Examples] The present invention will be described in more detail by the following examples. The amount of each component in the examples represents parts by weight, and the content of the epoxy resin is as follows.

Epoxy A: N, N, N ', N'-tetraglycidyldiaminodiphenylmethane, ELM43 manufactured by Sumitomo Chemical Co., Ltd.
4 Epoxy B: N, N, O-triglycidylmethaaminophenol, ELM120 made by Sumitomo Chemical Co., Ltd. Epoxy C: Bisphenol F type epoxy resin, Epicron 830 made by Dainippon Ink and Chemicals, Inc. Epoxy D: Bisphenol A type epoxy resin, oil Shell Epoxy Co., Ltd. made by Epoxy Coat 828 Epoxy E: Brominated Epoxy Resin, Dainippon Ink and Chemicals, Inc. Epicron 152 Epoxy F: Cresol Novolac Epoxy Resin, Dow Chemical Japan DEN485 Example 1 Epoxy A 50 parts, Epoxy B20 Section, epoxy C30
Parts and 17 parts of polyether sulfone were heated and stirred at 150 ° C., and after 30 minutes, a transparent viscous liquid was obtained. When this composition was cooled to 60 ° C. and 46 parts of diaminodiphenyl sulfone was uniformly dispersed, a resin composition having an appropriate tack drape at room temperature was obtained.

The viscosity-temperature characteristics of this resin composition were measured using a Rheopex analyzer (Iwamoto Seisakusho, cone plate type) at a set temperature rising rate of 3 ° C./min. The minimum viscosity is shown in Table 1.

100 parts of the above resin composition is mixed with methylene chloride / chloroform / methanol mixed solvent (53/43/4 weight ratio) 24
It was dissolved in 0 part to prepare a homogeneous solution. This solution was applied and impregnated on a plain weave cloth using Toray (“Torayca” T300 manufactured by Toray Industries, Ltd.) so that the resin content was 41% by weight. A uniform prepreg with moderate tack drape was obtained.24 prepregs were laminated and cured using an autoclave at 180 ° C for 2 hours under a pressure of 6 kg / cm ² to a thickness of about A composite material of 5 mm was obtained, and almost no resin flow from the composite material was observed after molding.

680 kg · c
m / cm (sample thickness) falling weight impact energy was applied. The damage caused by this impact test was measured using an ultrasonic flaw detection imaging device M400B type manufactured by Canon Holosonix.
The damaged area is shown in Table 1.

Using the above resin composition, a resin film is formed on silicon paper, and the film is used as "Torayca" T80.
0 The resin was heated and pressed so as to have a resin weight content of 35% on the unidirectionally arranged fiber, and a uniform unidirectionally arranged prepreg having a suitable tack drape property at room temperature was obtained.
Eight prepregs were stacked and cured in an autoclave at 180 ° C. for 2 hours under a pressure of kg / cm ² to obtain a unidirectionally laminated material having a thickness of about 1 mm. Shimadzu Autograph DSC
Using -10T, the tensile elongation at break in the fiber direction of the above composite material was measured under the condition of a crosshead speed of 1 mm / min. The results are shown in Table 1.

In the same way, 16 pieces of the above prepreg are piled up and the thickness is about 2 mm.
A unidirectional laminated material was obtained. Shimadzu Autograph IS-200
No. 0 was used to measure the tensile fracture elongation in the direction perpendicular to the fiber of the above composite material under the condition of a crosshead speed of 1 mm / min. The results are shown in Table 1.

Example 2 A resin composition was prepared in the same manner as in Example 1 except that 26 parts were added instead of 17 parts of polyether sulfone in Example 1, and a uniform and appropriate tack drape property was obtained at room temperature. A resin composition having was obtained. The viscosity-temperature characteristic of this resin composition was measured in the same manner as in Example 1. The results are shown in Table 1.

A prepreg was prepared from the above resin composition using a mixed solution of methylene chloride / chloroform / methanol in the same manner as in Example 1. The prepreg had a suitable tack drape at room temperature. From this prepreg, a falling weight impact test was conducted in the same manner as in Example 1 to measure the damaged area. The results are shown in Table 1.

Using the above resin composition and in the same manner as in Example 1, a uniform unidirectionally arranged prepreg having an appropriate tack drape at room temperature was obtained. Using this prepreg, the tensile elongation at break in the fiber direction and the direction perpendicular to the fiber was measured by the same method as in Example 1. The results are shown in Table 1.

In addition, almost no resin flow was observed from the composite material after molding.

Example 3 A resin composition was prepared in the same manner as in Example 1 except that 31 parts instead of 17 parts of polyether sulfone in Example 1 was added, and a uniform and appropriate tack drape property was obtained at room temperature. A resin composition having was obtained. The viscosity-temperature characteristic of this resin composition was measured in the same manner as in Example 1. The results are shown in Table 1.

A prepreg of the above resin composition was prepared in the same manner as in Example 1 using a mixed solvent of methylene chloride / chloroform / methanol. The prepreg had an appropriate tack drape property at room temperature. Using this prepreg, in the same manner as in Example 1,
The damaged area after the drop weight impact test was measured. The results are shown in Table 1. Also, almost no resin flow was observed from the composite material after molding.

Example 4 40 parts of epoxy A, 30 parts of epoxy B, 30 parts of epoxy C30
Part, polyether sulfone 34 parts and diaminodiphenyl sulfone 36 parts, a resin composition was prepared in the same manner as in Example 1. As a result, a resin composition having a uniform and appropriate tack drape at room temperature was obtained. Was obtained. The viscosity-temperature characteristic of this resin composition was measured by the same method as in Example 1. The results are shown in Table 1.
Shown in.

A prepreg of the above resin composition was prepared in the same manner as in Example 1 using a mixed solvent of methylene chloride / chloroform / methanol. The prepreg had an appropriate tack drape property at room temperature. Using this prepreg, in the same manner as in Example 1,
The damaged area after the drop weight impact test was measured. The results are shown in Table 1. Also, almost no resin flow was observed from the composite material after molding.

When the above resin composition was cured at 180 ° C. for 2 hours, a transparent resin cured product was obtained. The glass transition temperature (measured at a temperature rising rate of 40 ° C./min of a differential differential calorimeter) of this cured resin was 205 ° C., and the water absorption rate (boiling / 2
(0 hours) was 2.5%. In the same manner, a resin cured plate having the same composition as above was prepared without adding polyether sulfone. This had a glass transition temperature of 205 ° C. and a water absorption rate of 3.0%.

From this example, it was clarified that a resin cured product excellent in heat resistance and water resistance and in which polyether sulfone was uniformly dispersed was obtained.

Example 5 60 parts of epoxy A, 20 parts of epoxy B, epoxy C20
Part, polyether sulfone 17 parts and diaminodiphenyl sulfone 45 parts, a resin composition was prepared in the same manner as in Example 1. As a result, a resin composition having a uniform and appropriate tack drape at room temperature was obtained. Was obtained. The viscosity-temperature characteristic of this resin composition was measured by the same method as in Example 1. The results are shown in Table 1.
Shown in.

A prepreg of the above resin composition was prepared in the same manner as in Example 1 using a mixed solvent of methylene chloride / chloroform / methanol. The prepreg had an appropriate tack drape at room temperature. Using this prepreg, in the same manner as in Example 1,
The damaged area after the drop weight impact test was measured. The results are shown in Table 1. Also, almost no resin flow was observed from the composite material after molding.

Comparative Example 1 A resin composition was prepared in the same manner as in Example 1 for a system consisting of 60 parts of epoxy A, 40 parts of epoxy B, 20 parts of diaminodiphenyl sulfone and 33 parts of polyether sulfone, and showed no tack drape at room temperature. A resin composition was obtained. The viscosity-temperature characteristic of this resin composition was measured by the same method as in Example 1. The results are shown in Table 1.

When a prepreg was prepared from the above resin composition using a mixed solvent of methylene chloride / chloroform / methanol in the same manner as in Example 1, a prepreg having no tack drape at room temperature was obtained. Using this prepreg, the damaged area after the falling weight impact test was measured by the same method as in Example 1. The results are shown in Table 1.
Also, almost no resin flow was observed from the composite material after molding.

Comparative Example 2 Epoxy A 50 parts, Epoxy B 20 parts, Epoxy C30
The viscosity-temperature characteristic was measured in the same manner as in Example 1 with respect to the resin composition consisting of 1 part and 46 parts of diaminodiphenyl sulfone. The results are shown in Table 1.

100 parts of the above resin composition was added to methyl ketyl ketone 150
To prepare a homogeneous solution. A composite material having a thickness of about 5 mm was obtained from this solution by the same method as in Example 1. After molding, a noticeable resin flow was seen from the composite. Using this composite material, the damaged area after the falling weight impact test was measured by the same method as in Example 1. The results are shown in Table 1.

Comparative Example 3 Epoxy A 35 parts, Epoxy D 35 parts, Epoxy E30
The viscosity-temperature characteristic was measured in the same manner as in Example 1 with respect to the resin composition comprising 1 part and 34 parts of diaminodiphenyl sulfone. The results are shown in Table 1.

100 parts of the above resin composition was added to 150 parts of methyl ethyl ketone.
To prepare a homogeneous solution. A composite material having a thickness of about 5 mm was obtained from this solution by the same method as in Example 1. Using this composite material, the damaged area after the falling weight impact test was measured by the same method as in Example 1. The results are shown in Table 1.

Using the above resin composition, a unidirectional laminated material was produced in the same manner as in Example 1, and the tensile elongation at break in the fiber direction and the fiber orthogonal direction was measured. The results are shown in Table 1.

In addition, a remarkable resin flow was observed after molding from the composite material obtained in this example.

Comparative Example 4 Epoxy A 63 parts, Epoxy B 17 parts, Epoxy F22
The viscosity-temperature characteristic of the resin composition comprising 1 part and 45 parts of diaminodiphenyl sulfone was measured by the same method as in Example 1. The results are shown in Table 1.

100 parts of the above resin composition was added to 150 parts of methyl ethyl ketone.
To prepare a homogeneous solution. With this solution,
A composite material having a thickness of about 5 mm was obtained in the same manner as in Example 1.
Using this composite material, the damaged area after the falling weight impact test was measured by the same method as in Example 1. The results are shown in Table 1.

Using the above resin composition, a unidirectional laminated material was produced in the same manner as in Example 1, and the tensile elongation at break in the fiber direction and the fiber orthogonal direction was measured. The results are shown in Table 1.

In addition, a remarkable resin flow was observed after molding from the composite material obtained in this example.

[Curing of the Invention] (1) Damage due to impact of the composite material is reduced.

(2) A resin composition having excellent heat resistance and water resistance is provided.

(3) A prepreg with stable quality and excellent tack drape can be manufactured.

(4) A homogeneous resin composition and cured resin can be obtained.

(5) It can be molded using an autoclave without requiring special conditions.

(6) The tensile breaking elongation in the direction perpendicular to the fibers of the unidirectional laminated material is improved, and a homogeneous multidirectional laminated material can be obtained.

(7) Since the minimum viscosity is increased and the resin flow due to molding is small, it is possible to mold a composite material having a uniform thickness.

Claims (1)

[Claims] 1. As an essential component, [A] N, N, N ', N'-tetraglycidyldiaminodiphenylmethane [B] N, N, O-triglycidylmetaaminophenol [C] bisphenol F type epoxy resin [D ] Diaminodiphenyl sulfone [E] General formula An epoxy resin composition for prepreg prepared by blending a polyether sulfone represented by