JPS6360056B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an epoxy resin composition for prepregs having excellent toughness, heat resistance, water resistance, and tuck/drape properties. [Prior art] Composite materials made of reinforcing materials such as carbon fibers, glass fibers, and aromatic polyamide fibers and epoxy resins are used for premium sports applications such as golf club shafts and fishing rods by taking advantage of their high specific strength and specific modulus. It is widely used as a structural material for aircraft, etc. However, the epoxy resins used in these composite materials have even greater strength, toughness, and
Performance is insufficient for applications that require heat resistance and water resistance. Currently, epoxy resins used in aircraft composite materials have 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, the resin composition has low 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 method is to add rubber such as acrylonitrile-butadiene copolymer to epoxy resin, and then cure the epoxy resin to form a rubber phase as a separate phase, which prevents cracks and increases adhesive strength. (For example, Japanese Patent Laid-Open No. 57-21450). Other methods include adding and mixing thermoplastic resins such as polyethersulfone, polysulfone, and polyarylate to epoxy resins to suppress the propagation of cracks in cured resins, and using these resins to create carbon fiber-reinforced composite materials. There are ways to improve toughness (e.g. THE BRITISH POLYMER
JOURNAL, Vo1.15, MARCH, 1983.P.71,
28th SAMPE SYMPOSIUM, 1983, P.367, Japanese Patent Application Publication No. 1983-134126). However, although the latter method does not impair the heat resistance and water resistance of the composite material, it is necessary to increase the amount of thermoplastic resin blended beyond a certain level in order to provide high toughness. When the amount of blended thermoplastic resin is increased, the viscosity of the epoxy resin becomes extremely high, which tends to cause poor impregnation and curing with reinforcing materials during prepreg manufacturing or molding processes, and impairs the tact and drape properties of the prepreg. Problems arise, such as making lamination work and molding of complex shapes impossible. [Problems to be Solved by the Invention] An object of the present invention is to provide prepregs with appropriate viscosity and appropriate tackiness and drape properties in the manufacturing process of resin compositions and prepregs for composite materials. An object of the present invention is to provide an epoxy resin composition for prepreg that has excellent toughness and heat resistance and water resistance. [Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. (1) Below, [A], [B], [C], [D] and [
E]
An epoxy resin composition for prepregs containing as an essential component. [A] N,N,N',N'-tetraglycidyldiaminodiphenylmethane [B] General formula Bisphenol A type epoxy resin represented by [C] Bisphenol F type epoxy resin [D] Diaminodiphenylsulfone [E] General formula Polyether sulfone represented by. However, in the above formula, n is 0.2 or less, and m is 20~
It is 500. In the present invention, n in the general formula [] of component [B] is preferably 0.20 or less, more preferably 0.10 or less. Further, m is preferably 20 to 500. N,N,N',N'-tetraglycidyldiaminodiphenylmethane used in the present invention is
It is commercially available under trade names such as ELM434 (manufactured by Sumitomo Chemical), MY720 (manufactured by Ciba-Geigy), and YH434 (manufactured by Toto Kasei). Since this epoxy resin is a tetrafunctional epoxy resin, it has the advantage that it has a high crosslinking density, and a cured product with high elastic modulus and high heat resistance can be obtained. However, it has the disadvantage that the cured product has low elongation and is brittle. Considering these characteristics,
The amount of N,N,N',N'-tetraglycidyldiaminodiphenylmethane added is 50% in the epoxy resin component.
~70% by weight is preferred. If the amount exceeds this range, the resulting cured product will become brittle and have poor water resistance. If the amount is decreased, the heat resistance and elastic modulus of the cured product will decrease. Therefore, in these cases, the toughness, heat resistance, and water resistance of CFRP decrease. The bisphenol A type epoxy resins represented by the general formula [I] used in the present invention are EP825 (manufactured by Yuka Ciel Epoxy Co., Ltd.), EP828 (manufactured by Yuka Ciel Epoxy Co., Ltd.), and DER331 (manufactured by Dow Chemical Japan Co., Ltd.). ) and are commercially available under product names such as In particular, from the viewpoint of improving tuck and drape properties, it is highly preferable to use EP825. Since the cured product obtained from this resin has a high resin elongation, it is very preferable for improving toughness, but on the other hand, since the modulus of elasticity is low, the amount added is 20 to 40% by weight in the epoxy resin component. The bisphenol F type epoxy resins used in the present invention are Epiclon 830 (manufactured by Dainippon Ink Chemical Industry Co., Ltd.) and Epicort 807 (manufactured by Yuka Ciel Epoxy Co., Ltd.).
It is commercially available under product names such as. Addition of this epoxy resin is very preferable because it lowers the viscosity of the epoxy resin composition for prepreg of the present invention and improves tack and drape properties. In addition, a compound having an appropriate viscosity can be obtained in prepreg manufacturing and molding processes, and workability can be greatly improved. However, although the cured product obtained from this epoxy resin has high resin elongation, it has slightly low heat resistance. Considering these characteristics, the amount of bisphenol F type epoxy resin added is 5 to 5% in the epoxy resin component.
20% by weight is preferred. Epoxy resins other than the epoxy resins used in the present invention include reactive diluents such as bisphenol S-type epoxy resins, phenol novolak-type epoxy resins, cresol novolak-type epoxy resins, and glycidyl derivatives of glycerin. , alicyclic epoxy resin, etc. However, if a large amount of these epoxy resins is used, the heat resistance, water resistance, tackiness and drape properties of the epoxy resin composition for prepreg of the present invention will be reduced, so the amount used is limited. The amount of the curing agent diaminodiphenyl sulfone used in the present invention may theoretically be 1 equivalent of amine per 1 equivalent of epoxy. In addition, depending on the curing speed, the preparation of the shelf life, and the heat resistance and water resistance of the resulting cured product,
The amount of this curing agent added is based on 1 equivalent of epoxy.
A preferred equivalent can be selected as appropriate within the range of 0.7 to 1.3 equivalents. Furthermore, boron trifluoride, amine complexes, imidazole compounds, dicyandiamide, and the like can also be used as curing accelerators. The polyether sulfone represented by the general formula [ ] used in the present invention was developed by Imperial Chemical Industries (UK),
It is commercially available under the trade name VICTREX. The amount of polyether sulfone added is preferably 15 to 30 parts per 100 parts of the epoxy resin for prepreg of the present invention. If the amount exceeds this range, the resulting resin composition will have a very high viscosity, resulting in poor resin impregnation and a prepreg with poor tack and drape properties. If the amount is less than this range, the effect of adding polyether sulfone will be small and the toughness will be low. In the present invention, it is of course possible to mix and use components other than [A] to [E] within the range that can exhibit the effect. There is no particular restriction on the method of mixing each component of the present invention,
A suitable method can be selected depending on the properties of the components and the mixing state or dispersion state of the target compound. As an example of the mixing method [A],
There is a method of making a homogeneous solution at a relatively low temperature using a solvent that dissolves each component of [B], [C], [D], and [E], and another example is a method of making a homogeneous solution at a relatively low temperature. There is a method of mixing each component at a high temperature. In the latter case, the epoxy resin and polyether sulfone are first melted at a relatively high temperature, and then the temperature is lowered.
A method in which a curing agent is then mixed is preferably used. The epoxy resin composition for prepreg of the present invention is
Although preferably used as a composite material resin, the carbon fibers used in this case can be applied to forms such as tapes, sheets, mats, textiles, etc. arranged in a certain direction. Furthermore, it can be used for reinforcing advanced composite materials such as aramid fibers, boron fibers, silicon carbide fibers, and hybrids thereof. [Function] In the present invention, bisphenol A type epoxy resin, bisphenol F type epoxy resin, diaminodiphenyl sulfone and polyether sulfone represented by N,N,N',N'-tetraglycidyldiaminodiphenylmethane are combined. By the way,
An epoxy resin composition for prepreg having excellent toughness, heat resistance/water resistance, and tack/drape properties is provided. Furthermore, a good composite material can be obtained without causing any inconvenience in the step of blending each component and the step of manufacturing a prepreg by impregnating it with a reinforcing agent. [Example] The present invention will be explained in more detail with the following example. The amount of each component in the examples represents parts by weight,
The contents of the epoxy resin are as follows. Epoxy A: N,N,N',N'-tetraglycidyldiaminodiphenylmethane, ELM434 manufactured by Sumitomo Chemical Co., Ltd. Epoxy B: Bisphenol A type epoxy resin, EP825 manufactured by Yuka Ciel Epoxy Co., Ltd. Epoxy C: Bisphenol F type Epoxy resin, Epiclon manufactured by Dainippon Ink Chemical Industries, Ltd.
830 Epoxy D: Bisphenol A type epoxy resin, Epicoat manufactured by Yuka Ciel Epoxy Co., Ltd.
828 Epoxy E: Brominated epoxy resin, manufactured by Dainippon Ink & Chemicals Co., Ltd. Epiclon 152 Epoxy F: Cresol novolak type epoxy resin, manufactured by Dow Chemical Japan Co., Ltd.
DEN485 Example 1 60 parts of epoxy A, 30 parts of epoxy B, epoxy
10 parts of C and 17.5 parts of polyether sulfone at 150℃
When heated and stirred, a clear viscous liquid was obtained after 30 minutes. When this composition was cooled to 60° C. and 46 parts of diaminodiphenylsulfone was uniformly dispersed, a resin composition having appropriate tack and drape properties at room temperature was obtained. When the above resin composition was cured at 180°C for 2 hours, a transparent cured resin product was obtained. The glass transition temperature of this cured resin (determined using a differential calorimeter at a heating rate of 40°C/min) is 212°C.
The water absorption rate (boiling/20 hours) was 2.9%. Similarly, a cured resin board was produced with the same composition as above without adding polyether sulfone. The glass transition temperature of this material is 212℃, and the water absorption rate is 3.3%.
It was hot. From this example, it was revealed that a cured resin product having excellent heat resistance and water resistance and in which polyether sulfone was homogeneously dispersed could be obtained. Example 2 The viscosity-temperature characteristics of the resin composition prepared in Example 1 were determined using a rheopexi analyzer (manufactured by Iwamoto Seisakusho, cone plate type) at a set temperature increase rate of 3° C./min. The minimum viscosity is shown in Table 1. 100 parts of the resin composition prepared in Example 1 was dissolved in 240 parts of a mixed solvent of methylene chloride/chloroform/methanol (53/43/4 weight ratio) to prepare a homogeneous solution. This solution is used as a trading card manufactured by Toray Industries, Inc.
A plain weave cloth using T300 was coated and impregnated with a resin content of 41% by weight. After air drying for one day, the solvent was removed by heat drying, and a homogeneous prepreg with appropriate tact and drape properties was obtained at room temperature. 24 sheets of this prepreg were laminated and heated at 180℃ for 2 hours using an autoclave at a pressure of 6.
It was cured under conditions of Kg/cm ² to obtain a composite material with a thickness of approximately 5 mm. Furthermore, almost no resin flow from the composite material was observed after molding. A falling weight impact energy of 680 kg cm/cm (sample thickness) was applied using a weight with a radius of 16 mm at the tip of this composite material. The damage caused by this impact test was measured using an ultrasonic flaw detection imaging device model M400B manufactured by Canon/Holosonics. The damaged area is shown in Table 1. Using the above resin composition, a resin film is formed on silicone paper, and this film is transferred to the unidirectionally aligned fibers of "Trading Card" T800 by heating and pressurizing so that the resin weight content becomes 35%. A homogeneous unidirectionally aligned prepreg with appropriate tack and drape properties at room temperature was obtained. 8 sheets of this prepreg were stacked and heated at 180℃ for 2 hours using an autoclave.
Cured under conditions of time and pressure of 6 kg/cm ² to a thickness of approx.
A unidirectional laminate of mm was obtained. Shimadzu Autograph
Using DCS-10T, the tensile elongation at break in the fiber direction of the composite material was measured at a crosshead speed of 1 mm/min. The results are shown in Table 1. In the same manner, 16 sheets of the above prepreg were stacked to obtain a unidirectional laminate with a thickness of about 2 mm. Shimadzu Autograph
Using IS-2000, the tensile elongation at break in the direction perpendicular to the fibers of the composite material was measured at a crosshead speed of 1 mm/min. The results are shown in Table 1. Example 3 60 parts of epoxy A, 20 parts of epoxy B, epoxy
For a system consisting of 20 parts of C, 17 parts of polyether sulfone and 46 parts of diaminodiphenylsulfone,
When a resin composition was prepared in the same manner as in Example 1, a resin composition was obtained that was uniform and had appropriate tack and drape properties at room temperature. A cured resin product was produced from this resin composition in the same manner as in Example 1, and a transparent cured resin product was obtained. This cured resin had a glass transition temperature of 215°C and a water absorption rate of 2.9%. Similarly, a cured resin board was produced with the same composition as above without adding polyether sulfone. This material had a glass transition temperature of 215°C and a water absorption rate of 3.3%. Example 4 The viscosity-temperature characteristics of the resin composition prepared in Example 3 were measured in the same manner as in Example 2. The minimum viscosity is shown in Table 1. Using the resin composition of Example 3, a homogeneous unidirectional prepreg having appropriate tuck and drape properties at room temperature was obtained in the same manner as in Example 2. Using this prepreg, the tensile elongation at break in the fiber direction and in the direction perpendicular to the fibers was measured in the same manner as in Example 2. The results are shown in Table 1. Further, after molding, almost no resin flow from the composite material was observed. A prepreg was prepared from the above resin composition in the same manner as in Example 2 using a mixed solvent of methylene chloride/chloroform/methanol, and this prepreg had appropriate tack and drape properties at room temperature. Using this prepreg, the damaged area after the falling weight impact test was measured in the same manner as in Example 2. The results are shown in Table 1. Furthermore, almost no resin flow from the composite material was observed after molding. Comparative example 1 60 parts of epoxy A, 30 parts of epoxy B, epoxy
A resin composition consisting of 10 parts of C, 40 parts of polyether sulfone and 46 parts of diaminodiphenylsulfone was prepared in the same manner as in Example 1, and a resin composition without tack and drape properties at room temperature was obtained. Comparative Example 2 A resin composition was prepared in the same manner as in Example 1 using a system consisting of 70 parts of epoxy A, 30 parts of epoxy D, 46 parts of diaminodiphenylsulfone, and 17 parts of polyether sulfone.
A resin composition with insufficient drapability was obtained. Comparative example 3 60 parts of epoxy A, 30 parts of epoxy B, epoxy
A resin composition consisting of 10 parts of C and 46 parts of diaminodiphenyl sulfone was prepared. This resin composition
A homogeneous solution was prepared by dissolving 100 parts in 150 parts of methyl ethyl ketone. A composite material having a thickness of approximately 5 mm was obtained from this solution in the same manner as in Example 2. After molding, resin flow from the composite material was observed. Using this composite material, the damaged area after the falling weight impact test was measured in the same manner as in Example 2. The results are shown in Table 1. Comparative example 4 35 parts of epoxy A, 35 parts of epoxy D, epoxy
The viscosity-temperature characteristics of a resin composition consisting of 30 parts of E and 34 parts of diaminodiphenylsulfone were measured in the same manner as in Example 2. The results are shown in Table 1. Add 100 parts of the above resin composition to methyl ethyl ketone.
A homogeneous solution was prepared by dissolving 150 parts. A composite material having a thickness of approximately 5 mm was obtained from this solution in the same manner as in Example 2. Using this composite material, the damaged area after the falling weight impact test was measured in the same manner as in Example 2. The results are shown in Table 1. A unidirectional laminate was produced using the above resin composition in the same manner as in Example 2, and the tensile elongation at break in the fiber direction and in the direction perpendicular to the fibers was measured. The results are shown in Table 1. Further, the composite material obtained in this example showed remarkable resin flow after molding. Comparative example 5 63 parts of epoxy A, 17 parts of epoxy B, epoxy
The viscosity-temperature characteristics of a resin composition consisting of 22 parts of F and 45 parts of diaminodiphenyl sulfone were measured in the same manner as in Example 2. The results are shown in Table 1. Add 100 parts of the above resin composition to methyl ethyl ketone.
A homogeneous solution was prepared by dissolving 150 parts. Using this solution, the same method as in Example 2 was used to obtain a film with a thickness of approximately 5 mm.
A composite of mm was obtained. Using this composite material, the damaged area after the falling weight impact test was measured in the same manner as in Example 2. The results are shown in Table 1. A unidirectional laminate was produced using the above resin composition in the same manner as in Example 2, and the tensile elongation at break in the fiber direction and in the direction perpendicular to the fibers was measured. The results are shown in Table 1. Furthermore, the composite material obtained in this comparative example showed significant resin flow after molding.

[Table] [Effects of the invention] (1) Damage to composite materials due to impact is reduced. (2) A resin composition with excellent heat resistance and water resistance is provided. (3) Prepreg with stable quality and excellent tack and drape properties can be produced. (4) A homogeneous resin composition and cured resin can be obtained. (5) Can be molded using an autoclave without requiring special conditions. (6) The tensile elongation at break in the direction perpendicular to the fibers of unidirectional laminated materials is improved, and homogeneous multidirectional laminated materials can be obtained. (7) Because the minimum viscosity increases and the resin flow during molding is reduced, it is possible to mold composite materials with uniform thickness.

Claims (1)

[Claims] 1. The following [A], [B], [C], [D] and [E]
An epoxy resin composition for prepregs containing as an essential component. [A] N, N, N', N'-tetraglycidyldiaminodiphenylmethane [B] General formula Bisphenol A type epoxy resin [C] Bisphenol F type epoxy resin [D] Diaminodiphenylsulfone [E] General formula Polyether sulfone represented by. However, in the above formula, n is 0.2 or less, and m is 20
~500. 2. An epoxy resin composition for prepregs, wherein n in general formula [I] of component [B] in claim 1 is 0.10 or less.