JPS62252417A - Resin composition for prepreg - Google Patents

Abstract

PURPOSE:To obtain the titled composition excellent in heat resistance, water resistance and moldability and suitable as a matrix resin for prepregs of FRP, by mixing a specified polyepoxy compound condensate with a cyanate resin and a thermoplastic resin. CONSTITUTION:0.01-0.6 equivalent of a curing agent such as an aromatic amine is added to a polyepoxy compound having at least two epoxy groups in the molecule, such as a bisphenol F-derived epoxy resin, and, if necessary, prereacted to obtain a polyepoxy compound condensate (A). 9-2pts.wt. component A is mixed with 1-8pts.wt. cyanate resin (B) comprising a polycyanate (a) of formula I (wherein m is 2-6, R is an aromatic organic group, and the cyanate group is bonded to the aromatic ring of the R group) or a mixture thereof with its prepolymer and a polymaleimide (B) of formula II (wherein R is a 2-6C aromatic or aliphatic organic group, X1-2 are each H, a halogen or an alkyl and n is m) or a mixture thereof with its prepolymer and 6-60wt%, based on the total of (a) + (b), thermoplastic resin which can homogeneously dissolve in both of components (a) and (b) (e.g., polyether sulfone).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel resin composition for prepreg. The cured resin obtained by the present invention has excellent heat resistance and water resistance, and is particularly suitable as a matrix resin for prepregs of fiber reinforced plastics (hereinafter abbreviated as FRP).

[Prior Art] Among curable resins, epoxy resins are widely used in various industrial fields due to their excellent mechanical properties. In particular, epoxy resins are often used in advanced composite materials made of reinforcing fibers such as carbon fibers, glass fibers, and aramid fibers and matrix resins. However, the epoxy resins used in these composite materials still have some unsatisfactory points, and their applications and usage methods are limited. One of them is heat resistance and water resistance. Various curable resins other than epoxy resins have conventionally been used as matrix resins to improve heat resistance and water resistance. Among these, cured products of cyanate ester resins have been known to provide cured products with excellent heat resistance and water resistance. However, since these cured products are brittle and have poor toughness, advanced composite materials using them as matrix resins lack impact resistance and have the disadvantage that they cannot fully exhibit the strength of reinforcing fibers.

In order to improve the toughness of these cured products, a method of adding an epoxy resin is known. In this case, the greater the amount of epoxy resin added, the higher the toughness, but the glass transition temperature (
Since To > was decreasing, it was necessary to newly add a curing agent for the epoxy resin. The curing agent used is generally an aromatic amine in consideration of heat resistance.

These resin compositions are known, for example, as shown in JP-A No. 60-25006.

However, when a composition is created by mixing these components, it has the drawback of high reactivity with polyfunctional cyanate esters and aromatic amines and a short pot life, making it difficult to use as a matrix resin for prepregs. there were.

Various improvements in toughness using Haku's method have also been investigated. For example, a cyanate ester resin composition is blended with a modified butadiene resin into which a meth (acryloyl) group has been introduced (Japanese Unexamined Patent Publication No. 57-153045), and one in which a butadiene-acrylonitrile copolymer is added (Japanese Unexamined Patent Application Publication No. 1983-153045). 5
7-153046), or by adding an epoxy resin to these, JP-A-56-157424.
56-157425) and the like are known.

However, all of these methods inevitably suffer from a decrease in heat resistance and water resistance.

There are other unsatisfactory points with the epoxy resins used as matrix resins for prepregs of composite materials. For example, lack of moldability is one of them. This is a problem caused by the following development.

Epoxy resin has great advantages as it becomes low in viscosity when heated to high temperatures, making it easier to impregnate reinforced l1ira during FRP molding, and making it easier for bubbles to form inside the molded product.However, on the other hand, if the viscosity is too low, When molding a large, thick molded product, the resin flows too much unnecessarily, causing problems such as disorder of reinforcing fibers and dimensional accuracy.

Therefore, there is a certain appropriate range of viscosity during molding.

However, if an attempt is made to increase the viscosity at high temperatures, the viscosity at room temperature will increase, resulting in a resin composition with poor tack and drape properties, making it unsuitable for practical use. This development is similar to the above-mentioned cyanate ester type.

In order to solve such problems, it is generally known to add a polymer to adjust the viscosity at high temperatures. Various types of polymers are known to be added, but if heat resistance is important, the polymer added should be as close to the glass transition temperature (
Those with a high Tg> are preferable and those that dissolve uniformly are preferable.

Furthermore, when considering the mechanical properties of the cured product, it is desirable that the polymer added has well-balanced mechanical properties.

Since many thermoplastic resins suitable for addition dissolve in solvents, there are concerns about the solvent resistance of the cured product to these solvents when added to epoxy resin compositions. When epoxy resin compositions containing thermoplastic resins are cured using various curing agents, those that dissolve uniformly and harden as they are, or those that do not dissolve uniformly and disperse finely even after phase separation, have very little solvent resistance. It turned out that there was no problem.

However, when cyanate ester resin is used, even if it is uniformly dissolved, the thermoplastic resin will undergo phase separation during the curing process, and because the dispersion is not fine, the final cured product will have poor solvent resistance and poor heat resistance. In many cases, the results were unsatisfactory. Even in this case, it was found that if a polyepoxy compound and its curing agent were used together, fine dispersion would be obtained even if phase separation occurred, and there would be almost no problem with solvent resistance.

However, as mentioned above, it has the disadvantage of high reactivity between polyfunctional cyanate esters and aromatic amines and short pot life, making it difficult to use as a matrix resin for prepregs.

[Problems to be Solved by the Present Invention] The purpose of the present invention is to add a thermoplastic resin to the cyanate ester resin for viscosity control in order to improve moldability, and to further improve the dispersibility of the cured product. The object of the present invention is to provide a resin composition for prepregs that does not shorten its pot life even when a polyepoxy compound containing an epoxy resin curing agent is used in combination to improve toughness.

[Means for Solving the Problems] As a result of intensive studies, the present inventors prepared an epoxy resin that had been pre-reacted with an equivalent amount or less of a curing agent, and prepared an epoxy resin that had been pre-reacted with an equivalent amount or less of a curing agent. When a resin composition with an epoxy resin curing agent added is created by adding a thermoplastic resin for viscosity control and a cyanate ester resin after reducing the concentration of the resin to a level that does not adversely affect pot life. However, the inventors have discovered that it is possible to provide a resin composition for prepregs that does not shorten pot life, has excellent heat resistance and water resistance, and has improved moldability, leading to the present invention.

That is, in order to achieve the above object, the present invention has the following configuration.

A single resin composition A containing at least the following components; A polyepoxy compound condensate B having at least two or more epoxy groups in one molecule, pre-reacted with an equivalent amount or less of a curing agent; Cyanic acid Ester Resin C: Thermoplastic Resin The polyepoxy compound used in the present invention can be used for most things without any restrictions. To specifically illustrate, Epicote 828. Liquid or solid bisphenol A epoxy resins such as Epicoat 1001 (manufactured by Yuka Shell Epoxy Co., Ltd.), DER-331 (manufactured by Dow Chemical Japan Co., Ltd.), ELM434. ), MY-7
Glycidylamine type epoxy resin such as 20 (manufactured by Ciba Geigi), bisphenol F type epoxy resin such as Epiclon 830 (manufactured by Dainippon Ink & Chemicals), Epicort 152. Phenol novolac type epoxy resins such as Epicoat 154 (manufactured by Yuka Shell Epoxy Co., Ltd.), brominated bisphenol A type epoxy resins such as Epiclo 152 (manufactured by Dainippon Ink Chemical Industries, Ltd.), ESCN
Examples include cresol novolac type epoxy resin such as -220 (manufactured by Sumitomo Chemical Co., Ltd.), other bisphenol S type epoxy resins, and alicyclic epoxy resins.

In addition, as an epoxy resin, thermoplastic resin is dissolved,
A resin having a low viscosity is preferable, and a bisphenol F type epoxy resin is particularly preferable.

These polyepoxy compounds may be used alone or in a mixture of several types without any problem.

Further, as the curing agent used in the preliminary reaction, any general curing agent for epoxy resins can be used, but as mentioned above, considering the purpose of use of the present invention, aromatic amines are preferable from the viewpoint of heat resistance. Examples include phenylene diamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiphenyl ether, and the like.

If these curing agents are added in an equivalent amount, they tend to cause gelation and are thermally unstable, so it is necessary to use less than that, but if the amount is too small, the effect will be reduced. It is preferably about 0.01 to 0.6 equivalent of the polyepoxy compound used, more preferably about 0.1 to 0.4 equivalent.

The preliminary reaction is achieved by simply adding a curing agent to the polyepoxy compound and leaving it for a certain period of time, but in reality, it is more efficient to accelerate the reaction to some extent by heating.

Further, the polyfunctional cyanate esters in component B are compounds having two or more cyanate ester groups, and preferred cyanate esters are compounds represented by the following general formula (1).

R-(-0-C3N>ll1(1) (in the formula, m is an integer of 2 or more and 6 or less, R is an aromatic organic group, and the cyanate ester group is Those bonded to aromatic rings: Specifically, dicyanatobenzene, tricyanatobenzene, dicyanatonaphthalene, tricyanatonaphthalene, diaminodiphenyl, bis(cyanatophenyl)methane, bis(cyanatophenyl)
Examples include propane, bis(cyanatophenyl) ether, bis(cyanatophenyl) sulfone, and cyanate ester obtained by reaction of novolac with cyanogen halide. It can also be used as a prepolymer obtained by polymerizing these polyfunctional cyanate esters in the presence of a catalyst such as a Lewis acid, a salt such as sodium carbonate, or lithium chloride.

Moreover, polyfunctional maleimides are compounds represented by the following general formula (2).

(In the formula, R is 2 to 6 aromatic or aliphatic organic groups, ×1. ×2 is hydrogen, halogen, or an alkyl group, and n is an integer of 2 to 6. ) The maleimides represented by the above formula can be obtained by reacting maleic anhydride with a polyamine having 2 to 6 amino groups to prepare maleamic acid, and then subjecting it to a dehydration reaction. The polyamine to be used is preferably an aromatic polyamine from the viewpoint of heat resistance, but an aliphatic amine may be used if flexibility and softness are desired to be imparted to the resin. Suitable amines include:
Examples include phenylene diamine, xylene diamine, cyclohexane diamine, diaminodiphenyl, diaminodiphenylmethane, diaminodiphenyl ether, diaminodiphenyl sulfone, and the like. Also used are condensation products of maleimide and these amines.

The mixing ratio of component A and component B varies depending on the type of compound used, but generally A:B is 9:1 to 2:8.
is within the range of

As mentioned above, various thermoplastic resins are known as component C, but if heat resistance is important, it is preferable that the polymer added has as high a glass transition temperature (Tg) as possible, and moreover, it is preferable to use a polyepoxy compound or cyanide. Preferably, those that dissolve uniformly in acid esters and maleimides.

When considering mechanical properties, it is desirable that the polymer added has well-balanced mechanical properties. Several types of thermoplastic resins can be used that satisfy such conditions.

Specific examples include polyether sulfone, polysulfone, polycarbonate, phenoxy resin, polyarylate, polyvinyl formal, polyvinyl butyral, and polyamide. The amount of these thermoplastic resins added is A
Preferably, it is about 6 to 60 parts per 100 parts by weight of the polyepoxy compound and the 8 components of cyanate esters and maleimide.If the amount is less than this, the addition effect will be small and if it is more than this, the tack and drape of the prepreg will deteriorate. Resulting in.

The method of mixing the components of the present invention is not particularly limited, and a preferred method can be selected as appropriate depending on the shape of each component and the mixing state or dispersion state of the intended blend. One example of a mixing method is to use a solvent that dissolves each component to form a homogeneous solution.Another example is to melt the polyepoxy compound and thermoplastic resin at a relatively high temperature without using a solvent, and then lower the temperature. There is a method of adding cyanate esters and maleimides.

In particular, the resin composition of the present invention is a useful epoxy resin composition that, when used as a matrix resin for FRP prepreg, provides a prepreg with excellent tack and drape properties, good moldability, and high toughness. However, the reinforcing fibers include carbon fiber, glass fiber, and aramid 4ii! Fibers, boron fibers, or hybrids thereof can be used. Moreover, any shape can be used, such as a tape arranged in a certain direction, a sheet-like material, a mat-like material, a woven material, etc.

Furthermore, various additives such as fillers, curing accelerators, and diluents can be used within the range that does not impair the properties.

[Function] In the present invention, an epoxy resin that has been pre-reacted with an equivalent amount or less of a curing agent is prepared in a resin composition, and the concentration of an amine that is highly reactive with polyfunctional cyanate esters is adjusted so that the pot life is not adversely affected. By adding a thermoplastic resin for viscosity control and a cyanate ester resin after reducing the viscosity to a certain level, even if a resin composition with an epoxy resin curing agent is created, the pot life will not be shortened. ,
It has now become possible to provide a resin composition for prepreg that has excellent heat resistance and water resistance, and has improved moldability.

[Example] The present invention will be explained in more detail by the following example. The amounts of each component in the examples represent parts by weight, and the contents of the resin are as follows.

Epoxy resin A: Tetraglycidyldiaminodiphenylmethane, 21M434 (Sumitomo Chemical Co., Ltd.) Epoxy resin B: Bisphenol F type epoxy resin, Epiclon 83
0 (manufactured by Dainippon Ink and Chemicals Co., Ltd.) BT resin: 2,2'-bis(4-cyanatophenyl)
Preliminary reaction product of propane, BT-216ORx (manufactured by Mitsubishi Gas Chemical Co., Ltd.) Example 1 5 parts of diaminodiphenylsulfone (DDS) was added to 1 part of epoxy resin A100ffiff, and a preliminary reaction was carried out at 130°C for 1 hour. Thereafter, 25 parts of polyether sulfone VICTREX 100P (manufactured by Company 1, C, I) having the following chemical structure was heated and stirred at 150'C, and a transparent viscous liquid was obtained after 30 minutes.

This mixture was cooled to 80°C, 100 parts of 8T resin was added, and the resin composition (q) was cast.
The mixture was cured for 2 hours to obtain a cured product.

The glass transition temperature (To) of this cured product was measured with a differential scanning calorimeter and was 210° C., indicating that it was a cured product with high heat resistance. Further, this cured product was immersed in methylene chloride and left for one day, but no change occurred.

The temperature dependence of the viscosity of this resin composition was measured using a Rheobexy Analyzer (manufactured by Kanmoto Seisakusho), and the minimum viscosity was 18 poise.

Example 2 10 parts of diaminodiphenylsulfone (DDS) was added to 8100 parts by weight of epoxy resin, and a preliminary reaction was carried out at 130°C for 1 hour. Then polyether sulfone vICTRE
When 25 parts of X100P (■, manufactured by C0■) were heated and stirred at 150°C, a transparent viscous liquid was obtained after 30 minutes. This mixture was cooled to 80°C and 100 parts of BT resin was added to obtain a resin composition. This resin composition was cast and cured at 180° C. for 2 hours to obtain a cured product.

The glass transition temperature (T(J)) of this cured product was measured with a differential scanning calorimeter and was 205°C, indicating that it was a cured product with high heat resistance.Also, this cured product was immersed in methylene chloride and left for one day. There was no change.

The temperature dependence of the viscosity of this resin composition was measured using a Rheobexie Analyzer (manufactured by Kanmoto Seisakusho), and the minimum viscosity was 23 poise.

Comparative Example 1 1 q of a resin composition was prepared in the same manner as in Example 1 except that the step of adding DDS and pre-reacting was removed.

This resin composition was cast and cured at 180° C. for 2 hours to obtain a cured product.

When the glass transition temperature (T!I+>) of this cured product was measured using a differential scanning calorimeter, it was 185°C, and the heat resistance was considerably lower than that of Example 1.

Furthermore, when this cured product was immersed in methylene chloride and left for one day, the surface turned white and began to crumble from the edges.

Comparative Example 2 A resin composition was obtained in the same manner as in Example 2 except that the step of adding DDS and pre-reacting was removed.

This resin composition was cast and cured at 180°C for 2 hours to obtain a cured product.

When the glass transition temperature (T(1>) of this cured product was measured using a differential scanning thermometer, it was 170° C., and the heat resistance was considerably lower than that of Example 2.

Further, when this cured product was immersed in methylene chloride and left for one day, the surface became white as in Comparative Example 1 and crumbled from the end surface.

Example 3 The resin composition prepared by 1q in Example 2 was left at room temperature for two weeks, but there was no significant change other than a slight increase in viscosity, and it was fully usable.

Comparative Example 3 A resin composition was obtained in the same manner as in Example 2 except that DDS was added to Ichiban@Shun instead of pre-reacting.

The resulting resin composition was left at room temperature for two weeks, but it became hard and had poor fluidity, making it unusable.

Example 4 When the cast resin plate obtained in Example 1 was cut out and its tensile properties were measured, the elongation at break was 3.7%. When the cast resin plate obtained in Example 2 was similarly cut out and its tensile properties were measured, the elongation at break was 4.9%.

Comparative Example 4 When a casting resin was prepared using only BT resin and its tensile properties were measured, the elongation at break was 1.5%, and compared to Example 4, it was considerably less flexible and brittle.

Comparative Example 5 Polyether sulfone VICTREX1 in Example 1
A resin composition was obtained in the same manner as in Example 1 except for the step of adding 25 parts of 00P (manufactured by Company 1, C, I).

The temperature dependence of the viscosity of this resin composition was measured using a Rheobexy Analyzer (manufactured by Script Seisakusho), and the lowest viscosity was 2 poise, which was considerably lower than that of Example 1.

Claims (3)

[Claims] (1) Resin composition A containing at least the following components; Polyepoxy compound condensate B having at least two or more epoxy groups in one molecule, pre-reacted with an equivalent or less amount of curing agent; Cyanide Acid ester resin C; thermoplastic resin (2) The resin composition for prepreg according to claim 1, wherein the thermoplastic resin of component C is polyallylether sulfone represented by the following general formula (Ar-SO_2)_n Ar; ▲ mathematical formula, chemical formula , tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ n is an integer of 5 or more (3) The cyanate ester resin of component B is (a) a mixture with a polyfunctional cyanate ester containing two or more cyanato groups in the molecule or a prepolymer thereof, or (b) a molecule with (a). The resin composition for prepreg according to claim 1, which comprises a polyfunctional maleimide containing two or more maleimide groups or a mixture thereof with a prepolymer.