JPH02103223A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the title resin useful as a material for civil engineering and construction, providing a cured material excellent toughness, flexibility and impact strength by using a bisphenol A type epoxy resin having a specific ratio of weight-average molecular weight and number-average molecular weight. CONSTITUTION:The aimed resin containing (A) an epoxy resin of bisphenol A type having 450-700 number-average molecular weight and a ratio (weight- average molecular weight/number-average molecular weight) of 1.3-3.0 and (B) a curing agent for epoxy resin shown by the formula HNR1-A-HNR2 [R1 and R2 are (cyclo)alkyl, aryl or aralkyl; A is bifunctional aliphatic group hydrocarbon which may contain substituent group].

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition, and more specifically, it relates to an epoxy resin composition that is excellent in elastic modulus, hardness, and heat resistance, and particularly has excellent toughness, such as The present invention relates to an epoxy resin composition useful as a matrix resin for civil engineering and construction materials, paints, lining materials, adhesives, electrical equipment molding materials, machine parts, jigs, and fiber reinforced composite materials (hereinafter abbreviated as FrtP).

[Prior art]

Conventionally, epoxy resins have excellent heat resistance, elastic modulus, hardness, and chemical resistance, and are widely used as matrix resins for composite materials, especially those containing reinforcing fibers such as aramid fibers, glass fibers, and carbon fibers. However, there are various problems depending on the purpose and method of use. For example, F
When used as a matrix resin for RP, there is a problem that the mechanical strength of FRP is insufficient, especially the toughness that affects impact properties, fatigue properties, etc. Therefore, when using epoxy resin as a matrix resin,
In order to impart flexibility and further improve mechanical strength, particularly toughness, hardening agents and flexibility imparting agents are added.

However, with such conventional methods, although the flexibility of the cured epoxy resin product can be improved to some extent,
A significant decrease in physical properties such as elastic modulus, hardness, and heat resistance, which are the original characteristics of cured epoxy resins, was observed, and for example, FR
Not only is it impossible to significantly improve the toughness of P, but also the chemical resistance and weather resistance.

A new problem arises in that water resistance and the like are also reduced.

On the other hand, JP-A-62-127317 discloses an epoxy resin composition for prepregs comprising at least two polyepoxy compounds, a high molecular weight epoxy resin, dicyandiamide, and/or a curing accelerator in the molecule. There is.

[Problem to be solved by the invention]

However, when such epoxy resin compositions are used as prepreg epoxy resin compositions, there are problems with tackiness, drape properties, resin flow properties, workability, storage stability, etc., and improvements are desired. was.

In order to improve this point, the present inventors first [contains a bisphenol A-based epoxy resin and an epoxy resin curing agent, and the bisphenol A-based epoxy resin has an epoxy equivalent of 190 or less and 40 parts by weight or less. "an epoxy resin composition characterized by having a total number average molecular weight of 600 to 1,300" (Japanese Patent Application No. 63-773)
No. 25).

This epoxy resin composition has excellent tackiness, drapeability, workability, and storage stability when used as a prepreg resin, but according to subsequent studies by the present inventors, this epoxy resin has Due to its high number average molecular weight and high melt viscosity, it does not necessarily have good tack and drape properties at room temperature or lower temperatures, and furthermore, its tack and drape properties change depending on the environmental temperature. It was found that these materials did not exhibit stable properties over a wide temperature range, and that there were some problems with mechanical properties such as toughness and flexibility.

The present invention was made in view of the above circumstances, and its purpose is to exhibit excellent tack and drape properties not only at high temperatures but also at room temperature or lower temperatures, and which also exhibits excellent tack and drape properties over a wide temperature range. The object of the present invention is to provide an epoxy resin composition that remains stable over a long period of time and provides a molded article with excellent mechanical properties such as toughness and flexibility.

[Means to solve the problem]

According to the studies of the present inventors, it has been found that the above object can be achieved by using an epoxy resin having a number average molecular weight in a specific range and a specific molecular weight distribution, and by using a specific epoxy resin curing agent. Ta.

That is, the epoxy resin composition of the present invention contains a bisphenol A-based epoxy resin and an epoxy resin curing agent,
The bisphenol A-based epoxy resin has a number average molecular weight of 450 to 700, and a ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight/number average molecular weight) of 1.
．． 3 to 3.0, and the epoxy resin curing agent has the following formula: (representing an optional divalent aliphatic hydrocarbon group).

The first bisphenol A-based epoxy resin used in the present invention
is characterized in that its number average molecular weight is in the range of 450-700, preferably 500-650. If the number average molecular weight is less than 450, the amount of low molecular weight components will be too large, resulting in poor tackiness and drape properties of the resulting prepreg.
Moreover, resin flowability increases during curing, and furthermore, physical properties, particularly toughness, of the cured product deteriorate, making it impossible to achieve the intended purpose of the present invention. In addition, when the number average molecular weight exceeds 700, good physical properties of the cured product including toughness can be obtained, but the tackiness and drape properties at room temperature decrease due to the lack of low molecular weight components, and at lower temperatures. The tackiness and drape properties deteriorate further, making it impossible to handle it as a prepreg.

The second feature of the epoxy resin used in the present invention is.

Ratio of weight average molecular weight to number average molecular weight (weight average molecular weight/
Number average molecular weight: 1.3~3.0, preferably 1.5~
It is within the range of 2.7.

Ratio of weight average molecular weight to number average molecular weight (weight average molecular weight ff
When the ratio (l/number average molecular weight) is less than 1.3, the amount of low molecular weight components becomes too large, resulting in the same drawbacks as when the number average molecular weight is less than 450. If the ratio of weight average molecular weight to number average molecular weight (weight average molecular weight/number average molecular weight) exceeds 3.0, the high molecular weight component will be too large and the number average molecular weight will be 700.
This is not preferable because the same result will occur if the value is exceeded.

The bisphenol A-based epoxy resin used in the present invention is, for example, Epicoat 828.10o1 manufactured by Yuka Shell ■.
It can be prepared by appropriately mixing 1004.1007.1009.1010 (trade name) and the like.

Furthermore, according to the studies of the present inventors, general formula (1)% formula%
(1) (wherein R and R2 represent an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and A represents a divalent aliphatic hydrocarbon group which may have a substituent) When an epoxy resin composition is prepared by using an epoxy resin curing agent together with the above-mentioned bisphenol A-based epoxy resin, a chain polymer is easily formed, and a cured epoxy resin product that is particularly excellent in toughness can be obtained. It was discovered that

In the structural formula of the secondary amine derivative represented by the general formula (1) used in the present invention, R1 is preferably a lower alkyl group (for example, having 1 to 6 carbon atoms).

In addition, total R1 and 82950 mol 1 or more, preferably 8
It is desirable that 0 mol% or more is an alkyl group.

Furthermore, among lower alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 3 carbon atoms are particularly preferable; if the number of carbon atoms is 7 or more, the hardness and heat resistance of the cured epoxy resin may decrease. come.

Further, in the secondary amine derivative represented by the above general formula (1), A is a divalent aliphatic hydrocarbon group which may have a substituent; Examples of hydrogen groups include alkylene groups having 1 to 5 carbon atoms, and examples of substituents include alkyl groups, aryl groups, halogens, and hydroxyl groups.

Specific examples of the secondary amine derivative represented by the general formula (1) will be illustrated below.

CH, NH Kai (1 □ foot NllCl!.

Cl5NH (CI + □ Soup supplementary CH.

C113NH rice H2 HCI+.

CH, NH<H, 3T-NHCH.

Cl3NH-(c)1. W.L.H.

I4H, NH rice 11-kichi → H et al. I5 C1+3 CH,NH-CII-CH□-NIIC2)1゜-・ Cl3NH-CH-CH, -CH2C7H.

CH3 CH,NH-C-CH2-N)ICH.

CI(.

CH3 Cl3NH-C)! 2-C-CH, -NHcI+.

H CH3N1(-CH-CI2-NIICI+.

rCl3NH(-CI(-CI, -N)IcI(3LI) As described above, the amine curing agent of the present invention has the general formula (I)
Although the secondary amine is represented by, it is also possible to use other conventionally known curing agents or reaction accelerators as described below in combination, if necessary.

The reason why the epoxy resin prepreg according to the present invention has excellent mechanical properties, particularly toughness and flexibility, as well as excellent work stability and storage stability, is not clear at present, but it is thought to be due to the following reasons.

(1) Since the curing agent of the present invention contains a secondary amine as a main component, it forms a linear molecular chain.

(2) Analysis using gel permeation chromatography (GPC) has revealed that such linear molecular chains are formed prior to the initial gelation of the curing reaction. The molecular chains and high molecular weight bisphenol A-based epoxy resin increase the chain molecular components in the cured product, improving toughness.

(3) Because high molecular weight and low molecular weight bisphenol A-based epoxy resins are appropriately blended, the manufactured prepreg exhibits suitable melt viscosity and stable and suitable tackiness and drape properties without temperature dependence. .

The epoxy resin curing agent used in the present invention is usually blended in an active hydrogen equivalent ratio of 0.6 to 1.4, preferably 0.8 to 1.2, per equivalent of the bisphenol A-based epoxy resin. If the active hydrogen equivalent ratio of the curing agent is less than 0.6 or greater than 1.4, the heat resistance and hardness of the epoxy resin curing agent will decrease, which is not preferable.

According to the present invention, the curing agent may be mixed with the bisphenol A-based epoxy resin either as it is or dissolved in a solvent, heated to room temperature or, for example, 50°C. As a solvent,
Ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), cellosolves (methyl cellosolve,
Ethyl cellosolve, etc.), amides (dimethylformamide, etc.) are preferred, and the curing conditions for the epoxy resin composition according to the present invention are usually 130°C for 2 hours, preferably 130°C.
After curing at 0°C for 2 hours, post-curing was performed at 180°C for 2 hours.

Furthermore, when preparing the epoxy resin composition of the present invention, reactive diluents such as olefin oxide, glycidyl methacrylate, styrene oxide, and phenyl glycidyl ether; phenols, tertiary amines, imidazoles, Hardening accelerators such as complex salts of boron trifluoride, pyrazoles, and aminotriazole; and fillers such as silica powder, aluminum powder, mica, and calcium carbonate may also be added. Usually, the amount of these additives used is 0 to 15% by weight for a reactive diluent, 0 to 5% by weight for a curing accelerator, and 0 to 70% by weight for a filler, based on the mixture of hardener and epoxy resin. %.

According to another aspect of the present invention, when it is desired to improve heat resistance etc. even at the cost of some toughness, another epoxy resin other than the bisphenol A-based epoxy resin may be added as an epoxy resin component to the whole epoxy resin. It can be contained in an amount of 50 parts by weight or less per 100 parts by weight of the resin. In this case, if the content of the functional epoxy resin exceeds 50 parts by weight, the toughness will be significantly reduced, which is not preferable.

As the other epoxy resin, one or more kinds of epoxy resins that are commonly available on the market can be selected and used.
For example, glycidyl ether-based epoxy resins (bisphenol A, F, S-based epoxy resins, novolac-based epoxy resins, brominated bisphenol A-based epoxy resins), cycloaliphatic epoxy resins, glycidyl ester-based epoxy resins, glycidyl amine-based epoxy resins. , heterocyclic epoxy resins.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Examples 1 to 6 In this example, as bisphenol A-based epoxy resins, Epicote 828 (epoxy equivalent weight 184 to 194, number average molecular weight 380), 1001 (epoxy equivalent weight 450 to
500, number average molecular weight 900), 1004 (epoxy equivalent weight 875-975, number average molecular weight 1600), 1007
(Epoxy equivalent weight 1750-2200, number average molecular weight 2
900), 1009 (epoxy equivalent 2400-3300
, number average molecular weight 3750) and 1010 (epoxy equivalent weight 3000-sooo, number average molecular weight 5500) (manufactured by Yuka Shell ■, trade name), and the compounds shown in Table 1 as curing agents were used. A matrix resin for prepreg was prepared by vR in the proportions shown below.

In Example 6, Epikote 152 (epoxy equivalent: 172 to 179, number average molecular weight: 3
70) (manufactured by Yuka Shell ■, trade name) was added in an amount of 20 parts by weight.

In each example, 1 epoxy resin component shown in Table 1 was added.
The mixture was heated and mixed at 50°C. This mixture was cooled to 80° C., and a stoichiometric amount of an epoxy resin curing agent prepared at the compounding ratio shown in Table 1 was added to prepare an epoxy resin composition having high toughness at room temperature.

This was poured into a mold consisting of two glass plates and a Teflon spacer, heated at 100°C for 2 hours, then further heated to 200°C.
It was heated in an oven for 2 hours to cure.

The epoxy resin cured product thus obtained is 30 cm
A test piece was cut out from a resin casting plate measuring 30 cm x 3 mm, and its Izod impact strength (IZOD) was measured. The results are shown in Table-1. This material has heat resistance,
It was an epoxy resin with particularly excellent toughness.

In addition, carbon fibers with the epoxy resin obtained above aligned in one direction (strength 350 kg 10 I! 1, elastic modulus 32 t/mm2
) to obtain prepreg. It was found that this prepreg had excellent tackiness, and the tackiness did not change even in the temperature range of 15 to 30°C, indicating that there was no temperature dependence of tackiness. This was laminated for 12N and heated under the above-mentioned curing conditions to obtain a molded body. Post-impact compressive strength (CA
The results of measuring I) are shown in Table 1.

The epoxy resin compositions shown in Examples 1 and 2 had low viscosity and good workability during prepreg production.

In addition, the composition of Example 3.4 has good workability during production, and also has good properties as a prepreg such as tackiness, drapeability, resin flowability, handlingability, and storage stability.
there were. The composition of Example 5 was suitable as an epoxy resin for machined parts.

The composition obtained in Example 6 was an example in which a novolac type resin was blended, and the resin physical properties and prepreg properties were good like the others.

Comparative Examples 1 to 8 Epoxy resin compositions, prepregs, etc. were prepared and tested in the same manner as in the above examples using the formulation ratios shown in Table 1.The results are shown in Table 1.

From Table 1, it can be seen that the prepregs obtained in each comparative example had poorer tackiness, tack stability (temperature dependence of tack), storage stability, and toughness than the products of the present invention.

In addition, the symbols of the curing agent in Table 1-1 indicate the following.

(A) C turtle NH < H Kichi E turtle (B) c, H, NH-$ Horse soup M to H9 (C) (A
) / dicyandiamide = 50150 (D) dicyandiamide Also, the temperature dependence of the tackiness of prepregs using the epoxy resin composition according to Example 2, the epoxy resin composition of Comparative Example 5, and the epoxy resin composition of Comparative Example 7 as matrix resins. Data regarding sex are shown in the drawing.

From the drawings, it can be seen that when the number average molecular weight of the epoxy resin and the ratio of the weight average molecular weight to the number average molecular weight are outside the range of the present invention, as in Comparative Example 5, the tack value decreases as the temperature rises, and the tackiness of the prepreg becomes extremely high. It can be seen that the operability is poor because the temperature changes to . Furthermore, when the number average molecular weight of the epoxy resin exceeds 700 as in Comparative Example 7, even if the weight average molecular weight and number average molecular weight are within the range of 1.3 to 3.0, the prepreg deteriorates as the temperature rises. It is understood that the prepreg becomes hard and the handleability of the prepreg deteriorates.

In contrast, the tack value of the prepreg using the epoxy resin matrix of the present invention (Example 2) remains within the appropriate level of 200 to 300 g even when the temperature changes, and its storage stability and workability are It can be seen that the results are good.

The tack value is determined by cutting a sample of paper coated with molten resin to a thickness of about 30 μm onto a 10W strip.
This tack measuring device (Pikmatack manufactured by Toyo Seiki)
The sample was fixed to two upper and lower sample holders, pressed for a few seconds, and then peeled off at a constant speed (20 mm/min), and the stress at that time was taken as the tack value of the sample.

〔Effect of the invention〕

The epoxy resin composition according to the present invention has heat resistance, elastic modulus,
In addition to being excellent in hardness and chemical resistance, it provides a cured product with particularly excellent toughness, flexibility, and impact strength, and is also excellent in breaking strength, cracking resistance against thermal shock, adhesion, and adhesion. In addition, prepreg containing this material shows excellent tack and drape properties not only at high temperatures but also at room temperature or lower temperatures, and these properties remain stable over a wide temperature range, making it easy to work with. The properties and storage stability are dramatically increased.

[Brief explanation of drawings]

The drawing is a graph comparing the tack value and tack stability (temperature dependence of tack value) of prepregs using the epoxy resin composition according to the present invention and the epoxy resin composition according to a comparative example as matrix resins. Patent applicant Toa Fuel Industries Co., Ltd.

Claims (1)

[Claims] (1) Contains a bisphenol A-based epoxy resin and an epoxy resin curing agent, and the bisphenol A-based epoxy resin has a number average molecular weight of 450 to 700, and the ratio of the weight average molecular weight to the number average molecular weight (weight average Molecular weight/
number average molecular weight) is 1.3 to 3.0, and the epoxy resin curing agent has the following general formula HNR_1-A-HNR_2 (wherein R_1 and R_2 are an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group). and A represents a divalent aliphatic hydrocarbon group which may have a substituent.