JPH04332722A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide the subject composition composed of an epoxy resin, a glycidyl group-containing acryl polymer and an aromatic secondary diamine, capable of producing a cured material having a high toughness while maintaining its elasticity, i.e., resin strength and suitable for a molding material, an adhesive, etc. CONSTITUTION:The objective composition obtained by blending (A) an epoxy resin (preferably bisphenol A type epoxy resin) with (B) a glycidyl group- containing acryl polymer and (C) an aromatic secondary diamine as a curing agent. As the component (B), a terpolymer between butyl acrylate, glycidyl methacrylate and acrylonitrile, having >=300g/eq epoxy equivalent and 3000-20000 number-average molecular weight is preferable. As the component (C), p,p'-(N,N'- dimethyl)diaminodiphenyl sulfone is preferable and diaminodiphenyl sulfone as an aromatic primary diamine is preferably used in combination therewith in a molar ratio of (30:70)-(70:30).

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an epoxy resin composition that provides a cured product with excellent toughness.The cured epoxy resin composition has excellent heat resistance, chemical resistance, and electrical resistance due to its crosslinked structure. Because of its excellent performance in terms of mechanical properties and adhesion, it can be used as an adhesive for printed wiring boards, insulating impregnated materials for electrical equipment, molding materials such as sealants, automobile parts, aircraft parts, civil engineering and construction, etc. The composition of the present invention is used effectively in a wide range of industrial fields such as anti-corrosion and civil engineering/architectural paints.

0002

[Prior Art] As mentioned above, epoxy resins are widely used as molding materials, adhesives, coating materials, etc. However, on the other hand, the cured products of conventional resin compositions are hard and brittle, so 1) Impact Mechanical strength against etc. is low. 2) Cracks are likely to occur due to thermal shock, etc. 3) Adhesion to the substrate decreases due to internal strain due to curing shrinkage. There are drawbacks such as.

[0003] In order to eliminate the above-mentioned drawbacks, flexibility-imparting agents such as glycidyl esters of long-chain fatty acids, polyols, and urethane prepolymers are used in combination to impart flexibility.
Studies have been conducted to impart toughness using liquid rubber blends such as butadiene-acrylonitrile copolymers having amino or carboxyl groups at the terminals or specific poly(meth)acrylic acid esters (JP-A-1-271419). .

0004

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, the flexibility of the cured epoxy resin is improved, but the heat resistance and chemical resistance are reduced, and the elastic modulus, that is, the resin strength itself is reduced. There was a problem. An object of the present invention is to provide an epoxy resin composition that maintains the elastic modulus of the cured product, that is, the resin strength, and has toughness such as fracture toughness.

[0005]

[Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present inventors added an acrylic polymer having a glycidyl group to an epoxy resin, and added an aromatic secondary diamine to the epoxy resin. It was discovered that the cured material had significantly improved fracture toughness while retaining its elastic modulus, leading to the completion of the present invention.

Specifically, the present invention relates to an epoxy resin composition characterized by comprising the following three components. (A) Epoxy resin (B) Acrylic polymer having glycidyl group (C) Aromatic secondary diamine

Epoxy resin The epoxy resin used in the present invention includes bisphenol A type epoxy resin obtained by reacting bisphenol A with epichlorohydrin, bisphenol F type epoxy resin obtained by reacting bisphenol F/epichlorohydrin, and tetrabromobisphenol A. Based on brominated epoxy resin, similarly novolak type epoxy resin,
Common examples include hydrogenated bisphenol A epoxy resin, glycidyl ester epoxy resin, glycidylamine epoxy resin, hydantoin epoxy resin, triglycidyl isocyanurate, aliphatic epoxy resin, and alicyclic epoxy resin. It is also possible to use two or more of these epoxy resins in combination. A preferred epoxy resin for the present invention is a bisphenol A type epoxy resin.

Acrylic polymers having glycidyl groups The acrylic polymers used in the present invention have alkyl groups such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. A polymer or copolymer whose main constituent monomer is an alkyl ester of acrylic acid or methacrylic acid [hereinafter also referred to as (meth)acrylic acid] having 1 to 10 carbon atoms,
Alternatively, it refers to a copolymer of these (meth)acrylic acid alkyl esters and other vinyl monomers, such as polymerizable vinyl monomers such as styrene, acrylonitrile, and methacrylonitrile.

The above-mentioned acrylic polymer can be converted into an acrylic polymer having a glycidyl group, that is, the introduction of a glycidyl group into the acrylic polymer can be carried out using glycidyl acrylate, glycidyl methacrylate, vinylbenzyl glycidyl ether, vinyl phenyl glycidyl ether,
This can be easily carried out by copolymerizing a polymerizable monomer having a glycidyl group, such as isopropenylphenyl glycidyl ether or methallylbenzyl glycidyl ether, with the above-mentioned (meth)acrylic acid alkyl ester.

[0010] In the present invention, the preferred acrylic polymer having a glycidyl group is
0 mol% or more and 90 mol% or less of butyl acrylate, and the epoxy equivalent of the polymer is 300 g/eq
or more, and furthermore, its number average molecular weight is 3000
Above, 20,000 or less.

Acrylic polymers having a glycidyl group that are particularly preferable for the present invention include butyl acrylate which is an alkyl acrylate ester, glycidyl methacrylate which is a polymerizable monomer having a glycidyl group, and other vinyl monomers. It is a terpolymer obtained by copolymerizing acrylonitrile, which has the above properties.

Aromatic secondary diamine In the present invention, an aromatic secondary diamine is used as a curing agent for the epoxy resin. Specific examples of aromatic secondary diamines include P,P'-(N,N'-dimethyl)diaminodiphenylsulfone (hereinafter referred to as MDS), P,P'-(
Examples include N,N'-dimethyl)diaminodiphenylmethane.

These diamines are obtained by (N,N'-dialkyl) substitution treatment of aromatic primary polyamines such as diaminodiphenylmethane, diaminodiphenylsulfone (hereinafter referred to as DDS), and metaphenylenediamine.

In the present invention, the aromatic secondary diamine is combined with a commonly used curing agent such as an aliphatic polyamine, a polyamide polyamine, an alicyclic polyamine, an aromatic primary diamine, a latent curing agent such as dicyandiamide/adipate dihydrazide, It is possible to use one or more of polyamine curing agents, acid anhydride curing agents, tertiary amine curing agents, imidazole compound curing agents, etc., and this combination is used to adjust the crosslinking speed and crosslinking density. This is the preferred method.

A preferred aromatic secondary diamine for the present invention is MDS, and a more preferred aromatic secondary diamine for the present invention is MDS.
A combination of DS and an aromatic primary diamine is particularly preferred, and a particularly preferred combination is a combination of MDS and DDS, which is an aromatic primary diamine, and the preferred molar ratio when used in combination is 30:7.
0 to 70:30.

〇Blending Ratio In the epoxy resin composition of the present invention consisting of the above three components, the preferred blending ratio of these three components is that the ratio of the epoxy resin to the acrylic polymer is 95% by weight.
:5 to 60:40. Next, a curing agent can be added as appropriate depending on the type of curing agent, but when using only the aromatic secondary diamine and aromatic primary diamine together, it is preferable to add an equivalent amount to the glycidyl group in the composition. .

Other additives The composition of the present invention may contain pigments, stabilizers, various inorganic substances, curing accelerators, thermosetting resins, thermoplastic resins, and other additives to the extent that the features of the present invention are not impaired. Additives such as fuel agents, defoamers, leveling agents, coupling agents, plasticizers, reactive diluents, and liquid rubbers can be used.

Method for Preparing Composition As a method for preparing the composition of the present invention, conventionally known methods for preparing epoxy resin compositions can be employed. For example, by mixing epoxy resin and acrylic polymer,
It can be easily prepared by heating and mixing and dissolving at 150°C, or by dissolving and mixing both in an organic solvent, then adding a curing agent and dissolving uniformly. The epoxy resin composition thus obtained can be heat-cured in the same manner as conventional epoxy resins to provide a cured product that has both good elastic modulus and toughness, which are the objectives of the present invention.

[0019]

[Function] Generally, in order to toughen a rubber-modified epoxy cured product, it is necessary to have a microphase-separated structure in which rubber particles are dispersed in a matrix, and to have good adhesion between the matrix and the rubber particle interface. This is necessary, and the mechanism of toughening through microphase separation includes absorption of fracture energy by rubber particles, and fracture due to plastic deformation of the matrix resin around the rubber particles, which occurs when force is applied to weaker rubber particles. It is thought that both energy absorption and absorption are involved.

When the cured product of the composition of the present invention was observed using a scanning electron microscope, it was found that the acrylic polymer was very well dispersed in the form of particles, which is why it is believed that the excellent effects of the present invention are exerted. However, in addition to the appearance, since the acrylic polymer has epoxy groups, it seems that the adhesive properties are improved by reacting to some extent with the epoxy resin. As a result, the crosslinking density of the epoxy resin was adjusted, the acrylic polymer became easier to deform, the plastic deformation of the epoxy resin near the acrylic polymer particles increased, and the ability to absorb fracture energy increased. It seems that the invention brought about excellent effects.

[0021]

[Examples] The present invention will be explained in detail with reference to Examples below, but the present invention is not limited to these Examples.

〇Measuring method of physical properties of cured product As indicators of resin elastic modulus, bending strength and bending elastic modulus are
Measured according to JISK-7203. In addition, as an index of resin toughness, fracture toughness (KIC) is
It was measured by the notch bending test method in accordance with 99.

〇Synthesis of acrylic polymer The acrylic polymer used in the examples was prepared by the following method. 1.5 mol of a mixture of n-butyl acrylate, glycidyl methacrylate, and acrylonitrile in a molar ratio of 70:20:10 was dissolved in 450 ml of toluene solvent, and 10 mol of azobisisobutyronitrile was added as an initiator. Mol%, dodecyl mercaptan as chain transfer agent 0.02
mol was added, and the reaction was carried out at 70°C for 20 hours. After the reaction was completed, the reaction solution was poured into a large amount of hexane, and the polymer was separated and dried. The epoxy equivalent of the polymer was appropriately measured using the hydrochloric acid-dioxane method and was found to be 488 g/e.
It was q. The composition of the polymer was determined from epoxy equivalent weight and elemental analysis, and the molar ratio of n-butyl acrylate, glycidyl methacrylate, and acrylonitrile was 62:25.
:13. The number average molecular weight was determined by GPC,
It was 7900 in terms of polystyrene. This polymer is hereinafter referred to as A-1. Similarly, the composition of the polymer was n-butyl acrylate, glycidyl methacrylate, and acrylonitrile in a molar ratio of 66:22:12, and an epoxy equivalent of 5.
61, a polymer with a number average molecular weight of 7,300 was synthesized. This polymer is hereinafter referred to as A-2.

〇Example 1 Bisphenol A type epoxy resin A as the epoxy resin
A mixture of 80 g of ER-331 (epoxy equivalent: 190: manufactured by Asahi Kasei Corporation), 20 g of the above-mentioned polymer A-1, and a mixture of curing agents DDS and MDS at a molar ratio of 67:33 was prepared as described above. Add an equivalent amount to the epoxy equivalent,
An epoxy resin composition was obtained. This composition was heated to 120°C x 1
It was cured for +180°C x 5 hours to obtain a cured product. Table 1 shows the characteristic values of this cured product.

[0025]

[Table 1]

〇Examples 2 to 6 The molar ratio of the curing agent in Example 1 was DDS:MDS=48:5.
A composition (Example 2) was prepared in the same manner except that 2 was changed.
A cured product was obtained. Table 1 shows the characteristic values of this cured product. Similarly, the molar ratio of the curing agent in Example 1 was changed using DDS.
: A composition (Example 3) in which the MDS = 33:67 was changed, 90 g of the epoxy resin of Example 1, 10 g of A-2 as the polymer, and a curing agent molar ratio of DDS:MDS = 48:52. Compositions (Example 4) were prepared and cured products were obtained. Table 1 shows the characteristic values of these cured products. Similarly, a composition (Example 5) in which the epoxy resin was changed to 80 g and the polymer A-2 to 20 g in Example 4, and the epoxy resin was changed to 7 g.
5g, and a composition in which Polymer A-2 was changed to 25g (Example 6)
) were prepared and the characteristic values of each cured product are shown in Table 1.

Comparative Example 1 A composition was obtained and cured in the same manner as in Example 1, without adding any polymer, but in which the curing agent DDS alone was added in an equivalent amount to 100 g of epoxy resin. The characteristic values of this cured product are also shown in Table 1.
Shown below.

Comparative Examples 2 to 3 In contrast to Comparative Example 1, 80 g of epoxy resin and polymer A-1 were used.
Comparative Example 2 is a composition in which the amount of DDS:MDS is changed to 20g, Comparative Example 3 is a composition in which the molar ratio of the curing agent is changed to DDS:MDS=33:67 in Comparative Example 1, and the characteristic values of each cured product are are shown in Table 1.

[0029]

[Effects of the Invention] The epoxy resin composition of the present invention provides a cured product with excellent elastic modulus and toughness, and can be effectively used in a wide range of fields such as molding materials, adhesives, and coating materials. can.

Claims (1)

[Claims] 1. An epoxy resin composition comprising the following three components. (A) Epoxy resin (B) Acrylic polymer having glycidyl group (C) Aromatic secondary diamine