JPS6250361A - Epoxy resin composition and production thereof - Google Patents

Abstract

PURPOSE:To lower the internal stress of the compsn. and to improve impact resistance as well as resistance to heat, weather and moisture and electrical characteristics, by uniformly dispersing fine particles of a polymer having a glass transition temp. of lower than room temp. in an epoxy resin. CONSTITUTION:An epoxy resin compsn. contains fine particles of a polymer having a glass transition temp. of lower than room temp. As said polymer, a homopolymer as well as a copolymer can be used. If desired, a mixture of one or more homopolymers and one or more copolymers may be used. Typical examples of monomers which can be used in the production of the polymers are (meth)acrylic esters. Other examples thereof are vinyl esters and vinyl ethers. The epoxy resin compsn. can be obtd. by polymerizing at least one monomer, which gives a homopolymer having a glass transition temp. of lower than room temp., in an epoxy resin, or by mixing fine particles of the polymer with an epoxy resin under heating.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an epoxy resin composition and a method for producing the same, and more particularly to an epoxy resin composition containing fine particles of other polymers in the system and a method for producing the same. .

(Prior Art) Epoxy resins are used in a wide range of industrial fields, from paints, coatings, linings, castings, pottings, adhesives, to electronic materials, especially transistors, and semiconductor encapsulating materials.

This is because epoxy resin has the advantages of excellent mechanical properties, adhesive properties, and electrical properties, but at the same time has the disadvantage that the cured product has a high elastic modulus and low energy absorption ability, making it hard and brittle. There is. Furthermore, although curing is carried out at high temperatures, considerable internal stress is generated due to subsequent cooling, which can cause a decrease in adhesive strength in adhesives and defects such as voids and cracks in molded products. ing.

Therefore, it is important to impart toughness to the epoxy resin and how to reduce internal stress, which is the cause of deterioration of various physical properties. Regarding this point, many improvement methods have been studied in the past. One of these modification methods is a modification method using a low molecular weight liquid rubber. This is made by reacting and immobilizing rubber in an epoxy resin using the carboxyl groups at both ends of the rubber molecule.

This method certainly reduces internal stress and improves impact resistance. However, since rubber has double bonds in its molecules, there are problems with heat resistance, weather resistance, etc. Furthermore, the reduction in stress and the improvement in impact resistance are not fully satisfactory.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is to solve the above-mentioned difficulties in the conventional method of adding low molecular weight liquid rubber, and more specifically, to reduce internal stress, improve iU impact resistance, and improve heat resistance and The objective is to develop a means for obtaining an epoxy resin composition with extremely excellent weather resistance, moisture resistance, electrical properties, etc.

[Means for solving problems]

As a result of extensive research to solve the above-mentioned problems, the inventors of the present invention have found that the intended purpose can be achieved by allowing fine particles of a polymer whose glass transition temperature does not reach room temperature to exist in an epoxy resin. Having discovered this, and also developed a new method for producing such a composition, the present invention has now been completed.

That is, the present invention provides an epoxy resin composition characterized in that fine particles of a polymer whose glass transition temperature does not reach room temperature are present in the system, and an epoxy resin composition characterized in that the glass transition temperature of the homopolymer does not reach room temperature. The present invention relates to a method for producing an epoxy resin composition, which comprises polymerizing at least one type of monomer in an epoxy resin.

[Structure and operation of the invention]

In the epoxy resin composition of the present invention, fine particles of a regular polymer (hereinafter referred to as the present polymer) whose glass transition temperature (hereinafter referred to as Tg) does not reach room temperature are present in the epoxy resin, preferably almost uniformly dispersed. It is something. In this case, the polymer of the present invention includes not only homopolymers but also copolymers, and these homopolymers and copolymers may be present as a mixture of one or two types. good.

The polymer used in the present invention has a Tg that does not reach room temperature, that is, does not reach 25°C, and is higher than room temperature, in order to impart flexibility to the epoxy resin and reduce internal stress at a rate of 9 J. If the material has a Tg, the thermal stress absorption and relaxation tlJJ effects that are the object of the present invention cannot be sufficiently achieved.

The Tg of the polymer defined here refers to a value that is measured with a differential calorimeter or the like and is known for each individual polymer.

However, these Tg values usually have an average degree of polymerization of at least 1.
Although the measurements were made for a polymer having an average degree of polymerization of 100 or more, it is also possible to use a polymer having an average degree of polymerization of 100 or less in the present invention.

A representative example of the monomer to form the polymer of the present invention is (meth)acrylic acid ester. At this time (
As the meth)acrylic ester, commonly used acrylic esters and methacrylic esters are used. Specific examples of this acrylic ester include alkyl groups such as methyl, ethyl, n-propyl, linear and branched butyl, amyl, hexyl, octyl, cyclohexyl, and 2-ethylhexyl. Acrylic acid alkyl esters are preferred. Moreover, a phenyl group can be exemplified as a group other than an alkyl group. Specific examples of methacrylic acid esters include linear and branched alkyl groups having 4 to 12 carbon atoms, such as butyl, isobutyl, hexyl,
In addition to methacrylic acid alkyl esters such as cyclohexyl group, isohexyl group, octyl group, dodecyl group, octadecyl group, and undecyl group, octadecyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid whose I11 chain is linear or branched. Preferred examples include hydroxyethyl. Also, methacrylic acid phenyl ester can be used.

In addition, when using methyl methacrylate, ethyl methacrylate, and propyl methacrylate, if only these are used, the Tg of the methacrylate ester resin produced will be higher than room temperature.
These methacrylic acid esters whose Tg is higher than room temperature lower the elastic modulus of the entire cured product and are less effective in reducing internal stress, so they are not particularly preferred in the present invention.

Further, in the present invention, monomers other than (meth)acrylic acid esters can also be used. For example, vinyl esters other than the above-mentioned (meth)acrylic acid esters, vinyl ethers, vinyl sheaides, vinyl amides, etc. can be used, and vinyl pyrrolide, acrylic alcohol, etc. can also be used. Examples of vinyl esters other than (meth)acrylic acid esters include vinyl acetate, vinyl fluohionate, vinyl butyralate, etc., and examples of vinyl ethers include alkyl vinyl ethers. Preferred examples of alkyl in this case include methyl, ethyl, propyl, butyl, amyl, hexyl, and the like. Examples of vinyl sheaides include methacrylonitrile, maleic dinitrile, vinylidene dianiide, etc.; examples of vinylamides include (meth)acrylamide and alkyl substituted (meth)acrylamide; more specifically, N-methylacrylamide. , N-methylmethacrylamide, N,N-dimethylacrylamide, and the like.

In the present invention, these monomers may be used alone or in combination of two or more.

As the polymerization initiator used in the polymerization of the above-mentioned monomers, various types conventionally used in the polymerization of (meth)acrylic acid ester resins can be used.

Specific examples include azo compounds such as azobisbutyronitrile, polymerization initiators that generate radicals upon heating such as peroxides such as benzoyl peroxide and lauroyl peroxide, and ketones such as benzoyl and dibenzyl ketone. and apolymerization initiators that generate radicals upon irradiation with ultraviolet rays, such as azo compounds such as abbiscyanovaleric acid.

The epoxy resin that is the object of the present invention is not particularly limited, and various known compounds containing two or more epoxy groups in one molecule can be widely used. The preferred epoxy 4) 1 resin usually has an epoxy equivalent of 50
-5000, more preferably about 100-3000 equivalents, softening point below room temperature - 200°C, preferably below room temperature - 15
The temperature is about 0°C.

The epoxy resins include those that are flat at room temperature to those that are solid at room temperature. Specific examples include glycidyl ethers of phenols such as bisphenol A1 bisphenol F, resorcinol, phenol novolak, and taredur novolac, and glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol.

As curing agents for such epoxy resins, acid anhydrides,
Any of various known epoxy resin curing agents can be used, including phenols and polyamides.

In addition, various curing accelerators known for use in epoxy resins can be used together with the curing agent, and particularly preferred examples include 2,4°6-tris(dimethylaminomethyl)phenol and 2-methylimidazole.

There are two methods for producing the epoxy resin composition of the present invention. One method is to prepare the polymer of the present invention in advance and add it to an epoxy resin while heating it.The other method is to polymerize monomers in the epoxy resin. This is a method of forming a polymer.

First, for the first method, fine particles of a homopolymer or (and) copolymer obtained by polymerizing one or more of the above monomers by various conventionally known polymerization methods, such as bulk polymerization method, etc. are mixed into the epoxy resin under heat.

The heating temperature at this time is usually 50 to 200°C, preferably 6°C.
The temperature is about 0 to 120°C.

In the second method, one or more of the above monomers are monopolymerized or copolymerized in an epoxy resin in the presence of a polymerization initiator if necessary. The polymerization conditions at this time may be appropriately selected depending on the type of monomer used, etc. The polymerization initiator used here is tR(i
It is preferable to use a material that dissolves in both the T-body and the epoxy resin.

Further, fillers such as quartz glass powder, silica stone powder, talc, and other various additives may be added to the resin composition according to the present invention, if necessary.

In the present invention, when blending polymer fine particles with an epoxy resin to obtain an epoxy resin composition that is the object of the present invention,
The particles may be thoroughly mixed with an epoxy resin, and if necessary, a curing agent and other additives may be added and kneaded.

In the epoxy resin composition of the present invention thus obtained, fine polymer particles are uniformly dispersed in the epoxy resin. For example, when a cross-section of a cured product obtained without using a filler component is observed with a scanning electron microscope, the dispersed state is recognized as a so-called "sea-island structure" in which the fine particles are present in the form of islands. The polymer particles have a diameter of 100 μm or less, preferably 0.05 to 50 μm, and are relatively monodisperse.

The content of the polymer particles present as a dispersed phase in the resin composition of the present invention is 3 to 3 parts by weight based on 100 parts by weight of the epoxy resin.
1 part by weight of 120ffi, particularly preferably 5 to 60 parts by weight.

The reason is that if it is less than 3 parts by weight, the effect of reducing thermal stress is insufficient, and if it exceeds 120 m1 part, the epoxy resin becomes a discontinuous phase. In either case, a resin composition excellent in low stress, impact resistance, moisture resistance, adhesiveness, and electrical properties as desired cannot be obtained.

The epoxy resin composition of the present invention can be effectively used in a wide range of applications in which various conventional epoxy resins are used, such as adhesives, paints, cast products, and electronic materials. A particularly preferred use is as a composition for semiconductor encapsulation.

〔Effect of the invention〕

In the present invention, fine polymer particles whose Tg does not reach room temperature exist uniformly dispersed in an epoxy resin, and the fine polymer particles exist as a dispersed phase and the epoxy resin exists as a continuous phase. forming an island structure. For this reason, the effect of reducing internal stress is fully exhibited, and the excellent properties inherent to epoxy resins are not impaired.

〔Example〕

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples; however, the present invention is not limited to these Examples.

Examples 1 to 5 Each component with the composition shown in Table 1 below was put into a 500m+2 round bottom flask and stirred at 150°C for 6 hours. cloudy,
A modified epoxy resin in which fine particles of (meth)acrylic acid ester resin were dispersed in an epoxy resin was obtained. The epoxy resin used here was bisphenol A epoxy resin (
Molecular weight: 380, epoxy weight: N190±5). These were mixed according to Table 2 to prepare a cured product.

The curing conditions were 80° C. for 2 hours and then 180° C. for 4 hours.

Examples 6 to 9 Using (meth)acrylic acid ester resins obtained by bulk polymerization at 70°C in a nitrogen atmosphere using benzoyl peroxide as a polymerization initiator, each component was prepared according to the composition shown in Table 2 below. It was treated in the same manner as in Example 1.

Comparative Examples 1 to 2 In Comparative Example 1, a methyl methacrylate-modified epoxy resin was prepared according to Table 3, and in Comparative Example 2, a resin was bulk polymerized at 70°C under a nitrogen atmosphere using benzoyl peroxide as a polymerization initiator. A cured product was produced in the same manner as in Example 1 using the obtained polymethyl methacrylate.

Comparative Example 3 According to Table 2, terminally carboxylated butadiene-acrylonitrile copolymer (carboxyl group content 2.4% by weight)
, butadiene:acrylonitrile copolymerization ratio 7:3) A cured modified epoxy resin was prepared.

Comparative Example 4 According to Table 2, a cured unmodified epoxy resin as a conventional example was prepared.

Regarding the examples and comparative examples produced above, mechanical properties (bending test, DIN-53453, impact resistance test, DIN-
53452), Internal Stress (Industrial Chemistry Magazine, ■, 110
8 (1958')), adhesive strength (ASTM
D1876-69T, D1002-69T), etc. were measured. The water absorption rate is the cured product (3X3X0.05CI1
1) Put the piece in 80℃ water for 24 hours? u? It was measured by R.

Table 1 Table 2 (Units: Weight RID Table 3) As shown above, the composition of the present invention can effectively lower the elastic modulus and reduce internal stress. The water resistance was also excellent in terms of water absorption. However, polymethyl methacrylate having a Tg of room temperature or higher did not have these effects.

According to the present invention, the epoxy resin in which a (meth)acrylic acid ester resin is present in the system can improve the defects without sacrificing the excellent physical properties of the cured epoxy resin.

(that's all)

Claims (5)

[Claims] (1) An epoxy resin composition characterized in that fine particles of a polymer whose glass transition temperature does not reach room temperature are present in the system. (2) Claim 1 in which the above polymer is a copolymer
The epoxy resin composition described in . (3) The epoxy resin composition according to claim 1, wherein the polymer is a mixture of two or more types of polymers or (and) copolymers. (4) The epoxy resin composition according to claim 1, characterized in that at least one monomer whose homopolymer glass transition temperature does not reach room temperature is polymerized in an epoxy resin. How things are made. (5) The method for producing an epoxy resin composition according to claim 1, characterized in that fine particles of a polymer whose glass transition temperature does not reach room temperature are added and mixed into the epoxy resin under heating.