JPH0378406B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an epoxy resin composition that has excellent strength and impact resistance, has a low molding shrinkage rate, and has extremely low metal corrosivity. [Conventional technology] Epoxy resin has excellent adhesive properties, insulation properties,
Due to its moisture resistance and heat resistance, it has shown remarkable growth in recent years in its use as a coating material for electronic components. However,
Although epoxy resin is a high-strength material, it is brittle. Furthermore, when used as a coating material, stress is applied to the covered semiconductor element due to shrinkage during curing, and if the stress is large enough, it may lead to destruction of the element. As a countermeasure against this problem, it has been considered to blend rubber or modified rubber, or to use an epoxy resin composition in which epoxy resin is reacted with rubber in advance. [Problems to be Solved by the Invention] However, blending conventional rubber materials with epoxy resins may cause coating problems due to impurities, mainly metal ions, caused by the use of emulsifiers and coagulants contained in the rubber. Corrosion occurs on semiconductor lead wires (mostly aluminum wires). [Means for Solving the Problems] In view of the above situation, the present inventors have conducted intensive studies on an epoxy resin composition that has excellent strength and impact resistance, has low mold shrinkage, and is resistant to metal corrosion. As a result, we have arrived at the present invention. That is, the present invention relates to an epoxy resin composition comprising an epoxy resin and a rubbery copolymer with little metal corrosion obtained by special emulsion polymerization. [Structure of the Invention] Generally, most rubbery copolymers, particularly rubbery copolymers containing a diene component, are synthesized by emulsion polymerization. However, in ordinary emulsion polymerization methods, anionic activators containing alkali metals such as potassium and sodium as counterions are widely used as emulsifiers, and sodium chloride is also used as a coagulant in the process of separating the produced polymer latex. , calcium chloride, and other metal compounds are used.
For this reason, these metal ions remain in the polymer, and these metal ions can hardly be removed even if the polymer latex is coagulated and washed with water. As a result, the epoxy resin composition obtained by mixing a rubbery copolymer produced by the conventional emulsion polymerization method with an epoxy resin is highly corrosive to metals, and is suitable for use in high-reliability electronic components such as ICs and LSIs. It cannot be used. On the other hand, synthesis of rubbery copolymers by solution polymerization method can reduce the amount of metal ions in rubber, but generally only low molecular weight polymers (in most cases liquid rubber) can be obtained and the cost is high. . In contrast, the special emulsion polymerization method of the present invention uses a nonionic surfactant as an emulsifier when obtaining a polymer by emulsion polymerization, and emulsion polymerization is performed at a temperature below the cloud point of the nonionic surfactant. This is an emulsion polymerization method in which the obtained polymer latex is coagulated without using a coagulant by heating the obtained polymer latex to a temperature above the clouding point, and the following () to () are obtained using this method. By mixing any of the rubber-like copolymers mentioned above with an epoxy resin, an epoxy resin composition having excellent impact resistance, low mold shrinkage, and low metal corrosivity can be obtained. () As monomer units constituting the polymer, 1 to 20% by weight of monomers having epoxy groups, hydroxyl groups, carboxyl groups, or amino groups, 15 to 50% by weight of acrylonitrile, and 40 to 80% by weight of butadiene and/or isoprene. % functional rubbery copolymer (2) 1 to 20% by weight of a monomer having an epoxy group, hydroxyl group, carpoxyl group or amino group as a monomer unit constituting the polymer, alkyl (meth)acrylate and/or Or a functional rubbery copolymer consisting of 40 to 99% by weight of alkoxy(meth)acrylate and 0 to 30% by weight of other monomers copolymerizable with the above monomers (2) Monomers constituting the polymer 1-20% by weight of monomers having epoxy, hydroxyl, carboxyl or amino groups as units, 15-50% by weight of acrylonitrile, 20-60% by weight of butadiene and/or isoprene, alkyl (meth)acrylates and/or alkoxy Functional rubbery copolymer consisting of 5 to 65% by weight of (meth)acrylate. In the production of the copolymer used in the present invention, the nonionic surfactant used as an emulsifier is a substance that exhibits significant surface activity at low concentrations and does not ionize in an aqueous solution. Specifically, polyoxyethylene alkyl Examples include ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene oxypropylene block polymer, alkylsulfinyl alcohol, and fatty acid monoglyceride. The temperature at which clouding occurs for the first time when an aqueous solution of a nonionic activator is heated is called the cloud point, and is a unique phenomenon that occurs in an aqueous solution of a nonionic activator. Thermodynamically, the cloud point corresponds to the lower critical temperature (LCST). When the temperature of a nonionic activator aqueous solution with a certain composition is increased, cloudiness, or a phase separation phenomenon, appears at a temperature above the clouding point, and the homogeneous phase system separates into two phases: an aqueous phase and an activator phase. be. This can be said to be due to a decrease in the concentration of the nonionic active agent in the aqueous phase, or in other words, the active agent has become poorly soluble in water. In this way, at temperatures above the cloud point, nonionic surfactants become poorly soluble in water and lose their activity as surfactants. This corresponds to a separation step that lowers the polymer latex and coagulates the polymer latex. That is, when emulsion polymerization is carried out using a nonionic activator as an emulsifier, coagulation can be performed without using a coagulant by utilizing the cloud point phenomenon. As a result, the copolymer used in the present invention is completely free of metal ions entering from emulsifiers and coagulants due to the use of nonionic activators. The molecular weight of the rubbery copolymer used in the present invention is not particularly limited, and can be selected from liquid low molecular weight to high molecular weight polymers as required. As the epoxy resin that can be used in the present invention, in addition to bisphenol type epoxy resins, special epoxy resins such as novolak type epoxy resins, polyphenol type epoxy resins, alicyclic type epoxy resins, and rubber-modified epoxy resins can also be used. I can do it. The amount of the functional rubbery copolymer of the present invention incorporated into the epoxy resin composition is 1 to 100 parts by weight, preferably 1 to 50 parts by weight, and more preferably 2 to 30 parts by weight, based on 100 parts by weight of the epoxy resin. be. If it is less than 1 part by weight, impact resistance and mold shrinkage effects will not be achieved, and if it exceeds 100 parts by weight, volume resistivity, which is a characteristic of epoxy resin, will be impaired. When the epoxy resin composition of the present invention is used for curing, any curing agent may be used as long as it is a curing agent used for ordinary epoxy resins, and if necessary, silica, clay, stone, calcium carbonate, quartz powder may be used. , fillers such as kaolin, mica, sodium silicate, talc, calcium silicate, titanium compounds, and antimony compounds, pigments, and additives such as anti-aging agents can be blended. The composition obtained according to the present invention can be effectively used as a coating material for electronic parts, as well as an adhesive, an electrodeposition coating agent, a lining agent, a sealing agent, and various other molding materials. [Examples] The present invention will be specifically described below with reference to Examples, but the present invention is not limited by these. Examples 1 to 9, Comparative Examples 1 to 5 Emulsion polymerization was carried out at 20° C. in an autoclave with an internal volume of 20° C. using the emulsion polymerization recipe shown below. (Parts by weight) Butadiene 55 Acrylonitrile 35 Acrylic acid 10 Water 220 Polyoxyethylene nonyl phenyl ether ^*
1 5 Tertiary dodecyl mercaptan 0.2 Ammonium persulfate 0.25 Cyanated ether diethanolamine 0.15 (*1 Kao Soap Co., Ltd. Emulgen 920 Cloud point 82
℃) After reaching a polymerization conversion rate of 90%, 0.2 parts by weight of hydroxylamine sulfate per 100 parts by weight of monomer was added to stop the polymerization. Subsequently, after heating and recovering the residual monomer by steam distillation at about 70°C under reduced pressure, 2 parts by weight of alkylated phenol was added as an antiaging agent, and then the polymer latex was placed in a pressure tube. The latex was coagulated by heating to 110°C. Take out the generated crumb and wash it with water for 50 minutes.
It was dried under reduced pressure at ℃ to obtain a sample for evaluation of a rubbery copolymer. (Sample 1) Other samples shown in Table 1 were synthesized using the same recipe. (Samples 2 to 12) Blending with the epoxy resin was performed in the following manner. (Parts by weight) Epoxy resin ^* 100 Rubber-like copolymer 20 Silica powder 100 Diethylenetriamine 15 (*Epikote 152 manufactured by Ciel Chemical Co., Ltd.) Epoxy resin and rubber-like copolymer are kneaded with a 4' electric heated roll at 80℃, and then mixed uniformly. When the mixture was warmed up, silica powder was added and kneading was continued, and finally diethyltetramine was added. The obtained epoxy resin composition was crushed and heated to 160°C.
A molded plate was obtained by press molding for 30 minutes. Samples for bending tests and impact tests were obtained by cutting out the obtained molded plate (4 mm thick) using a milling machine. The metal corrosion properties in Table 2 were determined according to the following method. An epoxy resin composition containing a predetermined amount of rubbery copolymer was cured and molded into a size of 10×10 mm. Next, add a 2mm thick copper plate (JIS H3100) to 30x30mm.
It was cut into pieces, thoroughly polished with 100 mesh abrasive paper, and then degreased. On top of the 10 x 10 mm epoxy resin sample above,
The above copper plate was placed on top and placed in a 300 ml specimen bottle.
Place this specimen bottle in a gear oven at 80℃.
After leaving it for 24 hours, the copper plate was removed and the degree of corrosion was visually checked. As can be seen from Table 2, the epoxy resin compositions according to the present invention (Examples 1 to 9) have high strength, good impact resistance, low shrinkage during molding, and no metal corrosion. . This effect is particularly remarkable in rubbery copolymers having carboxyl groups. As a result, the epoxy resin composition according to the present invention is particularly useful for electronic components in casting, embedding, encapsulation, and sealing applications.

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Claims (1)

[Claims] 1. A functional compound containing a monomer having any one selected from epoxy groups, hydroxyl groups, carboxyl groups, and amino groups as monomer units constituting the polymer in 100 parts by weight of epoxy resin. A rubber-like copolymer obtained by using a nonionic activator as an emulsifier and carrying out emulsion polymerization at a temperature below the cloud point of the nonionic activator. An epoxy resin composition containing 1 to 100 parts by weight of a copolymer which is coagulated by heating latex to a temperature above the clouding point without using a coagulant. 2. The epoxy resin composition according to claim 1, wherein the functional rubbery copolymer is any one of functionalized rubbery copolymers () to () composed of the following monomers ( ) As monomer units constituting the weight body, 1 to 20% by weight of a monomer having an epoxy group, hydroxyl group, carboxyl group or amino group, 15 to 50% by weight of acrylonitrile, and 40 to 80% by weight of butadiene and/or isoprene. A functional rubbery copolymer () consisting of 1 to 20% by weight of a monomer having an epoxy group, hydroxyl group, carboxyl group or amino group as a monomer unit constituting the polymer, an alkyl (meth)acrylate and/or Functional rubbery copolymer (2) consisting of 40-99% by weight of alkoxy(meth)acrylate and 0-30% by weight of other monomers copolymerizable with the above monomers. Monomer units constituting the polymer. 1-20% by weight of monomers having epoxy, hydroxyl, carboxyl or amino groups, 15-50% by weight of acrylonitrile, 20-60% by weight of butadiene and/or isobrene, alkyl (meth)acrylates and/or alkoxy ( Functional rubbery copolymer consisting of 5 to 65% by weight of meth)acrylate.