Abstract:
A resin composition comprising 100 parts by weight of a thermosetting resin and 1 to 100 parts by weight of a functional, rubbery copolymer containing among the monomer units which constitute the copolymer, at least one monomer containing a substituent selected from the group consisting of epoxy, hydroxyl, carboxyl and amino groups, said copolymer being prepared by one of three emulsion polymerization processes in which a nonionic surface active agent and/or ionic surface active agent is employed as the emulsifying agent.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a thermosetting resin composition having a very low metal-corrosiveness, an excellent strength, an excellent impact resistance and a small molding shrinkage. 
     2. Description of Prior Art 
     In recent years, thermosetting resins have been used in a remarkably increased amount in the field of coating material for electronic parts because of their excellency in adhesion, insulation, moisture resistance and heat resistance. However, thermosetting resins are brittle, although they are high-strength materials. Also, when used as a coating material for electronic parts, they shrink during setting, and hence, stress is applied to the semiconductor elements coated by them. If the stress is large, the elements becomes fractured in some cases. 
     In order to solve the above problem, it has been tried to use a thermosetting resin composition obtained by blending a thermosetting resin with a rubber or a modified rubber or a rubber-modified thermosetting resin obtained by preliminarily reacting a thermosetting resin with a rubber. 
     However, when a thermosetting resin composition obtained by blending a thermosetting resin with a conventional rubber material is used for coating a semiconductor, metal ions and other impurities resulting from the emulsifier contained in the rubber material and from the use of a coagulant cause corrosion of lead wires (aluminum wires in many cases) of the semiconductor. 
     SUMMARY OF THE INVENTION 
     Under such circumstances, the present inventors have made extensive research on a thermosetting resin composition having a low metal-corrosiveness, an excellent strength and impact resistance and a small molding shrinkage. As a result, it has been found that a thermosetting resin composition consisting of (a) a functional, rubbery copolymer obtained by a special production process having a low metal-corrosiveness and (b) a thermosetting resin can solve the above-mentioned corrosion problem. 
     According to this invention, there is provided a resin composition comprising 100 parts by weight of a thermosetting resin and 1 to 100 parts by weight of a functional, rubbery copolymer containing as one of the monomer units constituting the copolymer at least one monomer having a group selected from the group consisting of epoxy, hydroxyl, carboxyl and amino groups, said copolymer being produced by one of the following methods: 
     (a) a method comprising subjecting the constituent monomers to emulsion polymerization using an emulsifier consisting of 1 to 15 parts by weight of a nonionic surface active agent and 0 to 10 parts by weight of an ionic surface active agent per 100 parts by weight of the monomers, the weight ratio of the ionic surface active agent to the nonionic surface active agent being 0-2.0:1, recovering unreacted monomers, adding a metal-free electrolyte to the resulting polymer emulsion, heating the resulting mixture to precipitate a polymer, optionally washing the polymer with water, and then drying the polymer, 
     (b) a method comprising subjecting the constituent monomers to emulsion polymerization using an ionic surface active agent as an emulsifier, recovering unreacted monomers, adding a metal-free electrolyte and a nonionic surface active agent to the resulting polymer emulsion, heating the resulting mixture to precipitate a polymer, optionally washing the polymer with water, and then drying the polymer, and 
     (c) a method comprising subjecting the constituent monomers to emulsion polymerization using a nonionic surface active agent as an emulsifier at a temperature lower than the cloud point of the nonionic surface active agent and then heating the resulting polymer latex to a temperature not lower than said cloud point to coagulate the latex without using any coagulant. 
     Synthesis of almost all rubbery copolymers, particularly rubbery copolymers containing a diene component, is usually conducted in accordance with an emulsion polymerization process. 
     In conventional emulsion polymerization processes, however, anionic surface active agents which contain, as the counter ion, an alkali metal such as potassium, sodium or the like are in general widely used as emulsifiers. Also, in the step of separating the polymer latex formed, a metal compound such as sodium chloride, potassium chloride or the like is used as the coagulant. These metal ions remain in the polymer formed and cannot be sufficiently removed even by coagulating the polymer latex and washing the same with water. Consequently, thermosetting resin compositions obtained by mixing a rubbery copolymer produced in accordance with a conventional emulsion polymerization process with a thermosetting resin have high metal-corrosiveness and hence cannot be used in electronic parts of high reliability such as IC and LSI. 
     Furthermore, in synthesis of rubbery copolymers according to a solution polymerization process, the amount of metal ions in rubber can be reduced; however, only a polymer having a low molecular weight is generally produced. Moreover, the production cost of polymer is high. 
     On the other hand, the functional rubbery copolymer used in this invention is produced by one of the following methods: 
     (a) a method comprising subjecting the constituent monomers to emulsion polymerization using an emulsifier consisting of 1 to 15 parts by weight of a nonionic surface active agent and 0 to 10 parts by weight of an ionic surface active agent per 100 parts by weight of the monomers, the weight ratio of the ionic surface active agent to the nonionic surface active agent being 0-2.0:1, recovering unreacted monomers, adding a metal-free electrolyte to the resulting polymer emulsion, heating the resulting mixture to precipitate a polymer, optionally washing the polymer with water, and then drying the polymer, 
     (b) a method comprising subjecting the constituent monomers to emulsion polymerization using an ionic surface active agent as an emulsifier, recovering unreacted monomers, adding a metal-free electrolyte and a nonionic surface active agent to the resulting polymer emulsion, heating the resulting mixture to precipitate a polymer, optionally washing the polymer with water, and then drying the polymer, and 
     (c) a method comprising subjecting the constituent monomers to emulsion polymerization using a nonionic surface active agent as an emulsifier at a temperature lower than the cloud point of the nonionic surface active agent and then heating the resulting polymer latex to a temperature not lower than said cloud point to coagulate the latex without using any coagulant. 
     When a thermosetting resin is blended with one of the following rubbery copolymers (I), (II) and (III) produced by the above polymerization methods, there is obtained a thermosetting resin composition having an excellent impact resistance, a small molding shrinkage and a low metal-corrosiveness: 
     (I) A rubbery copolymer comprising 1 to 20% by weight of at least one monomer having a group selected from the group consisting of epoxy, hydroxyl, carboxyl and amino group, 15 to 50% by weight of acrylonitrile and 40 to 80% by weight of butadiene and/or isoprene as the monomer units constituting the copolymer. When the acrylonitrile content is less than 15% by weight, this copolymer is insufficient in oil resistance, and when the acrylonitrile content exceeds 50% by weight, the copolymer has a reduced elasticity. The acrylonitrile content is preferably 25 to 45% by weight. When the butadiene and/or isoprene content is less than 40% by weight, the copolymer is insufficient in rubber elasticity, and when it exceeds 80% by weight, the copolymer has a poor compatibility with the thermosetting resins. 
     (II) A rubbery copolymer comprising as the monomer units constituting the copolymer 1 to 20% by weight of at least one monomer having a group selected from the group consisting of epoxy, hydroxyl, carboxyl and amino groups, 40 to 99% by weight of an alkyl(meth)acrylate and/or an alkoxyalkyl(meth)acrylate and 0 to 30% by weight of other monomers copolymerizable with these monomers (specifically, ethylidenenorbornene, dicyclopentadienyl acrylate, acrylonitrile, styrene or the like is added depending upon purposes). When the alkyl (meth)acrylate and/or alkoxyalkyl(meth)acrylate content is less than 40% by weight, this copolymer is insufficient in oil resistance and compatibility with the thermosetting resin. 
     (III) A rubbery copolymer comprising as the monomer units constituting the copolymer 1 to 20% by weight of at least one monomer having a group selected from the group consisting of epoxy, hydroxyl, carboxyl and amino groups, 15 to 50% by weight of acrylonitrile, 20 to 60% by weight of butadiene and/or isoprene and 5 to 65% by weight of an alkyl(meth)acrylate and/or an alkoxyalkyl(meth)acrylate. When the acrylonitrile content is less than 15% by weight, this copolymer is insufficient in oil resistance, and when it exceeds 50% by weight, the copolymer has a reduced elasticity. The acrylonitrile content is preferably 25 to 45% by weight. When the alkyl(meth)acrylate and/or alkoxyalkyl(meth)acrylate is less than 5% by weight, the copolymer is poor in weather resistance, and when it exceeds 65% by weight, the copolymer is poor in rubber elasticity. When the butadiene and/or isoprene content is less than 20% by weight, the copolymer is poor in rubber elasticity, and when it exceeds 60% by weight, the copolymer is poor in weather resistance. 
     In this invention, the monomer having a carboxyl group includes specifically acrylic acid, methacrylic acid, maleic acid and fumaric acid, and these may be used alone or in admixture of two or more. 
     The monomer having an epoxy group includes specifically glycidyl(meth)acrylate, allyl glycidyl ether and vinyl glycidyl ether, and these may be used alone or in admixture of two or more. 
     The monomer having a hydroxyl group includes specifically 1-hydroxypropyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, hydroxyethyl(meth)acrylate, and the like, and these may be used alone or in admixture of two or more. 
     The monomer having an amino group includes specifically monomers having a tertiary amino group such as dimethylaminoethyl(meth)acrylate, diethylaminoethyl(meth)acrylate, dibutylaminoethyl(meth)acrylate and the like, and these may be used alone or in admixture of two or more. 
     The alkyl(meth)acrylate includes specifically ethyl acrylate, ethyl methacrylate, propyl acrylate, butyl actylate, butyl methacrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, and the like, and these may be used alone or in admixture of two or more. 
     The alkoxyalkyl(meth)acrylate includes specifically ethoxyethyl acrylate, methoxyethyl acrylate, propoxyethyl acrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, butoxyethyl acrylate, butoxyethyl methacrylate, and the like, and these may be used alone or in admixture of two or more. 
     Alkyl(meth)acrylates and alkoxyalkyl(meth)acrylates having incorporated thereinto a functional group other than carboxyl, epoxy, hydroxyl and amino groups can also be used. Specific examples of these compounds are cyanoethyl(meth)acrylate, mercaptopropyl(meth)acrylate and 2-chloroethoxyethyl(meth)acrylate. 
     The nonionic surface active agents used as an emulsifier in the production of the functional, rubbery copolymer used in the resin composition of this invention are those having a remarkable surface activity at a low concentration but not ionizing in an aqueous solution. Specific examples of the nonionic surface active agent include polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene oxypropylene block polymers, alkyl sulfinyl alcohols and fatty acid monoglycerides, and the like. 
     These nonionic surface active agents can be used alone or in combination of two or more and are appropriately selected depending upon polymerization conditions and use purposes. The amount of the nonionic surface active agent used is 1 to 15 parts by weight per 100 parts by weight of the monomers. The nonionic surface active agent used has preferably a cloud point of 20° to 110° C. When the cloud point is too low, the latex formed has an insufficient stability, and when the cloud point is too high, a high temperature is required for coagulation of latex; therefore, too low or too high a cloud point is not practical. 
     In this invention, the ionic surface active agent is used together with the nonionic surface active agent to ensure the stability of latex during the recovery of unreacted monomers. The ionic surface active agent is, in this case, used in an amount of 0 to 10 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight of the monomers. When the amount exceeds 10  parts by weight, coagulation of latex is insufficient and such a large amount is not practical. In view of latex stability, an amount of 0.1 part by weight or more is preferred. 
     The weight ratio of the ionic surface active agent to the nonionic surface active agent must be 2.0 or less. When the weight ratio exceeds 2.0, an extremely high temperature is required during coagulation, or addition of a large amount of an electrolyte is required. Therefore, it is impractical. 
     The ionic surface active agent may be any of anionic surface active agents (e.g. sulfuric acid esters of higher alcohols, salts of alkylbenzenesulfonic acids, salts of aliphatic sulfonic acids), cationic surface active agents (e.g. dodecyltrimethylammonium chloride and the like) and amphoteric surface active agents containing a carboxylic acid salt, a sulfuric acid ester salt, a sulfonic acid salt or a phosphoric acid ester salt as the anionic portion and an amine salt or a quaternary ammonium salt as a cationic portion. These surface active agents can be appropriately selected depending upon use purposes. 
     When the nonionic surface active agent is used alone, a latex can be coagulated by heating it to a temperature not lower than the cloud point of the nonionic surface active agent. However, when the ionic surface active agent is used together with the nonionic surface active agent, the latex cannot be coagulated by only heating unlike the use of the anionic surface acture agent alone, and therefore, the latex is coagulated by adding an electrolyte thereto, stirring the resulting mixture and heating it, and the polymer separated is then taken out. In this process, the heating is the point and the mere addition of an electrolyte causes no coagulation. The amount of the electrolyte used may be varied depending upon the type of polymer and the type and amount of the surface active agent used in polymerization, though an amount of 5 to 20 parts by weight per 100 parts by weight of the polymer in a latex is sufficient. 
     As the electrolyte, preferred are amonium salts such as ammonium sulfate, ammonium chloride, ammonium nitrate, ammonium phosphate, ammonium acetate and the like, for the purpose of incorporating no metal ion. 
     As mentioned above, emulsion polymerization is conducted using the ionic surface active agent alone or in combination with the nonionic surface active agent to obtain a polymer emulsion, and the polymer emulsion is subjected to monomer recovery in a conventional manner, after which the electrolyte is added to the emulsion (the electrolyte and the nonionic surface active agent are added when polymerization is conducted using the ionic surface active agent alone), and the emulsion is then heated to precipitate a polymer which is then taken out. 
     When an aqueous solution containing the nonionic surface active agent mentioned above is heated, the solution begins to cloud at a certain temperature. This temperature is called cloud point. This is the phenomenon characteristic of aqueous solutions containing a nonionic surface active agent. The cloud point corresponds thermodynamically to a lower critical temperature (LCST). When an aqueous solution containing a nonionic surface active agent is heated, white turbidity, namely, a phase separation phenomenon appears at a temperature not lower than the cloud point of the nonionic surface active agent and a system having a single uniform phase is converted into a system having two phases, namely aqueous phase and surface active agent phase. 
     It can be said that this means that the concentration of the nonionic surface active agent in the aqueous phase has been reduced, and in other words, the surface active agent has become difficult to dissolve in water. 
     Thus, nonionic active agents are sparingly soluble in water at temperatures not lower than their cloud points and lose their activities as surfactants. This corresponds to a latex separation step wherein an acid or a polyvalent metal ion is added to an anionic surface active agent to reduce the water-solubility of the anionic surface active agent and to coagulate a polymer latex. That is, when a nonionic surface active agent is used as an emulsifier in emulsion polymerization, it is possible to coagulate the latex by utilizing the cloud point phenomenon of the nonionic surface active agent without using any coagulant. 
     Thus, the use of a nonionic surface active agent enables the copolymer used in this invention to be completely free of any metal ion from emusifiers and coagulants. 
     The emulsion polymerization used in this invention will be explained specifically. 
     The polymerization may be carried out in accordance with a conventional emulsion polymerization using a polymerization initiator such as a peroxide, a redox type compound, an azo type compound, a persulfate or the like. If necessary, a molecular weight regulator or other additives may be used. Any emulsion-polymerizable monomers can be used, and there is no restriction on the molecular weight of the resulting polymer. 
     The emulsion polymerization is conducted in a reactor freed of oxygen. Monomers, a nonionic surface active agent, an ionic surface active agent, a molecular weight regulator, a polymerization initiator, etc. may be added at one time before the start of reaction, or in any desired portions after the start of reaction. In the course of reaction, conditions such as temperature, stirring and the like may be changed as desired. 
     Any of continuous and batchwise polymerizations can be adopted. 
     The polymer latex thus obtained is subjected to monomer recovery by a conventional monomer recovery procedure such as by distillation under reduced pressure, steam distillation or the like, after which an electrolyte is added to the resulting polymer latex and the resulting mixture is then heated, upon which a polymer precipitates and can be isolated. The heating may be conducted batchwise in a vessel or continuously. 
     The polymer separated after the coagulation is optionally water-washed, and then dried to obtain a product polymer. 
     The polymer obtained according to the emulsion polymerization method of this invention, as compared with polymers obtained from ordinary emulsion polymerizations, has an extremely low content of metal ions such as alkali metals, alkaline earth metals and the like. 
     The thermosetting resin used in this invention is preferably an epoxy resin, a phenol resin, a urea resin, a melamine resin or the like. Of these, the epoxy resin and the phenol resin are more preferable. 
     The epoxy resin usable in this invention includes bisphenol type epoxy resins and special epoxy resins such as novolak type epoxy resins, polyphenol type epoxy resins, alicyclic type epoxy resins and rubber-modified epoxy resins. 
     The phenol resin used in this invention includes not only common resol type and novolak type phenol resins, but also cresol resins, xylenol resins and phenol resins modified by cresol, xylene, lignin, petroleum-based aromatic hydrocarbon resin, or the like. 
     In this invention, the ratio of the functional, rubbery copolymer to the thermosetting resin is 1 to 100  parts by weight, preferably 1 to 50 parts by weight, more preferably 2 to 30 parts by weight, of the former per 100 parts by weight of the latter. When the weight ratio is less than 1, no effect on impact resistance and molding shrinkage can be obtained. When the weight ratio exceeds 100, the volume resistivity which is characteristic of the thermosetting resins is impaired and the strength is reduced. 
     In curing the thermosetting resin composition of this invention, any of the curing agent used for conventional thermosetting resins can be employed. To the thermosetting resin composition of this invention can be further added, if necessary, filllers such as silica, clay, gipsum, calcium carbonate, quartz powder, kaolin, mica, sodium silicate, talc, calcium silicate, titanium compound, antimony compound and the like as well as additives such as a pigment, an antioxidant, a stabilizer, a plasticizer, a softener, a lubricant and the like. 
     The method of blending the thermosetting resin with the functional, rubbery copolymer is not critical, and a conventional roll, closed type mixer, extruder or the like may be used depending upon the rubber/resin ratio. 
     The thermosetting resin composition of this invention can effectively be used as not only a coating material for electronic parts but also an adhesive, an electrodeposition coating material, a lining material, a sealing material and other various molding materials. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     This invention will be explained specifically below by way of Examples; however, the invention is in no way restricted to these Examples. 
     EXAMPLES 1 TO 9 AND COMPARATIVE EXAMPLES 1 TO 5 
     Using the following polymerization recipe, emulsion polymerization was carried out at 20° C. in an autoclave having an internal volume of 20 liters: 
     
         ______________________________________Butadiene          55     parts by weightAcrylonitrile      35     parts by weightMethacrylic acid   10     parts by weightWater              220    parts by weightPolyoxyethylene nonyl-              5      parts by weightphenyl ether*.sup.1Tertiary dodecyl   0.2    parts by weightmercaptanAmmonium persulfate              0.25   parts by weightCyanoethylated     0.15   parts by weightdiethanolamine______________________________________ (*.sup.1 Emulgen 920 manufactured by Kao Corp. Cloud point: 82° C. 
    
     When the polymerization conversion reached 90%, 0.2 part by weight, per 100 parts by weight of the monomers, of hydroxylamine sulfate was added to terminate the polymerization. Subsequently, the reaction mixture was heated and subjected to steam distillation at about 70° C. under reduced pressure to recover the remaining monomers. To the resulting polymer latex was added 2 parts by weight of an alkylated phenol as an antioxidant. The resulting mixture was then placed in a pressure tube and heated to 110° C. to coagulate the latex. The resulting crumbs were taken out, waterwashed and thereafter dried at 50° C. under reduced pressure to obtain an evaluation sample of a rubbery copolymer (Sample 1). 
     Other samples shown in Table 1 were also obtained using similar recipes (Samples 2 to 12). 
     Blending of these samples with an epoxy resin was conducted in the following manner: 
     
         ______________________________________Epoxy resin*       100    parts by weightRubbery copolymer  20     parts by weightSilica powder      100    parts by weightDiethylene triamine              15     parts by weight______________________________________ (*Epikote 152 manufactured by Shell Chemical) 
    
     The epoxy resin and the rubbery copolymer were kneaded by means of a 4-inch electrically heated roll at 80° C. When the mixture became uniform, the silica powder was added and kneading was continued. Finally, diethyltetramine was added. 
     The epoxy resin composition obtained was powdered and subjected to press molding at 160° C. for 30 min to obtain a molded plate. 
     Test specimens for bending test and impact test in Table 2 were prepared by cutting the molded plate (4 mm in thickness) using a milling machine. 
     Metal-corrosiveness was measured in accordance with the following method: 
     An epoxy resin composition containing a given amount of a rubbery copolymer was cured and molded into a plate having a size of 10 mm×10 mm. 
     Separately, a copper plate of 2 mm in thickness (JIS H 3100) was cut to a size of 30 mm×30 mm. The thus obtained copper plate was thoroughly polished with a 100 mesh polishing paper and then degreased. 
     The polished copper plate was placed on the above epoxy resin composition plate of 10 mm×10 mm, and the resulting assembly was placed in a 300-ml sample bottle. The sample bottle was placed in a gear oven at 80° C. and allowed to stand for 24 hr. The copper plate was taken out and its degree of corrosion was checked visually. 
     Bending strength test, Izod impact test, volume resistivity, and shrinkage were measured in accordance with JIS K 6911. 
     The results of these tests are shown in Table 2. 
     EXAMPLE 10 
     The same procedure as in Example 1 was repeated with the same emulsion polymerization recipe as in Example 1, except that 1 part by weight of sodium dodecylbenzenesulfonate was added, to effect emulsion polymerization, and when the polymerization conversion reached 90%, the polymerization was terminated, after which the remaining monomers were removed and an antioxidant was added. 
     Subsequently, 10 parts by weight of ammonium sulfate was added in the form of a 20% by weight aqueous solution. The resulting mixture was heated to 90° C. to coagulate the latex. The crumbs formed were taken out, water-washed at 50° C. and dried under reduced pressure to obtain an evaluation sample (Sample 13). 
     The results of evaluation are shown in Table 2. 
     As seen from Table 2, the epoxy resin compositions according to this invention (Examples 1 to 10) have a high strength, a good impact resistance, a small molding shrinkage and no metal-corrosiveness. These effects are particularly remarkable when a rubbery copolymer having a carboxyl group is used. 
     Therefore, the epoxy resin compositions according to this invention are particularly effective as a molding, dipping, casting, embedding, encapsulating or sealing material for electronic parts. 
     EXAMPLE 11 
     Using the functional, rubbery copolymer obtained in Example 1 (Sample 1), a phenol resin composition was prepared with the following compounding recipe: 
     
         ______________________________________Resol type phenol resin               100 parts by weight(obtained by subjecting 1 partby weight of phenol and 1.8parts by weight of formaldehydeto condensation reaction at100° C. for 2 hr)Sample 1 (added in the form of                30 parts by weighta 50% by weight MEK solution)______________________________________ 
    
     The resin and the rubbery copolymer solution were kneaded at 60° C. for 5 min by means of a closed type kneader to obtain a resin composition. About 1 g of this composition was placed on a thoroughly polished copper plate of 30 mm×30 mm×2.0 mm (thickness). The resulting assembly was heated at 180° C. for 30 min in an oven to cure the composition. 
     Then, the assembly was allowed to stand for 24 hr in a constant temperature and constant humidity chamber controlled to 80° C. and 50% RH. Thereafter, the copper plate was taken out and its degree of corrosion was checked visually. No corrosion was found. 
     EXAMPLE 12 
     Using the functional, rubbery copolymer obtained in Example 10 (Sample 13), a phenol resin composition was prepared with the same compounding recipe as in Example 11. The composition was evaluated in the same manner as in Example 11. 
     No corrosion was found. 
     EXAMPLES 13 TO 26 AND COMPARATIVE EXAMPLES 6 TO 17 
     Samples 14, 15, 16 and 17 were prepared with the recipes shown in Table 3 in the same manner as in Example 1, and Samples 18 and 19 were prepared with the recipes shown in Table 3 in the same manner as in Example 10. 
     Sample 20 is for comparison and contains a polymer obtained by using a conventional anionic surface active agent and a metal salt as a coagulant. 
     Each sample was evaluated in accordance with the manner stated in Example 11. The results are shown in Table 4. 
     As is obvious from Table 4, the compositions of this invention, as compared with compositions comprising a polymer obtained by a conventional emulsion polymerization, are extremely low in metal-corrosiveness and, in the present compositions, curing of phenol resin can proceed satisfactorily. 
     Next, it will be shown below that the resin composition of this invention can be used as an excellent molding material. 
     100 parts by weight of a novolak resin, 10 parts by weight of Sample 1 and 10 parts by weight of hexamethylenetetramine (curing agent) were kneaded at 140° C. for 4 min on a roll. 
     The kneaded material was powdered and pressmolded to prepare a molded plate of 4 mm in thickness. 
     Using this plate, test specimens were cut by means of a milling machine. The specimens were subjected to bending strength test and Izod impact test in accordance with JIS K 6911. 
     The other rubbery copolymers shown in Table 3 were subjected to the same procedure as above. The test results are shown in Table 5. 
     Metal-corrosiveness in Table 5 was determined in accordance with the following method: A cured plate (4 mm in thickness) of a phenol resin composition containing a given amount of a rubbery copolymer was prepared, and cut into plates having a size of 10 mm×10 mm. Separately, a copper plate of 2 mm in thickness (JIS H 3100) was cut into plates having a size of 30 mm×30 mm and the thus obtained plate was thoroughly polished with a 100 mesh polishing paper and then degreased. 
     The polished copper plate was placed on the phenol resin composition plate of 10 mm×10 mm, and the resulting assembly was placed in a 300-ml sample bottle. The bottle was placed in a grear oven at 80° C. and allowed to stand for 24 hr. Then, the copper plate was taken out and its degree of corrosion was checked visually. 
     Comparative Example 17 did not use any rubbery copolymer. 
     As is obvious from Table 5, the phenol resin compositions according to this invention are materials having an excellent impact resistance and an excellent mechanical strength. 
     
                                           TABLE 1__________________________________________________________________________          Sample              Sample                  Sample                      Sample                          Sample                              Sample                                  Sample                                      Sample                                          Sample                                              Sample                                                  Sample                                                      Sample          1   2   3   4   5   6   7   8   9   10  11  12__________________________________________________________________________MonomerButadiene      55  55  55  55  65  62              30  25  35Acrylonitrile  35  35  35  35  35  35  3   3   3   25  20  25Butyl acrylate                         31  29  32  40  35  40Ethyl acrylate                         22  21  23Methoxyethyl acrylate                  41  37  42Methacrylic acid          10                  3       10      5Glycidyl methacrylate              10                  32-Hydroxypropyl methacrylate                  10                              20Diethylaminoethyl metha-   10crylateTertiarydodecyl mercaptan          0.71              0.65                  0.70                      0.70                          0.50                              0.60                                  0.10                                      0.10                                          0.03                                              0.20                                                  0.30                                                      0.22Amount of unit boundButadiene      57  57  57  56  64  60              32  27  36Acrylonitrile  34  35  35  35  36  37  3   3   3   25  21  25Butyl acrylate                         32  31  34  38  35  39Ethyl acrylate                         24  22  25Methoxyethyl acrylate                  39  35  38Methacrylic acid          9                   3       9       5Glycidyl methacrylate              8                   22-Hydroxypropyl methacrylate                  8Diethylaminoethyl metha-   9                           17crylateMooney viscosity ML.sub.1+4          61  70  52  60  73  56  42  58  49  56  71  50(100° C.)__________________________________________________________________________ 
    
     
                                           TABLE 2__________________________________________________________________________                                Example                                     Comparative                                            Comparative       Example 1             Example 2                   Example 3                          Example 4                                5    Example 1                                            Example                                                   Example__________________________________________________________________________                                                   6Rubbery copolymer       Sample 1             Sample 2                   Sample 3                          Sample 4                                Sample 6                                     Sample 5                                            JSR    Sample 7                                            N230S*.sup.1Bending strength       12.7  12.1  11.8   12.2  12.2 10.1   9.7    11.4(kgf/mm.sup.2)Izod impact strength       2.7   2.2   2.1    2.3   2.0  1.6    1.6    2.0(kgf · cm/cm)Volume resistivity       2.1 × 10.sup.15             1.8 × 10.sup.15                   1.5 × 10.sup.15                          1.5 × 10.sup.15                                1.1 ×                                     2.1 × 10.sup.14                                            1.0 × 10.sup.14                                                   1.6 ×                                                   10.sup.15(50% RH, 23° C.)              10.sup.15(Ω-cm)Shrinkage (mm/mm)       0.0051             0.0055                   0.0059 0.0053                                0.0053                                     0.0062 0.0063 0.0053Metal-corrosiveness       No    No    No     No    No   No     Corroded                                                   No       change             change                   change change                                change                                     change red color                                                   change__________________________________________________________________________                    Comparative       Comparative                                             Comparative              Example 7                    Example 3                          Example 8                                Example 9                                      Example 4                                             Example                                                    Example__________________________________________________________________________                                                    10   Rubbery copolymer              Sample                    Sample                          Sample                                Sample                                      Sample JSR    Sample              8     9     10    11    12     N640H*.sup.2                                                    13   Bending strength              11.9  8.6   11.8  12.2  9.0    8.9    12.7   (kgf/mm.sup.2)   Izod impact strength              2.6   1.6   2.1   2.3   1.5    1.5    2.7   (kgf · cm/cm)   Volume resistivity              2.0 × 10.sup.15                    2.2 × 10.sup.14                          9.6 × 10.sup.14                                1.9 × 10.sup.15                                      3.1 × 10.sup.14                                             2.6 × 10.sup.14                                                    2.0 ×                                                    10.sup.15   (50% RH, 23° C.)   (Ω-cm)   Shrinkage (mm/mm)              0.0049                    0.0065                          0.0052                                0.0051                                      0.0066 0.0064 0.0050   Metal-corrosiveness              No    No    No    No    No     Corroded                                                    No              change                    change                          change                                change                                      change red color                                                    change__________________________________________________________________________ *.sup.1 JSR N230S: Amount of bound acrylonitrile: 35% by weight, Mooney viscosity [ML.sub.1+4 (100° C.)]: 56 *.sup.2 JSR N640H: Butadieneacrylonitrile-acrylate terpolymer [Amount of bound acrylonitrile: 25% by weight, Mooney viscosity [ML.sub.1+4 (100° C.)]: 70]- 
    
     
                                           TABLE 3__________________________________________________________________________           Sample No.           1   13  18  14  15  16  17  19  20  10__________________________________________________________________________Polymerization recipe(parts by weight)Butadiene       55  55  55  55  --  --  25  30  55  66Acrylonitrile   35  35  35  35   3   3  20  35  35  34Butyl acrylate  --  --  --  --  31  29  35  40  --  --Ethyl acrylate  --  --  --  --  22  21  --  --  --  --Methoxyethyl acrylate           --  --  --  --  41  37  --  --  --  --Methacrylic acid           10  10  10  --  --  10  --   5  10  --Glycidyl methacrylate           --  --  --  --   3  --  --  --  --  --2-Hydroxypropyl methacrylate           --  --  --  10  --  --  --  --  --  --Diethylaminoethyl           --  --  --  --  --  --  20  --  --  --methacrylateTertiary dodecyl           0.71               0.71                   0.71                       0.70                           0.10                               0.10                                   0.20                                       0.20                                           0.71                                               0.90mercaptanEnaulgen 920     5   5   4   5   5   5   5   4  --   5Sodium dodecylbenzene-           --   1  --  --  --  --  --   2   5  --sulfonatePotassium oleate           --  --   2  --  --  --  --  --  --  --Ammonium sulfate           --  10  10  --  --  --  --  10  --  --Calcium chloride           --  --  --  --  --  --  --  --  10  10Coagulation temperature           110° C.               90° C.                   90° C.                       110° C.                           110° C.                               110° C.                                   110° C.                                       90° C.                                           60° C.                                               60° C.PolymerAmount of bound unitButadiene       57  57  57  56  --  --  27  32  57  64Acrylonitrile   34  34  35  35   3    3 21  25  34  36Butyl acrylate  --  --  --  --  32  31  35  38  --  --Ethyl acrylate  --  --  --  --  24  22  --  --  --  --Methoxyethyl acrylate           --  --  --  --  39  35  --  --  --  --Methacrylic acid            9   9   9  --  --   9  --   5   9  --Glycidyl methacrylate           --  --  --  --   2  --  --  --  --  --2-Hydroxypropyl --  --  --   9  --  --  --  --  --  --methacrylateDiethylaminoethyl           --  --  --  --  --  --  17  --  --  --methacrylateMooney viscosity           61  --  --  60  42  58  71  51  69  58__________________________________________________________________________ 
    
     
                                           TABLE 4__________________________________________________________________________       Example 11             Example 12                    Example 13                          Example 14                                 Example 15                                       Example 16                                              Example                                                    Example__________________________________________________________________________                                                    18Kind of rubbery       Sample 1             Sample 13                    Sample 18                          Sample 14                                 Sample 15                                       Sample 16                                              Sample                                                    Sample 19polymerAmount of rubbery       30    30     30    30     30    30     30    30polymer *.sup.1Metal-corrosiveness       No change             No change                    No change                          No change                                 No change                                       No change                                              No change                                                    No changeState after setting       Completely             Completely                    Completely                          Completely                                 Completely                                       Completely                                              Completely                                                    Completelyat 180° C. for 30 min       cured cured  cured cured  cured cured  cured cured__________________________________________________________________________       Comparative               Comparative                      Comparative   Comparative   Comparative       Example 6               Example 7                      Example 8                              Example 19                                    Example 9                                            Example                                                  Example__________________________________________________________________________                                                  10Kind of rubbery       Sample 20               JSR    JSR     Sample 1                                    Sample 20                                            Sample                                                  Sample 20polymer             N230S*.sup.2                      N640H*.sup.3Amount of rubbery       30      30     30      10    10      50    50polymer *.sup.1Metal-corrosiveness       Corroded to               Corroded to                      Corroded to                              No change                                    Changed to                                            No change                                                  Corroded to       reddish reddish                      reddish       brown color   reddish       brown color               brown color                      brown color                 brown colorState after setting       Insufficiently               Insuf- Insuf-  Completely                                    Insufficiently                                            Completely                                                  Insuf-at 180° C. for 30 min       cured (Tacky               ficiently                      ficiently                              cured cured (Slight-                                            cured ficiently       surface)               cured  cured         ly tacky)     cured__________________________________________________________________________ *.sup.1 Amount per 100 parts by weight of resol type resin *.sup.2 JSR 230S: Amount of bound acrylonitrile: 35% by weight, Mooney viscosity [ML.sub.1+4 (100° C.)]: 56 *.sup.3 JSR N640H: Butadieneacrylonitrile-acrylate terpolymer [Amount of bound acrylonitrile: 25% by weight, Mooney viscosity [ML.sub.1+4 (100° C.)]: 70]- 
    
     
                                           TABLE 5__________________________________________________________________________                                         Comparative     Example 21           Example 22                 Example 23                       Example 24                             Example 25                                   Example 26                                         Example 11__________________________________________________________________________Kind of rubbery     Sample           Sample                 Sample                       Sample                             Sample                                   Sample                                         Samplecopolymer 1     1     13    14    16    17    20Amount of 10    30    10    10    20    10    10rubbery polymer*.sup.1(parts by weight)Bending strength     4.1   5.2   3.9   3.5   3.6   3.1   4.0(kgf/mm.sup.2)Izod impact     2.5   4.8   2.5   2.0   2.7   2.4   2.5strength(kgf · cm/cm)Metal-corrosive-     No    No    No    No    No    No    Corrodedness      change           change                 change                       change                             change                                   change                                         to red                                         color__________________________________________________________________________      Comparative             Comparative                    Comparative                           Comparative                                  Comparative                                         Comparative      Example 12             Example 13                    Example 14                           Example 15                                  Example 16                                         Example 17__________________________________________________________________________Kind of rubbery      Sample Sample JSR    JSR    JSR    --copolymer  21     21     N230S  N640H  AR101*.sup.2Amount of  10     30     10     10     20     --rubbery polymer*.sup.1(parts by weight)Bending strength      2.6    3.9    2.9    2.6    2.4    2.2(kgf/mm.sup.2)Izod impact      1.8    3.0    2.1    1.4    1.1    0.9strength(kgf · cm/cm)Metal-corrosive-      No     No     Corroded to                           Corroded to                                  Corroded to                                         Noness       change change red color                           red color                                  red color                                         change__________________________________________________________________________ *.sup.1 Amount per 100 parts by weight of novolak resin *.sup.2 JSR AR101: Acrylic rubber having a Mooney viscosity [ML.sub.1+4 (100° C.)] of 50.