Thermally conductive resin composition

#The present invention relates to a resin composition having an excellent thermal conductivity and also to a thermally conductive cured product and an electronic part using the same.

#In recent years, electronic parts have been made into small sizes and arranged in a high density whereby their heat generation density per unit volume has been increasing. Therefore, there is a demand for enhancing a thermal conductivity of a thermally conductive adhesive which is used for adhering the constituting parts. As to a method for enhancing the thermal conductivity of the thermally conductive adhesive, there is exemplified a method wherein a filler having a high thermal conductivity is compounded. For example, in Patent Document 1, the adhesive is compounded with a high thermally conductive filler having a controlled particle size and shape whereby the thermal conductivity of the cured product is enhanced.

#However, when a monomer of an epoxy compound is compounded with a large amount of the thermally conductive filler for enhancing the thermal conductivity, viscosity of a resulting resin composition significantly increases, which results in deterioration of workability and decrease in adhesive force.

#<Epoxy Compound (A)>

#It is necessary that the epoxy compound (A) used in the present invention is in a liquid form at room temperature (25° C.). The compound is preferred to be in a liquid form even at 10° C. or lower, and more preferred to be in a liquid form even at 0° C. or lower. As a result that the epoxy compound (A) is in a liquid form, the thermal conductivity of the resin composition can be enhanced. The lower limit of the temperature at which the compound is in a liquid form is not particularly limited and, in an industrial view, −20° C. or higher is sufficient.

#There is no particular limitation for the epoxy compound (A) provided that it is in a liquid form at room temperature (25° C.). Examples thereof are bisphenol-type epoxy compounds prepared by glycidylating bisphenol such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol AD, tetramethylbisphenol S, terebromobisphenol A, tetrachlorobisphenol A and tetrafluorobisphenol A; epoxy compounds prepared by glycidylating divalent phenol such as biphenol, dihydroxynaphthelene and 9,9-bis(4-hydroxyphenyl)fluorene; epoxy compounds prepared by glycidylating trisphenol such as 1,1,1-tris(4-hydroxyphenyl)methane and 4,4-(1-(4-(1-(4-hydroxyphenyl)-1-methylethyl)phenyl)-ethylidene)bisphenol; epoxy compounds prepared by glycidylating tetrakisphenol such as 1,1,2,2-tetrakis(4-hydroxyphenyl)-ethane; novolak-type epoxy compounds prepared by glycidylating novolak such as phenol novolak, cresol novolak, bisphenol A novolak, brominated phenol novolak and brominated bisphenol A novolak; epoxy compounds prepared by glycidylating polyhydric phenol such as catechol, resorcinol, hydroquinone and benzenetriol; aliphatic ether-type epoxy compounds prepared by glycidylating polyhydric alcohol such as glycerol and polyethylene glycol; ether-ester-type epoxy compounds prepared by glycidylating hydroxy carboxylic acid such as p-oxybenzoic acid and β-oxynaphthoic acid; ester-type epoxy compounds prepared by glycidylating polycarboxylic acid such as phthalic acid and terephthalic acid; glycidylated compounds of an amine compound such as 4,4-diaminodiphenylmethane, m-xylylenediamine and aminophenol; glycidyl-type epoxy compounds of amine-type epoxy compound such as triglycidyl isocyanurate; and alicyclic epoxides such as 3,4-epoxy-cyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate. Each of them may be used solely or two or more of them may be used jointly. Among them, preferred ones are epoxy compounds prepared by glycidylating bisphenol A, epoxy compounds prepared by glycidylating bisphenol F, epoxy compounds of aminophenol type, epoxy compounds of m-xylylenediamine type or epoxy compounds of phenol novolak type, in view of excellent adhesive property and heat resistance property of the cured products.