Abstract: To provide phosphorus-containing epoxy resins and phosphorus-containing epoxy resin compositions having high levels of appearance, yield and economic efficiency and cured products thereof that are used for various applications. A phosphorus-containing phenol compound represented by Formula (3) obtained by reacting a compound represented by Formula (2) with a compound represented by Formula (1), wherein in the peak area (A) of the component represented by Formula (1) on a chromatogram measured under specific conditions by gel permeation chromatography, peak area (B) on the high-molecular-weight side of the component of Formula (1), and total area (C) of peak area (A) and peak area (B), the value obtained by dividing peak area (B) by total area (C) is 8 area % or less, and epoxy resin compositions and cured products comprising the phosphorus-containing phenol compound as an essential ingredient.

Abstract: To provide phosphorus-containing epoxy resins and phosphorus-containing epoxy resin compositions having high levels of appearance, yield and economic efficiency and cured products thereof that are used for various applications. A phosphorus-containing phenol compound represented by Formula (3) obtained by reacting a compound represented by Formula (2) with a compound represented by Formula (1), wherein in the peak area (A) of the component represented by Formula (1) on a chromatogram measured under specific conditions by gel permeation chromatography, peak area (B) on the high-molecular-weight side of the component of Formula (1), and total area (C) of peak area (A) and peak area (B), the value obtained by dividing peak area (B) by total area (C) is 8 area % or less, and epoxy resin compositions and cured products comprising the phosphorus-containing phenol compound as an essential ingredient.

Abstract: This invention relates to a semiconductor encapsulating novolac type epoxy resin with the reduced stress, which is obtained by an addition reaction 1 to 15% of a novolac type epoxy resin of the following formula with a monohydric or dihydric aliphatic alcohol: ##STR1## (wherein R.sub.1 is hydrogen, halogen, alkyl, or aryl; R.sub.2 is selected from the group consisting of hydrogen, alkyl, aryl, or aryl having a substituent which may be glycidylether; and n is an integer not less than 0.