Abstract: The present invention relates to a stabilizer composition for organic polymer material containing (a) 6-hydroxychroman compound, a phosphorus antioxidant and (c) phenolic antioxidant, wherein the component (a) is contained in a proportion of 0.5 wt %-10 wt % and the total amount of the component (b) and the component (c) is in a proportion of 99.5 wt %-90 wt %, of the total amount of the components (a), (b) and (c). The present invention also relates to an organic polymer material composition containing an organic polymer and the above-mentioned stabilizer composition for organic polymer material. The use of the stabilizer composition of the present invention as a stabilizer for organic polymer materials affords an industrially extremely useful stabilized organic polymer material composition superior in heat stability during processing.

Abstract: Biphenyl and phosphorus trichloride are reacted in the presence of aluminum chloride, a hydrogen chloride gas generated is removed, a pyridine is added, excess phosphorus trichloride is removed, a resulting reaction product containing the obtained phosphine compound of the formula: and a phenol compound of the formula: wherein R is a hydrogen atom or methyl and R1 and R2 are each a hydrogen atom or alkyl having 1 to 5 carbon atoms, are reacted in the presence of a base as a deacidifying agent, and hydrochloride of this base and a pyridine-aluminum chloride complex are removed. By this method, a high quality phosphonite compound containing phosphinobiphenylene of the formula: can be produced safely in a high yield.

Abstract: A phenol compound of the formula ?1! ##STR1## wherein each of X's is a group of the formula ?2! ##STR2## wherein R.sub.1 and R.sub.4 are the same or different and each is an alkyl having 1 to 8 carbon atoms, and R.sub.2, R.sub.3, R.sub.5 and R.sub.6 are the same or different and each is a hydrogen atom or an alkyl having 1 to 8 carbon atoms; a stabilizer for organic materials which comprises the compound; a composition comprising the compound and an organic material; and a composition comprising the composition and a sulfur antioxidant, and use thereof.The compound of the present invention as used as a stabilizer for an organic material shows superior preventive effect against oxidative degradation and extremely superior resistance against degradation of an organic material in an environment involving contact with hot water for a long time, as compared to compounds conventionally used as hot water resistant antioxidants.