Compounds of the general formula I ##STR1## in which R.sub.1 and R.sub.5 independently of one another denote hydrogen or lower alkyl, one of R.sub.2 and R.sub.3 denotes hydroxyl and the other denotes alkyl, cycloalkyl or aralkyl, R.sub.4 denotes hydrogen or, if R.sub.3 denotes hydroxyl, additionally also denotes alkyl, cycloalkyl or aralkyl, X denotes the direct bond, or a group ##STR2## wherein R.sub.8 is hydrogen, alkyl, aralkyl or phenyl and R.sub.9 is hydrogen, alkyl, aralkyl, phenyl or the group ##STR3## wherein R.sub.1 -R.sub.5 have the above meaning, of R.sub.9 conjointly with R.sub.8 is alkylene, Y denotes oxygen or sulfur, n denotes 1, 2, 3 or 4, R.sub.6 denotes tha acid radical of an n-valent organic oxygen acid or, if n is equal to 1, additionally also denotes hydroxyl or, if n is equal to 2, additionally also denotes --O--, and R.sub.7 denotes a lower alkyl group having 1 -3 carbon atoms, or, if n is equal to 1, additionally also denotes, conjointly with R.sub.6, a group Ia ##STR4## WHEREIN R.sub.1 -R.sub.5, X and Y have the above meaning, or if n is equal to 1 and Y denotes oxygen, additionally also denotes, conjointly with R.sub.6, a group Ib ##STR5## wherein R.sub.1 - R.sub.5 and X have the above meaning, and R.sub.10 is hydroxyl or the acid radical of a monovalent organic oxygen acid, for stabilising organic material.
Thermal stabilization of olefin polymers, particularly polypropylene. Stabilization is accomplished by means of an ester of a pentaerythritol monoacetal. The ester contains a phenolic group.
The present invention relates to a method for recrystallizing diacetal, such as 1,3:2,4-bis-O-(benzylidene)-D-sorbitol or a nuclearly substituted derivative thereof, in a polyolefin resin without giving a yellowish tint to the polyolefin resin; a polyolefin resin molded article containing a recrystallized diacetal which is obtainable by said recrystallization method; a method for producing polyolefin resin pellets containing the recrystallized diacetal by utilizing said recrystallization method, and polyolefin resin pellets obtainable by the above method; and a method for producing a polyolefin resin molded article by heating and melting said pellets at a temperature not lower than its sol-gel transition temperature during the heating cycle and rapidly cooling the melt; and a polyolefin resin molded article obtainable by said method.
Esters of monoacetals of pentaerythritol. The monoacetals result from the reaction of a 4-hydroxyphenylpropionaldehyde and pentaerythritol, and the further reaction of this monoacetal with either of two particular acid chlorides yields the esters of the invention. These esters are useful, in small proportions, to stabilize polymer compositions, especially olefin polymers.
Phenolic acetals wherein the phenolic groups are hindered by ortho substituents. The acetals are prepared by the reaction of certain phenolic aldehydes with alcohols or mercaptans and are effective to impart thermal stability to olefin polymers.
Thermal stabilization of olefin polymers, particularly polypropylene. Stabilization is accomplished by means of an ester of a pentaerythritol monoacetal. The ester contains a phenolic group.
