Abstract: Tris[2-hydroxy-3-(2,2,6,6-tetramethyl-4-piperidylamino)propyl] isocyanurate is useful as a light stabilizer for organic materials. A composition comprising an organic material and the isocyanurate is stable against light and also excellent in heat resistance. The isocyanurate can be produced by the reaction between tris(2,3-epoxypropyl) isocyanurate and 4-amino-2,2,6,6-tetramethylpiperidine.

Abstract: Halogen-containing resins, particularly polyvinyl chloride, are stabilized by the incorporation of a phosphite of the formula, ##EQU1## wherein one or two of groups R.sub.1, R.sub.2 or R.sub.3 has the formula, R(OC.sub.n H.sub.2n).sub.m --, in which R is an alkyl unsubstituted or substituted with at least one hydroxyl or chlorine, an alkenyl unsubstituted or substituted with at least one hydroxyl or chlorine, or an aralkyl, n has a value of from 1 to 4, and m has a value of from 1 to 8, and the remaining group R.sub.1, R.sub.2 and/or R.sub.3 is an alkyl unsubstituted or substituted with at least one hydroxyl or chlorine, an alkenyl unsubstituted or substituted with at least one hydroxyl or chlorine, an aralkyl or an unsubstituted aryl.