Importance

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Abstract

Excellent color stabilization as well as fiber integrity is obtained in bright sunlight and at relatively high temperature, in polyolefin (PO) articles pigmented with phthalocyanine pigments, by combining the pigment with two `large molecule` primary stabilizers, the first a hindered amine light stabilizer (HALS) and the second a metal-organic phosphonate. The first contains at least one triazine ring, and each substitutable position on each triazine ring is substituted with an oxo-piperazinyl group; the second is a 2.1 complex of an alkylated phenol phosphonate with a Group VIII or Group IIA metal, e.g. a metal bis[O-alky(3,5-di-t-butyl-4-hytdroxybenzyl)] phosphonate ('35-DHBP'). Stabilization of the PO's color is obtained for as long as the PO articles themselves are stabilized by the combination of primary stabilizers. With the combination, phthalocyanine pigmented articles are not only thermooxidatively and light-stabilized, but there is exceptionally low color fade. Because fibers are extruded twice for better distribution of pigment, a small amount, no more than 0.1 phr of a secondary melt-stabilizer, may be used. Blue- and green-pigmented PO articles in particular, so stabilized, exhibit less than a .+-.2 change in color (color fading) due to degradation of the pigment, over exposure resulting in absorption of 1240 Kjoules. Such exposure, deemed equivalent to exposure to sunlight for about 2 years in Florida at a 45.degree. South exposure, of PP fibers pigmented with the combination of primary stabilizers suffer essentially no loss of color due to degradation of the pigmented polymer.

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