Method for imparting improved discoloration resistance to articles
US5190710A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 22, 1991 |
| Grant date | Mar 2, 1993 |
| Priority date | — |
| Expiry date | Feb 22, 2011 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08K5/3435
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Excellent color stabilization as well as integrity is obtained in thin film and fibers exposed to bright sunlight at relatively high temperature, in polyolefin (PO) articles pigmented with blue and green phthalocyanine, and red azo and disazo pigments. The pigment is combined with two `large molecule` primary stabilizers, the first a piperidyl-based (PDYL) hindered amine light stabilizer (HALS), and the second, a 3,5-disubstituted-tert-butyl-4-hydroxybenzoate (3,5-DHBZ). The first contains at least two polysubstituted piperidyl rings in its molecule; the second is a hindered phenol with an ester group in the para- position. Stabilization of the PO's color is obtained for as long as the PO articles themselves are stabilized by the combination of primary stabilizers, typically, their useful life. With the combination, the pigmented articles are not only thermooxidatively and light-stabilized, but there is exceptionally low color fade. Because fibers may be extruded twice for better distribution of pigment, a small amount, no more than 0.1 phr of secondary melt-stabilizers, may be used. Blue-green- and red-pigmented PO articles exhibit less than a .+-.3 change in color (color fading) …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.