Mixtures of Hindered Amine Light Stabilizers (HALS) and Zinc Oxide (ZnO) for UltraViolet Stabilization of Polyolefins, Especially Polyethylene Films
Publication Date: 2012-Apr-02
The IP.com Prior Art Database
The use of Hindered Amine Light Stabilizers (HALS) to protect polyolefins from degradation induced by sunlight is well known and widely used commercially. However, HALS are very expensive additives. The combined use of HALS and Zinc Oxide provides a cost effective stabilization package to protect polyethylene from UV radiation.
Polyolefins typically contain a primary antioxidant (such as a hindered phenol; a lactone or a hydroxylamine) and a secondary antioxidant (such as a hindered phosphite) as a stabilizer package when the finished polyolefin part is not intended for long term use. The full additive package might also include a processing additive (such as fluoroelastomer); an antistatic agent (such as glycerol monostearate or ethoxylated amine); an anti-block agent (such as silica or talc); a nucleating agent; and an acid neutralizer (such as a hydrotalcite or a fatty acid salt of Ca, Mg, or Zn – especially Ca stearate or Zn stearate).
If the finished part is intended for longer term use, additional additives are often included. Hindered Amine Light Stabilizers (HALS) are commonly used to protect plastic parts and plastic film against degradation that is induced by sunlight (UV radiation). Zinc oxide was commonly used before the commercial introduction of HALS. The use of a combination of a smaller amount of ZnO, together with HALS is also well known and is described in European patent application (“EPO”) 290,386 (Gugumus, to Ciba). The use of the same combination (i.e. ZnO + HALS) was also shown to be effective for the stabilization of polyethylene by Masina et al. in EPO 290,388 (to Ciba).
The use of ZnO plus at least two types of HALS has shown to be effective for the long term stabilization of polyolefins (especially polyethylene and polypropylene) in the following Great Britain (GB) patent applications:
GB 2,347,427 (Gugumus, to Ciba);
GB 2,332,677 (Gugumus, to Ciba);
GB 2,349,151 (Gugumus, to Ciba);
GB 2,354,245 (Gugumus, to Ciba); and
GB 2,316,410 (Gugumus, to Ciba);
The above GB applications make specific reference to the following types of commercially available HALS:
CHIMASSORB (sold by BASF, formerly Ciba)
TINUYN (sold by BASF, formerly Ciba)
CYTEC (sold by American Cyanamid)
The use of a combination of HALS and ZnO with other additives such a...