Acrylics are differentiated from other types of plastics by an unique combination of economy, high transparency and impressive optical properties. As an added benefit, they are more inherently light stable than other polymers
Stabilization
Ciba® IRGANOX® B 900, Ciba® IRGASTAB® FS 301, or combinations of Ciba® IRGANOX® B 245 with Ciba® IRGAFOS® 168 provide excellent processing and extended long-term thermal stability to PMMA.
For the protection of PMMA against light, usually a combination of UV absorbers and HALS provides the best performance. Depending on the application, different product combinations are recommended. For extrusion molded thick applications, either a combination of Ciba® TINUVIN® 571 and Ciba® TINUVIN® 765 or a combination of Ciba® TINUVIN® P and Ciba® TINUVIN® 770 is recommended. For thin applications such as films, combinations of Ciba® CHIMASSORB® 119 and Ciba® TINUVIN® 360 provide excellent light stability.
For cast sheets, Ciba® TINUVIN® 123 or Ciba® TINUVIN® 770 in combination with a UV absorber such as Ciba® TINUVIN® 571 is highly recommended. For special effects, fluorescent whitening agents such as Ciba® TINOPAL® OB is used.
Coloration
Colorants most suitable for this group of polymers are polymer soluble colorants or dyes, offered in our Ciba® ORACET® range. Due to their solubility, they allow the polymer to retain its transparency. PMMA has a high glass transition temperature and good solvating power, and as such, there is little risk of migration when polymer soluble colorants are used. With this solubility existing at the molecular level, these colorants develop high color strength even at low concentrations. Therefore good heat resistance and fastness properties like light fastness are required.
Opaque shades can be produced economically by combining polymer soluble colorants with Titanium Dioxide or inorganic pigments. Organic pigments from our Ciba® CROMOPHTAL® range exist showing heat resistance suitable for extrusion grades of PMMA. However, the selection process becomes much more difficult for injection molding, which in general requires higher heat resistance. Certain pigments exhibit partial solubility at low concentrations resulting in uncontrollable shade changes during processing.
For further information, please contact us.
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