BLS 1328


BLS 1328 (25973-55-1) is a benzotriazole type ultraviolet light absorber (UVA), imparting good light stability for plastics and other organic polymers.  BLS 1328 protects polymers as well as organic pigments from UV radiation helping to preserve the original appearance and physical integrity of molded articles, films, sheets, and fibers during outdoor weathering.


Chemical Name:                     2-(2’-Hydroxy-3’, 5’-di-tert-amylphenyl) benzotriazole

CAS Number:                         25973-55-1

Chemical Structure:

BLS 1328

Typical Properties         

Product Form:                         Solid Melting Point:                 80-88oC

 Molecular Weight:                   351.5 g/mol


BLS 1328 is used in the light stabilization of a wide range of plastics, including polyolefins, polyurethanes, PVC, acrylics, styrenic polymers, unsaturated polyesters, and others. It is also useful in the light stabilization of adhesives and solvent-based coatings.


  • Strong absorption of ultraviolet radiation in the 300-400 nm region
  • Low color contribution
  • Good solubility in coating solvents
  • FDA cleared for use in adhesives

Guidelines for Use

Typical recommended use levels in plastics range between 0.1% and 0.5%, and in coatings between 1% and 3.0% based on total solids. Combinations with other light stabilizers such as HALS and benzoates often show enhanced performance in both plastics and coatings. The exact formulation to be used is dependent on the substrate, performance requirements, and other factors, and should be determined by the user based on testing to simulate actual conditions of use. Please contact Mayzo for specific recommendations.


This product may be stored up to two years in a sealed container. Containers should be kept tightly closed when not in use and stored in a cool, dry place.


Please consult the Safety Data Sheet (SDS) prior to handling or using this product.

FDA Regulations

BLS 1328 has been cleared for use in adhesives under 21 CFR §175.105. Please contact your Mayzo representative for complete details, including restrictions of use.

Downloadable Product Details:  Please view our BLS 1328 PDF

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