Development of structured natural dyes for use into plastics

作者：Velho Sergio R K^*; Brum Luis F W; Petter Carlos O; dos Santos Joao Henrique Z; Simunic Stefanija; Kappa Wilfried Helmut

来源：Dyes and Pigments, 2017, 136: 248-254.

DOI：10.1016/j.dyepig.2016.08.021

• Natural dyes
• Sol-gel process
• Xenon-accelerated
• Weathering

This study aimed to identify whether natural dyes encapsulated in a silica matrix via the sol-gel process with the use of alkoxides (as described in INPI patent BR 10 2013 0219835) and subsequently injected into a polyvinyl chloride (PVC) matrix would preserve their original color characteristics after being subjected to Xenon-accelerated weathering (using the ASTM D4452-12 standard). A comparison was conducted of the same natural dyes - carmine, turmeric, indigo and annatto - with and without encapsulation, injected into the same PVC matrix. Color change measurements were made before the weathering test and after 126 h, 252 h, 378 h and 504 h in a Xenon weathering chamber using the ASTM D4459-12 standard. A non-encapsulated Tartrazine dye (INS 102, an azo dye) was used for comparison of the behavior of natural dyes vs. that of synthetic ones. The results pointed to a lack of discoloring protection for the encapsulated natural dyes, which lost saturation more severely than the non-encapsulated ones. It thus follows that some care-is required during the encapsulation stages of natural dyes, such as careful dispersion of natural colorants and the inclusion of repeat stages for the encapsulation of the xerogel.

• 出版日期2017-1