Textile applications of commercial photochromic dyes. Part 6: photochromic polypropylene fibres

Abstract

Two commercial photochromic dyes, a spirooxazine and a napthopyran, were successfully incorporated into polypropylene fibres by melt extrusion to produce fibres that showed intense photochromism. The technical performance of the photochromic dyes was investigated using a methodological approach that has been established and validated for the dyes applied by screen printing onto textiles in previous publications in this series. These parallel investigations allowed a comparison of the properties of the dyes in polypropylene and screen printed on cotton. The photocolorability of both dyes was found to be significantly higher in polypropylene compared with screen prints on cotton when applied at the same dye concentration. Of particular interest was the observation of positive solvatochromism, providing evidence that the photochromism is due to the colorants in solution in both media. The colour development rates during UV exposure of the dyes applied by screen printing cotton and by extrusion into polypropylene were similar. However, differences were observed in the thermal fading rates after removal of the UV source, in that the spirooxazine dye reverted more slowly in polypropylene, while the reverse was true in the case of the naphthopyran. Both dyes showed better photostability in polypropylene than in screen-printed textiles. A UV absorber and two hindered amine light stabilisers were found significantly to enhance the photostability of the dyes in polypropylene, although the presence of the UV absorber reduced the degree of photocoloration.

Facile development of photochromic cellulose acetate transparent nanocomposite film immobilized with lanthanide‐doped pigment: ultraviolet blocking, superhydrophobic, and antimicrobial activity

“…Moreover, the presence of hydroxyl and amino substituents in the composition of the UV stabilizer, such as hindered amine stabilizing agents, results in better hydrophilic characteristics. [ 72,73 ]…”

Investigating Photochromic Behavior of Organic Dyes in Solution Form using Multilevel Factorial Design

“…As spirooxazines are the photoreversible molecules that oscillate between two different states of closed and open form, the open form with its more polarized character can bind with metal ions especially trivalent metal ion Fe3 [6]. Spiropyran and naphthopyran photochromic dyes were incorporated into polypropylene fibres by melt extrusion for the production of fibres that showed better photostability in polypropylene than in screen-printed textiles [7].…”

Influence of Optical Brightening Agent Concentration on Properties of Cotton Fabric Coated with Photochromic Microcapsules Using a Pad-Dry-Cure Process

“…On glass plates, they are usually applied by sol-gel technology [19][20][21]. The incorporation of photochromic dye into the fiber is also established [22,23]. In general, photochromic…”