Textile applications of photochromic dyes. Part 3: factors affecting the technical performance of textiles screen‐printed with commercial photochromic dyes

Abstract

The technical performance of five selected commercial photochromic dyes applied by screen-printing on textiles was evaluated using a colour measurement methodology that has previously been established and validated. The results of wash fastness assessments were distinctly unusual. With the selected spirooxazine dyes, the degree of photocoloration increased with initial washing and decreased with subsequent washings, while the naphthopyrans behaved more normally, showing a consistent marginal decrease in photocoloration with repeated washing. An explanation is proposed consistent with scanning electron microscopy examination of the binder film degradation and with the structural differences between the dye classes. The dyes in this application showed limited photostability. The incorporation of ultraviolet absorbers was found to increase photostability only to an extent specific to particular ultraviolet absorber ⁄ dye combinations. However, the presence of the ultraviolet absorber led to a consistent reduction in the degree of photocoloration of the dyes. In contrast, the incorporation of hindered amine light stabilisers significantly enhanced the photostability of the dyes, providing an increase in resistance to photodegradation of up to fivefold.

Textiles screen‐printed with photochromic ethyl cellulose–spirooxazine composite nanoparticles

“…However, interestingly it was most pronounced using the lower concentration of SO and Tinuvin 144 light stabilizer. It is in good agreement with the finding of Little et al [11], who also found that Tinuvin 144 enhanced not only the photochromic lifetime of spirooxazine significantly in a pigment printing method, but also the photocolouration on printed fabric.…”

“…These colour differences are hardly visible even under ideal visibility conditions [20]. These results clearly indicate that by doubling the SO concentration we could not reach substantial colour development similarly to the findings of a recent study of Little et al [11], in which authors showed that spirooxazine reaches a maximum colour development at a concentration of ca. 0.025 -0.05 % w/w in screen printing with disperse dye.…”

“…We found that 1.5 % w/w nanoparticles dispersion having 10 % w/w nanocapsules containing 30 % w/w SO provided intense blue colour, and 4 layers of printing supplied a homogeneous colour coating on cotton. Consequently, the SO concentration of the printing paste was 0.045 % w/w (1.26 x 10 -3 mol L -1 ) which is in the range that was used by Little et al [9][10][11] in their comprehensive studies. As a comparison we also investigated the application of photochromic nanocapsules containing a double amount The prepared photochromic pastes were printed on cotton fabrics using a flat bed screen printing machine, and then thermally polymerized.…”

“…Photochromic textiles have been prepared by conventional dyeing techniques that applied photochromic dyes in dispersed form in exhaust dyeing [4,7,8] and in screen-printing [9][10][11], or by attaching microcapsules containing photochromic dyes onto textile surfaces [12]. Nanomaterials such as particles, fibres, tubes or sheets coated on a substrate may display novel functionalities to the substrate because of the structure and size effect [13].…”

Inkjet printing and UV-LED curing of photochromic dyes for functional and smart textile applications

“…7 In recent literature, the development of UV-sensing textiles using photochromic dyes has been paid much attention. The integration of photochromic dyes into textile structures has been proven successful with traditional textile production techniques such as screen-printing, [8][9][10] dyeing 11,12 and mass dyeing. 10,13,14 Moreover, the application of photochromic dyes using novel production techniques has emerged.…”