Colorimetric indicator of radiation exposure
View Patent ↗A colorimetric composition is disclosed comprising a polycarbonate resin, a dye, and a thiopropionate. The composition undergoes an irreversible color shift to a darker color upon exposure to sunlight or UV radiation. Processes for producing and/or using such a colorimetric composition are also disclosed.
1. A colorimetric composition comprising:
a polymeric resin;
a dye selected from the group consisting of azo dyes and carbonyl-containing dyes; and
a thiopropionate;
wherein when the dye is an azo dye, the azo dye is selected from C.I. Solvent Red 23; C.I. Solvent Red 24; C.I. Solvent Yellow 56; C.I. Solvent Yellow 14; or C.I. Solvent Yellow 16,
wherein when the dye is a carbonyl-containing dye, the carbonyl-containing dye is selected from C.I. Solvent Orange 60, C.I. Solvent Red 135, C.I. Solvent Red 179, or C.I. Solvent Yellow 104; wherein the colorimetric composition is a blend of the polymeric resin, dye, and the thiopropionate; and
wherein the polymeric resin is transparent and wherein a 0.125 inch thick plaque of the composition is capable of shifting from transparent to a dark color as measured using CIELab, wherein the dL* of the dark color is from −1.0 to −20.0 after 1,000 hours exposure according to ASTMG26.
2. The composition of claim 1 , wherein the carbonyl-containing dye is selected from the group consisting of perylene dyes and perinone dyes.
3. The composition of claim 2 , wherein the dye is a solvent dye.
4. The composition of claim 1 , wherein the dye contains no sulfonic acid or carboxylic acid groups.
5. The composition of claim 1 , wherein the dye is present in the amount of from about 0.0001% by weight to about 10% by weight of the composition.
6. The composition of claim 1 , wherein the thiopropionate is pentaerythritol tetrakis (betalaurylthiopropionate).
7. The composition of claim 1 , wherein the thiopropionate is present in the amount of from 0.05% by weight to about 10% by weight of the composition.
8. The composition of claim 1 , wherein the thiopropionate is present in the amount of from 0.05% by weight to about 0.4% by weight of the composition.
9. The composition of claim 1 , wherein the composition has a haze level of 5% or less at a thickness of 3.2 millimeters, as measured by ASTM D1003.
10. A composition, comprising:
a polycarbonate resin;
a perinone dye; and
a thiopropionate;
wherein the perinone dye is selected from C.I. Solvent Orange 60, C.I. Solvent Red 135, and C.I. Solvent Red 179, or C.I. Solvent Yellow 104, wherein the composition is a blend of the polycarbonate resin, the perinone dye, and the thiopropionate, wherein the polymeric resin is transparent.
11. The composition of claim 10 , wherein the perinone dye is present in the amount of from about 0.0001% by weight to about 10% by weight of the composition.
12. The composition of claim 10 , wherein the thiopropionate is pentaerythritol tetrakis(betalaurylthiopropionate).
13. The composition of claim 10 , wherein the thiopropionate is present in the amount of from 0.05% by weight to about 10% by weight of the composition.
14. A method for monitoring the exposure of an article to ultraviolet radiation, comprising:
providing a composition comprising a polycarbonate resin, a dye selected from the group consisting of azo dyes and carbonyl-containing dyes, and a thiopropionate; wherein the composition is a blend of the polycarbonate resin, the dye, and the thiopropionate, and wherein the polymeric resin is transparent;
associating the composition with an article to be monitored; and
detecting a shift in the color of the composition from transparency to a darker color as measured by CIELab, wherein a 0.125 inch thick plaque of the composition is capable of shifting to a dark color, wherein the dL* of the dark color is from −1.0 to −20.0 after 1,000 hours exposure according to ASTMG26, the degree of shift indicating the amount of ultraviolet radiation to which the article has been exposed.
15. The method of claim 14 , wherein the dye is a perinone dye.
16. The method of claim 14 , wherein the associating step is performed by affixing the composition to the article to be monitored.
17. An article comprising the composition of claim 1 .
18. The article of claim 17 , wherein the composition of claim 1 is affixed to the article.
19. The article of claim 17 , wherein the composition of claim 1 is attached to the article.
20. The article of claim 17 , wherein the composition is molded.