| 摘要 |
A substituted 1,3,3-trimethylindolinobenzopyrylospiran is mixed with a nonpigmented, organic-soluble, resin base paint or with an organic-soluble, resin base paint containing a small amount of white pigment and a thin coat of the mixture is applied to the surface of a laminated article. The coating is then activated by ultraviolet light. Activation causes the coating to assume a color. After activation, the coating is heated to a temperature of approximately 125 DEG F. Upon heating, any portion of the coating directly over a weakly bonded or nonbonded portion of the laminated article will return to its original colorless or white state. Any portion of the coating directly over a strongly bonded portion of the laminated article will retain its color. Thus, this invention is useful in that it permits the detection of weakly bonded or nonbonded portions of laminated articles.
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