Claims
- 1. A method of marking an article to provide protection against forgery comprising the step of applying to the article to be marked a film comprising a laminate comprised of two transparent films joined to one another over their surface, each of said films being oriented by stretching and being comprised of a polyester resin and in admixture therewith an organic dyestuff which is heat stable at temperatures above about 260.degree. C., wherein one of the laminated transparent film layers comprises as the dyestuff anthraceno [2, 1-m; 1,9 a-n; 9a, 9-a] thioxanthene and the other film layer comprises as the dyestuff N-(n-octadecyl)-benzo [k,1] thioxanthene-3,4-dicarboximide.
- 2. A method according to claim 1 wherein said film has a transparency of at least 50 percent when exposed to light having a wave length of 750 nm.
- 3. A method according to claim 1 or 2 wherein said film is applied to the article to be marked by wrapping the article in the film.
- 4. A method according to claim 1 or 2 wherein said film is attached to the article to be marked by securing a strip of said film to the article.
- 5. A method of protecting an article against forgery, comprising the steps of:
- applying a laminate to the outside of the article, said laminate comprising two transparent polyester films, each film layer comprising a different organic dyestuff which is heat stable at temperatures above about 260.degree. C. and each of said dyestuffs having a different chemical structure and exhibiting a different characteristic color;
- directing a light beam onto said laminate; and
- detecting the color pattern of said dyestuffs, whereby said laminate exhibits one characteristic color when viewed by transmitted light and each of said film layers exhibits a different characteristic color when viewed by reflected light.
- 6. A method as defined by claim 5, wherein said color pattern is detected by the naked eye.
Priority Claims (1)
Number |
Date |
Country |
Kind |
7832840[U] |
Nov 1978 |
DEX |
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Parent Case Info
This is a division of application Ser. No. 084,551, filed Oct. 15, 1979, now U.S. Pat. No. 4,341,833.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4041206 |
Tsunashima et al. |
Aug 1977 |
|
4198458 |
Mitsuishi et al. |
Apr 1980 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
7025989 |
Jul 1970 |
DEX |
Divisions (1)
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Number |
Date |
Country |
Parent |
084551 |
Oct 1979 |
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