Multilayer film indicator for determining the integrity or authenticity of an item and process for using same

• US 5,095,210 A
• Filed: 04/06/1990
• Issued: 03/10/1992
• Est. Priority Date: 04/06/1990
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Wheatley, John A., Schrenk, Walter J.
• Primary Examiner(s): McGraw, Vincent P.
• Application Number:
  US07/506,036
• Time in Patent Office: 704 Days
• Field of Search: 356/71, 350/1.6, 250/339, 250/341
• US Class Current: 250/339.05
• CPC Class Codes: G01N 21/33 using ultraviolet light G01N21/39 takes precedence
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361
• CPC Class Codes: G06K 19/14 the marking being sensed by radiation

Abstract

A multilayer film indicator, mechanism and process for using the indicator for determining the integrity, authenticity, or conformance of an item to an original state, involving the measurement and comparison of the condition of the indicator to an identifiable original quality of the indicator. The identifiable original quality of the indicator is produced by the optical interactions of layers of diverse thermoplastic materials within a laminate of the indicator and is not readily visible to the naked eye.

Claims

1. A process for determining the integrity or authenticity of an item or its conformance to an original state, including the steps of:

associating a multilayer film indicator with said item, wherein the multilayer film indicator comprises a laminate of closely adjacent layers of two or more diverse thermoplastic materials of differing refractive indices which has an identifiable original quality arising from the optical interactions of the layers, such quality not being readily visible to the naked eye;

measuring the original quality;

measuring the laminate a second time; and

comparing the original and the second measurements to ascertain the presence or absence of the identifiable original quality.

2. A process as defined in claim 1, wherein the identifiable original quality is an identifiable original reflectance spectrum.

3. A process as defined in claim 1, wherein the second measurement follows a delivery of the item to the custody of another.

4. A multilayer film indicator associated with an item for indicating the integrity or authenticity of the item or its conformance to an original state, which in an initial condition is substantially colorless, and which when strained to a selected extent will produce and retain evidence of such strain which is not readily visible to the naked eye of an observer, including a laminate of closely adjacent layers of two or more diverse thermoplastic materials of differing refractive indices having an identifiable reflectance spectrum.

5. An indicator as defined in claim 4, wherein the evidence includes a shift in the identifiable reflectance spectrum of said indicator.

6. An indicator as defined in claim 5, wherein the yield point of at least one of the diverse thermoplastic materials has been at least equaled when the shift is produced.

7. An indicator as defined in claim 4, wherein the film indicator will rupture with a degree of additional strain while the evidence is still not readily visible to the naked eye of an observer.

8. A tamper evident, tamper resistant packaging material which includes an indicator as defined in claim 4.

9. An item which has been at least partially packaged within an indicator as defined in claim 4, such that the indicator has been joined to two portions of the item which are movable with respect to one another.

10. An item which has been embossed with an indicator as defined in claim 4.

11. A mechanism for determining the integrity or authenticity of an item or its conformance to an original state, including in cooperative combination:

a multilayer film indicator associated with the item and which includes a laminate of closely adjacent layers of two or more diverse thermoplastic materials of differing refractive indices having an identifiable original quality arising from the optical interactions of said layers which is not readily visible to the naked eye; and

means for comparing the condition of said laminate with the original quality.

12. A mechanism as defined in claim 11, wherein the identifiable original quality of the laminate of the multilayer film indicator is an identifiable original reflectance spectrum.

13. A mechanism as defined in claim 12, wherein said laminate consists essentially of at least one period of layers of a first thermoplastic material A having a refractive index n_A and an average layer thickness d_A and of a second thermoplastic material B having a refractive index n_B and an average layer thickness d_B in an ABAB-type layer order.

14. A mechanism as defined in claim 13, wherein λ

₀ =2(n_A d_A +n_B d_B) is less than about 0.4 micrometers or greater than about 0.7 micrometers.

15. A mechanism as defined in claim 14, wherein the laminate further includes outer skin layers which are transparent to visible light.

16. A mechanism as defined in claim 11, wherein:

the layers of the two or more diverse thermoplastic materials in the laminate of the indicator are arranged in one or more periods of P layers; and

##EQU3## is less than about 0.4 micrometers.

17. A mechanism as defined in claim 11, wherein the means for comparing the condition of the laminate with the original reflectance spectrum includes a printed copy of the reflectance spectrum.

18. A mechanism as defined in claim 17, wherein the means for comparing the condition of the laminate with the original reflectance spectrum further includes a spectrophotometer.

19. A mechanism as defined in claim 11, wherein the means for comparing the condition of the laminate with the original quality includes a written description or illustration of the original quality.

20. A mechanism as defined in claim 19, wherein said written description or illustration is intended to be previously or contemporaneously but separately communicated to one who is to employ the means for comparing the condition of the laminate with the original quality.

21. A mechanism as defined in claim 11, wherein the means for comparing the condition of the laminate with the original quality includes equipment for measuring the laminate with respect to the original quality.