Transparent tamper-indicating document overlay

• US 4,968,063 A
• Filed: 09/19/1989
• Issued: 11/06/1990
• Est. Priority Date: 09/19/1989
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: McConville, John W., Fossum, Douglas K., Jongewaard, Susan K.
• Primary Examiner(s): Watts, Douglas D.
• Assistant Examiner(s): Hamill, Jr., Thomas
• Application Number:
  US07/409,098
• Time in Patent Office: 413 Days
• Field of Search: 380/105, 380/109, 380/106, 380/107, 283/67, 283/81, 283/101, 283/107, 283/108, 283/109, 283/106, 283/105, 283/72, 283/74, 283/90, 283/91, 283/98, 283/901, 156/292, 156/277, 40/135
• US Class Current: 283/72
• CPC Class Codes: B42D 2033/04 Transparent material
• CPC Class Codes: B42D 2033/06 Translucent material
• CPC Class Codes: B42D 2033/18 Reflecting material
• CPC Class Codes: B42D 2033/30 Plastic material
• CPC Class Codes: B42D 2035/34 Markings visible under particular conditions or containing coded information
• CPC Class Codes: B42D 25/00 Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof printing processes to produce identification or security features B41M3/14
• CPC Class Codes: B42D 25/36 comprising special materials
• CPC Class Codes: B42D 25/455 using heat
• CPC Class Codes: B42D 25/47 using adhesives

Abstract

A transparent overlay that can protect a document from tampering has a transparent cover sheet, a layer of hot-melt adhesive over one surface of the transparent cover sheet, and an image formed on the exposed face of said hot-melt adhesive layer. The transparent cover sheet can be a simple thermoplastic film but preferably is retroreflective sheeting which can bear a pattern or legend that is noticeable only when viewed retroreflectively.

Claims

1. A transparent overlay by which a document can be protected from tapering said overlay comprising:

(a) a transparent flexible cover sheet;

(b) a layer of hot-melt adhesive over one surface of said transparent cover sheet, which adhesive has a glass transition temperature of at least about -15°

C.; and

(c) an image formed on the exposed face of said hot-melt adhesive layer, which image is visible through said transparent cover sheet.

2. A transparent overlay as defined in claim 1 wherein said transparent cover sheet is a thermoplastic film.

3. A transparent overlay as defined in claim 1 wherein said transparent cover sheet is retroreflective sheeting which incorporates means for bearing a pattern or legend that is readily legible only when viewed retroreflectively.

4. A transparent overlay as defined in claim 1 wherein said hot-melt adhesive has a a glass transition temperature of from about 40°

C. to about 100°

C.

5. A transparent overlay as defined in claim 4 wherein said hot-melt adhesive comprises a linear, random copolyester of one or more aromatic dibasic acids and one or more aliphatic diols, modified with up to about 30 mole % of one or more aliphatic dibasic acids.

6. A transparent overlay as defined in claim 1 wherein the thickness of said hot-melt adhesive is from about 25 to about 200 μ

m.

7. A transparent overlay as defined in claim 1 and further comprising a barrier layer between the hot-melt adhesive layer and the cover sheet.

8. A document having a transparent overlay comprising:

(a) a transparent flexible cover sheet;

(b) a layer of hot-melt adhesive over one surface of said transparent cover sheet, which adhesive has a glass transition temperature of at least about -15°

C.; and

(c) an image formed on the exposed face of said hot-melt adhesive layer, which image is visible through said transparent cover sheet;

said overlay being laminate to said document by said hot-melt adhesive.

9. A document as defined in claim 8 wherein said transparent cover sheet comprises retroreflective sheeting.

10. A document as defined in claim 8 wherein said retroreflective sheeting bears a pattern or legend that is readily legible only when the document is viewed retroreflectively.

11. A document as defined in claim 8 wherein said transparent cover sheet is a thermoplastic film.