Transparent overlay for protecting a document from tampering

• US 5,060,981 A
• Filed: 09/19/1989
• Issued: 10/29/1991
• Est. Priority Date: 09/19/1989
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Fossum, Douglas K., McConville, John W., Jongewaard, Susan K.
• Primary Examiner(s): Bell, Paul A.
• Application Number:
  US07/409,144
• Time in Patent Office: 770 Days
• Field of Search: 283/109, 283/74, 283/75, 283/77, 283/85, 283/86, 283/87, 283/91, 283/90, 283/904
• US Class Current: 283/109
• CPC Class Codes: B41M 5/5254 characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers
• CPC Class Codes: B41M 7/0027 using protective coatings or layers by lamination or by fusion of the coatings or layers
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: Y10S 283/904 Credit card
• CPC Class Codes: Y10T 428/264 Up to 3 mils

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 a polymeric image-receiving layer over 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. When the polymeric image-receiving layer is dye-receptive, it can be imaged by using a thermal printing head with a dye-donor element. A preferred polymeric image-receiving layer that is dye-receptive is chlorinated poly(vinylchloride).

Claims

1. A document having a transparent overlay comprising:

(a) a transparent cover sheet,

(b) a layer of hot-melt adhesive over one surface of said transparent covering, which adhesive has a Tg of at least about -15°

C., and

(c) a polymeric image-receiving layer over the exposed face of said hot-melt adhesive layer, which image-receiving layer is no more than about 50 μ

m in thickness,

said overlay being bonded to the document by said hot-melt adhesive.

2. A document as defined in claim 1 wherein said polymeric image-receiving layer bears an image which is protected from tampering by the transparent overlay.

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

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

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

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

6. A transparent overlay by which a document can be protected from tampering, 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 Tg of at least about -15°

C., and

(c) a polymeric image-receiving layer over the exposed face of said hot-melt adhesive layer, which image-receiving layer is no more than about 50 μ

m in thickness.

7. A transparent overlay as defined in claim 6 wherein said transparent cover sheet is a thermoplastic film.

8. A transparent overlay as defined in claim 6 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.

9. A transparent overlay as defined in claim 6 wherein the major polymeric component of said polymeric image-receiving layer is selected from poly(vinylchloride)s, polyesters, cellulosic derivatives, polyvinylpyrollidones, polycarbonates, butyral vinyl acetates, acrylates, methacrylates, and styrene/acrylonitrile copolymers.

10. A transparent overlay as defined in claim 9 wherein the Tg of said major polymeric component is from about 60°

to about 150°

C.

11. A transparent overlay as defined in claim 6 wherein said polymeric image-receiving layer comprises chlorinated poly(vinylchloride) having a Tg no lower than about 80°

C., and an inherent viscosity of about 0.4-1.5.

12. A transparent overlay as defined in claim 6 wherein said hot-melt adhesive has a Tg of from about 40°

C. to about 100°

C.

13. A transparent overlay as defined in claim 12 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.

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

m.

15. A transparent overlay as defined in claim 6 wherein the thickness of the polymeric image-receiving layer is from about 8 to about 25 mm.