Resealable packaging material

• US 5,089,320 A
• Filed: 11/09/1990
• Issued: 02/18/1992
• Est. Priority Date: 01/09/1989
• Status: Expired due to Term

• Current Assignee: Printpack Illinois, Inc. (Printpack Holdings Incorporated)
• Original Assignee: James River II, Inc.
• Inventors: Bower, William B., Straus, Steven J., Zuscik, Edward J., Yanidis, Apostol
• Primary Examiner(s): BUFFALOW, EDITH
• Application Number:
  US07/603,760
• Time in Patent Office: 466 Days
• Field of Search: 428/349, 428/517, 428/35.8, 428/483, 428/521
• US Class Current: 428/216
• CPC Class Codes: B32B 7/06 permitting easy separation
• CPC Class Codes: Y10T 428/1355 Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/2826 Synthetic resin or polymer
• CPC Class Codes: Y10T 428/31797 Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31917 Next to polyene polymer
• CPC Class Codes: Y10T 428/31931 Polyene monomer-containing

Abstract

A machinable flexible packaging material capable of forming a seal that is reclosable at ambient temperature is made by applying a tacky adhesive and a thin skin layer onto a substrate, such as polyester film. Being thin, the skin layer fractures when the seal is opened, thereby allowing the adhesive to form a resealable interface at the seal area. However, since the adhesive is encapsulated in the material initially, the material may be used like other packaging materials in form, fill and seal machines.

Claims

1. A flexible packaging material comprising a substrate layer, a layer of tacky adhesive adjacent the substrate layer, and a skin layer covering the layer of tacky adhesive, the skin layer having a thickness between about 0.05 and 0.5 mil, each surface of the packaging material having a coefficient of friction such that the material is machinable in a packaging machine, the material being capable of being sealed to itself by the sealing jaws of the packaging machine to form a package having a seal which has an initial bond strength such that the package remains closed during normal handling but which can be readily pulled apart manually to open the package, the skin layer being fractured when the seal is pulled apart such that the tacky adhesive is exposed at the surface of the seal area, whereby the packaging material may be resealed to itself at the area of the seal by the application of manual pressure alone to reclose the package.

2. The packaging material of claim 1 wherein the coefficient of friction to stainless steel is between about 0.1 and 0.5.

3. The packaging material of claim 1 wherein the tacky adhesive contains a fragrance.

4. The packaging material of claim 1 wherein the tacky adhesive is a pressure sensitive adhesive.

5. The packaging material of claim 4 wherein the skin layer and the layer of pressure sensitive adhesive are coextruded together either with the substrate layer or onto the substrate layer, and the skin layer is fractured by rupturing through to the adhesive layer and then delaminating from the substrate layer when the seal is pulled apart, thereby exposing the pressure sensitive adhesive at the seal area.

6. The packaging material of claim 5 wherein the pressure sensitive adhesive comprises from about 40 to 80 percent of a thermoplastic elastomer and from about 20 to 60 percent of a tackifier.

7. The packaging material of claim 5 wherein the skin layer is a layer of a thermoplastic film-forming polymer capable of forming a heat seal when the jaws have a temperature of 230°

F. (110°

C.).

8. The packaging material of claim 7 wherein the skin layer comprises an ionomer.

9. The packaging material of claim 7 wherein the heat seal has an initial bond strength between about two and five pounds per square inch (0.4 and 0.9 kg/cm).

10. The packaging material of claim 9 wherein the strength of the resealable bond formed by the pressure sensitive adhesive is between about 0.5 and 4 pounds per inch (0.1 and 0.7 kg/cm).

11. The packaging material of claim 1 wherein the thickness of the layer of pressure sensitive adhesive is between about 0.1 and 2.0 mil (2.5 and 51 microns).

12. The packaging material of claim 1 wherein the skin layer is fractured by the sealing jaws such that the jaws disrupt the skin layer such that the tacky adhesive becomes present at the interface where the material is sealed to itself.

13. The packaging material of claim 12 wherein the temperature of the sealing jaws is less than the melting point of the substance forming the skin layer.

14. The packaging material of claim 12 wherein the seal has an initial bond strength between about two and five pounds per inch (0.4 and 0.9 kg/cm).

15. The packaging material of claim 14 wherein the strength of the resealable bond formed by the tacky adhesive is between about 0.5 and 4 pounds per inch (0.1 and 0.7 kg/cm).

16. The packaging material of claim 12 wherein the skin layer consists of finely divided particulate matter.

17. The packaging material of claim 16 wherein the particulate matter is talc or starch particles.

18. A method of forming the packaging material of claim 12 comprising transferring the layer of adhesive to the substrate from a carrying medium.

19. The method of claim 17 wherein the skin layer is transferred to the substrate with the adhesive and the carrying medium is paper coated with a silicone release agent.