Temperature switchable adhesives comprising crystallizable abietic acid derivative-based tackifiers

• US 7,399,800 B2
• Filed: 04/15/2005
• Issued: 07/15/2008
• Est. Priority Date: 04/15/2005
• Status: Expired due to Fees

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Burch, Robert Ray
• Primary Examiner(s): SZEKELY, PETER A
• Application Number:
  US11/108,007
• Publication Number:
  US 20060235121A1
• Time in Patent Office: 1,187 Days
• Field of Search: 524270-274
• US Class Current: 524/274
• CPC Class Codes: C08K 5/101 of monocarboxylic acids
• CPC Class Codes: C08L 53/02 of vinyl-aromatic monomers and conjugated dienes

Abstract

Temperature switchable pressure sensitive adhesives comprising an elastomer and a crystallizable abietic acid derivative as tackifier are described. These pressure sensitive adhesives exhibit a sharp reduction in peel strength when the temperature is raised above the switching temperature. The adhesive properties of these adhesives may be readily tuned by adjusting the ratio of the elastomer and the crystallizable tackifier, and by altering the crystallizabe group on the tackifier. The temperature switchable pressure sensitive adhesives have use in medical, consumer, and industrial applications.

Claims

1. A composition comprising:

a) at least one elastomer; and

b) at least one crystallizable abietic acid derivative-based tackifier having the formula;

2. The composition according to claim 1 wherein the crystallizable abietic acid derivative-based tackifier has the formula:

3. The composition according to claim 1, wherein the ratio of elastomer to crystallizable abietic acid derivative-based tackifier is 1:

3 by weight.

4. The composition according to claim 1, wherein the elastomer is an ABA block copolymer, wherein

a) A is a thermoplastic polystyrene end-block;

and

b) B is a rubber mid-block selected from the group consisting of polyisoprene, polybutadiene, and poly(ethylene/butylene);

wherein the elastomer has a thermoplastic polystyrene end-block content of about 14% to about 30% by weight.

5. The composition according to claim 4, wherein the ABA block copolymer is a styrene-isoprene-styrene triblock copolymer having a styrene content of about 14% to about 22% by weight.

6. The composition according to claim 4, wherein the ABA block copolymer is a styrene-isoprene-styrene triblock copolymer having a styrene content of about 22% by weight.

7. The composition according to claim 1 further comprising one or more additives selected from the group consisting of:

oils, inorganic extenders, stabilizers, antioxidants, plasticizers, flow modifiers, dyes, pigments, other tackifiers, heat reactive curing compounds, light reactive curing compounds, and wetting agents.

8. A temperature switchable adhesive assembly comprising:

a) a backing; and

b) a coating comprising the composition of claim 1.

9. The temperature switchable adhesive assembly according to claim 8, wherein the backing is selected from the group consisting of:

tapes, films of synthetic polymers, films of natural polymers, sheets of synthetic polymers, sheets of natural polymers, woven fabrics, nonwoven fabrics, and paper products.

10. The temperature switchable adhesive assembly according to claim 8, wherein the coating has a thickness of about 0.0127 mm to about 0.76 mm.

11. The temperature switchable adhesive assembly according to claim 8, wherein the assembly has a form selected from the group consisting of adhesive tapes, adhesive bandages, immobilization devices, wound dressings, transdermal delivery devices, EKG electrodes, masking tapes, stencils, envelopes, labels, stamps, wall paper, and floor tiles.

12. A method for imparting temperature switchable properties to an elastomer comprising the steps of:

a) providing at least one elastomer; and

b) mixing the at least one elastomer with at least one crystallizable abietic acid derivative-based tackifier having the formula;

13. The method according to according to claim 12 wherein the crystallizable abietic acid derivative-based tackifier has the formula:

14. The method according to claim 12, wherein the ratio of elastomer to crystallizable abietic acid derivative-based tackifier is 1:

3 by weight.

15. The method according to claim 12, wherein the elastomer is an ABA block copolymer, wherein

a) A is a thermoplastic polystyrene end-block;

and

b) B is a rubber mid-block selected from the group consisting of polyisoprene, polybutadiene, and poly(ethylene/butylene);

wherein the elastomer has a thermoplastic polystyrene end-block content of about 14% to about 30% by weight.

16. The method according to claim 15, wherein the ABA block copolymer is a styrene-isoprene-styrene triblock copolymer having a styrene content of about 14% to about 22% by weight.

17. The method according to claim 15, wherein the ABA block copolymer is a styrene-isoprene-styrene triblock copolymer having a styrene content of about 22% by weight.