Temperature switchable adhesives comprising a crystallizable oil

• US 8,828,181 B2
• Filed: 04/30/2010
• Issued: 09/09/2014
• Est. Priority Date: 04/30/2010
• Status: Active Grant

• Current Assignee: Dupont US Holding, LLC (International Flavors & Fragrances Incorporated)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Burch, Robert Ray
• Primary Examiner(s): ORLANDO, MICHAEL N
• Application Number:
  US12/771,078
• Publication Number:
  US 20110265949A1
• Time in Patent Office: 1,593 Days
• Field of Search: 156/334, 524/285, 524/525
• US Class Current: 156/334
• CPC Class Codes: C08K 5/01 Hydrocarbons C08K5/0091 takes precedence
• CPC Class Codes: C08K 5/09 Carboxylic acids; Metal salts thereof; Anhydrides thereof
• CPC Class Codes: C09J 11/00 Features of adhesives not provided for in group C09J9/00, e.g. additives
• CPC Class Codes: C09J 11/06 organic
• CPC Class Codes: C09J 153/02 Vinyl aromatic monomers and conjugated dienes
• CPC Class Codes: C09J 2301/312 parameters being the characterizing feature
• CPC Class Codes: C09J 2453/00 Presence of block copolymer
• CPC Class Codes: C09J 2491/00 Presence of oils, fats or waxes
• CPC Class Codes: C09J 7/387 Block-copolymers
• CPC Class Codes: C09J 9/00 Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks C09J7/00 takes precedence
• CPC Class Codes: Y10T 156/1911 Heating or cooling delaminating means [e.g., melting means, freezing means, etc.]
• CPC Class Codes: Y10T 428/2826 Synthetic resin or polymer
• CPC Class Codes: Y10T 442/2746 Heat-activatable adhesive

Abstract

Temperature switchable adhesives formed by combining a pressure sensitive adhesive, which does not exhibit temperature switchable properties, with a crystallizable oil are described. These temperature switchable 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, tackifier, and the crystallizable oil, and by choosing different crystallizable oils. The temperature switchable adhesives have use in medical, consumer, and industrial applications.

Claims

1. A temperature switchable adhesive composition comprising:

a) at least one pressure sensitive adhesive, which does not exhibit temperature switchable properties, having a rubbery plateau between a first temperature T1 and a second temperature T2, said pressure sensitive adhesive comprising at least one elastomer selected from the group consisting of thermoplastic rubbers, natural rubbers, butyl rubbers, polyisobutylene polymers, vinyl ether polymers, ethylene/acrylic copolymers, silicone-based rubbers, and acrylics; and

b) at least one crystallizable oil having a crystalline melting point between T1 and T2 in an amount of at least about 20% by weight of the composition;

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 of the block copolymer; and

wherein if the elastomer is selected from the group consisting of thermoplastic rubbers, natural rubbers, butyl rubbers, polyisobutylene polymers, vinyl ether polymers, ethylene/acrylic copolymers, and silicone-based rubbers, the pressure sensitive adhesive further comprises at least one tackifier.

2. The temperature switchable adhesive composition according to claim 1, wherein the composition comprises a ratio of elastomer plus tackifier to crystallizable oil of about 0.66:

1 to about 5.0;

1 by weight.

3. The temperature switchable adhesive composition according to claim 1, wherein the ABA block copolymer is a styrene-isoprene-styrene triblock copolymer having a styrene content of about 14% to about 22% by weight.

4. The temperature switchable adhesive composition according to claim 1 wherein the tackifier is selected from the group consisting of poly-β

-pinene, abietic acid, abietic acid esters, hydrogenated abietic acid, hydrogenated abietic acid esters, poly-a-pinene, neoabietic acid, palustric acid, dihydroabietic acid, dehydroabietic acid, pimaric acid, isopimaric acid, styrene, methyl styrene, indene, methyl indene, oligomers of diclyopentadienes, and oligomers of butadienes.

5. The temperature switchable adhesive composition according to claim 4 wherein the tackifier is poly-β

-pinene or abietic acid.

6. The temperature switchable adhesive composition according to claim 1 wherein the crystallizable oil is present in an amount of at least about 25% by weight of the composition.

7. The temperature switchable adhesive composition according to claim 1 wherein the crystallizable oil is selected from the group consisting of:

hexadecane, 1-hexadecanol, 1-tetradecane, 1-tetradecanol, octadecane, and octadecanol.

8. The temperature switchable adhesive composition according to claim 1 wherein the elastomer is an acrylic and the pressure sensitive adhesive is self-tackifying.

9. A temperature switchable adhesive assembly comprising:

a) a backing; and

b) a coating comprising the temperature switchable adhesive composition of claim 1.

10. The temperature switchable adhesive assembly according to claim 9, 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.

11. The temperature switchable adhesive assembly according to claim 9, 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 a pressure sensitive adhesive, said method comprising the steps of:

a) providing at least one pressure sensitive adhesive, which does not exhibit temperature switchable properties, having a rubbery plateau between a first temperature T1 and a second temperature T2, said pressure sensitive adhesive comprising at least one elastomer selected from the group consisting of thermoplastic rubbers, natural rubbers, butyl rubbers, polyisobutylene polymers, vinyl ether polymers, ethylene/acrylic copolymers, silicone-based rubbers, and acrylics; and

b) mixing the at least one pressure sensitive adhesive with at least one crystallizable oil having a crystalline melting point between T1 and T2, wherein the crystallizable oil is in an amount of at least about 20% by weight;

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 of the block copolymer; and

wherein if the elastomer is selected from the group consisting of thermoplastic rubbers, natural rubbers, butyl rubbers, polyisobutylene polymers, vinyl ether polymers, ethylene/acrylic copolymers, and silicone-based rubbers, the pressure sensitive adhesive further comprises at least one tackifier.

13. The method according to claim 12 wherein the pressure sensitive adhesive comprises a ratio of elastomer plus tackifier to crystallizable oil of about 0.66:

1 to about 5.0;

1 by weight.

14. The method according to claim 12 wherein the crystallizable oil is selected from the group consisting of hexadecane, 1-hexadecanol, 1-tetradecane, 1-tetradecanol, octadecane, and octadecanol.