Pressure sensitive adhesive and its preparation

• US 6,887,919 B2
• Filed: 02/03/2003
• Issued: 05/03/2005
• Est. Priority Date: 03/19/2002
• Status: Expired due to Term

• Current Assignee: Tesa SE (maxingvest GmbH & Co. KGaA)
• Original Assignee: Tesa AG (maxingvest GmbH & Co. KGaA)
• Inventors: Krawinkel, Thorsten, Lühmann, Bernd, Bargmann, Renke
• Primary Examiner(s): Moore, Margaret G.
• Assistant Examiner(s): Zimmer, Marc S.
• Application Number:
  US10/357,069
• Publication Number:
  US 20030215660A1
• Time in Patent Office: 820 Days
• Field of Search: 525/88, 525/95, 525/901, 525/914, 156/334, 428/521, 522/111, 522/112
• US Class Current: 522/111
• CPC Class Codes: C08F 287/00 Macromolecular compounds obtained by polymerising monomers on to block polymers
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/24 Graft or block copolymers according to groups C08L51/00, C08L53/00 or C08L55/02; Derivatives thereof
• CPC Class Codes: C09J 151/006 grafted on to block copolymers containing at least one sequence of polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: C09J 153/02 Vinyl aromatic monomers and conjugated dienes
• CPC Class Codes: C09J 153/025 modified
• CPC Class Codes: C09J 2301/308 the adhesive tape or sheet losing adhesive strength when being stretched, e.g. stretch adhesive
• CPC Class Codes: C09J 2453/00 Presence of block copolymer
• CPC Class Codes: C09J 7/387 Block-copolymers
• CPC Class Codes: Y10S 528/901 Room temperature curable silicon-containing polymer
• CPC Class Codes: Y10T 428/1443 Aluminum
• CPC Class Codes: Y10T 428/31909 Next to second addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31931 Polyene monomer-containing

Abstract

A pressure sensitive adhesive composed of a mixture comprising

• a) a styrene block copolymer having a star-shaped structure and a molecular weight M_w of more than 300,000 g/mol, or having elastomer blocks which contain more than 30% by weight of 1,2-linked diene in their block structure, or both, and which is crosslinkable by exposure to UV-light or electron beams, and
• b) one or more block copolymers composed of vinylaromatic blocks and elastomer blocks, the block polyvinylaromatic content being greater than 20%, and
• c) one or more tackifier resins.

Claims

1. A double-sided stretchable pressure sensitive adhesive sheet strip, which, when bonded to a substrate is detachable from said substrate by stretching, said pressure sensitive adhesive sheet strip being formed from a composition comprising a mixture of:

a) a styrene block copolymer having a star-shaped structure and a molecular weight Mw of more than 300,000 g/mol, or having elastomer blocks which contain more than 30% by weight of 1,2-linked diene in their block structure, and which is crosslinkable by exposure to UV-light or electron beams, and

b) one or more block copolymers having polyvinylaromatic blocks and elastomer blocks, the polyvinylaromatic block content being greater than 20% by weight, and

c) one or more tackifier resins.

3. The adhesive as claimed in claim 1 or 2, wherein the block copolymers according to 1b) have polystyrene end blocks.

4. The adhesive as claimed in claim 1 or 2, wherein the block copolymers have a polyvinylaromatics fraction of from 20 to 40% by weight, and/or a triblock content of more than 60% by weight, or both.

5. The adhesive as claimed in claim 4, wherein said polyvinylaromatic fraction is from 25% to 35% by weight.

6. The adhesive as claimed in claim 4, wherein said triblock content is more than 75% by weight.

7. The adhesive as claimed in claim 1 or 2, wherein the styrene block copolymer according to 1a) comprises 1,2-linked polybutadiene or polyisoprene.

8. The adhesive as claimed in claim 1 or 2, wherein the styrene block copolymer is formed of styrene-butadiene block copolymer or styrene-isoprene block copolymer.

9. The adhesive as claimed in claim 1 or 2, wherein the styrene block copolymer has polydiene-containing elastomer blocks.

10. The adhesive as claimed in claim 9, wherein said polydiene-containing elastomer blocks are copolymers of two or more different 1,3-dienes.

11. The adhesive as claimed in claim 1 or 2, wherein the styrene block copolymer is functionalized.

12. The adhesive as claimed in claim 11, wherein said styrene block copolymer is functionalized by being maleic anhydride-modifid or silane-modified.

13. The adhesive as claimed in claim 1 or 2, comprising 20 to 70% by weight of styrene block copolymer, based on the weight of the adhesive.

14. The adhesive as claimed in claim 13, wherein said amount of styrene block copolymer is 30 to 60% by weight.

15. The adhesive as claimed in claim 14, wherein said amount of styrene block copolymer is 35 to 55% by weight.

16. The adhesive as claimed in claim 1 or 2, further comprising blend components selected from the group consisting of plasticizers, aging inhibitors, processing assistants, fillers, dyes, optical brighteners, and stabilizers.

17. The adhesive as claimed in claim 1 or 2, further comprising crosslinking promoters.

18. A method for producing a pressure sensitive adhesive sheet strip for providing a bond which can be parted again by stretching in the direction of the bond plane, which comprises applying the pressure sensitive adhesive of claim 1 or 3 to an elastically-stretchable backing.

19. A process for preparing the pressure sensitive adhesive for the pressure sensitive adhesive sheet strips according to claims 1 and 2, which comprises mixing

(i) a styrene block copolymer having a star-shaped structure and a molecular weight M_w of more than 300,000 g/mol, or having elastomer blocks containing more than 30% of 1,2-linked diene in the elastomer block structure, or both, and which is crosslinkable by exposure to UV-light or electron beams, and

(ii) one or more block copolymers composed of polyvinylaromatic blocks and elastomer blocks, the polyvinylaromatic block content being greater than 20%, and

(iii) one or more tackifier resins with elastomer blocks, and exposing the mixture to UV-light or electron beams.

2. A single-sided stretchable pressure sensitive adhesive sheet strip, the side opposite the adhesive side being neutralized, which, when bonded to a substrate is detachable from said substrate by stretching, said pressure sensitive adhesive sheet strip being formed from a composition comprising a mixture of:

a) a styrene block copolymer having a star-shaped structure and a molecular weight Mw of more than 300,000 g/mol, or having elastomer blocks which contain more than 30% by weight of 1,2-linked diene in their block structure, and which is crosslinkable by exposure to UV-light or electron beams, and

b) one or more block copolymers having polyvinylaromatic blocks and elastomer blocks, the polyvinylaromatic block content being greater than 20% by weight, and

c) one or more tackifier resins.