Hot melt adhesives containing styrene butadiene block copolymer

• US 8,378,015 B2
• Filed: 02/15/2010
• Issued: 02/19/2013
• Est. Priority Date: 08/17/2007
• Status: Active Grant

• Current Assignee: Henkel AG & Co KGaA
• Original Assignee: Henkel AG & Co KGaA
• Inventors: He, Qiwei, Hu, Yuhong, Pollock, Alethea, Mehaffy, Justin, Harwell, Michael G.
• Primary Examiner(s): Mulcahy, Peter D
• Application Number:
  US12/705,742
• Publication Number:
  US 20100210163A1
• Time in Patent Office: 1,100 Days
• Field of Search: 524/505, 524/575, 428/375, 428/521
• US Class Current: 524/505
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• 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: C08L 53/02 of vinyl-aromatic monomers and conjugated dienes
• CPC Class Codes: C08L 53/025 modified
• CPC Class Codes: C09J 153/02 Vinyl aromatic monomers and conjugated dienes
• CPC Class Codes: C09J 153/025 modified
• CPC Class Codes: Y10T 428/2883 including addition polymer of diene monomer [e.g., SBR, SIS, etc.]
• CPC Class Codes: Y10T 428/2933 Coated or with bond, impregnation or core
• CPC Class Codes: Y10T 428/31931 Polyene monomer-containing
• CPC Class Codes: Y10T 442/2738 Coating or impregnation intended to function as an adhesive to solid surfaces subsequently associated therewith

Abstract

Hot melt adhesive compositions containing hyper-branched SBS block copolymers and end use applications thereof. The hyper-branched SBS is characterized in having a ratio between light-scattering molecular weight (of non-di-block polymer) and GPC molecular weight (of non-di-block polymer) greater than 1.4 and having ratio between light scattering molecular weight molecular weight (of non-di-block polymer) and light scattering molecular weight molecular weight (of di-block polymer) greater than 5. The ratio between light scattering molecular weight MW (of non-di-block polymer) and light scattering molecular weight MW (of di-block polymer) also defines the number of arms for the hyper branched structure. The weight average molecular weight of each arm of the hyper-branched SBS block copolymer is less than about 100,000. These are multipurpose adhesives finding utility as packaging, labeling, construction and positioning adhesives, and are particularly well suited for use as elastic attachment adhesives in the manufacture of elastic-containing products, such as disposable absorbent elastic articles.

Claims

1. A hot melt adhesive comprising from about 18 to about 40 wt %, based on the total weight of the adhesive, of a hyper-branched polystyrene-polybutadiene-polystyrene (SBS) block copolymer having (i) at least about 13 arms and (ii) a di-block percentage of from about 25% to about 75% and a tackifying resin,

wherein said hyper-branched SBS is characterized in having a ratio between light-scattering molecular weight (of non-di-block polymer) and GPC molecular weight (of non-di-block polymer) greater than 1.4 and having ratio between light scattering molecular weight molecular weight (of non-di-block polymer) and light scattering molecular weight molecular weight (of di-block polymer) greater than 5, and wherein the weight average molecular weight of each arm of the hyper-branched SBS block copolymer is less than about 100,000

wherein said hot melt adhesive application temperature ranges from about 250°

F. to about 325°

F. and said hot melt adhesive shear adhesion failure temperature is at least 10°

F. higher than a hot melt adhesive without the hyper-branched SBS.

2. The adhesive of claim 1 wherein the weight average molecular weight of each arm of the hyper-branched SBS block copolymer is between about 20,000 to about 80,000.

3. The adhesive of claim 1 further comprising a linear, or radial, or random block copolymer.

4. The adhesive of claim 3 wherein the hyper-branched SBS block copolymer has a di-block percentage of less than about 50%.

5. The adhesive of claim 1 wherein the styrene content of the hyper-branched SBS block copolymer is from about 20 wt % to about 50 wt %.

6. The adhesive of claim 5 which is pressure sensitive adhesive.

7. The adhesive of claim 3 wherein the linear, radial or random block copolymer is selected from the group consisting of styrene-isoprene-styrene, styrene-butadiene-styrene, styrene-isobutylene styrene, styrene-b-ethylene/butylene-b-stryrene, styrene-b-ethylene/propylene-b-styrene, styrene-butadiene random copolymer and combinations thereof.

8. The adhesive of claim 1 wherein the hyper-branched SBS block comprises at least about 14 arms.

9. The adhesives of claim 1 further comprising a wax.

10. The adhesive of claim 1 further comprising a liquid plasticizer.

11. An article of manufacture comprising the hot melt adhesive of claim 1 and a substrate.

12. The article of claim 11 wherein said substrate comprises an elastomeric fiber.

13. The article of claim 11 wherein said substrate is a nonwoven substrate.

14. The article of claim 12 which is a disposable elastic article.

15. The article of claim 13 which is a diaper.

16. The article of claim 11 wherein said substrate is a packaging substrate.

17. The article of claim 11 which is a pressure sensitive adhesive article.

18. The article of claim 17 which is a tape or label.