Hot melt adhesive based on acrylic block copolymers

• US 7,714,052 B2
• Filed: 04/18/2008
• Issued: 05/11/2010
• Est. Priority Date: 12/21/2002
• Status: Expired due to Term

• Current Assignee: Henkel AG & Co KGaA
• Original Assignee: Henkel AG & Co KGaA
• Inventors: Paul, Charles W., Meisner, Cynthia L.
• Primary Examiner(s): Lipman; Bernard
• Application Number:
  US12/105,838
• Publication Number:
  US 20080269404A1
• Time in Patent Office: 753 Days
• Field of Search: 524/376, 524/377, 524/505
• US Class Current: 524/376
• CPC Class Codes: C08F 297/026 polymerising acrylic acid, methacrylic acid or derivatives thereof
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C09J 153/00 Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers

Abstract

High performance, low viscosity hot melt adhesives are obtained using acrylic block copolymers. The level of acrylic block copolymer in the adhesive formulation is less than 50% by weight.

Claims

1. A pressure sensitive adhesive consisting essentially of, based on the weight of the adhesive composition, from about 20 to 35 wt % of block copolymer, said block copolymer comprising an acrylic block copolymer having the formula:

—

[A1]—

[B]—

[A2]—

wherein A1 and A2 each represents a polymer block having a glass transition temperature (Tg) of greater than about 30°

C., and B represents a polymer block having a Tg of less than about 20°

C.

2. The adhesive of claim 1 wherein the adhesive further comprises a tackifier and/or diluent.

3. The adhesive of claim 1 wherein polymer block B is present in amounts of at least about 50 weight %.

4. The adhesive of claim 1 wherein A1 and A2 are methyl methacrylate and B is n-butyl acrylate.

5. The adhesive of claim 2 wherein said diluent is polypropylene glycol.

6. The adhesive of claim 1 wherein the block copolymer is prepared by anionic polymerization.

7. The adhesive of claim 2 wherein the total amount of tackifier and diluent in the adhesive exceeds the amount of block copolymer.

8. The adhesive of claim 7 wherein the adhesive comprises from about 35 to about 80 wt % of a tackifier, from about 10 to about 45 wt % of a diluent, and up to about 2 wt % of an antioxidant.

9. An article of manufacture comprising the adhesive of claim 1.

10. The article of claim 9 which is an adhesive tape.

11. The article of claim 10 which is a medical tape.