Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
1998-11-12
2001-01-23
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S374000, C528S376000, C156S060000, C156S272200, C156S273300, C156S275500, C427S516000
Reexamination Certificate
active
06177540
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the use of star-branched polymers in pressure sensitive adhesive applications.
BACKGROUND OF THE INVENTION
Star-branched polymers, also known as radial polymers, are characterized by having three or more polymeric arms emanating from a central core. These polymers can be prepared by various polymerization procedures such as anionic, cationic, and free radical mechanisms. The star polymers are usually formed by using either multifunctional initiators, multifunctional chain transfer agents, or multifunctional coupling agents. The star polymers have unique properties including: narrow molecular weight distributions; low viscosities at low molecular weights or in solution due to their compact structures; and high viscosities at high molecular weights due to extensive entanglements.
U.S. Pat. No. 3,769,254 discloses pressure sensitive adhesives prepared from linear polymers of acrylic polymers containing monomers with reactive hydrogen groups. In general, high molecular weight linear polymers are usually used in high performance applications. Such polymers have solution viscosities proportional to their molecular weight. Attempts to lower the solution viscosities by reducing molecular weight results in a reduction in adhesive properties which makes them difficult to use as hot melts for high performance and coating applications. In linear systems, these lost properties cannot be recovered by crosslinking.
U.S. Pat. No. 5,679,762 discloses block star polymers which overcome some of the problems associated with a linear system. This patent is limited to block polymers which provide phase separation to attain the desired adhesive properties.
SUMMARY OF THE INVENTION
This invention relates to pressure sensitive applications comprising star polymers. Specifically to pressure sensitive applications comprising random star polymers comprising an olefinic monomer containing one or more functional groups which can be crosslinked by reaction with multifunctional crosslinking agents.
The pressure sensitive adhesive compositions of the present invention comprise an adhesive polymer formed by the reaction of a multifunctional crosslinker with a star polymer. Optional components of the adhesive polymer include other monomers containing an additional copolymerizable ethylenically unsaturated linkage as the only reactive functional group. The preferred multifunctional crosslinkers are metal compounds. With the star polymers of the present invention, high solids, low viscosity systems can be prepared with good adhesive properties and improved coatability.
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Gore Christopher G.
Hariharan Deepak
Harlan Robert D.
Schoenberg Jules E.
Shah Smita M.
McClendon S L.
National Starch and Chemical Investment Holding Corporation
Roland Thomas F.
Seidleck James J.
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