Adhesive compounds

#This disclosure relates to multiphase compositions of matter comprising at least an acrylic phase and a hydrocarbon phase, and more specifically to pressure sensitive adhesive compositions of matter of an acrylic-hydrocarbon polymer and an additional hydrocarbon component which has a molecular weight of at least 1,000 and may include one or both of an oligomeric hydrocarbon and a polymeric hydrocarbon.

#Pressure sensitive adhesives (“PSAs”), as commonly understood in the art and used herein, are typically viscoelastic materials that adhere instantaneously to most substrates with the application of slight pressure and remain permanently tacky. PSAs are finding increasingly more challenging uses as they become stronger and easier to apply. Such PSAs have now found many uses in industrial applications and are increasingly being favored by automobile manufacturers for mounting various parts of an automobile, from dashboard parts to body panels.

#Low surface energy (“LSE”) materials such as polypropylene and steel coated with LSE paints are increasingly used in the manufacture of automobiles. LSE materials also are increasingly used in consumer electronic applications. In the automotive industry, for example, parts such as body side moldings and weather seal foams are bonded to the substrates, typically polypropylene and painted steel, through the use of such PSAs. Clearly, such applications require not just high cohesive strength but high adhesion to LSE/non-polar surfaces as well as resistance to elevated temperatures and good ultraviolet (“UV”) light resistance and aging properties.

#One embodiment of the invention provides a multi-phase system or composition that includes at least a continuous, acrylic phase and a discontinuous, hydrocarbon phase that consists preferably of saturated or mostly saturated hydrocarbon macromers such as olefins. A key recognition of this embodiment is that the addition of hydrocarbon compounds, which preferably have a molecular weight of at least 1,000, to such multi-phase composition enhances their adhesion strength as well as, unexpectedly, their cohesive (i.e., internal) strength. The hydrocarbon compounds, can be added to the hydrocarbon phase of the multi-phase composition, the acrylic phase, to both the hydrocarbon and acrylic phase, or as a separate, additional hydrocarbon phase.

#In further embodiments, the PSA disclosed herein can be prepared with additional phases, chosen to impart additional properties to the compound. For instance, a silicone phase can be added to enhance adhesion to silicone substrates. The hydrocarbon and acrylic phases can be chosen to form a graft copolymer that will support any number of phases desired to be contained in the PSA. It is understood that these phases can exhibit microphase separation.

#In one embodiment, the adhesive polymers of the invention are rubber-acrylic hybrid polymers having an acrylic polymer backbone grafted with hydrocarbon macromers and further including hydrocarbon oligomers and/or hydrocarbon polymers. Hydrocarbon macromers that can be used include, but are not limited to, olefinic hydrocarbons such as ethylene-butylene macromers, ethylene-propylene macromers ethylene-butylene-propylene macromers, and isobutylene macromers, and can range in molecular weight from about 2,000 to about 30,000. Specific, commercially available examples of a hydrocarbon macromer that can be used is L-1253, a fully hydrogenated ethylene-butylene macromer with a molecular weight of approximately 6000 that is manufactured by Kuraray Co., Ltd. of Tokyo, Japan. Other non-olefinic macromers that can form a separate phase from the acrylic backbone also can be incorporated into the adhesive polymer, and include, but are not limited to, poly methyl methacrylate (“PMMA”) available from Lucite International Ltd. of Southampton, United Kingdom; poly styrene (“PS”) available from Bimax, Polymer Chemistry Innovations Inc. of Tucson, Ariz.; poly dimethylsiloxane (“PDMS”); poly ethyleneoxide (“PE OX”); and poly propyleneoxide (“PP OX”). Those macromers also can be added as an additional phase to the hydrocarbon macromers.