Pressure sensitive adhesive composition

#The present invention relates to adhesives, more specifically to pressure sensitive adhesives. In particular, the invention relates to pressure sensitive adhesives having favorable shear properties at elevated temperatures.

#Pressure sensitive adhesive (PSA) compositions are used in a wide variety of applications, including many assembly and manufacturing applications. Numerous applications require PSAs to support a load at elevated temperatures, typically in the range of greater than 70° C., for which high cohesive strength PSAs are required. A standard method of increasing cohesive strength at elevated temperatures is to chemically crosslink the PSA using irradiation processes, such as thermal radiation, ultraviolet (UV) radiation, gamma radiation, and electron beam (EB) radiation, etc. Although these processes improve cohesive strength, they often negatively impact other properties, including peel strength of the PSA.

#A need exists for an improved PSA with high cohesive strength that does not require chemical crosslinking. The present invention is directed to PSA compositions and to PSA articles containing the adhesive composition. The adhesive compositions of the invention generally demonstrate desirable cohesive strength at elevated temperatures. This cohesive strength can be at least as high as that obtained with chemical crosslinking. Thus, the adhesive composition provides many of the advantages of crosslinking without various disadvantages, such as excessive degradation of the adhesive and loss of adhesion.

#Other aspects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawing in which:

#FIG. 1 is an illustration of the temperature dependence of the elastic modulus (G′) for increasing concentrations of polyphenylene ether (PPO) in Isooctyl Acrylate/Acrylic Acid—derived copolymer grafted with a polystyrene-reinforcing moiety.

#FIG. 2 is an illustration of the peel force against a glass surface vs. peel rate for compositions having a 90:10 ratio of acrylate to styrene, a constant thickness of 28 μm and varying concentrations of PPO.

#While the invention is susceptible to various modifications and alternative forms, specifics thereof have been shown by way of example in the figure and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

#The present invention is directed to a PSA composition and to a PSA article such as a film or foam containing the adhesive composition. The adhesive composition has significant cohesive strength, especially at elevated temperatures.

#The ingredients of the PSA composition, methods of making the composition, and example compositions will now be discussed in greater detail.