Self-adherent foam strip
SUMMARY OF THE INVENTION 
     This invention relates to foam strips and will have application to foam strips which adhere to glass and similar smooth surfaces without a separative adhesive. 
     Laboratory equipment is notoriously difficult to handle due to the smooth surface of glass. Such equipment is also very expensive. The foam strip of this invention is formed of a self-adherent PVC foam which has excess plasticizer incorporated therein. The foam is cast on a glossy surface release liner which further enhances the self-adherent properties of the strip. 
     Accordingly, it is an object of this invention to provide for a self-adherent foam strip. 
     Another object is to provide for a foam strip which adheres to glass and other smooth surfaces without a separate adhesive. 
     Another object is to provide a foam strip for gripping laboratory equipment. 
     Other objects will become apparent upon a reading of the folowing description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the foam strip of this invention shown being removed from its release liner. 
     FIG. 2 is a perspective view of the strip in use on a laboratory test tube. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment herein described is not intended to be exhaustive or to limit the invention to the precise form disclosed. It is chosen and described to explain the principles of the invention and its application and practical use so that others skilled in the art might utilize its teachings. 
     Referring to FIG. 1, reference numeral 10 refers generally to the foam tape strip of this invention. Strip 10 includes a single layer 12 of a foamed resin, such as PVC, polyurethane, or the like. Layer 12 is cast on a release liner 14 which has at least one smooth glossy surface 16. Layer 12 is generally formed by mixing the resin with an amount of plasticizer in excess of the amount needed to soften the resin. Layer 12 is then cast directly onto glossy surface 16 of release liner 14, which prevents bleeding of the plasticizer and allows foam layer to be unwound without adhering to itself. 
     FIG. 2 illustrates one of many possible applications of foam strip 10. After layer 12 is removed from release liner 14 and cut to size, layer 12 is wrapped around test tube 18 with the layer adhering to the smooth outer surface of the test tube. This adherence facilitates gripping of the tube 18 by hand or with conventional gripping tools such as tongs (not shown). Layer 12 also cushions tube 18 against breakage when dropped. 
     The following example is indicative of the process and materials used in forming strip 10. 
     EXAMPLE 
     The following compounds were combined to form a homogenous mixture: 
     
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Foamable PVC resin   100 parts by weight                                  
Phthalate plasticizer                                                     
                     140 parts by weight                                  
Blowing agent plasticizer blend                                           
                     14.4 parts by weight                                 
Activator stabilizer 1.5 parts by weight                                  
Cell stabilizer      1.0 parts by weight                                  
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     The above materials are disclosed in my U.S. Pat. No. 4,806,404, incorporated herein by reference. The mixture was cast at a height of 0.025 inches on the glossy side of a heavy density release liner and expanded by heating to 385° F. After the strip was allowed to cool, a six inch strip was cut and the foam tape peeled from the release liner and wrapped about a test tube. The tape adhered to the smooth surface of the tube until peeled off. 
     It is understood that the invention is not limited by the above details, but may be modified within the scope of the following claims.