Minnesota Mining and Manufacturing Company

United States Postal Service

Ronald B Birkholz

James J Pedginski

Mark E Schwartz

Richard R Riter

Mark D Glad

An improved release agent for linerless pressure sensitive postage stamps, comprising a low adhesion backsize, preferably organo polysiloxane polyurea block copolymer, as disclosed by Tushaus, et al. (U.S. Pat. No. 5,290,615), containing therein a dispersion of calcium carbonate in the range of 2 to 7 percent by weight, and polyvinyl pyrrolidone in the range of 4 to 10 percent. The combined level of both additives to said low adhesion backsize is about 8 to 12 percent. The preferred levels of each additive are: polyvinyl pyrrolidone at 4 percent and calcium carbonate at 4 percent, to achieve a desired minimum drying time for cancellation ink imposed upon a surface of said release agent.

Release agent for linerless pressure sensitive postage stamps

A tape comprising a biaxially-oriented backing made from a polymeric film bearing on one major surface thereof a layer of pressure-sensitive adhesive and on the other major surface thereof a layer of low-adhesion backsize composition. The backing and the layer of pressure-sensitive adhesive intermix so as to form a commingled layer between them. This invention also provides a process of preparing pressure-sensitive adhesive tape comprising the steps of (1) providing an extruded polymeric film backing, (2) orienting said backing in the machine direction, (3) applying a low-adhesion backsize layer to one major surface of said backing, (4) applying a pressure-sensitive adhesive layer to the major surface of said backing not bearing the low-adhesion backsize layer, (5) orienting the layer-bearing backing in the transverse direction by heating and cross-stretching the layer-bearing backing, (6) winding the machine direction oriented, transverse direction oriented, layer-bearing backing onto a roll, and (7) optionally, converting the machine direction oriented, transverse direction oriented, layer-bearing backing to form a tape.

Pressure-sensitive adhesive tape and a process for producing same

This invention provides a normally tacky pressure-sensitive adhesive composition comprising (1) a radial teleblock copolymer having at least three monoalkenyl arene polymer blocks and a branched elastomeric conjugated diene polymer block, (2) a tackifying resin, and (3) from about 5 to about 20 parts by weight extending oil per 100 parts by weight of radial copolymer. The copolymer preferably has a molecular weight of about 180,000 to about 250,000, as expressed in polystyrene equivalent molecular weight units. The monoalkenyl arene polymer blocks preferably comprise from about 17% to about 23% by weight of the total molecular weight of the copolymer. The preferred polymer for the monoalkenyl arene block is polystyrene; the preferred polymer for the elastomeric conjugated diene block is polyisoprene.

Pressure-sensitive adhesive composition having high shear strength

A tape comprising a biaxially-oriented backing made from a polymeric film bearing on one major surface thereof a layer of pressure-sensitive adhesive and on the other major surface thereof a layer of low-adhesive backsize composition. The backing and the layer of pressure-sensitive adhesive intermix so as to form a commingled layer between them. This invention also provides a process of preparing pressure-sensitive adhesive tape comprising the steps of (1) providing an extruded polymeric film backing, (2) orienting said backing in the machine direction, (3) applying a low-adhesive backsize layer to one major surface of said backing, (4) applying a pressure-sensitive adhesive layer to the major surface of said backing not bearing the low-adhesion backsize layer, (5) orienting the layer-bearing backing in the transverse direction by heating and cross-stretching the layer-bearing backing, (6) winding the machine direction oriented, transverse direction oriented, layer-bearing backing onto a roll, and (7) optionally, converting the machine direction oriented, transverse direction oriented, layer-bearing backing to form a tape.

Processs for producing pressure-sensitive adhesive tape

A label for application to a support surface. The label includes a moisture dissipative layer applied to a major surface of a sheet member. A layer of pressure sensitive adhesive is applied to the moisture dissipative layer opposite the sheet member for securing the label to a support surface. The label may be removed from the support surface without damage to the label by dissipating the moisture dissipative layer.

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White Bear Lake, MN, United States of America

Ronald B Birkholz