The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 02, 1997
Filed:
Mar. 14, 1996
Ronald B Birkholz, White Bear Lake, MN (US);
Mark E Schwartz, Mahtomedi, MN (US);
United States Postal Service, Washington, DC (US);
Abstract
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.