Release agent for linerless pressure sensitive postage stamps
US5663227A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 1996 |
| Grant date | Sep 2, 1997 |
| Priority date | — |
| Expiry date | Mar 14, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/1476
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.