Spirodipyrans and chromogenic materials for copying processes
US3971808A · kind A · utility
32Cited by
3References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 7, 1974 |
| Grant date | Jul 27, 1976 |
| Priority date | — |
| Expiry date | May 7, 1994 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S8/919
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Spirodipyrans based on condensed pyrylium salts and 4-dialkylamino-2-hydroxybenzaldehydes, their manufacture and their use as chromogenic materials in pressure-sensitive recording materials, particularly copying papers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.