Non-erasable pencil lead
US5716434A · kind A · utility
8Cited by
4References
12Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jul 31, 1996 |
| Grant date | Feb 10, 1998 |
| Priority date | — |
| Expiry date | Jul 31, 2016 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09D13/00
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Provided is a non-erasable pencil lead for a natural pencil and a mechanical pencil, characterized in that the pores of a baked pencil lead are impregnated with an unsaturated compound containing an unsaturated group having an iodine value of at least 130 or more, wherein an antioxidant, an oxidative polymerization catalyst and/or a photosensitizer can be added in addition to the unsaturated compound.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.