Paper pencil lead
US10308063B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 14, 2015 |
| Grant date | Jun 4, 2019 |
| Priority date | — |
| Expiry date | May 24, 2036 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09D13/00
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
The present invention concerns an extrudable, unexpanded paper pencil lead, comprising, by weight relative to the total weight of the lead, between 40 and 60%, and advantageously between 44 and 50%, of graphite; between 15 and 40%, and advantageously between 20 and 35%, of a polyolefin; between 5 and 15%, and advantageously between 6 and 10%, of a colorless mineral filler; between 5 and 20%, and advantageously between 5 and 15%, of carbon black coated with or mixed with a polyolefin wax or a polyolefin; between 0 and 16%, and advantageously between 5 and 15%, of an additive. It further concerns the paper pencil comprising a lead according to the invention.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.