Writing instrument
US6409408B1 · kind B1 · utility
13Cited by
3References
11Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jan 26, 2001 |
| Grant date | Jun 25, 2002 |
| Priority date | — |
| Expiry date | Jan 26, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09D11/16
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
Provided is a free ink type writing instrument having an ink tank part for storing an ink, in which an amount of the ink can visually be observed. The free ink type writing instrument is characterized by that the whole or a part of an internal surface part in contact with the ink in the ink tank part has a smaller critical surface tension than a surface tension of the ink, and a contact angle between the ink and the whole or a part of the internal surface part in contact with the ink in the ink tank part is 30° or more at a temperature of 25° C.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.