The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 11, 1997
Filed:
May. 19, 1995
Takeyuki Yamamoto, Hiratsuka, JP;
Yasuyuki Sugimoto, Hiratsuka, JP;
Itaru Wakagi, Kanagawa, JP;
Shinichi Murakata, Kanagawa, JP;
Yasuzo Murata, Kanagawa, JP;
Kabushiki Kaisha Pilot, Tokyo, JP;
Abstract
A ballpoint pen contains an aqueous ink composition into which ink is directly filled. The pen is free from ink dripping and has improved writing performance. The aqueous ink composition is directly filled into an ink reservoir tube equipped with a ballpoint pen tip. The aqueous ink composition includes (a) an aqueous medium, (b) a pigment and (c) a carboxyl group-containing crosslinked hydrophilic polymer. The hydrophilic polymer swells and disperses in a gel state in the form of particles having a particle diameter of 0.5 to 10 .mu.m. The polymer is crosslinked with a crosslinkable monomer having at least two polymerizable unsaturated groups in an amount of 0.5 mol % or more based on the total of a carboxyl group-containing monomer and a copolymerizable monoethylenic monomer used together, if desired. The ink reservoir tube tip has a clearance between a ball and a ball receiver in the range of 10 to 40 .mu.m.