The Pilot Ink Co., Ltd.

Kabushiki Kaisha Pilot Corporation

Yoshiaki Okawara

Nobuo Sekine

Michiyuki Yasuda

Takehiko Yokosuka

Masashi Andoh

Takashi Wase

There is provided a friction body which is adapted to rub a thermochromic image or handwriting formed on a paper surface by use of thermochromic ink to thermally discolor the thermochromic image or handwriting by frictional heat resultant from rubbing, a thermal conductivity of a friction portion of the friction body is set to be within 0.05 W/(m&#xb7;K) to 50 W/(m&#xb7;K).

Friction body, writing instrument and writing instrument set

The present invention provides the ballpoint pen that precludes the possibility of the pipe portion bending at the joint thereof can be provided even if the outer diameter D is small. In the ballpoint pen having a ballpoint pen tip at a front end thereof, the ballpoint pen tip rotatably accommodating a ball at a front end of a pipe made of metal, an outwardly projecting pipe portion having a uniform thickness throughout the length thereof is arranged at a front end of the ballpoint pen tip, and if a length of the pipe portion is L, an outer diameter of the pipe portion is D, a relational expression 'L/D.ltoreq.4.0' is satisfied.

Ballpoint pen and cap therefor

Growing community of inventors

Nagoya, Japan

Yoshiaki Okawara