Mitsubishi Pencil Kabushiki Kaisha

Atsushi Iwasa

Kiyokazu Sakurai

Yasuaki Ogiwara

Takao Koyama

Hiroyuki Idogawa

Kazuhisa Kirita

A free-ink type writing instrument having a temporary ink collector having a sectionally combed configuration, between an ink tank chamber and an writing tip and inside the front barrel, wherein all or part of the gaps between neighboring combed teeth for retaining ink in the temporary ink collector are set equal to 0.15 mm or smaller, and the ink tank is charged with an ink having a surface tension equal to 30 mN/m or lower at 25&deg; C.

Free-ink type writing instrument

A free-ink type writing instrument includes: an ink tank for holding ink; a temporary ink collector for temporarily retaining the ink flowing out from the ink tank; a partitioning wall separating the ink tank and the temporary ink collector; and a pen core disposed from the ink tank, penetrating through the partitioning wall and the ink collector so as to allow ink to flow out from the ink tank, and is characterized in that the storage volume Vc of the ink collector and the ink tank volume Vo satisfy the relation Vc&gE;0.18 Vo.

Provided is a stable water base ink composition which has a sufficiently high concentration as ink for an ink jet-recording apparatus and writing instruments and prevents the recorded images and the written characters from being blurred or disappearing with water and sweat and which has such an excellent light fastness that the images and the characters do not deteriorate over a long period of time and does not cause a change in physical properties and precipitates. A water base dispersion liquid containing colored resin fine particles is prepared by emulsion-polymerizing a vinyl monomer in the presence of a hydrophobic dye and then diluted with water or a water soluble organic solvent, whereby the water base ink composition is produced.

Water base ink composition

Provided is an erasable ink comprising an emulsion liquid prepared by polymerizing a polymerizable monomer containing a conjugate diene compound in a solvent containing water in the presence of a dye and a surfactant, wherein the polymerizable monomer may contain a vinyl compound as well as a conjugate diene compound, and used are 0.01 to 100 parts by weight of the dye and 0.1 to 30 parts by weight of the surfactant each per 100 parts by weight of the polymerizable monomer.

Erasable ink

Provided is a colored resin fine particle water base dispersion liquid which can be a base material for an ink causing no precipitates and having storage stability. Further provided is a water base ink composition for an ink jet recording apparatus or a water base ink composition for a writing tool capable of providing recorded images or written characters and drawn lines which are clear and neither are blurred nor disappear due to water and sweat and which are so excellent in light fastness that they are not deteriorated over a long period of time, wherein the colored resin fine particle water base dispersion liquid is produced by mixing a water soluble basic dye with a mixed vinyl monomer containing a vinyl monomer having an acid functional group and emulsion-copolymerizing the above mixture.

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Tano-gun, Japan

Atsushi Iwasa