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US 6,306,930 B1Granted
Erasable ink and water-base ballpoint pen using same
AssigneeSakura Color Products Corporation
InventorShinji Tsujio
Life of this patent
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AssigneeSakura Color Products Corporation
InventorShinji Tsujio
Estimating the term…
The invention provides an aqueous ink composition which can be erased relatively easily even after writing with a great tool force. The invention relates to (1) an erasable aqueous ink composition containing at least one colorant, characterized in that the colorant has a mean particle size of not less than 2 μm and that particles having a size of not more than 1.8 μm account for not more than 1.6% by weight of said colorant; (2) an erasable aqueous ink composition containing at least one colorant, characterized in that the colorant has a mean particle size of not more than 7 μm and that particles having a size of not less than 7 μm account for not more than 0.5% by weight of said colorant and (3) an erasable aqueous ink composition containing at least one colorant, characterized in that the colorant has a mean particle size of 2 to 7 μm, that particles having a size of not more than 1.8 μm account for not more than 1.6% by weight of said colorant and that particles having a size of not less than 7 μm account for not more than 0.5% by weight of said colorant.
An erasable aqueous ink composition comprising at least one colorant, wherein the ink composition is free of any film-fonning resin, and wherein sad colorant has a mean particle size of 2 to 7 μm, and wherein particles having a size of not more than 1.8 μm account for not more than 1.6% by weight of said colorant and wherein particles having a size of not less than 7 μm account for not more than 0.5% by weight of said colorant.
Dependencies are inferred from the claim text.