Abstract: The present disclosure relates to a method for producing polymer microparticles, this method including a step for polymerizing vinyl monomers in a hydrophilic solvent, which dissolves the vinyl monomers and a dispersion stabilizer but does not dissolve a polymer formed, in the presence of the dispersion stabilizer. The present disclosure is a method for producing these polymer microparticles, wherein the dispersion stabilizer contains a macromonomer having carboxyl groups and ethylenically unsaturated groups at an intermediate location in a molecular chain thereof, the macromonomer has, on average, 1.4 to 2.5 ethylenically unsaturated groups per molecule, and an average value of a carboxyl group content in the macromonomer is 0.5 meq/g to 2.5 meq/g.

Abstract: An erasable ink composition comprising water, a water-soluble organic solvent, and the following colorant, colorless resin particles and shear-thinning, viscosity-adjustment agent, characterized in that the colorless resin particles have a mean particle diameter smaller than that of the colorant and are contained in an amount larger than that of the colorant: (a) 3 to wt % (based on the whole ink) of colorless resin particles which are made of at least one resin selected from among acrylic resins, urethane resins, silicone resins and melamine resins and have a mean particle diameter of 0.10 to 10 ?m, (b) 1 to 40 wt % (based on the whole ink) of a colorant having a mean particle diameter of 2 ?m or above, and (c) 0.01 to 4 wt % (based on the whole ink) of a shear thinning, viscosity-adjustment agent.

Abstract: An erasable ink composition comprising water, a water-soluble organic solvent, and the following colorant, colorless resin particles and shear-thinning, viscosity-adjustment agent, characterized in that the colorless resin particles have a mean particle diameter smaller than that of the colorant and are contained in an amount larger than that of the colorant: (a) 3 to wt % (based on the whole ink) of colorless resin particles which are made of at least one resin selected from among acrylic resins, urethane resins, silicone resins and melamine resins and have a mean particle diameter of 0.10 to 10 ?m, (b) 1 to 40 wt % (based on the whole ink) of a colorant having a mean particle diameter of 2 ?m or above, and (c) 0.01 to 4 wt % (based on the whole ink) of a shear thinning, viscosity-adjustment agent.

Abstract: A polychromic ink composition depending on viewing angle comprises 0.5 to 40% by weight of cholesteric liquid crystal polymer particles whose maximum particle diameter is 1 to 200 &mgr;m, 1.0 to 30.0% by weight of binder resins, 0.05 to 20% by weight of pigments with a deep-colored coloring matter whose average particle diameter is 0.01 to 0.5 &mgr;m, 0.01 to 5.0% by weight of a shear-thinning property imparting agent, and water with respect to the total amount of the ink composition.

Abstract: The main object is to provide a water-based ink composition which is not only superior in hiding power but also has satisfactory writing properties. This invention relates to a water-based ink composition comprising a powder consisting of inorganic particles comprising at least one of aluminum oxide, titanium dioxide and boron nitride and water.

Abstract: The main object is to provide a water-based ink composition which is not only superior in hiding power but also has satisfactory writing properties. This invention relates to a water-based ink composition comprising a powder consisting of inorganic particles comprising at least one of aluminum oxide, titanium dioxide and boron nitride and water.

Abstract: A polychromic ink composition depending on viewing angle comprises 0.5 to 40% by weight of cholesteric liquid crystal polymer particles whose maximum particle diameter is 1 to 200 &mgr;m, 1.0 to 30.0% by weight of binder resins, 0.05 to 20% by weight of pigments with a deep-colored coloring matter whose average particle diameter is 0.01 to 0.5 &mgr;m, 0.01 to 5.0% by weight of a shear-thinning property imparting agent, and water with respect to the total amount of the ink composition.

Abstract: A water base erasable ink composition for use in marking pens which comprises:(a) water as a solvent;(b) a coloring agent;(c) an aqueous emulsion of at least one nonvolatile oily material which is liquid at room temperatures and is selected from the group consisting of aliphatic carboxylic acid esters, higher hydrocarbons and higher alcohols in a dry amount of 1-50% by weight;(d) a cyclodextrin or its derivative in an amount of 0.1-20% by weight; and(e) a resin which is film-forming at room temperatures.The ink composition has improved storability over a long period of time.