Abstract: A water-base erasable ink composition for use in marking pens which comprises:(a) water as a solvent;(b) a colorant dispersed or dissolved in the water in an amount of 0.5-20% by weight:(c) a water soluble polyvinyl acetal resin as a film-forming agent in an amount of 0.1-15% by weight;and(d) an aqueous emulsion of an aliphatic carboxylic acid ester which is liquid and nonvolatile or only slightly volatile at room temperatures as a separating agent in a dry amount of 1-20% by weight.The ink composition preferably further comprises a polyoxyethylene polyoxypropylene block copolymer, or a lanoline derivative, in particular, ethoxylated cholesterol or ethoxylated isocholesterol, or both of these, as a writing separation assistant.

Abstract: An erasable ink composition for writing on an impervious writing surface comprising an organic solvent, a resin, a pigment, and a separating agent which comprises:(a) a polyoxyethylene polyoxypropylene block copolymer, as a first separating agent, which is liquid at normal temperatures in an amount of 5-20% by weight, and(b) at least one organic compound selected from the group consisting of a carboxylic acid ester, a polyoxypropylene monoalkyl ether and a polyoxyethylene polyoxypropylene monoalkyl ether, as a second separating agent, which is liquid at normal temperatures in an amount of 2-10% by weight.

Abstract: An erasable ink composition for writing on an impervious writing surface comprising an organic solvent, a resin, a pigment, and a separating agent which comprises a polyoxyethylene polyoxypropylene monoalkyl ether which is liquid at normal temperatures in an amount of 5-20% by weight, and optionally at least one organic compound selected from the group consisting of a carboxylic acid ester and a polyoxypropylene monoalkyl ether which is liquid at normal temperatures in an amount of 2-10% by weight in conjunction.

Abstract: Disclosed is an ink composition including a coloring agent and an alcohol solvent, the composition being characterized in that the composition contains a sucrose benzoate represented by the formulaSuc(C.sub.6 H.sub.5 COO).sub.nin which Suc is a sucrose residue of the formula C.sub.12 H.sub.22-n O.sub.11-n and n is 6 to 8.

Abstract: 1. An erasable ink composition for writing on an impervious writing surface to form thereon a writing or marking which is erasable by wiping the surface; the composition comprising:about 40-90% by weight of a volatile organic solvent;about 1-20% by weight of a colorant;about 0.5-30% by weight of a resin which is soluble in the organic solvent; andabout 1-25% by weight of a fatty acid ester of trimethylolalkane of the general formula ##STR1## wherein R.sup.1 represents an alkyl of 1-3 carbons, R.sup.2 and R.sup.3 represent independently hydrogen or an alkyl of 1-21 carbons, and R.sup.4 represents an alkyl of 3-21 carbons.

Abstract: An ink composition for a marking pen is disclosed which permits smooth writing even after a long period of standing of the pen with no cap. The ink composition comprises an organic solvent, a pigment, a resin and at least one additive selected from the group consisting of a glyceride of specified structure, and an alkylamide alcohol of specified structure and a sorbitan fatty acid ester.An erasable ink composition for writing on a writing surface such as one of resin is also disclosed, which further includes, in addition to the above, a separating agent which is a non-volatile or only slightly volatile liquid or semi-solid at normal temperatures and has a lower vapor pressure than the solvent, and is soluble in the solvent.

Abstract: An ink composition for writing on an absorbent or pervious writing surface to form thereon a writing or marking composed of an inner portion of a first color with outer contour portions therearound of a second color, which composition comprises:a polar organic solvent,a nonpolar organic solvent which is miscible with the polar organic solvent,a first dyestuff which is soluble both in the polar organic solvent and a mixture of the polar organic solvent and the nonpolar organic solvent, but which is insoluble in the nonpolar organic solvent, anda second dyestuff which is soluble both in the nonpolar organic solvent and a mixture of the polar organic solvent and the nonpolar organic solvent, the second dyestuff being different in color from the first dye-stuff,whereby the first dyestuff forms in conjunction with the second dyestuff the inner portion of the first color based on the first and the second dyestuffs, and the second dyestuff forms the outer contour portions of the second color based on the second dyes