A lacquer composition is provided, comprising 20%-79.9% by weight, based on the total weight of the composition, of a thiol compound having two or more thiol groups, 20%-79.9% by weight, based on the total weight of the composition, of a compound having two or more carbon-carbon double bonds and 0.1%-10% by weight, based on the total weight of the composition, of a separating agent having an alkyl radical having 4-20 carbon atoms, where the alkyl radical is unsubstituted or fluorine-substituted and the alkyl radical is bonded to a functional group. Also provided are the use of this lacquer composition as a protective lacquer on an optical surface of an optical element in the production of the optical element, and an optical element comprising the protective lacquer.

Provided are an ink composition for writing instruments which has a good solubility of a coloring material in an ink solvent and which is less liable to cause bleeding and feathering on the written lines and is improved in a water resistance, and a coloring material used for preparing the above ink composition. The coloring material includes a material obtained by adding at least one selected from a leuco dye, a halochromic dye and a photochromic compound to a compound represented by the following Formula (I): ##STR00001##
The ink composition for writing instruments is characterized by containing the coloring material described above.

Provided are an ink composition for writing instruments which has a good solubility of a coloring material in an ink solvent and which is less liable to cause bleeding and feathering on the written lines and is improved in a water resistance, and a coloring material used for preparing the above ink composition. The coloring material includes a material obtained by adding at least one selected from a leuco dye, a halochromic dye and a photochromic compound to a compound represented by the following Formula (I): ##STR00001##
The ink composition for writing instruments is characterized by containing the coloring material described above.

A lacquer composition is provided, comprising 20%-79.9% by weight, based on the total weight of the composition, of a thiol compound having two or more thiol groups, 20%-79.9% by weight, based on the total weight of the composition, of a compound having two or more carbon-carbon double bonds and 0.1%-10% by weight, based on the total weight of the composition, of a separating agent having an alkyl radical having 4-20 carbon atoms, where the alkyl radical is unsubstituted or fluorine-substituted and the alkyl radical is bonded to a functional group. Also provided are the use of this lacquer composition as a protective lacquer on an optical surface of an optical element in the production of the optical element, and an optical element comprising the protective lacquer.