Importance

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Abstract

In microcapsules of the type used for pressure-sensitive, carbonless copy papers, having walls formed from aliphatic diisocyanate and diamine and containing a solvent mixture with a dye precursor dissolved therein, the solvent mixture containing a component which easily dissolves the dye precursor and the capsule wall material and a component which only poorly dissolves the dye precursor and the capsule wall, the improvement comprising the poorly dissolving solvent component is an alkylbenzene having from 8 up to 14 C-atoms in the alkyl moiety; and the easily dissolving solvent component is selected from the group consisting of diisopropyl naphthalene, a hydrogenated terphenyl, an alkylated diphenyl, a diphenyl alkane, a chloroparaffin and a mixture thereof, the ratio of easily to poorly dissolving components ranging form 15:85 to 75:25 vol %, and being adjusted within this range so that a solution of the wall-forming aliphatic diisocyanate is just at the turbidity point in the mixture of easily dissolving and poorly dissolving components.

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First Claim