Encapsulated water paper

Claim 1

In a paper sheet adapted for the electrostatographic reproduction of images on both sides thereof by the deposition on its surface of toner particles in imagewise configuration and fusing the toner into the sheet by the application of heat and pressure thereto, the improvement which comprises a surface size on one or both sides of said sheet, said surface size comprising a binder material and a plurality of microcapsules which comprise a core of water or hydrated salt encased in an impervious capsule wall of a solid material capable of being ruptured by the heat and pressure applied to the sheet during the fusing of the image formed on the first side thereof and in the situation where a hydrated salt is employed as the microcapsule core the salt is selected from those hydrates which give up their water of hydration at a temperature equal to or below that to which the paper is subjected during the fusing operation, said microcapsules being present in an amount which will release sufficient water into the paper sheet so as to provide about two percent water by weight of the paper sheet after the fusing of the image formed on the first side thereof.