Permanent or temporary writing on projection film - with opaque coating by incorporating appropriate solvent in pen

摘要

In a method for transcribing information manually or automatically onto a transparent support with an opaque coating which is to be projected, the writing point is fed with a liq. which renders the opaque coating transparent. Either (1) the liq. is a solvent for the coating; or (2) it is volatile, being pref. water, and not a solvent for the coating, evaporating in a fairly short time without alteration of the coating. The information disappearing after evapn. In the case of (1), the opaque coating can be: (a) an aq. dispersion of polystyrene or its copolymer deriv., the solvent being an organochlorine cpd., a ketone, an aromatic cpd. pr an ester; (b) an aq. dispersion of polyvinyl acetate with the solvent on aromatic cpd., a ketone, an ester, an organochlorine cpd., or an alcohol; (c) an aq. dispersion of polyethylene with an aromatic solvent; or (d) an acrylic resin, with the solvent an aromatic cpd., an ester a ketone, or an organochlorine cpd. No electric power source is need, nor coating after inscription. Writing can be carried out directly under supervision e.g. at a conference.