Patent GB-1091291-A (GB)
Title: Method of forming a pressure-sensitive character-transfer sheet
IPC: B41M5/10
Filed: 1964-10-14
Abstract: Compositions used in making a pressure-sensitive character-transfer sheet (see Division D2) comprise (1) (a) a sensible component, (b) a polymeric binder and a plasticizer therefor, (c) a wetting agent, and (d) an inert organic solvent, in the form of a dispersion, and (2) (a) a dispersion of a vegetable wax and a mineral oil in a lower aliphatic alcohol, and (b) a solution of a rosin ester in a ketonic solvent, also in the form of a dispersion.  The two are heated so that they mingle to form a single layer.  The sensible material may be ferromagnetic, e.g. ferroso-ferric oxide, electrically conducting, e.g. aluminium powder, light-reflecting, light-absorbing, e.g. carbon black, luminescent, e.g. zinc sulphide, or radio-active, naturally or induced.  In the example, the first coating composition is made by ball-milling together ferroso-ferric oxide, ethylcellulose, coumarone-indene resin, mineral oil, an oil-soluble non-ionic surfactant and methyl ethyl ketone.  This is then applied to a foil of polyisoprene hydrochloride and dried at 40 DEG  C.  The second coating composition is made by fusing refined carnauba wax with mineral oil, dispersing it in ethyl alcohol and ball-milling the dispersion.  A diethylene glycol ester of hydrogenated rosin is dissolved in methyl ethyl ketone, and added to the wax dispersion. This composition was then applied over the first and heated to mingle the two.  Other materials referred to are: as binder, cellulose nitrate, cellulose acetate, methyl-cellulose, and polymers of vinyl acetate, vinyl chloride, vinyl alcohol or styrene, and as waxes: ouricury, montan, candelilla or mixtures of these.  The Specification also describes for purposes of comparison a sheet in which methyl alcohol is substituted for the ethyl alcohol of the example and the second coating dried by a blast of cold air.  The layers do not mingle, and the product is tacky and smudgy and gives poor copies.ALSO:A pressure-sensitive character-transfer sheet is made by (1) applying to a flexible polymeric base sheet a first coating of (a) a sensible component, (b) a polymeric binder and a plastcizer therefor, (c) a wetting agent and (d) an inert organic solvent, in the form of a dispersion, (2) drying the coating, (3) applying a second coating of (a) a dispersion of a vegetable wax and a mineral oil in a lower aliphatic alcohol, and (b) a solution of a rosin ester in a ketonic solvent, also in the form of a dispersion, and (4) warming so that the two coatings mingle to form a single layer.  The base sheet may be of polyisoprene hydrochloride, polyester, irradiated polyethylene or polypropylene.  The sensible material may be ferromagnetic, e.g. frroso-frric oxide, electrically conducting, e.g. aluminium powder, light-reflecting, light-absorbing, e.g. carbon black, luminescent, e.g. zinc sulphide, or radioactive, naturally or induced.  In the example, the first coating composition is made by ball-milling together ferroso-ferric oxide, ethylcellulose, coumarone-indene resin, mineral oil, an oil-soluble non-ionic surfactant and methyl ethyl ketone.  This is then applied to a foil of polyisoprene hydrochloride, and dried at 40 DEG C.  The second coating composition is made by fusing refined carnauba wax with mineral oil, dispersing it in ethyl alcohol and ball-milling the dispersion.  A diethylene glycol ester of hydrogenated resin is dissolved in methyl ethyl ketone, and added to the wax dispersion. This composition was then applied over the first and heated to mingle the two.  Other materials referred to are: as binder, cellulose nitrate, cellulose acetate, methyl-cellulose, and polymers of vinyl acetate, vinyl chloride, vinyl alcohol or styrene, and as waxes: ouricury, montan, candelilla or mixtures of these.  The Specification also describes for purposes of comparison a sheet in which methyl alcohol is substituted for the ethyl alcohol of the Example and the second coating dried by a blast of cold air.  The layers do not mingle, and the product is tacky and smudgy and gives poor copies.