Coating processes – Transfer or copy sheet making – Reactive components
Patent
1981-02-11
1983-07-19
Morgenstern, Norman
Coating processes
Transfer or copy sheet making
Reactive components
427386, 428913, B41M 312
Patent
active
043944078
DESCRIPTION:
BRIEF SUMMARY
In the DE-AS No. 1181245 there is described a multi-layered copy paper, which consists at least of one carrier layer of paper, a ray-absorbing layer, and a thermochrome layer. The thermochrome layer contains a thermoplastic substance, for example ethylcellulose, as a film-forming means together with a mixture of a heavy metal salt wih butylphyrocatechin, or a water soluble heavy metal salt with thiourea. The copy paper is intended for contactless thermography with the aid of a source of rays, whereby the ray-absorbing layer permits a reduction of the radiated energy. However, the thermochrome layer of this kind will not readily adhere to non-porous, non-absorbant smooth surfaces and could become detached from the carrier layer or otherwise damaged or contaminated if heat was transferred thereto by means of a pressure head. Consequently, the possibilities of use of this thermochrome layer are very limited indeed.
It is a task of the present invention to devise a method for the manufacture of a thermochrome layer containing a metallic compound and an organic sulfur compound reactable with this metallic compound and acquiring a permanent dark discoloration upon exposure to heat, as well as a synthetic plastic material as a layer-forming material, which is also suitable to cover non-porous, non-absorbent smooth surfaces. It is a further task to create optical contrasts by contactless thermal transmission by means of a heating head without any contamination or damage occurring on these thermochrome layers manufactured from this lacquer. The ingredients suitable for their manufacture should, if necessary, have a long-term stability prior to processing, and the thermochrome layers manufactured therefrom should harden on their own at room temperature. Finally these layers should have particular properties which enable them to be applied to new uses.
The main task is solved in that the metallic compound includes a selected heavy metal or noble metal, and in that two components are used for the layer-forming material, these components forming a transparent synthetic plastic material which is stable when heated and which is compatible with the metallic compound, the sulfur compound and the reaction product thereof which is capable of acquiring the permanent dark discoloration.
For the manufacture of such thermochrome lacquers and layers manufactured therefrom, it has been shown suitable, if at least two ingredients, which have a long-term stability of their own are used, and which consist of mixtures, which contain a contrast-forming component, and a layer-forming means compatible therewith. The first ingredient may, for example, consist of a heavy metal compound, or a noble metal compound finely dispersed in a resin base, and the second ingredient may consist of a sulfur/carbon-covalent compound finely distributed and dispersed in a hardener for the resin base, setting free sulfur in ionized form, when heated beyond 70.degree. C. Where only a small percentage of a hardener can be used, the sulfur/carbon-covalent compound may also be separately dispersed in a resin base, and the hardener may be used as a third ingredient which is stable per se.
The resin base may contain a prepolymerizate of a methacrylic acid dissolved in aromatic solution means, or a compound containing epoxy groups, and slowly hardening into epoxy resin, by way of a moderate exothermal reaction, whereby in the first case a diol, and in the second case a compound containing amine groups is used as a hardener.
The heavy metal compound, or the noble metal compound, should be an oxide not soluble in water or solutions, a salt, or a compound with an inorganic anion, or a compound with a monocarboxylic acid with 2, 8, 10, 12, 14, 16, 18, 20, 22 or 28 C-atoms, or a compound with a dicarboxylic acid, such as fumaric acid, or an adipic acid of the metals bismuth, copper, silver, gold, mercury, thallium, lead, vanadium, molybdenum, tungsten, rhenium, iron, cobalt, nickel, palladium, or platinum. As a sulfur/carbon-covalent compound a compound of the general
REFERENCES:
patent: 3178306 (1965-04-01), Wark
Bell Janyce A.
LGZ Landis & Gyr Zug AG
Marmorek Ernest F.
Morgenstern Norman
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