Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Method of use – kit – or combined with marking instrument or...
Reexamination Certificate
1999-11-30
2001-12-04
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Method of use, kit, or combined with marking instrument or...
C503S202000, C503S209000, C503S212000
Reexamination Certificate
active
06326331
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to substantially light-insensitive black and white mainsheet thermographic recording materials with improved stability to direct sunlight.
BACKGROUND OF THE INVENTION
Thermal imaging or thermography is a recording process wherein images are generated by the use of thermal energy. In direct thermal thermography a visible image pattern is formed by image-wise heating of a recording material containing matter that by chemical or physical process changes colour or optical density. Most of the “direct” thermographic recording materials are of the chemical type. On heating to a certain conversion temperature, an irreversible chemical reaction takes place and a coloured image is produced.
BE-A 784,615 discloses a photographic material comprising a paper support, characterized in that the support is coated with a layer having a Sheffield smoothness between 5 and ca. 100, the layer containing a first binder of the type polysaccharide, a pigment, a second binder, a photosensitive compound, including 2,4-dihydroxy-benzophenone, and an oxidation-reduction imaging forming system.
EP-A 713 133 discloses a two sheet thermal imaging system consisting of (i) a donor element comprising on a support a donor layer containing a binder and a thermotransferable reducing agent capable of reducing a silver source to metallic silver and (ii) a receiving element comprising on a support a receiving layer comprising a silver source, capable of being reduced by means of heat in the presence of a reducing agent, a binder and a stabiliser selected from the group consisting of benzotriazoles, heterocyclic mercaptanes, sulphinic acids, 1,3,4-triazo-indinolines, 1,3-dinitroaryl compounds, 1,2,3-triazoles, phthalic acids and phthalic acid derivatives.
EP-A 809 142 discloses a recording material comprising a support, a thermosensitive element and a protective layer therefor, the thermosensitive element comprising a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith and a binder, wherein the thermosensitive element further comprises in reactive association with the substantially light-insensitive organic silver salt and the organic reducing agent a substituted, exclusive of groups having an exclusively electron withdrawing character, or unsubstituted compound with an unsaturated 5-membered heterocyclic ring annulated with an aromatic ring system, the ring consisting of nitrogen and carbon atoms with at least one of the nitrogen atoms having a hydrogen atom and none of the carbon atoms being directly linked to a sulfur atom or being part of a carbonyl-group.
Substantially light-insensitive black and white two sheet thermographic recording materials according to EP 713 133 produce an image in the receiving sheet with imagewise transferred reducing agent and hence totally different stability requirements to monosheet materials. Substantially light-insensitive black and white monosheet thermographic recording materials including non-N-substituted benzotriazoles according to the teaching of EP-A 809 142 exhibit poor stability to direct sunlight.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide a substantially light-insensitive black and white monosheet thermographic recording material based on organic silver salts and reducing agents with improved stability to direct sunlight and capable of producing an image with an acceptably neutral image tone.
Further objects and advantages of the invention will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
Surprisingly it has been found that incorporating non-chlorine-containing 2-(2′-hydroxyphenyl)benzotriazole derivatives and 2-hydroxy-benzophenone derivatives into substantially light-insensitive black and white monosheet thermographic recording materials based on organic silver salts and reducing agents results in materials whose prints exhibit improved stability to direct sunlight and an acceptably neutral image tone.
The above-mentioned objects are realized by a substantially light-insensitive black and white non-chlorine-containing stabilizer-containing monosheet thermographic recording material comprising a support and a thermosensitive element, said thermosensitive containing a substantially light-insensitive organic silver salt, a reducing agent therefor in thermal working relationship therewith and a binder, wherein the non-chlorine-containing stabilizer is selected from the group consisting of 2-(2′-hydroxyphenyl)-benzotriazole derivatives and 2-hydroxy-benzophenone derivatives.
A recording process is further provided according to the present invention comprising the steps of: (i) bringing an outermost layer of the above-mentioned thermographic recording material into proximity with a heat source; and (ii) applying heat from the heat source imagewise to the recording material while maintaining proximity to the heat source to produce an image; and (iii) removing the recording material from the heat source.
Use of a non-chlorine-containing stabilizer selected from the group consisting of 2-(2′-hydroxyphenyl)-benzotriazole derivatives and 2-hydroxy-benzophenone derivatives as a stabilizer against direct sunlight in a substantially light-insensitive black and white monosheet thermographic recording material comprising a support and a thermosensitive element, the thermosensitive element containing a substantially light-insensitive organic silver salt, a reducing agent therefor in thermal working relationship therewith and a binder, is also provided by the present invention.
Preferred embodiments of the invention are disclosed in the dependent claims.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment of the recording process, according to the present invention, the heat source is a thermal head with a thin film thermal head being particularly preferred.
DEFINITIONS
By substantially light-insensitive is meant not intentionally light sensitive.
By a non-chlorine-containing compound is meant a compound with no chlorine atoms in its structure.
By a polymer having active hydrogen atoms is meant a polymer having substituents with hydrogen atoms which readily react such as hydroxy groups, thiol groups, carboxy groups, -N-H groups, amino groups, amido groups etc.
By polyisocyanate is meant a compound having at least two isocyanate groups which may or no be blocked with groups which are readily displaced during a hardening process.
2-(2′-hydroxyphenyl)benzotriazole derivatives and 2-hydroxy-benzophenone derivatives
Preferred non-chlorine-containing 2-(2′-hydroxyphenyl)-benzotriazole derivatives have substituents on the benzene ring of the benzotriazole and/or the phenyl group for example alkyl groups, such as methyl, t-butyl, t-amyl, t-octyl etc., aryl, alkaryl, aralkyl, such as benzyl, &agr;,&agr;-dimethylbenzyl etc., alkoxy, alkcarboxylate groups etc. These groups may be further substituted with hydroxy, alkyl, alkaryl, aralkyl, aryl, alkoxy, alkcarboxylato, 2-benzotriazolo groups etc. Suitable non-chlorine-containing 2-(2′-hydroxyphenyl)-benzotriazole derivatives for use in the substantially light-insensitive black and white stabilizer-containing monosheet thermographic recording material of the present invention, while not adversely changing the neutrality of the image tone of the image background, are:
STAB 01: 2-(2′-hydroxy-5-methylphenyl)benzotriazole, TINUVIN™ P from CIBA-GEIGY;
STAB 02: 2-(2′-hydroxy-5′-t-octylphenyl)benzotriazole, CYASORB™ UV 5411 from American Cyanamid Co.;
STAB 03: 2-[2′-hydroxy-3′,5′-(di-t-butyl)phenyl]benzotriazole, TINUVIN™ 320 from CIBA-GEIGY:
STAB 04: 2-[2′-hydroxy-3′,5′-(di-t-amyl)phenyl]benzotriazole, TINUVIN™ 328 from CIBA-GEIGY:
STAB 05: 2-[2′-hydroxy-3′,5′-di-(&agr;,&agr;-dimethylbenzyl)phenyl]-benzotriazole, TINUVIN™ 900 from CIBA-GEIGY:
STAB 06: 2-[2′-hydroxy-5-(1″,1″,3&Pri
Horsten Bartholomeus Cyriel
Jansen Guy Denis
AGFA-GEVAERT
Hess Bruce H.
Leydig , Voit & Mayer, Ltd.
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