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
2001-11-28
2004-02-03
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...
C427S150000, C427S152000, C503S212000
Reexamination Certificate
active
06686313
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to thermographic recording materials whose prints have improved archival properties.
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.
JN 07-248 567 discloses a thermosensitive recording material having a thermosensitive recording layer containing at least: a) an organic silver salt; b) a reducing agent; c) a water-soluble binder; d) a development accelerator such as phthalazinones; and e) a hardening agent for c). Included in a list of hardening agents as particularly preferred were the compounds 1,3,5-triacryloyl-hexahydro-s-triazine and 1,2-bis vinylsulfonylmethane, 1,3-bis(vinylsulfonylmethyl)propanal-2, bis(&agr;-vinyl sulfonyl acetoamido)ethane, 2,4-dichloro-6-hydroxy-s-triazine/sodium salt, 2,4,6-triethylene imino-s-triazine, boric acid etc., the added amount being preferably 0.5-5 wt % with respect to the water-soluble binder. However, only bis(&agr;-vinyl sulfonyl acetoamido)ethane, CH
2
═CH—SO
2
—CH
2
—CONHCH
2
—CH
2
—NH—COCH
2
—SO
2
—CH═CH
2
, was an ingredient in the thermosensitive recording layers of the examples, it being present in the thermosensitive recording layer of example 1 together with the reducing agents bisphenol B and propyl gallate, gelatin and silver behenate.
In printing with thermographic materials for medical applications for viewing with a light box, optimum diagnosis requires a blue-black image tone so that the higher ability of the human eye to distinguish detail with such image tone can be exploited, thereby improving the diagnostic value of such prints. Such image tone should be independent of the shelf life of the thermographic recording material prior to printing and also of archival time after printing. Image tone can be assessed on the basis of the L*, a* and b* CIELAB-values as determined by spectrophotometric measurements according to ASTM Norm E179-90 in a R(45/0) geometry with evaluation according to ASTM Norm E308-90. The mechanical stresses which thermographic recording materials undergo during the thermal printing process require the use of hardened polymers and hence of hardening agents to harden the polymers. However, such hardening agents not only harden the polymer, but can also have a prohibitive effect on image tone, which is undesirable. There is therefore a need for hardening agents and polymer-hardening agent systems for hardening thermographic recording materials, which have substantially no effect on the image tone of prints produced with such hardened thermographic recording materials.
It is therefore an object of the present invention to provide a hardener for substantially light-insensitive black and white thermographic recording materials containing an organic silver salt, a reducing agent therefor in thermal working relationship therewith and an amino-group-containing polymer, which produces adequate hardening of the amino-group-containing polymer, while not substantially affecting the image tone or image tone stability of thermographic prints produced therewith.
Further objects and advantages of the invention will become apparent from the description hereinafter.
BRIEF SUMMARY OF THE INVENTION
Since divinylsulfone compounds are well-known hardeners for amino-group-containing polymers, it would be expected that all divinylsulfone compounds would be equally effective as hardeners of amino-group-containing polymers in substantially light-insensitive thermographic recording materials, see JN 07-248 567. However, it has been surprisingly found that only substantially light-insensitive thermographic recording materials comprising amino-group-containing polymers hardened with particular divinylsulfone compounds are capable of providing prints whose image tone is substantially unaffected by the divinylsulfone compound used, whereas prints produced with thermographic recording materials hardened with other divinylsulfone compounds exhibit image tones which have been substantially affected by the divinylsulfone compound used.
The above mentioned objects are realized by providing a monosheet black and white substantially light-insensitive thermographic recording material comprising a thermosensitive element and a support, the thermosensitive element containing a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith and a binder, wherein the thermographic recording material comprises a reaction product of an amino-group containing polymer and a compound according to formula (I):
wherein each of R
1
, R
2
, R
3
and R
4
is independently hydrogen or an optionally substituted alkyl, aryl, heteroaryl, alkoxy or aryloxy group; L is a divalent linking group selected from the group consisting of oxygen and optionally substituted alkyl, aryl, heteroaryl, alkenyl and alkynyl groups; and m is either 0 or 1; and n is either 0 or 1.
A process is also provided by the present invention for coating a support with the above-described thermosensitive element comprising the steps of: applying a solution or dispersion containing the compound according to formula (I) to a support; and reacting the compound according to formula (I) with an amino-group-containing polymer, the compound according to formula (I) and the amino-group-containing polymer being either in the same layer or in immediately adjacent layers.
Use is also provided by the present invention of a compound according to formula (I):
wherein each of R
1
, R
2
, R
3
and R
4
is independently hydrogen or an optionally substituted alkyl, aryl, heteroaryl, alkoxy or aryloxy group; L is a divalent linking group selected from the group consisting of oxygen and optionally substituted alkyl, aryl, heteroaryl, alkenyl and alkynyl groups; and m is either 0 or 1; and n is either 0 or 1, in the preparation of thermographic recording materials containing a substantially light-insensitive organic silver salt.
A thermographic imaging process comprising the steps of: providing the above-described monosheet black and white substantially light-insensitive thermographic recording material; and image-wise applying heat to said thermographic recording material under substantially water-free conditions.
Preferred embodiments are disclosed in the dependent claims.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment of the thermographic recording process, according to the present invention, the heat source is a thermal head with a thin film thermal head being particularly preferred.
The term alkyl means all variants possible for each number of carbon atoms in the alkyl group i.e. for three carbon atoms: n-propyl and isopropyl; for four carbon atoms: n-butyl, isobutyl and tertiary-butyl; for five carbon atoms: n-pentyl, 1,1-dimethyl-propyl, 2,2-dimethylpropyl and 2-methyl-butyl etc.
By substantially light-insensitive is meant not intentionally light sensitive.
The term thermographic recording material includes substantially light-insensitive thermographic recording materials and photothermographic recording materials in which a photosensitizing material such as photosensitive silver halide is present in the thermosensitive element.
Heating in a substantially water-free condition as used herein, means heating at a temperature of 80 to 250° C. The term “substantially water-free condition” means that the reaction system is approximately in equilibrium with water in the air, and water for inducing or promoting the reaction is not particularly or positively supplied from the exterior to the element. Such a condition is described in T. H. James, “The Theory of the Photographic Process”, Fourth Edition, Macmillan 1977, page 374.
Compounds according to formula (I):
are used in the thermoplastic recording materials of the present invention, wherein each of R
1
, R
2
, R
3
and R
4
is independently hydrogen or an optionally substituted alkyl, aryl, heteroaryl, al
De Keyzer Rene
Hoogmartens Ivan
Loccufier Johan
Uyttendaele Carlo
Agfa-Gevaert
Hess Bruce H.
Leydig , Voit & Mayer, Ltd.
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