EP0119831A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Heat bleachable dye systems
Assignee: 3M Co
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Filing: 1984-03-14
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Granted: —
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Expires: 2004-03-14
Abstract
Abstract Photothermographic elements containing heat bleachable acutance/antihalation dyes and thermographic elements employing heat bleachable dyes of the formula: in which: nis2,3,4 or 5, at least one of R 1 to R 4 represent hydrogen and the remainder of R 1 to R 4 independently represent a hydrogen atom, an optionally substituted cycloalkyl group, an optionally substituted alkenyl group, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted heterocyclic aromatic group, or R 1 and R 2 together or R 3 and R 4 together represent the necessary atoms selected from C, N, 0 and S to complete a non-aromatic type ring, X ⊖ is an anion.
Inventors
- 👤 Gebran Jean Sabongi
- 👤 Bernard Alan Lea
- 👤 Stephen Sik Chiv Poon
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 04:21
CPC Classifications
G; G03; G03C; G03C1/00; G03C1/76; G03C1/825; G03C1/83; G03C1/832; G03C1/494; G03C1/498; G03C1/49836; G03C1/49845; G03C1/49854; Y; Y10; Y10S; Y10S428/00; Y10S428/913
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
184 words
A photothermographic element comprising a support having on one surface thereof one or more layers constituting an photothermographic medium, the element comprising an acutance/antihalation dye characterised in that said acutance/antihalation dye is a bleachable dye of the formula: in which: n is 2, 3, 4 or 5, at least one of R l to R 4 represent hydrogen and the remainder of R l to R 4 independently represent a hydrogen atom, an optionally substituted cycloalkyl group, an optionally substited alkenyl group, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted heterocyclic aromatic group, or R I and R 2 together or R 3 and R 4 together represent the necessary atoms selected from C, N, 0 and S to complete a non-aromatic type ring, X ⊖ is an anion, the free bonds of the polymethine chain being satisfied by hydrogen or any chain substituent of the type present in known cyanine dyes, said bleachable dye either being a) in reactive association with a mild reducing agent, or b) present in the element in an environment free from reducing agent.
Claim 2
Dependent Claim
184 words
A photothermographic element comprising a support having on one surface thereof one or more layers constituting an photothermographic medium, the element comprising an acutance/antihalation dye characterised in that said acutance/antihalation dye is a bleachable dye of the formula: in which: n is 2, 3, 4 or 5, at least one of R l to R 4 represent hydrogen and the remainder of R l to R 4 independently represent a hydrogen atom, an optionally substituted cycloalkyl group, an optionally substited alkenyl group, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted heterocyclic aromatic group, or R I and R 2 together or R 3 and R 4 together represent the necessary atoms selected from C, N, 0 and S to complete a non-aromatic type ring, X ⊖ is an anion, the free bonds of the polymethine chain being satisfied by hydrogen or any chain substituent of the type present in known cyanine dyes, said bleachable dye either being a) in reactive association with a mild reducing agent, or b) present in the element in an environment free from reducing agent.
Claim 3
Dependent Claim
107 words
An element as claimed in Claim 1, in which the element comprises a light-sensitive layer comprising silver halide, a silver salt of an organic fatty acid, a mild reducing agent and a toner layer, characterised in that the dye of formula (I) is incorporated: (i) in a layer on the side of the support opposite the light-sensitive layer provided said support is transparent, (ii) in a layer between the support and the light-sensitive layer, (iii) within the light sensitive layer, (iv) within the toner layer, or (v) in a separate layer over the toner layer, or (vi) over the light-sensitive layer if no toner layer is present.
Claim 4
Dependent Claim
35 words
$ An element as claimed in Claim 1 or Claim 2, characterised in that the dye of formula (I) is present in an amount to provide a transmissive optical density of from 0.05 to 0.8.
Claim 5
Dependent Claim
28 words
An element as claimed in Claim 3, characterised in that the dye is present in an amount to provide a transmissive optical density of from 0.1 to 0.4.
Claim 6
Dependent Claim
45 words
A thermographic element comprising a support bearing an imaging layer, characterised in that the imaging layer has as its major image forming component one or more dyes of the formula: in which R 1 to R 4 and n are as defined in Claim 1.
Claim 7
Dependent Claim
31 words
An element as claimed in Claim 5, characterised in that the dye of formula (I) is present in an amount to provide a transmissive optical density of from 0.5 to 1.5.
Claim 8
Dependent Claim
30 words
An element as claimed in Claim 5 or Claim 6, characterised in that the support is transparent and the element is suitable for use as a transparency for overhead projection.
Claim 9
Dependent Claim
18 words
An element as claimed in any preceding claim, characterised in that R 1 and R 3 are hydrogen.
Claim 10
Dependent Claim
18 words
An element as claimed in any preceding claim, characterised in that the polymethine chain is free from substituents.
Claim 11
Dependent Claim
34 words
An element as claimed in any preceding claim, characterised in that R 2 and/or R 4 is an optionally substituted aryl group containing up to 20 atoms selected from C, N, O and S.
Claim 12
Dependent Claim
47 words
An element as claimed in any preceding claim, characterised in that the dye of formula (I) is in reactive association with a mild organic reducing agent which is in a stoichiometric ratio relative to said dye or in an excess of up to 50 times this amount.
Claim 13
Dependent Claim
26 words
An element as claimed in Claim 11, characterised in that the mild reducing agent is selected from substituted phenols, hydroquinone, phenidone, phthalazinone, ascorbic acid and hydroxypyrimidine.
Claim 14
Dependent Claim
36 words
An element as claimed in any preceding claim, characterised in that the dye is in reactive association with a catalytic amount of a metal ion of Group II or Group III or a transition metal ion.
References Cited (Backward Citations)
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