GB1573909A

GB1573909A - Photographic recording

Info

Publication number: GB1573909A
Application number: GB2145676A
Authority: GB
Original assignee: Agfa Gevaert NV; Agfa Gevaert AG
Current assignee: Agfa Gevaert NV; Agfa Gevaert AG
Priority date: 1976-05-24
Filing date: 1976-05-24
Publication date: 1980-08-28
Also published as: FR2353082A1; BE854193A; JPS52143815A; JPS6123543B2; CA1094859A; DE2719023A1; FR2353082B1

Description

(54) IMPROVEMENTS RELATING TO PHOTOGRAPHIC RECORDING (71) We, AGFA-GEVAERT, a Naamloze Vennootschap organised under the Laws of Belgium of Septestraat 27, B 2510 Mortsel, Belgium, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to photographic recording materials containing a photoreductant and a hydrogen-donating reductor precursor compound and to recording processes utilizing such material.

Recording systems based on the combined use of photoreductants and imaging agents are known e.g. from Research Disclosure No. 12617 -- October 1974.

The term photoreductant as used herein and in the claims hereof is hereby defined as a substance capable of hydrogen atom abstraction from a hydrogen donor on exposure to activating electromagnetic radiation.

Important classes of photoreductants are a-diketones, e.g. orthobenzoquinones, ortho-naphthoquinones and ortho-phenanthrenequinones; and anthraquinones.

United States Patent specification 3,926,637 describes a-diketones capable of such hydrogen abstraction and corresponding to the general formula

wherein each of R and R' represents an alkyl or branched chain-alkyl or a cyclic hydrocarbon group wherein the carbon atoms are part of an aromatic or cycloaliphatic ring, or R and R' together form part of an aromatic or cycloaliphatic ring, and x is either 1 or 2.

The said a-diketones are used for photoinduced hydrogen abstraction of a host polymer to effect cross-linking and a change in optical density of a recording medium containing said compounds.

Other examples of such photoreductants are bis-imidazolyl compounds capable of photoinduced hydrogen abstraction of compounds containing labile hydrogen. Photoreducible bis-imidazolyl compounds have been described in the United Kingdom parent specification 1,345,331 and corresponding to the general formula:

wherein each of R', R2 and R3 represents a carbocyclic or heterocyclic group with aromatic character, and each dotted line circle stands for 4 delocalized electrons.

Other substances capable of photoinduced hydrogen abstraction are photosensitive organic polyhalogen compounds e.g. corresponding to the general formula:

wherein: each of A, B, X and Y are chlorine. bromine or iodine, or wherein one of said substituents A, B, X or Y represents an alkyl group or a substituted alkyl group, an aryl group or a substituted aryl group, or an aroyl group, and the other substituents chlorine, bromine or iodine, or wherein at least two of said groups A, B, X or Y represent an aromatic acyl group and the other groups chlorine, bromine or iodine.

Preferred for its photosensitivity is carbon tetrabromide, which on exposure to ultra-violet radiation is decomposed as follows:

wherein the Br. radical acts as hydrogen abstractor.

Another reaction mechanism wherein CBr4 plays the role of photoexcited hydrogen abstractor is described by Fotland, The Journal of Photographic Science, Vol. 18 (1970) p. 37.

The hydrogen-donor may be a dye precursor compound such as diphenylamine that forms a blue triphenylmethane dye by reaction with photoradicals of CBr4 (see Photographic Science and Engineering Vol. 8, No. 2, March-April (1964) page 91-92).

The hydrogen donor may be a free radical polymerizable acrylic polyester as described in the aforementioned United States Patent specification 3,926,637, wherein the hydrogen abstraction results in a change of the optical properties of the polymer.

The hydrogen donor may likewise be a film-forming binding agent e.g.

polystyrene as described in Examples of United States Patent specification 3,846,131.

It is an object of the present invention to provide photographic recording materials containing hydrogen donor compounds that are particularly useful for recording systems based on photoinduced hydrogen abstraction, and more particularly to provide photographic recording materials containing hydrogen donor compounds that by hydrogen abstraction are converted into reducing agents operative in image formation through an oxidation-reduction process.

The present invention provides a photographic recording material containing on a support and in admixture with a binder, a photoreductant as hereinbefore defined, a reducible non-photosensitive metal-organic compound as hereinafter defined and a non-photosensitive hydrogen-donating compound from which hydrogen can be abstracted by the photoexposed photoreductant and which is a reductor precursor that corresponds to the general formula

wherein: each of R10 and R11 (which may be the same or different) represent hydrogen, an alkyl group, a monohydroxyalkyl group, a cycloalkyl group, an aryl group, or an alkoxycarbonyl group e.g. a

C2115-O-C- group, 0 A represents a single bond, an ethynylene group (CC3n or the group

wherein n represents a whole number, e.g. 1 or 2, and each of R12 and R'3 (which may be the same or different) represents hydrogen, or an alkyl group e.g. methyl, or together with the ethylene carbon atoms form a carbocyclic or heterocyclic ring.

Table 1 contains an illustrative list of reductor precursor compounds according to said general formula which compounds are particularly suitable for use according to the present invention.

TABLE 1

Boiling point (BP) No. of OC or melting compound R10 Z R" point (MP) OC 1 H - H BP 198 2 O ~ H MP 67 3 H,C- - H BP 189 4 H,C -CH BP 183 5 H -CEC- H MP 52-54 6 H H MP 112 7 HO(CH2)4- - H BP 178,'5 mm Hg 8 C2HOC- - C2H0O-C- BP 280 II II 0 0 The preparation of these compounds is known to those skilled in the art. Other suitable compounds according to the above general formula are described in Research Disclosure October 1973 Disclosure No. 11409 page 12.

The hydrogen abstraction of the reductor precursor compounds of the general formula proceeds by removal of the hydrogen atoms of the carbon atoms carrying the hydroxyl groups, so that enediol or ynediol compounds having strong reducing properties are formed.

In the manufacture of a recording material according to the present invention at least one reducible metal-organic compound and hydrogen-donating compound within the scope of said general formula is incorporated in a layer in admixture with a photoreductant. Said compounds are applied in a supported layer containing a binder that does not prevent chemical contact of said compounds.

Particularly suitable for forming the binder in recording materials according to the present invention is or are organic polymeric substance(s).

Illustrative thereof are cyanoethylated starches, celluloses, and amyloses having a degree of substitution of cyanoethylation of 2; polyvinyl-benzophenone, polyvinylidene chloride, polyethylene terephthalate e.g. obtained under the Trade Mark "MYLAR", cellulose esters and ethers such as cellulose acetate, cellulose propionate, cellulose butyrate, methylcellulose, ethylcellulose, hydroxypropylcellulose, polyvinylcarbazole, polyvinyl chloride, polyvinyl methyl ketone, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyacrylic and polymethacrylic alkyl esters such as polymethyl methacrylate and polyethyl methacrylate, copolymer of polyvinyl methyl ether and maleic anhydride, various grades of polyvinylformal resins such as so-called 12/85, 6/95 E, 15/95 S, 15/95 E and B-79, B-98. obtained under the Trade Mark FORMVAR. Of especial utility is polyvinylformal 15/95 E, which is a white, free-flowing powder having a molecular weight in the range of 24,000 - 40,000 and a formal content expressed as O,o polyvinylformal of approximately 82%, possessing high thermal stability, excellent mechanical durability, and resistance to such materials as aliphatic hydrocarbons, and mineral, animal and vegetable oils.

The image-wise formed reducing agent is colourless by nature and needs the reducible metal-organic compound to form a visible image, the said compound being defined as reducible metal-organic compound of the type that yields free metal by reduction in an oxidation-reduction reaction with the image-wise formed reducing agent.

According to an embodiment of the present invention a reducible organotellurium compound in which halogen e.g. chlorine is directly linked to a tellurium atom and in which an organic group of said compound contains at least one carbonyl group is used as imaging agent. Such compounds are within the scope of the following general formula: R-Te-Cl wherein: R represents an organic group, which by a carbon atom is linked to or by carbon atoms is ringclosed with the tellurium atom and which contains at least one carbonyl group, x and y are 1, 2 or 3, and x + y is 4 Said compounds as well as their preparation have been described in the UK Patent Specification 1,484,891.

A preferred class of imaging agents are organo-tellurium compounds corresponding to the following general formula: (Ar - CO - CH2)2TeCl2 wherein Ar stands for an aromatic group including a substituted aromatic group e.g. phenyl, methoxyphenyl, tolyl, or naphthyl. Bis(phenacyl) tellurium dichloride is a preferred imaging agent for use according to the present invention in combination with a photoreductant and at least one of said hydrogen-donating compounds.

In the imaging process described in said UK patent specification 1,484,891, the visible image is formed by tellurium metal separated from one of said organotellurium compounds by image-wise reduction. The reduction according to said UK patent specification proceeds with a so-called sensitizer, which actually is a photoreductant. Preferred photoreductants described herein and used in the present invention are aromatic diketones and especially 1,2- and 1,4benzoquinones with at least one fused-on carbocyclic aromatic ring.

Suitable photoreductants are listed in Table 2 together with their approximate spectral sensitivity range in nm.

TABLE 2 9, l0-phenanthrenequinone

U.V. Visible 1.1dibenzylfenocene 400 - 600 1-phenyl-1,2-propanedione 400 - 500 2-hydroxy- 1 *4-n aphtho quinone 400 - 500 benzil 400 - 450 furil 400 - 480 diacetylferrocene 400 - 450 acetylferrocene 400 - 450 1,4-bis(phenyl glyoxal)-benzene 400 - 500 o-naphthoquinone Up to 560 4,5-pyrinequinone Up to 530 4,5,9,10-pyrinequinone Up to 550 The following are illustrative photoreductants that are sensitive in the range up to about 400 nm and, therefore, are useful only in the ultraviolet range benzophenone, acetophenone, 1,5-diphenyl-1,3,5-pentanetrione, ninhydrin, 4,4'dibromobenzophenone, 2-t-butylanthraquinone and 1,8-dichloroanthraquinone.

The photoreductant is used in the recording material according to the present invention in an amount which is preferably at least equimolar with respect to the tellurium compound. The coverage of tellurium compound is preferably in the range of I to 10 g per sq.m.

The amount of hydrogen donating reductor precursor in the recording material is not critical. Pronounced improvements in sensitivity are obtained with amounts between 50 to 100 by weight with respect to the tellurium compound.

The present invention includes a recording method in which the above defined recording material is used. When containing as reducible metal-organic compound an organo-tellurium compound according to the above general formula the method includes the steps of information-wise exposing said material to activating electromagnetic radiation and overall heating to develop a tellurium metal image in the photoexposed parts of the material.

In the reduction of said organo-tellurium compounds aromatic diketones e.g.

9,1 0-phenanthrenequinone and 2-t-butylanthraquinone are especially satisfactory.

It is assumed that the following reaction scheme is followed in the production of tellurium metal images by means of 9,l()-phenanthrene-quinone (PQ) and bis(phenacyl)tellurium dichloride according to the following formula: (CH5COCH2)2TeCI2

By exposure with active electromagnetic radiation (h v) the phenanthrenequinone obtains excitation into the first singlet state ('PQ), which is converted by intersystem crossing to the triplet state (3PQ).

The phenanthrenequinone in its triplet state abstracts a hydrogen atom from a hydrogen donor (RH) and is transformed into the dihydrophenanthrenequinone (PQ.H2).

Dihydrophenanthrenequinone is a strong reducing agent, which sets free tellurium upon heating in contact with said organotellurium compound:

heat (C H5COCH2)2TeCI2 + 2 PQ.H2 > 2 PQ + 2 C8H5COCH3 + 2 HCI + Te From the preceding reaction scheme the advantageous use of a hydrogen donor, which itself becomes a reducing agent, is obvious. A compound R-R being itself a reductor is produced, which cooperates with the dihydrophenanthrenequinone in the reduction of the organotellurium compound.

This results in a substantial image intensification in the form of higher image densities.

The following reaction schemes illustrate the photoinduced hydrogen abstraction and formation of reducing agent for use according to the present invention.

The present invention is, however, not restricted to image-wise reduction of organo-tellurium compounds. Indeed, any recording material containing a photoreductant, said hydrogen-donating reductor precursor compound, and metalorganic compound that can be reduced by the reductor formed in the hydrogen abstraction from said hydrogen-donating compound, is within the scope of the present invention.

The recording material may further contain any photoreductant, which upon exposure to activating electromagnetic radiation becomes a hydrogen abstractor or yields hydrogen-abstracting radicals. Examples thereof and references thereof have been given in the prior art.

A dry photographic coating containing the above-mentioned ingredients can be formed by dissolving a binding agent or mixture of binding agents in a suitable inert solvent, which acts as dispersing or dissolving medium for the other ingredients and which is removed from the coating composition by evaporation so that a solid photographic recording layer on a properly chosen support is left. The supports may be of any kind encountered in silver halide photographic materials, e.g. paper and resin film.

The recording materials according to the present invention containing photoreductant, said hydrogen-donating reductor precursor compound, and a metal-organic compound e.g. tellurium-organic compound are suited for the production of visible images in a dry way by first image-wise exposing to activating electromagnetic radiation, to which the photoreductant is sensitive, followed by overall heating.

The heat-development generally lasts approximately 30 sec. to 300 sec.

depending on the temperature, which may vary from 80 to 2000 C.

The heat required to produce the metal image can be supplied in various ways.

So, the recording material can be developed by heat transport from hot bodies e.g.

plates or rollers or by contact with a warm gas stream e.g. hot air. Furthermore, the metal image can be developed by means of infrared radiation.

The following examples illustrate the present invention without, however limiting it thereto. All percentages or ratios are by weight, unless otherwise indicated.

Example 1.

77.7 g of VINYLITE VAGH (a Trade Mark) for a copolymer of vinyl chloride, vinyl acetate and vinyl alcohol (91/3/6) was dissolved in a mixture of 6 ml of methylene chloride containing 2% of silicone oil and 300 ml of methyl ethyl ketone.

9 g of bis(phenacyl) tellurium dichloride and 16.4 g of 2-t-butylanathraquinone in 300 ml of methylene chloride were added to the solution. The mixture obtained was divided in seven equal parts. To six parts thereof one of the compounds containing labile hydrogen listed in the following Table 3 was added in chemically equivalent amounts. The seventh part served as the blank.

Each composition was coated on a polyethylene terephthalate support in a ratio of 2 g of tellurium-organic compound per sq.m. The coatings were dried for 2 h at 30"C and subsequently for 20 h at 500C in a ventilated cabinet.

Each of the materials obtained was exposed for 100 s through a step wedge with constant 0.3 in the "SPEKTRAPROOF" (Trade Mark) exposure apparatus of Siegfried Theimer GmbH 6481 Obersatzbach, W.Germany equipped with a 2000 W lamp emitting with a maximum at abouat 350 nm.

The exposed materials were developed by heating at 1600C for 1 min.

The resulting maximum densities corresponding with the hydrogen donors, used are listed in Table 3.

TABLE 3

Added Maximum Hydrogen donor amount density 1. HO(CH2)3-OH 1.8 g 1.05 2. HOCH2--CH2OH 3.3 g 1.15 3. b 4.3 g 0.45 0 I' 4. toC\ 3.5 g 0.75 C/'N--CH20H II 0 5. -CHOH-CHH 3.3 3.3 g 2.15 6. H,C-CHOH-CH,OH 2.6 g 1.86 7. - - 0.30 The compounds 1, 3 and 4 are known hydrogen donors, which as appears from the results yield a substantially lower maximum density than the compounds according to the present general formula do.

Example 2.

38.8 g of VINYLITE VAGH were dissolved in a mixture of 3 ml of methylene chloride containing 2% of silicone oil and 150 ml of methyl ethyl ketone.

4.5 g of bis(phenacyl) tellurium dichloride and 8.2 g of t-butylanthraquinone in 300 ml of methylene chloride were added to the solution.

The resulting mixture was divided in three equal parts. To these parts one of the hydrogen donors listed in Table 4 was added in chemically equivalent amounts.

The processing of the samples was as described in Example 1.

TABLE 4

Hydrogen donor Amount added Maximum density 1. CONHCH2OH 5.2 g 0.46 7 -CH2OH 3.7 g 0.64 3. HoCH2-CH2OH 2.12 g 1.0 The compounds I and 2 are known hydrogen donors, which as appears from the results yield a substantially lower maximum density than the compound according to the present general formula does.

Example 3.

25.5 g of VINYLITE VAGH was dissolved in a mixture of 2 ml of methylene chloride containing 2% of silicone oil and 100 ml of methyl ethyl ketone.

3 g of bis(phenacyl)tellurium chloride and 4.8 g of t-butylanthraquinone in 100 ml of methylene chloride were added to the solution.

The mixture obtained was divided in two equal parts and to each part one hydrogen donor was added as indicated in Table 5 in chemically equivalent amounts. The further processing proceeded as described in Example 1.

TABLE 5

Hydrogen donor Added amount Maximum density 1. HOCH -C--C-CH2OH 2.9 g 0.50 CH3 CH3 I I 2. QH-C - C C -C-C,H, 5.8 g 0.11 I I OH OH Compound 1, which is within the scope of the present general formula yielded a higher maximum density than compound 2 does, from which no hydrogen atoms could be abstracted from the carbon atoms carrying the hydroxyl groups.

Example 4.

23 g of VINYLITE VAGH was dissolved in a mixture of 2 ml of methylene chloride containing 1% of silicone oil and 90 ml of methyl ethyl ketone. A solution of 4.5 g of bis(phenacyl tellurium dichloride and 8 g of t-butylanthraquinone dissolved in 90 ml dichloroethane were added to the mixture.

The mixture obtained was divided in three equal parts and to each part a hydrogen donor dissolved in a solvent as mentioned in Table 6 was added in chemically equivalent amounts. The further processing proceeded as described in Example 1.

TABLE 6

Maximum Hydrogen donor amount added density 1. Q- CH- CH20H 25 ml 3.8 gin 0.85 -I 25 ml of CH2Cl2 OH 2. C2HsOOC-CHCHCOOC2Hs 5.7 g in 0.90 I 1 40 ml of CH2C12 OH OH 3. CH,-CHOH-CHOH-CH, 2.5 g in 1.2 40 ml of CH2C12 WHAT WE CLAIM IS: 1. A photographic recording material containing on a support and in admixture with a binder, a photoreductant as hereinbefore defined, a reducible non-photosensitive metal-organic compound as hereinbefore defined and a nonphotosensitive hydrogen-donating compound from which hydrogen can be abstracted by the photoexposed photoreductant and which is a reductor precursor that corresponds to the general formula

wherein: each of R10 and R11 (which may be the same or different) represent hydrogen, an alkyl group, a monohydroxyalkyl group, an aryl group a cycloalkyl group or an alkoxycarbonyl group, Z represents a single bond, an ethynylene group or the group

wherein n represents a whole number, and each of R12 and R'3 (which may be the same or different) represents hydrogen, or an alkyl group, or together with the ethylene carbon atoms form a carbocyclic or heterocyclic ring.

2. A recording material according to Claim I, wherein the said photoreductant is an aromatic diketone.

3. A recording material according to Claim 2, wherein the aromatic diketone is 9,1 0-phenanthrenequinone or 2-t-butyl-anthraquinone.

4. A recording material according to any of Claims 1 to 3, wherein the reducible metal-organic compound is an organo-tellurium compound in which halogen is directly linked to a tellurium atom and in which an organic group of said compound contains at least one carbonyl group.

5. A recording material according to Claim 4, wherein the organo-tellurium compound corresponds to the following general formula: Rx - Te - Cly

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

TABLE 6

Maximum Hydrogen donor amount added density 1. Q- CH- CH20H 25 ml 3.8 gin 0.85 -I 25 ml of CH2Cl2 OH 2. C2HsOOC-CHCHCOOC2Hs 5.7 g in 0.90 I 1 40 ml of CH2C12 OH OH 3. CH,-CHOH-CHOH-CH, 2.5 g in 1.2 40 ml of CH2C12 WHAT WE CLAIM IS: 1. A photographic recording material containing on a support and in admixture with a binder, a photoreductant as hereinbefore defined, a reducible non-photosensitive metal-organic compound as hereinbefore defined and a nonphotosensitive hydrogen-donating compound from which hydrogen can be abstracted by the photoexposed photoreductant and which is a reductor precursor that corresponds to the general formula

wherein: each of R10 and R11 (which may be the same or different) represent hydrogen, an alkyl group, a monohydroxyalkyl group, an aryl group a cycloalkyl group or an alkoxycarbonyl group, Z represents a single bond, an ethynylene group or the group

wherein n represents a whole number, and each of R12 and R'3 (which may be the same or different) represents hydrogen, or an alkyl group, or together with the ethylene carbon atoms form a carbocyclic or heterocyclic ring.
2. A recording material according to Claim I, wherein the said photoreductant is an aromatic diketone.
3. A recording material according to Claim 2, wherein the aromatic diketone is 9,1 0-phenanthrenequinone or 2-t-butyl-anthraquinone.
4. A recording material according to any of Claims 1 to 3, wherein the reducible metal-organic compound is an organo-tellurium compound in which halogen is directly linked to a tellurium atom and in which an organic group of said compound contains at least one carbonyl group.
5. A recording material according to Claim 4, wherein the organo-tellurium compound corresponds to the following general formula: Rx - Te - Cly

wherein: R represents an organic group which by a carbon atom is linked to or by carbon atoms is ring closed with the tellurium atom and which contains at least one carbonyl group, x and y are 1, 2 or 3, and x + y is 4.
6. A recording material according to Claim 5, wherein the organo-tellurium compound corresponds to the following general formula: (Ar - CO - CH2)2TeCl2 wherein Ar stands for an aromatic group or a substituted aromatic group.
7. A recording material according to Claim 6, wherein the organo-tellurium compound is bis(phenacyl)tellurium dichloride.
8. A recording material according to any of the preceding claims, wherein the binder is formed of one or more polymers.
9. A recording material according to any of the preceding claims, wherein the reductor precursor is a compound of table 1 hereinbefore.
10. A recording material according to any of Claims 4 to 9, wherein the organo-tellurium compound is present in a layer at a coverage of 1 to 10 g per sq.m.
11. A recording material according to Claim 10, wherein the reductor precursor is present in an amount in the range 50% to 100% by weight based on the organo-tellurium compound.
12. A recording material according to Claim 10 or Claim 11, wherein the photoreductant is present in at least equimolar amounts with respect to the organotellurium compound.
13. A recording material according to Claim 1, substantially as described herein.
14. A recording process wherein a recording material according to any of the Claims 1 to 13, is information-wise exposed to electromagnetic radiation to which the photoreductant is sensitive and the exposed material is developed by overall heating to produce a metal image.
15. A recording process according to Claim 14, wherein the heating proceeds in the range of 80 to 2000 C.
16. A recording process according to Claim 14 and substantially as described herein.