JPH09138506A - Image formation material and manufacture of planographic printing plate by silver salt diffusion transfer processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve planographic characteristics of a planographic printing plate based on DTR method. SOLUTION: This image forming material is used to produce a planographic printing plate by silver salt diffusion transfer treatment. The image forming material has a silver halide emulsion layer and an image accepting layer on a base body. The image accepting layer contains physical developing nuclei, inorg. colloidal material and single polymer or copolymer of acrylamide or methacrylamide.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to an image forming material for producing a lithographic printing plate by a silver salt diffusion transfer method and a method for producing a lithographic printing plate using the same.

BACKGROUND OF THE INVENTION The principle of the silver complex salt diffusion transfer reversal method (hereinafter referred to as the DTR method) is described in, for example, US Pat. No. 2352014 and The Focal Press in London and New York, 1972, An.
Photographic Silv by dre Rott and Edith Weyde
er Halide Diffusion Processes book.

In the DTR method, the undeveloped silver halide of a photographic silver halide emulsion layer material that has been exposed according to information is converted into a soluble silver complex compound with a so-called silver halide solvent, which is diffused into an image receiving material. In which, in the presence of physical development nuclei, is reduced with a developing agent to form a silver image (DTR image) having an image density value inverted from the black silver image obtained in the exposed area of the photographic material it can.

A DTR image bearing material has a DTR silver image area,
It can be used as a lithographic printing plate to form water repellent ink receptive areas on a water receptive ink repellent background. The DTR image is placed in an image receiving layer of a sheet or web material that is another material to the photographic silver halide emulsion material (a so-called two-sheet DT).
R materials) so-called single support materials (also referred to as monosheet materials) which can be formed or contain at least one photographic silver halide emulsion layer integrally with an image-receiving layer in water-permeable relationship therewith In the image receiving layer. D
The latter mono-sheet type is preferred for the production of offset printing plates by the TR method. For example, GB 1 246 661 consists of a sheet material comprising an outer hydrophilic colloid layer on the side where the silver image coming from the underlying exposed silver halide layer is enriched by the silver complex diffusion transfer reversal method. A method for producing a lithographic printing plate is described. The silver image formed on the surface is suitable for printing an image by a lithographic printing method using a wetting liquid.

[0005] Commercially available lithographic printing plate precursors of the latter type typically comprise on a flexible support such as polyester or paper, a base layer acting as an antihalation layer, a silver halide emulsion layer, and A surface layer containing physical development nuclei on which a silver image is formed is contained in this order.

Alternatively, a lithographic printing plate prepared by a silver salt diffusion transfer treatment is prepared by forming a receptor layer containing physical development nuclei and a silver halide emulsion layer on a hydrophilic support such as an aluminum support (for example, see EP-A410500). It can be obtained by providing in order. Following exposure and development,
The plate is washed with water or an aqueous liquid to remove the silver halide emulsion layer and any other layers above the receiving layer, exposing the silver image formed in the receiving layer.

The lithographic printing plate precursor (also referred to as an image forming material) described above can be exposed by a camera.
Or they can be exposed by scanning exposure, for example laser or LED exposure. The latter offers the advantage that the production of the printing plate is simplified by the fact that the paste-up to be used for the exposure of the imaging element can be completely made on a computer. This paste-up made on this computer is then
It is transferred to an image setter, for example equipped with a laser, which undertakes exposure of the imaging material, for example.

Lithographic printing plates obtained by the silver salt diffusion transfer method, and particularly those having a flexible support, generally use a photosensitive polymer composition or a diazo composition as a photosensitive coating for making a printing plate. The printing durability is limited as compared with the aluminum-based printing plate. Nevertheless, lithographic printing plates based on flexible supports offer the advantage that they are less expensive than printing plates based on aluminum supports. DTR plates with an aluminum support offer the advantage of high sensitivity over a large spectral range.

Accordingly, there is a continuing need to improve the printing durability of silver salt diffusion transfer plates. A possible improvement in print durability is preferably not an increase in the number of copies that must be discarded at the start of the printing process, for example as a result of poor ink acceptance or ink acceptance in non-image areas.

EP-A 546598 teaches the use of physical development nuclei having an average diameter of less than 6 nm in order to reduce the ink receptivity in the non-printed areas, in which case
The relative number of nuclei having a diameter greater than 4.5 nm is less than 15% of the total number of nuclei in the image receiving layer.

US Pat. No. 4,160,670 describes specific hydrophilic copolymers for improving the ink repellency of background areas. Among the numerous copolymers mentioned, mention is made of acrylamides and copolymers of comonomers having an affinity for physical development nuclei, for example pyridine and vinylimidazole.

In US Pat. No. 5,236,802, the presence of polyacrylamide or a copolymer of acrylamide in the physical development nuclei layer or adjacent layers improves ink receptivity in the image areas and further improves ink repellency in the background areas. It describes that you do.

US Pat. No. 2,698,237 describes a DTR image receiving material which comprises an image receiving layer having metal sulfide nuclei precipitated in an aqueous silicon dioxide dispersion. The nucleus is taught to exhibit high activity. Further, a hydrophilic organic polymer binder in a layer containing physical development nuclei of a monosheet DTR material suitable for producing a lithographic printing plate is, for example, U
S-P3728114; 4160670; 460696
5; 4510228; 4743525; 487919
3: 5153097; 51008871 and 504135
4.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the lithographic performance of lithographic printing plates based on DTR, in particular the ink receptivity of the printing areas, the ink repellency of the background (reducing stain and toning) and printing. It is to improve properties such as durability.

Other objects of the invention will be apparent from the following description.

According to the present invention, there is provided an image forming material for making a lithographic printing plate by a silver salt diffusion transfer treatment, the image forming material containing a silver halide emulsion layer and a receiving layer on a support, The receptive layer contains (i) physical development nuclei, (ii) an inorganic colloidal substance, and (iii) a hydrophilic polymer which is a homopolymer or copolymer of acrylamide or methacrylamide.

According to the present invention, an image-forming material as described above is image-wise exposed, and the image-forming material thus obtained is image-wise exposed to a developing agent and a silver halide solvent using an alkaline processing liquid. Also provided is a method of making a lithographic printing plate by developing in the presence.

DETAILED DESCRIPTION OF THE INVENTION The combined use of a colloidal inorganic material and a hydrophilic polymer according to the present invention improves not only the ink receptivity of the printed areas but also the ink repellency of the background and yet obtains high printing durability. The term hydrophilic polymer in the context of the present invention means that the particular polymer is soluble in water or an aqueous solution to the extent that it allows coating of the polymer in an amount of at least 0.05 mg / m ^2. Used to indicate.

Suitable inorganic colloidal materials for use in the present invention are, for example, colloidal silica or colloidal hydrous aluminum silicate. Particularly preferred in the present invention is colloidal clay.

The clay is essentially a hydrous aluminum silicate in which an alkali metal or alkaline earth metal is present as the main constituent. Also, in some clay minerals, magnesium or iron or both replace all or part of the aluminum. The final chemical constituents of clay minerals vary not only in amount but also in the way they are combined or present in various clay minerals. Natural clays are well known, but synthetic clays can also be made in the lab, allowing a great deal of freedom to provide tailor-made and reproducible clay products for use in different applications.

From natural clays, smectite clays including laponite, hectorite and bentonite are well known and can be used in the present invention. For smectite clay, some substitution may occur in both the octahedral and tetrahedral layers of the crystal lattice, resulting in a small number of interlayer cations. Smectite clays absorb water and organic liquids between the composite layers and form a group of "swellable" clays with significant cation exchange capacity. Synthetic and chemically pure clays have been produced from these smectite clays.
They are particularly suitable for use in the present invention.

The clay used according to the invention is preferably smectic clay, more preferably synthetic smectic clay, most preferably synthetic laponite. Preferred synthetic laponite clays for the present invention include, for example, those of London.
LAPONITE, a trademark product of LAPORTE INDUSTRIES Limited
There are RD, LAPONITE RDS and LAPONITE JS.

Synthetic clay and its manufacturing process are described in EP Patent 16
1411B1.

LAPONITE JS was announced as a synthetic layered hydrous magnesium magnesium fluorosilicate incorporating an inorganic polyphosphate peptizer. LAPONITE RD is
It was announced as a synthetic layered hydrous sodium lithium magnesium silicate mixed with an inorganic polyphosphate peptizer. LAPONITE RDS was announced as a synthetic layered hydrous sodium lithium magnesium silicate mixed with an inorganic polyphosphate peptizer. The silicate is a good free hydrate in water and a free flowing white powder to give a clear and colorless colloidal dispersion (also called sol) of ultimately low viscosity.

The inorganic colloidal material according to the present invention can be used in various amounts. However, when the inorganic colloidal substance is 0.
^{1mg / m 2 ~20mg / m 2} , more preferably 0.5
It is most efficient when used in amounts of ^{mg / m 2 ~10mg / m 2} .

The inorganic colloidal material according to the invention may be present during the production of the physical development nuclei, in which the nuclei are precipitated on the inorganic colloidal material, especially when the inorganic colloidal material is a clay such as laponite. be able to. On the other hand, the inorganic colloidal substance can be added to the coating solution of physical development nuclei after the production of physical development nuclei. In the latter case, the inorganic colloidal material and physical development nuclei will be present as discrete particles dispersed in the hydrophilic polymer.

According to a very preferred embodiment in the context of the present invention, the hydrophilic polymer is polyacrylamide or polymethacrylamide. However, copolymers of (meth) acrylamide can also be used according to the invention. Copolymer types of particular interest are those in which at least one of the comonomers has a heterocyclic ring system having at least N, O or S atoms. Specific examples of heterocyclic rings include imidazole, imidazoline, pyrazole, thiazolidine, thiazolidone, thiazolone, indazole, pyridine, triazine, benzotriazole, tetrazole and the like. Specific examples of comonomers having a heterocyclic group include, for example, vinyl pyridine, vinyl imidazole, vinyl imidazoline, vinyl piperidine, vinyl quinoline and the like.

The comonomers are preferably present in the structural units of the polymeric binder, which are preferably present in an amount of 0.1 to 20 mol% of the polymer, preferably 0.5 to 5 mol%. . Other comonomers which can be used in combination with the (meth) acrylamide and optionally the above-mentioned comonomers include, for example, vinyl monomers such as vinyl acetate, vinyl butyral, vinyl chloride, vinylidene chloride, vinyl (meth). ) Acrylic acid and its esters, styrene and derivatives, such as sulfonic acid or carboxylic acid substituted styrene, vinyl ether, vinylphosphonic acid, maleic acid and derivatives. The copolymer according to the present invention can be a random copolymer, an alternating copolymer or a block copolymer.

The degree of polymerization (number average) of the polymer used according to the present invention is preferably 20 to 1000. The average degree of polymerization according to the invention is measured by means of GPC, in this case 0.05 mol of sodium chloride in water / eluent /
1 solution was used with TSK column 3000PW and polyethylene glycol as reference. A degree of polymerization that is too low will cause dissolution of the polymer from the printing plate during processing, while a degree of polymerization that is too high will provide coating difficulties.

The hydrophilic (meth) acrylamide (co) polymers are preferably used in combination with other hydrophilic polymers such as polyvinyl alcohol and / or poly (meth) acrylic acid. (Meth) acrylamide (co) in the receptor layer
The total amount of the polymer and the optional additional polymer is 0.05 mg / m ²
It is preferably ˜1.5 g / m ² .

The hydrophilic polymers used according to the invention can be added to the coating solution of the receiving layer after the production of the physical development nuclei, or they can be present during the production of the physical development nuclei. The latter is particularly preferred in the case of comonomers with heterocyclic groups and copolymers of (meth) acrylamide. The (meth) acrylamide homopolymer is preferably added to the coating solution after the physical development nuclei have been prepared.

Physical development nuclei suitable for use in accordance with the present invention include those commonly used in the DTR process such as noble metals such as silver, palladium, gold, platinum, sulfides of heavy metals, selenides or tellurides such as PdS, Ag ₂
S, AgNiS, CoS, etc. Preferably PdS,
Ag ₂ S or AgNiS nuclei are used.

The physical development nuclei according to the present invention can be produced by known methods. For example, the noble metal nucleus is US-P43048.
35. Heavy metal sulfides can be prepared by adding an aqueous solution of heavy metal ions to a solution containing sulfur ions. The resulting nuclei are preferably stabilized by imparting a charge thereon and / or by using a stabilizer such as an absorbing polymer on the surface of the developing nuclei. Other suitable stabilizers are large organic molecules that readily absorb on the surface of the nucleus.
Examples are water-solubilizing groups such as --COOH, --SO ₃ H or-
There are heterocyclic compounds containing SO ₂ H, for example tetrazole containing water solubilizing groups as described in European patent application 218752. The amount of nuclei used in the image receiving layer is preferably 0.02 mg / m ^{2 to} 10 mg / m ² .

Preferably, the physical development nuclei have an average diameter of less than 6 nm and the number of nuclei having a diameter of greater than 4.5 nm is less than 15% of the total number of nuclei. Although the size of the nucleus is indicated by the diameter, this does not necessarily mean that the nucleus is spherical. By diameter is meant the diameter of a sphere having the same volume so that different sizes of nucleus sizes can be characterized with the same parameters.

According to a highly preferred embodiment in the context of the present invention, the imaging element comprises on a support a silver halide emulsion layer and a receiving layer according to the invention as described above in this order.

Photographic silver halide emulsions are, for example, of Parry's.
Paul Montel 1967, P. Glafkides, Chimi
e et Physique Photographique; The F in London
ocal Press 1966, GF Duffin, Photo
graphic Emulsion Chemistry; and The London
It can be prepared from soluble silver salts and soluble halides by different methods as described in Making and Coating Photographic Emulsion by Focal Press, 1966, VL Zelikman et al.

The photographic silver halide emulsions used in accordance with the present invention can be prepared by mixing the halide and silver solutions under conditions which are partially or completely controlled by temperature, concentration, order of addition and rate of addition. . Silver halide can be precipitated by the single jet method or the double jet method.

The silver halide grains of the photographic emulsions used according to the invention can have a regular crystalline form such as cubic or octahedral, or they can have a transition form. They can also have disordered crystalline forms such as spherical or tabular, or they can have complex crystalline forms containing a mixture of said ordered and disordered crystalline forms.

According to the invention, the emulsion preferably consists mainly of silver chloride, preferably at least 7 silver chloride.
0 mol%, more preferably at least 80 mol%, most preferably at least 95 mol%. If present, the remainder of the silver halide can be silver bromide, optionally silver iodide in an amount up to 3 mol%, preferably up to 1.5 mol%. According to a particularly preferred embodiment in the context of the present invention, 2 mol%
A silver chloroiodide emulsion having the following silver iodide is used. Silver chloroiodide emulsions first precipitate silver nitrate with a water-soluble chloride, such as sodium chloride, and then at the end of the precipitation, typically during the last 10% of the water-soluble iodide, such as potassium iodide. It can be conveniently prepared by precipitation, thus yielding silver halide grains having silver iodide in the shell of the silver halide grains.

The average grain size of the silver halide grains is 0.10.
０．７0.70 μm, preferably 0.25 to 0.45 μm.

The size distribution of the silver halide grains of the photographic emulsion to be used according to the present invention can be homodisperse or heterodisperse. A homodisperse size distribution is obtained when 95% of the particles have a size that does not deviate more than 30% from the average size.

Preferably during the precipitation stage iridium and / or rhodium containing compounds or a mixture of both are added.
The concentration of these added compounds, AgNO ₃ 1 10 ^-8 to 10 ^-3 mole for mole, preferably AgNO ₃
The range is from 10 ^-7 to 10 ^-6 mole per mole. This means that a small amount of iridium and / or
Or the incorporation of rhodium, so-called iridium and / or rhodium dopants. As is known to those skilled in the art, many scientific and patent literatures describe the addition of iridium or rhodium containing compounds or compounds containing other elements of Group VIII of the Periodic Table during emulsion preparation.

The emulsion can be chemically sensitized by adding sulfur containing compounds such as allyl isothiocyanate, allyl thiourea, and sodium thiosulfate during the chemical ripening step. A reducing agent such as BE-P493634;
And the derivatives of polyamines such as diethylenetriamine or aminomethanesulfonic acid can also be used as chemical sensitizers. Other suitable chemical sensitizers include noble metals and noble metal compounds such as gold, platinum, palladium, iridium, ruthenium and rhodium. This chemical sensitization method is based on Z. Wiss. Photogr. Ph.
otophys. Photochem. (1951), 46, 65-7
It is described in R. KOSLOWSKY's paper on page 2.

Emulsions of DTR material can be spectrally sensitized according to the spectral emission of the exposure source for which the DTR material is designed.

A suitable sensitization fee for the visible spectrum band is John Wiley & Sons, published in 1964 by The
FM in Cyanine Dyes and Related Compounds
Includes methine dyes such as those described by Hamer. Dyes that can be used for this include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, isopolar cyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes. Particularly useful dyes are those belonging to the cyanine dyes, merocyanine dyes and complex merocyanine dyes.

Silver halide emulsions are conventional stabilizers, for example equipolar or salt compounds of mercury with aromatic or heterocyclic rings such as mercaptotriazole, simple mercury salts,
Can contain sulfonium mercury double salts and other mercury compounds. Other suitable stabilizers are azaindenes, preferably tetra or pentaazaindenes, especially those substituted with hydroxy or amino groups. Compounds of this type are described in Z. Wiss. Photogr. Photophys. Photochem.
Published in two years, 47, p. 2-27 by BIRR. Other suitable stabilizers include heterocyclic mercapto compounds, for example heterocycles substituted with bulky substituents such as alkyl groups having at least 5 carbon atoms or aryl groups having at least 8 carbon atoms. Formula mercapto compounds, such as 1-n-heptyl-5-mercaptotetrazole or 3-mercapto-5-n-heptyl-
There are oxazole, phenylmercaptotetrazole, quaternary benzothiazole derivatives, and benzotriazole. Preferred compounds are mercapto-substituted pyrimidine derivatives as described in US Pat. No. 3,692,527.

The silver halide emulsions can contain pH controlling ingredients. Preferably, the emulsion layer is coated at a pH value below the isoelectric point of gelatin to improve the stability properties of the coating layer. Other ingredients such as antifoggants, development accelerators, wetting agents, and hardeners for gelatin may be present. The silver halide emulsion layers can contain light screening dyes that absorb scattered light and thus promote image sharpness. Suitable light absorbing dyes are, for example, US-P 4,092,168, US-P4
311787 and DE-P 2453217.

Further details on the composition, preparation and coating of silver halide emulsions can be found in eg Product Licensing Ind.
ex, Volume 92, December 1971, publication 9232
On pages 107-109.

Between the support and the silver halide emulsion layer,
It is preferred to provide a base layer containing an antihalation dye, such as a light absorbing dye, which absorbs the light used for imagewise exposure of the imaging element. Alternatively, micronized carbon black can be used as the antihalation substance. On the other hand, in order to obtain an increase in sensitivity, a light-reflecting pigment such as titanium dioxide can be present in the base layer. In addition, this layer can contain hardening agents, matting agents, such as silica particles, and wetting agents. Suitable matting agents preferably have a number average diameter of 2 to 10 μm, more preferably 2 to 5 μm. Matting agents are generally present in the imaging element at 0.1
used in a total amount of ^{g / m 2 ~2.5g / m 2} . These matting agents and / or light-reflecting pigments can also be present in the silver halide emulsion layer, but most preferably at least 80% by weight can be contained in the silver halide emulsion layer. However, all of the matting agent can be included in the silver halide emulsion layer, with the base layer being substantially free of matting agent. When the entire matting agent is contained in the silver halide emulsion layer, it is preferable to add a non-water-swellable latex to the base layer. Examples of the non-water-swellable latex include a copolymer of styrene and butadiene, polyethyl acrylate, polymethyl methacrylate, a copolymer of acrylate, and a copolymer of methacrylate.
As a further alternative, the light reflecting pigment can be present in another layer provided between the antihalation layer and the photosensitive silver halide emulsion layer. Like the emulsion layer, the base layer is preferably coated at a pH below the isoelectric point of the gelatin in the base layer.

In a preferred embodiment in the context of the present invention, a backing layer is provided on the non-photosensitive side of the support. This layer, which can act as an anti-curl layer, can contain, for example, matting agents such as silica particles, lubricants, antistatic agents, light absorbing dyes, opacifiers such as titanium oxide and customary components such as hardeners and wetting agents. The backing layer can consist of a single layer or a multilayer pack, for example a double layer pack.

The hydrophilic layer usually contains gelatin as a hydrophilic colloid binder. Mixtures of different gelatins with different viscosities can be used to adjust the rheological properties of the layers. However, instead of or with gelatin, one or more other natural and / or synthetic hydrophilic colloids, such as albumin, casein, zein, polyvinyl alcohol, alginic acid or its salts, cellulose derivatives such as carboxymethylcellulose, modified gelatin such as phthaloyl Gelatin or the like can be used.

The hydrophilic layer of the photographic material, especially when the binder used is gelatin, is a suitable hardening agent such as an epoxy type, an ethyleneimine type, a vinylsulfone type such as 1,3-vinylsulfonyl-. 2-Propanol, chromium salts such as chromium acetate and chromium alum, aldehydes such as formaldehyde, glyoxal, and glutaraldehyde, N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin, dioxane derivatives such as 2,3-dihydroxydioxane, active vinyl compounds such as 1,3,5-Triacryloyl-hexahydro-s-triazine, active halogen compounds such as 2,4-dichloro-6-hydroxy-
Curable with s-triazines, and mucohalic acids such as mucochloric and mucophenoxycyclo acids. These curing agents can be used alone or in combination. The binders can also be hardened with fast-reacting hardeners, for example carbamoylpyridinium salts of the type described in U.S. Pat. No. 4,063,952.

The imaging element used according to the invention may further contain various surfactants in the photographic emulsion layer or in at least one other hydrophilic colloid layer. Suitable surfactants include saponins, alkylene oxides such as polyethylene glycol, polyethylene glycol / propylene glycol condensation products, polyethylene glycol alkyl ethers or polyethylene glycol alkyl aryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines Or an alkyl amide,
Nonionic surfactants such as silicone polyethylene oxide adducts, glycidol derivatives, fatty acid esters of polyhydric alcohols and alkyl esters of saccharides; anions containing acid groups such as carboxy, sulfo, phospho, sulfate or phosphate groups Surfactants; amphoteric surfactants such as amino acids, aminoalkyl sulfonic acids, aminoalkyl sulfates or phosphates, alkyl betaines and amine-N-oxides; and alkylamine salts, aliphatic, aromatic or heterocyclic quaternary ammonium salts And a cationic surfactant such as an aliphatic or heterocyclic ring-containing phosphonium or sulfonium salt. Preferably, a compound containing a perfluorinated alkyl group is used. Such surfactants can be used for various purposes, for example as coating aids, as antistatic agents, as compounds for improving lubricity, as compounds for facilitating dispersion emulsification, and as compounds for preventing or reducing adhesion.

The imaging element of the present invention further comprises various other additives such as the compound U, which improves the dimensional stability of photographic materials.
V absorbers, spacing agents, and plasticizers can be included.

Additives suitable for improving the dimensional stability of photographic materials include, for example, dispersions of water-soluble or sparingly soluble synthetic polymers such as alkyl (meth) acrylates, alkoxy (meth) acrylates, glycidyl ( Polymers of (meth) acrylate, (meth) acrylamide, vinyl ester, acrylonitrile, olefin and styrene, or those mentioned above with acrylic acid, methacrylic acid, α, β-unsaturated dicarboxylic acid, hydroxyalkyl (meth) acrylate, sulfoalkyl There are dispersions of (meth) acrylate and styrene sulfonic acid copolymers.

Suitable supports for the imaging element in the context of this invention can be either opaque or transparent,
The latter offers the advantage of exposure through the support, so that the exposure can take place in a camera without a reflector. Specific examples of supports are polyethylene coated paper, polypropylene coated paper, opaque or transparent polyester films, especially polyethylene terephthalate film. Aluminum supports or other hydrophilic supports can also be used as described in the introduction herein. In that case, the image receiving layer is located between the support and the silver halide emulsion layer.

According to a preferred embodiment in connection with the [0057] present invention, it has a thickness of 0.1Mm～0.35Mm, at least 4300N / mm ^2, more preferably at least 4500N / mm ² Young's modulus (E- A polyester film support having a modulus) is used. Young's modulus, also referred to as E-modulus in the context of the present invention, can be measured by Method A according to ANSI-D882-91.

In a practical example, the two main directions of orientation of the polyester film are the machine direction (machine direction).
Or at least 4300 in the direction perpendicular to it (transverse)
It should have an E-modulus of N / mm ² .

According to the most preferred embodiment of the invention,
The polyester film support is isotropic in E-modulus, that is, the ratio of longitudinal E-modulus to transverse direction is 0.8 to 1.3. The use of an isotropic polyester film support offers the advantage that the same printing properties are obtained when the plate is rotated 90 °, thus simplifying making differently sized printing plates from the master roll.

Such an isotropic support also contains an imaging element,
It also offers advantages when used in imagesetters for high intensity short exposures. In this application, several images on one printing plate can be oriented parallel and / or at right angles to the axis of the printing cylinder in the printing press. When using an isotropic polyester film support it makes it very easy to obtain a regular print.

On the other hand, when using an anisotropic polyester film support, generally a large E-modulus in one direction will give rise to a large E-modulus in the direction perpendicular to it. The modulus can be obtained. In order to take advantage of anisotropic polyester supports, such printing plates should be loaded with their E-modulus greater than 4300 N / mm ^{2 at} right angles to the axis of the printing cylinder of the printing press.

The polyester film support is preferably coated with a layer which improves the adhesion of the hydrophilic layer.

A particularly preferred adhesion improving layer comprises a copolymer containing water-soluble and water-insoluble monomers in a molar ratio of 1:99 to 20:80. Preferably, the water-soluble monomer is a monomer having one or more carboxylic acid groups. Examples of particularly preferred copolymers for use in the adhesion improving layer include:
It is a polymer containing 1 to 10% by weight, more preferably 1 to 5% by weight of itaconic acid. Suitable polymers containing itaconic acid include, for example, copolymers of itaconic acid and vinylidene chloride, copolymers of itaconic acid, vinylidene chloride and vinyl acetate, copolymers of itaconic acid, vinylidene chloride and methyl (meth) acrylate. And copolymers of itaconic acid and vinyl chloride, copolymers of itaconic acid, vinyl chloride, vinylidene chloride and methyl (meth) acrylate. In copolymers of itaconic acid, vinylidene chloride and optionally methyl (meth) acrylate, the amount of itaconic acid is 1% to 5%, the amount of vinylidene chloride is 70% to 95%, and methyl (meth) The amount of acrylate is between 0% and 15%. Preferably, the adhesion improving layer does not contain gelatin.

On top of this adhesion-improving layer can be further provided an intermediate layer containing microparticles having a mean diameter of less than 50 nm, preferably colloidal silica and gelatin in a weight ratio of 1: 2 to 2: 1.

According to a preferred method of the invention, the imaging element containing in this order a silver halide emulsion layer and a receiving layer containing physical development nuclei according to the invention on a support is DT.
Imagewise exposure by the R method and subsequent development. The DTR monosheet imaging material in the context of the present invention may be exposed to light in a device according to its particular use, for example with a conventional plate making camera containing a conventional light source or with a high intensity short exposure such as a laser containing device. it can.

The alkaline processing liquid used to develop the imaging element preferably contains at least a portion of the silver halide solvent. Preferably the silver halide solvent is 0.
It is used in an amount of from 01% to 10% by weight, more preferably from 0.05% to 8% by weight. Silver halide solvents suitable for use in connection with the present invention include, for example, 2-
There are mercaptobenzoic acids, cyclic imides, oxazolidones, thiocyanates and thiosulfates. Still other preferred silver halide solvents for use in connection with the present invention are described in EP-A 554584. It should be noted that the effect of the present invention is particularly remarkable when a combination of an alkanolamine and a meso-ion thiolate compound, preferably a meso-ion triazolium thiolate, is used as a silver halide solvent.

According to the invention, the alkaline processing liquid preferably also contains a hydrophobizing agent in order to improve the hydrophobicity of the silver image obtained in the image-receiving surface layer. The hydrophobizing agent used in connection with the present invention can react with silver or silver ions,
Compounds that are hydrophobic, ie, insoluble or only slightly soluble in water. In general, these compounds contain a mercapto or thiolate group and one or more hydrophobic substituents, for example an alkyl group containing at least 3 carbon atoms. Examples of hydrophobizing agents for use according to the invention are eg US-P 3776728, US-P4.
563410 and EP-A554584.

The alkaline processing liquid may also contain the developing agent (s) used in accordance with the present invention. In this case, the alkaline processing liquid is called a developer. On the other hand, some or all of the developing agent can be present in one or more layers of the imaging element.
When all of the developing agent is contained in the imaging element, the alkaline processing liquid is referred to as an activator or liquid.

Silver halide developing agents for use in accordance with the present invention are preferably p-dihydroxybenzene based in combination with a 1-phenyl-3-pyrazolidone based developing agent and / or an auxiliary developing agent which is p-monomethylaminophenol. Of these, for example hydroquinone, methylhydroquinone, or chlorohydroquinone. Particularly useful auxiliary developing agents include those of the phenidone type, such as 1-phenyl-3-pyrazolidone, 1-phenyl-4-monomethyl-3-pyrazolidone, and 1-phenyl-4,4-dimethyl-3-pyrazolidone. is there.
However, other developing agents can be used.

The alkaline processing liquid preferably also contains a preservative having antioxidant activity, for example sulfite ions provided by sodium or potassium sulfite. For example, the aqueous alkaline solution contains sodium sulfite in an amount ranging from 0.15 to 1.0 mol / l. In addition, thickeners such as hydroxyethylcellulose and carboxymethylcellulose, antifoggants such as potassium bromide, potassium iodide and benzotriazole (known to improve print durability), calcium sequestering compounds, sludge prevention Agents and hardeners, including latent hardeners, can be present.

Development acceleration is effected by various compounds for alkaline processing solutions and / or one or more layers of photographic materials, preferably for example US Pat. No. 3,038,805, US Pat.
8075, US-P4292400, US-P4975
This can be achieved with the aid of a polyalkylene derivative having a molecular weight of at least 400 as described in 354.

Following development in the alkaline processing liquid, the surface of the printing plate is preferably neutralized with a neutralizing liquid.

The neutralizing solution generally has a pH of 5-7. The neutralizing solution preferably contains a buffer such as a phosphate buffer, a citrate buffer or mixtures thereof. The neutralizing solution may further comprise a bactericide, for example phenol, thymol, turpi as described in EP 0150517.
nal) or 5-bromo-5-tetro-1,3-dioxane. The liquid is also a substance which affects the hydrophobic / hydrophilic balance of the printing plate obtained after processing of the DTR material,
For example, silica can be contained. Further, the neutralizing solution may contain a wetting agent, preferably a compound containing a perfluorinated alkyl group.

The invention will now be illustrated by the following examples, which should not be construed as limiting the invention thereto. Parts are by weight unless otherwise specified.

EXAMPLE 1 Preparation of Silver Halide Emulsion Coating Solution A silver chlorobromide emulsion consisting of 98.2 mol% silver chloride and 1.8 mol% silver bromide was prepared by the double jet precipitation method.
The average silver halide grain size was 0.38 μm (diameter of a sphere having the same average volume) and contained rhodium ions as internal dopant. The emulsion was stabilized with 1-phenyl-5-mercaptotetrazole and orthochromatically sensitized.

[0076] have a thickness 175μm preparation of image forming material, four polyethylene terephthalate film support provided with adhesive improving layer, the amount of gelatin and 0.4 g / m ² in an amount of respectively 0.4 g / m ² Coated with a layer containing colloidal silica having an average particle diameter of 7 nm. The adhesion improving layer was made of itaconic acid (2
%), A copolymer of vinylidene chloride (88%) and methyl methacrylate (10%).

A silver halide emulsion layer prepared as described above was coated on each of these coated polyethylene terephthalate film supports with an antihalation layer (which is below the silver halide emulsion layer). The amount of gelatin in the anti-ration layer was 2.7 g / m ^2, and for the silver halide emulsion layer it was 1.34 g / m ² .
The amount of silver halide expressed as AgNO ₃ is 1.25
g / m ² , and the emulsion layer further contained 120 mg / m ² formaldehyde as a developing agent and a hardening agent. The antihalation layer further contained a silica matting agent having an average particle size (weight average diameter) of 3.4 μm and carbon black as an antihalation means. The material thus obtained was kept at 57 ° C. at a relative humidity of 34% per day.

The material thus obtained was coated with a PdS core layer, the core having a number average diameter of 1.8 nm and 4.5 n
The fraction with a diameter greater than m was 2%. The nucleus is E
Made as described in Example 2 of P546598 and contained polyvinyl alcohol as a stabilizer.

Some materials were obtained as described above,
Polyacrylamide and / or Laponite was added as shown in Table 1 below. The nuclear layers for each of the four materials include
Also included was 0.4 g / m ² hydroquinone and 30 mg formaldehyde. After coating the surface layer, 1 for each material
The day was kept at 57 ° C and a relative humidity of 34%.

The following alkaline treatment solutions were made: sodium hydroxide 30 g methylhydroquinone 2 g anhydrous sodium sulfite 35 g amino-ethylaminoethanol 45 ml compound A (shown below) 0.8 g EDTA.4Na 1 g 3-mercapto-5-n- Heptyl oxadiazole 0.35 g made up to 1 liter with water. EDTA · 4Na is a sodium salt of ethylenediaminetetraacetic acid.

[0081]

Embedded image

The following neutralization solution was made: citric acid 10 g sodium citrate 35 g anhydrous sodium sulfite 5 g phenol 50 mg made up to 1 liter with water.

The following dampening liquid was prepared: Water 880 ml Citric acid 6 g Boric acid 8.4 g Anhydrous sodium sulfite 25 g Ethylene glycol 100 g Colloidal silica 28 g

Imagewise exposing the aforesaid imaging element,
It was treated with the above-mentioned alkaline treatment solution at 30 ° C., followed by neutralization with the above-mentioned neutralization solution at 25 ° C. and drying.

The printing plate thus prepared was mounted on an offset printing machine (two-color GTO printing machine). The moisturizing solution described above was used during printing. The print results for each of the printing plates were evaluated by print durability, toning (ink acceptance in the starting non-image areas) and ink acceptance.

Toning was evaluated as the number of copies required before a clean copy without toning was obtained:

×:> 350 −: 150 to 350 Δ: 50 to 150 ○: <50

The ink receptivity number is based on the fresh processing solution (fre
sh) and with the processing solution (reg.) that was put to use for a substantial amount of time, evaluated as the number of copies required to obtain a stable density of the image.

X:> 75 −: 50 to 75 Δ: 20 to 50 ○: <20

Print durability was evaluated as the number of acceptable quality copies that could be obtained:

X: <5000 −: 5000 to 15000 Δ: 15000 to 30000 ○:> 30000

[0092]

[Table 1]

Example 2 Imaging materials and printing plates were prepared as described in Example 1, except that instead of polyacrylamide, a copolymer of 99 mol% acrylamide and 1 mol% styrene (PA) was used.
MS) copolymer, polyacrylic acid (PA
Z) was added and modified in the amounts shown in Table 2. The printing plate was evaluated as described in Example 1.

[0094]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Roney de Clark Septratart, Mortzel, Belgium 27 Agfa Gewert Namrose Rose Bennault Chap

Claims (11)

[Claims] 1. An image forming material for producing a lithographic printing plate by a silver salt diffusion transfer treatment, wherein the image forming material is
On a support, containing a silver halide emulsion layer and a receiving layer,
An image forming material characterized in that the receiving layer contains (i) physical development nuclei, (ii) an inorganic colloidal substance, and (iii) a hydrophilic polymer which is a homopolymer or copolymer of acrylamide or methacrylamide. . 2. The imaging element according to claim 1, wherein the inorganic colloidal material is colloidal clay. 3. The imaging element according to claim 2, wherein the colloidal silica is a synthetic smectite clay. 4. The imaging element of claim 2, wherein the colloidal clay is a synthetic laponite clay. 5. The image-forming material according to claim 1, wherein the inorganic colloidal substance and the physical development nuclei are dispersed as discrete particles in the hydrophilic polymer. . 6. The physical development nuclei have an average diameter of less than 6 nm and the number of nuclei having a diameter of greater than 4.5 nm is:
2. It is less than 15% of the total number of nuclei.
Item 5. The image forming material according to any one of items 5 to 5. 7. The hydrophilic polymer is a copolymer of acrylamide or methacrylamide and a comonomer having a heterocyclic group having at least N, O or S atoms. The image-forming material according to any one of 1. 8. The imaging element according to claim 7, wherein the comonomer has an imidazole or pyridine group. 9. The hydrophilic polymer is vinyl imidazole, styrene, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl acetate,
7. A copolymer of one or more comonomers selected from the group consisting of vinyl chloride, vinylidene chloride, itaconic acid, vinylpyrrolidone and vinylpyridine, and acrylamide or methacrylamide, wherein the copolymer is acrylamide or methacrylamide. Image forming material. 10. The image forming material according to claim 1, wherein the image receiving layer further contains polyvinyl alcohol and / or poly (meth) acrylic acid. 11. Use of the image-forming material according to claim 1 for making a lithographic printing plate by a silver salt diffusion transfer process.