JPH07271042A - Manufacture of printing board based on image forming elementand silver-salt diffusion transfer method - Google Patents

Abstract

PURPOSE: To provide a printing plate produced by a silver salt diffusion transfer method using an image forming element and to provide a printing plate having such improved printing property that the number of copies as wastes in the initial stage of a printing process can be decreased. CONSTITUTION: This image forming element has a photosensitive layer containing a silver halide emulsion and an image accepting layer containing physical developing nuclei, and these layers are formed in this order on a base body. The base body consists of a polyester film having 0.1 to 0.35 mm thickness and at least 4300 N/mm<2> Young's modulus.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to lithographic printing plates obtained according to the silver salt diffusion transfer process. In particular, the invention relates to improving the lithographic properties of such printing plates.

[0002]

BACKGROUND OF THE INVENTION The principle of the silver complex diffusion transfer inversion method, hereinafter referred to as the DTR-method, is described, for example, in US Pat. No. 2,352,014 and the book "Photograph by Andree Rott and Edith Weyde". Silver Halide Diffusion Pro
cesses '', The Focal Press, London and New Yor
k), (1972).

In the DTR-method, the undeveloped silver halide of a photographic silver halide emulsion layer material that has been information-wise exposed is converted into a soluble silver complex compound using a so-called silver halide solvent, which is the image receiving material. It is diffused into the element and reduced therein with a developer, generally in the presence of physical development nuclei, and inverted with respect to the black silver image obtained on the exposed portion of the photographic material. To produce a silver image (DTR-image) having different image density values.

The DTR-image bearing material can be used as a planographic printing plate in which the DTR-silver image portion produces a water repellent ink receptive portion on a water receptive ink repellent background. Can the DTR-image occur in the image-receiving layer of a sheet or web material that is a separate element with respect to photographic silver halide emulsion materials (so-called 2-sheet DT)?
R element), or a so-called single support element image receiving layer, also referred to as a mono-sheet element containing at least one photographic silver halide emulsion layer in water permeable relationship with the image receiving layer. Can happen. The latter mono-sheet method is preferred for the production of offset printing plates by the DTR method. For example, British Patent Specification No. 1,241,6
No. 61 discloses a method of making a planographic printing plate consisting of a sheet material comprising an outer hydrophilic colloid layer, on the surface of which silver complex diffusion from an underlying silver halide emulsion layer is exposed. The silver image produced by the transfer reversal method is concentrated. The silver image formed on the surface is dampening
Suitable for printing images with lithographic printing methods using iquid).

The latter type of commercial lithographic printing plate precursors typically have therein a base layer, a silver halide emulsion layer and a silver image which act as anti-halation layers in the order shown below. The surface layer containing physical development nuclei contains a flexible support such as polyester or paper.

Such lithographic printing plates, also referred to as imaging elements, can be camera exposed or they can be scanning exposed, for example laser or LED exposed. The latter offers the advantage of simplifying the production of printing plates in that the paste-up used for the exposure of the imaging element can be completely produced by computer. The computer-generated veneer is then transferred to an image setter that is equipped with, for example, a laser that processes the exposure of the imaging element.

Lithographic printing plates obtained according to silver salt diffusion transfer are generally compared to aluminum-based printing plates using a diazo composition or a photopolymer composition as a photosensitive coating for producing the printing plate. However, the print durability is limited. Lithographic printing plates obtained according to the DTR-method are generally used for short-duration printing operations, where copy number is less important, but ease and speed of manufacture of the printing plate are important.

In such short-time printing operations, it is also desirable to keep the number of copies that must be discarded at the beginning of the printing operation to a minimum in order to increase the production efficiency of the printing process. Unfortunately, DTR-type lithographic printing plates produce a large number of copies due to non-uniform ink acceptance, hue changes between copies at the start of color printing, and image distortion. Must be discarded at the beginning of the printing process. In addition, many adjustments of the printing machine are necessary to get a satisfactory printed copy during the start-up.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for making imaging elements and printing plates using the same according to the silver salt diffusion acid transfer process, which printing plates are improved lithographic printing. It has properties, especially the reduction in the number of copies that must be discarded at the start of the printing operation.

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

According to the present invention there is provided an imaging element comprising on a support a light-sensitive layer comprising a silver halide emulsion and an image-receiving layer comprising physical development nuclei in the order listed. An imaging element is provided wherein the support is a polyester film having a thickness between 0.1 mm and 0.35 mm and a Young's modulus of at least 4300 N / mm ² .

According to the invention, the image-forming element as defined above is image-wise exposed, and the image-wise exposed image-forming element thus obtained is then developed with a silver halide solvent and a developing agent. There is also provided a method of making a lithographic printing plate comprising the step of developing with an alkaline processing solution in the presence of a base agent.

[0013]

Detailed Description of the Invention 0.1 mm as support for printing plates
Thickness between ~ 0.35 mm and at least 4300 N /
mm ² , and more preferably at least 4500 N /
It has been found that by using a polyester film having a Young's modulus (E-modulus) of mm ² , it is possible to reduce the number of copies that have to be discarded at the start of the printing operation when using a printing plate obtained according to the DTR-method. .

Young's modulus, also referred to as E-modulus, can be measured according to the ANSI-D882-91 standard for the purposes of the present invention.

According to the invention, at least one of the two main orientation directions of the polyester film, that is to say the machine direction (longitudinal direction) or the direction perpendicular thereto (transverse direction), has an E-modulus of at least 4300 N / mm ^2. You have to do it.

According to the most preferred embodiment of this invention, the polyester support is isotropic in E-modulus,
That is, the ratio of E-modulus in the vertical direction to the horizontal direction is 0.8.
It is between ~ 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 °, which simplifies the production of printing plates of different dimensions coming out of the master roll.

Such an isotropic support also provides advantages when the imaging element is used in an imagesetter for high intensity short exposures. In this application, 5 on one printing plate
Three or six images can be oriented parallel and / or perpendicular to the axis of the printing cylinder in the printing machine. When using an isotropic polyester film support, it becomes much easier to obtain a consistent print.

On the other hand, when using an isotropic polyester film support, a relatively large E-modulus can be obtained because a large E-modulus in one direction damages the E-modulus in the direction perpendicular thereto. In order to take advantage of the isotropic polyester film support, one must install a printing plate with an E-modulus greater than 4300 N / mm ² perpendicular to the axis of the printing cylinder of the printing press.

The polyester film according to the invention is preferably a polyethylene terephthalate film, but other polyester films can be used according to the invention. The polyester film according to the invention may be uniaxially oriented, but is preferably biaxially oriented. The desired E-modulus can be obtained by setting the degree of orientation of the polyester film. Preferably, the degree of orientation is such that the polyester film has a longitudinal and / or transverse direction of 1: 2 to 1:
It is obtained by stretching at a ratio between 4.

The E-modulus also refers to certain materials in polyester films, such as low molecular weight compounds, BaS.
It can also be affected by adding voiding agents such as O ₄ , polypropylene, and opacifying agents such as TiO ₂ .

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

A particularly suitable adhesion-improving layer comprises a copolymer containing water-soluble monomers and water-insoluble monomers in a molar ratio between 1:99 and 20:80. Suitably, the water soluble monomer is a monomer having one or more carboxylic acid groups. An example of a copolymer that is particularly suitable for use in the adhesion improving layer is a polymer containing 1-10 wt%, more preferably 1-5 wt% itaconic acid. Suitable polymers containing itaconic acid include, for example, itaconic acid and vinylidene chloride copolymers, itaconic acid, vinylidene chloride and vinyl acetate copolymers, itaconic acid,
Examples thereof include a copolymer of vinylidene chloride and methyl (meth) acrylate, a copolymer of itaconic acid and vinyl chloride, a copolymer of itaconic acid, vinyl chloride, vinylidene chloride and methyl (meth) acrylate. The amount of itaconic acid is between 1% and 5% and the amount of vinylidene chloride is between 70% and
Copolymers of itaconic acid, vinylidene chloride and optionally methyl (meth) acrylate, which are between 95% and the amount of methyl (meth) acrylate is between 0% and 15%, are preferred. The adhesion improving layer preferably contains no gelatin.

On top of this adhesion-improving layer are fine particles with a mean diameter of less than 50 nm, preferably 1: 2 to 2:
It is also possible to provide another intermediate layer containing colloidal silica and gelatin in a weight ratio of 1.

One or more photographic silver halide emulsions used in accordance with the present invention are described, for example, by P. Glafkides, "Photographic Chemistry and Physics (Chimie et al.
Physique Photographique), Paul Montell (Paul
Montel), Paris (1967), GF Duffin
`` Photographic Emulsion Chemistr
y) ”, The Focal Press, London (1966), and VL Zelikman (Zelikma)
n), "Making and C
oating Photographic Emulsion) ", The Focal
It can be prepared from soluble silver salts and soluble halides according to various methods as described by Press, London (1966).

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

The silver halide grains of the photographic emulsion used in accordance with the present invention may have a regular crystalline form such as a cubic or octahedral form, or they may have a transition form. They may have an irregular crystalline form, such as spherical or tubular, or else have a complex crystalline form comprising a mixture of the ordered and irregular crystalline forms. Good.

According to the present invention, one or more emulsions preferably consist essentially of silver chloride, although 1 mol%
Silver bromide moieties in the range of -40 mol% may be present. The emulsions preferably belong to the core / shell form, which is well known to the person skilled in the art in the sense that substantially all the bromide is concentrated in the core. The core preferably contains 10 to 40% of the total silver halide precipitated, while the shell preferably constitutes 60 to 90% of the total silver halide precipitated.

The average size of silver halide grains is from 0.10 to 10.
The range is 0.70 μm, preferably 0.25 to 0.6 μm.

The size distribution of the silver halide grains of the photographic emulsion used in accordance with the present invention may 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 particle size.

Preferably during the precipitation stage iridium and / or
Alternatively, the rhodium-containing compound or a mixture of both is added. The concentration range of these added compounds is 10 ^-8 to 10 ^-3 mol, preferably 1 mol / mol AgNO _3.
The range is between 10 ^{−7 and} 10 ⁻⁶ mol per mol AgNO ₃ . This results in an increase in small amounts of iridium and / or rhodium, so-called iridium and / or rhodium dopants in the silver halide crystal lattice. As is known to those skilled in the art, many scientific and patent documents disclose iridium or rhodium containing compounds during emulsion preparation or compounds containing other elements of Group VIII of the Periodic Table.

The emulsion can be chemically sensitized, for example by adding sulfur-containing compounds such as allyl isothiocyanate, allylthiourea, and sodium thiosulfate during the chemical ripening step. Also, reducing agents such as Belgian Patent Nos. 493,464 and 568,68.
The tin compounds described in No. 7 as well as polyamines such as diethylenetriamine or derivatives of aminomethane-sulphonic acid can be used as chemical sensitizers. Other suitable chemical sensitizers are noble metals and noble metal compounds such as gold, platinum, palladium, iridium, ruthenium and rhodium. This chemical sensitization method is performed by R. Koslowsky, Z. Wiss. Photogr. Photoph
ys. Photochem., 46, 65-72 (1951).

Emulsions of DTR elements can be spectrally sensitized according to the spectral radiation of the exposure source for which the DTR element is designed.

Sensitizing dyes suitable for the visible spectral region include, for example, FM Hamer "The Cyanine Dyes and Related Compounds",
1964, John Willie and Sons (John
The methine dyes described by Wiley & Sons) are included. Dyes that can be used for this purpose include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, homopolar cyanine dyes, hemicyanine dyes,
Included are styryl dyes and hemioxonol dyes. Particularly valuable dyes belong to cyanine dyes, merocyanine dyes, and complex merocyanine dyes.

Silver halide emulsions include common stabilizers such as homopolar or salt compounds of mercury with aromatic or heterocyclic rings such as mercaptotriazoles, simple mercury salts, sulfonium mercury double salts and other mercury. A compound can be included. Other suitable stabilizers are azaindenes, preferably tetra- or penta-azaindenes,
Particularly those substituted with hydroxy or amino groups. This kind of compound is from Z. Wiss. Photog of BIRR.
r. Photophys. Photochem., 47, 2-27 (195
2). Other suitable stabilizers are heterocyclic mercapto compounds such as phenylmercaptotetrazole, quaternary benzothiazole derivatives, and benzotriazole. The preferred compound is US Pat.
Mercapto-substituted pyrimidine derivatives as disclosed in 2,527.

The silver halide emulsions can contain pH adjusting ingredients. Preferably, the emulsion layer is coated at a pH value below the isoelectric point of gelatin to improve the stability properties of the coated layer. Other ingredients, such as antifoggants, development accelerators, wetting agents, and hardeners for gelatin can be present. The silver halide emulsion layer can also comprise light-screening dyes that absorb diffuse light and thus promote image sharpness. Suitable light-absorbing dyes are, for example, US Pat. No. 4,092,
168, U.S. Pat. No. 4,311,787 and German Patent No. 2,453,217.

Further details regarding the composition, manufacture and coating of silver halide emulsions can be found, for example, in the Product Licensing Index.
ndex), vol. 92, December 1971, reference number 923.
2, pp. 107-109.

The layer containing physical development nuclei is preferably free of hydrophilic binder, but contains a small amount of hydrophilic colloid, eg polyvinyl alcohol, up to 30% by weight of the total weight of the layer. Hydrophilicity can also be improved. Preferred development nuclei for use in accordance with the present invention are heavy metal sulfides such as antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, platinum, silver, and zinc sulfides. Particularly suitable development nuclei for the present invention are palladium sulphide nuclei. Other suitable development nuclei are heavy metal salts such as selenides, polyselenides, polysulfides,
These are mercaptans and tin (II) halides. Heavy metals, preferably silver, gold, platinum, palladium, and mercury can be used in colloidal form.

In order to obtain the maximum benefit from the present invention, especially in order to further reduce the number of copies that have to be discarded at the start and / or to improve the print resistance, the image-receiving layer is preferably below 6 nm. Of physical development nuclei having a number average diameter of less than 15% of the number of nuclei contained in the image-receiving layer, and most preferably Pds-nuclei. It consists of Preferably, the number average diameter is less than 3.5 nm.

Furthermore, the physical development nuclei are preferably used in combination with hydrophilic polymeric binders having functional groups which give an affinity for the nuclei. Examples of suitable functional groups are (i)
Heterocyclic ring systems having at least one N, O or S atom, (ii) thioethers, thiol and thioxo groups, (iii) amide and guanidino groups. Specific examples of functional groups are imidazoles, imidazolines, pyrazoles, thiazolidines, thiazolidones, thiazolones, indazoles, pyridines, thyrazines, benztriazoles, tetrazoles and the like.

These functional groups are preferably present in the structural units of the polymeric binder in an amount of 1 to 20 mol% of the polymer. The hydrophilicity of the binder is obtained from hydrophilic groups contained in the polymer such as hydroxy, carboxyl, sulfonyl and the like. Examples of suitable polymers are US Pat.
No. 160 670, which is incorporated herein by reference.

Between the support and the silver halide emulsion layer is preferably a base layer which preferably contains an anti-halation material such as a light absorbing light absorbing dye used for the imagewise exposure of the imaging element. Be used for. Alternatively, finely divided carbon black can be used as an anti-halation material. On the other hand, light-reflecting pigments such as titanium dioxide can also be present in the base layer in order to obtain sensitization. In addition, this layer can also contain hardening agents, matting agents such as silica particles, and wetting agents. Suitable matting agents are preferably 1-10 μm, and more preferably 2 μm.
It has an average diameter between m-5 μm. Matting agents are generally present in the imaging element between 0.1 and 2.5 g / m ² . At least some of 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, are present in the base layer. Alternatively, the light reflective pigment can be present in a separate layer provided between the antihalation layer and the light sensitive silver halide emulsion layer. Like the emulsion layer, the base layer also preferably has a p below the isoelectric point of the gelatin in the base layer.
Coated at H value.

In a preferred embodiment of the present invention, the backing layer (b
An acking layer) is provided on the non-light sensitive side of the support. This layer, which can function as an anti-curl layer, is for example a matting agent,
For example, silica particles, lubricants, antistatic agents, light absorbing dyes, opacifying agents such as titanium oxide, and common ingredients such as hardening agents and wetting agents can be contained. The backing layer may be a single layer or may consist of a double layer pack.

[0043] According to a preferred embodiment in connection with the present invention, the rough surface of the backing layer package is adjusted to arithmetical Chuko deviations greater than 0.7 profile R _a is obtained. _Ra is the following formula:

[0044]

[Equation 1]

(Where m is 0.8).

The printing plates of the back side of the R _a - value at the time of smaller than 0.7, the number of copies that have to be disposed at the start of the printing process would typically much. However,
If R _a is lower than 0.15, an improvement is obtained when the back side of the printing plate is at least partially wet when installed on the printing cylinder.

The hydrophilic layer generally contains gelatin as a hydrophilic colloid binder. Mixtures of different gelatins with different viscosities can be used to control the rheological properties of the layer. Instead of or together with gelatin, one or more other natural and / or synthetic hydrophilic colloids such as albumin, casein, zein, polyvinyl alcohol, alginates or their salts, cellulose derivatives such as carboxy. Methylcellulose, modified gelatin such as phthaloyl gelatin and the like can also be used.

The hydrophilic layer of the photographic element is a suitable hardener, such as of the epoxide type, of the ethyleneimine type, of the vinylsulfone type, for example 1, especially when the binder used is gelatin. 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 methyloldimethylhydanthrin, dioxane derivatives such as 2,3-dihydroxy-dioxane, active vinyl compounds such as 1,3,5-triacryloyl-hexahydro-s -Triazines, active halogen compounds, eg 2,4
It can be hardened with -dichloro-6-hydroxy-s-triazine and mucohalogen acids such as mucochloric acid and mucophenoxychloric acid. These hardeners can be used alone or in combination. The binders can also be hardened with fast-reacting hardeners, such as carbamoylpyridinium salts of the type described in US Pat. No. 4,063,952.

The imaging element used in accordance with the present invention may further comprise various types of surfactants in the photographic emulsion layer or in at least one other hydrophilic colloid layer. Suitable surface-active agents include nonionic surface-active agents such as saponins, alkylene oxides such as polyethylene glycol, polyethylene glycol / polypropylene glycol condensation products, polyethylene glycol alkyl ethers or polyethylene glycol alkylaryl ethers, polyethylene glycol. Esters, polyethylene glycol sorbitan esters,
Polyalkylene glycol alkylamines or alkylamides, silicone-polyethylene oxide adducts, glycidol derivatives, fatty acid esters of polyhydric alcohols and alkyl esters of sugars; eg of carboxy, sulfo, phospho, sulfuric acid or phosphoric acid ester groups Anionic activators comprising acid groups such as; amphoteric activators such as amino acids, aminoalkyl sulfonic acids,
Aminoalkyl sulfates or sulfates, alkyl betaines, and amine-N-oxides; and cationic activators, such as alkyl amine salts, aliphatic, aromatic or heterocyclic quaternary ammonium salts, aliphatic or heterocyclic Included are cyclic ring-containing phosphonium or sulfonium salts. Compounds containing perfluorinated alkyl groups are preferably used. Such surface-active agents are used for various purposes, for example as coating aids, as antistatic compounds, as slidability-improving compounds, as compounds promoting dispersion emulsification and for preventing or reducing adhesion. It can be used as a compound.

The imaging element of the present invention may further contain various other additives such as compounds which improve the dimensional stability of photographic elements, UV absorbers, spacing agents and plasticizers.

Additives suitable for improving the dimensional stability of photographic elements are, for example, water-soluble or sparingly soluble synthetic polymers such as alkyl (meth) acrylates, alkoxy (meth) acrylates, glycidyl (meth) acrylates, Polymers of vinyl esters, acrylonitriles, olefins, and styrenes, or the above with acrylic acid, methacrylic acid, alpha-beta-unsaturated dicarboxylic acids, hydroxy (meth) acrylates, sulfoalkyl (meth) acrylates And a dispersion of a copolymer with styrene sulfonic acid.

According to the invention, the imaging element described above is image-wise exposed and then developed according to the DTR-method. The DTR mono-sheet imaging element in connection with the present invention can be image-wise exposed in an apparatus according to its particular application, such as a conventional plate making camera containing a conventional light source or a laser containing apparatus.

The alkaline processing liquid used to develop the imaging element in accordance with the method of the present invention preferably contains at least a portion of one or more silver halide solvents. Suitably, the silver halide solvent is 0.01% by weight.
Between 10% by weight and more preferably 0.05% by weight
Used in an amount between ˜8% by weight. Suitable silver halide solvents for use in connection with the present invention are, for example, 2-mercaptobenzoic acid, cyclic imides, oxazolidines, thiocyanates and thiosulfates. Other silver halide solvents suitable for use in connection with the present invention are described in EP-A-554584.

According to the present invention, the alkaline processing liquid preferably contains a hydrophobizing agent for improving the hydrophobicity of the silver image obtained in the image receiving layer. The hydrophobizing agents used in the context of the present invention are compounds which are capable of reacting with silver or silver ions and which are hydrophobic ie insoluble in water or slightly soluble in water. Generally, these compounds contain a mercapto group or thiolate group and one or more hydrophobic substituents, such as an alkyl group having at least 3 carbon atoms. Examples of hydrophobizing agents for use in accordance with the present invention are, for example, those described in US Pat. No. 3,776,728 and US Pat. No. 4,563,410.

The alkaline processing liquid may contain one or more developing agents used in accordance with the present invention. In this case, the alkaline processing liquid is called a developer. On the one hand, some or all of the one or more developing agents can be present in one or more layers of the imaging element. When all of the developer is included in the imaging element, the alkaline processing liquid is called the activator or activating liquid.

Silver halide developing agents suitable for use in accordance with the present invention are preferably of the p-dihydroxybenzene type,
For example hydroquinone, methylhydroquinone or chlorohydroquinone, which are preferably auxiliary developing agents (auxiliaries).
iliary developing agent) and the secondary developing agent is a 1-phenyl-3-pyrazolidinone-type developing agent and / or p-monomethylaminophenol. Particularly useful secondary developing agents are of the phenidone type, such as 1-phenyl-3-pyrazolidinone, 1-phenyl-4-monomethyl-3-pyrazolidinone, and 1-phenyl-4,4-dimethyl-3-pyrazolidinone. However, other developing agents can be used.

The alkaline processing liquid also preferably contains a preservative having antioxidant activity, for example sulfite ions provided by sodium or potassium sulfite. For example, the alkaline aqueous solution contains sodium sulfite at 0.15 to
It comprises an amount in the range of 1.0 mol / l. In addition, thickeners such as hydroxyethyl cellulose and carboxymethyl cellulose, fogging inhibitors such as potassium bromide, potassium iodide, and benzotriazoles, calcium-scavenging compounds, anti-sludge agents known to improve print resistance. , And latent hardeners can also be present.

Various compounds for the alkaline processing liquid and / or one or more layers of the photographic element, preferably for example US Pat. Nos. 3,038,805, 4,0.
38,075, 4,292,400, 4,975,
Development can be accelerated with polyalkylene derivatives having a molecular weight of at least 400 as described in U.S. Pat.

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

The neutralizing liquid generally has a pH between 5 and 7. The neutralizing solution is preferably a buffer, such as a phosphate buffer,
Contains citrate buffer or mixtures thereof. The neutralizing solution may also be a bactericide, for example European Patent No. 0,1.
It may also contain phenol, thymol or 5-bromo-5-nitro-1,3-dioxane as described in 50,517. The liquid can also contain substances which influence the hydrophobic / hydrophilic balance of the printing plate obtained after the treatment of the DTR element, for example silica. In addition, the neutralizing solution may also contain wetting agents, preferably compounds containing perfluorinated alkyl groups.

The invention will now be described by the following examples, without intending to limit it thereto. All parts are by weight unless otherwise noted.

[0062]

【Example】

Preparation of Silver Halide Emulsion Coating Solution A silver chlorobromide emulsion consisting of 98.2 mol% chloride and 1.8 mol% bromide was prepared by the double jet precipitation method. The average silver halide grain size was 0.4 μm (equal volume sphere diameter) and contained rhodium ions as an internal dopant. The emulsion was orthochromatically exposed and stabilized with 1-phenyl-5-mercapto-tetrazole.

Preparation of Imaging Elements A triaxially oriented polyethylene terephthalate film support containing gelatin having a thickness of 175 μm and an E-modulus shown in Table 1 and provided with an adhesion-improving layer containing gelatin. the amount of 0.4 g / m ² with a layer a and 0.4 g / m ² colloidal silica having an average particle lineal 7nm
The amount of each was coated. The adhesion improving layer contained itaconic acid (2%), vinylidene chloride (88%) and methylmethacrylate (10%).

The emulsion prepared as described above was coated on a polyethylene terephthalate film support together with a base layer so that the amount of gelatin in the base layer was 2.7 g / m ² and a silver halide emulsion. 1.3 for layers
It was coated at 4 g / m ² . The amount of silver halide expressed as AgNO ₃ is 1.25 g / m ^2, and the emulsion layer further developer and 120 mg / m
^It also contained formaldehyde as a hardener of ² .
The anti-halation layer also contained a silica matte having an average particle size of 3.4 μm and carbon black as an anti-halation agent.

The element thus obtained was kept at 57 ° C. and 34% relative humidity for 1 day.

The element thus obtained was then coated with a surface layer of PdS nuclei which acted as physical development nuclei. The surface layer also contained 0.4 g / m ² hydroquinone and 70 mg formaldehyde. The material was then stored at 57 ° C and 34% relative humidity for 1 day.

The following alkaline treatment solutions were prepared: sodium hydroxide (g) 30 anhydrous sodium sulfite (g) 33 potassium thiocyanate (g) 20 3-mercapto-4-acetamido-5-n.heptyl-1,2. , 4-Triazole (g) 0.15 Make up to 1 liter with water.

The following neutralization solution was prepared: 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 fountain solution was prepared: water 880 ml citric acid 6 g boric acid 8.4 g anhydrous sodium sulfate 25 g ethylene glycol 100 g colloidal silica 28 g.

The above imaging element was image-wise exposed and treated at 30 ° C. with one of the above alkaline processing solutions, then at 25 ° C. neutralized with the above neutralizing solution and dried.

The printing plate thus produced was placed on an offset machine (two-color GTO printing machine) so that the direction corresponding to the E-modulus in Table 1 was perpendicular to the axis of the printing cylinder. The printing press was equipped with a clamp system for installing the plate. The ink used was a commonly used ink. Blue ink and black ink K + E 4F 473 and black ink K
+ E 125 were used, each of which was available from BASF. The above dampening solution was used during printing experiments. The number of copies that had to be discarded before a consistent print was obtained was evaluated. The results are shown in the table below.

Table 1 Sample No. E-modulus (N / mm ² ) Number of copies that had to be discarded 1 4230 200 2 * 4769 100 3 5350 75 (*) Polyethylene terephthalate film is isotropic and the results obtained are plates. Were virtually the same regardless of the method in which they were installed.

The main features and aspects of the present invention are as follows.

1. An imaging element comprising on a support a light sensitive layer comprising a silver halide emulsion and an image receiving layer comprising physical development nuclei in the order listed, said support being from 0.1 mm to 0.1 mm. Thickness between 35 mm and at least 43
An imaging element, which is a polyester film having a Young's modulus of 00 N / mm ² .

2. 1 above, wherein the polyester film support has a Young's modulus of at least 4500 N / mm ^2.
Imaging element according to.

3. An imaging element according to claim 1 or 2 wherein the ratio of Young's modulus in the machine direction to Young's modulus in the cross direction is between 0.8 and 1.3.

4. One or more backing layers on the side of the support opposite the side containing the photosensitive layer
The surface of which and backing coat layer provided there is at least 0.7 or 0.15 or more profile R _a of the arithmetic mean deviation (arithmetical mean deviation), the imaging element according to any of the above terms.

5. An imaging element according to any of the preceding clauses wherein the polyester film is biaxially oriented polyethylene terephthalate.

6. The physical development nuclei have a number average diameter of 6 nm or less and are contained in the image receiving layer at 4.5n.
An imaging element according to any of the preceding clauses wherein the number of physical development nuclei having a diameter greater than m is less than 15% of the total number of physical development nuclei contained in said image receiving layer.

7. The image-forming element according to any of the above paragraphs is image-wise exposed and the image-wise exposed image-forming element thus obtained is then subjected to an alkaline treatment in the presence of a silver halide solvent and a developing agent. A method of manufacturing a lithographic printing plate, comprising the step of developing with a solution.

Claims (2)

[Claims] 1. An imaging element comprising a photosensitive layer comprising a silver halide emulsion and an image receiving layer comprising physical development nuclei on a support in the order recited, wherein the support is 0. A thickness between 0.1 mm and 0.35 mm and at least 43
An imaging element, which is a polyester film having a Young's modulus of 00 N / mm ² . 2. An image-wise exposure of the image-forming element according to claim 1 and then the image-wise exposed image-forming element thus obtained in the presence of a silver halide solvent and a developing agent. A method of making a lithographic printing plate comprising the step of developing with an alkaline processing solution.