JP3394128B2 - Lithographic printing plate - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lithographic printing material to which a silver complex salt diffusion transfer method is applied.

[0002]

2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image-forming portion that accepts oil-based ink and an oil-repellent non-image-forming portion that does not receive ink. Generally, the non-image-forming portion is hydrophilic to receive water. It is composed of sex parts. In ordinary lithographic printing, both water and ink are supplied to the plate surface, the image area selectively receives the coloring ink, and the non-image area selectively receives water, and the ink on the image area, such as paper Printing is performed by transferring it to a printing medium.

Therefore, in order to obtain a good printed matter, the difference in lipophilicity and hydrophilicity between the image area and the non-image area is sufficiently large, and the image area is sufficient when water and ink are supplied to the plate surface. It is necessary to accept a certain amount of ink and not to accept ink in the non-image area.

A lithographic printing plate using a silver complex salt diffusion transfer method (DTR method), particularly a lithographic printing plate having a physical development nucleus layer on a silver halide emulsion layer is described in, for example, US Pat. No. 3,72.
No. 8,114, No. 4,134,769, No. 4,1
No. 60,670, No. 4,336,321, No. 4,
No. 501,811, No. 4,510,228, No. 4,621,041 and the like. The exposed silver halide crystals cause chemical development by DTR development to give a black color. It becomes silver and forms a hydrophilic non-image area, while unexposed silver halide crystals become a silver salt complex by the silver salt complexing agent in the developing solution and diffuse to the physical development nucleus layer on the surface to form nuclei. In the presence of the above, physical development is caused to form an image area mainly composed of ink-receptive physically developed silver.

As described above, in the planographic printing plate, gelatin-
Since the silver image deposited on the physical development nucleus layer on the silver halide emulsion layer is used as the ink-receptive image area, the image area is larger than that of a general lithographic printing plate (eg PS plate). There is a defect that the resistance to mechanical abrasion of the image part is insufficient, the image part is missing, and the ink receiving property of the image part is gradually lost.

In order to overcome this drawback, the hardness of gelatin is increased, a matting material is contained in an undercoat layer or a silver halide emulsion layer to improve abrasion resistance, and the amount of physical development nuclei is increased. Then, dirt was generated. Further, when the planographic printing plate is manufactured and stored for a long period of time from the time when the plate is made, there are drawbacks such that scumming occurs and the ink receptivity deteriorates.

Further, if the hardness of gelatin is increased or the amount of physical development nuclei is increased, uneven coating properties of the physical development nuclei layer frequently occur, and the printing durability is seen in the unevenness. Dirt,
The effects on ink deposits and ink deposits are seen, and improvements are desired.

In order to improve the water retention, JP-A-4-4-2
In 77747, it is proposed to include pullulan in the physical development nuclei layer and / or the layer adjacent thereto, and JP-A-4-277748 and 5-88370.
Although a hydrophilic polymer has been proposed, the level of improvement has not reached a sufficient level. Also,
If a large amount of hydrophilic polymer is used, ink-carrying tends to be poor.

To improve printing durability, Japanese Patent Publication No. 62-
296143, Japanese Examined Patent Publication Nos. 63-226658 and 63
No. 249852, Japanese Patent Publication No. 1-261643, JP-A No. 5-100430, No. 5-80518, and No. 5-
No. 80519, No. 5-80520, No. 5-665
Various matting agent technologies, latex binders and the like have been proposed in 64 etc., but they were not sufficiently satisfactory in printing durability, water retention, print image quality and scratch resistance.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate using a silver complex salt diffusion transfer method, which is excellent in various printing characteristics and particularly improved in ink transfer.

[0011]

SUMMARY OF THE INVENTION The above object of the present invention, port
Polyethylene terephthalate film or double-sided polyester
At least the undercoat layer and a silver halide emulsion layer and physical development nuclei layer on a support consisting of styrene-coated paper At a lithographic printing material by applying the silver complex diffusion transfer process <br/> Ru to Yusuke in this order, wherein
Achieved by a lithographic printing material characterized in that the weight ratio of gelatin to silver in the silver halide emulsion layer (gelatin / silver) is 0.80 or less. Further, it is preferably achieved by the center line average roughness and Ra value of the lithographic printing material being 1.2 or less.

The weight ratio of gelatin to silver of the present invention (gelatin / silver ratio) is 0.80-0.10, more preferably 0.70-0.30. When it exceeds 0.8, there is no effect on ink transfer, and when it is 0.1 or less, the printing durability tends to be remarkably reduced. Conventionally, in a lithographic printing plate using the silver complex salt diffusion transfer method, the amount of gelatin in the silver halide emulsion layer is 0.8 to 1.5 g / m ² , and the amount of silver is 0.64 to
It is generally used in the range of 0.95 g / m ² , and the gelatin / silver ratio exceeds 0.8 in all cases. The present invention has found that the gelatin / silver ratio of the silver halide emulsion layer affects the ink transfer property. That is, it was found that the ink transfer is remarkably improved by reducing the amount of gelatin relative to the amount of silver as compared with the conventional method.

The binder of the present invention is mainly gelatin, but it is possible to add synthetic or natural water-soluble polymer to gelatin, and especially 1 to 20% by weight based on the gelatin of the silver halide emulsion layer of the present invention. %, The water retention can be further improved.

When the binder of the present invention contains the above water-soluble polymer in an amount of 30% by weight or more, the water retention property is improved, but the printing durability and the ink transfer tend to be gradually deteriorated. In the present invention, the binder is mainly gelatin, and the present invention is based on the gelatin / silver ratio.

In the present invention, the center line average roughness Ra value is preferably 1.2 or less, and by combining with the gelatin / silver ratio of the present invention, the ink riding property can be effectively improved. A particularly preferable range of Ra value is 0.4 to 1.
It is 0.

In the present invention, it is a matter of course that the kind, size and amount of the matting agent play an important role in ensuring the preferable range of Ra value, and the matting agent is spherical, amorphous or tabular. A matting agent having a shape and size of about 0.1 to 5 μm can be used, and they can be used in combination. The emulsion layer may be used in an amount of 0 to 40% by weight based on gelatin, and the undercoat layer may be used in an amount of about 5 to 200% by weight based on gelatin.

The center line average roughness of the planographic printing plate is measured by a surface roughness profile measuring device, for example, Surfcom 500, manufactured by Tokyo Seimitsu Co., Ltd.
It can be measured by using B. From the roughness curve, a portion having a measurement length 1 is extracted in the direction of the center line, the center line of the extracted portion is taken as the X axis, and the longitudinal magnification direction is taken as the Y axis.
When the roughness curve is represented by y = f (x), the center line average roughness Ra value is expressed in units of micrometers, and can be calculated by the formula (1).

[0018]

[Equation 1]

The lithographic printing plate which is the object of the present invention contains gelatin, and its content may be an undercoat layer, an emulsion layer or a physical development nucleus layer. These gelatin contents can be hardened with a gelatin hardener.
Examples of the gelatin hardener include inorganic compounds such as chromium alum, aldehydes such as formalin, glyoxal, malealdehyde and glutaraldehyde, N-methylol compounds such as urea and ethyleneurea, mucochloric acid, 2,3- Aldehydes such as dihydroxy-1,4-dioxane, 2,4-dichloro-6-hydroxy-S
-A compound having an active halogen such as a triazine salt or a 2,4-dihydroxy-6-chloro-triazine salt,
Divinyl sulfone, divinyl ketone, N, N, N-triacroylhexahydrotriazine, compounds having two or more ethyleneimino groups or epoxy groups which are active three-membered rings in the molecule, and as a polymer hardener One or more of various compounds such as dialdehyde starch can be used.

The hardener can be added to all layers or to some or only one layer.
Of course, the diffusible hardener can be added to only one layer in the case of simultaneous coating of two layers. As an addition method, it may be added at the time of emulsion production or in-line at the time of coating.

Gelatin in the gelatin-containing layer of the present invention comprises a part of water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethyl cellulose, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylamide, styrene. It may be substituted with one or more hydrophilic polymers such as a maleic anhydride copolymer and a polyvinyl methyl ether-maleic anhydride copolymer. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer.

The polymeric binder of the subbing layer is generally 0.5.
It is preferably from 1 to 6 g / m ^2, more preferably from 10 to 10 g / m ² .
The undercoat layer may contain pigments such as carbon black, dyes, etc. for the purpose of preventing halation, and may contain solid powder (for example, silica particles) having an average particle size of 0.1 to 10 microns for improving printing durability. . Further, photographic additives such as developing agents can be included. The undercoat layer is disclosed in JP-A-48-
5503, 48-100203, 49-1
It may be as described in Japanese Patent No. 6507.

The silver halide emulsion layer is, for example, silver chloride,
It comprises silver bromide, silver chlorobromide, and those containing silver iodide. The silver halide crystal may contain a heavy metal salt such as a rhodium salt, an iridium salt, a palladium salt, a ruthenium salt, a nickel salt and a platinum salt, and the addition amount is from 10 ^-8 to 10 ^-3 per mol of silver halide. It is a mole. The crystal form of silver halide is not particularly limited, and may be cubic or tetradecahedral grains, or core-shell type or tabular grains. The silver halide crystal may be a monodisperse or polydisperse crystal,
The average particle size is in the range of 0.2 to 0.8 μm. One preferable example is a monodisperse or polydisperse crystal containing 70 mol% or more of silver chloride containing a rhodium salt or an iridium salt.

The silver halide emulsion can be sensitized in various ways as it is manufactured or coated. It is preferable to chemically sensitize by methods well known in the art, for example, with sodium thiosulfate, alkyl thiourea, or with a gold compound such as gold rhodanide, gold chloride, or a combination of both. The silver halide emulsions can also be sensitized or desensitized positively or negatively with dyes such as cyanines, merocyanines. There is no particular limitation on the wavelength range that can be sensitized or desensitized. Therefore, ortho sensitization, panchromatic sensitization, helium-neon laser sensitization, argon laser sensitization, LED sensitization, semiconductor laser sensitization can be performed, and UV sensitization and visible light desensitization for bright rooms. I can feel it.

The surface layer above the emulsion layer contains physical development nuclei. Physical development nuclei include fine particles of metal colloid such as silver, antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, rhodium, gold and platinum, and sulfides, polysulfides, selenides of these metals, or those. It may be a mixture or a mixed crystal. The physical development core may or may not contain a hydrophilic binder, but gelatin, starch, dialdehyde starch, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl cellulose, polystyrene sulfonic acid, vinyl imidazole and acrylamide A polymer, a hydrophilic polymer such as polyvinyl alcohol, or an oligomer thereof can be contained, and the content thereof is preferably 0.5 g / m ² or less. Further, the physical development nucleus layer may contain a developing agent such as hydroquinone, methylhydroquinone and catechol, and a known hardener such as formalin and dichloro-s-triazine.

Each of the coating layers such as the undercoat layer, the silver halide emulsion layer and the physical development nucleus layer may contain some of anionic, cationic or neutral surfactants as coating aids. , Antifoggants, matting agents, thickeners, antistatic agents and the like.

As the support for the lithographic printing plate of the present invention,
Paper or a synthetic or semi-synthetic polymer film, a metal plate such as aluminum or iron, and the like can be used as long as they can withstand lithographic printing. The surface of the support may be coated on one side or both sides with one or more polymer films or metal thin films. The surface of these supports can be surface-treated in order to improve the adhesion with the coating layer.

Particularly preferably used supports are paper having both surfaces or one surface coated with a polyolefin polymer, a polyester film, a polyester film having a hydrophilic surface, a surface-treated aluminum plate, and the like.
These supports may contain pigments for preventing halation and solid fine particles for improving surface properties. The support may also be light transmissive so that backside exposure is possible.

The developing solution used in the present invention contains an alkaline substance such as sodium hydroxide or potassium hydroxide.
Lithium hydroxide, sodium triphosphate, etc., sulfites as preservatives, silver halide solvents, such as thiosulfates,
Thiocyanates, cyclic imides, 2-mercaptobenzoic acid, amines, thickeners such as hydroxyethyl cellulose, carboxymethyl cellulose, antifoggants,
For example, potassium bromide, the compounds described in JP-A-47-26201, developers such as hydroquinones, catechol, 1-phenyl-3-pyrazolidone, development modifiers such as polyoxyalkylene compounds and onium compounds. Can be included. Further, compounds such as those described in U.S. Pat. No. 3,776,728, which improve ink transfer of the surface silver layer, can be used in the developing solution.

The surface silver layer after development of the lithographic printing plate of the present invention can be converted into ink receptivity or the receptivity can be enhanced by any known surface treatment agent. Examples of such a treatment liquid include Japanese Patent Publication No. 48-29723, US Pat.
721,559 and the like. The printing method, or the desensitizing liquid, the dampening liquid, or the like to be used may be a commonly known method.

[0031]

EXAMPLES The present invention will be explained below with reference to examples, but of course the present invention is not limited thereto.

EXAMPLE 1 A 175 micron subbed polyethylene terephthalate film was provided on one side (backing) with a matting layer containing silica particles with an average particle size of 3.5 microns (Coulter counter method), on the other side. After corona discharge machining of the surface, carbon black and silica powder having an average particle size of 3.5 μ (SY445 manufactured by Fuji Silysia Chemical Ltd.) were used.
An ortho-sensitized high with a subbing layer (gelatin 3.5 g / m ² ) containing 3, 0.6 and 0.9 g / m ² with 1-phenyl-3-pyrazolidone 0.1 g / m ² thereon. Two layers were simultaneously coated so that the sensitivity of silver chloride emulsion (containing 0.8 g / m ^{2 of} gelatin) as silver nitrate was 1.5 g / m ² (silver amount 0.95 g / m ² ).

As a hardener, 2,4-dichloro-6-
Hydroxy-s-triazine sodium was used as the undercoat layer.
0 mg / m ² and 80 mg / m ² of N-methylol ethylene urea were contained in the emulsion layer. After drying, JP-A-5
The core coating liquid described in Example 2 of 3-21602 (a polymer containing a copolymer of No. 3 acrylamide and imidazole and containing 0.5 g of hydroquinone as a developing agent)
m in a proportion of ²⁾ pullulan in JP 4-277747 a 4 mg / m ² was added to the coating, and dried to create a lithographic printing plate of Comparative.

In the lithographic printing plate of the present invention, the weight ratio of conventional emulsion layers (gelatin / gelatin /
Comparative Examples A, B, and C which are silver), the planographic printing plates D to K having the weight ratio (gelatin / silver) of the present invention (the silver amount was fixed at 0.95 g / m ² including those in Comparative Examples), and gelatin was used. Amounts were changed) and the lithographic printing plates are summarized in Table 1.

Immediately after the production of these 11 kinds of lithographic printing plates and after storing them for 5 days under the conditions of 50 ° C. and 80% relative humidity, image exposure was carried out by a plate making camera having an image reversing mechanism, and the following silver complex salt 1 at 30 ° C with diffusion transfer developer
Development processing was performed for a minute.

<Transfer developer> 700 ml of water 20 g of potassium hydroxide 50 g of anhydrous sodium sulfite 50 g 2-mercaptobenzoic acid 1.5 g 2-methylaminoethanol 15 g Water is added to make 1 liter. After the development treatment, the original plate is passed between two squeezing rollers to remove excess developer, and immediately treated with a neutralizing solution having the following composition at 25 ° C. for 20 seconds. Dried in.

<Neutralization liquid> Water 600 ml Citric acid 10 g Sodium citrate 35 g Colloidal silica (20% liquid) 5 ml Ethylene glycol 5 ml Water is added to make 1 liter. The lithographic printing plate prepared by the above operation was mounted on an offset printing machine, and the following desensitizing liquid was applied all over the plate surface,
Printing was performed using the following dampening liquid.

[0038]   <Desensitizing liquid>     600 ml of water     Isopropyl alcohol 400 ml     Ethylene glycol 50g     3-Mercapto-4-acetamido-5-n-heptyl-1,2,4-tri Azole 1g

<Moisturizing liquid> o-phosphoric acid 10 g Nickel nitrate 5g Sodium nitrite 5g Ethylene glycol 100g Colloidal silica (20% liquid) 28g Add water to make 2 liters.

As for the printing durability, RYOBI 3200CD (trademark of RYOBI KK offset printing machine) is used, and non-image area scumming and image drop due to lack of silver image area occur and printing cannot be performed. The number of printed sheets at that time was judged according to the following evaluation criteria. The ink is ABdick3-1012.
It was used. ○ 10,000 to 20,000 sheets Δ 5,000 to 10,000 sheets × 2,000 to 5,000 sheets The printing results are shown in Table 2.

The ink-carrying was evaluated under the condition that the printing durability was evaluated, by the number of the inks completely covered without using the desensitizing liquid. It should be noted that the ink transfer was worse immediately after production, and was evaluated with the plate immediately after production.

[0042]

[Table 1]

[0043]

[Table 2]

From the above results, it was confirmed that the weight ratio (gelatin / silver) of the present invention was excellent in ink transfer.
Furthermore, it was confirmed that the water retention and the image quality were excellent by limiting the surface roughness, but it was confirmed that the ink transfer was further improved.

Example 2 Example 1 except that the 175 micron thick polyester base used in Example 1 was replaced with 135 g / m ² double sided polyethylene coated paper (matte side, Ra = 1.0). Table 3 shows the results of the test evaluation performed in the same manner as in.

[0046]

[Table 3]

It was confirmed that the polyethylene coated paper was also excellent in ink-carrying due to the weight ratio (gelatin / silver) of the present invention. Furthermore, it was confirmed that the water retention and the image quality were excellent by limiting the surface roughness, but it was confirmed that the ink transfer was further improved.

[0048]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a lithographic printing plate which is excellent in ink-carrying properties of the lithographic printing plate to which the silver complex salt diffusion transfer method is applied.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03F 7/07 G03F 7/00 503 G03C 8/06 501 G03C 8/08 505

Claims (2)

(57) [Claims] 1. A polyethylene terephthalate film
Rui At a lithographic printing material is applied at least the undercoat layer, a silver complex diffusion transfer process comprising a silver halide emulsion layer and physical development nuclei layer in this order on a support made of polyethylene double coated paper, the silver halide emulsion A lithographic printing material characterized in that the weight ratio of gelatin to silver in the layer (gelatin / silver) is 0.80 or less. 2. The planographic printing material according to claim 1, wherein the center line average roughness and Ra value are 1.2 or less.
Lithographic printing material.