JPS6116058B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developer composition for lithographic printing plates.

Photocrosslinkable photosensitive polymer compositions have already been widely put into practical use as photoetching resists. This type of photosensitive polymer and polymer composition surpasses the diazo photosensitive materials that have been put to practical use as lithographic printing plates and the like in terms of performance such as sensitivity, storage stability, image strength, and oil sensitivity. Therefore, photocrosslinkable photosensitive polymers have recently come to be widely used in lithographic printing plates. Photosensitive polymers crosslink and harden when exposed to actinic radiation, making them relatively insoluble in solvents compared to unexposed polymers. In this way, printing plates can be created photographically by utilizing the difference in properties between exposed and non-exposed areas. That is, by coating a photosensitive polymer in a layer on a lithographic printing plate support together with other additives such as sensitizers and colorants, and exposing the plate having this coating layer to radiation in an image pattern,
A soluble region and an insoluble region are created in the photosensitive layer. The plate is then developed to remove the unexposed, uncured soluble polymer, such as by treatment with a developing solvent or solution that dissolves the unexposed polymer. Further, the developer containing the unexposed, non-curable soluble polymer remaining on the plate surface is removed from the plate surface by washing with water or a water-based desensitizing agent, thereby cleaning the printing plate. In this way, an image is formed on the printing plate with hydrophilic areas that do not accept printing ink and lipophilic areas that accept printing ink, and is used for printing operations.

Conventionally, various developers have been known for photosensitive polymers, such as compositions containing γ-butyrolactone and acids. However, conventional developers
When it is new, the lithographic printing plate can be developed well, but it is not satisfactory in terms of lifespan for repeated use, stability of the development effect against changes in development conditions such as development time, and storage stability of the developer. There are cases. In addition, conventional developers have poor affinity with water, and residual developer cannot be efficiently removed from the plate surface by washing with water after development or treatment with a water-based desensitizing agent, resulting in background smudges and uneven images. There is.

The present inventors have made extensive studies to provide a developer composition for photosensitive polymers that does not have such problems.

That is, the objects of the present invention are as follows: (1) A novel developer composition for lithographic printing plates having a colored coating layer of a photosensitive polymer, which has a stable development effect against changes in development conditions. (2) To provide a developer composition that has a slow rate of fatigue due to cyclical reuse, has excellent storage stability, and can be stably developed over a long period of time. (3) After development To provide a developer composition that can be efficiently removed from a plate surface during subsequent washing with water or treatment with an aqueous desensitizing agent. To provide a developer composition that does not cause uneven development and does not cause contamination or scum, not only for new products but also for old products. It is an object of the present invention to provide a developer composition capable of quickly removing coloring agents, ie, pigments or dyes, from a photosensitive layer that remain in non-image areas and cause background smudges.

And these purposes include the general formula () in the main chain (In the formula, X and Y represent a hydrogen atom, a halogen atom, a cyano group, or a nitro group, and n represents a number of 1 or 2.) For lithographic printing plates having a coating layer of a photosensitive polymer having a group represented by This is achieved by containing tetrahydrofurfuryl alcohol in the developer composition.

The present invention will be described in detail below. One component constituting the developer composition of the present invention is tetrahydrofurfuryl alcohol. Solvents that can be used as developer compositions are based on their workability and safety.
In general, those with low volatility are preferred, with a boiling point of 150℃
The above are preferred. Among solvents having such physical properties, tetrahydrofurfuryl alcohol has relatively good solubility in the composition of a photosensitive polymer having a group represented by the general formula () in the non-exposed portion, and The exposed polymer composition does not swell so that the pigment is not eluted from the exposed insolubilized region, and it has extremely good affinity for water.

The content of tetrahydrofurfuryl alcohol usually ranges from 5 to 90% by weight, preferably from 30 to 60% by weight in the developer composition. In addition, the developer composition can contain a good solvent and a poor solvent for the polymer composition in the non-exposed area according to a conventional method, as required, so that the polymer composition in the non-exposed area It has a good solvent action and can maintain a good developing effect over a long period of time, and also does not substantially swell the polymer composition in the exposed area and does not damage it. Can be adjusted to a range of dissolving power. Tetrahydrofurfuryl alcohol has the ability to sufficiently mix a good solvent with a poor solvent or water, so it is easy to balance the performance of the developer over a wide range, and it is also easy to wash the developer with water or use a water-based desensitizing agent. It seems that it can be removed by

Ethylene glycol monophenyl ether is suitable as a good solvent, and its content is preferably
It is 30-60% by weight.

Other relatively high-boiling solvents that do not swell the exposed polymer composition, such as benzyl alcohol, α-methylbenzyl alcohol, and ethylene glycol monobenzyl ether, can also be used as well as ethylene glycol monophenyl ether.

Examples of poor solvents include diethylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; triethylene glycol monoalkyl ethers such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether; diethylene glycol Diethylene glycol monoalkyl ether acetates such as monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate; triethylene glycol monoalkyl ether acetates such as triethylene glycol monomethyl ether acetate, triethylene glycol monoethyl ether acetate; ethylene glycol monomethyl ether acetate,
Examples include ethylene glycol monoalkyl ether acetates such as ethylene glycol monoethyl ether acetate and ethylene glycol monobutyl ether acetate; and ethylene glycol monoalkyl ethers such as ethylene glycol monopropyl ether and ethylene glycol monoisopropyl ether.

The content of the poor solvent in the developer composition is effectively in the range of 1 to 50% by weight, preferably in the range of 5 to 30% by weight.

An effective amount of water in the developer composition is 0.1 to 10% by weight. Water may be used when adding the acid component described below.

The developer composition of the present invention may contain an acid component in order to prevent scum and stains from forming in non-image areas of the lithographic printing plate. Examples of acids include mineral acids such as phosphoric acid, sulfuric acid, and hydrochloric acid; organic carboxylic acids such as acetic acid, lactic acid, glycolic acid, and α-pentenoic acid; and organic sulfonic acids such as benzenesulfonic acid and paratoluenesulfonic acid. can be mentioned.
However, since hydrochloric acid tends to corrode the metal materials of automatic processors, it is preferable to use it in as little amount as possible. A particularly preferred acid is phosphoric acid. Usually, the amount of acid added to the developer composition ranges from 0.1 to 10% by weight based on the total amount of the developer composition. Since acidic development is preferred, the amount of acid added should be adjusted such that the developer composition is acidic in relation to the other components present, preferably with a pH of about 1-6.

In addition to the above-mentioned components, the developer composition has properties that allow the developer supplied to the lithographic printing plate to spread well over the plate surface and properties that prevent separation of the polymer and pigment that are removed from non-image areas. Preferably, one or more wetting agents or surfactants are included in conventional manner for application. Examples of these wetting agents or surfactants include polyhydric alcohols such as glycerol and diethylene glycol; n-hexanol, n-hexanol, and n-hexanol;
- Phosphate esters of alkanols such as decanol; polyethers such as polyoxyethylene octyl phenyl ether and polyoxyethylene oleyl ether; and organic acid esters such as sodium dialkylsulfosuccinate.

In addition, one or more lipophilicity improvers such as methyl abietate, ethyl abietate, etc. may be added to the exposed and hardened image areas of the lithographic printing plate to improve ink receptivity in accordance with conventional methods. It is even more preferable to include it.

In addition to the above-mentioned components, the developer composition has the following properties: to effectively remove the photosensitive layer composition from the non-image areas, to prevent contamination and scum in the non-image areas, or to remove the polymer composition from the image areas. It is further preferable to include a small amount of a basic amine such as triethanolamine or other salts as other auxiliary agents for preventing swelling.

The developer composition of the present invention is effective for lithographic printing plates having a coating layer made of a photosensitive polymer having a group represented by the general formula () in the main chain, such as polyester, polycarbonate, polysulfonate, or the like. The photosensitive polymer is typically a polyester-based polymer, and such a polyester has, for example, the general formula () in its main chain.
It can be easily produced by polycondensing a polyhydric carboxylic acid or an ester-forming derivative thereof to form a group represented by the above with a polyhydric alcohol according to a conventional method. Examples of the polyhydric carboxylic acids mentioned above include P-phenylene diacrylic acid, P-carboxycinnamic acid, and bis(P-carboxybenzal).
Examples include cyclohexane, bis(P-carboxybenzal)cyclopentanone, bis(P-carboxycinnamoyl)benzene, P,P'-chalconedicarboxylic acid, fumaric acid, and maleic acid. Among these, P-phenylene diacrylic acid is particularly preferred. Further, in addition to such polyvalent carboxylic acids, polyvalent carboxylic acids such as succinic acid, adipic acid, and terephthalic acid can also be used. In addition, polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, hydrogenated bisphenol A, and hydrogenated bisphenol A. Examples include bisphenol F, bis(β-hydroxyethoxy)cyclohexane, P,P'-dihydroxychalcone, and these may be used alone or in a mixture of two or more.

Lithographic printing plates are usually prepared by coating the photosensitive polymer in a layer on a support together with other additives such as sensitizers and colorants such as phthalocyanine pigments in a conventional manner. A lithographic printing plate using a phthalocyanine pigment has a colored coating layer.

Supports for printing plates include aluminum, mechanically, electrochemically, or chemically surface-treated metal plates such as aluminum, copper, and zinc;
Examples include paper, polymer-coated paper, and synthetic resin.

Development using the developer composition of the present invention can be carried out according to a conventional method. For example, this can be carried out by supplying the developer of the present invention to the surface of an imagewise exposed lithographic printing plate and removing the unexposed polymer composition from the surface of the support. However, at this time, applying a gentle mechanical action such as wiping the surface is effective in removing the polymer composition from the non-image areas of the lithographic printing plate.

After the above development treatment, the lithographic printing plate is subsequently washed with water or treated with an aqueous desensitizing agent in order to remove the developer remaining on the plate surface.

Since the developer composition of the present invention contains tetrahydrofurfuryl alcohol, it has good affinity with water, and residual developer can be efficiently removed from the plate surface by washing with water or treatment with an aqueous desensitizing agent.

Water-based desensitizing agents include, for example, water-soluble natural polymers such as gum arabic, mesquite gum, dextrin, sodium alginate, and carboxyl cellulose; polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, or maleic anhydride/vinyl ether copolymer. Examples include aqueous solutions containing 5 to 30% by weight of water-soluble synthetic polymers such as polymers. At that time, a surfactant and an acid component such as phosphoric acid may be used in combination, if necessary.

Thus, by using the developer composition of the present invention, a lithographic printing plate that gives a good image without scumming or image unevenness can be obtained.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 1 A 4% by weight cyclohexanone solution of a photosensitive polyester made by condensation of 1.0 mol of P-phenylene diacrylic acid, 0.35 mol of hydrogenated bisphenol A, and 0.65 mol of triethylene glycol was added with 1,
A photosensitive liquid was prepared by adding 10% by weight of 8-dimethoxyanthraquinone to the polyester and 15% by weight of phthalocyanine pigment to the polyester. This photosensitive solution is applied to an electrolytically treated aluminum plate from 1.0 to
It was applied to a film thickness of 1.2μ. The lithographic printing plate thus obtained was dried, exposed through a negative film, and developed with a developer composition having the following composition. The development process was carried out using an automatic developing machine having a rubbing mechanism using a rotating brush roller.

Ethylene glycol monophenyl ether...50% by weight Tetrahydrofurfuryl alcohol...40 Diethylene glycol monomethyl ether...5% by weight 85% phosphoric acid...3 Water...2 Processing speed of automatic processor during development processing That is, although the transport speed of the lithographic printing plate was varied from 0.5 m/min to 2 m/min, no change was observed in the image on the printing plate, for example, the gray scale. Moreover,
This printing plate had no substantial swelling or damage to the exposed and cured image area polymer composition, and no pigment was observed in the non-image areas. When printed using this printing plate, good printed matter was obtained without staining in the non-image area.

Comparative Example 1 The lithographic printing plate described in Example 1 was developed in the same manner using a developer composition having the following composition.

γ-Butyrolactone...83% by weight Glycerin...5 γ-oxybutyric acid monoglyceride...3 γ-oxybutyric acid...3 P-toluenesulfonic acid...2 Water...4 This lithographic printing plate gives good images, No contamination was observed in non-image areas. However, when the conveyance speed of the planographic printing plate in the automatic processor was changed from 0.5 m/min to 2 m/min, the grayscale image formed on the printing plate changed by a maximum of one step.

Example 2 The lithographic printing plate described in Example 1 was developed by repeatedly using the developer having the composition of Example 1. That is, 200 m ² of the above-mentioned unexposed lithographic printing plate was developed in an automatic developing machine, but no precipitated components were observed in the developer, and the printing plate was developed cleanly without being contaminated. Further, when the above-described image-exposed lithographic printing plate was developed using this developer, the printing plate was free from any contamination and a good image was formed. When printed using this printing plate, good printed matter was obtained without staining in the non-image area.

Comparative Example 2 A developing solution with the following composition was repeatedly used, and Example 1
The lithographic printing plate described above was developed.

Ethylene glycol monophenyl ether...50% by weight Diethylene glycol monoethyl ether acetate...20% by weight Diethylene glycol monomethyl ether...20% by weight 85% phosphoric acid...5 〃 Water... 5 〃 The above-mentioned imagewise exposed with the developer of the present invention When the lithographic printing plate was developed, a printing plate with a good image was obtained as in Example 1. In addition, when the unexposed lithographic printing plate mentioned above was developed in an automatic developing machine in an area ^of 50 m ² , precipitates were observed in the developer. When the lithographic printing plate was subjected to development treatment, the printing plate was contaminated by precipitates in the developer, and a clean printing plate could not be obtained.

Example 3 In the development process using the developer of Example 1, the conditions of the squeegee roller at the end of the developing section of an automatic processor, that is, the conditions for mechanically squeezing out the developer, were changed to improve the subsequent water washing or When processing with a water-based desensitizing agent, even if the developing solution containing the polymer composition in the unexposed area was not sufficiently removed mechanically, the developing solution was removed by washing with water or the water-based desensitizing agent. It was removed efficiently and a good image was formed on the printing plate.

Comparative Example 3 When the developer of Comparative Example 2 was used and the same study as in Example 3 was carried out, it was found that due to changes in the conditions of the squeegee roller at the end of the developing section of an automatic processor, washing with water or using a water-based desensitizer Differences were observed in the treatment effects. In other words, if the developer is not sufficiently removed mechanically and remains on the printing plate, then if it is washed with water or treated with an aqueous solution containing 10% by weight of dextrin and 1% by weight of gum arabic, the developer will not be removed efficiently. However, the image on the printing plate was not very clear.

Claims (1)

[Claims] 1 General formula () in the main chain (In the formula, X and Y represent a hydrogen atom, a halogen atom, a cyano group, or a nitro group, and n represents a number of 1 or 2.) For planographic printing plates having a coating layer of a photosensitive polymer having a group represented by A developer composition for a lithographic printing plate, characterized in that the developer composition contains tetrahydrofurfuryl alcohol. 2. The developer composition for a lithographic printing plate according to claim 1, wherein the developer composition contains tetrahydrofurfuryl alcohol and ethylene glycol monophenyl ether.