JPH07319171A - Washing water for planographic printing plate and plate making method of planographic printing plate - Google Patents

Abstract

PURPOSE:To prevent fault of inking in the initial stage of the process even when recycled water is used in a washing process with water after development or a small amt. of fresh water is used, by incorporating at least one kind of compd. selected from specified compds. as an additive. CONSTITUTION:This washing water for planographic printing contains at least one kind of compd. selected from compds. expressed by formulae I, II as an additive. In formula, R is a hydrogen atom, NH4, or alkali metal such as Li, K, and Na. A single material or combination of two or more compds. may be used for the washing water for a planographic printing plate. The amt. of the compd. added to the washing water is 0.001-5wt.% to the washing water, and preferably 0.001-1wt., and more preferably 0.001-0.5wt.%. If the amt. is less than 0.001wt.%, the effect to improve the buildup property is not enough. If the amt. is >=5wt.%, it is disadvantageous for the running cost and bad influences are given to the physical property of the washing water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to rinsing water used for making a lithographic printing plate and a method for making a photosensitive lithographic printing plate using the rinsing water. In particular, the ink receptivity at the start of printing is improved. The present invention relates to washing water and a method for making a photosensitive lithographic printing plate using the same.

[0002]

2. Description of the Related Art Conventionally, a photosensitive lithographic printing plate is generally processed through processing steps such as a developing step, a water washing step, and a step of providing a hydrophilic plate surface protective layer. Generally, in order to prevent the developing solution and the components of the photosensitive layer eluted into the developing solution from remaining on the developed printing plate, a washing treatment is carried out after the development. In an automatic developing device, it is usual to circulate and repeatedly use washing water for the purpose of saving water, etc., but in a lithographic printing plate that has been subjected to washing treatment with repeatedly used washing water, the printing ink is printed on the image area. There was a case where a so-called defective inking, which is difficult to attach, occurred. As a countermeasure for this poor meat filling,
There is also a method of rinsing with fresh water for each lithographic printing plate, but when a large amount of rinsing water was used, it was effective as a measure against inking defects, but the amount of wastewater increased drastically, which is not preferable. In addition, washing with a small amount of fresh water was not a complete countermeasure for defective inking.

[0003]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to start at the start even if repeated washing water is used in the washing step after the development processing of the photosensitive lithographic printing plate or a small amount of fresh water is used. Another object of the present invention is to provide a rinsing water that does not cause the ink inking defect and a method for making a lithographic printing plate using the rinsing water.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the inventors of the present invention found a rinsing water capable of effectively preventing defective inking, and completed the present invention. However, the objects of the present invention can be achieved by the configurations described in (1) to (5) below. (1) A rinsing water for a lithographic printing plate comprising at least one compound selected from compounds represented by the following general formulas [I] and [II] as an additive.

[0005]

[Chemical 2]

(2) A rinsing water for a lithographic printing plate containing at least one compound selected from the following compound group (a) as an additive. [Compound Group (a)] 1,3,5-Trishydroxyethylhexahydro-S-triazine, 1,3,5-trishydroxymethylhexahydro-S-triazine, 1-
(3-chloroallyl) -3,5,7-triaza-1-azonia adamantan chloride, 2-phenoxyethanol, α-bromocinnamaldehyde, 1,2-benzisothiazoline, methyl 2-benzimidazolylcarbamate, 3-methyl- 4-isopropylphenol, N-
Sodium methyldithiocarbamate, 5-methyl-
1,2,4-triazolo [3.4-b] benzothiazole, N-lauroyl-sarcosine sodium, N-lauroyl-N-methyl-β-aminopropionate sodium, resorcinol, pyrogallol, resorcinol monoacetate, sodium alginate, Disodium ethylenebisdithiocarbamate, 10,10'-oxybisphenoxaarsine, cresol, 2,5-dichloro-
4-bromophenol, 2- (4'-thiazolyl) -benzimidazole, 2,4,4'-trichloro-2'-
Hydroxydiphenyl ether and salts thereof. (3) The rinsing water for lithographic printing plates as described in (1) or (2) above, wherein the amount of the additive added is 0.001 to 5% by weight of rinsing water. (4) In the plate-making method in which the photosensitive lithographic printing plate is imagewise exposed, then developed, washed with water, and a hydrophilic plate surface protective layer is provided on the printing plate, the rinsing water at the time of rinsing is represented by the general formula [I] or [II]. ] Or a compound represented by the above-mentioned compound group (a) is contained as an additive. (5) The rinsing water for a lithographic printing plate as described in any of (1) to (3) above, wherein the rinsing water further contains a chelating agent.

The present invention will be described in detail below. General formulas [I] and [II] contained in the washing water of the lithographic printing plate of the present invention
The compound of 1) or the compound of the compound group (a) is effective for improving the ink receptivity at the start. The mechanism is not clear, but it is considered that there is an action of preventing adsorption to the image area of the hydrophilic component of the developer in washing water. Typical specific examples represented by the general formulas [I] and [II] used in the present invention are shown below, but the present invention is not limited thereto. (Exemplified compound)

[0008]

[Chemical 3]

[0009]

[Chemical 4]

Among these compounds, [I] -2, [I]
-3, [I] -4, [II] -2, [II] -3 and [I]
I] -4 is preferable because it easily dissolves in water. In the present invention, the compounds represented by the following general formula [I] or [II] contained in the washing water of the lithographic printing plate can be used alone or in combination of two or more kinds. The amount of these compounds added to the wash water is 0.001 to 5% by weight based on the wash water.
And more preferably 0.001 to 1% by weight, and particularly preferably 0.001 to 0.5% by weight. If the addition amount is less than 0.001% by weight, the effect of improving the inking property, which is the object of the present invention, is small, while if it is 5% by weight or more, the effect of improving the inking property reaches an equilibrium state. Addition is disadvantageous in terms of running cost and also has an adverse effect on the physical properties of washing water.

Instead of the compounds of the general formulas [I] and [II] contained in the washing water of the present invention, the compound group (a) (1,3,5-trishydroxyethylhexahydro-S) of the present invention is used. -Triazine, 1,3,5-trishydroxymethylhexahydro-S-triazine, 1- (3-
(Chloroallyl) -3,5,7-triaza-1-azoniaadamantan chloride, 2-phenoxyethanol, α
-Bromcinnamaldehyde, 1,2-benzisothiazoline, methyl 2-benzimidazolylcarbamate,
3-methyl-4-isopropylphenol, sodium N-methyldithiocarbamate, 5-methyl-1,2,
4-triazolo [3.4-b] benzothiazole, N-
Lauroyl-sarcosine sodium, N-lauroyl-
Sodium N-methyl-β-aminopropionate, resorcinol, pyrogallol, resorcinol monoacetate, sodium alginate, disodium ethylenebisdithiocarbamate 10,10'-oxybisphenoxaarsine, cresol, 2,5-dichloro-4- Bromphenol, 2- (4'-thiazolyl) -benzimidazole, 2,4,4'-trichloro-2'-hydroxydiphenyl ether and salts thereof, which are stable in a strong alkali, are used. Similar to the case of containing the compounds of the general formulas [I] and [II], it is effective in improving the ink receptivity at the start, and the mechanism is not clear, but the hydrophilic component of the developer in the wash water is not clear. It seems to have a function of preventing adsorption to the image area. The compound group (a) of the present invention may be used alone or in combination of two or more, and among the compounds of the constitution (5) of the present invention, 1,3,5-trishydroxyethylhexahydro-S-triazine Is preferably used. The amount of the compound group (a) of the present invention added to the washing water is the same as in the case of the compounds of the general formulas [I] and [II]. The compounds of the above formulas [I] and [II] and the compound group (a) of the present invention
There are some compounds that are insoluble in water, but it is possible to disperse them uniformly in the rinsing water in a suitable manner, for example, by dissolving them in a glycol solvent or forming a suspension in which they are dispersed in water. it can.

The washing water of the present invention has the general formulas [I] and [I]
In addition to the compound I], it is preferable to contain a chelating agent. The chelating agent is effective for increasing the stability of the compounds [I] and [II] in the wash water. Examples of the chelating agent used in the present invention include EDTA (ethylenediaminetetraacetic acid) and its salts, NTA (nitrilotriacetic acid) and its salts, HEDTA (hydroxyethylethylenediaminetriacetic acid) and its salts, DPTA (diethylenetriaminepentaacetic acid) and Its salts, TTHA (triethylenetetramine hexaacetic acid) and its salts, HIDA (hydroxyethyliminodiacetic acid) and its salts, DHEG (dihydroxyethylglycine) and its salts, CyDTA (cyclohexanediaminetetraacetic acid) and its salts, EHPG [ Ethylene bis (hydroxyphenylglycine)] and salts thereof, H
EDP (1-hydroxyethylidene-1,1-diphosphonic acid) and its salts, ATMP [aminotri (methylenephosphonic acid)] and its salts, polyelectrolytes such as sodium polyacrylate, sodium polymethacrylate, sodium polymaleate, Examples thereof include sodium polyitaconate and copolymers thereof, but are not limited thereto as long as they exhibit a chelating power for metal ions. The chelating agent in the present invention is 1
One kind or a combination of two or more kinds can be used. The preferred amount of chelating agent used is 0.0001 with respect to the washing water.
To 0.01% by weight, and more preferably 0.001 to
0.005% by weight, particularly preferably 0.002-0.0
It is 03% by weight. The amount of chelating agent used is 0.0001
To 0.01% by weight, the compounds [I], [I
The concentration is suitable for chelating a metal ion that reduces the stability of [I], which is preferable. If it is less than 0.0001% by weight, metal ions that cannot be chelated remain, and
If the amount exceeds 5% by weight, the amount of residual metal ions becomes small, and if the amount is more than that, the running cost becomes disadvantageous. The additive of the present invention (formula [I], [I
The compound of [I], which represents the compound group (a)), may be added to the washing water in the form of powder or tablets, but it can be added to the washing water in the form of a solution previously dissolved in water or a suitable organic solvent. The solution type is preferred in consideration of easiness of mixing with washing water. In this case, the solution type compound preferably contains the compound of the general formula [I] or [II] or the compound of the compound group (a) in an amount of 1% by weight or more, more preferably 5% by weight or more.
In the washing water of the present invention, the compounds of the general formulas [I] and [II] and the compounds of the compound group (a) can be used in combination.

The washing water to which the additive of the present invention is added is a positive or negative photosensitive lithographic printing plate (hereinafter abbreviated as PS plate).
It can be used in the water washing step during plate making. The positive PS plate to which the present invention can be applied is, for example, Japanese Patent Publication No.
JP-A-62-14652, 63-226641
A PS plate as described in detail in JP-A No. 2-8663 and JP-A No. 2-8663 is preferably used. Negative PS plates include, for example, those using a diazo compound as a photosensitive material, those using a photocrosslinkable compound, and those using a photopolymerizable compound. As the diazo compound, conventionally known compounds can be appropriately used. Examples thereof include diazo resin inorganic salts, which are organic solvent-soluble reaction products of a condensate of p-diazodiphenylamine and formaldehyde or acetaldehyde, and hexafluorophosphate and tetrafluoroborate, and US As described in Japanese Patent No. 3,300,309, the condensate and sulfonic acids such as paratoluenesulfonic acid or a salt thereof, phosphinic acids such as benzenephosphinic acid or a salt thereof, and JP-B-49-48001. Publication, JP-A-2-2965
A co-condensation diazo resin with an aromatic compound described in JP-A-0 is also preferably used. Examples of the photocrosslinkable compound include those having a maleimide group in the side chain described in JP-A-2-236552, and examples of the photopolymerizable composition are described in JP-A-63-257749. I can give you something. The PS plate is exposed through a transparent original image by a light source rich in actinic rays such as a carbon arc lamp, a mercury lamp, a metal halide lamp, and a tungsten lamp, and then developed in a developing process by a wet process. For the plate-making method of the present invention, a developer as described in JP-A-5-2271 or Japanese Patent Application No. 5-71589 is preferably used. As a method for developing the PS plate imagewise exposed with the above-mentioned developing solution, various conventionally known methods can be used. Specifically, a method of immersing the image-exposed PS plate in a developer, a method of spraying the developer from a large number of nozzles onto the photosensitive layer of the PS plate, and a sponge wetted with the developer Examples thereof include a method of wiping the photosensitive layer and a method of roller-coating a developing solution on the surface of the photosensitive layer of the PS plate. Further, after the developing solution is applied to the photosensitive layer of the PS plate in this way, the surface of the photosensitive layer can be lightly rubbed with a brush or the like.

The lithographic printing plate obtained by the above-mentioned development treatment is washed with water in the subsequent washing treatment step, but is squeezed so that the amount of the developing solution on the plate surface is reduced prior to washing with water. Is desirable. Examples of the squeezing method include a method of scraping off the developing solution on the plate surface with an air knife, a method of scraping off the developing solution on the plate surface by bringing an elastic plastic material having a smooth surface into sliding contact with the plate surface, and a method such as rubber. Examples include a method of removing the developer on the plate surface by nip pressure by passing a plate between an elastic roller pair in which an elastic member is coated on the roller surface, but when using an automatic developing machine, a method of using the elastic roller pair is used. preferable.

The rinsing water in the subsequent lithographic printing plate washing step may be repeatedly circulated, or fresh water may be used for each lithographic printing plate, and a part of the circulated rinsing water may be used. May be used while being supplemented with fresh water at any time. The method of adding the additive of the present invention to the washing water when the washing water is repeatedly circulated is described in, for example, a washing section tank of an automatic processor as described in JP-A-2-2569. A predetermined amount of the additive of the present invention, which is measured by an appropriate method, or a predetermined amount of washing water and the additive of the present invention, which is measured by an appropriate method, are mixed, and then a water washing section tank The method of charging to When the wash water is repeatedly circulated as described above, in order to reduce the mixing of the developer component in the rinsing water used for circulation to the desensitizing (gumming) treatment liquid used in the step after the wash. In addition, fresh water may be added to the flush tank. In such a case, it goes without saying that the additive of the present invention is added to fresh water, but the addition method is to add a predetermined amount of fresh water to a storage tank of fresh water and add the additive of the present invention measured by an appropriate method. Examples thereof include a method of adding an agent, a method of mixing a predetermined amount of washing water with an additive of the present invention measured by an appropriate method, and then charging the mixture in a storage tank. Alternatively, if the storage tank is of a type in which the water level is automatically kept constant by floater control, a method of adding a fixed amount of the present additive to the storage tank at fixed intervals is also effective.

Further, when the washing water used is fresh water for each plate of the planographic printing plate, the method of adding the additive of the present invention to the washing water is described in, for example, JP-A-2-3065 or A method of adding a predetermined amount of fresh water to a storage tank for washing water of an automatic processor as described in Japanese Patent Application No. 5-73672, and adding the additive of the present invention to the storage tank, or Examples include a method in which a predetermined amount of washing water and the additive of the present invention measured by an appropriate method are mixed in advance and then charged into a storage tank. Alternatively, if the storage tank is of a type in which the water level is automatically kept constant by floater control, a method of adding a fixed amount of the present additive to the storage tank at fixed intervals is also effective. As a method of rinsing the lithographic printing plate with the rinsing water to which the additive of the present invention has been added, for example, a method of immersing the lithographic printing plate in a tank filled with rinsing water, and preferably taking out by stirring,
There is a method of supplying washing water onto the plate through a pipe or the like having a single or a plurality of narrow holes on the planographic printing plate. The latter method is advantageous when using an automatic processor. In this case, it is preferable that an appropriate amount of washing water is supplied in a timely manner as it passes through the washing section of the PS plate. Preferred amount of washing water is 5~300cc / m ^2, but more preferably 10~100cc / m ^2, particularly preferably 20~80cc / m ²
Is. If it is less than 5 cc / m ² , washing of the lithographic printing plate becomes insufficient, and if it exceeds 300 cc / m ² , the amount of waste water increases, which is not preferable. The lithographic printing plate washed with water is preferably squeezed so that the washing water remaining on the plate surface is reduced, and the squeezing method may be the method of squeezing the developing solution, but an automatic developing machine is used. In this case, a method using a pair of elastic rollers is preferable.

Further, in the plate making process of the lithographic printing plate, various treatment steps can be provided as needed after the washing step. Examples of the step following the water washing step mainly include desensitizing (gumming) treatment. Examples of the desensitizing treatment liquid applicable to the present invention include, for example, JP-A-2-11.
There are desensitizing treatment liquids as described in detail in Japanese Patent No. 3997 and Japanese Patent Publication No. 5-19920. Further, as another step following the water washing step, treatment with an aqueous solution containing a surfactant can be mentioned. Examples of the aqueous solution containing a surfactant applicable to the present invention include, for example, JP-A-63-16.
9645, 63-169646, 63-16964
7, 63-172270, there is an aqueous solution containing a surfactant as described in detail. In addition to these, steps such as developing ink piling and correction of the image area are carried out, but the additive of the present invention, regardless of the type of step after washing with water,
It is possible to use. The washing water to which the additive of the present invention has been added is used not only as the washing water after the development of the lithographic printing plate described above, but also as the washing water of the automatic washing machine after erasing, and also the toner image formed by the electrostatic photography method. It is also suitably used as washing water after the step of eluting the material for forming an image by eluting the lower organic resin layer on the mask. Further, it is also used as a silver halide diffusion transfer method or as washing water after development of a light-sensitive material using silver as a polymerization initiator.

[0018]

The present invention will be described in detail with reference to the following examples. Example 1 A [SiO ₂ ] / [M ₂ O] ratio of 1.2 and an aqueous potassium silicate solution containing 1.5 wt% of SiO _{2 were used.}
22 liters of a developer containing 0.04% by weight of N, N-dihydroxyethyl betaine amphoteric surfactant was prepared, and PS processor PS900NP manufactured by Fuji Photo Film Co., Ltd.
(Automatic processor of the type where wash water is repeatedly circulated)
And kept at 30 ° C. Furthermore, tap water 7
7 g of compound [I] -4 and 4N of EDTA per liter
0.14 g of salt a was added, and an aqueous solution with good stirring was charged. In addition, PS from Fuji Photo Film Co., Ltd.
-Plate finishing gum FP-2W 7 liters of desensitizing liquid consisting of 50 parts by weight and 50 parts by weight of tap water were charged. Next, an aluminum plate having a thickness of 0.3 mm was grained on its surface using a nylon brush and an aqueous suspension of 400 mesh pumice, and then washed thoroughly with water. 1
It was immersed in 0% sodium hydroxide at 70 ° C. for 60 seconds for etching, washed with running water, neutralized with 20% HNO ₃ and washed with water. This was subjected to electrolytic surface-roughening treatment in an aqueous 1% nitric acid solution under the condition of V _A = 12.7 V in an aqueous 1% nitric acid solution at an anode-time electric quantity of 160 coulomb / dm ² . The surface roughness was measured and found to be 0.6 μ (Ra indication). Then, it is immersed in 30% H ₂ SO ₄ aqueous solution and desmutted at 55 ° C. for 2 minutes, and then 20% H ₂
A cathode was placed on a grained surface in an SO ₄ aqueous solution and anodized to a thickness of 2.7 g / m ² at a current density of 2 A / dm ² to prepare a substrate.

The back surface of the substrate thus treated was coated with the sol-gel reaction solution described below with a bar coater and dried at 100 ° C. for 1 minute to form a back coat layer having a coating amount of 50 mg / m ² after drying. The provided substrate was produced. Sol-gel reaction solution Tetraethyl silicate 50 parts by weight Water 21.6 parts by weight Methanol 10.8 parts by weight Nitric acid 0.05 parts by weight When the above components were mixed and stirred, heat was generated in about 5 minutes. After reacting for 10 minutes, 700 parts by weight of methanol was added to prepare a back coat coating solution. Subsequently, the following photosensitive solution was applied to the surface of the above substrate, and a photosensitive layer was provided so that the coating weight after drying was 2.5 g / m ² . Photosensitive solution Esterified product of 1,2-diazonaphthoquinone-5-sulfonyl chloride and pyrogallol-acetone resin (described in Example 1 of US Pat. No. 3,635,709) 45 parts by weight Cresol formaldehyde novolak resin 110 parts by weight 2 parts by weight 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine 2 parts by weight Oil Blue # 603 (manufactured by Orient Chemical Industry Co., Ltd.) 1 part by weight Megafac F-177 (Dai Nippon) Fluorochemical surfactant manufactured by Ink Chemical Co., Ltd.) 0.4 parts by weight Methyl ethyl ketone 1000 parts by weight Propylene glycol monomethyl ether 1000 parts by weight

A matte layer-provided PS plate was obtained by spraying the matte layer-forming resin liquid on the surface of the photosensitive layer thus prepared in the following manner. A 12% aqueous solution of methyl methacrylate / ethyl acrylate / acrylic acid (weight ratio of 65:20:15) copolymer with a part of sodium salt was prepared as a mat layer forming resin liquid, and a rotary atomizing electrostatic coating machine was prepared. The atomizing head rotation speed is 25,000 rpm, the resin liquid feed rate is 40 ml / min, the voltage applied to the atomizing head is -90 kV, the ambient temperature during application is 25 ° C, and the relative humidity is 50%. Spray the coated surface with steam for 2.5 seconds to moisten it, and then 3 seconds after moistening, apply warm air with a temperature of 60 ° C. and a humidity of 10% to 5 seconds.
Sprayed for 2 seconds to dry. The height of the mat is about 6μ on average
m, the average size was 30 μm, and the coating amount was 150 mg / m ² . The PS plate thus obtained is 1,003 mm ×
A large number of pieces cut into a size of 800 mm were prepared, and these were exposed through a document film for 60 seconds using a metal halide lamp of 3 kW from a distance of 1 m. The exposed PS plate was treated with the PS processor at 24 m ² per day for a total of 3 days, and the finally treated plate was used as a sample for printing.

Example 2 In Example 1, instead of 7 g of compound [I] -4, 7 g of 1- (3-chloroallyl) -3,5,7-triaza-1-azoniaadamantan chloride was added to the water-washed portion. The same process as in Example 1 was carried out except that the final plate was used as a printing sample. Example 3 In Example 1, 1- (3-chloroallyl) -3,5,
7-triaza-1-azonia adamantan chloride
The same process as in Example 1 was performed except that g was added, and the last plate was used as a printing sample. Example 4 The same procedure as in Example 1 was carried out except that 14 g of compound [II] -4 was added instead of 7 g of compound [I] -4 in Example 1, and the last plate was used as a printing sample. And

Example 5 In Example 3, PS processor PS-900NP
Was changed to PS-900V manufactured by Fuji Photo Film Co., Ltd. (automatic processor of a type in which the washing water was fresh water for each plate), and the same process as in Example 3 was performed to print the last plate. It was used as a sample. Example 6 In Example 2, 1- (3-chloroallyl) -3,
Instead of 7 g of 5,7-triaza-1-azoniaadamantan chloride, 7 g of 1,3,5-trishydroxyethylhexahydro-S-triazine was added to washing water, and PS processor PS-900NP was added to PS- 900
The same process as in Example 2 was performed except that V was changed to V, and the final plate was used as a printing sample. Example 7 Except that the PS processor PS-900NP was changed to PS-900V in Example 2, the same process as in Example 2 was performed, and the final plate was used as a printing sample. Examples 8 and 9 In Example 7, 7 g of compound [I] -2,
A printing sample was prepared in the same manner as in Example 7, except that 7 g of the compound [I] -3 was added. Example 10 In Example 6, 7 g of compound [I] -4 was added,
1,3,5-Trishydroxyethylhexahydro-S
-Instead of 7 g of triazine, 7 g of 3-methyl-4-isopropylphenol and 3 g of diethylene glycol
The same process as in Example 6 was performed except that 5 g was added, and the final plate was used as a printing sample.

Comparative Examples 1 and 2 In Examples 1 and 5, only tap water was used in the washing section, and the same treatments as in Examples 1 and 5 were carried out except that the last plates were used as printing samples.

In order to evaluate the ink receptivity of the printing samples of Examples 1 to 10 and Comparative Examples 1 and 2, the samples were left in advance at 35 ° C. and 85% for 3 days. The samples were mounted on a printing press Harris Aurelia 125 offset printing press and printing was started according to conventional methods. The number of prints until the ink adhered to the image area at that time and a good printed matter was obtained is shown in the column of ink receptivity in Table-1.

[0025]

[Table 1]

According to these results, the compounds of the general formulas [I] and [II] and / or the constitution (5) of the present invention were used as the added compounds.
The systems in which the compound of Example 1 was added to the wash water (Examples 1 to 10) were excellent in ink receptivity, but the systems in which only the wash water was tap water (Comparative Examples 1 and 2) were inferior in ink receptivity. Was there. In addition, these additive compounds also have a bactericidal action,
It was also effective in preventing spoilage in the water-washed part. Further, Example 5
In PS-900V of 6, 7, 8, 9 and 10, due to its mechanism, the washing water to which the additive of the present invention was added was used as a diluting water for the developing solution, the finishing gum and the finishing rinse solution from the supply tank. Were also used, but there was no effect on their performance.

[0027]

INDUSTRIAL APPLICABILITY The additive for washing water of a lithographic printing plate according to the present invention has an effect of preventing a decrease in ink receptivity at the start of printing of the lithographic printing plate.

Claims (4)

[Claims] 1. A rinsing water for a lithographic printing plate comprising at least one compound selected from compounds represented by the following general formulas [I] and [II] as an additive. [Chemical 1] 2. A rinsing water for a lithographic printing plate comprising at least one compound selected from the compound group (a) shown below as an additive. [Compound Group (a)] 1,3,5-Trishydroxyethylhexahydro-S-triazine, 1,3,5-trishydroxymethylhexahydro-S-triazine, 1-
(3-chloroallyl) -3,5,7-triaza-1-azonia adamantan chloride, 2-phenoxyethanol, α-bromocinnamaldehyde, 1,2-benzisothiazoline, methyl 2-benzimidazolylcarbamate, 3-methyl- 4-isopropylphenol, N-
Sodium methyldithiocarbamate, 5-methyl-
1,2,4-triazolo [3.4-b] benzothiazole, N-lauroyl-sarcosine sodium, N-lauroyl-N-methyl-β-aminopropionate sodium, resorcinol, pyrogallol, resorcinol monoacetate, sodium alginate, Disodium ethylenebisdithiocarbamate, 10,10'-oxybisphenoxaarsine, cresol, 2,5-dichloro-
4-bromophenol, 2- (4'-thiazolyl) -benzimidazole, 2,4,4'-trichloro-2'-
Hydroxydiphenyl ether and salts thereof. 3. The additive amount of the wash water is 0.001.
The washing water for lithographic printing plates according to claim 1 or 2, characterized in that 4. A plate-making method in which a photosensitive lithographic printing plate is imagewise exposed, then developed, washed with water, and a hydrophilic plate surface protective layer is further provided on the printing plate. [II], or a compound represented by the compound group (a) as an additive, which is a plate making method.