JPS6216834B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a plate surface protective agent for lithographic printing plates, and in particular to an emulsion type plate surface protective agent. When making a lithographic printing plate, the non-image area (area that retains water and repels printing ink) is removed in the final process.
plate surface protectant (so-called gum liquid) to protect
A process called gumming is performed. Gas pulling is used not only to increase the hydrophilicity of the non-image areas of the lithographic printing plate (also called under-sensitization), but also to
When handling a lithographic printing plate, such as when installing it on a printing press, to prevent the lithographic printing plate from deteriorating during the period after plate making and before printing, or during the period from interrupting printing to restarting it. In order to prevent non-image areas from becoming ink-receptive and dirty due to finger oil, rubber, etc. adhering to them, when handling the lithographic printing plate, be sure to wash the non-image areas and image areas with water. This is done for the purpose of preventing scratches from occurring on the areas (areas that repel and receive printing ink). Among the gum liquids used for such gumming, the one with the best performance is an oil phase containing an organic solvent-soluble lipophilic substance and an emulsifying surfactant dissolved in an organic solvent, and a water-soluble dextrin dissolved therein. An emulsified gum solution consisting of an aqueous phase and an aqueous phase is known.
When a lithographic printing plate is gummed with this gum solution, the image area is protected by the lipophilic substance in the oil phase, while the non-image area is protected by adhesion of water-soluble dextrin in the aqueous phase. Therefore, there is little reduction in the oil sensitivity of the image area caused by the adhesion of water-soluble dextrin to the image area. However, even if this emulsified gum liquid is used, it is not possible to sufficiently prevent a decrease in the oil sensitivity of the image area. Therefore, an object of the present invention is to provide a plate surface protective agent for lithographic printing plates that does not reduce the oil sensitivity of the image area. As a result of various studies to achieve the above object, the present inventor discovered that HLB (Hydrophile-Lipophile-
The inventors discovered the surprising fact that the oil sensitivity of the image area does not decrease by containing an alkyl phenyl type nonionic surfactant with a Balance) of 14 or less and an anionic surfactant, leading to the present invention. It is. That is, the present invention provides an aqueous phase containing a hydrophilic polymer compound dissolved therein, an organic solvent,
The present invention is an emulsion-type lithographic printing plate surface protective agent characterized by comprising an oil phase containing an alkyl phenyl type nonionic surfactant having an HLB of 14 or less and an anionic surfactant. The most characteristic ingredient used in the present invention
An alkyl phenyl type nonionic surfactant with an HLB of 14 or less and an anionic surfactant will be explained. The alkyl phenyl type nonionic surfactant having an HLB of 14 or less is preferably a compound represented by the following general formula () and having an HLB of 14 or less. (In the formula, R represents an alkyl group, p is 1 or 2
, m represents an integer of 1 to 4, and n represents an integer of 2 or more. ) The alkyl group of R is preferably selected from alkyl groups having 8 to 18 carbon atoms, and specifically, octyl group, nonyl group, decyl group, undecyl group, dodecyl group (lauryl group), tetradecyl group, hexadecyl group. Examples include a group (cetyl group), and the most preferred are an octyl group and a nonyl group. Further, the substitution position of R is mainly used at the para position with respect to the -O(-C _n H _2n O)- _o H group, but it may also be at the meta or ortho position. Moreover, p is preferably 1, and m is preferably 2. Furthermore, n varies depending on the type of alkyl group of R, but
Any range is sufficient as long as the HLB value is 14 or less, and more preferably a range of 4 to 12. H.L.B.
A desensitizing agent using a desensitizing agent with a value greater than 14 has the disadvantage of reducing the oil sensitivity of the image area of the lithographic printing plate. Specific examples of such alkyl phenyl type nonionic surfactants having an HLB of 14 or less include polyoxymethylene octyl phenyl ether, polyoxymethylene nonylphenyl ether, polyoxymethylene cetyl phenyl ether, and polyoxymethylene nonylphenyl ether having an HLB of 14 or less. Polyoxymethylene lauryl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene decyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxypropylene octyl phenyl ether, polyoxy Propylene nonyl phenyl ether, polyoxypropylene decyl phenyl ether, polyoxypropylene lauryl phenyl ether, polyoxypropylene cetyl phenyl ether, polyoxybutylene octyl phenyl ether, polyoxybutylene nonyl phenyl ether, polyoxybutylene de Examples include sylphenyl ether, polyoxybutylene lauryl phenyl ether, polyoxybutylene cetyl phenyl ether, and polyoxyethylene dinonyl phenyl ether. Particularly suitable for the present invention are those based on polyoxyethylene, and polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, and the like are particularly preferably used. On the other hand, examples of anionic surfactants which are another characteristic component used in the present invention include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, and dialkyl sulfosuccinate esters. These include anionic surfactants such as salts, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, and polyoxyethylene alkyl sulfate ester salts, but dialkyl sulfosuccinates give particularly favorable results. The alkyl group of the dialkyl sulfosuccinate preferably has 2 to 18 carbon atoms,
For example, sec-butyl group, t-butyl group, hexyl group, 2-ethylhexyl group, nonyl group, decyl group, dodecyl group, etc. are preferable. Specific dialkyl sulfosuccinates include sodium dihexyl sulfosuccinate, di(2-ethylhexyl)
These include sodium sulfosuccinate, sodium dinonylsulfosuccinate, sodium dilaurylsulfosuccinate, etc. A plate protective agent containing a combination of an alkylphenyl type nonionic surfactant and an anionic surfactant does not reduce the oil sensitivity of the image area more than a plate protective agent containing each surfactant alone. The amount of each of these activators used is in the range of about 0.5 to about 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the plate surface protective agent. The ratio of the alkylphenyl type nonionic surfactant to the anionic surfactant is in the range of 10:1 to 1:10, more preferably 5:1 to 1:5, by weight. The above two types of surfactants are dissolved in an organic solvent to constitute the oil phase of the plate surface protection agent of the present invention. Preferred organic solvents are water-insoluble, such as turpentine, xylene, toluene, n-heptane,
Hydrocarbons such as solvent naphtha, kerosene, mineral spirits, petroleum fractions with a boiling point of about 120° to about 250°C, such as dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate, di(2-ethylhexyl) phthalate , phthalic acid diesters such as dinonyl phthalate, didecyl phthalate, dilauryl phthalate, butylbenzyl phthalate, such as dioctyl adipate,
Aliphatic dibasic acid esters such as butyl glycol adipate, dioctyl azelate, dibutyl sebacate, di(2-ethylhexyl) sebacate, dioctyl sebacate; epoxidized triglycerides such as epoxidized soybean oil, such as tricresyl phosate; Phosphate, trioctyl phosphate, trischlorethyl phosphate, and other phosphoric acid esters, for example, benzoic acid esters such as benzyl benzoate, have a freezing point of 15°C or lower and a boiling point of 300°C or higher at 1 atmosphere. Contains plasticizers. In addition, together with these solvents, for example, ketones such as cyclohexanone, halogenated hydrocarbons such as ethylene dichloride, ethylene glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monophenyl ether, ethylene glycol monobutyl ether, etc. may be used in combination. can do. These solvents should be added in an amount of about 0.1 to
It is used in an amount of about 10% by weight, more preferably in the range of 0.5-5% by weight. It is preferable that the oil phase further contains a lipophilic substance dissolved therein. As a result, the stability of the plate surface protecting agent of the present invention as an emulsion is further improved, and the decrease in oil sensitivity of the image area can be further reduced. Preferred lipophilic materials include lipophilic resins used as vehicles for lithographic printing inks. Specifically, novolak-type phenol resins such as phenol formaldehyde resin, cresol formaldehyde resin, and t-butylphenol formaldehyde resin, xylene resins in which phenol and xylene are condensed with formaldehyde,
Resin made by condensing phenol and mesitylene with formaldehyde, polyhydroxystyrene, brominated polyhydroxystyrene, cashew resin, partial esterified product of copolymer of styrene and maleic anhydride, melamine resin, alkyd resin, polyester resin, epoxy resin , rosin, for example hydrogenated rosin, modified rosin such as rosin ester, petroleum resin such as gilsonite, etc. Among these, novolak type phenolic resin, rosin and modified rosin are preferred. Other preferred lipophilic substances include 5 to 25 carbon atoms, such as oleic acid, lauric acid, valeric acid, nonylic acid, capric acid, mystylic acid, palmitic acid, etc.
Contains organic carboxylic acids, castor oil, etc. These lipophilic substances can be used alone or in combination of two or more, and range from about 0.05 to about 5% by weight, more preferably from 0.1 to 1% by weight, based on the total weight of the plate surface protectant of the present invention. It can be used in On the other hand, the water-soluble polymer compound contained in the aqueous phase of the plate surface protecting agent of the present invention is a component that protects the non-image areas of the lithographic printing plate, and is preferably a water-soluble resin capable of forming a film. For example, dextrin, gum arabic, alginates such as sodium alginate, water-soluble celluloses such as carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, water-soluble copolymers containing acrylamide units, vinyl methyl Examples include a copolymer of ether and maleic anhydride, and a copolymer of vinyl acetate and maleic anhydride. Among these, particularly preferred are gum arabic, dextrin, polyvinylpyrrolidone,
Carboxymethyl cellulose, polyvinyl alcohol, and gum arabic is most preferred. These water-soluble polymer compounds can be used alone or in combination of two or more. In particular, it is preferable to use dextrin together with gum arabic because the hydrophilicity of the non-image area can be increased without reducing the oil sensitivity of the image area. The water-soluble polymer compound is contained in the aqueous phase in a wide range of concentrations, but is generally about 5 to about 40% by weight, more preferably 10 to 30% by weight based on the total weight of the printing plate protectant of the present invention. %, and the concentration in the aqueous phase is from about 6 to about 60% by weight, preferably from 15 to 50% by weight. Preferably, the aqueous phase further contains a wetting agent. Thereby, the property can be imparted that the aqueous phase of the plate surface protective agent of the present invention spreads appropriately to the non-image areas of the lithographic printing plate. Preferred such wetting agents are polyhydric alcohols, and preferred specific examples include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, tetramethylene glycol, polyethylene glycol, Propylene glycol,
Examples include tripropylene glycol, glycerin, sorbitol, pentaerythritol, etc.
Particularly preferred is glycerin. The wetting agent is used in an amount of about 0.5 to about
It can be used in an amount of 10% by weight, more preferably 1 to 5% by weight. Preferably, the aqueous phase further contains a water-soluble salt. As a result, when the plate surface protectant of the present invention is applied to a lithographic printing plate, the non-image area becomes more hydrophilic. Suitable water-soluble salts include alkali metal salts and ammonium salts, and those that give particularly good results include acetic acid, molybdic acid, boric acid, nitric acid,
Included are water-soluble alkali metal and ammonium salts of acids such as sulfuric acid, phosphoric acid and polyphosphoric acid.
Specifically, ammonium acetate, sodium acetate,
Potassium acetate, sodium molybdate, potassium molybdate, sodium borate, ammonium borate, lithium nitrate, sodium nitrate, potassium nitrate, monobasic sodium phosphate, dibasic sodium phosphate, tribasic sodium phosphate, monobasic potassium phosphate, dibasic potassium phosphate, Examples include tribasic potassium phosphate, tribasic ammonium phosphate, and sodium polyphosphate. Among the above, particularly preferred are potassium acetate, sodium borate, ammonium borate, potassium nitrate, sodium molybdate, potassium molybdate, and potassium sulfate. Such water-soluble salts may be used alone or in combination of two or more, and may be used in amounts of approximately
It is used in a range of 0.05 to about 2% by weight, more preferably 0.1 to 1% by weight. When the water-soluble polymer compound dissolved and contained in the aqueous phase is gum arabic, the aqueous phase
The pH is adjusted to be in the acidic range, more preferably 1-5, most preferably 1-3. Therefore, if the PH of the aqueous phase is not acidic, more acid is added to the aqueous phase.
Examples of acids that can be added as pH adjusters include mineral acids such as phosphoric acid, sulfuric acid, and nitric acid, and organic acids such as citric acid, phosphoric acid, malic acid, glacial acetic acid, emulsifying acid, oxalic acid, and p-toluenesulfonic acid. can be exemplified. Among these, phosphoric acid is particularly excellent because it not only functions as a pH adjuster but also prevents stains in non-image areas, and is effective against the total weight of the water phase.
The content is preferably 0.1 to 8% by weight, most preferably 0.5 to 5% by weight. Next, a typical manufacturing method of the plate surface protective agent of the present invention will be explained. First, a water-soluble polymer compound is dissolved in water to prepare an aqueous phase. If the aqueous phase further contains a wetting agent, water-soluble salt and/or acid, these are also added and dissolved. Meanwhile, an oil phase is prepared by dissolving a surfactant in an organic solvent. If the oil phase further contains a lipophilic substance, this is also added. The oil phase thus obtained is dropped into the aqueous phase while stirring, and the resulting mixture is further emulsified using a homogenizer to obtain the plate protection agent of the present invention. The plate surface protective agent of the present invention can be used for various lithographic printing plates, but in particular, a photosensitive lithographic printing plate (preliminarily imparted with photosensitivity) having an aluminum plate as a support plate and a photosensitive layer thereon. In the print version
It's called the PS version. ) can be suitably used for lithographic printing plates obtained by imagewise exposure and development. Preferred such PS plates are, for example, those made of a mixture of diazo resin (salt of a condensate of p-diazodiphenylamine and paraformaldehyde) and silica as described in British Patent No. 1,350,521. The photosensitive layer is provided on an aluminum plate, and the main repeating units are diazo resin and hydroxyethyl methacrylate units or hydroxyethyl acrylate units as described in the specifications of British Patent No. 1460978 and British Patent No. 1505739. Negative types such as those on an aluminum plate with a photosensitive layer consisting of a mixture of polymers with
Includes PS plates and positive PS plates in which a photosensitive layer made of a mixture of an o-quinonediazide photosensitive material and a novolac type phenolic resin is provided on an aluminum plate as described in JP-A-50-125806. . Furthermore, a PS plate in which a photosensitive layer of a photocrosslinkable photopolymer is provided on an aluminum plate as specifically shown in U.S. Pat. No. 3,860,426;
A photosensitive layer of a photopolymerizable photopolymer composition as described in U.S. Pat. No. 4,072,528 and U.S. Pat. No. 4,072,527 was provided on an aluminum plate.
PS version, UK Patent Nos. 1235281 and 1495861
Also preferred is a PS plate in which a photosensitive layer made of a mixture of azide and a water-soluble polymer is provided on an aluminum plate as described in the specifications of the above-mentioned publications. Next, an example of the use of the plate surface protective agent of the present invention when a PS plate is used will be described. First, the PS plate is imaged exposed and then developed to create a lithographic printing plate. After washing the lithographic printing plate with water and squeezing out the water on the plate surface, an appropriate amount of the plate surface protectant of the present invention is poured onto the plate surface and rubbed with a sponge so as to coat the entire surface of the plate. This protects the non-image areas on the plate surface and allows the lithographic printing plate to be stored. To start printing, the gum on the plate is washed off with water, and then printing is carried out according to the normal procedure. The plate surface protective agent of the present invention does not reduce the oil sensitivity of the image area of a lithographic printing plate, while increasing the hydrophilicity of the non-image area. Furthermore, the plate surface protective agent of the present invention has a British patent No.
Particularly remarkable effects are exhibited when used for lithographic printing plates manufactured from the PS plates described in the specifications of No. 1460978 and No. 1505739. Hereinafter, the present invention will be explained in more detail based on examples. Note that % in the examples indicates weight %. Examples 1 to 7 and Comparative Examples 1 to 2 An aluminum plate with a thickness of 0.24 mm was immersed in a 7% aqueous solution of tertiary sodium phosphate at 60°C to degrease it, and after washing with water, a solution in which pumice was suspended in water was poured. While doing so, I scrubbed it with a nylon brush to make it grainy. After washing with water, it was kept at 70°C and immersed in a 5% aqueous solution of JIS No. 3 sodium silicate (SiO ₂ /Na ₂ O (molar ratio) = 3.1 to 3.3) for 30 to 60 seconds. After thoroughly washing with water and drying, the next photosensitive solution A or B was applied. Drying was carried out at 100°C for 2 minutes. Photosensitive liquid (A) 2-hydroxyethyl methacrylate copolymer (synthesized by the method described in Example 1 of British Patent No. 1505739) 0.7 g 2-methoxy-, a condensate of p-diazophenylamine and paraformaldehyde 4-hydroxy-
5-benzoylbenzenesulfonate 0.1g Oil Blue #603 (manufactured by Orient Chemical Industry Co., Ltd.)
0.03g 2-methoxyethanol 6g Methanol 6g Ethylene dichloride 6g Photosensitive solution (B) Photosensitive solution (A) 18.83g Styrene and maleic anhydride copolymer (ratio = styrene:maleic anhydride = 1.5-2:1 molar ratio) 2
- Half ester of methyl-pentanol-4 (Mw≒1500) (trade name Styrite HS-2: manufactured by Daido Kogyo Co., Ltd.) 0.014 g The dry coating weight was 2.0 g/m ² . The photosensitive lithographic printing plates thus obtained were (A) and (B), respectively.
shall be. For each of this photosensitive lithographic printing plates (A) and (B), a 70 cm
Images were exposed for 45 seconds from a distance of Ta. Sodium sulfite 3g Benzyl alcohol 30g Triethanolamine 20g Monoethanolamine 5g Perex NBL (sodium t-butylnaphthalene sulfonate, manufactured by Kao Atlas Co., Ltd.) 30g Water 1000ml Meanwhile, prepare aqueous solution C with the following composition and stir vigorously into it. Meanwhile, Solution D having the following composition was gradually added to form an emulsion, which was further emulsified using a homogenizer to obtain a plate surface protectant. Aqueous solution C Gum arabic 4g Dextrin 16g Phosphoric acid (85%) 0.2g Water 75g Solution D Sodium dilauryl sulfosuccinate 1.0g Dibutyl phthalate 2.0g Alkylphenyl type nonionic activator (Table 1)
1.0g Rosin ester (manufactured by Arakawa Chemical Co., Ltd.) 0.5g After washing the previously obtained lithographic printing plate with water and squeezing out the excess water, apply a small amount of the above plate surface protectant and spread it over the entire surface of the plate with a sponge. It was applied by spreading it evenly. Next, the surface protective agent on the lithographic printing plate was removed by washing with water, and then the plate was set in a printing machine and printing was performed. The oil sensitivity of the printing plate was investigated by measuring the number of plates (hereinafter referred to as the number of coated plates) from the start of printing until an applied product with a sufficient ink concentration was obtained. The results are shown in Table 1.

[Table] From the results in Table 1, it can be seen that the plate surface protective agent according to the present invention has excellent oil sensitivity. Incidentally, the lithographic printing plates made using the plate surface protectants of Examples 1 to 7 and Comparative Examples 1 and 2 gave printed matter without stains. Example 8 A mechanically grained 2S aluminum plate was immersed in a 2% sodium hydroxide aqueous solution kept at 40°C for 1 minute to corrode a portion of the surface. After washing with water,
The surface of pure aluminum was exposed by immersing it in a sulfuric acid-chromic acid mixture for about 1 minute. Immersed in 20% sulfuric acid kept at 30℃, DC voltage 1.5V, current density 3A/dm ²
After performing anodic oxidation treatment for 2 minutes under the following conditions, it was washed with water and dried. Next, a photosensitive solution having the following composition was continuously coated using a roll coater so that the dry weight was 2 g/m ² . Acetone - naphthoquinone of pyrogallol resin -
1,2-diazide(2)-5-sulfonic acid ester (synthesized according to the method described in Example 1 of US Pat. No. 3,635,709) 5 g PR-50530 (tertiary manufactured by Sumitomo Julias Co., Ltd.) Butylphenol-formaldehyde resin) 0.5g Hytanol #3110 (Hitachi Chemical Co., Ltd. cresol-formaldehyde resin) 5g Methyl ethyl ketone 50g Cyclohexanone 40g The plate dried at 100℃ for 2 minutes is
It has the performance of a PS version, and its performance was satisfactory even after one year of use when stored in a cool and dark place. The photosensitive lithographic printing plate made in this way was placed in a vacuum printing frame and exposed to Fuji Film from a distance of 1 m through a transparent positive film.
PS light (Toshiba metal halide lamp MU2000−
2-OL type 3KW light source, Fuji Photo Film
Exposure was carried out for 30 seconds using a camera (sold by Co., Ltd.). Subsequently, the plate was immersed in a developer having the following composition for development. JIS _{No. 3} Sodium Silicate 10g Aerosol OS (Sodium Isopropyl Naphthalene Sulfonate manufactured by American Cyanamid) 20g Benzyl Alcohol 30g Add water to make 1000ml. The resulting lithographic printing plates were washed with water and squeezed, then gummed with each plate surface protective agent shown in Table 2 below, and dried at 80°C for 5 minutes. After leaving each of these plates at 20℃ for 7 days, wash them with water to remove the plate surface protectant, and print according to the normal procedure. (hereinafter referred to as the number of printed sheets) and stains in the non-image area of the printed matter (hereinafter simply referred to as stains) were investigated. The results are shown in Table 2.

[Table] From the above results, it can be seen that the plate surface protective agent of the present invention has an excellent effect of not reducing the oil sensitivity of the image area of the printing plate and causing no staining. Example 9 The same procedure as in Example 3 was carried out, except that K-solvent was used instead of dibutyl phthalate as the organic solvent of the plate surface protectant. The print result is A
Both the plate 1 and the plate B were equivalent to the results obtained in Example 3. Examples 10 to 16 and Comparative Examples 3 and 4 Printing plates were made in the same manner as in Example 1, but using the following as a plate surface protectant, and their oil sensitivity was examined. The results are shown in Table 3. The plate surface protectant was obtained by preparing the following aqueous solution E and solution F and emulsifying them in the same manner as in Example 1. Aqueous solution E Gum arabic 4g Dextrin 16g Phosphoric acid (85%) 0.2g Water 75g Solution F Sodium di(2-ethylhexyl)sulfosuccinate 1.0g Dioctyl phthalate 2.0g Alkylphenyl type nonionic surfactant (tertiary
Table) 1.0g Rosin ester (manufactured by Arakawa Chemical Co., Ltd.) 0.5g

[Table] From the results in Table 3, it can be seen that the plate surface protective agent according to the present invention has excellent performance without reducing the oil sensitivity of the lithographic printing plate.

Claims (1)

[Claims] 1 Consists of an aqueous phase containing a dissolved hydrophilic polymer compound, an organic solvent, an alkyl phenyl type nonionic surfactant with an HLB of 14 or less, and an anionic surfactant. A plate surface protective agent for emulsion type lithographic printing plates characterized by: