JPS582854A - Method for making printing plate - Google Patents

Abstract

PURPOSE:To form a printing plate good in reproductivity of thin lines and high in printing resistance, by processing a toner image formed on a raw printing plate by the electrophotographic method, with a specified aqueous etching solution. CONSTITUTION:An aqueous etching solution to be used consists of 0.05-10wt% alkaline agent, such as a hydroxide of an alkali metal or aminophenols, and 1- 6wt% benzyl alcohol and/or phenethyl alcohol dissolved in water. An electrophotographic toner image is formed on a photosensitive layer, provided on a raw printing plate, containing an organic photoconductor using a styrene-maleic anhydride copolymer or the like having 30,000-300,000mol.wt. and 80-300 acid value as a binder. The toner image is processed with said etching solution to etch off only the part of the photosensitive layer except the toner image, thus permitting a desired printing plate to be obtained.

Description

Detailed Description of the Invention The present invention is a printing method in which a toner image is formed by electrophotography using an organic photoconductive compound, and a non-image area other than the toner image forming area is etched with an alkaline solution. Concerning the plate making method.

Many electrophotographic printing plates using organic photoconductive compounds are already known, for example, Japanese Patent Publication Nos. 37-17162 and 3
No. 8-6961, No. 41-2426, No. 46-394
No. 05, JP-A-50-19509, JP-A No. 50-1951
No. 0, No. 54-19803, No. 54-89801,
Examples include No. 54-134632, No. 54-145538, and No. 55-105254.

According to a general plate-making method, a toner image is formed on an electrophotographic original plate using an organic photoconductive compound by a normal electrophotographic method, and then non-image areas other than the toner image are etched using an alkaline agent. It is made into a plate by processing with a solution.

As the toner used for image formation, both so-called dry toner and wet toner can be used, but in order to obtain printed matter with excellent resolution, wet toner using a liquid development method is far more preferable. However, while wet toner has excellent resolution, it has poor adhesion and adhesion to the photosensitive layer, and during the etching process, the photosensitive layer beneath the toner is etched, making it difficult to obtain fine line reproducibility. It has not been put into practical use due to its shortcomings. The above-mentioned drawbacks of liquid toners become more serious because liquid toners form images with good resolution.

In the electrophotographic printing plates mentioned above, which are made using the difference between the etching properties of the toner and the etching properties of the photosensitive layer, the toner is not etched at all and the toner does not adhere, regardless of whether it is a dry toner or a wet toner. By quickly etching only the photosensitive layer other than the photosensitive layer, printed matter with better fine line reproducibility can be obtained.

The toner must not only be non-etchable and therefore resistive when etched, but also be hydrophobic, ink-receptive, and have sufficient adhesion to withstand multiple printings. .

On the other hand, the photosensitive layer is much more easily etched than the toner, and on the other hand, it is required to not be excessively etched, but on the other hand, it must form a strong film that can retain the toner to the extent that it can withstand printing on a large number of sheets after etching. must have a sexual nature. Examples of the binder for the photosensitive layer having such characteristics include styrene maleic anhydride copolymer, maleic ester resin, vinyl acetate-crotonic acid copolymer, vinyl acetate-maleic anhydride copolymer, acrylic ester, and methacrylate. These binders have a large molecular weight, preferably about 30,000 to about 300,000, and have a large acid value, preferably about 80,000 to prevent etching with an alkaline solution. ~300 is suitable.

In order to obtain good fine line reproducibility, it is important to select the toner and the binder for the photosensitive layer, but it is also important to select a suitable etching solution.

The alkaline etching solution used in such elutriation methods does not fully meet the above-mentioned requirements.

The purpose of the present invention is to improve the drawbacks in the plate-making method of printing plates using organic photoconductive compounds, and to achieve printing with high printing durability and good fine line reproducibility without impairing the resistivity of toner. An object of the present invention is to provide a plate-making method suitable for printing plates, especially printing plates using a liquid development method.

JP-A-5L-77401 discloses a method for removing unexposed areas of a lithographic printing plate (known as a PS plate) made of an organic polymer having an acid value of 10 to 100 and a photosensitive diazo compound. , a developer composition comprising an anionic surfactant, benzyl alcohol, an alkaline agent, and water has been proposed.

Since the PS plate is cured (photocured) in the exposed areas, there is a large difference in etchability from the unexposed areas, and therefore a developer with relatively high etching development power can be used. However, in the electrophotographic printing plate making method of the present invention, there is no difference in the etching properties of the photosensitive layer, so in order to obtain good fine line reproducibility, the resistivity of the toner and the etching properties of the photosensitive layer must be extremely adjusted. A suitable etching solution is required. If the etching speed is slow, only unsatisfactory fine line reproducibility will be obtained, and if the etching speed is too fast, even the toner image will be etched, making it no longer usable.

Each component of the etching developer described in the above patent plays an important role, and if even one component is missing, etching development of PS plates becomes virtually impossible. Also, the etching development rate increases as the amounts of anionic surfactant and benzyl alcohol are increased, and such an etching developer appears to be preferred for the method of the present invention. However, contrary to expectations, it has been found that the application of such an etching developer is not compatible with the method of the present invention.

The above prediction was further brought to the present invention by the discovery of the fact that the anionic surfactant either does not play any role in the etching properties or worsens the etching properties as the amount increases.

The composition essentially consisting of water, an alkaline agent, and benzyl alcohol used as the etching solution used in plate making by the electrophotographic method described above does not impair the resistivity of the toner image, and only etches the photosensitive layer other than the toner image area. It has been found that printing plates can be etched quickly and have good fine line reproducibility. It has also been found that when phenethyl alcohol is used in place of or in addition to benzyl alcohol, it can be used as an etching solution in the same manner, and the etching rate is faster than that of benzyl alcohol. Benzyl alcohol and phenethyl alcohol are
Substituted derivatives such as those described in 29461 may also be used.

As mentioned above, the etching treatment solution used in the present invention does not require an anionic surfactant, and as the amount is increased, etching becomes worse. If this is included, the etching process will obviously pose a practical problem.

Therefore, the etching solution used in the present invention may be used for other purposes, such as improving the solubility of benzyl alcohol or phenethyl alcohol, within a range that does not significantly inhibit etching properties, for example, up to about 5% by weight depending on the conditions. Although it may be used, it is preferable not to include it from the viewpoint of etching properties. The amount of phenethyl alcohol or benzyl alcohol or their combination is
The amount is in the range of 1 to 6% by weight, preferably 2 to 5% by weight of the etching solution, but a certain range of amount may be allowed as necessary. Excessive amounts can speed up the etching speed, but may also etch the toner image, the photosensitive layer under the toner image, or even the binder, affecting printing durability even when no visible etching occurs. .

The etching solution used in the present invention includes sodium hydroxide, potassium hydroxide, sodium silicate, potassium silicate, tribasic sodium phosphate, dibasic sodium phosphate, tribasic ammonium phosphate, sodium metasilicate, and alkaline agents. Inorganic alkaline agents such as sodium carbonate and ammonia, nalkylamines such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, n-butylamine, mono-, di- or triethanolamine, monoisopropylamine Knolamine, diisopropanolamine, triisopropanolamine, diethylaminoethanol, 2-
Examples include amino alcohols such as 7 minnow 2-methyl-propanol, and organic amine compounds such as ethyleneimine, ethylenediamine, and pyridine. Preferred are alkali metal hydroxides and amino alcohols. The amount of alkaline agent ranges from about 0.05 to 10% by weight.

In the etching solution used in the present invention, alcohols and cellosolves such as methanol, ethanol, isopropanol, butanol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, methyl cellosolve, and ethyl cellosolve may also be used as necessary. be able to.

In the electrophotographic printing plate used in the present invention, it is preferable to use a photosensitive layer binder containing an organic photoconductive compound that has a large molecular weight and a large acid value. Molecular weight is about 30,000 or more, preferably about 50,000 to about 300,000, and acid value is about 80.
Above, preferably about 100 to about 300.

Examples of the organic photoconductive compound used in the printing plate used in the present invention include the following compounds.

(a) Aromatic tertiary amine compounds nitriphenylamine, diphenylbenzylamine, di(β-naphthyl)benzylamine, diphenylcyclohexylamine, etc.

(b) Aromatic tertiary diamino compound: N, N, N
',N'-tetrahensyl-1p-phinylenediamine, N,N,N',N'-tetrabenzylbenzicine, 1
, 11-bis-(4-N,N-dibenzylaminophenyl)-ethane, 2.2-bis-(4-N,N.

-dibenzylaminophenyl)-butane, bis-(4-
N,N-di(P-chlorobenzylaminophenyl))
-methane, 3,3-diphenylallyridine-4,4'-
Bis(N,N-diethyl-luidi/), 4.4'-
bis(di-p-tolylamino)1,1.1-)liphenylethane, and the like.

(C), aromatic tertiary triamino compound 24,4',4
″=-tris(diethylaminophenyl)methane, 4-
Dimethylamino, 4.4n-bis(diethylamino)-
2,2″-dimethyl-triphenylmethane, etc.

(d) Main condensation product: condensation product of aldehyde and aromatic amine, reaction product of tertiary aromatic amine and aromatic halide, poly-roofunisine-1,3,4-oxadiazole, formaldehyde and reactants of fused polycyclic compounds, etc.

(e) Metal-containing compounds = 2-mercaptobenzothiazole zinc salt, 2-mercapto-benzoxazole lead salt, 2-mercapto-6-medoxypenzimidazole-lead salt, S-hydroxy-quinoline-aluminum salt, 2 -hydroxy-4-methyl-azobenzene-copper salt,
(f) Polyvinylcarbazole compound: polyvinylcarbazole, halogen-substituted polyvinylcarbazole,
Vinylcarbazole and styrene copolymers, vinylanthracene-vinylcarbazole copolymers, etc.

Q) Heterocyclic compound: 1,3.5-) Riphenylvirazoline, 1-phenyl-3-(p-dimethylaminostyryl)-5-(p-dimethylaminophenyl)-pyrazoline, 1,5-diphenyl -3-styryl-pyrazoline,
1.3-diphenyl-5-styryl-hylasoline, 1,
3-diphenyl-5-((p-dimethylaminophenyl)-pyrazoline, 3-(4'-dimethylaminophenyl)-5,6-di(4''-methoxyphenyl)-1,2
,4-1 riazine, 3-(4'-dimethylaminophenyl)-5,6-dipyridyl-1.2.4-1 riazine,
2-phenyl-4-(4-dimethylaminophenyl)-
Quinazoline, 6-hydroxy-2,3-di(P-methoxyphenyl)-benzofuran, 2,5-bis-[4'-
ethylamino-phenyl-(1')-1,3,4-oxadiazole and the like.

Further, the organic photoconductive compounds used in the present invention include phthalocyanine pigments, quinacridone pigments, indigo pigments, cyanine pigments, perylene pigments, bisbenzimidazole pigments,
Good printing plates can also be obtained using pigments such as quinone pigments, azo pigments, and indigo pigments.

As the printing plate pace in the present invention, all conventional printing plate pastes can be used. for example,
Metal plates such as aluminum plates, zinc plates, magnesium plates, copper plates, etc.

Examples include films made of polyester, cellulose acetate, polystyrene, polycarbonate, polyamide, polypropylene, etc., synthetic paper, processed paper such as resin-coated paper, etc., but photoconductive compounds and binders are removed by etching treatment after image formation. Since the non-image area must have hydrophilic properties, the paste having a hydrophobic surface must be subjected to a hydrophilic treatment in advance.

A metal plate, particularly an aluminum plate, is most suitable, but surface treatments such as grain treatment, alkali treatment, acid treatment, and anodization are preferred. In the case of films, it is preferable to coat them with a relatively highly hydrophilic polymer compound and perform crosslinking treatment, or to vapor-deposit or bond them with some kind of metal. When using an insulating paste, it is desirable to conductive treatment on the surface of the paste.

To produce a printing original plate, the photoconductive compound and binder are dissolved in a solvent; if the photoconductive compound is not dissolved, a dispersion is prepared using a colloid mill, homogenizer, ultrasonic disperser, etc.); A sensitizing dye and the like are added and coated onto the support to a thickness of 1 to 30 μm and dried. The ratio of the photoconductive compound to the binder is 0.01 to 50 parts by weight of the binder to 1 part by weight of the photoconductive compound, preferably 0.2 to 10 parts by weight, although it varies depending on the binder and photoconductive compound used. is appropriate.

Those that can be used as solvents include all organic solvents that are capable of dissolving the binder and dissolving or dispersing the photoconductive compound.

For example, alcohols such as methanol, ethanol, gropanol, phthanol, and hexyl alcohol, cellosolves such as butyl cellosolve, ethyl cellosolve, butyl cellosolve, aromatics such as benzene, toluene, and xylene, cyclic ethers such as dioxane and tetrahydrofuran, and ethyl acetate. , esters such as butyl acetate and amyl acetate, ketones such as acetone, methyl isobutyl ketone, and methyl ethyl ketone, dimethyl formamide, dimethyl sulfoxide, and halogenated hydrocarbons, but from the viewpoint of solubility, cost, safety, etc. A mixture of two or more solvents is often used.

The toner used for image formation may be either a so-called dry toner or a wet toner.

The features of the present invention are fully exhibited, particularly when a liquid development method is used. Examples of toners that can be used include styrene resins, acrylic resins, polyester resins, and epoxy resins. In addition, it is practically preferable to contain pigments and dyes for coloring, and a charge control agent within a range that does not adversely affect the safety and fixing properties of the donor.

Example 1 A binder solution was prepared by dissolving 100 tons of butyl methacrylate-methacrylic acid having a molecular weight of 120,000 and an acid value of 150 in a mixed solvent of 500 tons of xylene and 200 tons of butanol. In this solution, 1,
3.5-) 70 l of Riphenylpyrazoline was dissolved, 50 t of a 1% DMF bath solution of Rhodamine B as a sensitizing dye was added, and the total amount was adjusted to 1000 t with xylene. Coat it on a grained and anodized aluminum plate of 100μ so that the solid content is 5φ″ and dry to obtain a thick layer for printing.

In a dark place, expose the halftone image with white light to the phoenix for printing in a dark place. We held a meeting and thermoelectrodeposited f's...r''C manufactured by -.

Next, immerse it in the following etching J6111E and toner ■
Other than the spear, Onon II - Iku O Al Zemaro is exposed to etching and measures 0 hours.

, Kuko νchi)//J&IIm! > JP 51-774 with any of the above etching solutions
Even when the PS plate described in No. 01 was processed for more than 1 minute, almost no etching development occurred. On the other hand, when the printing plate was treated by adding 70 tons of sodium isopropylnaphthalate to the etching solution, the time required for etching was several times longer.

Provided is a method for making an electrophotographic printing plate in which the edges of minute halftone dots are firm and fine line reproducibility is good.

Furthermore, after washing the printing plate obtained in this way with water, using the ink of compound Jinshitatsuku 15, Ryobi K.
A printing durability test was conducted using an R2700 printing machine.

In each case, more than 20,000 clear prints were obtained.

Example 2 Example 1 was carried out using a printing original plate prepared in the same manner except that a vinyl acetate-crotonic acid copolymer having a molecular weight of 150,000 and an acid value of 180 was used as a binder for the organic photoconductive compound.
repeated. Similar results were obtained.

Example 3 100 tons of methyl methacrylate-butyl acrylate-crotonic acid copolymer having a molecular weight of 100,000 and an acid value of 130 was dissolved in a mixed solvent of 500 tons of toluene and 200 tons of butanol to prepare a binder solution.

In this solution, 70% of 4.4"-bis(diethylamino)-2,2"-dimethyl-triphenylmethane was dissolved as an organic photoconductive compound, and 80f of a 1% DMF' solution of ethyl violet was dissolved as a sensitizing dye. In addition, the total amount was adjusted to 1000 tons with xylene. It was coated on the aluminum plate used in Example 1 so that the solid content was 5 It/rn' and dried to obtain a printing original plate.

Thereafter, a toner image was formed in the same manner as in Example 1, and the sample was immersed in the following etching/etching solution. Only the non-image area was etched in about 7 seconds, and it was confirmed that the printing plate had good halftone dot reproducibility and high printing durability.

(Work ν Chinda mm *> Next 01St work as actual bar 114~6??!//JllI
llIK was rounded and printed with a side layer of Isai Confucian 1's printing original phoenix. I/% deviation was also carried out and 0 results were obtained for the same machine as 1110J611Kan C.

Actual stick 84 Actual stick Confucian violence Actual stick Confucian - ``Dieterua 1 no ethanol 80 Procedural amendment February 2, 1980 Director General of the Patent Office Shima 1) Haruki Tono1, Indication of the case 1988 Patent application No. 100971 No. 2
, name of the invention, method for manufacturing printing plates 3, relationship with the case of the person making the amendment Patent applicant 4, agent residence Mitsubishi Paper Mills Co., Ltd., 3-4-2 Marunouchi, Chiyoda-ku, Tokyo 100 5, amendment Date of order: Showa, Month, Day 6, Number of inventions increased by amendment: None +11 “Toner safety” on page 16, line 7 of the specification is corrected to “toner stability” (2) Same page 16, line 12 Corrected line ``methacrylic acid'' to ``methacrylic acid copolymer'' (3) Corrected page 17, line 3, ``positive charge'' to ``negative charge''

Claims (1)

[Claims] (1) After forming a toner image on a printing original plate having a layer containing an organic photoconductive compound by electrophotography, the non-image area other than the toner image forming area is essentially treated with an alkali agent and benzyl alcohol or/and phenethyl alcohol. Printing characterized in that it is treated with an aqueous etching treatment solution containing (the treatment solution does not contain an anionic surfactant or may contain an anionic surfactant in an amount that does not substantially inhibit etching). How to make a plate.