JPH0358100B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lithographic printing original plate which is made by light or heat. Representative examples of master plates for lithographic printing include PS plates and electrophotographic plates. PS version (presensitized plate)
is a polyvinyl cinnamic acid ester, methyl methacrylate, acrylated glycidyl acrylate, acrylonitrile copolymer, triethylene glycol diacrylate, and alcohol-soluble copolyamide on a hydrophilic support such as aluminum or zinc that has been made hydrophilic. N,N'-methylenebisacrylamide mixed system, cyclized polyisoprene ~2,6
- Images containing negative photosensitive resins (or photosensitive compounds) such as di(4'-azidobenzal)cyclohexanone mixed systems, paradiazophenylamine/paraformaldehyde condensation products, or positive photosensitive resins such as quinonediazide resins When a negative photosensitive resin is used for plate making, the exposed area undergoes a cross-linking reaction or a decomposition reaction and becomes insolubilized, or its solubility changes to a completely different level than before exposure. After this, the image is generally processed (developed) with an organic solvent to elute the exposed areas, thereby leaving the unexposed areas as a negative image. Plate making is performed in a similar manner when using a positive photosensitive resin, but in this case, contrary to the negative type, the exposed areas decompose and are eluted during development, while at the same time the unexposed areas undergo chemical changes. It becomes insolubilized and forms a positive image. On the other hand, electrophotographic plates are made by providing a photoconductive layer containing photoconductive zinc oxide and a resin binder on a hydrophilic conductive support such as a hydrophilic aluminum vapor-deposited film, and the plate making process is carried out using ordinary electronic methods. After being charged and imagewise exposed according to the photographic method, it is developed with a lipophilic toner. PS plates are widely used in everything from industrial printing to light printing, but because the sensitive wavelength is only in the near-ultraviolet range, the exposure process requires preparing a lithium film using silver halide film and then contact-transmission printing this film. This results in a complicated and expensive printing plate. In addition, since an organic solvent is used during development (although there are some that can be developed with alkaline or water), this generally poses a problem in terms of pollution. On the other hand, electrophotographic plates can be made without using lithographic film like PS plates, but the plate making process is complicated and there are problems such as the need to replace consumables. Furthermore, since the image formed is a toner particle image, the image quality is inferior to that of the PS plate. In addition, with the recent use of computers, facsimile machines, etc., there is a demand for original plates or materials that can be used to make plates using the output signals of these devices, i.e., thermal or optical modes, but conventional original plates or materials cannot meet this demand. I stopped talking. The first object of the present invention is to provide a lithographic printing original plate that can solve various problems in conventional PS plates and electrophotographic plates. A second object of the present invention is to provide a lithographic printing original plate that can be made by a simple method of imagewise exposure or heat application. A third object of the present invention is to provide a lithographic printing original plate which can be made by output signals from a computer, facsimile, etc. That is, the original plate of the present invention is characterized in that an image forming layer containing a tetrazolium salt and a photoreducing agent or a thermal reducing agent as main components is provided on a hydrophilic support. The general formula of the tetrazolium salt used in the present invention is as follows. (However, R ₁ and R ₂ each represent an aryl group or a heterocyclic group, and R ₃ is an alkyl group, an aryl group, a heterocyclic group, a carboxyl group, a carboxy ester group, a mercapto group, a hydroxy group, an amino group, a carbamyl group, represents a sulfone group or a sulfonamide group, and X represents Br, Cl or _BF4 ), or [However, R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₄ and R ₁₅ each represent an aryl group or a heterocyclic group, and R ₁₀ ,
R ₁₁ , R ₁₂ and R ₁₃ represent an alkyl group, an aryl group, a heterocyclic group, a carboxyl group, a carboxy ester group, a mercapto group, a hydroxy group, an amino group, a carbamyl group, a sulfone group, a sulfonamide group, and X is Br , Cl or BF ₄ , and A is

【formula】

【formula】

[Formula] or −(CH ₂ −) represents _o , and B is

【formula】

[Formula] or

[Formula] and C is

【formula】

【formula】

【formula】

【formula】

[Formula] or

Represents [formula]. (However, R ₁₆ represents hydrogen, CH ₃ , OCH ₃ or Cl, and n represents an integer of 1 to 5.) All of the tetrazolium salts represented by the above general formulas () to () are water-soluble and It is insoluble in organic solvents and exhibits a colorless to pale yellow color, but in an excited state it is reduced by a proton abstraction reaction from a proton donor and forms a formazan structure.
It develops a red color and becomes insoluble in water and soluble in organic solvents. The reason why the tetrazolium salt is water-soluble and insoluble in organic solvents is because the tertiary nitrogen is ionized by quaternization.On the other hand, the reason why its reduction product, formazan, is water-insoluble and organic solvent-soluble is due to its azo dye structure. This is thought to be because it takes. In any case, the reduction reaction is thought to proceed as follows in the case of the tetrazolium salt of general formula (). Tetrazolium salt is widely used as an indicator in biochemistry to identify reducing enzymes and reducing sugars, but its colorless to pale yellow color is highly sensitive in the presence of protons (for example, SH enzymes). This is because formazan has two advantages: it exhibits a red color at a low redox potential, and once reduced, formazan is less susceptible to air oxidation. The present inventor focused on the above-mentioned properties and advantages of tetrazolium salts, and as a result of intensive research,
We have arrived at the present invention. Specific examples of tetrazolium salts useful in the present invention are as follows. First, examples of tetrazolium salts of general formula () are shown in Table 1.

【table】

[Table] These tetrazolium salts can be easily synthesized by the known synthesis method shown in the following reaction formula. Incidentally, synthetic examples of these tetrazolium salts are described in detail in the following literature. SSKarmarker,AGEPearse,AM
Seligman: J.Org.Chem., 25 , 575 (1960) P.Frise: Ber., 24 , 4178 (1875) Eiichi Suenaga: Pharmaceutical Journal, 79 , 803, 850 (1959) SALomonosov, IN (Tetsova, Yu. A.
Rybakova: J.Anal.Chem.USSR, 21 , 206
(1966) Akira Kawase: Japan Anal, 16 , 1364 (1967) E.Fischer: Ann., 190 , 188 (1878) Kuhn.R, Murzing.H: Chem.Ber., 86 , 858
(1953) Chemical Reviews, 55 , 335-483 Some of these are also Eastmann Organic
Chemicals, Aldrich Chemical, and Tokyo Kasei. Further, specific examples of the tetrazolium salts of general formulas () to () are shown in Tables 2 to 4.

[Table] The tetrazolium salt of general formula () is synthesized by the synthesis method shown in the reaction formula below.

【table】

[Table] The tetrazolium salt of general formula () is synthesized by the synthesis method shown in the reaction formula below.

【table】

【table】

[Table] The tetrazolium salts in Table 4 are from Aldrich.
Commercially available from Chemical. In any case, the tetrazolium salts of general formulas () to () can be used, for example, SSKarmarker, AGE
Pearse, AUSeligman: J.Org.Chem., 25 , 575
(1980) or Chemical Reviews, 55 , 335
It can be synthesized by the method described in -483. The tetrazolium salt of general formula () is synthesized by the synthesis method shown in the reaction formula below. or, Next, a photoreducing agent and a thermal reducing agent will be explained. A photoreducing agent or a thermal reducing agent refers to a substance that generates protons upon imagewise exposure or heat application. First, as the photoreducing agent, any known photoreducing agent that generates a reducing agent through photolysis or photoinduced rearrangement can be used. for example (disulfide), (Diazoanthrone), (aromatic ketone), (diazophenanthrone), (aromatic azide), (Diazonium salt), (G) Acilloin (H) Aromatic carbazide (I) Aromatic diazosulfonate (2H-benzimidazole) (1H-benzimidazole) (1,3-diazabicyclo[3,1,0]hex-3-enes) (L) External hydrogen source quinones (quinones in combination with an active hydrogen atom source such as polyethylene glycol) e.g.

【formula】

【formula】

【formula】

(M) Internal hydrogen source quinone (quinones containing an active hydrogen atom inside) e.g.

【formula】

【formula】

[Formula] As a thermal reducing agent, OH group or
Those having two or more NH ₂ groups in the o- or p-position relative to each other are effective. That is, those that satisfy the conditions for ordinary silver salt photographic development are also effective in the present invention. For example, polyphenols having two or more phenol groups, mononaphthols, bisnaphthols, polyhydroxybenzenes having two or more hydroxyl groups, polyhydroxynaphthalenes having two or more hydroxyl groups, ascorbic acids, 3- Pyrozolidones, pyrazoline-5
-ones, pyrazolones, phenylenediamines, hydroxylamines, hydroquinone monoethers, hydrooxamic acids, hydrazides, amidoximes, N-hydroxyureas, and the like. These photoreducing agents or thermal reducing agents are dissolved or dispersed in a suitable solvent that is compatible with water, and are applied to a hydrophilic support together with the tetrazolium salts of the general formula () or the tetrazolium salts of the general formulas () to (). The lithographic printing original plate of the present invention can be obtained by coating and drying to provide an image forming layer thereon. The appropriate amount of the photoreducing agent or thermal reducing agent to be used is about 0.20 to 5.00 mol per mol of the tetrazolium salt. As the hydrophilic support, known ones can be used, such as aluminum or zinc plates subjected to hydrophilic treatment, or paper or film coated with a hydrophilic substance. To make the printing original plate of the present invention, the image forming layer of the original plate is exposed to visible light in an imagewise manner, heat is applied in an imagewise manner by a thermal printing means such as a thermal head, or a computer or the like is used. After applying a facsimile output signal, for example, a signal carried by a laser beam, to make the exposed part or the heat applied part insoluble in water, the unexposed part or the heat applied part can be dissolved and washed by immersing it in water. . Examples will be shown to explain the present invention in more detail. Example 1 9,10-phenanthrenequinone (external hydrogen source quinone) 2 x 10 ^-2 mol polyethylene glycol (molecular weight 600) (active hydrogen atom source) 1.0 mol ethyl alcohol/acetone (1/1 volume ratio)
25ml After uniformly dissolving a mixed solution of 2 x 10 ^-2 moles, this solution was applied to a 100 μm thick aluminum plate that had been made hydrophilic by anodizing using a glass doctor so that the dry film thickness was 20 μm, and was dried to form an image. By providing layers, a lithographic printing original plate was obtained. The original plate obtained in this way was passed through a glass filter (<410 nm) at a distance of 30 cm.
When a 500W tungsten lamp was used to expose the negative original for 20 seconds, the exposed areas turned red and a clear positive image was formed. Next, when this was immersed in water, the non-exposed areas were washed away and the hydrophilic surface of the aluminum was exposed, yielding a printing plate. Example 2 The following tetrazolium salt was used as the tetrazolium salt used in the image forming layer solution: A lithographic printing original plate was obtained in the same manner as in Example 1 except that . Thereafter, exposure and water washing were performed in the same manner as in Example 1 to obtain a printing plate having a red positive image. Example 3 1,4-dinaphthol 2×10 ^-2 mol A lithographic printing original plate was prepared in the same manner as in Example 1 using a mixed solution consisting of 10 ml of 1×10 ^-2 molar water. When the original plate thus obtained was printed with a thermal head (temperature: 250°C) attached to a commercially available facsimile machine, the areas to which heat was applied developed a black-purple color, forming a sharp image. Next, by immersing this in water and washing the non-image area with water, the hydrophilic surface of the aluminum was exposed to light, and a printing plate was obtained. Example 4 A mixture consisting of 2.5 g of a 10% aqueous solution of 2×10 ^-2 mol PVA (molecular weight 500) (active hydrogen atom source), riboflavin (vitamin B ₂ ) (external hydrogen source quinone), and 10 ml of a 2×10 ^-2 mol 5% aqueous NaOH solution. A lithographic printing original plate was prepared in the same manner as in Example 1 using the solution. A red colored image was formed by irradiating the original plate thus obtained with an argon ion laser having a wavelength of 488 nm at a recording energy density of 5 mJ/cm ² . Thereafter, water washing was performed in the same manner as in Example 1 to obtain a printing plate.

Claims (1)

[Claims] 1. A lithographic printing original plate comprising an image forming layer containing a tetrazolium salt and a photoreducing agent or a thermal reducing agent as main components on a hydrophilic support.