JPS6260692B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a processing solution for developing or halftone dot reduction of a metal-based image forming material, which is formed by laminating an alkali-soluble metal or metal compound and an alkali-developable photosensitive resin on a support. The image forming material used as a film for plate making, which is made by laminating a thin metal layer and a photosensitive resin layer on a support, has the high resolving power, high gradation, possibility of dot reduction, etc. required for a film for plate making. Many have been announced as satisfying the following. These processing methods can be roughly divided into two types: methods in which the development of the photosensitive resin layer and etching of the thin metal layer are performed using different solutions, and methods in which the same solution is used. The former is, for example, when polyvinyl cinnamate, which is a solvent-developable photosensitive resin, is applied to the photosensitive resin layer. After image exposure, the photosensitive resin layer is developed with a solvent such as xylene, and then acid or alkali is used to develop the photosensitive resin layer. This is a method of etching the thin metal layer exposed on the surface. However, this method has several drawbacks, namely, incomplete removal of residual film in non-image areas during development of the photosensitive resin layer results in uneven etching of the thin metal layer, and difficulty in disposing of waste liquid. There are problems such as long processing time. On the other hand, in the latter case, the development of the photosensitive resin layer and the etching of the thin metal layer are carried out using the same solution, so even if there is a residual film during the development of the photosensitive resin layer, it is removed during etching, so unevenness is less likely to occur. Therefore, it is easy to dispose of the waste liquid, and since etching starts at the same time as the development of the photosensitive resin layer, the total processing time is shortened. On the other hand, thin metal layers can be etched using either alkali or acid. (In reality, most metals have passive states such as oxides on their surfaces. Generally, such oxides dissolve in alkalis, but they are difficult to dissolve in acids, and it is difficult to uniformly etch them with acids. Therefore, it is most desirable to have a system that can process both the photosensitive resin and the thin metal layer with alkali at the same time.)However, alkali-developed type photosensitive resins are generally not immersed in alkali for a long time or exposed to highly concentrated alkali. When immersed, the photosensitive resin in the image area that is not normally dissolved also dissolves or swells. On the other hand, the etching rate of a thin metal layer increases as the alkali concentration increases. Therefore, when the alkali concentration is increased to improve the etching speed and shorten the development processing time, the photosensitive resin in the image area swells and peels off, and when the alkali concentration is lowered to suppress swelling, the development processing time tends to become longer. It was hot. In addition, in the plate-making process, an operation called halftone reduction is performed to reduce the area of the formed halftone dots as a correction of the halftone dot image. The force reduction is performed by etching only the thin metal layer in the lateral direction while leaving the photosensitive resin layer as it is. For this reason, halftone reduction requires a higher etching speed than development and uses an alkaline solution with a higher concentration than the developer, making the problems of swelling of the photosensitive resin and lengthening of processing time even more serious. In order to solve this problem, there is a proposal to increase the etching rate by co-evaporating aluminum and a metal that has a smaller ionization tendency than aluminum to form a thin metal layer (Japanese Patent Application Laid-Open No. 1983-1980-1).
139720). However, this is not a definitive method, and only slightly increases the etching speed, so it cannot be put to practical use. In addition, by forming a layer made of a silane coupling agent between the thin metal layer and the photosensitive resin layer and improving the adhesion between the thin metal layer and the photosensitive resin, it is possible to improve the adhesion between the thin metal layer and the photosensitive resin. There is also a proposal to prevent the plastic resin from swelling or dissolving and peeling off from the thin metal layer (Japanese Patent Application Laid-Open No. 135641/1983). However, this method also has a small effect and has not been put into practical use. Furthermore, the metal-based thin layer has low mechanical strength, and scratches and pinholes are likely to occur when steps such as surface treatment are increased.
Therefore, it is desired to solve the drawbacks without applying any processing to the metal-based image forming material itself, such as on the metal-based thin layer or the photosensitive resin layer.
However, no attempt has been made to increase the resistance of the photosensitive resin layer to alkali and prevent swelling by changing the composition of the processing liquid. It is also known that a surfactant is added to the processing solution to improve the developability and wettability of the photosensitive resin (Japanese Patent Laid-Open No. 52-99811). However, this was intended to improve the dissolution of the non-image areas of the photosensitive resin layer, and did not delay the swelling of the photosensitive resin layer in the image areas. In view of these shortcomings, the present inventors investigated processing liquids for developing metal-based image forming materials or reducing halftone dot power, found a processing liquid that could meet the above objectives, and completed the present invention. did. That is, the present invention provides an alkaline solution for use in the development and/or halftone reduction of a metal-based image forming material, which is formed by laminating an alkali-soluble metal or metal compound layer and an alkali-developable photosensitive resin layer on a support. An image-forming material processing liquid characterized in that the aqueous solution contains at least (a) periodic acid or metaperiodate and (b) an alkali metal hydroxide having an atomic weight of potassium or more. The present invention will be explained in detail below. Metal-based image forming materials to which the present invention can be applied include:
It is formed by sequentially laminating at least three layers: (1) a support layer, (2) an alkali-soluble metal thin layer, and (3) an alkali-developable photosensitive resin layer. The support is preferably a transparent and flexible film, such as polyethylene terephthalate, polypropylene, polyethylene, polyvinyl chloride,
Polyvinylidene chloride, polycarbonate, cellulose acetate, etc. can be used. Alkali-soluble metal thin layers include aluminum, zinc, lead, tin, tellurium, bismuth, iron,
Nickel, titanium, copper, chromium, their alloys, oxides, nitrides, borides, carbides, sulfides, salts, etc. are applicable. Vacuum deposition, sputtering, high frequency ion plating, etc. can be applied to lamination of this metal thin layer on the support. If the layer thickness is too thin, the light-shielding property will be insufficient and the difference in density between the image area and the non-image area will be small; if the layer thickness is too thick, etching will take longer and the processing time will be longer. Further, in order to improve the adhesion to the support, the support may be subjected to plasma treatment or fire treatment, or an undercoat layer may be provided before providing the metal thin layer. On the other hand, any photosensitive resin may be used as long as it can be developed with alkali. Generally known diazo-based, diazide-based, cinnamoyl-based, and acryloyl-based photosensitive resins are used. Diazo systems include systems that combine quinone diazides and novolac resins, while diazide systems include polymers made by esterifying partially saponified polyvinyl acetate with azidophthalic anhydride, and polyvinyl alcohol with P-azidobenzaldehyde and phenolic hydroxyl groups. Examples include those acetalized with aldehydes. Examples of the cinnamoyl type include cinnamic acid dibasic acid mixed ester of polyvinyl alcohol and cinnamic acid ester of styrene-maleic anhydride copolymer. Acryloyl-based compounds include (1) ethylenically unsaturated compounds that chain polymerize with free radicals, such as pentaerythritol triacrylate, and (2) alkali-soluble polymeric binders, such as styrene-maleic acid copolymers. (3) A system in which a free radical generator such as benzophenone-Michael's ketone or dimethylaminoacetophenone is mixed is exemplified. An image forming method using a metal-based image-forming material having the above-described structure includes first (1) bringing the photosensitive surface of the metal-based image-forming material into close contact with a transmission type original, and (2) irradiating light from the original side. and (3) the soluble portion of the resist (photosensitive resin layer) is dissolved with an alkaline aqueous solution, and at the same time or thereafter, the exposed portion of the metal or metal compound is etched to obtain a metal image. And finally (4) wash with water and dry. In addition, if the formed image is a halftone image and requires correction, (5) the metal can be immersed in a reducing liquid, which is an alkaline aqueous solution, or by bringing the reducing liquid into contact with the correction area with a brush or dropper. Alternatively, the metal compound portion is etched to reduce the dot area, and then (6) washed with water and dried. Next, the processing liquids, that is, the developing liquid and the reducing liquid, which are central to the present invention, will be described. Here, the developer is the liquid used in (3) of the image forming method described above, and the reducing liquid is the liquid used in (3) of the image forming method described above.
This is the liquid used in (5). Each will be explained below. The processing liquid according to the present invention can be used to develop and/or reduce halftone dots of a metal-based image forming material formed by laminating an alkali-soluble metal or metal compound layer and an alkali-developable photosensitive resin layer on a support. The alkaline aqueous solution used for hydration is characterized by containing at least an oxidizing agent and an alkaline agent having the following characteristics. When etching a metal-based image forming material having the above-mentioned structure in which a metal or a metal compound is used as a light-shielding layer with an alkaline aqueous solution, air bubbles are generated.
It is necessary to add an oxidizing agent to the alkaline aqueous solution to suppress the generation of bubbles. JP-A-48-65927 uses NaOCl as an oxidizing agent, but this is explosive and dangerous. Also, JP-A-52-
In No. 99101, M(BrO ₃ ) _p , Mm(ION) _p (M is a mono- to trivalent metal, m: 1, 2, 3, 5, n; 3,
4, 6, p: 1, 2, 3) is applied, but
Most have little effect. Suitable oxidizing agents for this system are periodic acid or metaperiodate. This oxidizing agent has the effect of preventing the generation of bubbles and greatly accelerating the etching rate. Furthermore, since the swelling rate of the photosensitive resin is not affected by the addition of an oxidizing agent, the development processing time can be significantly shortened without the photosensitive resin being swollen by the alkaline aqueous solution (see Examples). . In addition, as the alkaline agent, sodium hydroxide is generally used in an image forming method that etches a metal or a metal compound.
However, in the treatment solution of the present invention containing periodic acid or metaperiodate as an oxidizing agent, sodium hydroxide produces water-insoluble orthoperiodate, which reduces the etching rate. Similarly, orthoperiodate is produced in lithium hydroxide. This precipitation occurs more frequently as the concentration of the alkaline agent and oxidizing agent increases, so it is not possible to increase the concentration of the treatment solution in order to shorten the treatment time. In addition, carbonates such as sodium carbonate and potassium carbonate, and phosphates such as sodium phosphate are used as developing solutions for alkaline development type photosensitive resins, but metals or metal compounds of metal-based image forming materials are used. These compounds have weak basicity and cannot be used alone as an alkaline agent for processing (dissolving). Therefore, suitable alkali agents in this treatment solution are alkali metal hydroxides having an atomic weight greater than potassium, ie, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. When this alkaline agent is used in combination with the above-mentioned oxidizing agent and alkylammonium salt, no precipitation occurs even if the concentration is increased, and the etching rate does not decrease (see Examples). Moreover, in addition to these, an alkylammonium salt can also be included in the present treatment liquid. As an alkyl ammonium salt [R ₁ = C ₁₂ to C ₁₈ saturated or unsaturated hydrocarbon, X ^- = Br ^- or Cl ^- or I ^- ] [R ₁ , R ₂ = C ₁₂ to _{C 18} saturated or unsaturated hydrocarbon, X ^- = Br ^- or Cl ^- or I ^- ] [R ₁ =C ₁₂ -C ₁₈ saturated or unsaturated hydrocarbon, X ⁻ Br ⁻ or Cl ⁻ or I ⁻ ] alone or in mixtures are suitable. These alkylammonium salts have the property of forming a film in an aqueous solution. Therefore, if the above-mentioned alkylammonium salt exists in the developer, it forms a film on the surface of the photosensitive resin layer in the image area of the metal image forming material, causing swelling of the photosensitive resin by the alkaline aqueous solution or unnecessary removal of the photosensitive resin. Prevents dissolution. Moreover, etching of the thin metal layer by an alkaline aqueous solution cannot be prevented. However, when it is applied as a processing solution for development, it tends to delay removal of non-image areas, so it is not necessary to add it. The above-mentioned alkylammonium salts belong to cationic surfactants, but with anionic surfactants, nonionic surfactants, and zwitterionic surfactants, etching is significantly inhibited by the coating formed on the thin metal layer. Of the alkylammonium salts mentioned above, it is particularly effective in protecting photosensitive resins and improving the etching rate of thin metal layers. [ _R1 = _C12 - _C18 saturated or unsaturated hydrocarbon, ^X- = ^Cl- ] is most preferred. Furthermore, in this processing liquid, in order to improve the developability of the photosensitive resin layer or the speed of reduction, a solvent that does not dissolve the cured photosensitive resin but swells it can be added. The applicable solvents include normal or iso alcohols having 1 to 5 carbon atoms or ethylene glycol having 1 to 5 carbon atoms.
Cellosolves such as mono- or diesters of No. 4 are preferred. In addition, in order to suppress pH fluctuations that occur with the use of the processing solution, a salt with a buffering effect can be added. This salt includes trisodium phosphate,
Salts of weak acids and strong bases such as sodium polyphosphate, sodium borate, and sodium carbonate are suitable. When using this processing solution as a developer, it is important to have a wide latitude code for development conditions such as development time and temperature, uniformity of development, and stability, so the concentration of the processing solution should be an alkaline agent: 0.01~
Preferably, the amount is 0.90 mole/oxidizing agent: 5 to 100 mole% of the alkaline agent, and the alkyl ammonium salt: 0 to 5 wt%. In addition, when used as a reducing solution, the processing temperature is low, such as room temperature or tap water temperature, and the etching rate needs to be higher than the development.
A concentrated developer is applied. Alkaline agent: 0.05 to 4.0 mol/Oxidizing agent: Alkaline agent 5
~100 mol%, alkylammonium salt: 0.5~
5wt% is preferred. Further, the amount of solvent added is preferably less than 10 wt % because if it becomes excessive, the photosensitive resin layer will peel off during development or reduction. Further, the amount of the salt having a buffering effect to be added is suitably 10 to 300 mol%, preferably 10 to 200 mol% of the alkaline agent. If the processing solution of the present invention having the above composition is applied, the etching rate of the thin metal layer will be greatly increased by the addition of the oxidizing agent, and the addition of the alkyl ammonium salt will increase the etching rate of the photosensitive resin layer against alkali. Since the resistance is increased, the occurrence of pinholes is greatly reduced, and it is also possible to increase the concentration of the processing solution, thereby increasing the etching rate. In addition, unlike lithium hydroxide and sodium hydroxide, by using an alkali metal hydroxide with an atomic weight greater than potassium as an alkali agent, precipitation does not occur even at high concentrations, so the processing time is reduced by increasing the concentration of the processing solution. It becomes possible to shorten the
In addition, since the liquid is highly stable, the life of the liquid is extended, and the effects will not be diminished even if the treatment liquid is left for a long time. Furthermore, if applied to a reducing solution, the thin metal layer is etched while the photosensitive resin in the halftone dot area is protected from the alkaline solution by the alkylammonium salt, improving the halftone shape of the reducing solution and significantly reducing image unevenness. decreases to Therefore, if this processing liquid is applied as a processing liquid for metal-based image forming materials, processing time can be shortened, image quality, and stability of the processing liquid can be significantly improved. This invention will be explained in more detail below using examples. [Example 1] A photosensitive solution having the composition shown in Table (A) was prepared.

[Table] Next, aluminum was vacuum-deposited to a thickness of 1000 Å on a 100 μm polyethylene terephthalate film to obtain a small piece (P). Next, a photosensitive solution having the composition shown in Table (A) was coated on the vapor-deposited aluminum surface of the piece (P) using a spin coater to a dry film thickness of about 1 μm. On the photosensitive resin layer is PVA with a saponification degree of 88% and a polymerization degree of 500.
A 5 wt % aqueous solution of was applied using a spin coater to a dry film thickness of approximately 2 μm. The entire surface of the film thus obtained was exposed to light for 20 seconds using a 3KW jet light printer manufactured by Oak Co., Ltd. to photocure the photosensitive resin layer, and then washed with water to remove the PVA layer (small pieces (Q). This film was immersed for 10 minutes in a 0.02 mol/aqueous solution of the oxidizing agent shown in Table (B) at 30°C, but there was no change in the photosensitive resin layer.
KOH 0.35 mol/and oxidizing agent from table (B) 0.10 mol/
The aluminum was immersed in an aqueous solution at 30°C, and the time until the aluminum completely dissolved was measured.

【table】 Next, the aluminum etching time is shown in Table (C).

【table】

[Example 2]

A treatment solution having the composition shown in Table (D) was prepared, and the small piece (Q) produced in Example 1 and the small piece of aluminum-deposited polyester film (P) were immersed at the same time (30
℃), the time required for the photosensitive resin in the pieces (Q) to swell and the time required for the aluminum in the pieces (P) to come off were measured, and at the same time, the stability of the liquid was checked. The results are shown in (E).

【table】

[Table] [It can be seen from Table (E) that it is stable in alkaline aqueous solutions with a larger atomic weight than potassium, but unstable in lithium and sodium. (Example 3) A treatment liquid having the composition shown in Table (F) was prepared and an experiment similar to that in Example 2 was conducted. The results are shown in Table (G).

【table】

【table】

[Example 4]

A photosensitive solution having the composition shown in Table (H) was prepared.

[Table] An aluminum layer (1000 Å) was provided on a 100 μm polyethylene terephthalate film by vacuum deposition, and a photosensitive solution having the composition shown in Table (H) was applied thereon to a dry film thickness of 1.5 μm using a roll coater. After drying the solvent, a 15 wt % polyvinyl alcohol aqueous solution was further layered using a roll coater and dried to produce a metal image forming material. The 150 line/inch soft dot halftone image outputted from Scanner SG701 (Dainippon Screen) was brought into close contact with the above metal image forming material, and then printed at 5 mJ/cm ² using a 3KW jet light printer (Oak Seisakusho).
Image exposure was performed. Next, the polyvinyl alcohol layer was removed with water, and the sample was immersed in a developer having the composition shown in Table (I) below (temperature controlled at 30°C), and rubbed lightly with a sponge.

[Table] As a result, a metal image that had a negative-positive relationship with the original was formed in about 25 seconds. The film on which the desired metal image was formed was immediately washed with water and fixed. Since the photosensitive resin in the image area was protected from alkali by the addition of an alkyl ammonium salt, the image formed had fewer pinholes, a high gamma value, and was sharp. Moreover, no clouding was observed in the developer even after it was left for two weeks. Next, place the film on which the desired image has been formed (J).
It was immersed in a reducing solution (23℃) for 30 seconds.

[Table] After that, it was washed with tap water. After drying, the halftone dot area was measured using a halftone dot area meter (manufactured by Toyo Ink), and the area was 53.0% before the reduction in force, but was 45.5% after the reduction in force. Further, the halftone dots after power reduction were sharp without fringes, and no decrease in density in the image area was observed. Also, after leaving this force reducing liquid for a day and night, the force was reduced in the same way, and the force was reduced by about 8% in 30 seconds.

Claims (1)

[Claims] 1. Development and/or dot reduction of a metal-based image forming material formed by laminating an alkali-soluble metal or metal compound layer and an alkali-developable photosensitive resin layer on a support. A treatment for an image-forming material, characterized in that the alkaline aqueous solution used for the treatment contains at least (a) periodic acid or metaperiodate and (b) an alkali metal hydroxide having an atomic weight of potassium or more. liquid. 2. The processing liquid for image forming materials according to claim 1, which contains an alkylammonium salt represented by (). (R ₁ is a C ₈ to C ₂₀ alkyl group, R ₂ - _{R 4} are H,
_CH3 , _C2H5 , _{C8 to C20} alkyl group, or
[Formula] X ^- is Cl ^- or Br ^- or I ^- ) 3 The processing liquid for image forming materials according to claim 2, wherein the alkylammonium salt is a compound represented by (). (R ₅ is a C ₁₀ to C ₁₈ alkyl group, X ^- is I ^- or
^Cl- or ^Br- ). 4 Salt of weak acid and strong base to alkaline agent 10~
The processing liquid for metal-based image forming materials according to any one of claims 1 to 3, characterized in that the processing liquid contains 300 mol%. 5. The processing liquid for metal-based image forming materials according to claims 1 to 4, which contains 0 to 10 wt% of a solvent that swells the photocured photosensitive resin without dissolving it.