JPS62204261A - Photomechanical process for positive type photosensitive printing plate - Google Patents

Abstract

PURPOSE:To provide superior examinability to a printing plate by using a free radical producing agent having absorption wavelength different from the absorption wavelength of o-quinone diazide and by irradiating the image part with light by which o-qunone diazide is hardly sensitized. CONSTITUTION:A positive type photosensitive printing plate contg. o-quinone diazide, a free radical producing agent having the main absorption wavelength on the lower wavelength side of the main absorption wavelength of o-quinone diazide, and a dye which discolors by a reaction with a free acid produced by the photolysis of the free radical producing agent is imagewise exposed, developed, and uniformly exposed with light by which the free radical producing agent is principally sensitized and o-quinone diazinde is not practically sensitized. thus, the free radical producing agent is sensitized without practically sensitizing the o-quinone diazide to allow the color development type printing out agent to develop color, so the examinability of the printing plate can be improved.

Description

[Detailed description of the invention] [Field of invention] The present invention relates to a method for making a photosensitive printing plate.

More specifically, the present invention relates to a plate-making method that can provide positive photosensitive printing plates with excellent plate inspection properties.

[Prior art]

Positive-working photosensitive printing plates are produced by taking advantage of the fact that the solubility in a developer increases upon irradiation with light.

It has been conventional practice to impregnate the photosensitive layer of this photosensitive printing plate with a dye to make the image easier to see during plate making or printing. Furthermore, positive-working photosensitive printing plates are also known which are provided with so-called print-out properties, which immediately provide visible contrast corresponding to the image upon exposure. For example, JP-A-50-36209 discloses that free radicals are generated by light irradiation in a positive photosensitive composition consisting of a sulfonic acid ester or sulfonic acid amide of an 0-quinone diphosphate compound and a novolak resin. A positive-working photosensitive composition is described in which print-out properties are imparted by adding 0-naphthoquinofdiazide-4-sulfonic acid halide as a compound and an organic dye having salt-forming ability.

Conventionally, a positive transparent original image is brought into close contact with the surface of a photosensitive layer using a vacuum printing frame, exposed to actinic light (image exposure), developed with a developer, washed with water, and unnecessary image parts (transparent original image and A widely used method is to apply erasing liquid to dirt attached to the glass of the vacuum printing frame, film edges, register marks, etc. with a brush, wash with water to erase, and then apply gum to obtain a printing plate. has been done. In addition, blurring may occur due to embedded tape, dust, or insufficient vacuuming, so this is checked by inspecting the plate before printing. In such erasing and plate inspection work, it is convenient to make the color of the image area as dark as possible to make the fine details easier to see. On the other hand, during exposure work, for positioning purposes, a ten-shaped mark (called a dragonfly) is made with a blue ballpoint pen at a fixed location on the photosensitive printing plate, and this is superimposed on the ten-shaped mark imprinted on the positive transparent original. is widely practiced. At this time, it is desirable that the color of the printing plate be as light as possible in order to make the 10-shaped mark made with a blue ballpoint pen easier to see.

Due to the conflicting demands mentioned above, conventional photosensitive printing plates usually have a density (D = 0.7
~1.0) Nishishi. For this reason, none of the operations were satisfactory, and the efficiency of the plate-making operations was hindered.

In order to solve these problems, the color of the plate should be light before exposure and dark during plate inspection.

Therefore, if a color-forming printing-out agent is added, the color can be made lighter before exposure and darker after exposure. Incidentally, in a positive-working photosensitive printing plate, exposed areas are alkali-solubilized to form non-image areas, and unexposed areas form image areas. Therefore, in order to deepen the color of the image area for plate inspection, it is necessary to expose the image area to light after exposure and development to cause the image area to develop color. However, when the image area is exposed to light, 0-quinonediazide undergoes a photoreaction and becomes a carboxylic acid form, causing a disadvantage that did not exist before dawn. One of them is a reduction in the burning effect. A photosensitive composition composed of 0-quinonediazide and 7-unol resin is generally heated at a temperature of 220°C or higher for 3 minutes or more (hereinafter referred to as "burning treatment") to form an extremely strong film, which can be used without burning treatment. The printing durability is improved by 2.5 to 3 times. However, when 0-quinonediazide photoreacts to form a carboxylic acid, burning treatment has a weak effect;
．． It only increases by about 5 to 2 times.

The second problem is that the image area in which 0-quinonediazide is in the carboxylic acid form has high solubility and is less resistant to various chemicals used on printing presses. For example, if a plate cleaner is used, the exposed image area will be damaged more quickly than the unexposed image area, making it impractical.

As described above, exposing the quinone diazide in the image area to light would cause a big problem, so it was not possible to actually adopt the method of irradiating the image area with light in order to improve plate inspection properties.

[Purpose of the invention]

Therefore, it is an object of the present invention to include a photosensitive layer in the image area after image exposure and development. - To provide a method of developing color with print-out dye and providing excellent plate inspection properties without exposing quinone diazide to light.

[Structure of the invention]

As a result of various studies, the inventors of the present invention found that they used a free radical generating agent that has an absorption wavelength that deviates from the absorption wavelength of 0-quinonediazide, and sensitized this free radical generating agent to light. The inventors have discovered that the above object can be achieved by irradiating the image area with light of a wavelength that does not interfere with the image area, and have completed the present invention.

That is, the present invention provides 0-quinonediazide, a free radical generating agent having a main absorption wavelength on the lower wavelength side than the main absorption wavelength of the 0-quinonediazide, and a free acid generated when the free radical generating agent is photodecomposed. After imagewise exposure and development of a positive-working photosensitive printing plate containing a dye that changes color upon reaction, the printing plate is exposed using light such that mainly the free radical generator is sensitized and the 0-quinonediazide is not substantially sensitized. This is a method for making a positive photosensitive printing plate, which is characterized by exposing the entire surface to light.

O-quinonediazide generally has a main absorption wavelength in the range of 360 to 420 nm. The present invention uses light that has no or almost no spectral energy in this wavelength range to expose the entire surface to light, thereby exposing the free radical generator to light without substantially exposing the 0-quinone diazide, and color-forming printing. It is characterized by coloring the release agent and improving plate inspection properties.

As a free radical generator, outside the range of 360 to 420 nm,
For example, one having a main absorption wavelength of 320 nm is used.

The difference between the main absorption wavelength of 0-quinonediazide and the main absorption wavelength of the free radical generating agent is preferably 20 nm or more, more preferably 30 nm or more, and most preferably 40 nm or more.

The entire surface exposure is preferably performed using light having spectral energy of 70% or more at 370 nm or less. Also, 3
The entire surface may be exposed through a filter that blocks light of 60 to 420 nm and allows light of shorter wavelengths to pass.

The contents of the present invention will be explained in detail below.

The positive-working photosensitive printing plate used in the present invention uses a photosensitive composition containing 0-quinone diazide, a free radical generator, and a color-forming printout dye as described below.

As the 0-quinonediazide, for example, U.S. Patent No. 3.0
No. 46.110, No. 3.046.111, No. 3.
No. 046.112, No. 3.046.115, No. 3
．． No. 046.118, No. 3.046.119, No. 3.046.120, No. 3.046.1.21,
Same No. 3.046.122, Same No. 3.046.123, Same No. 3.061゜430, Same No. 3.102.809
No. 3.106.465, No. 3.635.70
Including the specifications of No. 9 and No. 3.647.443,
Those described in numerous publications can be suitably used. Among these, O-naphthoquinonediazide sulfonic acid ester or 0-naphthoquinonediazidecarboxylic acid ester of an aromatic hydroxy compound, and O-naphthoquinonediazide sulfonic acid amide or O-naphthoquinonediazidecarboxylic acid amide of an aromatic amino compound are particularly preferred. , especially U.S. Patent No. 3.635.7.
A condensate of pyrogallol and acetone described in the specification of No. 09 is subjected to an ester reaction with 0-naphthoquinonediazide sulfonic acid, US Patent No. 4.0'28゜1.1
0-naphthoquinonediazide sulfonic acid to the polyester having a hydroxyl group at the end described in Specification No. 1
or an ester reaction of 0-naphthoquinonediazidecarboxylic acid, a homopolymer of p-hydroxystyrene as described in U.S. Pat. No. 4,139,384, or other copolymerizable monomers therewith. copolymer with O-naphthoquinonediazide sulfonic acid or O
- ester reaction of naphthoquinone diazide carboxylic acid, copolymer of p-aminostyrene and other copolymerizable monomers as described in U.S. Pat. No. 3,759,711, and 0- Those obtained by subjecting naphthoquinonediazide sulfonic acid or 0-naphthoquinonediazidecarboxylic acid to an amide reaction are very good.

Although these 0-quinonediazide compounds can be used alone, it is preferable to mix them with an alkali-soluble resin and provide this mixture as a photosensitive layer. Suitable alkali-soluble resins include novolak-type phenolic resins, specifically phenol formaldehyde resins,
-cresol formaldehyde resin, m-cresol formaldehyde resin, etc. Additionally, U.S. Patent No. 4
As described in No. 123, 279, condensation of phenol or cresol substituted with an alkyl group having 3 to 8 carbon atoms, such as t-butylphenol formaldehyde resin, and formaldehyde together with the above-mentioned phenol resin. It is even more preferable to use it in combination with The alkali-soluble resin is present in the photosensitive layer in an amount of about 50 to about 85% by weight;
More preferably, it is contained in an amount of 60 to 80% by weight.

Examples of free radical generators whose absorption spectra do not substantially overlap with those of the above-mentioned 0-quinonediazide include haloalkyl-s-) +Jryojin compounds represented by the following general formula (I) and the following general formula (1'[) A haloalkyl oxadiolizole compound represented by is suitable.

(X represents a halogen atom. Y is -CX3, NL,
Represents NHR', NR' 2 and OR'.

R' here represents an alkyl group or an aryl group.

Further, R is an alkyl group, a substituted alkyl group, an aryl group,
Represents a substituted aryl group or substituted alkenyl group. ) N □ N R' (where W represents an optionally substituted aryl group or heterocyclic ring, R' is a hydrogen atom, an alkyl group or an aryl group, X is a fluorine atom, a chlorine atom or a bromine atom, n is 1~
It represents an integer of 3, and p represents O or 1. ) W is an aryl group (e.g., phenyl group, naphthyl group) or a heterocyclic ring (e.g., indole ring, etc.) which may have a substituent, and typical examples of the substituent include nitro, cyano, etc. , nor\rogen atom, phenyl, lower alkyl (1 to 6 carbon atoms), lower alkoxy (1 to 6 carbon atoms)
~6), phenoxy, and acetoxy groups.

R' is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group, and representative examples thereof include a methyl group, a propyl group, and a phenyl group.

Specific examples of the free radical generator represented by the above general formula (1) include those described in Bulletin of Chemical Society of Japan, written by Kuhai et al., Chem.

Soc, Japan) Vol. 42, p. 2924 (1969
2-phenyl-4,6-bis(trichloromethyl)-s-)riazine, 2-(p-chlorophenyl)-4,6-bis(trichloromethyl)-s-
) riazine, 2-(p-)lyl)=4,6-bis(trichloromethyl)-s-) riazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-S-
) riazine, 2-(2',4'-dichlorophenyl)-
4,6-bis(trichloromethyl)-S-triazine,
2゜4.6-)lis(trichloromethyl)-s-)riazine, 2-methyl-4,6-bis(trichloromethyl)
-s-) riazine, 2-n-nonyl-4゜6-bis(trichloromethyl)-S-) riazine, 2-(α, α, β
-trichloroethyl)-4,6-bis(trichloromethyl)-S-triazine and the like. Also, compounds described in British Patent No. 1.388.492, such as 2-styryl-4°6-bis(trichloromethyl)-
S-)Ryazine, 2-(p-methylstyryl)-4,6
-bis(trichloromethyl)-s-) riazine, 2-(
p-methoxystyryl 14.6-bis(trichloromethyl)-s-)riryojin, 2-(p-methoxystyryl)
-4-amino-6-trichloromethyl-S-triazine and the like can be mentioned. Additionally, the Journal of Organic Chemistry (J, Org.) by Schaefer et al.

Chem, ); Vol. 29, p. 1527 (1964), such as 2-methyl-4,6-bis(tribromomethyl)-s-)riazine, 2,4,6-tris(tribromomethyl) -S-) riazine, 2.4.6-
) lis(dibromomethyl)-s-) liazine, 2-amino-4-methyl-6-tribromomethyl-S-triazine, 2-methoxy-4-methyl-6-trichloromethyl-S-) riazine, etc. I can do it.

It is particularly preferable to use a compound of general formula (I) in which Y is -Cx3.

On the other hand, specific examples of the free radical generating agent represented by general formula (II) include the following.

CH3 l13 CH3 It is suitable to contain these in the range of 0.1 to 5% by weight of the positive photosensitive composition, more preferably 0.3% by weight.
-3% by weight.

Next, as the color-forming printout dye, for example, the following can be used, but the invention is not limited thereto.

Congo Red, Benzobarbunone 4B, Methyl Yellow, Benzeneazodiphenylamine, Orange ■, Methyl Orange, Methyl Red, Ethyl Red C) 1. Azo dyes such as CH, 0H, p* indicators such as cresol red, bromocresol purple, and pentamethoxy red, phthalide color formers such as crystal violet lactone, malachite green lactone, and spiropyran color formers.

Since these color-forming print-out dyes often change color from yellow to red or from red to blue, a blue dye may be added separately to give the photosensitive layer a bluish tinge to give a subdued color tone to the entire photosensitive layer. For example, the following blue dyes can be used.

Sumiplast Blue
) OR.

Sumiplast Green
en)G.

(Aizen 5piron Blue) GNII
(manufactured by Hodogaya Chemical Industry), Orient Oil Green BG (before Orient Chemical).

These dyes determine the color density of the positive-working photosensitive printing plate, but the important thing is that the photosensitive printing plate before exposure must have a low density (D = 0.85 or less) that makes it easy to see the register marks. Furthermore, the density of the exposed area must be sufficiently high (D=0.95 or higher) to be easily erased and inspected.

As described above, the positive photosensitive composition used in the present invention mainly consists of 0-quinonediazide, an alkali-soluble resin free radical generator, and a color-forming print-out dye (and a blue dye if necessary). Other dyes, pigments, plasticizers, etc. can be contained as necessary.

A positive-working photosensitive lithographic printing plate (hereinafter referred to as a positive-working PS plate) is obtained by coating such a positive-working photosensitive composition on a support having a hydrophilic surface.

The support includes various types conventionally usable as supports for lithographic printing plates, but aluminum plates are particularly preferred. Suitable aluminum plates include pure aluminum plates and aluminum alloy plates, as well as plastic films laminated or vapor-deposited with aluminum. The surface of the aluminum plate is preferably subjected to a surface treatment such as graining treatment, immersion treatment in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate, or the like, or anodization treatment.

Also, after graining, U.S. Patent No. 2.714.0
Aluminum plate immersed in IJum aqueous solution as described in Specification No. 66, Japanese Patent Publication No. 1973-
As described in Japanese Patent Publication No. 5125, an aluminum plate is anodized and then immersed in an aqueous solution of an alkali metal silicate. Those obtained by oxidizing and then immersing in an aqueous solution of polyvinylphosphonic acid are also suitably used. The above anodizing treatment is, for example,
An electric current is applied to the aluminum plate in an electrolytic solution consisting of an aqueous solution or a non-aqueous solution of inorganic acids such as phosphoric acid, chromic acid, sulfuric acid, boric acid, etc., or organic acids such as oxalic acid, sulfamic acid, or their salts, or a combination of two or more of them. It is carried out by flowing.

Also effective is silicate electrodeposition as described in US Pat. No. 3,658,662.

Furthermore, a support coated with electrolytic grains as disclosed in U.S. Pat. Oxidized products are also useful. Further, chemical etching after graining as described in U.S. Pat. No. 3,834,998,
An aluminum plate which is subsequently anodized is also preferred.

This type of positive type 23 plate can be used to print carbon arc lamps, mercury lamps, metal halide lamps,
Exposure is performed using a light source rich in actinic rays such as a xenon lamp, and the positive type 23 plate used in the present invention is characterized by easy visibility of register marks and ease of exposure work. When the exposed positive-working 23 plate is developed with a developer, the exposed areas of the photosensitive layer are removed and the hydrophilic surface of the support underneath is exposed, yielding a lithographic printing plate. Preferred developing solutions include sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, tribasic sodium phosphate, dibasic sodium phosphate, tribasic potassium phosphate, dibasic potassium phosphate, dibasic ammonium phosphate, dibasic An alkaline aqueous solution containing at least one alkali such as an inorganic alkaline agent such as ammonium phosphate, sodium metasilicate, sodium bicarbonate, aqueous ammonia, etc., or an organic alkaline agent such as monoethanolamine, jetanolamine, etc. is used. The composition of a particularly preferred alkaline aqueous solution is described in detail in US Pat. No. 4,259,434.

The developing method can be carried out by various means such as an automatic developing machine having both a developing and gum section, a conventional automatic developing machine having a water washing section, dish development, and manual development.

Next, the developer is illuminated for re-exposure. In the present invention, post-exposure is performed to make the image after development easier to see, and the feature is that a re-exposure device is used that emits light of a wavelength that does not substantially expose the 0-quinonediazide in the photosensitive layer. . There are two methods for preventing the emission of light that sensitizes 0-quinonediazide. One method is to use a light source that emits light having a spectral energy distribution that does not overlap with the absorption wavelength range of 0-quinonediazide. The other is a normal lamp (
Metal halide, etc.) is used, but the light is exposed through a filter that cuts light in the absorption wavelength range of 0-quinonediazide and passes light in the wavelength range to which the free radical generating agent is sensitive.

For the former purpose, fluorescent chemical lamps FL40BL, FL
Fluorescent lamps that emit little visible light and are rich in ultraviolet rays, such as 40SBLB and health line lamp PL203E (manufactured by Toshiba), and high-pressure mercury lamps, such as H400 (manufactured by Iwasaki Electric), are suitable.

For the latter purpose, an exposure device equipped with a yellow filter as described below may be used.

Diaresin Yellow
ow) HG (manufactured by Mitsubishi Kasei), Solvent Yellow (
Solvent Yellow 56) (C0
1,11021), Spilo
n Yellow) GR (manufactured by Hodogaya Chemical Co., Ltd.) coated with a yellow dye on a transparent base, colored glass filters and interference filters that cut light at the absorption wavelength of 0-quinonediazide.

By using such a re-dawning device, 0-quinonediazide is not exposed to light and the image area develops color, resulting in D=0.95.
As described above, erasing and plate inspection work can be easily performed.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 The surface of an aluminum plate having a thickness of 0.24 mm was grained using a nylon brush and a 400 mesh pumice water suspension, and then thoroughly washed with water.

After etching was performed by immersing it in an IJium aqueous solution (10% hydroxide) at 50°C for 20 seconds, it was washed with running water (20°C) for 1 minute.

Next, using a 1.5% nitric acid aqueous solution, the voltage was 1 at 20°C.
Using 0V sine wave alternating current, the amount of electricity is 900 coulombs/d.
After electrochemical graining for 20 seconds at 70°C, the desmut treatment was performed by immersion in 20% phosphoric acid at 70°C for 30 seconds. After thorough washing with water, 15% sulfuric acid aqueous solution (2
An anodic oxide film of 3.09/m' was formed by direct current at a voltage of 22 V at a temperature of 3.09/m'.

On this support, the following photosensitive liquid was applied and dried to form a photosensitive layer having a weight of 2.59/m' after drying, and a positive type 23
Got the edition.

Photosensitive liquid: Cresol novolak resin 1.98 gp-
t-Butylphenol resin 0.05 g Benzeneathoanhenylamine 0.10 g'Spirone Blue GN8 0.05 g Ethylene dichloride 18 g 2-methoxyethyl acetate 12 g The positive type 23 plate obtained in the above manner has a reflection density of 0. 70, and the dragonfly written on it was easy to see.

Production of yellow filter: Yellow dye Solvent Yellow (SolventYel)
low) 56 (1g) to methylene chloride 1
00g and coated with whiter on a transparent base and dried. The yellow density of the obtained filter was 1.2.

After irradiating the above positive type 23 plate with light for 1 minute using a metal halide lamp 2KW (manufactured by Eye Graphics) through the transparent original, the molar ratio of S+Os/NaJ was 1.2 and it was 5I20.
It was developed with an aqueous sodium silicate solution having a content of 1.5%.

The printing plate thus obtained was irradiated with light in the following manner.

(c) Metal halide lamp (through a yellow filter)
Irradiation (2KW) with a metal halide lamp (2KW) without passing through a yellow filter.
Both of (2) and (2) were irradiated at 2 KW) and had a density of 1.05 in the image area due to color development, and both had satisfactory plate inspection properties.

Comparing both 0) @, the one exposed through the filter in (a) showed the same strength against Plate Cleaner: Ultra (^1 mouth, manufactured by C, Chemical Co.) as the unexposed one, whereas the one exposed to light through the filter in (a) showed the same strength as the unexposed one. When exposed without a filter, the image area was immediately attacked by the plate cleaner (Ultra). The printing durability of this printing plate was 100,000 sheets without burning, but it was 260 sheets.
The thorns (burned for 7 minutes at ℃) grew to 300,000 sheets, while the sides only grew to 150,000 sheets.

Example 2 A positive type 98 plate using the developing method was prepared in the same manner as in Example 1. This plate was exposed to 3C using a fluorescent chemical lamp FL40SBLB.
It was exposed to light for 2 minutes from a distance of n+. Example 1 as a comparative example
I made one by exposing it to the same metal halide lamp (2KW) for 1 minute. In both cases, the image density rises to 1.05, but the former is not affected by plate cleaner (Ultra), whereas in the comparative example, when plate cleaner (Ultra) is applied to the image area and left for 10 minutes, the image area melts. .

Example 3 The following photosensitive solution was coated on a support prepared in the same manner as in Example 1 and dried to form a photosensitive layer having a dry weight of 2.59/m'' to obtain a positive PS plate. Ta.

Photosensitive liquid: Cresol novolak resin 1.988p-
The positive PS plate obtained using t-butylphenol resin 0.058 methyl ethyl ketone 5 g or more had a reflection density of 0.50, and the register marks written on it were very easy to see. Further, exposure and development were carried out in the same manner as in Example 1, and exposure was carried out using the method (a) of Example 1. The image density was 1.0, making it easier to inspect the plate. Add plate cleaner (Ultra) to this item for 10 minutes.
Although it was left for a minute, the image area was not affected at all.

〔Effect of the invention〕

According to the present invention, alignment is easy and exposure work is easy, and the image area becomes dark in color by the light exposure process after development, so plate inspection work is easy. Moreover, by further performing a burning treatment, a printing plate with sufficiently improved printing durability can be obtained.

Claims (3)

[Claims] (1) O-quinonediazide reacts with a free radical generating agent having a main absorption wavelength on the lower wavelength side than the main absorption wavelength of the o-quinonediazide, and a free acid generated when the free radical generating agent is photodecomposed. After imagewise exposure and development of a positive-working photosensitive printing plate containing a dye that changes color when the plate is exposed, the entire surface is exposed using light that primarily sensitizes the free radical generator and substantially does not sensitize the o-quinonediazide. A method for making a positive photosensitive printing plate, characterized by: (2) The method according to claim (1), characterized in that the entire surface is exposed to light having a spectral energy of 70% or more at 370 nm or less. (3) The method according to claim (1), wherein the entire surface is exposed through a filter that blocks light of 360 to 420 nm and passes light of shorter wavelength.