JPH0545888A - Exposure method for photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To prevent out-of-focus by printing and a spoilage ratio by disposing a plastic film which allows the transmission of active rays between a pressure contact glass plate and an original picture film and subjecting the film to contact exposing. CONSTITUTION:The plastic film which allows the transmission of the active rays is disposed between the pressure contact glass plate and the original picture film and is subjected to contact exposing in the exposing method for superposing a photosensitive planographic printing plate (PS) plate, the original picture film and the pressure contact glass plate in this order and subjecting these plate and the film to the contact exposing. Any plastic films which substantially allow the transmission of the active rays are satisfactory as the above-mentioned plastic film. The translucent plastic films subjected to matting are included as well. The material quality of the plastic films is simply required to substantially allow the transmission of the active rays and such materials include, for example, polyester, polyvinyl chloride, polyvinylidene chloride, polyvinyl formal, polyvinyl butyral, polyvivnyl thioether, polyvinyl carbazole, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method for a photosensitive lithographic printing plate, and more particularly to an exposure method for a photosensitive lithographic printing plate with less blurring.

[0002]

2. Description of the Related Art Conventionally, a photosensitive lithographic printing plate (hereinafter referred to as "PS
In the plate-making process), the PS plate and the original image film to be overlaid on the PS plate must be in complete contact with each other in order to form a clear exposure image on the PS plate. A so-called vacuum contact exposure method is employed in which a PS plate and an original film are placed between the two and air is discharged between them (in a vacuum state) to bring them into close contact.

However, if a foreign material such as paper dust, cellophane tape, or fiber waste enters between the original film and the PS plate, there is a problem that the image around the foreign material is blurred, that is, so-called blurring occurs. When exposing the original film divided into several sheets on the same PS plate, a transparent base film is pasted with a transparent one-sided adhesive tape (hereinafter referred to as a one-sided adhesive tape) such as so-called tape. I often use inclusive film. Since this sticking film is a sticking tape, poor adhesion occurs around its periphery, causing blurring of the fire, and transparent double-sided adhesive tape, a so-called double-sided adhesive tape, which is used to separate the original film and the transparent base film. Even when used by pasting together, there is a problem in that a burning blur occurs in the peripheral portion of the tape. In fact, the defectiveness of the PS plate at the printing site, that is, the so-called scrap rate is caused by the burning blur.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an exposure method for a PS plate which is less likely to cause burning blurring and has a low scrap rate.

[0005]

The present inventors have completed the present invention as a result of various studies to achieve the above object. The present invention is a photosensitive lithographic printing plate, an original film,
In an exposure method in which pressure-bonded glass plates are superposed in this order and contact-exposed, a photosensitive lithographic printing plate characterized by comprising contact-exposure by disposing a plastic film that transmits actinic rays between the pressure-bonded glass plate and the original film. It is an exposure method.

The present invention will be described in detail below step by step.

[0007]

[PS plate] The PS plate used in the present invention comprises a support having a hydrophilic surface and a photosensitive layer provided on the support. Preferably, the aluminum plate is anodized and then hydrophilized if necessary. A photosensitive layer is provided on the treated support, more preferably a matte layer is provided on the surface of the photosensitive layer.

Aluminum plates used for PS plates include pure aluminum and aluminum alloy plates. Various aluminum alloys can be used, such as silicon, copper, manganese, magnesium, chromium, zinc,
An alloy of aluminum with a metal such as lead, bismuth, or nickel is used. These compositions will contain some iron and titanium, as well as other negligible amounts of impurities.

The aluminum plate is preferably grained, but prior to that, the surface of the aluminum plate is pretreated in order to remove rolling oil from the surface and expose a clean aluminum surface, if necessary. To be done. For the former, solvents such as trichlene and surfactants are used. For the latter, a method using an alkali etching agent such as sodium hydroxide or potassium hydroxide is widely used. As the graining method, a mechanical graining method, a chemical graining method, an electrochemical graining method (so-called electrolytic etching method) and the like are used, and these may be used in combination of several kinds.

The grained aluminum plate is washed with water as needed, and then chemically etched if necessary. The etching treatment liquid used is usually selected from an aqueous solution of a base or acid that dissolves aluminum.
In this case, the etched surface must not form a coating different from aluminum or aluminum derived from the components of the etching solution. Examples of preferable etching agents include sodium hydroxide, potassium hydroxide, trisodium phosphate as basic substances,
Disodium phosphate, potassium phosphate triphosphate, dipotassium phosphate and the like; acidic substances include sulfuric acid, persulfuric acid, phosphoric acid, hydrochloric acid and salts thereof.

The etching is carried out by immersing an aluminum plate in the above-mentioned etching solution or by coating the aluminum plate with the etching solution.
It is preferably treated so as to have a range of 10 g / m ² . It is desirable to use an aqueous solution of a base for the above etching because of its high etching rate. In this case, smut is generated, and thus desmutting is usually performed. As the acid used in the desmutting treatment, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, hydrofluoric acid, etc. are used.

The etched aluminum plate is
If necessary, it is washed with water and then anodized. Anodization can be performed by a method conventionally used in this field. Specifically, when a direct current or an alternating current is applied to aluminum in sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc., or an aqueous solution or a non-aqueous solution in which two or more of these are combined, aluminum is supported. An anodized film can be formed on the body surface.

The treatment conditions for the anodic oxidation cannot be unconditionally determined because they vary depending on the electrolytic solution used, but generally the concentration of the electrolytic solution is 1 to 80% by weight, and the liquid temperature is 5 to 70%.
C, current density 0.5-60 amps / dm ² , voltage 1-10
A range of 0 V and electrolysis time of 30 seconds to 50 minutes is suitable. Among these anodizing treatments, particularly British Patent No. 1,412,76
US Pat.
The method of anodic oxidation using phosphoric acid as an electrolytic bath described in 3,511,661 is preferable.

The aluminum plate which has been surface-roughened and anodized as described above may be subjected to a hydrophilic treatment if necessary, and a preferable example thereof is US Pat. No. 2,714,066.
Alkali metal silicates such as those disclosed in U.S. Pat. No. 3,181,461, such as aqueous sodium silicate or potassium fluorozirconate disclosed in Japanese Patent Publication No. 36-22063, and U.S. Pat. No. 4,153,461. There is a method of treating with polyvinylphosphonic acid as described above.

Further, an undercoat layer made of a water-soluble compound can be provided on the aluminum plate which has been roughened, anodized, and optionally hydrophilized as described above. As an example of such a water-soluble compound, JP-B-57
No. -16349, a combination of a water-soluble metal salt and hydrophilic cellulose (for example, zinc chloride and carboxymethyl cellulose, magnesium chloride and hydroxyethyl cellulose, etc.), polyacryal as disclosed in US Pat. No. 3,511,661. Mido, Special Public Sho-46-35
Polyvinylphosphonic acid disclosed in Japanese Patent No. 685,
Amino acids and salts thereof disclosed in JP-A-60-149491 (alkali metal salts such as Na salt and K salt, ammonium salts, hydrochlorides, oxalates, acetates, phosphates, etc.),
Hydroxyl group-containing amines and salts thereof (hydrochloride, oxalate, phosphate, etc.) disclosed in JP-A-60-232998, amino groups and phosphones disclosed in JP-A-63-165183. Compounds having an acid group or salts thereof, Japanese Patent Application Nos. 2-265845 and 3-10
Examples thereof include phosphonic acid, phosphinic acid, and phosphoric acid esters described in No. 604. Such water-soluble primer layer compounds preferably provided in the range of 1mg / m ² ~150mg / m ² in solids.

These compounds may be used in combination of two or more, and may optionally contain other compounds such as fine particles of silica and titanium dioxide, or dyes for the purpose of preventing halation.

[0017]

[Photosensitive layer] A photosensitive layer is provided on the lithographic printing plate support thus treated. The photosensitive composition constituting the photosensitive layer is one whose solubility or swelling property in a developing solution changes before and after exposure, and some typical examples will be described below. A. Positive-type photosensitive composition Composition comprising o-quinonediazide The photosensitive compound of the positive-type photosensitive composition includes an o-quinonediazide compound, and a representative example thereof is an o-naphthoquinonediazide compound.

The o-naphthoquinonediazide compound is
1, 2 described in JP-B-43-28403
-Esters of diazonaphthoquinone sulfonic acid chloride and pyrogallol-acetone resin are preferred. Other suitable orthoquinonediazide compounds include 1,2-diazonaphthoquinone-containing compounds described in U.S. Patent Nos. 3,046,120 and 3,188,210.
There are esters of 5-sulfonic acid chloride and phenol-formaldehyde resin, and they are disclosed in JP-A-2-96163, JP-A-2-96165, and JP-A-2-9676.
There is an ester of 1,2-diazonaphthoquinone-4-sulfonic acid chloride and a phenol-formaldehyde resin described in JP-A-1. Other useful o-naphthoquinonediazide compounds include those reported and known in numerous patents. For example, JP-A 47-5303, 48-63802, 48-
63803, 48-96575, 49-387.
No. 01, No. 48-13354, Japanese Patent Publication No. 37-1801
No. 5, No. 41-11222, No. 45-9610, No. 49-17481, U.S. Patent Nos. 2,797,213, 3,454,400, 3,544,323, and 3,573,917.
No. 3,674,495, No. 3,785,825, British Patent No.
1,227,602, 1,251,345, 1,267,005,
No. 1,329,888, No. 1,330,932, German Patent No. 85
The items described in each specification such as 4,890 can be cited.

When synthesizing these o-naphthoquinonediazide compounds, it is preferable to react 0.2-1.2 equivalents of 1,2-diazonaphthoquinonesulfonic acid chloride with respect to the hydroxy group of the polyhydroxy compound. 0.3 ~
It is more preferable to react 1.0 equivalent. 1,2-diazonaphthoquinonesulfonic acid chloride includes 1,2-
Diazonaphthoquinone-5-sulfonic acid chloride or 1,2-diazonaphthoquinone-4-sulfonic acid chloride can be used.

The o-quinonediazide compound alone constitutes the photosensitive layer, but it is preferable to use a resin soluble in alkaline water as a binder together with this type of resin. As such a resin soluble in alkaline water, there is a novolak resin having this property, such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, o-cresol formaldehyde resin, m- / p-.
Mixed cresol formaldehyde resin, phenol / cresol (m-, p-, o- or m- / p-, m- / o
A mixed formaldehyde resin such as cresol formaldehyde resin. In addition, resol-type phenolic resins are also preferably used, and phenol / cresol (m-, p-, o- or m- / p-, m- / o-mixed) mixed formaldehyde resin is preferable. In particular, JP-A-61-1
Phenolic resins described in Japanese Patent No. 217034 are preferable.

Further, phenol-modified xylene resin, polyhydroxystyrene, polyhalogenated hydroxystyrene, an acrylic resin containing a phenolic hydroxyl group as disclosed in JP-A-51-34711, JP-A-2-866. It is also possible to use various alkali-soluble polymer compounds such as an acrylic resin having a sulfonamide group described in No. 1, a urethane resin, and the like. These alkali-soluble polymer compounds have a weight average molecular weight of 50.
Those having a number average molecular weight of 0 to 2,000,000 and a number average molecular weight of 200 to 60,000 are preferable.

The alkali-soluble polymer compound is 1
One kind or a combination of two or more kinds may be used, and it is used in an amount of 80% by weight or less of the total composition. Furthermore,
As described in US Pat. No. 4,123,279, a condensate of formaldehyde with a phenol having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenolformaldehyde resin and octylphenolformaldehyde resin, is used in combination. It is preferable to improve the oil sensitivity of the image.

It is preferable to add cyclic acid anhydrides, phenols and organic acids to the photosensitive composition comprising o-quinonediazide in order to enhance sensitivity. Further, in order to increase the latitude of development, JP-A-62-2517 is used.
40 and non-ionic surfactants described in Japanese Patent Application No. 2-181248, JP-A-59-59
Amphoteric surfactants such as those described in Japanese Patent No. 121044 and Japanese Patent Application No. 2-115992 can be added. Further, a print-out agent for obtaining a visible image immediately after exposure, a dye as an image colorant, or other filler can be added. B. Negative-type photosensitive composition (B-1) Composition composed of diazo resin The diazo resin represented by the condensate of p-diazodiphenylamine and paraformaldehyde may be water-soluble or water-insoluble. Preferably, those which are insoluble in water and soluble in common organic solvents are used. Particularly preferred diazo compounds are compounds having two or more diazo groups in one molecule such as a condensate of p-diazodiphenylamine and formaldehyde or acetaldehyde, for example, a salt with phenol, a salt with sulfonic acid and the like. is there. The diazo resin may be used alone, but is preferably used together with a binder. Since various polymer compounds are known as binders,
It can also be used for the present invention. The content of the binder in the photosensitive layer is about 40 to 95% by weight,
When the amount of the binder is large (that is, when the amount of the diazo resin is small), the photosensitivity is naturally large, but the stability with time is deteriorated. The optimum amount of binder is about 70-90% by weight
Is. (B-2) Composition consisting of o-quinonediazide The composition consisting of o-quinonediazide used as a positive-type photosensitive composition can be prepared by the process described in JP-A 1-078249. After heat treatment,
A negative image can be obtained by "exposing the entire surface and performing alkali development".

Suitable o-quinonediazide compounds used as such a negative photosensitive composition are:
Examples thereof include 2-benzoquinone-2-azido-4-sulfonic acid ester and 1,2-naphthoquinone-2-diazide-4-sulfonic acid esters. Further, in order to make it easier to invert to the negative type, it is desirable to add the organic bases disclosed in JP-A No. 1-078249. Otherwise, the same compound as the above-mentioned “composition comprising o-quinonediazide” is used as the positive photosensitive composition,
A suitable composition can be obtained.

Such a photosensitive composition is dissolved in a solvent which dissolves each of the above components and coated on a support. As the solvent used here, ethylene dichloride, cyclohexanone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, 1-methoxy-
2-propanol, 1-methoxy-2-propylacetate, toluene, ethyl acetate, methyl lactate, ethyl lactate, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, water, N-methylpyrrolidone, tetrahydrofurfuryl alcohol, acetone, diacetone alcohol , Methanol, ethanol, isopropanol, diethylene glycol dimethyl ether, etc., and these solvents may be used alone or as a mixture. The concentration (solid content) in the above components is 2 to 50% by weight.
Is. In addition, the coating amount is generally 0.5 ~
3.0 g / m ² is preferred. Although the photosensitivity increases as the coating amount decreases, the physical properties of the photosensitive film deteriorate. A surfactant for improving the coating property, for example, a fluorine-based surfactant as described in JP-A-62-170950 can be added to the photosensitive composition. The preferred addition amount is 0.01 to 1% by weight, and more preferably 0.05 to 0.5% by weight, based on the total photosensitive composition.

The surface of the photosensitive layer provided as described above shortens the time until the PS plate and the original image film are brought into close contact with each other during vacuum contact exposure, and prevents burning blur.
It is preferably matted. Specifically, JP-A-50
-125805, Japanese Patent Publication No. 57-6582, 61-
Examples thereof include a method of providing a mat layer as described in JP-A No. 28986 and a method of heat-fusing a solid powder as described in JP-B-62-62337.

[0027]

[Original film] The original film of the present invention is not only a so-called original film having a halftone image, but also a so-called sticking film in which the original film is attached to a transparent base film with a single-sided adhesive tape or a double-sided adhesive tape. Is also included. As the transparent base film, a film that substantially transmits light can be used, and a semi-transparent film that is mat-processed for the purpose of scattering light can also be used. (Hereinafter, when the original image film itself, which is not particularly a sticking film, is referred to, it is referred to as the original image film body.) The adhesion between the photosensitive layer of the PS plate and the original image film is usually the PS plate on a table made of a rubber sheet. Original film on top,
A pressure-bonded glass plate is placed on the pressure-sensitive glass plate, and the air between the rubber sheet and the pressure-bonded glass plate is discharged by a vacuum pump to make a vacuum state (hereinafter referred to as vacuuming).
The pressure-bonded glass plate is usually fitted with a frame of iron, aluminum, or the like so that it can be easily evacuated.

[0028]

[Plastic film] The present invention is characterized in that a plastic film that transmits actinic rays is provided between the original film and the pressure-bonded glass plate. The plastic film may be any one that is substantially transparent to actinic rays, and may include a matt, semi-transparent one. The material of the plastic film may be any material that substantially transmits actinic rays, such as polyester,
Fluorine resin such as polyvinyl chloride, polyvinylidene chloride, polyvinyl formal, polyvinyl butyral, polyvinyl thioether, polyvinyl carbazole, polystyrene, acrylic resin, polyethylene, polypropylene, polyvinyl fluoride, polyamide, polyimide, polyurethane, polysulfone, polyether, polycarbonate, Celluloid, cellophane, triacetyl cellulose, silicone resin, etc. can be mentioned. In addition, isoprene rubber, butyl rubber, acrylic rubber, silicone rubber,
Epichlorohydrin rubber, butadiene rubber, styrene-
Rubbers such as butadiene rubber may also be mentioned.

As the plastics, various copolymers and copolycondensates can be used. Examples thereof include vinyl chloride-vinyl acetate copolymers and ethylene-vinyl acetate copolymers. it can. Among these, preferable plastics include polyesters represented by polyethylene terephthalate, polyethylene, polypropylene, polyvinylidene chloride, triacetyl cellulose, acrylic resins such as polymethyl methacrylate, and the like.

Further, such plastics may be blended and used, or various plasticizers and other additives may be added and used. The thickness of the above-mentioned plastic film can be 3 μm to 3 mm.
If the thickness is thinner than this, it is difficult to handle such as wrinkles, and if the thickness is thicker than this, the transmission efficiency of actinic rays is low,
There is a drawback that the exposure time is too long. The preferred thickness is 20 μm to 1 mm, more preferably 50 μm
˜500 μm.

The plastic film may be used by stacking one or more sheets, but if the number of sheets is too large, the transmittance of actinic rays becomes low, which requires a long exposure time.
Work efficiency decreases. When a so-called sticking film obtained by sticking an original drawing film on a transparent base is used as the original drawing film, one to two plastic films are used.
When the cost film body is used without using the sticking film as the original image film, the number of the plastic film is preferably 1 to 3 and more preferably 2 Is.

The plastic film may be used simply by placing it on the original image film, but it is preferable from the viewpoint of work efficiency to attach the plastic film to the side of the pressure-bonded glass plate opposite to the light source of actinic rays, that is, the side of the original image film. Any method may be used, but for example, the ends of the plastic film may be attached with double-sided adhesive tape, the ends may be attached with single-sided adhesive tape such as cellophane tape, the ends or several places may be commercially available. How to stick with various adhesives of
Examples include a method of pressing the end portion with a plate-shaped metal fitting or the like and stopping it with a screw or the like.

[0033]

[Pressure-bonded glass plate] The material of the pressure-bonded glass plate in the present invention is preferably a normal glass of an inorganic material or a strengthened glass having increased strength, but a glass of an organic material represented by an acrylic resin can also be used. ..

[0034]

[Rubber Sheet] In the present invention, a PS plate, an original film, a plastic film, and a pressure-bonded glass plate are arranged in this order on a base made of a rubber sheet, and a vacuum is drawn to bring them into close contact with each other for exposure. Here, the rubber sheet of the "table made of rubber sheet" is such that the air between the pressure-bonded glass plate and the rubber sheet is discharged by a vacuum pump so that the distance between the pressure-bonded glass plate and the rubber sheet causes the rubber sheet to bend. The purpose is to bring the shrinkage, PS plate, original film, plastic film that transmits actinic rays, and pressure-bonded glass into close contact. Therefore, as long as it has such a function, a rubber sheet may be used as long as it is not a so-called natural or synthetic rubber as long as it is a rubber-like elastic material. It also includes sheets made of such materials.

A cardboard, a paper, a plastic film or the like may be inserted between the rubber sheet and the PS plate for the purpose of preventing the rubber sheet from getting dirty.

[0036]

[Exposure] The photosensitive layer of the PS plate and the original film are brought into close contact with each other as described above, and then exposed to actinic rays. As the exposure light source used for the exposure, one that emits light having a wavelength that the photosensitive layer of the PS plate is exposed to is used, and a fluorescent lamp, a carbon arc lamp, a mercury lamp, a metal halide lamp or the like can be used. Further, the light ray may be a light ray containing a lot of parallel lines as shown in JP-A-62-23126 or a scattered light.

The time from the start of evacuation to the start of exposure may be any time as long as the air between the PS plate and the original film is released and the two are brought into close contact with each other. In addition to falling, it is easy to get burned out. Therefore, the exposure is preferably started within 1 minute, more preferably within 10 seconds after the PS plate and the original film are brought into close contact with each other.

The exposure time of the PS plate varies depending on the type of light source, the illuminance of the actinic ray, the sensitivity of the PS plate, etc., and cannot be determined unconditionally, but it is usually 10 seconds to 5 minutes. The type of PS plate exposure apparatus suitable for the present invention may be any type as long as it adopts a vacuum adhesion method. For example, a horizontal baking frame described in pages 133 to 135 of “Basics of Printing and Printing and Actual Series 3, Plate Making” by Dai Nippon Ink Chemical Co., Ltd. Graphic Publishing Center, published by Printing Press Laboratory,
A vertical type baking frame, a rotary printer, a breeder, etc. are mentioned. Also, as described in Japanese Utility Model Publication No. 1-34180,
In order to improve the vacuuming efficiency, a rubber sheet having a structure of rolling with a squeegee roller from the back side, that is, the side opposite to the PS plate can also be preferably used.

[0039]

[Development] The PS plate thus exposed is subjected to a development treatment, if necessary, through post-heating, overall light exposure, etc., and rinsed with or without washing with water (eg, a special rinse liquid containing a surfactant). The one described in JP-A-55-115045 is preferable) and the rinse is performed. Next, if necessary, erase unnecessary images, and if necessary,
After performing a burning process to increase printing durability,
A planographic printing plate can be obtained by applying a desensitizing gum.

Washing with water after the above-mentioned development is carried out, for example, in JP-A-57-57.
It is advantageous to carry out with repeatedly used rinsing water as described in JP 158643. Further, it is advantageous to use the erasing liquid described in Japanese Patent Publication No. 2-13293 for the erasing process. Further, as the above-mentioned desensitizing gum, Japanese Patent Publication Nos. 62-16834 and 62-62.
-25118, JP-A Nos. 62-7595 and 62-8.
Those described in Japanese Patent Nos. 3194 and 62-11693 can be used.

[0041]

The lithographic printing plate produced using the present invention is
At the time of vacuum contact exposure, paper powder, a single-sided or double-sided adhesive tape for sticking between the original film and the PS plate, between the base film and the original film in the sticking film, and on the original film (the side opposite to the PS plate) Even if foreign matter such as the above enters, it is extremely unlikely that a burning blurring failure will occur, and the scrap rate will be greatly reduced.

The reason why the present invention exhibits the above-mentioned surprising effects is not clear, but a PS plate in which a photosensitive component is decomposed by exposure to generate nitrogen gas is considered as follows. .. When a PS plate is used in which the photosensitive material is decomposed to generate nitrogen gas when exposed to light, it is observed that the original image film around the foreign material floats up from the PS plate during the exposure by the usual exposure method. That is, when the method of the present invention is not used, the nitrogen gas generated by the exposure has a small adhesion pressure between the original image film and the PS plate, gathers in the peripheral portion of the foreign matter, and forms a gap between the original image film and the PS plate. It is presumed that burning blur occurs. On the other hand, in the exposure according to the method of the present invention, the flexibility of the plastic film is larger than that of the pressure-bonded glass plate, so that the pressure of adhesion between the original image film and the PS plate around the foreign matter is increased, and the plastic film is not easily bonded to other parts. It is considered that the pressure difference decreases, and the nitrogen gas generated by the exposure becomes difficult to collect. That is, it is presumed that it is difficult to form a gap between the original film and the PS plate, and the burning blur is reduced.

[0043]

EXAMPLES The present invention will be described in more detail based on the following examples. However, the present invention is not limited to these examples. In the examples,% is% by weight
Is shown. <Examples 1 to 7 and Comparative Example 1> An aluminum plate (material: 1050) having a thickness of 0.3 mm was washed with trichlene and degreased, and then the surface was grained using a nylon brush and a 400 mesh pumice-water suspension. And washed well with water. This plate was immersed in a 25% sodium hydroxide aqueous solution at 45 ° C. for 9 seconds for etching, washed with water, and further immersed in 20% nitric acid for 20 seconds and washed with water. At this time, the etching amount of the grained surface was about 3 g / m ² . Then this plate is 7%
A direct current anodic oxide film of 3 g / m ² was formed at a current density of 15 A / dm ^{2 using} sulfuric acid as an electrolytic solution, and then washed with water and dried.

The following photosensitive solution was applied to the aluminum plate thus treated and dried at 100 ° C. for 1 minute to obtain a positive PS plate. The coating amount after drying was 2.0 g / m ² . Photosensitive solution Ester compound of naphthoquinone-1,2-diazide-5-sulfonyl chloride and pyrogallol-acetone resin (Note) 0.90 g Cresol-formaldehyde resin 2.00 g t-Butylphenol-formaldehyde resin (Note) 05 g Naphthoquinone-1,2-diazide-4-sulfonic acid chloride 0.03 g 4- [PN- (P-hydroxybenzoyl) aminophenyl] -2,6-bis (trichloromethyl) -S-triazine 0.02g Tetrahydrophthalic anhydride ... 0.05g Victoria Pure Blue BOH (Hodogaya Chemical Co., Ltd.) ... 0.04g Megafac F-177 (Dainippon Ink and Chemicals Co., Ltd. fluorine surfactant) ... 0 0.006 g Methyl ethyl ketone 8 g Propylene glycol monomethyl ether 15 g Note What is described in Example 1 in U.S. Pat. No. 3,635,709 Note: What is described in U.S. Pat. No. 4,123,279 Furthermore, the acrylic copolymer polymer of Example 1 of JP-B No. 61-28986 According to the method of Example 1 of the patent, the aqueous liquid A was spray-coated on the photosensitive layer of the PS plate to form a matte layer. The positive PS plate thus produced was exposed by various exposure methods using a PS light with a horizontal frame (made by Kitamura Photograph Plate Manufacturing Co., Ltd.), and then an automatic processor made by Fuji Photo Film Co., Ltd. Development processing was carried out with Stablon 900D using a developer DP-4 (trade name) manufactured by the same company diluted 9 times with water. The vacuuming time in the exposure process is 1 minute, and the exposure time is 12μ on the plate.
It is the time when the fine line of m disappears and the fine line of 15 μm can be reproduced. The original film used was obtained by attaching the original film body with 50% halftone image to a colorless and transparent 100 μm polyethylene terephthalate film (hereinafter abbreviated as PET film) using a 100 μm double-sided adhesive tape. In the "film", a 100 μm thick single-sided adhesive tape is attached to the PS plate side of the original film body.

The degree of blurring caused by the double-sided adhesive tape and the single-sided adhesive tape of the original film is the degree of blurring, and the former is visually noticeable from A (good) to F (bad).
The rank is expressed by the distance from the edge of the tape to the non-blurred portion (the portion where the halftone dot area is normal). It should be noted that the ranks A to C of the degree of blurring are normally usable levels.

Table 1 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Original image film and pressure-bonded glass Exposure time Inserted into the plasties Double-sided adhesive Single-sided adhesive tape film Note 2) (sec) Tape (blur width) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━ Example 1 10 μm PET film (transparent) 80 A 1.6 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━ Example 2 100 μm PET film (transparent) 84 A 1.5 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━ Example 3 250 μm PET film (transparent) 90 A 1.5 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━ ━━━━━━━ Example 4 100 μm PET film (transparent) 90 A 1.5 mm 2 sheets ━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━ Example 5 100 μm PET film (translucent) 90 B 2.5 mm Note 1) 1 sheet ━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━ Example 6 100 μm polyethylene 88 A 1.5 mm film (transparent) ━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━ Example 7 100 μm polypropylene film (transparent) 88 A 1.5 mm 1 sheet ━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━ Comparative example 1 None 80 F 5.5 mm ━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━ Note 1) Matt Light transmittance at what is 70%
(The transmitted light has a large proportion of scattered light.) Note 2) The insertion method was performed by simply placing the plastic film on the original film.

From Table 1, it can be seen that the present invention has a remarkable effect on the bokeh and is excellent. <Examples 8 to 14 and Comparative Example 2> In Examples 1 to 7 and Comparative Example 1, an eye rotary printer RP311 (a rotary printer manufactured by Eye Graphic Co., Ltd.) was used instead of the PS light of the exposure apparatus. In the same manner as the method of inserting the plastic film between the original film and the pressure-sensitive glass plate, except that a method of attaching the double-sided adhesive tape to the end of the plastic film and adhering it to the original-image film side of the pressure-sensitive glass plate is used. A bokeh test was performed. The test results are shown in Table 2.

It can be seen from Table 2 that the effect of the present invention is great. Table 2 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Original image film and pressure-bonded glass Exposure time Bokeh Inserted between the boards Plastics Double-sided adhesive Single-sided adhesive tape Cook film (sec) Tape (blur width) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 8 10 μm PET film (transparent) 40 A 1.6 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 9 100 μm PET film (transparent) 43 A 1.7 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 10 250 μm PET film (transparent) 46 A 1.7 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━ Real Example 11 100 μm PET film (transparent) 47 A 1.7 mm 2 sheets ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 12 100 μm PET film (transparent) 51 A 1.7 mm 3 sheets ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━ Example 13 50 μm polyvinylidene chloride film (transparent) 42 A 1.7 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━ Example 14 50 μm triacetyl cellulose film (transparent) 42 A 1.7 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━ Comparative example 2 None 40 F 5.6 mm ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━ <Examples 15 to 1 And Comparative Example 3> Example 8-14 and Comparative Example 2, vertical full-automatic 殖版 machine PC-2 in place of the eye Rotary Printer RP311 exposure apparatus
44-A (manufactured by Dainippon Screen Mfg. Co., Ltd.) was used to perform a burning blur test in the same manner. The results are shown in Table 3.
Shown in. From Table 3, it can be seen that the present invention has a great effect even in the plate making machine.

[Table 3] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Original image film and pressure-bonded glass Exposure time Inserted into the plasties Double-sided adhesive Single-sided adhesive tape Cook film (sec) Tape (blur width) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━ Example 16 100 μm PET film (transparent) 25 A 1.6 mm 2 sheets ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━ Example 17 500 μm PET film (transparent) 35 B 2.1 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━ Comparative example 3 None 20 F 5.0 mm ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <Examples 18 to 20 and Comparative Example 4> In Examples 1 to 7 and Comparative Example 1, instead of the sticking film used as the original drawing film, the original drawing film main body without sticking was used. The bokeh blur test was carried out in substantially the same manner except that the PS plate side of which a single-sided adhesive tape having a thickness of 100 μm was attached was used.

The results are shown in Table 4. It can be seen from Table 4 that the present invention is effective as in the above-mentioned embodiment, but in particular,
It can be seen that a remarkable effect appears when the number of plastic films is two or more. Table 4 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Original film and pressure-bonded glass Exposure time Bokeh Inserted between the boards PLASTIC Single-sided adhesive tape film (second) (blurred width) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 18 100 μm PET film (transparent) 40 5.5 mm 1 sheet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 19 Same as above 2 pieces 43 1.5mm ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 20 Same as above 3 pieces 47 1.5mm ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Comparative Example 4 None 38 6.3 mm ━━━━ ━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 5, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

The plastic film may be used by stacking one or more sheets, but if the number of sheets is too large, the transmittance of actinic rays becomes low, which requires a long exposure time.
Work efficiency decreases. When a so-called sticking film obtained by sticking an original drawing film on a transparent base is used as the original drawing film, one to two plastic films are used.
Like is preferably used, more preferably one, without using the film pasting as original film, when using an original image film body, the plastic film is preferably three from one, more preferably, 2 It is a sheet.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0041

[Correction method] Change

[Correction content]

[0041]

The lithographic printing plate produced using the present invention is
At the time of vacuum contact exposure, paper powder, one-sided or double-sided adhesive for sticking between the original film and PS plate, between the base film and the main body of the sticking film, and on the original film (the side opposite to the PS plate) Even if foreign matter such as tape gets in, the burn-out blurring failure is extremely unlikely to occur, and the scrap rate is greatly reduced.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takuo Watanabe 4000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Fuji Shashin Film Co., Ltd.

Claims (2)

[Claims] 1. An exposure method in which a photosensitive lithographic printing plate, an original film, and a pressure-bonded glass plate are superposed in this order and contact-exposed, and a plastic film transmitting actinic rays is arranged between the pressure-bonded glass plate and the original film. A method for exposing a photosensitive lithographic printing plate, which comprises contact exposure. 2. A vacuum contact exposure apparatus, wherein an actinic ray transparent plastic film is attached to the surface of the pressure-bonded glass plate on the side of the original image film.