JPH06348039A - Photomechanical process for photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To obtain a planographic printing plate having high printing resistance by short-time processing. CONSTITUTION:A photosensitive planographic printing plate with a photosensitive layer contg. at least an o-quinonediazido compd. and an alkali-soluble resin on the substrate is imagewise exposed and developed and then at least the photosensitive layer is heated to 50-250 deg.C by irradiation with far IR including a component of >=2mum wavelength.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for making a photosensitive lithographic printing plate. More specifically, it relates to a novel burning treatment after the development treatment at the time of plate making of the positive photosensitive lithographic printing plate.

[0002]

2. Description of the Related Art Conventionally, in a positive-working photosensitive lithographic printing plate, a heat treatment called a burning treatment has been widely performed after the development treatment for the purpose of improving printing durability. This burning treatment is generally carried out by placing the plate after development treatment for several minutes or longer in an oven in an atmosphere of 200 to 250 ° C.
Has been done. By this treatment, the alkali-soluble resin (particularly novolac resin) which is a constituent of the positive photosensitive lithographic printing plate is cured, so that the mechanical strength of the plate is improved and the printing durability is improved.

[0003]

However, the burning treatment requires an oven at a high temperature of 200 to 250 ° C. capable of accommodating a large size (for example, Kikuzen plate) plate, and the treatment time is several minutes. There are problems such as the above and long. Since the processing time is longer than development processing and the like (for example, development processing takes 20 to 40 seconds), it is an obstacle to full automation of plate processing. That is, poor energy efficiency during heat treatment has been a problem.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that after the photosensitive lithographic printing plate is exposed and developed, it is subjected to a specific burning treatment for plate-making to improve productivity. The inventors have found that the method is a method for making a photosensitive lithographic printing plate having excellent printing durability and stability, and have reached the present invention.

That is, it is an object of the present invention to provide a method for making a photosensitive lithographic printing plate having a low cost which is excellent in energy efficiency during the burning process. Another object of the present invention is to provide a plate making method of a photosensitive lithographic printing plate which shortens the plate making time and is excellent in productivity. A further object of the present invention is to provide a method for making a photosensitive lithographic printing plate having excellent printing durability and stability.

Therefore, the object of the present invention is to perform image exposure and development treatment in a method for making a photosensitive lithographic printing plate having a photosensitive layer containing at least an o-quinonediazide compound and an alkali-soluble resin on a support. After 2
It is easily achieved by a method for making a photosensitive lithographic printing plate characterized by heating at least the photosensitive layer to 50 to 250 ° C. by irradiation with far infrared rays containing a wavelength component of μm or more.

The present invention will be described in detail below.
The photosensitive lithographic printing plate used in the present invention comprises a support having thereon a photosensitive layer containing at least an o-quinonediazide compound and an alkali-soluble resin. The support suitable for the photosensitive layer lithographic printing plate of the invention is not particularly limited as long as it is a dimensionally stable plate, and it can be preferably used. Examples of such a support include paper, plastic, and metal, but an aluminum plate is most preferably used.

When an aluminum plate is used as the support, surface treatment such as graining treatment, anodic oxidation treatment and, if necessary, sealing treatment is performed. A known method can be applied to these treatments. Examples of the graining treatment method include a mechanical method and an electrolytic etching method. Examples of mechanical methods include a ball polishing method, a brush polishing method, a liquid honing polishing method, and a buff polishing method. The above-mentioned various methods can be used alone or in combination depending on the composition of the aluminum plate. The method of electrolytic etching is preferable.

Electrolytic etching is performed using phosphoric acid, sulfuric acid, hydrochloric acid,
It is carried out in a bath in which inorganic acids such as nitric acid are used alone or in a mixture of two or more kinds. After the graining treatment, if necessary, desmut treatment is performed with an aqueous solution of alkali or acid to neutralize and wash with water. The anodizing treatment is performed by using a solution containing one or more kinds of sulfuric acid, chromic acid, oxalic acid, phosphoric acid, malonic acid, etc. as an electrolytic solution and electrolyzing with an aluminum plate as an anode. The amount of anodized film formed is 1 to 50 mg
/ Dm ² is suitable, preferably 10-40 mg / d
m ² . The amount of the anodic oxide film is, for example, a phosphoric acid chromic acid solution (phosphoric acid 85% solution: 35 ml
Chromium (VI) oxide: 20 g is dissolved in 1 liter of water to dissolve the oxide film, and the weight change of the plate before and after film dissolution is measured.

Specific examples of the sealing treatment include boiling water treatment, steam treatment, sodium silicate treatment, and dichromate aqueous solution treatment. In addition to this, the aluminum plate support may be subjected to an undercoating treatment with an aqueous solution of a water-soluble polymer compound or a metal salt such as fluorinated zirconic acid. In the present invention, a photosensitive layer is provided on the above-mentioned support.

The photosensitive composition used in the present invention is not particularly limited as long as it is a positive photosensitive composition containing an o-quinonediazide compound and an alkali-soluble resin. More specifically, the following are mentioned. In the present invention, the o-quinonediazide compound used is preferably a compound having an o-benzoquinonediazide group or an o-naphthoquinonediazide group, and particularly preferably a compound having an o-naphthoquinonediazide group. Examples of such quinonediazide compounds include those described in JP-A-2-143251.

In the present invention, the content of the quinonediazide compound is 5 to 6 with respect to the entire photosensitive composition excluding the solvent.
0% by weight is preferable, and particularly preferably 10 to 50% by weight.
Is. In the present invention, as the alkali-soluble resin used together with the quinonediazide compound, any resin that can be mainly used as a binder may be used, but a novolac resin or a vinyl-based polymer resin, US Pat.
1,257, polyamide resins, US Pat. No. 3,660,097, linear polyurethane resins, polyvinyl alcohol phthalated resins, bisphenol A and epichlorohydrin condensed epoxy resins. , Cellulose acetate, celluloses such as cellulose acetate phthalate, and the like,
Preferable examples include novolac resins, vinyl polymer resins and combinations thereof. Examples of such an alkali-soluble resin include those described in JP-A-2-143251. In the present invention, the content of the alkali-soluble resin is based on the total solid content of the photosensitive composition,
5 to 95% by weight is preferable, and 20 to 90 is particularly preferable.
% By weight.

Further, in the positive photosensitive composition containing the quinonediazide compound used in the present invention, a dye, a surfactant for imparting a leveling property, etc., and an ink receptivity are improved in order to improve the ink receptivity. The oil sensitizer, the exposed visible image agent for imparting the visible image property after exposure, and the like can be added. The above photosensitive composition is dissolved in a solvent that dissolves each of the above components, and a photosensitive lithographic printing plate can be formed, for example, by coating and drying this on a support surface. , Methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve,
Cellosolves such as ethyl cellosolve acetate, dimethylformamide, dimethylsulfoxide, dioxane,
Acetone, cyclohexanone, trichloroethylene, methyl ethyl ketone, methyl carbitol, methyl lactate,
Examples thereof include diethylene glycol dimethyl ether. These solvents may be used alone or in admixture of two or more.

The coating amount of the above-mentioned photosensitive composition varies depending on the use, but is generally 0.5 to 3.5 g / solid content.
A range of m ² is suitable. As a coating method, a generally known roll coater, slide hopper type coater, gravure coater, whaler coater, wire bar coater or the like can be used.

After the coating process, a drying process for drying the solvent is provided. In the plate-making method of the present invention, the photosensitive lithographic printing plate thus obtained is exposed to light and developed according to a conventional method, and then the plate surface is irradiated with far-infrared rays to form a plate.
A lithographic printing plate can be obtained by heating at 0 to 250 ° C. Conventionally, since the lithographic printing plate was placed in a high-temperature atmosphere to perform the burning treatment, it was heated not only from the photosensitive layer side but also from the support on the release surface, but far infrared irradiation as in the present invention. By performing the burning in (1), it is possible to heat only from the photosensitive layer side, so that it becomes possible to mainly heat only the photosensitive layer efficiently.

The far infrared ray used in the present invention is about 2 μm.
There is no particular limitation as long as it contains a wavelength component of m or more, but 1
It is preferable that the short wavelength component of μm or less is small,
Those that do not include the visible region (0.7 μm or less) are more preferable. When using those having a large number of wavelength components in the ultraviolet and visible regions, it is preferable to remove low wavelength components of 0.7 μm or less by using an optical filter or the like.

A ceramic far-infrared heater or the like can be cited as a preferred example of the device for generating far-infrared rays. The radiation amount distribution of each wavelength emitted from the ceramic far infrared heater changes depending on the surface temperature of the heater. Therefore, the surface temperature is generally selected from the range of 100 to 1000 ° C, more preferably 200 to 800 ° C.
The shape of the irradiation source is not particularly limited, and may be, for example, a panel shape, a tubular shape, or a lamp shape. Considering energy efficiency, it is preferable to provide a reflector on the back surface of the irradiation source.

The irradiation method may be any method as long as it can irradiate the entire surface of the plate, and it is particularly preferable that the entire surface can be uniformly irradiated. In the case of the usual ceramic far-infrared heater described above, the irradiation source is at a distance of 1 m to 2 cm from the plate surface, preferably within 80 cm, more preferably within 60 cm, and the irradiation time is preferably within 1 to 60 seconds.

These conditions have different heat capacities depending on the film thickness of the plate and the amount of heat generation depending on the composition of the photosensitive layer, and therefore cannot be defined uniformly, but at least the plate surface temperature is 50 to 25.
It can be appropriately selected depending on the apparatus used so as to be 0 ° C. The plate surface temperature is not particularly limited as long as it falls within the above range, but from the viewpoint of productivity, it is preferably 100 ° C. or higher,
More preferably, it is 150 ° C. or higher. For example, if the distance between the irradiation source and the plate surface is long, the irradiation time needs to be long, and if the heater surface temperature is low, the irradiation time needs to be long. Further, if the size, number and output of the heaters are small, it is necessary to lengthen the irradiation time accordingly. However, irradiation for a long time may cause problems such as decomposition of the photosensitive compound and increase in equipment cost. Further, if the plate surface temperature is also high, the irradiation time can be shortened, but if the temperature is too high, problems such as decomposition of the photosensitive layer occur, so it is necessary to set the temperature to 250 ° C. or lower. Further, the irradiation method may be a batch method in which it is processed one by one, or a method in which it is processed continuously using a belt conveyor or the like.

[0020]

[Examples 1 to 3 and Comparative Examples 1 to 2]

(Preparation of planographic printing plate) An aluminum plate (material 1050, temper H16) having a thickness of 0.24 mm was degreased in a 5 wt% sodium hydroxide aqueous solution for 1 minute, and then 0.5 mol / liter of hydrochloric acid was added. The electrolytic etching treatment was performed in an aqueous solution under the conditions of temperature: 25 ° C., current density: 60 A / dm ² , treatment time: 30 seconds. Then, desmutting treatment was performed at 60 ° C. for 10 seconds in a 5 wt% sodium hydroxide aqueous solution. Then, anodization treatment was performed in a 20% sulfuric acid solution under the conditions of temperature: 20 ° C., current density: 3 A / dm ² , treatment time: 1 minute. Furthermore, hot water sealing treatment was performed for 20 seconds with hot water at 80 ° C. to prepare an aluminum plate as a lithographic printing plate support.

A coating solution prepared by dissolving a photosensitive composition having the following composition in methylcellosolve so as to have a solid content concentration of 12% by weight was applied to the above-mentioned aluminum plate by a spin coating method for 22.6 m.
It was coated so as to be g / dm ² and dried at 90 ° C. for 4 minutes to obtain a positive photosensitive lithographic printing plate. (Coating liquid of photosensitive composition)

[0022]

[Table 1] Naphthoquinone (1,2) -diazide- (2) -4-sulfonyl chloride and pyrogallol-acetone resin (Mw
= 2000) esterification product (condensation rate 30%) ...
15 parts-Phenol and m-, p-mixed cresol (20: 4
8:32 weight ratio) and co-polycondensation resin of formaldehyde (“SK-156” manufactured by Sumitomo Duren Co., Ltd.) …… 85 parts ・ Victoria Pure Blue BOH (Hodogaya Chemical Co., Ltd. dye) …… 0.8 parts An ester compound of a novolak resin (Mw = 1800) synthesized from p-tert-octylphenol and formaldehyde and naphthoquinone- (1,2) -diazide- (2) -5-sulfonic acid chloride (condensation rate 50
%) ...... 1 part 4- (p-dimethylaminophenyl) -6- (trichloromethyl) -s-triazine ...... 1 part cis-1,2-cyclohexanedicarboxylic acid ...... 2
Department

1 k of the photosensitive lithographic printing plate thus obtained
w A metal halide lamp (“Idle 2000” manufactured by Iwasaki Electric Co., Ltd.) is used as a light source and 400 through a positive transparent original image.
Exposure at mJ / cm ² and developer "SDR" manufactured by Konica Corporation
The plate was developed with a 6-fold diluted solution of "-1" at 25 ° C for 45 seconds.

(Examples 1 to 3) Subsequently, the planographic printing plate was irradiated with the far-infrared irradiation device shown below under the conditions shown in Table 1. The irradiation time in the table is the time when the leading edge of the plate passes between the nip rollers on one side to enter the irradiation surface, passes between the other nip rollers, and exits from the irradiation surface. The far-infrared heater surface temperature was measured using a thermocouple embedded in the ceramic heater in advance.

(Far-infrared irradiation device) Infrastein far-infrared ceramic heater manufactured by Nippon Insulators Co., Ltd.
A rectangle of 25 mm x 65 mm and 300 W) is vertically (125
10 units in the mm side direction, 10 in the horizontal direction (65 mm side direction)
A far-infrared irradiation source having 100 bodies arranged was prepared. Electric power was supplied to each heater at 200V up to 300W, and the heater temperature was adjusted using a variable resistor. Further, the surface of the irradiation source was set horizontally (the irradiation surface was downward), and the irradiation surface was made to convey the plate horizontally. If something other than the plate comes into contact with the plate on the irradiation surface, the heat capacity increases and the generated heat is taken away, which is not preferable. Therefore, in practice, two sets of powered nip rollers (length 1 m) were provided in the long side direction of the irradiation surface to hold down the plate. Between the two pairs of nip rollers, aluminum rods having a width of 20 mm were passed on both sides of the plate to form guide rails. The power of this nip roller can change the conveying speed and adjust the irradiation time. The distance between the irradiation surfaces was adjusted by moving the irradiation source up and down.

[0026]

[Table 2]

Each lithographic printing plate obtained as described above was printed by a "Heidelberg GTO" printing machine, and the number of printed sheets was measured. The printing durability is indicated by the number of sheets at which the solid portion starts to fade. These results are shown in the column of the number of printable sheets in Table-1.

(Comparative Examples 1 and 2) As comparative examples, lithographic printing plates were prepared by placing them in an oven under the conditions shown in Table 1 and performing a burning treatment. Further, the printing durability of these lithographic printing plates was carried out in the same manner as in the examples. The results are shown in the column for the number of printable sheets in Table-1. In Comparative Example 1, a printing durability equivalent to that of the far-infrared irradiation sample of the present invention was shown, but a processing time was overwhelmingly required as compared with the far-infrared irradiation processing of the present invention. Further, in Comparative Example 2, the burning treatment was performed for the same processing time as in Example 2 or 3, but the printing durability was extremely inferior to that in Example.

[0029]

EFFECT OF THE INVENTION By using the method for making a photosensitive lithographic printing plate according to the present invention, a lithographic printing plate having high printing durability can be obtained in a very short time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Hiroshi Fuyasu, 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Co., Ltd.

Claims (1)

[Claims] 1. A method for making a photosensitive lithographic printing plate having a photosensitive layer containing at least an o-quinonediazide compound and an alkali-soluble resin on a support, wherein a wavelength component of 2 μm or more is exposed after image exposure and development treatment. A method for making a photosensitive lithographic printing plate, which comprises heating at least the photosensitive layer to 50 to 250 ° C. by irradiation with far infrared rays.