JPS60188947A - Water-free lithographic plate - Google Patents

Abstract

PURPOSE:To ensure printability having sufficient contrast immediately after exposure by incorporating a quinonediazide compd., a pH indicator, and a dye having a complementary color to the color of the pH indicator after color change in a photosensitive layer. CONSTITUTION:An intended water-free lithographic plate is obtained by mixing (A) a quinonediazide compd., such as polyhydroxydiphenyl benzoquinone-1,2- diazide-5-sulfonate, (B) a pH indicator changing in color in the pH range of 2.5- 6.5, such as methyl organe, (C) and a dye, such as malachite green oxalate, located in a complementary color region to the changed color of the indicator; coating a support with the photosensitive compsn. thus obtained to form a photosensitive layer; and further coating a silicone rubber layer on it. As a result, after exposure, a sharp printed image can be clearly confirmed under a yellow lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Differential Field of Application] The present invention relates to a waterless lithographic printing plate that is provided with printout properties.

[Prior art]

In conventional planographic printing using an offset method, the composition of the dampening water, the supply amount, etc., and the balance of the ink have a large influence on the printing results, so a very advanced technique is required for supplying the dampening water. For this reason, the offset printing industry has been eagerly awaiting the emergence of a so-called waterless lithographic printing plate that does not require dampening water.

In recent years, many proposals regarding waterless lithographic printing plates have been made to meet this requirement. For example, in the photosensitive layer, naphthoquinone-1,2-diazide-5 and 4-
A waterless lithographic printing plate using a novolak resin esterified with sulfonic acid was published in JP-A-55-5946.6.
It is disclosed in Japanese Patent Application Laid-Open No. 55-110249. However, these waterless planographic printing plates have the following drawbacks. Namely.

This yellow photosensitive resin fades after exposure and becomes a pale yellow photodegradable component, but under the yellow safety lights during exposure work, it is impossible to distinguish between exposed and unexposed areas after exposure, resulting in so-called printout. There is no sex. For this reason, in multi-sided printing operations in which a large plate is printed many times side by side, it may not be possible to confirm which areas have been exposed, or if the exposure operation is interrupted, I couldn't tell if it was the version or not. Furthermore, it is not possible to confirm whether a desired image has been printed at a predetermined position. This often leads to erroneous operations such as multiple printing, which is a cause of a significant decrease in work efficiency.

On the other hand, in the case of planographic materials that use ordinary water, the technology of imparting printout properties by using a pH indicator in conjunction with a plate material containing 〇-naphthoquinonediazide as a photosensitive component has been proposed since the 1970s.
This method is known from Japanese Patent Application Laid-open No. 0-21095 and Japanese Patent Application Laid-Open No. 58-87555. An attempt was made to apply this technique to the waterless planographic material of the present invention, but the contrast was insufficient and practical printability could not be obtained.

[Purpose of the invention]

In view of the above circumstances, the present inventors completed the present invention as a result of intensive research with the aim of developing a waterless lithographic printing plate that can obtain printout properties with sufficient contrast immediately after exposure. I ended up doing it.

[Structure of the Invention] That is, the present invention is a waterless lithographic printing plate comprising a photosensitive layer and a silicone rubber layer coated in this order on a support,
The present invention is a waterless lithographic printing plate characterized in that the photosensitive layer contains (&) a pH indicator that converts into quinonediazide, and (C) a dye having a complementary color range to the color of the pH indicator after color change.

The reason why waterless planographic printing having a photosensitive layer having the above composition as a main component has good printout properties is considered to be due to the following mechanism.

When exposed to light through, for example, a negative film having a desired pattern, the naphthoquinone diazide groups in the exposed portions undergo photodecomposition to become a compound having an indenecarboxylic acid structure. At this time, the pH in the photosensitive layer changes to the acidic side, and the pH
The indicator reacts to this and causes a color change. This changed p
Since the photosensitive layer is colored with a color in the complementary color range to the color of the H indicator, saturation is reduced and sufficient contrast is obtained.

It is thought that good print-out properties are imparted.

Of course, the color change of the pH indicator alone shows printout properties, but the contrast is small and the printout properties are insufficient.

The following two inventions will be explained in more detail.

The photosensitive layer used in the present invention is K (
It is a composition consisting of three components: a), (b), and (0). The quinonediazide compound (a) is a known compound commonly used in positive PS plates, Wipon plates, photoresists, etc. can be used.

Specific compounds include esters of benzoquinone-1,2-diazide-4 or 5-sulfonic acid and polyhydroxyphenyl, naphthoquinone-1,2-diazide-4
or 5-sulfone [ester with pyrogallol acetone resin, naphthoquinone-1,2-diazide-4t or 5
Examples include esters of -sulfonic acid and phenol formaldehyde novolak resin, and reaction products of chino/diazides and polyfunctional compounds as proposed in JP-A-56-80046.

A particularly preferred quinonediazide compound in the present invention is a partially esterified product of naphthoquinone-1,2-diazide-5-sulfonic acid tophenol formaldehyde noporac resin. A co-esterified product is also preferably used.

As component (b), a known pH indicator that changes color in the pH range of about 2.5 to about 6.5 is used. For example, metacresol purple, rosexylenol blue, thymol blue, troveolin 00. methyl violet,
Benzyl orange, methyl yellow, f-trabromophenol blue, bromophenol blue, Congo red, methyl orange, ethyl orange, alizarin red S, bromocresol green, methyl red, ethyl red, lachmoid, bromocresol purple.

Examples include bromophenol red and furomothymol blue. These pH indicators are used alone or in a mixture of two or more in an amount of 0.05 to 10 parts by weight per 100 parts by weight of the quinonediazide compound.

(c) Any dye can be selected that is in the complementary color range to the color of the pH indicator after the component changes color, but only one color is used.

Ai is considered from the perspective of the influence it has on human emotions and feelings.
Ichimu h8
It is preferable to select from dyes having a green to blue hue (edited by the Color Science Association, "Color Science Handbook" P291 (1962 edition), which gives calmness, etc.).Needless to say, the pH indicator selected in this case is It is selected from those whose exposed areas develop a color in the yellow-red to reddish-violet range, which is in the complementary color range to the green to blue range.The complementary color range used in the present invention is referred to here.

It means 6 hues including the complementary colors on both sides of the 10 hue circle according to the Munsell method. For example, for red, its complementary color blue-green and 1
Green and blue on both sides form the complementary color range.

These dyes have green to blue hues.

Selected from azo dyes, anthraquinone dyes, carbonium dyes, etc., amide dark green B, diamond green 5 (3, benzo sky blue, Chicago blue RW,
Diazo brilliant green 3B, alizarin blue S
, Alizarin Astrol B, Indanthrene Green BB, Hydron Blue 〇, Malachite Green, Patent Blue AF, Crystal Violet, Victoria Blue B, Cation Blue, Anthrazole Green IB
, Shiba Blue 2B, methylene blue and the like. These dyes are used alone or in a mixture of two or more in an amount of 0.05 to 10 parts by weight per 100 parts by weight of the quinonediazide compound.

The photosensitive resin of the present invention having the composition as described above is coated on a support as a photosensitive layer to a thickness of 0.5 to 50 μm. If it is too thin, it will cause pinholes, and if it is too thick, cracks will easily occur, and it will also be economically disadvantageous. To obtain coating properties and uniform bake-out properties when applying.

It is preferable to use a solution in which all six components (a), (b), and (c) are uniformly dissolved. It is also possible to add other components to the photosensitive layer in order to improve film forming properties and adhesion to the support or silicone rubber layer within a range that does not impair its performance.

The thickness of the silicone rubber layer used as the ink repellent layer of the present invention is 0.5 to 100 microns, preferably 1 to 50 microns. Useful silicone rubbers are:

It is a silicone rubber whose main component is a linear polysiloxane with a molecular weight of several thousand to several hundred thousand having such repeating units.

(R is preferably an alkyl group having 1 to 10 carbon atoms, a phenyl group, and a methyl group in which H has a coefficient of 60 or more.) The conolinear organopolysiloxane is preferably one having a terminal hydroxyl group, and an acetyl In the presence of a cross-linking agent such as silane, ketoxime silane, or alkoxysilane, cross-linking is performed by heat treatment in the presence of a catalyst such as an organic tin compound, and used as a silicone rubber layer.

If necessary, a known silicone primer or a silicone coupling agent layer may be provided between the nine layers for adhesion between the silicone rubber layer and the photosensitive layer or the photosensitive layer and the support. It is also effective to add a silicone primer or a silane coupling agent.

As the support, paper, plastic film or sheet, natural or synthetic rubber sheet, metal plate, etc. are used. These supports can be further provided with a coating layer or a lamination layer for the purpose of preventing nolation and other purposes, and can be used as a support.

The silicone rubber layer forming the surface of the lithographic printing plate constructed as described above may be laminated with a protective film in order to prevent the formation of scratches, adhesion of chips, etc. Useful protective films include polyethylene and polypropylene.

Examples include polyvinyl alcohol and polyethylene terephthalate.

A waterless lithographic printing plate according to the invention can be used, for example.

When the surface is rubbed with a developing pad such as a cloth, brush, or sponge impregnated with a developer, the photosensitive layer in the exposed area dissolves or swells, and the upper silicone rubber layer is easily peeled off to expose the support.

As a developer, it penetrates the silicone rubber layer.

A material that dissolves or swells only the exposed photosensitive layer is used. Examples of such a developer include Example 1: A 250μ polyethylene terephthalate film is coated with 250μ nitridoquinone-1 having a Shore A hardness of 7o,
A 2-diazide-5-sulfonic acid ene rubber layer was obtained.

(c) When rubbed with dibutyltin sheatate o, 2 parts by weight carpet''), an image faithful to the negative film with exposed nitrile rubber surface was obtained. Instead, 1.
0 parts by weight of methyl yellow and 1.5 parts by weight of Brimoji 7 instead of malachite green oxalate were used under the same conditions as in Example 1 to obtain a bright green printing plate. A clear printed image was obtained under a colored lamp. It could be clearly seen that polyethylene terephthalate was formed by development.

Example 3 A printed image could be clearly seen, and an image faithful to the negative film in which the surface of the nitrile rubber was exposed by development was obtained.

Example 4 A green printing original plate was obtained under the same conditions except that thymol blue of 1.0 parts by weight Ji was used in place of methyl orange in Example 1. Next, when exposed under the same conditions, a clear printout image could be clearly seen under a chromatic lamp, and by development an image faithful to the negative film with the surface of the nitrile rubber exposed was obtained.

Example 5 A chemically treated aluminum plate with a thickness of 0.24 mm was used as a support,
On top of this, the following photosensitive layer composition was spin coated and
It was cured by heating at °C for 1 minute to form a photosensitive layer with a thickness of 2.0 μm.

naphthoquinone-1,2-diazide-5-sulfonic acid ester of resin (ioo parts by weight) (b) 60 parts by weight of 4.4'-diphenylmethane diisocyanate (C) 0.2 parts by weight of dibutyltin diacetate (d)
Methyl Yellow 12 parts by weight (e) Victoria Blue BH (Hodogaya Chemical) 1.0
Part by weight (f) 2500 parts by weight of tetrahydrofuran Then, after spin-coating the silicone rubber composition below, 1
A silicone rubber layer having a thickness of 2.5 μm was provided by heating and curing for 3.5 minutes under moist heat at 20°C and a dew point of 30°C.

(a) Dimethylpolysiloxane (molecular weight approximately 60,000.

(terminal OH group) 100 parts by weight (b) Vinyltrimethyl(ethyl)ketoxime silane 8.0 parts by weight (c) Dibutyltin diacetate 01 parts by weight (d)
0.5 parts by weight of γ-aminopropyltrimethoxysilane (e) Isopar E, 1450 parts by weight The printing original plate obtained as above was dark green in color. Next, when exposure was performed under the same conditions as in Example 1, a clear printout image could be clearly seen under a yellow light.

Next, this exposed printing original plate was immersed for 1 minute in a pretreatment solution with a weight ratio of Tisovar-H7 olecarpitol/ethylseronulf/monoethanolamine-90151510, and then water/butylcalpitol/
Ethylcarpitol/2-ethylbutyric acid (70/15/1
When the pad was impregnated with a developing solution (5/2 weight ratio) and rubbed lightly, only the silicone rubber layer in the exposed areas was removed, and a printing plate that faithfully reproduced the negative film image was obtained.

Patent applicant Higashi Shikikai Co., Ltd.

Claims (1)

[Claims] A waterless lithographic printing plate comprising a photosensitive layer and a silicone rubber layer coated in this order on a support, the photosensitive layer comprising (a) a quinonediazide compound and (b) a pH range of about 2.5 to about 65. A waterless lithographic printing plate characterized by containing a pH indicator that changes color, and (c) a dye that is in a complementary color range to the color of the pH indicator after the color change.