JPH0356624B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lithographic printing original plate that does not require dampening water and is imparted with printout properties by exposure to light.

(Prior art) Quinonediazide compounds are one of the most widely used photosensitive materials due to their high photoreactivity, and they are also used as photosensitive layers in lithographic printing plates that do not require dampening water and have a silicone rubber layer as an ink repellent layer. The use of quinonediazide compounds is widely known.

Among them, an example disclosed in JP-A-55-59466 is a dampening solution in which a silicone rubber layer is provided via an adhesive layer on a photo-solubilizable photosensitive layer made of a quinonediazide compound, which is lined with an aluminum plate. An unnecessary lithographic printing plate has been proposed. Also, JP-A-55-
110249 proposes a lithographic printing plate that does not require dampening water and has a silicone rubber layer containing an adhesive component on a photo-soluble photosensitive layer made of a quinone diazide compound backed by an aluminum plate. . Furthermore, in an example disclosed in JP-A-56-80046, silicone is coated on a photosensitive layer in which a partially esterified product of naphthoquinone-1,2-diazide-5-sulfonic acid chloride and phenol novolac resin is crosslinked with a polyfunctional isocyanate. A lithographic printing plate that does not require dampening water and has a rubber layer has been proposed.

However, these lithographic printing original plates that do not require dampening water have the following drawbacks.

In other words, when a photosensitive layer containing a yellow-colored quinonediazide compound is exposed to light, it fades and becomes a pale yellow photosensitive layer, but under the yellow lamp used for exposure work, exposed areas and unexposed areas cannot be distinguished after exposure. It is difficult to do so. For this reason, in the multi-sided printing operation or printout operation in which one original image is printed many times side by side using a printing press during exposure work, it often results in erroneous operations such as multiple printing, due to the lack of image printout properties. This will significantly reduce workability.

(Objective of the invention) It is an object of the present invention to obtain a lithographic printing original plate that does not require dampening water and produces a clear printout image even under a yellow light upon exposure.

(Structure of the Invention) The present invention provides a lithographic printing original plate that does not require dampening water, which comprises a support, a photosensitive layer containing a quinonediazide compound, and a silicone rubber layer, which are laminated in this order.
The present invention is a lithographic printing original plate that does not require dampening water and is characterized in that the photosensitive layer contains a fluoran compound.

The fluoran compounds used in the present invention include all compounds that interact with the photodegradable components of the quinonediazide compound to develop other colors.

For example, the following compounds are particularly effective.
3-diethylamino-6-methylfluorane, 3
-diethylamino-6,8-dimethylfluorane, 3-diethylamino-5-methyl-7-t-
Butylfluorane, 3-diethylamino-7-aminofluorane, 3-N,N-diethylamino-7
-Methylaminofluorane, 3-diethylamino-7-cyclohexylaminofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino -6-
Methyl-7-p-butylanilinofluorane, 3
-diethylamino-7-N-cyclohexyl-N
-benzylaminofluorane, 3-diethylamino-7-chloroanilinofluorane, 3-diethylamino-6-methyl-7-p-phenetidinofluorane, 3-diethylamino-7(2-carbomethoxyanilino)fluorane , 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3,6
-dimethoxyfluorane, 4-benzylamino-
8-diethylamino-benzo[a]fluorane,
2-Amino-8-diethylaminobenzo[a]fluoran, 3-diethylaminobenzo[a]fluoran, 10-diethylaminobenzo[c]fluoran.

The amount of the fluoran compound used is effectively 1 to 30% by weight, most preferably 2 to 15% by weight, based on the photosensitive compound in the photosensitive layer.

If it is less than 1% by weight, the printout image will be weak due to exposure and will have little effect.

If it exceeds 30% by weight, it is disadvantageous for image reproducibility.

The support used in the present invention is not particularly limited, but any support that is used in ordinary planographic printing plates that do not require dampening water or that has been proposed may be used.

Examples include metal plates such as aluminum, iron, and zinc; transparent or opaque plastic films such as polyester, polyolefin, and polystyrene; and composites of both. It is also possible to provide a support by further coating these sheets for antihalation purposes and other purposes.

The quinonediazide compound used in the photosensitive layer of the present invention includes, for example, quinonediazides that are normally used in positive-working PS plates, Wipon plates, photoresists, and the like. As a specific compound,
For example, esters of benzoquinone-1,2-diazide-4- or -5-sulfonic acid and polyhydroxyphenyl, esters of naphthoquinone-1,2-diazide-4- or -5-sulfonic acid and pyrogallolacetone resin, naphthoquinone-1,2
Examples include esters of -diazide-4 or -5-sulfonic acid and phenol formaldehyde novolak resin, and reaction products of quinone 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 and phenol formaldehyde novolak resin.

It is also possible to add other components to the photosensitive layer for the purpose of improving coating film forming properties and adhesion to the support within a range that does not impair the effects of the present invention.

The composition for forming the above-mentioned photosensitive layer can be prepared using a suitable organic solvent (for example, dioxane, tetrahydrofuran, cellosolve, cellosolve acetate,
DMF, etc.).

The thickness of the photosensitive layer is 0.1~100μ, more preferably 0.5
~30μ is chosen. If it is too thin, pinholes are likely to occur in the photosensitive layer, while if it is too thick, it is economically disadvantageous, so the above range is preferable.

The silicone rubber layer used in the present invention usually has as a main component a linear organic polysiloxane having the following repeating units and having a molecular weight of several thousand to several hundred thousand.

Here, n is an integer of 2 or more, R is an alkyl group, alkenyl group, or phenyl group having 1 to 10 carbon atoms, and preferably 60% or more of R is a methyl group. Such a linear organic polysiloxane is sparsely crosslinked to form a silicone rubber. Therefore, a crosslinking agent is added to the linear organic polysiloxane.

Crosslinking agents include acetoxysilane, ketoxime silane, alkoxysilane, aminosilane, amidosilane, etc., which are used in so-called room temperature (low temperature) curing silicone rubber, and are usually linear organic polysiloxanes with hydroxyl groups at the ends. In combination, these silicone rubbers become deacetic acid type, oxime type, alcohol deal type, deamine type, and deamid type silicone rubber, respectively. Generally, a small amount of an organic tin compound or the like is further added as a catalyst to these silicone rubbers.

The appropriate thickness of the silicone rubber layer is about 0.5 to 100μ, preferably about 0.5 to 30μ.If it is too thin, problems may occur in terms of printing durability and ink repellency, while if it is too thick, it is not economical. Not only is this disadvantageous, but it also becomes difficult to remove the silicone rubber layer during development, resulting in a decrease in image reproducibility.

In the lithographic printing original plate that does not require dampening water of the present invention, the adhesion between the support and the photosensitive layer, and between the photosensitive layer and the silicone rubber layer is very important for basic plate performance such as image reproducibility and printing durability. Therefore, an adhesive layer may be provided between each layer or an adhesive component may be added to each layer as necessary. In particular, for adhesion between the photosensitive layer and the silicone rubber layer, a known silicone primer, silane coupling agent, or titanate coupling agent layer may be provided between the layers.
It is effective to add a silicone primer, a silane coupling agent, or a titanate coupling agent to the silicone rubber layer or photosensitive layer.

It is also possible to laminate a thin protective film on the surface of the silicone rubber layer forming the surface of the dampening water-free lithographic printing original plate constructed as described above.

As explained above, the dampening water-free lithographic printing original plate of the present invention is produced, for example, as follows.

First, on the support, reverse roll coater,
Using an ordinary coater such as an air knife coater or a Meyer bar coater or a rotary coating device such as a Whaler, the composition solution to form the photosensitive layer is coated, dried, and heat cured as necessary, after which the photosensitive layer is coated. An adhesive layer is applied on top using the same method, and after drying, a silicone rubber solution is applied on the photosensitive layer or adhesive layer using the same method, and is heat-treated for several minutes at a temperature of usually 60 to 130°C to fully cure it. to form a silicone rubber layer. If necessary, a protective film is laminated onto the silicone rubber layer using a laminator or the like.

For example, if a light-transmitting protective film is attached to the lithographic printing original plate manufactured in this way that does not require dampening water, it may be removed as is, or if a protective film with poor light-transmitting properties is attached, it may be removed. exposed to actinic light through a negative film sealed in vacuum. The light source used in this exposure process is one that generates abundant ultraviolet light, and can be a mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, or the like.

Next, if there is a protective film, remove it and rub the plate surface with a developing pad containing a developer to remove at least the silicone rubber layer in the image area, creating a printing plate with the photosensitive layer or the surface of the support exposed as the ink receiving area. is obtained.

The developing solution used in the present invention includes aliphatic hydrocarbons (hexane, heptane, gasoline, kerosene, etc.), aromatic hydrocarbons (toluene,
Xylene, etc.) to which the following polar solvents or a polar solvent and water are added are suitable.

Alcohols (methanol, ethanol, etc.) Ethers (ethyl cellosolve, methyl carbitol, etc.) Ketones (acetone, methyl ethyl ketone, etc.) Esters (methyl cellosolub acetate, acetic carbitol, etc.) In the present invention, quinonediazide compounds are included. By adding a fluoran compound to the photosensitive layer, a clear printout image can be produced even under yellow light by exposure alone, which improves workability when using a photocopier, and has significant effects such as eliminating operational errors. There is.

Furthermore, according to the present invention, storage stability is good despite using a printout agent,
Storing the printed version (raw version) for a long period of time (e.g. over 1 year)
Even when used as a printing plate later, it is possible to reliably obtain a lithographic printing original plate that does not require dampening water and has well-balanced practical performance such as good print-out properties, good image reproducibility, and storage stability of a raw plate.

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

Example 1, Comparative Example 1 The following photosensitive layer composition was spin-coated on a chemically treated aluminum plate (manufactured by Sumitomo Light Metals) with a thickness of 0.24 mm, and heated at 110°C.
Heat treatment was performed for 2 minutes to form a photosensitive layer with a thickness of 1.8 μm.

(a) 100 parts of naphthoquinone-1,2diazide-5-sulfonic acid ester of phenol novolak resin (Sumilite Resin PR50235, manufactured by Sumitomo Duress) with a degree of esterification of 48% (b) 3-diethylamino-6-methyl-7 -Anilinofluorane 5 parts (c) Dioxane 2000 parts Next, a silicone rubber composition having the composition shown below was spin-coated on top of this, and then cured by heating at 120°C with a dew point of 30°C for 3.5 minutes to obtain a silicone rubber with a thickness of 2.5μ. Layers were set up.

(a) Dimethylpolysiloxane (molecular weight 25,000, terminal hydroxyl group) 100 parts (b) Vinyltrimethylethylketoxime silane
8 parts (c) Dibutyltin diacetate 0.1 part (d) γ-Aminopropyltrimethoxysilane 2 parts (e) Isopar E 1500 parts A negative film was vacuum-adhered to the printing original plate obtained as above, and a 2Kw metal halide lamp was used.
Exposure was carried out for 60 seconds from a distance of 1 m.

The exposed areas were colored blue-black, and the unexposed areas remained pale yellow. This exposed printing master had a printout image with sufficient contrast that unexposed areas and exposed areas could be clearly distinguished in all details under yellow light.

On the other hand, when a printing original plate obtained in the same manner except that 3-diethylamino-6-methyl-7-anilinofluorane was removed from the photosensitive layer composition described above was exposed in the same manner, the exposed areas were The contrast between the image and the unexposed area was weak, especially under yellow light, making the printed image almost indistinguishable.

Next, this exposed printing original plate is lightly rubbed with a developer pad impregnated with a developer having a composition of Isopa-E/ethanol (80/20 weight ratio) to remove the silicone rubber layer and photosensitive layer in the exposed areas. A printing plate that faithfully reproduced the negative film image was obtained.

When this printing plate was attached to an offset printing machine (Komori Sprint 2 Color) and printing was performed without using dampening water, good printed matter was obtained.

Example 2 A 0.24 mm thick aluminum plate (manufactured by Sumitomo Light Metals) was coated with resol resin (Sumilight Resin PC-1, manufactured by Sumitomo Durez) to a thickness of 2 μm, and cured at 200° C. for 3 minutes to obtain a support. The following photosensitive layer composition was spin-coated onto this support and cured by heating at 120° C. for 1 minute to provide a photosensitive layer having a thickness of 2.0 μm.

(a) Naphthoquinone-1,2-diazide-5- of phenolic novolac resin (Sumilite Resin PR50235, manufactured by Sumitomo Duress) with a degree of esterification of 44%
Sulfonic acid ester 100 parts (b) 4,4'-diphenylmethane diisocyanate
30 parts (c) dibutyltin diacetate 0.2 parts (d) 3-diethylaminobenzo[a]fluorane
5 parts (e) 2500 parts of tetrahydrofuran Subsequently, the following silicone rubber composition was spin-coated thereon and cured by heating at 120°C and a dew point of 30°C for 3.5 minutes to form a silicone rubber layer with a thickness of 2.3μ.

(a) Dimethylpolysiloxane (molecular weight 25,000, terminal hydroxyl group) 100 parts (b) Vinyltrimethylethylketoxime silane
8 parts (c) dibutyltin diacetate 0.1 part (d) γ-aminopropyltrimethoxysilane
0.5 parts (e) 1450 parts of Isopar-E Subsequently, a polypropylene film (8μ) was laminated using a laminator.

The color of the printing original plate obtained as described above was pale yellow. A metal high-ride lamp 2k is passed through a negative film that is vacuum-adhered to this original printing plate.
Exposure was performed for 60 seconds from a distance of 1 m using m.

The exposed areas developed a blue-black color, and the unexposed areas remained pale yellow. Therefore, even under yellow light, exposed areas could be clearly distinguished from unexposed areas in all details.

Next, the exposed plate was placed on the printing frame, and the entire surface was exposed to light for 6 seconds at an illuminance of 11 mW/cm ² using the same lamp.

Subsequently, the polypropylene film was peeled off from this exposed printing original plate, and 1 part was added to a pretreatment solution of Isopar H/butyl carbitol/ethyl sesolve/monoethanolamine (90/5/5/0.2 weight ratio).
After soaking for minutes, then water/butyl carbitol/ethyl carbitol/2-ethyl butyric acid (70/
When a developer (15/15/2 weight ratio) was soaked into the pad and rubbed lightly, only the silicone rubber layer in the exposed areas was removed, yielding a printing plate that faithfully reproduced the negative film image.

Claims (1)

[Claims] 1. A dampening water-less lithographic printing original plate comprising a support, a photosensitive layer containing a quinonediazide compound, and a silicone rubber layer, which are laminated in this order, characterized in that the photosensitive layer contains a fluoran compound. Water-free lithographic printing original plate.