JPH0225497B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for post-processing a lithographic printing plate that does not require dampening water and uses a silicone rubber layer as a non-image area, and particularly relates to a method for post-processing a lithographic printing plate that does not require dampening water, and in particular provides a non-adhesive material layer on the printing plate. The present invention relates to a method for post-processing a lithographic printing plate that does not require dampening water.

As a lithographic printing plate that does not require dampening water and uses a silicone rubber layer lined with a substrate as a non-image area, for example,
(A) As shown in JP-A-50-50102, JP-A-55-59466, JP-A-46-16044, etc., an image-forming material layer (photosensitive layer) is provided on a substrate, and an image-forming material layer (photosensitive layer) is provided on the substrate. Those with a silicone layer (silicone upper layer type),
(B) Image formation on a silicone rubber layer backed by a substrate, as in Japanese Patent Publication No. 44-23042, Japanese Patent Publication No. 47-2361, Japanese Patent Publication No. 49-82402, Japanese Patent Application Publication No. 50-16305, etc. Those provided with a material layer (photosensitive layer) (silicone lower layer type), (C) JP-A-49-68803, JP-A-49
-39200, etc., in which the silicone rubber layer backed by the substrate itself is imparted with photosensitivity and participates in image formation (single-layer silicone type) have been proposed.

Among these printing plates, (A) silicone upper layer type and
The silicone single-layer type shown in (C) is a so-called flat intaglio plate in which the image area is concave compared to the silicone rubber in the non-image area, and when printing with this type, it is not transferred to the printing material such as paper. It is thought that the film thickness of the ink corresponds to the depth of the recesses in the printing plate.

On the other hand, the silicone underlayer type printing plate (B) is a so-called planar relief plate in which the image area is convex with respect to the silicone rubber in the non-image area, and the film thickness of the ink transferred to paper or the like is small.

When trying to transfer a large thickness of ink onto paper using these printing plates, plano relief plates naturally have their limits, and plano intaglio plates require increasing the thickness of the silicone rubber layer and photosensitive layer to increase the depth of the recesses. Although it is effective to increase the size, there is a problem in that it is difficult to obtain a satisfactory image.

The present inventors have conducted intensive studies to improve these problems, and as a result, have arrived at the present invention.

That is, the present invention provides a lithographic printing plate that does not require dampening water and has a silicone rubber layer lined on a substrate as a non-image area, and after providing a non-adhesive material layer on the printing plate, The present invention relates to a method for post-processing a lithographic printing plate that does not require dampening water, characterized in that only the non-adhesive material layer is removed.

As the non-adhesive material of the present invention, silicone rubber that is said to be room temperature curing type or low temperature curing type is suitable, but high temperature curing silicone rubber, fluorine-based compounds, etc. can also be used, or several types of these can be mixed. It may also be used as

These silicone rubbers are mainly composed of linear organic polysiloxanes having the following repeating units.

(Here, R is an alkyl group having 1 to 10 carbon atoms, a phenyl group, or a vinyl group, preferably of which 60% or more is a methyl group.) Such linear organic polysiloxanes can be used with various crosslinking agents. are added, and each can be three-dimensionally crosslinked and cured to form a rubber. These silicone rubbers include one-component type and two-component type, and are classified as follows according to their curing mechanism.

One-component type 1 Condensation reaction type (1) Deacetic acid type (2) Deoxime type (3) Dealcoholization type (4) Deamination type (5) Deamidation type 2 Addition reaction type (1) Vinyl addition reaction type (2 ) Peroxide type two-component type 1 Condensation reaction type (1) Dealcoholization type (2) Deoxyamine type (3) Dehydrogenation type 2 Addition reaction type (1) Vinyl addition reaction type In addition, these curing reactions usually involve the use of various catalysts. is required, and metal compounds etc. are added.

The substrate of the lithographic printing plate that does not require dampening water of the present invention has a thickness of about 10μ to 2mm, preferably about 50μ to 2mm.
Suitable materials include 400 μm paper, plastic film or sheet, sheet of elastic material such as rubber, metal plate such as aluminum, and those subjected to various surface treatments, but a cylindrical substrate may also be used.

The silicone rubber layer used in the lithographic printing plate that does not require dampening water of the present invention has a thickness of about 0.5 to 100μ, preferably about
It has a thickness of 0.5 to 10 microns and is mainly composed of a linear organic polysiloxane with a molecular weight of several thousand to several hundred thousand having the following repeating units.

Here, n is an integer of 1 or more, and R is an alkyl group, alkenyl group, or phenyl group having 1 to 10 carbon atoms.

A crosslinking agent is usually added to this linear organic polysiloxane. Crosslinking agents used in so-called room temperature (low temperature) curing silicone rubber include acetoxysilane, ketoxime silane, alkoxysilane, aminosilane, amidosilane, etc., and are usually linear organic polysiloxanes with hydroxyl groups at the ends. When combined, they become deaceticated, oxime-free, alcohol-dealt, deamined, and deamidated silicone rubbers.

Moreover, these may be silicone rubber layers imparted with photosensitivity.

Examples of the configuration and image forming method of the printing plate of the present invention are as follows.

(1) An image-forming substance layer is provided on a silicone rubber layer backed by a substrate via an adhesive layer or the like. This is subjected to image exposure, and the image-forming material layer in the non-image area is developed and removed by utilizing the change in solubility, and the silicone rubber layer is exposed.
As the image forming substance, a known photosensitive substance such as a photocurable type or a photodegradable type is used.

(2) Those having a silicone rubber layer backed by a substrate with an image-forming substance layer interposed therebetween. An image is obtained by subjecting this to image exposure and removing the silicone rubber layer in the image area by development, or by simultaneously developing and removing the image-forming material layer in the image area and the silicone rubber layer thereon. As the image-forming substance, a known photosensitive substance such as a photocurable type or a photodegradable type is used.

(3) A silicone rubber layer with image-forming properties provided on a substrate.

(4) A silicone rubber layer is provided on a substrate, and an image is provided on the silicone rubber layer using an electrophotographic method or the like.

etc.

A method for providing a non-adhesive material layer on the plate surface of a lithographic printing plate that does not require dampening water and is prepared by the method described above includes, for example, applying a solution or dispersion of a non-adhesive material directly to the plate surface and drying it. Alternatively, a method may be used in which a non-adhesive material layer provided on a carrier film is transferred onto a printing plate, and if necessary, pressure and heat are applied.

The carrier film used here includes polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate, cellophane, ABS, polystyrene, nylon, etc. with a thickness of about 5 μ to 2 mm, preferably about 9 μ to 100 μ. Plastic film is suitable, but metal plates, paper, synthetic paper, etc. may also be used.

Furthermore, as a method for forming a silicone rubber layer as a non-adhesive material layer on the carrier film, an uncured silicone rubber solution is coated with a continuous coater such as a bar coater, gravure roll coater, reverse roll coater, or slit die coater. Then, it may be applied uniformly onto the film and heated at a required temperature for a required period of time to cause a curing reaction to form a non-adhesive material layer.

In the so-called flat intaglio printing plates having the configurations (2) and (3) above, the depth of the recesses in the image area is approximately 1 μ to approximately
10μ, and if it is deeper than this, a printing plate that is faithful to the original image cannot be obtained, but by the method of the present invention, it is about 0.5μ.
A printing plate with deep recesses in the image area can be obtained by providing a non-adhesive material layer of ~50μ, preferably about 1 to about 10μ, on the printing plate and removing only the non-adhesive material layer on the image area. .

In addition, in the so-called plano-relief-type planographic printing plates that do not require dampening water (1) and (4), the non-adhesive material layer is approximately 0.5 to 50μ, preferably approximately 1 to
A printing plate having deep recesses can be obtained by removing only the non-adhesive material layer, which is provided to a thickness of 10 μm and similarly provided on the image area, while leaving all or part of the image area.

The non-adhesive material layer of the present invention contains a known adhesion improver for the purpose of improving the adhesion with the silicone rubber layer which is the non-image area of the lithographic printing plate that does not require dampening water.
A silicone primer, a silane coupling agent, etc. may be added, and a non-adhesive material layer may be provided via an adhesion improver as described above.

After forming the non-adhesive material layer according to the method of the present invention, the method for removing the non-adhesive material layer on the image area is to lightly rub the plate surface using a developer as necessary. There are methods. The developer used at this time is mainly a hydrocarbon solvent containing polar solvents such as alcohols and esters as required.

In addition, when a non-adhesive material layer is provided by transfer from a carrier film, it may be removed using a developer in the same way, but the adhesiveness between the non-adhesive material and the silicone rubber layer in the non-image area Then, so-called peel-off development may be performed by utilizing the difference in adhesiveness between the non-adhesive substance and the image area.

The present invention will be explained in more detail with reference to Examples below.

Example 1 A commercially available "Toray waterless lithographic plate" original plate was subjected to image exposure in a conventional manner and then developed to obtain a lithographic printing plate that does not require dampening water. Next, silicone rubber “SH-781” manufactured by Toray Silicone Co., Ltd. was applied to the entire surface of this printing plate.
A solution of Isopar E (manufactured by Etsuo Kagaku) was applied so that the dry thickness was 7μ. 120℃ for this thing
After heat treatment for 3 minutes with
The silicone rubber layer above the image area was removed by rubbing lightly with absorbent cotton soaked with . At this time, the silicone rubber layer on the non-image area was firmly adhered to the printing plate and could not be removed.

The resulting lithographic printing plate that does not require dampening water has recesses with a depth of 7μ or more serving as image areas, and when this plate is used to print with a normal offset printing machine, printed matter with a sufficient ink film thickness is obtained. was gotten.

Example 2 Naphthoquinone-1,2-diazido-5-sulfonic acid ester of phenol novolak resin was applied to a chemically treated aluminum plate manufactured by Sumitomo Light Metal Co., Ltd. to a thickness of 2.7 μm.
It was painted so that Next, a silicone rubber layer having the following composition was provided thereon to a thickness of 2 μm.

(1) Dimethylpolysiloxane (molecular weight approximately 30,000,
Terminal hydroxyl group) 100 parts (2) Ethyltriacetoxysilane 5 parts (3) γ-aminopropyltriethoxysilane 3 parts The resulting lithographic printing original plate that does not require dampening water is subjected to image exposure and developed with ethanol, requiring no dampening water. A lithographic printing plate was obtained. This was subjected to the same post-treatment as in Example 1 to obtain a lithographic printing plate that did not require dampening water and had deep recesses as image areas.

When this printing plate was used for direct printing on a Douwitson Dualis Model 700 printing machine,
A printed matter with sufficient ink film thickness was obtained.

Claims (1)

[Claims] 1. In a lithographic printing plate that does not require dampening water and has a silicone rubber layer lined on a substrate as a non-image area, after providing a non-adhesive material layer on the printing plate, the non-adhesive substance layer on the image area is A method for post-processing a lithographic printing plate that does not require dampening water and is characterized by removing only a material layer.