JPS6154221B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a lithographic printing plate that does not require dampening water.

In lithographic printing, a plate is used that does not have clear heights on the plate surface like letterpress or intaglio printing, and has a printed area and a non-printed area on the same plane in appearance.This printing method involves the following process. It will be held in In other words, first of all, water and fat repel each other,
The non-image area is made hydrophilic by chemical or mechanical treatment, and the image area is made lipophilic by transfer of a fatty resin or photographic printing, and then water is transferred to the printing plate. After that, water is applied only to the hydrophilic non-image areas, and then ink is further transferred to this plate surface. In this way,
This ink does not adhere to the non-print areas where water is present, but only to the lipophilic print areas, so
This is then transferred to a substrate to obtain the desired printed matter.

However, in this lithographic printing method, for example, the transfer of the dampening water to the ink roller causes the ink to emulsify on the ink roller, which causes stains, and also The transfer to the printing material also causes a change in the dimensions of the printing material, so there is a major drawback that the printed image becomes unclear, especially in multicolor printing. In addition, in this lithographic printing method, in order to obtain printed matter with a constant color tone, it is necessary to maintain a constant balance between the amount of dampening water and the amount of ink. It is very difficult to maintain this balance, which has the disadvantage of causing variations in color tone of printed matter.

For this reason, attempts have been made to develop lithographic printing plates that do not require dampening water in order to improve the above-mentioned drawbacks, but none of the plates known to date are still sufficiently satisfactory for practical use. It has not yet been possible to demonstrate its properties.

For example, a diazo photosensitive layer made of a diazo type photosensitive composition and a dimethylpolysiloxane rubber layer are formed on a substrate such as an aluminum plate, and then a positive film is further laminated thereon and then exposed. A method of insolubilizing the diazo photosensitive layer in the exposed areas, removing the diazo photosensitive layer in the non-exposed areas by development treatment, and then peeling off the dimethylpolysiloxane rubber layer in the non-exposed areas (Tokuko Sho)
44-23042), or on a substrate such as an aluminum plate, a diazo photosensitive layer, an adhesive layer, and a silicone rubber layer are sequentially formed, and then a negative film is superimposed on this layer and exposed. A method of obtaining a lithographic printing plate by developing the photosensitive layer using photodecomposition and then peeling off the silicone rubber layer in the exposed area (Japanese Patent Publication No. 1973-
16044) is known.

However, in all of these methods, a non-photosensitive silicone rubber exists between the diazo photosensitive layer and the positive or negative film, so it is difficult to accurately reproduce the pattern appearing on the positive or negative film. Furthermore, since the silicone rubber layer is peeled off by utilizing changes in the solvent solubility of the photosensitive layer, the edges of the image formed on the silicone rubber layer after peeling off are poor.
It has a serious drawback of not being sharp. Furthermore, in these cases, the configuration of the edition is 2~
It is a multilayer consisting of three layers, and since the exposed substrate becomes the printing area, the printing depth is large, and during printing, the ink transfer from the ink roll to the plate, and from the plate to the blanket or printing medium is poor. There is a disadvantage that it is unfavorable in terms of printability.

On the other hand, it is also possible to form a patterned protective layer on a substrate in advance, coat the entire surface of the substrate and the protective layer with silicone, and then supply a liquid (such as a solvent) that can dissolve the protective layer to dissolve the protective layer. A method of dissolving the silicone and simultaneously removing the silicone on the protective layer is known (see Japanese Patent Publication No. 44-23042).
According to this method, a printing plate with a single layer of silicone can be obtained instead of the multi-layered one described above, so it has the advantage of a small printing depth, but on the other hand, it requires coating with silicone during the printing plate process, making the operation complicated. It has the disadvantage of being sloppy.

As a method to improve these drawbacks and disadvantages, there is a method of modifying the surface of silicone to make it lipophilic and making it into a lithographic printing plate, for example, a method of destroying the surface of the silicone layer with an electron beam, laser beam, electrical discharge, etc. (see Japanese Patent Publication No. 42-21879), or a method of making the silicone layer lipophilic by scanning it with glow or a corona beam (Japanese Patent Publication No. 48-218).
8207) is known.

According to these methods, silicone is a single layer;
Although the printing plate process has the advantage of not being particularly complicated, the former method requires high energy to destroy the surface of the silicone layer, requiring a large-scale plate-making device, and the latter scanning method requires high energy to destroy the surface of the silicone layer. The disadvantages are that the printing plate time is long and special equipment is required.

The present inventors completed the present invention as a result of intensive research in order to solve the conventional disadvantages and drawbacks,
This involves sequentially forming a silicone layer and a patterned protective layer on the silicone layer on the surface of the substrate, and then treating with a silicone etchant to remove the silicone layer in the non-protective layer area, and then removing the protective layer. The present invention relates to a method for producing a lithographic printing plate, characterized in that an image area consisting of the exposed surface of the substrate and a non-image area consisting of a silicone layer are formed on the substrate, and according to this method, A lithographic printing plate can be obtained that can perform surface exposure treatment with a short operation time, and can be printed in an exposure and development process that does not require vacuum treatment or special equipment, and has excellent resolution and printability.

The silicone etchant used in the method of the present invention is capable of removing the silicone layer of the target area in a relatively short period of time, and is preferably one that does not erode the protective layer as much as possible. One or more mixtures of sulfuric acid, ferric chloride, phosphoric acid, chromic acid, nitric acid, etc., mixtures of at least one of these with copper sulfate or silver nitrate, alkaline substances such as sodium hydroxide, etc. Illustrated.

The advantages of the method of the present invention using such a silicone etching agent will be described in detail as follows.

(1) In the process using a silicone etchant in the method of the present invention, the silicone layer removed by this process is extremely thin and the process time is short, so so-called side etching hardly occurs, and therefore the resolution is low. Since the resolution of the protective layer (resist) is almost reproduced, a printing plate with high resolution can be obtained.

(2) Furthermore, the treatment with silicone etchant can be carried out by dipping treatment, spraying treatment, steam contact treatment of silicone etchant, etc., and does not require any special equipment.

(3) The lithographic printing plate of the present invention is made of a single layer of silicone, which is usually formed with an extremely thin film, so there is almost no difference in height between the printed area and the non-printed area, and the ink plate and blanket are easily formed. As a result, image reproducibility and ink color development are improved, resulting in high-quality printed matter.

(4) Since the silicone used to form the silicone layer does not require pattern-forming ability, it can be freely selected from organopolysiloxanes that have excellent solvent resistance, abrasion resistance, and adhesion to the substrate.

(5) Negative or positive plates can be easily created by selecting the pattern of the protective layer (resist layer).

Hereinafter, the present invention will be explained in detail based on the drawings.

First, the schematic partial cross-sectional structure of the lithographic printing plate according to the present invention is as shown in FIG. The ink adheres to the image areas 3. Figure 1~
FIG. 3 schematically shows the process of manufacturing this lithographic printing plate, in which a silicone layer 2 is provided on one side of the substrate 1 as shown in FIG. A patterned protective layer 4 is provided on the silicone layer 2.

Next, when this entire surface is treated with a silicone etchant, the silicone layer in the area where the protective layer 4 is not provided is removed and the substrate is exposed, as shown in FIG. is formed. When the protective layer 4 is then removed, a lithographic printing plate according to the present invention as shown in FIG. 4 is obtained.

It is desirable to use a material that is not attacked by silicone etching agents as the substrate 1, and examples thereof include metal plates such as copper plates, aluminum plates, stainless steel plates, zinc plates, iron plates, or nickel-plated copper plates or iron plates, and the above-mentioned metal plates. Examples include plates lined with resin or plastic film coating or lamination, various plastics such as polyester and polypropylene, and substrates such as paper and plastic coated with aluminum or other metal foil.

It is desirable that the silicone layer provided on the surface of the substrate 1 be formed as uniformly as possible while maintaining strong adhesion. For this purpose, the surface of the substrate 1 should be cleaned in advance by an appropriate method, and if necessary, It is desirable to take measures such as roughening the surface. It is also possible to apply a primer to the surface of the substrate 1 in advance to improve adhesion (adhesion).
Silanes such as methoxyethoxy)silane, 3-glycidoxypropylmethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, mixtures thereof, or partial (co)hydrolyzed condensates thereof etc. are used.

The thickness of the silicone layer is preferably as thin as possible within the range that provides sufficient printing durability, and is usually 1 to 20 μm thick.
The thickness may be about m. If the thickness is too large, this removal operation using a silicone etchant becomes difficult and disadvantageous, so the thickness is more preferably about 1 to 5 μm.

The specific type of silicone used to form this silicone layer 2 is one that cross-links and cures at room temperature or by heating after coating to become an ink-repellent silicone rubber elastic body, which contains all organic groups bonded to silicon atoms. It is best to use a highly polymerized organopolysiloxane (which has excellent ink repellency) as its main component, with 90 mol% or more of methyl groups.
These include (1) a highly polymerized diorganopolysiloxane in which both ends of the molecular chain are capped with hydroxyl groups and 90 mol% or more of the organic groups are methyl groups; methylhydrodiene polysiloxane or ethyl polysilicate as a crosslinking agent; A condensation catalyst consisting of an organic acid metal salt, (2) a vinyl group-containing highly polymerized diorganopolysiloxane (at least 90 mol% of organic groups other than vinyl groups are methyl groups), and a methylhydrodiene polysiloxane as a crosslinking agent. , and a platinum-based catalyst as an addition reaction catalyst, (3) a highly polymerized diorganopolysiloxane in which both ends of the molecular chain are blocked with hydroxyl groups and 90 mol% or more of the organic groups are methyl groups, and a crosslinking agent. Examples include silanes or low polymerization degree siloxane compounds having three or more hydrolyzable groups such as acetoxy groups, amino groups, oxime groups, or propenoxy groups in one molecule. In the present invention, the types exemplified in (1) or (2) above are particularly preferred.

In addition, organic groups other than methyl groups in the above generally include aryl groups such as phenyl groups, alkenyl groups such as vinyl groups, alkyl groups such as ethyl groups and propyl groups, and halogen-substituted alkyl groups such as trifluoropropyl groups. is exemplified.

In the compositions exemplified in (1), (2) and (3) above, if necessary, ordinary diorganopolysiloxanes such as dimethylpolysiloxane may be added to improve the properties of the cured coating film in order to further improve the ink repellency. It is permissible to add a small amount of reinforcing filler, such as fine silica powder, to the extent that it does not cause any adverse effects, and for the purpose of improving printing durability.

For the purposes of the present invention, the protective layer 4 provided on the silicone layer 2 is made of a material that is stable to silicone etching agents and can be easily patterned. During the process (this process is completed in a relatively short time), it is sufficient that the layer functions as a protective layer for the non-image area, and it does not necessarily need to be highly corrosion resistant. things are available.

Examples of such materials include photoresists containing photosensitive groups such as diazidoquinone, azide, diazo, cinnamic acid, and dichromic acid, as well as numerous photosensitive resins and coatable photosensitive materials.

To form this patterned protective layer 4
(a) A method of patterning using a commercially available photoresist using an ordinary plate making method, (b) A method of forming a resist layer into a pattern by screen printing using an ink containing an acid-resistant or alkali-resistant resin, ( c) Film-forming properties Any method may be used, such as hand-painting the resin liquid or transferring it using an appropriate printing means.

Specific treatment methods for removing silicone from the non-protective layer using a silicone etching agent include dipping, coating, spraying, etc. According to this method, the desired treatment can be completed simply by bringing the surface to be treated and the vapor into face-to-face contact, so in this case, the substrate may be lined with, for example, resin. The advantage is that uncoated metal sheets can be used.

As mentioned above, the thickness of the silicone layer 2 is 1 to 1.
Since it is a thin film of about 20 μm, the silicone in the non-protective layer is easily removed by the treatment with the silicone etchant, and the image area (ink receiving area) 3
is formed.

Next, in order to remove the protective layer 4, if a commercially available photoresist is used, it may be dissolved or peeled off using an appropriate solvent. It can be easily peeled off or dissolved by using ethyl cellosolve, etc. for Tokyo Ohka TPR, and toluene, etc. for screen printing resist layers. Strong acids and strong alkalis should be avoided as they will attack the silicone layer. In addition, silicone generally has surface characteristics that make it weakly bonded to other substances, so
The protective layer 4 can also be removed using a suitable adhesive tape.

By removing the protective layer 4 in this manner, a non-image area (ink repelling area) 2' is formed in which the resolution of the resist is reproduced almost as is.

The above-mentioned (1) is achieved by the manufacturing method of the present invention described above.
This lithographic printing plate does not require dampening water, so it can be printed directly onto the printing material without using a blanket. It is possible to print by attaching it to a letterpress printing machine, which has the advantage of avoiding the work required to smooth out uneven printing pressure as in conventional letterpress printing, and producing printed matter with excellent resolution. Given.

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

Example 1 Dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., KS-705F) was applied to a degreased and cleaned aluminum plate whose back surface was coated with epoxy resin so that the film thickness after drying and curing was 5 μm. A silicone layer was formed by drying and curing, and on top of this a photoresist solution (AZ-111, manufactured by Shippray) containing 1% by weight of a surfactant (FC-431, manufactured by 3M) was applied to form a silicone layer with a film thickness of 3 μm after drying. It was applied using a spin coating method and dried.

Next, a resist image (protective layer) is formed on the silicone layer by exposing and developing the negative original plate, and then placing it in 7% hydrochloric acid at room temperature.
The non-protective silicone layer was removed by immersion treatment for 10 minutes, washed with water and dried, and then the protective layer was removed with acetone to obtain a lithographic printing plate.

This printing plate showed a printing durability of 50,000 sheets.

Example 2 After forming a silicone layer and a resist image on an aluminum plate in the same manner as in the previous example (however, the aluminum plate was not coated with a resin or the like on the back side), it was treated with hydrogen chloride generated from 35% hydrochloric acid. The non-protective silicone layer was removed by steam treatment at room temperature for 3 minutes, washed with water and dried,
The protective layer was then removed with acetone to obtain a lithographic printing plate.

This printing plate showed a printing durability of over 50,000 sheets.

Example 3 Dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., KS-774) was applied to a copper plate with a polyester film laminated on the back side so that the film thickness after drying and curing was 5 μm, and the film was dried and cured to form a silicone layer. Then apply a photoresist solution (manufactured by Tokyo Ohka Co., Ltd.) on top of this.
TPR) was applied by spin coating to a dry film thickness of 3 μm and dried.

Next, a resist image (protective layer) is formed on the silicone layer by exposing and developing the positive master plate.
After forming this, it was immersed in a 5% ferric chloride aqueous solution at room temperature for 5 minutes to remove the silicone layer on the non-protective layer, washed with water and dried, and then the protective layer was peeled off with ethyl cellosolve acetate. A printing plate for lithographic printing was obtained.

This printing plate showed a printing durability of 30,000 sheets.

Example 4 Dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., KE-45RTV) was placed on an aluminum plate similar to Example 1.
was applied so that the film thickness after drying and curing was 3 μm, drying and curing to form a silicone layer, and on top of this a photoresist solution similar to that used in Example 1 was applied and after drying, it was patterned by photolithography. I went there. Next, the silicone layer on the non-protective layer was removed by spraying 5% nitric acid at room temperature for 3 minutes, washed with water and dried, and the protective layer was removed with acetone to form a lithographic printing plate. Obtained.

This printing plate showed good printing durability of 50,000 sheets or more.

Example 5 After forming a silicone layer and a resist image thereon in the same manner as in Example 1 on an aluminum plate similar to Example 1, this was immersed in 5% hydrochloric acid at 25°C for 5 minutes to form a non-protective layer. The silicone layer was removed from the area, washed with water and dried. The protective layer was then peeled off using adhesive tape (manufactured by Nitto Denko Corporation, paper adhesive tape) to obtain a printing plate for lithographic printing.

When this printing plate was printed directly onto a printing material without using a blanket, 30,000 good prints were obtained.

Example 6 The film thickness after drying and curing of dimethylpolysiloxane (KS-705F) was 5 μm on the same copper plate as in Example 2.
The silicone layer was formed by drying and curing. Next, on this silicone layer, printing was performed using a silk screen plate prepared in advance using a screen ink consisting of 20 parts by weight of screen oil mainly composed of ethyl cellulose and pine oil and 80 parts by weight of glass frit. This was immersed in 3% hydrochloric acid at 25° C. for 5 minutes to remove the silicone layer other than the screen ink resist portion, washed with water and dried, and then the screen ink resist layer was peeled off to obtain a lithographic printing plate.

When this printing plate was printed directly onto a printing material without using a blanket, 30,000 good prints were obtained.

Example 7 Dimethylpolysiloxane (KS-774) was applied on aluminum foil to a polyester film with a thickness of 0.1 mm so that the film thickness after drying and curing was 5 μm, and the silicone layer was formed by drying and curing. A photoresist solution (manufactured by Fuji Yakuhin, FSR FC-431 with 2% addition) was applied on top by a spin coating method and dried so that the film thickness after drying was 3 μm.

Next, a positive master plate was attached and patterned using photolithography. Next, this material was treated in 5% sodium hydroxide at room temperature for 5 minutes to gradually remove the silicone layer on the non-protective layer, washed with water and dried, the photoresist layer was peeled off, and a lithographic printing plate was prepared. Obtained.

This printing plate showed a printing durability of 10,000 sheets.

[Brief explanation of the drawing]

FIGS. 1 to 4 show schematic partial cross-sectional structures of each step of manufacturing a lithographic printing plate by the method of the present invention. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Silicone layer, 3...An image area consisting of the exposed surface of the substrate, 4...A patterned protective layer, 2'...A silicone layer constituting a non-image area.

Claims (1)

[Claims] 1. Sequentially forming a silicone layer and a patterned protective layer on the silicone layer on the surface of the substrate, then treating with a silicone etchant to remove the silicone layer in the non-protective layer portion, and then removing the protective layer. A method for producing a lithographic printing plate, comprising forming on a substrate an image area consisting of the exposed surface of the substrate and a non-image area consisting of a silicone layer.