JPS6154224B2 - - 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 printed lines and non-printed lines on the same plane in appearance, but this printing method is carried out in the following process. be exposed. That is, first of all, water and fat repel each other, so the non-image areas are made hydrophilic by chemical or mechanical treatment, and the image areas are made hydrophilic by transfer of fatty resin or The printing plate is made lipophilic by photographic printing or the like, and then water is transferred to this printing plate so that the water adheres only to the hydrophilic non-image areas, and then ink is further transferred to this printing plate. In this way, this ink does not adhere to the non-print areas where water is present, but only to the lipophilic print areas, and is then transferred to the printing substrate to achieve the desired effect. This is done through the process of obtaining printed matter.

However, with 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 may cause soiling, and also cause the dampening water to be covered. Transfer to printed matter also causes a change in the dimensions of the printed material, which has a major drawback, especially in multicolor printing, in that the printed image becomes unclear. 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 the 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 disadvantages, 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 thereon and exposed, and the exposed areas are exposed to light. A method of obtaining a lithographic printing plate by developing the layer using photolysis and then peeling off the silicone rubber layer in the exposed area (Special 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. Moreover, there is a serious drawback that the adhesion between the silicone and the photosensitive layer is not sufficient, and the silicone is easily lost during development and printing. Since the process is performed after exposure and development, there is a disadvantage that the operation is complicated.

Furthermore, this method requires equipment unique to this method for plate making, and also requires advanced plate making technology.

As an improvement on the above points, there is a method of dry lithography using a lithographic plate made from a conventional PS plate (see Japanese Patent Publication No. 44-23042 and Japanese Patent Publication No. 47-32906).
However, since this method uses a solution or emulsion coating method to form a silicone coating, it actually requires a new coater, and also requires a catalyst in the silicone solution. If a one-component silicone without a catalyst is used, gelation will progress over time, making it necessary to add a catalyst just before coating. Although it is more stable than the two-component type, it has manufacturing disadvantages such as a longer plate-making cycle because it takes a long time for the silicone to harden.

In addition, with this method, after applying the two-component or one-component type silicone, until it is sufficiently cured, the surface of the uncured silicone is soft and sticky, so it is easy for dust to adhere to it. After the silicone hardens, the unevenness formed by the dirt residue becomes ink receptive, which has the serious disadvantage of causing background smudges and pinholes.

In order to solve these drawbacks, the present inventors have conducted intensive research on printing plates for lithographic printing, and have found that they are stable over time, can easily form a silicone layer, and that they can design and select the silicone to be used. We have completed an invention related to an easy method for manufacturing printing plates for lithographic printing.

That is, in the present invention, a solvent-soluble or swellable image is formed on a substrate whose surface is at least ink receptive, and then an uncured image that has been previously coated on a support is applied to the surface containing the image. After pressing the surface of a curable silicone resin layer other than a photocurable type, the silicone is cured, and then the support is peeled off to form a cured silicone layer on the substrate, and the image line is dissolved or removed with a solvent. After swelling, the image line and the silicone layer on the image line are removed to form an image area consisting of the exposed surface of the substrate and a non-image area consisting of the cured silicone layer on the substrate, and the above method. The method is characterized in that a curing agent is allowed to adhere to and penetrate into the uncured silicone layer immediately before compression bonding.

The present invention will be explained in detail below.

First, the structure of the present invention will be explained based on the drawings. As shown in FIG. 1, a solvent-soluble or swellable object line 2 is formed on one surface of a substrate 1. The method for forming these lines may be any method of patterning a substance that is soluble or swellable in a solvent; for example, printing a PS plate, wipe-on plate, or photoresist using a predetermined method to form the lines. Alternatively, any method such as drawing characters or other images using a marking pen or the like may be used.

The material of the substrate 1 may be any material as long as it is solvent-resistant and has at least a lipophilic surface to which ink can easily adhere, such as metals such as aluminum, iron, copper, zinc, and stainless steel, or laminates thereof; Plastic films such as polyester and polypropylene are preferred. These should not only be resistant to solvents but also have excellent dimensional stability with little elongation and surface smoothness required for printing substrates.

Next, as shown in FIG. 2, the surface of the uncured silicone layer 4 previously coated on the support 3 is pressure-bonded (laminated) onto the surface on which the image line has been formed as described above. This pressure bonding requires laminating with sufficient pressure so that the uncured silicone layer completely adheres to all the non-image areas of the substrate 1 without containing any air bubbles. You can also use a method of laminating the surface of the uncured silicone layer to the surface on which the image area is formed and pressing it with a roll from above, but a more efficient method is to use a laminating roll or a calendar roll. It is advantageous to use

Before applying the silicone resin to the support 3,
If a curing agent is required, it can be added in advance, or it can be coated on the support 3 without adding a curing agent, dried, and the curing agent can adhere to and penetrate into the silicone layer before pressing. You can choose either one. To adhere and penetrate the hardening agent into the silicone layer, any method may be used as long as the hardening agent penetrates into the silicone, but to do this effectively, apply the hardening agent as it is or dilute it with an appropriate solvent and apply it to the silicone surface. The advantage of this method is that the catalyst penetrates from the substrate side of the silicone layer.
This improves the adhesion between the cured silicone layer and the substrate.

The silicone resin used in the present invention is preferably one having low oil repellency or ink adhesion after curing, and a thermosetting type other than a photocuring type, a room temperature curing type, etc. are used. For example, dimethyl silicone raw rubber, methylphenyl silicone raw rubber,
Heat-vulcanized silicone rubber such as methylphenyl vinyl silicone raw rubber; SiOH, SiOR,
A two-component cold-curable silicone rubber that becomes a rubber elastic material by crosslinking siloxanes with reactive groups such as SiH, SiCH=CH ₂ with a catalyst; a condensation-curing type silicone rubber that reacts with moisture in the air. Silicone rubber that cures and is generally known as one-component room-temperature vulcanizable silicone rubber; silicone varnish, etc. can be used.

Heat-curable silicone rubber can also be vulcanized by radiation, but organic peroxides, fatty acid azo compounds, sulfur, etc. are used as curing agents, and the most common method is a two-component method using organic peroxides. As a curing agent of the room temperature vulcanization type, a condensation catalyst of an acidic or basic substance such as an organometallic acid salt, an organic amine, a quaternary ammonium, or a phosphonium compound is used for a type that heats and cures at room temperature by a condensation reaction. Types that cure by vulcanization through addition polymerization between unsaturated groups and SiH use a catalyst such as palladium or platinum as a curing agent. Also,
One-component cold-curable silicone rubber and silicone varnish can be cured without a curing agent.

To form the silicone layer 4 on the support 3, silicone is mixed with an appropriate solvent as necessary to adjust the viscosity to be easy to coat, and this is applied by brushing.
The silicone layer may be coated on the support 4 by a method such as spin coating, rod coating, or roll coating and the solvent may be evaporated, and the thickness of the silicone layer at this time may be approximately 2 to 30 μm.

Solvents used for the above purpose include ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, aromatic hydrocarbon solvents such as benzene, toluene, and xylene, halogen hydrocarbon solvents such as trichlorethylene and tetrachloroethylene, and isopropanol. , alcoholic solvents such as octanol, and the like.

The material of the support 3 may be selected in consideration of the curing temperature and reaction mechanism of the silicone resin used.
The support surface must also be smooth so that the silicone surface is smooth after curing. Furthermore, after the silicone is cured, it is required that it be easily peeled off from the support 3, such as films made of polyolefins such as polyethylene and polypropylene, cellulose acetate, cellulose triacetate, polyvinyl alcohol, polymethacrylate, polyamide, etc. Polystyrene, polyvinyl chloride, polyvinyl chloride vinyl acetate, polyvinylidene chloride vinyl chloride, polyethylene terephthalate, polyvinylidene chloride, polyethylene fluoride,
Films or sheets made of acrylic resin, polycarbonate, etc. are used, and metal foils, laminates thereof, metal plates, etc. may also be used after being subjected to a peeling treatment with a surfactant or the like.

When the pressure bonding is completed as shown in FIG. 2, the uncured silicone adheres closely to the image line 2 and the non-image area, that is, the surface of the substrate 1. Next, the silicone is cured by treatment such as heating or by being left at room temperature. The silicone becomes fixed to the substrate 1 at the same time as it cures. In order to make this adhesion stronger, it is preferable that the surface of the substrate 1 is treated with a primer. In this case, the primers include vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, N-
Examples include (trimethoxysilylpropyl)ethylenediamine, 3-aminopropyltriethoxysilane, etc. alone or mixtures thereof, as well as partial hydrolysates or cohydrolysates thereof, and these can be coated by spin coating, rod coating, etc. Application may be carried out by conventional methods such as coating, brushing, spraying, etc.

After curing the silicone in this way,
As shown in FIG. 3, the support 3 is peeled off from the substrate 1. At this time, the cured silicone layer is firmly adhered to the substrate 1, and the peeling transfers the cured silicone layer to the substrate 1 side. Next, a solvent is poured onto the silicone surface to dissolve or swell the image through the silicone, and then the image and the silicone on the image are removed. FIG. 4 shows a state in which the silicone on the image line 2' bulges due to dissolution or swelling of the image line 2'. In this state, the silicone can be easily removed with a soft cloth, paper, sponge, rubber, etc. The solvent used here may be any solvent as long as it dissolves or swells the image, and ketone solvents such as methyl ethyl ketone (MEK) and acetone, aromatic solvents such as toluene and xylene, or mixed solvents thereof are used.

FIG. 5 shows a lithographic printing plate obtained by the above method, and the exposed portion of the substrate becomes the image area.

FIG. 6 shows how the ink 5 is applied to the image area.

As is clear from the above description, in the present invention, a silicone layer coated on a support in advance is laminated with a substrate, cured, and transferred. Not only does it eliminate the need to manage cleaning solutions and waste solvents, but the coating surface is protected by a support during the curing reaction of the silicone coating, which prevents dust from sticking and provides a good coating surface. It has the excellent advantage of being able to

Furthermore, in the method in which a hardening agent is applied and permeated immediately before pressure bonding, the silicone layer before pressure bonding does not contain a hardening agent, so it is possible to form a silicone layer that is stable over time, and at the same time, it is possible to form a silicone layer that is stable over time. It also has the great advantage of being able to store silicone.

Next, examples of the present invention will be given.

Example 1 A condensation type silicone rubber KS705F for release paper manufactured by Shin-Etsu Chemical Co., Ltd. was coated on a polypropylene film having a thickness of 12 μm without adding a catalyst so that the dry coating film was 15 μm. On the other hand, a presensitized plate has a positive type diazo photosensitive layer on an aluminum plate.
Print DP-100 (trade name manufactured by Tokyo Ohka Kogyo),
Stretch lines were formed, and KBP41 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied as a primer so that the dry coating film had a thickness of about 0.5 μm.

Next, a catalyst diluted 5 times with MEK is sprayed onto the coated surface of the polypropylene film provided with the above coating film, so that the catalyst adheres and penetrates into the silicone layer, and the coated surface is applied to the surface of the aluminum plate having the image lines. I pressure laminated it so that it would fit. After heating the pressure laminated product to 100℃ to harden the silicone, the aluminum plate and polypropylene film were peeled off, and the cured silicone rubber transferred onto the aluminum plate, causing it to adhere to the aluminum plate. Ta.

Next, the surface of this aluminum plate was sufficiently soaked in MEK to dissolve the image, and then the silicone layer on the image was removed by lightly rubbing the silicone surface with a soft cloth.

When this aluminum plate was used as a lithographic printing plate on a KOR printing machine and printed without supplying dampening water, 10,000 clear prints were obtained.

Example 2 Printing was carried out in the same manner as in Example 1 except that the additive type silicone rubber KS774 manufactured by Shin-Etsu Chemical Co., Ltd. was used, and the results were almost the same as in Example 1.

Example 3 KE77 (trade name manufactured by Shin-Etsu Chemical, silicone rubber)
100 parts by weight KF99 (〃, silicone oil)
10 parts by weight PL-3 (Catalyst) 0.5 parts by weight The above composition was applied onto a polypropylene film so that the dry film thickness was 15 μm. This thing is
It did not harden even after being left at 25°C for one day.

On the other hand, a presensitized plate DP-100 (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) having a positive type diazo photosensitive layer was printed on an aluminum plate to form an image, and γ-chrysidoxypropyl trifluoride was used as a primer. methoxysilane
50 parts by weight of titanium titanium trabutoxide was applied so that the dry coating film had a thickness of approximately 0.5 μm, and a polypropylene film with the above coating film on this surface was laminated under pressure so that the coating surfaces matched. . 150 pieces of pressure laminated material like this
When heated to ℃, the silicone was cured after 30 minutes. Next, when the aluminum plate and polypropylene film were peeled off, the cured silicone rubber had transferred onto the aluminum plate and adhered to the aluminum plate.

Next, the surface of this aluminum plate was sufficiently soaked in MEK to dissolve the image lines, and then the silicone layer on the image lines was removed by lightly rubbing the silicone surface with a soft cloth.

When this aluminum plate was used as a lithographic printing plate on a KOR printing machine and printed without supplying dampening water, 10,000 clear prints were obtained.

[Brief explanation of the drawing]

1 to 4 are schematic cross-sectional views for explaining the process of manufacturing a lithographic printing plate by the method of the present invention, and FIG. 5 is a lithographic printing plate obtained by this method. FIG. 6 is a schematic cross-sectional view of the printing plate, and FIG. 6 is a schematic cross-sectional view of the main printing plate with ink attached to the image area. DESCRIPTION OF SYMBOLS 1...Substrate, 2...A streak made of a solvent-soluble or solvent-swellable substance, 3...Support, 4...
Uncured curable silicone layer, 4... Cured silicone layer, 2'... Image dissolved or swollen by solvent, 5... Ink.

Claims (1)

[Claims] 1. Forming a solvent-soluble or swellable streak on a substrate whose surface is at least ink receptive;
Next, the surface of an uncured non-photocurable silicone resin layer coated on the support in advance is pressed onto the surface containing the image, and the silicone layer is cured, and then the support is peeled off. Further, by dissolving or swelling the image with a solvent and removing the image and the silicone layer on the image, an image area consisting of the exposed surface of the substrate and a non-containing silicone layer consisting of the cured silicone layer are formed on the substrate. 1. A method for producing a lithographic printing plate, the method comprising forming an image area. 2. The method according to claim 1, wherein a curing agent is allowed to adhere to and penetrate into the uncured silicone layer immediately before compression bonding.