JPS6154225B2 - - 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, 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 material.

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, it is necessary to maintain a constant balance between the amount of dampening water and the amount of ink in order to obtain printed matter with a constant color tone. It is very difficult to maintain the same color, and this 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 on this layer and then exposed to light. 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, there is a serious drawback that the adhesion between the silicone layer and the photosensitive layer is insufficient, and the silicone is easily lost during development and printing.

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).
is known, but since this method employs coating using a solution or emulsion as a method of forming a silicone coating film, it actually requires a new coater, and it also requires a catalyst in the silicone solution. If a one-component silicone that does not use 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.

On the other hand, a method is known in which a dry lithographic printing plate is obtained by forming a photosensitive silicone layer on a substrate and then contact-printing a transparent original thereon (see Japanese Patent Publication No. 52-38763). repellency,
It is difficult to design the photosensitive silicone itself because it is necessary to simultaneously satisfy the conditions of resolution and printing durability.

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

That is, the present invention forms a solvent-resistant image on a substrate and a solvent-soluble or swellable protective layer on the image, and then coats the surface containing the protective layer on a support in advance. After pressing the surface of an uncured curable silicone resin layer other than a photocurable type, the silicone layer is cured, the support is peeled off, and the protective layer is dissolved or swollen with a solvent, and then the protective layer is cured. By removing the silicone layer on the layer and the protective layer, a solvent-resistant image area and a non-image area consisting of a cured silicone layer are formed on the substrate, and in the above method, the curing agent is not applied immediately before crimping. It is characterized by adhesion and penetration into the cured silicone resin layer.

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. form. As a method for forming such lines, any method may be used as long as it is a method of patterning a multilayer material of a solvent-resistant material and a solvent-soluble or swellable material.
A PS plate, wipe-on plate, or photoresist is printed using a predetermined method, and then burned as is or further burnt to form a solvent-resistant image.The solvent-resistant image is then corona-charged to form a solvent-soluble or swellable resin. The protective layer may be formed by electrostatically adhering the powder and fixing it by heat, or it may be formed by lacquering with emulsion ink or inking using dampening water.

Furthermore, as shown in FIG. 1b, a pattern is formed on a metal substrate 1 using a photoresist that is soluble or swellable in a solvent, this is used as a protective layer 3, and then etched to form a pattern on the metal substrate 1. A part of the print line 2' may be made solvent-resistant.

The material of the substrate 1 only needs to be solvent-resistant.
For example, metals such as aluminum, iron, copper, zinc, and stainless steel, or laminates thereof, and plastic films such as polyester and polypropylene are preferred. These should not only be resistant to solvents but also have excellent dimensional stability and smoothness with little elongation, which are required for printing substrates.

Next, as shown in FIG. 2, the surface of the uncured silicone layer 4 previously coated on the support 5 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 5,
If a curing agent is required, it can be added in advance, or it can be applied onto the support 5 without adding a curing agent, dried, and the curing agent can be allowed to adhere 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 can 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 layer. 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 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-curable silicone rubber such as methylphenyl vinyl silicone raw rubber; SiOH, SiOR,
A two-component cold-curable silicone that becomes a rubber elastic body by crosslinking siloxanes with reactive groups such as SiH and SiCT=OH ₂ with a catalyst; a condensation curing type that cures by reacting with moisture in the air. Silicone rubber that is commonly 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 adhesives, and the most common method is to use organic peroxides.

As a reinforcing agent for a two-component room temperature vulcanization type, a condensation catalyst of an acidic or basic substance such as an organic metal salt, an organic amine, a quaternary ammonium, or a phosphonium compound is used for a type that heats and cures at room temperature through a condensation reaction. do. 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 5, 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 onto the support 5 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 5 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 5, 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 5 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, and the protective layer on the image is dissolved or swollen by the solvent through the silicone, and then the protective layer and the silicone on the protective layer are removed. FIG. 4 shows a state where the silicone on the image line is raised due to dissolution or swelling of the protective layer 3'. 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 protective layer, and ketone-based 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 ink 6 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 rubber adhesion 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.

Furthermore, it has the excellent advantage of being able to easily create planographic printing plates that do not require dampening water even from solvent-resistant images such as negative type PS plates, so this printing plate can be used in letterpress printing departments that mainly use negative manuscripts. This made it easier to perform direct printing.

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 SGN (product name manufactured by Fuji Photo Film Industries) having a negative type diazo photosensitive layer on an aluminum plate is printed to form a solvent-resistant image, and this image is charged by corona discharge. ,
Solvent-soluble resin powder was electrostatically adhered and further heat-fixed to form a protective layer.

Further, KBP41 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) as a primer was applied and dried so that the dry coating film was 0.5 μm.

Next, a catalyst (Cat, PS, manufactured by Shin-Etsu Chemical Co., Ltd.) diluted five times with MEK is sprayed onto the coating surface of the polypropylene film provided with the above coating film to adhere and impregnate the silicone layer with the catalyst. The coating was laminated under pressure so that the surface of the coating was aligned with the surface of the substrate. After heating the pressure laminated product to 100℃ to cure the silicone, the aluminum plate and polypropylene film were peeled off, and the cured silicone rubber was transferred onto the aluminum plate and adhered to the aluminum plate. .

Next, the surface of this aluminum plate was sufficiently soaked with MEK to dissolve the protective layer, and then the silicone surface was lightly rubbed with a soft cloth to remove the protective layer and silicone layer on the image lines. When this aluminum plate was used as a lithographic printing plate and printed using an AB Dick printing machine without supplying dampening water, 10,000 clear prints were obtained.

Example 2 Release paper added type silicone rubber KS774 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, the surface is cleaned in the usual way and has a thickness of 0.5 mm.
A positive type photoresist AZ-111 (manufactured by Shippray Co., USA) was applied to the surface of the resin-backed zinc plate to a dry film thickness of 1 .mu.m, and after drying, a transparent positive original was attached, exposed, and developed to form a protective layer. Then specific gravity
The zinc plate was soaked for 4 minutes in diluted nitric acid (1.38% nitric acid diluted 10 times with water) and etched by about 20 μm to form an image area under the protective layer.

After washing and drying this zinc plate, γ-glycidoxypropyltrimethoxysilane was used as a primer.
50 parts by weight of titanium tetraptoxide was applied so that the dry coating film had a thickness of about 0.5 μm and dried.

Next, a catalyst diluted 5 times with MEK (PL-3 manufactured by Shin-Etsu Chemical Co., Ltd.) was sprayed on the coating surface of the polypropylene film on which the coating film was provided, and the catalyst was attached and impregnated with the silicone layer to form the lines on the zinc plate. Pressure laminated so that this coating surface matches the surface with
After heating to 100°C to cure the silicone, the aluminum plate and polypropylene film were peeled off, and the cured silicone rubber was transferred onto the zinc plate and adhered to the zinc plate.

Next, the zinc plate was thoroughly soaked with MEK to dissolve the protective layer, and then the silicone surface was lightly rubbed with a soft cloth to remove the protective layer and silicone layer on the image.

When this zinc plate was used to print on a sheet-fed letterpress printing machine (manufactured by Tokyo Kikai Seisakusho), 10,000 clear prints were obtained.

Example 3 KE77 (trade name manufactured by Shin-Etsu Chemical, silicone rubber) 100 parts by weight KF99 (trade name manufactured by Shin-Etsu Chemical, silicone oil) 100 parts by weight PL-3 (trade name manufactured by Shin-Etsu Chemical, catalyst)
100 parts by weight The above composition was applied onto a polypropylene film so that the dry coating 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, when a polypropylene film with the above-mentioned coating film formed on a zinc plate through the same process as in Example 2 was laminated under pressure so that the coating surfaces matched and heated to 150°C, the silicone had hardened after 30 minutes. Ta. Next, when the zinc plate and polypropylene film were peeled off, the silicone rubber had transferred and adhered to the zinc plate.

Next, the protective layer was sufficiently dissolved in the MEK surface circle of the zinc plate, and then the protective layer and silicone layer on the image lines were removed by gently rubbing the silicone surface with a soft cloth. This zinc plate was used to print on a letterpress sheet-fed printing machine (manufactured by Tokyo Kikai Seisakusho).
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. FIG. 6 is a schematic cross-sectional view of a lithographic 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... Solvent-resistant image, 3... Protective layer made of a solvent-soluble or solvent-swellable substance, 4... Uncured silicone layer, 5... Support, 6... Ink, 2'...An image formed by a part of the substrate, 4'...A cured silicone layer.

Claims (1)

[Claims] 1. A solvent-resistant image line and a solvent-soluble or swellable protective layer are formed on the image line on a substrate, and then the surface containing the protective layer is coated in advance on a support. After pressing the surface of the formed non-photocurable silicone resin layer in an uncured state, the silicone layer is cured, the support is peeled off, and the protective layer is dissolved or swollen with a solvent. A lithographic printing plate characterized in that a solvent-resistant image area and a non-image area consisting of a cured silicone layer are formed on a substrate by removing a protective layer and a silicone layer on the protective layer. Production method. 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.