JPH0311461B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a waterless lithographic printing plate blank for direct printing.

Prior Art An example of a waterless planographic printing plate suitable for printing directly onto a printing material without using a blanket using the planographic printing plate as it is is shown in Japanese Patent Application Laid-Open No. 57-20740. Here, a waterless lithographic printing plate blank for direct printing is obtained by providing an intermediate layer on a rubber elastic body, and further laminating a photosensitive resin layer and a silicone rubber layer in this order. A rubber elastic body provided under the printing layer of the printing plate serves as a blanket in offset printing and provides good ink transfer properties. This intermediate layer is effective as a barrier for the photosensitive resin component, preventing deterioration of plate performance over time and making it possible to obtain a practical printing plate blank for direct printing. using film.

In order to form such an intermediate layer between the rubber elastic body and the photosensitive resin layer, for example, a molded synthetic resin film may be bonded onto the support using an adhesive, or an unvulcanized synthetic resin film may be bonded onto the support. Examples include a method of integrally molding with a rubber layer that serves as a support, a method of extrusion lamination on a rubber layer that serves as a support, or a method of coating a synthetic resin film with a substance having rubber elasticity after dissolving it in a solvent. However, it requires skilled techniques. Also,
It is difficult to form a good intermediate layer due to problems such as film wrinkles and air bubbles. Furthermore, it is difficult to maintain good adhesion between the rubber elastic body and the film.

Purpose of the Invention The present inventors have discovered a method for easily obtaining a good intermediate layer, and a method for this intermediate layer to be effective as a barrier for photosensitive resin components, to prevent plate performance from deteriorating over time, and to prevent deterioration in plate performance over time. It has good solvent resistance against liquids, ink solvents, cleaning agents, etc., and acts as a barrier for the solvent to the rubber elastic body below, and has good adhesion to the rubber elastic body and photosensitive resin component. As a result of intensive studies to obtain an intermediate layer, the present invention described below was achieved.

Structure of the Invention That is, the present invention provides a support comprising a rubber elastic body, a rubber component and a polymer binder cross-linked, and a coating layer having solvent resistance.
The present invention relates to a waterless lithographic printing plate precursor for direct printing, characterized in that it is formed by laminating a photosensitive resin layer and a silicone rubber layer in this order.

Examples of the material for the rubber component of the coating layer of the present invention include, but are not limited to, the following.

Examples of natural rubber and synthetic rubber include polybutadiene rubber, styrene-butadiene rubber, epichlorohydrin rubber, nitrile rubber, acrylic rubber, butyl rubber, urethane rubber, polyester elastomer, polyamide elastomer, and polyether esteramide elastomer. The rubber hardness is preferably 90 or less, more preferably 85 or less, as measured by a spring hardness tester A type shown in JIS K6301-1975.
If the coating layer contains more than 90, it is difficult to obtain a sufficient effect when printing the rubber elasticity of the rubber elastic body through the coating layer. These rubber components may be used alone or in combination of two or more. Furthermore, these rubber components are mixed with a polymer binder or crosslinked before use. A thermosetting resin is preferred as the polymer binder.

The most preferable coating layer is one that contains the same type of rubber component as the underlying rubber elastic body, so that the adhesion to the rubber elastic body is strengthened. Furthermore, by forming a coating layer in which the rubber component and the polymer binder are cross-linked, the solvent resistance is significantly improved, and the application of the developing solution during the preparation of printing plates becomes wider. In addition, it can be widely applied to various inks, ink solvents, ink cleaning agents, etc.

Solvent resistance here means, for example, when measuring mass change in an immersion test, toluene solvent is used to
At 23±2° C. for 1 minute, the mass change rate of a test piece having the coating layer on a rubber elastic body lined with an aluminum plate on one side is 15% or less, preferably 10% or less. If it is more than 15%, the rubber elastic body will swell depending on the developer used during printing plate production, making it impossible to obtain a printing plate with good image reproducibility. Further, during printing, images may be distorted due to ink or ink solvents, and images may be distorted due to ink cleaning agents when removing ink from printing plates.

The thickness of the coating layer is usually 0.5μ or more.
If it is less than 0.5μ, it will not act as a barrier for photosensitive compositions containing low molecular weight components, it will be difficult to prevent changes in photosensitive properties over time, and no barrier effect against solvents can be expected. Also, if the rubber hardness of the rubber elastic body is equal to or higher than the rubber hardness of the coating layer, it may be made quite thick, but if the rubber hardness of the rubber elastic body is smaller than the rubber hardness of the coating layer, do not make it too thick. This is not preferable because the rubber elasticity of the rubber elastic body no longer exerts its effect through the coating layer.

In order to achieve the purpose of the present invention, the coating layer should be 1 to 50 μm.
It is practically preferable to have a thickness of .

In order to form such a coating layer on a rubber elastic body, the coating composition is melted or dissolved in an appropriate solvent, and then melted or dissolved in a suitable solvent.
A coating method using a conventional coater such as a reverse roll, a gravure roll, or a Meyer bar coater, or a rotary coating device such as a Whaler is preferred from the viewpoint of technology and adhesion to the rubber elastic body. Furthermore, the adhesive force can be increased by applying the rubber elastic material onto a matte surface.
By using such a coating method, it is possible to fill in defects such as irregularities in the underlying rubber elastic body.

Materials for the rubber elastic body used in the present invention include natural rubber, and synthetic rubbers include polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, nitrile rubber, acrylic rubber, butyl rubber, epchlorohydrin rubber, urethane rubber, and polyester. Examples include elastomers, polyamide elastomers, polyetheresteramide elastomers, and the like. The rubber hardness of these rubber elastic bodies is preferably 90 or less, more optimally 85 or less, as determined by a spring type A-type hardness tester specified in JIS K6301-1975. Anything over 90 does not play the role of a blanket in offset printing and does not provide good ink transfer.

The thickness of the rubber elastic body is usually about 0.01 to 5 mm. Further, in order to give the rubber elastic body the shape retention required for a printing plate, a metal plate such as an aluminum plate or an iron plate, a plastic film, etc. may be provided under the rubber elastic body.

The photosensitive resin layer is a layer that has the property of being photo-insolubilized or photo-solubilized by irradiation with active light. This layer is uniformly applied onto the coating layer, and its thickness is arbitrary as long as it is in close contact with the coating layer, but it is preferably 100μ or less, and 50μ or less is more useful. If necessary, an anchor coat layer can be provided between the coating layer and the photosensitive resin layer in order to improve the adhesion between the photosensitive resin layer and the coating layer or to prevent halation between the coating layer and the coating layer.

Among the photosensitive resin layers used in the present invention, the photo-insolubilizable ones include those listed below.

(1) A mixture of polyfunctional monomers, oligomers, etc. that have two or more unsaturated groups in one molecule and an appropriate polymer binder.

Typical photopolymerizable groups include acryloyl group, methacryloyl group, acrylamide group,
Examples include maleate ester group, allyl group, vinyl ether group, vinyl thioether group, vinylamino group, glycidyl group, and acetylenically unsaturated group.

(2) A mixture of a photosensitive compound such as an aromatic diazo compound with a suitable polymer binder.

In addition, examples of the photo-soluble photosensitive resin layer used in the present invention include those obtained by mixing inorganic salts of diazo compounds, complexes with organic acids, quinone diazides, etc. with appropriate polymer binders. can.

The silicone rubber layer of the present invention has a thickness of 0.5 to 100μ, preferably 1 to 50μ. Useful silicone rubbers are obtained by sparsely crosslinking linear diorganopolysiloxanes having molecular weights in the tens to hundreds of thousands. Typical silicone rubbers have the following repeating units.

Here, n is an integer of 2 or more. R and R' are alkyl, alkenyl, aryl or cyanoalkyl groups having 1 to 20 carbon atoms. Overall R,
Less than 40% of R' is vinyl, phenyl, vinyl halide, phenyl halide, and R' is
Preferably, 60% or more of the methyl groups are methyl groups. Such silicone rubbers can be sparsely crosslinked by adding organic peroxides, but silicone rubbers that undergo condensation type crosslinking (RTV,
By using LTV), a more preferable silicone rubber layer can be obtained.

A protective film can also be laminated on the surface of the silicone rubber layer forming the surface of the waterless lithographic printing plate blank for direct printing constructed in this manner. Useful protective films have a thickness of 100μ or less, preferably 10μ or less, and examples include films of polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate, cellophane, etc. .

Effects of the Invention The coating layer of the waterless lithographic printing plate blank for direct printing obtained as described above can be obtained by a technically easy coating method using a simple manufacturing device. This makes it possible to provide a coating layer that has good adhesion to the underlying rubber elastic body. In addition, since there is a coating layer that contains a rubber component and has solvent resistance, it is effective as a barrier for the photosensitive resin component and not only prevents deterioration of plate performance over time, but also prevents the development during printing plate creation. The application of the solution becomes wider, and it becomes possible to use an inexpensive developer for automatic processing machines that does not require explosion-proof measures. It can also be widely applied to inks and ink solvents. Furthermore, it becomes possible to use an ink cleaning agent that has good ink cleaning properties but swells the rubber elastic body, and a waterless lithographic printing plate blank for direct printing with greatly improved practicality can be obtained.

Applications The direct printing waterless lithographic printing plate precursor of the present invention can be used to print on, for example, printing substrates with rough surfaces such as unevenness based on fibers such as paper, synthetic resin films and sheets, metals, ceramics, glass, etc. Can also be printed on hard substrates.

The present invention will be specifically explained below using examples, but the present invention is not limited to these examples in any way.

Example 1 A nitrile rubber layer with a thickness of 0.26 mm and a rubber hardness of 70 (Short A) was provided on an aluminum plate with a thickness of 0.24 mm, and a 30% by weight solution of solids having the following composition (the solvent was methyl ethyl ketone/ N-butyl alcohol = 8/2 was applied and dried in hot air at 160°C for 5 minutes to form a coating layer with a thickness of 10 μm.

(a) Nitrile rubber “Nitsupol 1072” (Nippon Zeon) 20 parts by weight (b) Isobutylated melamine resin “L-125-60”
(manufactured by Dainippon Ink & Chemicals) 80 parts by weight The substrate with this coating layer was heated with toluene solvent for 23 minutes.
The mass change rate in the immersion test at ℃ for 1 minute was 1%.

On this coating layer, ester naphthoquinone-1,2-diazide-5-sulfonate (molecular weight approximately 1300) of phenol novolak resin (manufactured by Sumitomo Bakelite: Sumiresin PR50235) with a degree of esterification of 45% is applied.
A 20% by weight solution of Ethicello was applied and dried in hot air at 100°C to form a photosensitive resin layer with a thickness of 2.5μ. On top of this, di-n-butoxy bis(acetylacetonato) titanium (manufactured by Nippon Kagaku Sangyo: Nacem)
A 0.5% by weight solution of Isopar E (manufactured by Etsuso) of Ti) was applied and dried in hot air at 120°C to form an adhesive layer with a thickness of 0.2μ. Furthermore, a 20% by weight Isopar E solution of a silicone rubber composition having the following composition was applied thereon and dried in hot air at 105° C. to form a silicone rubber layer with a thickness of 5 μm.

(a) Polydimethylsiloxane (molecular weight approximately 80,000, less than 2 OH groups) 100 parts by weight (b) Methyltriacetoxysilane 5 parts by weight (c) Dibutyltin acetate 0.2 parts by weight To the printing plate blank obtained as above A negative film was applied to the lamp, and a 2kW metal halide lamp (Iwasaki Electric's idle fin was installed).
2000), and was exposed for 60 seconds from a distance of 1 m. Ethyl carbitol/butyl carbitol =
When rubbed lightly with a cotton pad impregnated with a 1/1 (weight ratio) mixed solvent, the exposed areas are easily removed and the coating layer is exposed, while the silicone rubber layer remains firmly in the unexposed areas. As a result, we obtained a printing plate that faithfully reproduced the negative film. The photosensitive characteristics of this printing original plate did not practically change even after storage at room temperature for one month or storage at 50° C. for seven days after production.

When we conducted a test by printing the obtained printing plate on an aluminum plate using a direct printing machine that prints by rotating the cylinder to which the plate was attached, we found that it was sharp and had good ink coverage. A print with an image was obtained. Furthermore, even when the ink on the printing plate was wiped off with toluene solvent after printing, the image did not deteriorate.

Comparative Example 1 On the nitrile rubber layer lined with the aluminum plate of Example 1, nitrile latex “Nitsupol” was applied.
1571'' (manufactured by Nippon Zeon) and dried for 5 minutes in hot air at 140°C to form a coating layer with a thickness of 10μ. When this substrate was subjected to the same immersion test as in Example 1, the mass change rate was 16%.

A printing plate blank having the same structure and composition as in Example 1 was prepared, except that a photosensitive resin layer, an adhesive layer, and a silicone layer were provided on this coating layer. After exposing this original plate in the same manner as the original plate of Example 1,
When rubbed with a cotton pad impregnated with the same developer (ethyl carbitol/butyl carbitol = 1/1 (weight ratio)), the resulting printing plate had poor image reproducibility. Therefore, when a printing plate was made with ethyl alcohol, a printing plate with good image reproducibility was obtained, so when printing was carried out in the same manner as in Example 1, a printed matter similar to that in Example 1 was obtained, but after printing, the printing plate When cleaning the ink, the image on the printing plate was damaged by toluene.

Example 2 A 27% by weight solution of solids having the following composition (solvent: methyl ethyl ketone/n-butyl alcohol = 9/1) was applied onto the nitrile rubber layer lined with the aluminum plate of Example 1. It was dried in hot air at °C for 5 minutes to form a coating layer with a thickness of 20 μm.

(a) Nitrile rubber “Nitsupol 1072” (Nippon Zeon) 25 parts by weight (b) Isobutylated melamine resin “L-121-60”
(manufactured by Dainippon Ink and Chemicals) 75 parts by weight When the substrate having this coating layer was immersed in the same test as in Example 1, the mass change rate was 4%.

A printing plate was prepared on this coating layer in the same manner as in Example 1, and when printing was carried out in the same manner as in Example 1, good printed matter was obtained. Furthermore, the image did not deteriorate even when the ink on the printing plate was wiped off with toluene solvent during printing and after printing.

Comparative Example 2 A printing plate original plate was produced in exactly the same manner as in Example 1, except that the coating layer in Example 1 was changed to a substrate made by laminating a 3μ thick polyester film (Toray's "Lumirror") with a rubber adhesive. did. When pasting the polyester film together, there may be some wrinkles,
Due to the presence of air bubbles, when the photosensitive layer, adhesive layer, and silicone layer were coated, thickness unevenness occurred in some areas. When this original plate was exposed and plate-made in the same manner as in Example 1, a printing plate was obtained that had portions with poor image reproducibility due to thickness unevenness. When this printing plate was subjected to printing in the same manner as in Example 1, the polyester film of this printing plate was misaligned with the underlying nitrile rubber layer and wrinkled due to the shear stress between the printing plate and the substrate. Due to this problem, good printed matter could not be obtained.

Claims (1)

[Claims] 1 A photosensitive resin layer and a silicone rubber layer are laminated in this order on a support formed by crosslinking a rubber component and a polymer binder on a rubber elastic body and provided with a coating layer having solvent resistance. A waterless lithographic printing plate blank for direct printing, which is characterized by: