JPH0781026A - Process printing film - Google Patents

Abstract

PURPOSE:To prevent ink from adhering to a surface of a photosensitive layer and hold the ink inside a pit only, which is formed in the photosensitive layer, by forming two layers of the photosensitive layer and a support layer as a basic structure and having a hydrophobic layer formed on the surface of the photosensitive layer. CONSTITUTION:A process printing film has two layers of a photosensitivc layer and a support layer as a basic structure and has a hydrophobic layer formed on the surface of the photosensitive layer, and the photosensitive layer is formed of nitrocellulose, carbon black, a bonding resin and the like. It is preferable that the nitrocellulose has 11.5 to 12.2% of the nitrogen content and 1 to 1/8 sec of a solution viscosity. The carbon black makes dispersion easy. A polyester resin may be used as the bonding resin, but an aromatic polyester is preferable. A hydrophilic ink holding layer is formed on the support layer made of PET and the like as a thin film of AI, ITO, SiO2 and the like, The hydrophobic layer may be made of a material such as paraffin wax, etc., which is scattered together with the photosensitive layer by laser heating.

Description

Detailed Description of the Invention

[0001]

[Industrial application] The present invention relates to a printing film for plate making.

[0002]

2. Description of the Related Art A printing film for plate-making uses a laser beam to hold ink in pits formed on it, and transfers the array pattern of the pits to paper to produce a printed matter. The original plate. In order to hold the ink in the pits, the ink is applied on the film on which the pits are formed, and then the excess ink adhering to the surface is scraped off.

At this time, if the affinity between the surface of the photosensitive layer and the ink is high, the excess ink on the surface of the photosensitive layer cannot be completely removed, and the printed matter is stained. Since an aqueous material is used as the ink, in order to solve this problem, the hydrophobicity of the photosensitive layer itself forming the surface on which the ink is applied is increased.

However, if the photosensitive layer is too hydrophobic, the ink will not be sufficiently retained in the pits and the printed matter will be incomplete.

In the past, in order to solve this problem, it was necessary to control the hydrophobicity and characteristics of the photosensitive layer so that the printed matter became clear.

[0006]

The problem to be solved by the present invention is to prevent ink from adhering to the surface of the photosensitive layer and to retain the ink only inside the pits formed in the photosensitive layer. It consists in constructing a printing film.

That is, a printing film for plate making is characterized in that it has a basic structure of two layers of a photosensitive layer and a support layer and has a hydrophobic layer on the surface of the photosensitive layer. The photosensitive layer is nitrocellulose,
It is composed of carbon black, binder resin, etc.,
You may add additives, such as a water repellent and a crosslinking agent, as needed.

Nitrocellulose has a nitrogen content of 10 to 40.
%, The degree of polymerization varies, but the nitrogen content is 11.5-1.
2.2%, solution viscosity of 1 to 1/8 second is preferable,
You may mix 2 or more types as needed.

In order to facilitate the dispersion of carbon black, color chips or color paste in which carbon black is dispersed in nitrocellulose may be used.

As the binding resin, there is polyester resin, but aromatic polyester is preferable.

As the water repellent, a silicone compound, a fluorine compound and a copolymer or a graft of these with other components are used, and the addition amount thereof is such that the surface wetting index is 36 dyn /
It is set to be not more than 0.1 cm based on 100 parts of the solid content of the coating solution.
1 to 5 parts, preferably 0.2 to 2 parts are used.

The hydrophilic ink retaining layer is formed as a thin film of Al, ITO, SiO ₂ or the like on a support layer such as PET. Forming means is vacuum deposition, sprinkling, coating,
It is a known means such as laminating.

The hydrophobic layer may be paraffin wax or any other material that scatters together with the photosensitive layer by laser heating.

[0014]

EFFECT OF THE INVENTION By using the film having the above structure,
When forming pits with a laser beam, the outermost hydrophobic layer is also decomposed and melted along with the photosensitive layer at the light-irradiated portion, and the photosensitive layer appears on the side surface of the pit, and the aqueous ink can be retained in the pit. Like On the other hand, the surface not exposed to light has a hydrophobic layer on the surface, which can prevent ink from adhering to the surface.

[0015]

[Example] Nitrocellulose RS1 / 4 (manufactured by Daicel Chemical Industries, Ltd., solid content 70%) 7.7 parts, color paste ANP-C-903 black (manufactured by Toyo Ink, carbon black 12%, nitrocellulose 18%) 24.
6 parts, polyester resin Byron 20SS (manufactured by Toyobo,
Solid content 30%) 43.3 parts, cross-linking agent Super Beckamine L-105-60 (manufactured by Dainippon Ink, solid content 60%)
5.4 copies, BYK CATALLYST 450 (BYK
Manufactured by the company, solid content 40%) 0.4 parts, methyl ethyl ketone 1
8.7 parts was dissolved and mixed to obtain a coating liquid.

This coating solution was applied as a photosensitive layer on the surface of the polyethylene terephthalate film (thickness 100 μm) of the support layer with an applicator to a thickness of 7 μm.
It was dried at 0 ° C. for 3 minutes.

Paraffin wax having a thickness of 0.5 μm was coated as a hydrophobic layer on the surface of the photosensitive layer of the obtained film. Using this film, the focal length of 10 μm
Then, pits were formed on the sheet and printed with a water-based ink to evaluate stains on the printed matter and sharpness of the printed matter.

The results were good.

[0019]

Comparative Example The same evaluation as in Example 1 was performed without the hydrophobic layer.

The result was that the printed surface had bleeding.

Claims (1)

[Claims] 1. A printing film for plate-making, comprising a photosensitive layer and a supporting layer as a basic structure and having a hydrophobic layer on the surface of the photosensitive layer.