JP3448918B2 - Printing film for plate making - Google Patents

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 two layers, a photosensitive layer and a supporting layer, are basic constituent layers, and the supporting layer is a layer having cellulose acetate as a surface layer. The photosensitive layer is nitrocellulose, carbon black, binder resin,
Etc., and additives such as a water repellent and a cross-linking agent may be added if necessary.

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 support layer may be a layer of cellulose acetate only, or a layer of cellulose acetate may be laminated on the surface of the PET film or PP film.

The surface of the cellulose acetate layer may be partially saponified.

The photosensitive layer is formed with a thickness not more than 1.5 times the depth of focus of the writing optical system.

[0015]

EFFECT OF THE INVENTION By using the film having the above structure,
When the pits are formed by the laser beam, a hydrophilic cellulose acetate layer appears on the bottom surface of the pits, and the aqueous ink can be retained in the pits. Further, since the photosensitive layer is hydrophobic, it is possible to prevent ink from adhering to the surface of the photosensitive layer.

[0016]

[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 to the surface of a cellulose triacetate support layer (thickness 100 μm) having a partially saponified surface as a photosensitive layer with an applicator at 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, pits were formed with a laser having a focal elongation of 10 μm and printed with a water-based ink to evaluate stains on the printed matter and sharpness of the printed matter.

The results were good.

[0020]

Comparative Example The same evaluation as in Example 1 was carried out using a polyethylene film as the support layer.

The result was a bleed on the printed surface.

Claims (5)

(57) [Claims] 1. A printing film for laser plate making, which comprises two layers, a photosensitive layer and a support layer, as basic constituent layers, wherein the photosensitive layer comprises nitrocellulose, carbon black, and
A layer containing a fine aromatic polyester resins, plate making printing film the supporting layer is characterized in that a layer to the surface layer of cellulose acetate. 2. The support layer is a PET film or PP
The printing film for plate-making according to claim 1, wherein a layer of cellulose acetate is laminated on the surface of the film. 3. The plate-making printing film according to claim 1, wherein a water repellent agent is added to the photosensitive layer. 4. The printing film for plate-making according to claim 1, wherein the water repellent agent is a silicone compound, a fluorine compound, or a copolymer or a graft product thereof with another component. 5. A photosensitive layer and a support layer are two basic layers, the support layer is a layer having cellulose acetate as a surface layer, and pits are formed in the photosensitive layer by laser irradiation.
A printing film for plate making, characterized in that the above-mentioned supporting layer appears on the bottom surface of the pit .