JPS6255516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new lithographic printing plate, and particularly to a lithographic printing plate that can be provided at low cost.

A lithographic printing plate is a thin plate with a thickness of 0.1 to 0.5 mm, and has an image area and a non-image area on the same plane. The image area requires chemical properties such as lipophilicity and water repulsion, and the non-image area requires chemical properties such as hydrophilicity, water retention, and ink repulsion. The image area usually consists of an organic photosensitive layer, and the non-image area consists of metal. Currently known metals for the non-image area are aluminum and zinc, which are combined with the image area of the organic photoresist film. Stainless steel, chrome, etc. are plated with copper, and a combination of metals is used, such as copper plating on the printed areas and stainless steel, and chrome on the non-printed areas. As described above, various types of printing plates are used depending on the combination of materials for the non-printing areas and printing areas, and a printing plate that suits the purpose is adopted in terms of workability, economy, number of copies, etc. Among these plate types, PS plates, in which an aluminum plate is used as a support and coated with a photosensitive resin, are currently the most popular. However, in the era of high energy prices due to the dramatic rise in crude oil prices, it must be said that the use of aluminum, which consumes a large amount of electricity during refining, is a major disadvantage from an industrial perspective in terms of energy conservation.

The present invention does not use aluminum,
The purpose is to provide high-performance planographic printing plates using inexpensive materials.

As a result of intensive research on the combination of various metal plating surfaces with photosensitive resin layers, the present inventors discovered that the nickel plating surface formed on iron foil made by electroforming can be used as the non-image area of a lithographic printing plate. , we have completed the present invention.

The gist of the present invention is that the thickness 5
A planographic printing plate characterized by coating iron foil with a thickness of ~150μ with nickel plating with a film thickness of 0.1 to 5μ, and coating the plated surface with a photosensitive resin, where the nickel plating surface covers the non-image areas. The photosensitive resin layer becomes the image area.

Using iron foil as a base material is advantageous in terms of cost and strength, but when using an iron plate, it is heavy and the cut surface of the thin iron plate is like a razor blade. There are problems such as dangerous handling. Therefore, in the present invention, as a particularly advantageous material, extremely thin iron foil is produced by electroforming from an electrolytic solution containing iron, and then nickel plated to form a support for a lithographic printing plate.

The iron foil produced by the electroforming method described above differs from the iron foil produced by rolling, and has the following characteristics. In other words, it has features such as an extremely thin thickness, a cut surface that does not look like a razor blade, making it safe to handle, and a rough surface created by the iron buildup due to plating. It can be used as is without surface preparation such as ball polishing and anodizing like aluminum plates.
The thickness of the iron foil is 5-150μ, preferably 10-100μ. Because of its ultra-thin thickness, it is also characterized by its light weight, unlike iron plates. Iron foil obtained by electroforming is oxidized and rusts easily if left as is, so it is preferable to apply nickel plating to both sides. The thickness of the Nickelmetsuki layer is
A range of 0.1 μ to 5 μ is preferable, and within this range, the surface roughness of the iron foil obtained by electroforming is not impaired and it has sufficient printing durability. The support for lithographic printing plates is made of nickel plating on iron foil, so it is a material that does not expand or contract.
Its coefficient of thermal expansion is about half that of aluminum, so its dimensional accuracy is stable depending on the temperature.

A lithographic printing plate is made by directly applying a photosensitive resin to the nickel plated surface, but after the plated surface is previously subjected to chemical conversion treatment or polymer coating treatment to form an extremely thin permanent hydrophilic film on the surface,
It is also possible to apply a photosensitive resin. This type of treated film not only prevents background smearing but also improves adhesion with diazo photosensitive liquids such as diazo resin.
Preservability can be improved. A water-soluble polymer electrolyte can be used as the polymer coating material.

Nickel-plated iron foil can be adjusted to a plate thickness that improves workability by laminating an inexpensive reinforcing material on the back side with or without the nickel-plated surface. As such materials, water-resistant paper, cloth, nonwoven fabric, plastic sheet, synthetic paper, etc. can be used. Examples of the plastic sheet include polyethylene, polypropylene, vinyl chloride, nylon, and polyester. When such a material is laminated to iron foil with a suitable adhesive, it has sufficient strength as a printing plate. Of course, the reinforcing material may be directly laminated onto the iron foil.

A planographic plate can be obtained by applying nickel plating to iron foil produced by electroforming and coating it with a photosensitive resin, and as the photosensitive resin, known ones can be used. For example, for negative types, photosensitive materials such as dichromic acid colloid photosensitive solution, diazo resin, paraquinone diazide, and polyvinyl cinnamate are used, and for positive types, photo-solubilized photosensitive materials using orthoquinone diazide are used. be able to. Using these photosensitive resins
It can be used as a PS version or a one-point version.

The lithographic printing plates obtained as described above have the same quality and are much cheaper than printing plates using aluminum plates, so they can be used for large-scale applications such as newspaper offset printing. This plate material is suitable for

Next, the present invention will be specifically explained with reference to Examples.

Example 1 "Ironfoil" manufactured by Toyo Kohan Co., Ltd. (iron foil manufactured by electroforming method, iron foil thickness 50 μm, nickel plating thickness 2 μm) was used, and one side of the iron foil was coated with an adhesive of 100 μm. After laminating a thick polyester film, it was degreased with alkali, and then a positive type photosensitive liquid ("Sanwaipon" manufactured by Koyosha Research Institute) was applied to the other surface and dried at 70° C. for 2 minutes.

A positive film was placed in close contact with the photosensitive surface obtained in this way, and a 3KW high-pressure mercury lamp was irradiated from a distance of 70cm for 45 seconds.The plate was then washed with alkaline solution, and the photosensitive resin in the exposed area was washed out. Ta.
A lithographic printing plate was obtained by washing with water and drying. When this lithographic printing plate was used for printing with an offset printing machine, clear printed matter was obtained.

Example 2 "Ironfoil" manufactured by Toyo Kohan Co., Ltd. (iron foil manufactured by electroforming, thickness of iron foil 30μ, thickness of nickel plating 1.5μ) was used, and one side of the iron foil was coated with adhesive. 210 μ thick styrene-based synthetic paper (“Peach Coat WG-220” manufactured by Nisshinbo Co., Ltd.)
After laminating, it was degreased with alkali, and then a negative type photosensitive liquid ("Sanwaipon Negative Type" manufactured by Koyosha Research Institute) was applied to the other surfaces, and it was heated at 70℃ for 2 hours.
Dry for a minute.

A negative film was printed on the photosensitive surface thus obtained, a developing lacquer was applied, and a finishing rubber coating was applied to obtain a lithographic printing plate. When this lithographic printing plate was used for printing with an offset printing machine, clear printed matter was obtained.

Claims (1)

[Scope of Claims] 1 Nickel plating with a thickness of 0.1 to 5 μm is applied to iron foil with a thickness of 5 to 150 μm manufactured by electroforming,
A lithographic printing plate characterized in that the plated surface is coated with a photosensitive resin. 2. The lithographic printing plate according to item 1 above, wherein a photosensitive resin is applied to the nickel-plated surface of iron foil, and a reinforcing material is laminated to the back side of the iron foil with or without the nickel-plated surface.