JPH0329168Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a support for a lithographic printing plate, and particularly to a support for a lithographic printing plate that is inexpensive and has excellent water resistance and dimensional stability.

As supports for planographic printing plates, metal plates such as aluminum and zinc, plastic films such as polyethylene terephthalate and polyvinyl chloride, and paper are used. Since metal plates and plastic films have excellent mechanical strength, water resistance, and dimensional stability, they are used as supports for lithographic printing plates that are desired to have a long printing life. On the other hand, paper is inferior to the above-mentioned supports in terms of mechanical strength, water resistance, dimensional stability, etc., but because of its low cost, it is used as a support for lithographic printing plates that require only a small number of printing sheets. .

In recent years, supports for lithographic printing plates that are inexpensive and have excellent water resistance have come to be used, such as the one shown in Figure 1, in which both or one side of a paper base is coated with a water-resistant resin such as polyethylene. . This support has superior water resistance, dimensional stability, etc. compared to paper supports, and has a long printing life, but is still inferior to plastic films such as polyethylene terephthalate. For example, in the case of polyethylene-coated paper, dampening water or its vapor gradually passes through the polyethylene layer during printing and wets the paper base, and the polyethylene itself has some elasticity, so the printing plate The disadvantage is that it stretches and impairs dimensional stability.

An object of the present invention is to provide a support for a lithographic printing plate that is inexpensive, has excellent water resistance, and can improve dimensional stability and printing durability.

The object of the present invention is achieved by providing a layered structure in which a flexible metal foil layer is provided on at least one side of a paper substrate, and a water-resistant resin layer is further provided on at least the surface of the metal foil layer.

The present invention will be explained below with reference to the drawings.

FIG. 2 is a sectional view showing an example of the lithographic printing plate support of the present invention. In the figure, 1 is paper base, 2 and 3
is a water-resistant resin layer, and 4 and 5 are flexible metal foil layers. The present invention is characterized by providing this metal foil layer. The presence of the metal foil layer serves as a complement to the resin layer for water resistance and can prevent dampening water and the like from penetrating into the paper substrate during printing. A,
In both Examples B and C, a printing image forming layer is usually provided on the water-resistant resin layer 2. Among these examples, examples B and C, in which a water-resistant resin layer is also provided on the back surface, are suitable for printing plates that undergo dipping treatment in the plate-making process, and example B is practically sufficient.

In the lithographic printing plate support of the present invention, various resins can be used to form the water-resistant resin layer, such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyvinyl acetate, cellulose acetate, etc. However, polyethylene is very inexpensive, and when forming a hydrophilic image forming layer on the resin layer, it is possible to use simple pretreatment such as corona discharge treatment without needing to undercoat the adhesive layer. This is advantageous in that it can be coated with a polyurethane resin and the image forming layer can be strongly adhered to the surface of the support.
Aluminum is the most suitable metal for forming the flexible metal foil layer, but zinc and the like can also be used. Wood pulp is usually used as the fiber forming the paper base, but synthetic pulp or a mixed pulp thereof may also be used.

The thickness of these constituent layers is not particularly limited, but
Usually paper base is about 70~250μ, metal foil layer is about 5~
50μ, and the water-resistant resin layer is used in the range of about 20-80μ. The thickness of the support for lithographic printing plates is usually about 100 to 300 μm.

In the present invention, the water-resistant resin layer contains a reflectance improver (e.g., titanium oxide), a fluorescent brightener, a hue adjuster (red, blue, and violet dyes, pigments, etc.), and a black agent (e.g., carbon black). ), an antistatic agent, etc. can be contained as necessary.

The lithographic printing plate support of the present invention can generally be produced by the following method. Apply adhesive to the surface of the paper base, adhere metal foil on top of this, apply adhesive to the surface of the metal foil, or apply appropriate treatment such as corona discharge treatment, and then apply water-resistant resin to the solution. It can be obtained by applying it in the form of If necessary, if a water-resistant resin layer is provided on the back of the paper base,
A water-resistant resin solution may be applied after the paper surface is subjected to a treatment such as corona discharge treatment or an adhesive is applied.

The support of the present invention is useful for various lithographic printing plates. For example, a printing plate using a diazo compound, a photosensitive resin, etc., a hardening development type printing plate using a photosensitive silver halide emulsion, a printing plate using a silver image formed using a silver complex diffusion transfer method as an ink receptive plate, Silver halide areas obtained by ordinary photographic methods can be converted into ink-receptive areas and used in printing plates and the like.

The lithographic printing plate support of the present invention is a metal plate support,
It is cheaper than plastic film support,
Moreover, it not only has water resistance, dimensional stability, and printing durability comparable to or better than plastic film, but also has flexibility and cutting suitability similar to paper supports, so it can be used in long rolls for automatic plate making machines, etc. It is particularly effective for printing plates that are loaded and used. When a lithographic printing plate material is loaded into an automatic plate-making machine in the form of a long roll, it is cut into a predetermined size during the plate-making process. This is undesirable because it causes significant wear and may result in poor cutting. When the support of the present invention is used, such inconveniences hardly occur.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional lithographic printing plate support.
FIG. 2 is a sectional view showing an example of the lithographic printing plate support of the present invention. In the figure, 1 is a paper base, 2 and 3 are water-resistant resin layers, and 4 and 5 are flexible metal foil layers, respectively.

Claims (1)

[Scope of utility model registration request] In a layer configuration in which a flexible metal foil layer is provided on at least one side of the paper substrate, and a water-resistant resin layer is further provided on at least the surface of the metal foil layer, after surface modification of the resin layer, an image forming layer is provided. A support for lithographic printing plates.