JPH03211093A - Planographic printing base plate for current supply plate making - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lithographic printing original plate for electrical plate making, and more specifically, by selectively applying electrical pulses from needle electrodes of an electrical thermal transfer printer. This invention relates to a lithographic printing original plate that can be made without using an ink ribbon or the like.

[Prior art]

A typical example of an original printing plate for office use is one in which a hydrophilic surface layer is formed on a water-resistant substrate (a surface-structured or electrophotographic lithographic printing original plate). Drawing/printing or toner development is generally carried out on the layer by taking advantage of the fact that ink from ink ribbons for printers and typewriters and toner for electrophotography are both hydrophobic.

By the way, recently, as shown in Japanese Unexamined Patent Publication No. 1-123795, there is a method that has a layer of a conductive material, a layer of a hydrophobic material that melts with heat, and an inorganic electrical resistance layer, and when a current flows through the layer of the conductive material. 2. Description of the Related Art There is known a current-carrying lithographic printing original plate (current-carrying lithographic printing original plate) in which a hydrophobic material that melts with heat is thermally diffused into an electrically resistive layer, and the surface of the electrically resistive layer is converted to hydrophobicity. The use of this original plate has the advantage that the original plate can be easily made directly by an electric thermal transfer type printer without using an intermediate medium such as an ink ribbon.

However, in the original plate disclosed in JP-A-1-123795, what is in contact with the needle electrode is an inorganic electrically resistive material layer, and this surface layer is made hydrophilic by a hydrophilic treatment before printing. Unless it is easily susceptible to corrosion, it cannot be used as an original plate for lithographic printing. Therefore, the needle-like electrode is easily worn out, and there is a problem in the durability of the needle-like electrode. In addition, this type of lithographic printing original plate uses approximately 90% of the thermal energy generated during plate making.
1 is generated at the interface of the layers, and the remaining 10% is generated at locations other than the interface, so there is still the problem that the power consumption required for momentum and plate making tends to be high.

[Problem to be solved by the invention]

The present invention provides a lithographic printing original plate for electrical plate making that can perform plate making with low power consumption and obtain high resolution without abrading needle electrodes or using intermediate media such as ink ribbons. be.

[Means to solve the problem]

The lithographic printing original plate for electrical platemaking of the present invention comprises a substrate having three electrically resistive layers, a conductive layer thereon, and a surface layer having a hydrophilic component and a hydrophobic component that melts with heat.
When a current flows through the conductive layer through the substrate serving as the electrical resistance layer, the heat generated between the two causes the hydrophobic component contained in the surface layer to thermally diffuse, converting the surface region into a hydrophobic region. It is characterized by being something.

The invention will be explained in more detail below with reference to the accompanying drawings.

FIG. 1 shows a lithographic printing original plate for electrical platemaking (hereinafter referred to as “
FIG. 2 is a schematic diagram illustrating how electrical platemaking is performed using a printing master plate (sometimes abbreviated as a "printing master plate" or "master plate").

The printing original plate 1 is composed of an electrically resistive substrate 2, a thin conductive layer 3 on the substrate, and a surface layer 4 coated on the conductive layer. FIG. 1 also shows a needle electrode 5 and a ground electrode 6 of the current transfer printer. Of course printing original plate 1
can also be used with any printer that has multiple needle electrodes.

The base 2 preferably has a thickness of up to about 502 parts and exhibits an electrical resistance of 102 to 103 Ω,
Polycarbonate containing conductive carbon can be used.

The conductive layer 3 may be formed by depositing any conductive material such as aluminum or zinc. The conductive layer is preferably metal, but may be any other conductive material. Thickness is 0.1~
Approximately 2 voices is appropriate.

The surface layer 4 includes (1) a thermoplastic resin such as a polyamide thermoplastic resin or a polyvinyl-butyl thermoplastic resin as a binder, (2) an inorganic pigment that becomes hydrophilic by desensitization treatment such as zinc oxide, and ( 3) A mixture with a thermoplastic hydrophobic substance such as wax or fatty acid is applied to a thickness of several microns.

Now, when an electrical pulse is applied from the needle electrode 5 of the printer to the base 2 of such a printing original plate, a current flows through the base 2, which is an electrically resistive layer, to the conductive layer 3. In the figure, 6
7 represents the return path electrode, and 7 represents the current flowing from the needle electrode 8 to the return path electrode 6. At this time, heat is generated at the interface between the acicular electrode 5 and the substrate 2, which is a resistance layer, inside the substrate 2, which is a resistance layer, and at the interface between the substrate 2, which is a resistance layer, and the conductive layer.

As shown in FIG. 2, this heat causes the thermoplastic resin and thermoplastic hydrophobic substance in the surface layer 4 to melt and cover the surface, creating a hydrophobic region 8 to which ink is attached, and making a plate. . Due to the desensitization process, other areas become hydrophilic and ink-repellent areas.

〔Example〕

Examples are shown below, where parts are based on weight.

Example 1 Using a mixture of 60 parts of polycarbonate resin, 40 parts of conductive carbon, and 900 parts of toluene/methylene chloride (1:1 mixed solvent), a resistance layer (substrate) with a thickness of about 35 μm was provided, and a resistance layer (substrate) of about 0.1 m thick was provided on this. A thick aluminum vapor deposition layer was formed to serve as a conductive layer.

On top of this, n-BMA (n-butyl methacrylate) 20 parts Zinc oxide 80 parts Behenic acid 0.2 parts Silicone oil 0.8 parts IPA
0.6 parts toluene
A surface layer approximately 4 μm thick was formed using a mixture consisting of 120 parts.

The sample of the example was plate-made using a modified commercially available electric printer (manufactured by IBM), and then printed using a Ricoh lithographic printer AP-
3700 (manufactured by Ricoh Co., Ltd.), good printed matter without background smearing was obtained.

〔Effect of the invention〕

The printing original plate of the present invention can provide a high-resolution printing image, has good printing durability, is easy to perform original plate preparation processing and plate making, and can be made with low power consumption.

Furthermore, wear of the needle electrode can be reduced, and highly reliable plate making can be performed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing plate making using the lithographic printing plate for electrical plate making according to the present invention. FIG. 2 is a schematic diagram of the printing original plate after receiving electric current from the printer needle electrode. 1...Printing original plate 2...Base (electrical resistance layer) 3...Conductive layer 4...Surface layer 5...Acicular electrode 6...Ground electrode (return electrode) 7...Current 8.Hydrophobic region

Claims (1)

[Claims] (1) It consists of a substrate that becomes an electrical resistance layer, a conductive layer thereon, and a surface layer having a hydrophilic component and a hydrophobic component that melts with heat, and the electrically conductive layer passes through the substrate that becomes the electrical resistance layer. A lithographic plate for electrical platemaking, characterized in that when an electric current flows through the two, the hydrophobic components contained in the surface layer are thermally diffused by the heat generated between the two, and the surface area is converted into a hydrophobic area. Original printing version.