JPH07232485A - Lithographic printing original plate and process printing method employing the same - Google Patents

Abstract

PURPOSE:To obtain a new waterless lithographic printing original plate at low cost by respectively providing an oleophilic coating film on one side of the outer surface of a layer having a foaming agent dispersed in the layer of a high polymeric material and a base sheet on the other surface. CONSTITUTION:The lithographic printing original plate 1 is constituted of respectively providing an oleophilic coating film 3 on one side of the outer surface of a layer 2 having a foaming agent dispersed in the layer of a high polymeric material and a base sheet 4 on the other surface. While transporting the original plate 1, the foaming agent dispersed layer 2 is selectively given the thermal energy of a thermal head heating body or the like through the oleophilic coating film 3, and the foaming agent dispersed layer 2 is locally exploded and heat decomposition-reacted to whereby form a foamed part. The printing plate obtained in this way is mounted on the plate drum in the form of the foamed part side to be a plate surface, and water ink is supplied onto the printing plate surface so as to allow water ink to selectively be stuck to the foamed part, and then printing paper is put into direct contact with the water ink-stuck printing plate for obtaining a printed matter. As a result, a lithographic printing original plate can easily be manufactured. Also, the inking system becomes simple.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate precursor suitable for using a water-based ink, and a plate-making printing method using the same.

[0002]

2. Description of the Related Art Heat-sensitive lithographic printing plate precursors and letterpress / intaglio printing plate precursors containing a foaming agent in a thermoplastic resin layer are used in the field of office printing because they are relatively easy to perform plate-making printing. (Japanese Patent Application Laid-Open No. 56-42653, Japanese Patent Application Laid-Open No. 6-26356)
3-2725253, JP-A-63-147690, JP-A-3-110164, etc.). Further, a large number of heat-sensitive stencil base papers in which a foaming agent-dispersed layer itself or a porous support is attached thereto have been proposed (JP-A-49).
-52015).

Here, among these, a commercially available plate making machine is used to perform plate making on the stencil sheet, but in the plate making of the printing original plate, infrared rays are irradiated in a state where the original sheet is brought into close contact with the original sheet and the image of the original sheet is imaged. In general, a means for foaming a foaming agent has been adopted. That is, it is the actual situation that the same means as those for making stencil sheets have not yet been adopted in the plate making of the heat sensitive printing plate.

As is well known, the lithographic printing method is most widely used in the field of office printing. In the conventional lithographic printing method (for example, offset printing method), usually, a printing plate is used in which the image part is lipophilic and the non-image part is hydrophilic, and an oily high-viscosity ink is supplied to the image part and After transferring to a blanket, it is transferred to printing paper. In addition, the inking system has a large number of rows of ink rollers because it is necessary to supply high-viscosity ink to the printing plate with a low-viscosity ink, which also causes high cost of printed matter. It is also becoming.

In order to prevent the ink from adhering to the non-image area of the printing plate, a method of supplying dampening water to the non-image area is used. This dampening water emulsifies the ink. It also has the inconvenience of being lost. Of course, a waterless planographic printing method in which a water-repellent / oil-repellent layer is provided on the surface of the original plate is also known, but an expected copy has not been obtained. Furthermore, in the production of the printing plate, as described above, a dedicated plate making device for optically exposing is necessary, and a large and expensive plate making device becomes a problem in terms of space and cost. However, there is an inconvenience that it is impossible to easily make a plate on a printing machine. Furthermore, since a large pressing force is required for the ink transfer from the blanket to the printing paper, the plate-making printing apparatus has the drawbacks of being tough and large, and increasing noise and power consumption.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a completely new lithographic printing plate precursor and a plate-making / printing method using the same, which can solve many of the above problems at once. .

[0007]

A first aspect of the present invention is a lithographic printing plate precursor comprising a layer of a polymeric material in which a foaming agent is dispersed, and a lipophilic coating on one side and a base sheet on the other side. It is characterized by being provided.

A second aspect of the present invention is a method for making a lithographic printing plate, wherein a lipophilic coating is passed through a foaming agent dispersion layer while transporting the original plate obtained in the first aspect of the present invention to obtain a thermal head heating element or the like. It is characterized in that the foaming portion is formed by selectively applying heat energy to locally explode and thermally decompose the foaming agent dispersion layer. This foam portion is where the image portion is formed.

A third aspect of the present invention is a lithographic printing method, in which the printing plate obtained in the second aspect of the present invention is mounted on a plate cylinder with the foamed portion side facing the plate surface, and a water-based ink is applied to the surface of the printing plate. Is supplied to selectively adhere the water-based ink to the foaming portion, and the printing paper is directly contacted with the printing plate to which the water-based ink is adhered to obtain a printed matter.

The present invention will be described in more detail below with reference to the accompanying drawings. FIG. 1 shows a typical example of the lithographic printing plate precursor 1 of the present invention. A thin lipophilic coating 3 is applied on the upper surface of the foaming agent layer 2, and a base sheet 4 is formed on the lower surface of the foaming agent layer 2. Is affixed. Examples of the material of the base sheet 4 include paper wet-reinforced with a resin, a film of a synthetic resin such as polyethylene terephthalate, and metal vapor-deposited paper vapor-deposited with aluminum or the like. The base sheet 4 has a thickness of about 20 to 20.
Those having a thickness of 0 μm are preferably used.

The foaming agent layer 2 can be made, for example, by dissolving a polymer material such as styrene resin, vinyl resin or synthetic rubber in a solvent such as xylene and adding a foaming agent thereto. Any polymer material may be used as long as it is soluble in a solvent and has film-forming properties, but a thermoplastic resin is preferable. If it is a thermoplastic resin, it does not interfere with the increase in volume during foaming by softening during plate making.

Examples of the thermoplastic resin include polystyrene, styrene resin such as styrene-acrylic acid ester copolymer, low melting point polyamide resin, polyacrylic acid ester, polyester resin, vinylidene chloride, acetal resin and the like.

As the foaming agent, the following inorganic ones,
An organic type can be exemplified, but an organic type foaming agent is preferable in order to obtain high resolution. (1) Inorganic foaming agent Zinc peroxide (ZnO ₂ ) (explosion) 212 ° C Calcium peroxide (CaO ₂ ) (explosion) 275 ° C Barium peroxide (BaO ₂ ) (decomposition) 450 ° C Sodium peroxide (Na ₂ O) ₂ ) (Decomposition) 460 ° C Sodium hydrogen carbonate (NaHCO ₃ ) (Decomposition) 270 ° C Potassium hydrogen carbonate (KHCO ₃ ) (Decomposition) 120 ° C Calcium azide (CaCN ₃ ) ₂ (Explosion) 150 ° C (2) Organic foaming agent diazoaminobenzene _{(explosion) 99-100 ℃ C 6 H 5 N} = NNHC 6 H 5 Benzenesulfonyl hydrazine _{(explosion) 103-104 ℃ C 6 H 5 -SO} 4 -NN-NH 2

Here, an example of a specific formulation of the foaming agent layer will be shown. Xylene 650 ml Styrene polymer 130 g Magnesium sulfate 60 g Barium sulfate 30 g Calcium sulfate 80 g Foaming agent 32 g As a binder, for example, styrene polymer is sufficiently dissolved in xylene as a solvent, and the foaming agent is dispersed therein. Further, powders of magnesium sulfate, barium sulfate, calcium sulfate and the like may be mixed alone or in combination.

The thickness of the foaming agent layer 2 constituting the original plate 1 is preferably about 5 to 100 μm, more preferably 5 to 100 μm.
It is 30 μm.

Among the resins used in the foaming agent layer 2, polystyrene, styrene-acrylic acid ester copolymer, polyacrylic acid ester and the like exhibit lipophilicity by themselves, and the surface of the foaming agent layer 2 is further hydrophilic. It is desirable to coat the oil film 3. Examples of the material of the lipophilic coating 3 include carnauba wax, paraffin wax, ceresin wax, low molecular weight polyethylene, and fatty acids such as stearic acid.

FIG. 2 shows how the plate making method of the present invention is carried out. Here, 9 is a thermal head in which a large number of heating elements 8 are arranged in a line, and 5 is a platen roller that functions to convey the original 1 in the direction of the arrow in the figure while pressing it against the thermal head 9. The platen roller 5 is a rubber roller and is driven to rotate in the direction of the arrow in the figure. Reference numeral 6 is a guide plate for receiving the original plate 1, and 7 is a control device. The heating head 8 of the thermal head 9 selectively generates heat in response to a signal from the control device 7 to apply heat to the surface of the original 1 (from the lipophilic coating 3 side). As a result, in the foaming agent layer 2 of the original plate 1, the foaming agent explodes or thermally decomposes due to the heat of the thermal head 9, the volume increases and a large number of open cells are formed therein. Then, only that portion of the lipophilic coating 3 on the surface is destroyed, and an image portion having ink adhesion is formed there.

FIG. 3 shows the situation in more detail. The original 1 is conveyed so that the side having the lipophilic coating 3 is in contact with the heating element 8 of the thermal head 9. The portion 3a locally foamed by the heating element 8 of the thermal head 9 serves as an image forming portion, and the non-foaming portion 3b.
Is a non-image forming section. In this way, due to the rotation of the platen roller 5 and the heat generation of the heating element 8 of the thermal head 9, only the portion corresponding to the ink transfer portion based on the image information is foamed in the original plate 1 and the lipophilic film is also removed. Only the water-based ink adheres, and since the lipophilic coating 3 exists on the non-foamed portion 3b, the water-based ink does not adhere.

FIG. 4 is a schematic view of a lithographic printing apparatus using the printing plate produced as described above. The lithographic printing plate 1'where the foamed portion 3a is selectively formed by the thermal head 9 (that is, the plate is made) is held by winding the foamed portion 3a on the outer periphery of the plate cylinder 10 with its leading end clamped. It An ink supply roller 11 is provided in the vicinity of the plate cylinder 10. The ink supply roller 11 causes the water-based ink in the ink pan 12 to adhere to the outer circumference thereof and is measured by a blade 13 and then wound around the outer circumference of the plate cylinder 10. It serves to supply the foamed portion 3a of the printed printing plate 1 '. 14
Is a printing paper, and 15 is a press roller. Water-based inks have significantly lower viscosities than conventional offset inks.

The ink supply roller 11 is rotationally driven in the direction of the arrow. Further, the ink supply roller 11 is the plate cylinder 10.
You don't have to press hard against. FIG. 5 is a schematic view showing the ink supply portion. Since the foamed portion 3a of the printing plate 1'absorbs the water-based ink 16 quickly, the ink supply roller 11 may make a light contact with the printing plate 1 '. Since the surface of the non-foamed portion 3b is lipophilic, the water-based ink 16 does not adhere. Aqueous ink is, for example, polyvinyl alcohol 5 having a polymerization degree of about 500 and an oxidation degree of about 80.
It can be prepared by adding 100 g of water to 100 ml of water to swell well and adding 0.01% of eosin paint thereto.

As shown in FIG. 4, the lithographic printing apparatus of the present invention has a simple structure and prints directly on the printing paper 14 conveyed by the paper feed roller 17 without using a blanket as in the conventional offset printing. can do. In this case, since the water-based ink absorbed in the foamed portion 3a of the printing plate 1'is easily transferred to the surface of the printing paper 14, the pressing force of the press roller 15 does not need to be so large.

[0022]

According to the invention of claim 1, the lithographic printing plate precursor can be obtained easily and at low cost. Claim 2
According to the invention, the plate making mechanism can be downsized because the plate can be easily made with a thermal head and the like, and since it can be handled by a digital signal, the signal can be directly transferred to and from another OA device, and the planographic printing plate The plate making can be easily performed. According to the invention of claim 3, the inking system is very simple because only the foaming portion of the printing plate itself has ink absorbency, and a troublesome device for supplying dampening water is unnecessary. In addition, since the printing can be performed without using a blanket, a blanket cleaning mechanism is not required, and the structure of the printing machine becomes very simple. Furthermore,
Since the printing pressure for printing is small, the machine can be made lighter and less noise. In addition, since it is possible to use a water-based ink that has good penetrability into paper, it is safe.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a lithographic printing plate precursor according to the invention.

FIG. 2 is a diagram showing a state where plate making is performed.

FIG. 3 is a diagram for explaining in detail how a printing plate is made by plate making.

FIG. 4 is a diagram showing a state where printing is directly performed on a sheet using the planographic printing plate according to the invention.

FIG. 5 is a diagram showing a state where inking is performed on the planographic printing plate according to the invention.

[Explanation of symbols]

1 lithographic printing original plate (1 'lithographic printing plate) 2 foaming agent layer 3 lipophilic coating (3a foaming part (image forming part), 3b
Non-foaming part (non-image forming part) 4 Base sheet 5 Platen roller 6 Guide plate 7 Control device 8 Heating element 9 Thermal head 10 Plate cylinder 11 Ink supply roller 12 Ink pan 13 Blade 14 Printing paper 15 Press roller 16 Water-based ink 17 Supply Paper roller

Claims (3)

[Claims] 1. A lithographic printing plate precursor comprising a layer in which a foaming agent is dispersed in a polymer material layer, and a lipophilic coating film provided on one surface and a base sheet on the other surface. 2. While transporting the original plate according to claim 1,
A lithographic printing method characterized in that the foaming agent dispersion layer is subjected to an oleophilic film to selectively apply heat energy from a heating element such as a thermal head to locally explode the foaming agent dispersion layer to cause a thermal decomposition reaction to form a foamed portion. How to make a plate. 3. The printing plate obtained in claim 2 is mounted on a plate cylinder so that the foamed part side is the plate surface, and water-based ink is supplied to the surface of the printing plate to selectively adhere the water-based ink to the foamed part. A lithographic printing method comprising obtaining a printed matter by directly contacting a printing paper with the printing plate having the water-based ink adhered thereto.