JPH06250424A - Direct drawing type planographic printing plate material - Google Patents

Abstract

PURPOSE:To obtain a direct drawing type planographic printing material which can produced with a copy machine of an electrostatic transfer system or with a laser printer, has good printing durability without contamination of print, and causes little fog in a non-picture area due to scattering of a toner. CONSTITUTION:A picture image accepting layer containing zinc oxide prepared by a dry method, zinc oxide prepared by a wet method, and a binder is formed on a water-resistant supporting body. The printing material has the saturation electrification voltage of -10V to -200V at an applied voltage of -5kV, and has 10<12>OMEGA.cm to <=10<14>OMEGA.cm volume resistivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct drawing type planographic printing plate material. More specifically, the present invention is a direct drawing type lithographic plate that can be plate-formed by using an electrostatic transfer system such as a xerographic copying machine or a laser printer, and has little stain and fogging stain due to toner scattering. It relates to a printing plate material.

[0002]

2. Description of the Related Art With the recent development of office equipment and the development of office automation, in the field of light printing, a direct drawing type lithographic printing plate can be easily made by an electrostatic transfer type copying machine or a laser printer. The printing method using wood is rapidly spreading. A conventional direct-drawing type lithographic printing plate material is configured by providing an image receiving layer containing a pigment, a water-soluble binder and a water-proofing agent as main components on a support made of paper, plastic film or the like. In such a direct drawing type lithographic printing plate, a method of forming a lipophilic image on the image receiving layer by using a lipophilic ink by a typewriter or handwriting, or formed on an electrophotographic photoreceptor. A toner image is transferred to the image receiving layer of a lithographic printing plate and heat-fixed to form a lipophilic image. In order to print using such a lithographic printing plate, the non-image area may be desensitized with an etching solution, and this may be subjected to lithographic printing as a printing master.

A direct drawing type lithographic printing plate material comprising an image receiving layer comprising an inorganic pigment, a water-soluble binder, a water-proofing agent and the like on a water-resistant support is, for example, JP-B-40-
23581, JP-A-48-9802, JP-A-57-
205196, JP-A-60-2309, JP-A-57.
-1791, JP-A-57-15998, and JP-A-57.
-96900, JP-A-57-205196, JP-A-63-166590, JP-A-63-166591,
JP-A-63-256493, JP-A-63-31738
No. 8 and JP-A-1-114488.

However, the practical use of such a conventional direct drawing type lithographic printing plate material has declined at present. The first reason is that in the electrostatic transfer type plate making, toner is scattered during the transfer of the toner image, causing fog in the non-image area,
In addition, this is because of the drawback that it appears as stains on the printed matter. Further, in JP-A-61-184593, the volume resistivity of a plate material for direct drawing lithographic printing is 10 ¹⁰ Ω · cm to 1
Although it is described that it is specified as 0 ¹³ Ω · cm, it was confirmed that even if the volume resistivity of the plate is within the above range, fogging is often generated due to the scattering of toner, resulting in stains during printing. .

[0005]

SUMMARY OF THE INVENTION The present invention has less print stains, excellent printing durability, and less fog stains in non-image areas due to toner scattering during electrostatic transfer type plate making.
Moreover, it is an object of the present invention to provide a direct drawing type planographic printing plate material having a good toner transfer efficiency to the image area.

[0006]

Means for Solving the Problems The inventors of the present invention have made earnest studies on a plate material for direct drawing type lithographic printing suitable for plate making by an electrostatic transfer system, and as a result, have identified the charging characteristics of the plate for direct drawing type lithographic printing. The present invention has been completed by finding that the above problems can be solved by regulating the content within the above range and limiting the volume resistivity within the specific range.

That is, the direct drawing type planographic printing plate material of the present invention is formed on a water resistant support and the water resistant support,
And containing a zinc oxide pigment and a binder resin,
It has an image receiving layer and has an applied voltage of -5 kV and -20 to 20
It shows a saturated electrification potential of -200 V, and 10 ¹² to 10 ¹⁴
It is characterized by having a volume resistivity of Ω · cm.

[0008]

The direct-drawing type lithographic printing plate material of the present invention shows a saturated charging potential of -10 V to -200 V at an applied voltage of -5 kV and a volume resistivity of 10 ¹² Ω · cm to 10 ¹⁴ Ω · cm. I have. By using the printing plate material of the present invention having the above characteristics, it is possible to suppress fogging due to toner scattering in the plate making process and obtain a plate making product having good toner transfer efficiency. When the saturated charging potential at an applied voltage of -5 kV exceeds -200 V (negative numerical value is larger than 200), the volume resistivity is 10 ¹⁰ Ω · cm 10 ¹²
Even if the value is as low as Ω · cm, there is a lot of fogging due to toner scattering, which appears as stains during printing. Moreover, the saturation charging potential at an applied voltage of -5 kV is -10 V.
If it is less than (negative value is less than 10), toner fogging is reduced, but its volume resistivity is from 10 ¹³ Ω · cm to 1
Even if the value is as high as about 0 ¹⁴ Ω · cm, the printing efficiency of the plate is lowered because the transfer efficiency and the fixing property of the toner are lowered.

In the direct drawing type lithographic printing plate material of the present invention, the zinc oxide contained in the image receiving layer includes zinc oxide produced by a dry method (so-called French zinc oxide) and oxidation produced by a wet method. It is composed of a mixture with zinc (usually called activated zinc white), and the blending amount of each is 55% to 7% of dry process zinc oxide based on the total weight of the image receiving layer.
It is preferable that the wet process zinc oxide is 5% and the wet zinc oxide is 10% to 30%. If the content of the dry process zinc oxide is less than 55% based on the total weight of the image receiving amount, scumming is likely to occur at the time of printing by a plate obtained from the dry process zinc oxide. The saturated charging potential at a voltage of -5 kV exceeds -200 V, which increases toner fog. On the other hand, when the content of the wet process zinc oxide is less than 10%, the saturated charging potential at an applied voltage of -5 kV exceeds -200 V, and therefore toner fogging increases. Further, if it exceeds 30%, scumming is likely to occur during printing with the obtained plate.

The dry weight of the image receiving layer of the plate material for direct drawing lithographic printing according to the present invention is preferably ⁴ to 15 g / m ² . When the weight of the image receiving amount is less than 4 g / m ^{2, the} desensitizing ability of the obtained printing plate material becomes insufficient and printing stains easily occur. Further, when it exceeds 15 g / m ² , the inductive property of the obtained printing plate is excessively increased,
In the electrostatic transfer type plate making, fog due to toner scattering increases.

The binder resin used in the image receiving layer of the lithographic printing plate material of the present invention includes starch, starch derivatives, cellulose derivatives (for example, carboxymethyl cellulose and hydroxymethyl cellulose) polyvinyl alcohol, modified polyvinyl alcohol, casein,
And water-soluble resins such as ammonium acrylate, and water-insoluble and water-dispersible emulsion resins such as acrylic resins, SBR, NBR, and vinyl acetate-ethylene copolymers can be used. The resins may be used alone or in combination of two or more. When only the water-soluble resin is used alone, it is preferable to use an appropriate amount of a water-proofing agent together with it in order to improve the printing durability of the printing plate obtained.

Further, as the binder used in the image receiving layer, solvent-soluble (water-insoluble) resins such as polyester resin, acrylic resin, epoxy resin, polycarbonate resin, and butyral resin can be used. In this case, the coating solution for the image receiving layer can be prepared using a solvent such as toluene.

The content of the binder in the image receiving layer is generally preferably 30% or less based on the total weight of the image receiving layer. If it is 30% or more, desensitization of the non-image area of the obtained printing plate may be insufficient,
Therefore, stains are likely to occur during printing.

As the water-resistant support of the present invention, water-resistant treated paper, plastic film, or the like can be used. When paper is used as the base material, it is preferable to form a water resistant support by providing a water resistant layer on the surface side on which the image receiving layer is provided in order to improve printing durability.

A back coat layer may be provided on the back surface of the support to prevent curling. Further, a solvent resistant layer may be provided between the water resistant layer and the image receiving layer, which makes it possible to provide the image receiving layer using a solvent soluble resin such as an acrylic resin.

The water resistant layer and the back coat layer are generally formed by using an emulsion type resin such as acrylic resin, SBR or NBR. These resins may be used alone or in combination of two or more kinds. Further, an appropriate amount of pigment may be contained in these layers. The coating amount of the water resistant layer and the back coat layer, respectively,
The dry weight is preferably 5 to 10 g / m ² and 5 to ²⁰ g / m ² . When the coating weight of each is less than 5 g / m ² , sufficient water resistance and curl prevention effects may not be obtained.

The solvent-resistant layer is generally made of a solvent-resistant material, for example, a water-soluble resin such as starch, a cellulose derivative, casein or polyvinyl alcohol, and a water-resistant acrylic resin, an emulsion type resin such as SBR or NBR. It is formed of a water-proofing agent and a pigment, and the coating amount thereof is preferably 5 to 10 g / m ² . It is 5
If it is less than g / m ² , the solvent resistance of the obtained plate material is insufficient.

The practically sufficient printing durability required for the direct drawing type planographic printing plate is based on the fact that the number of through printing is at least 500.

[0019]

EXAMPLES The present invention will be described in more detail by way of examples. However, these do not limit the scope of the present invention. In the examples, "parts" and "%" are "parts by weight" and "% by weight", respectively, unless otherwise specified.
Represents

EXAMPLE 1 A substrate made of wet-strengthened and internally sized paper,
A coating solution having the following composition was applied onto the surface of the image-receiving layer so as to have a dry weight of 10 g / m ² , and dried to form a water resistant layer. Image-receiving layer side water-resistant layer forming coating solution composition Ingredient Weight clay dispersion of (50% solids) 30 parts of emulsion type acrylic resin (40% solids, 50 parts trademark: ARON A-104, manufactured by Toagosei Industrial) SBR (solid content 50%, trademark: Nipol LX-415, 40 parts, manufactured by Nippon Zeon) Water 50 parts Cobb size degree of this water resistant layer is determined according to JIS P-8140.
It was 0.5 g / m ² when measured in accordance with.

Next, the back surface of the paper substrate was coated with the following composition.
Dry weight of cloth liquid is 15g / m²So that it becomes
Dry to form a back coat layer to obtain a water resistant support.
It was Composition of coating liquid for forming backcoat layer Component Weight Clay dispersion (50%) 60 parts Emulsion type acrylic resin (solid content 45%, 45 parts Trademark: Bonron S-482, manufactured by Mitsui Toatsu Chemicals) Water 50 parts

Next, a coating solution having the following composition was coated on the water resistant layer of the above support so that the dry weight was 10 g / m ² , and dried to form an image receiving layer. Image receiving layer coating solution composition Ingredient Weight dry method zinc oxide dispersion (50%) 120 parts (Trademark: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) wet method zinc oxide dispersion (50%) 40 parts ( Trademark: Activated zinc flower ZINCA-20, manufactured by Sakai Chemical Industry) Emulsion type acrylic resin (solid content 40%, 50 parts Trademark: Aron A-104, manufactured by Toagosei Chemical Industry Co., Ltd.) Water 40 parts

Test A laser printer (trademark: Canon Laser) was placed on the image-receiving layer of the lithographic printing plate material thus prepared.
The image was printed and made by using Shot B406E). The fogging caused by toner scattering (toner fogging) generated at this time was observed with an optical microscope and the naked eye, and a sensory evaluation was performed. As a result, it was confirmed that the fog in the non-image area due to the toner scattering was extremely small and the plate was good. In order to measure the toner transfer efficiency, the toner adhesion amount (image density) of a solid image portion of 3 cm × 3 cm was measured using a Macbeth reflection densitometer.

In order to test the charging property of the plate, Kawaguchi Electric's EPA S-428 (Electrostatic) was used.
Paper Analyzer) was used to apply a corona voltage of -5 kV to the test plate material, and the saturated charging potential Vs of the test plate was measured. In addition, the volume resistivity of the test plate material is measured by Yokogawa Hewlett-Packard's High Insulation Resistance Meter High Re.
science Meter Model 4329
It measured using A.

This plate was desensitized with a cyan-based etchant manufactured by Itek Co., Ltd., and then printed using an offset printing machine. Sensory evaluation of printing stains was carried out, thin line images were observed, and printing durability was evaluated. . Table 1 shows the evaluation results of the above-mentioned toner fog, toner transfer efficiency (image density), plate charging property, volume resistance, printing stain, and printing durability.

Example 2 A support having a water resistant layer and a back coat layer of Example 1 was used, and a coating solution for a solvent resistant layer having the following composition was dried on the water resistant layer to a dry weight of 7 g / m ² . So that it becomes 5
It was cured at 0 ° C. for 72 hours to form a solvent resistant layer. Solvent layer forming coating solution composition Ingredient Weight clay dispersion (50%) 25 parts 20 parts casein 10% aqueous solution of 100 parts of an emulsion type acrylic resin (trademark: ARON A-104) Glyoxal 5 parts Water 25 parts

Next, the following compositions were prepared and dispersed by a sand grinder to prepare a solvent dispersion type image-receiving layer forming coating solution, which was coated so that the dry weight was 10 g / m ^2. Then, an image receiving layer was formed. Composition Ingredient Weight dry method zinc oxide 65 parts of the image receiving layer coating liquid (trademark: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) wet method zinc oxide 20 parts (Trademark: activated zinc white ZINCA-20, manufactured by Sakai Chemical Industry Made) Acrylic resin 30 parts (Trademark: Acridic A-405, solid content: 50% by weight, manufactured by Dainippon Ink and Chemicals, Inc.) Toluene 85 parts

The lithographic printing plate thus obtained was tested and evaluated in the same manner as in Example 1. As a result, it was confirmed that the obtained plate-making product had less toner fog and was good.
The test results are shown in Table 1.

Comparative Example 1 In the same manner as in Example 2, a water resistant layer, a back coat layer and a solvent resistant layer having the following compositions were formed on a paper substrate. That is, by adding a conductive agent to the water resistant layer and the back coat layer,
The volume resistivity of the obtained plate is 10 ¹⁰ Ω · cm to 10 ¹² Ω ·
It was adjusted to about cm, and only zinc oxide of the dry method (French method) was used as the pigment of the image receiving layer.

A coating solution having the following composition was coated on the surface of the image receiving layer side of a substrate made of paper which had been wet-strengthened and internally sized to a dry weight of 10 g / m ² and dried. , A water resistant layer was formed. Image-receiving layer side water-resistant layer forming coating solution composition Ingredient Weight clay dispersion of (50% solids) 30 parts of emulsion type acrylic resin (40% solids, 50 parts trademark: ARON A-104, manufactured by Toagosei Industrial) SBR (solid content 50%, trademark: Nipol LX-415, 40 parts made by Zeon Corporation) Anionic polymer conductive agent (30% aqueous solution, 10 parts Trademark: Chemistat 6120, Sanyo Kasei) Water 43 parts This water resistance The degree of Cobb size of the elastic layer is determined according to JIS P-8140.
It was 0.5 g / m ² when measured in accordance with.

Next, a back coating layer was formed by coating the back surface of the paper substrate with a coating solution having the following composition so that the dry weight was 15 g / m ² and drying. Backcoat coating composition was Composition Ingredient Weight clay dispersion (50%) 60 parts emulsion type acrylic resin (45% solids, 45 parts trademark Bonron S-482, manufactured by Mitsui Toatsu Chemicals) Anionic High Molecular conductive agent (30% aqueous solution, 15 parts Trademark: Chemistat 6120, Sanyo Kasei) Water 40 parts

Next, a coating solution for a solvent resistant layer having the following composition was applied onto the above water resistant layer so that the dry weight was 7 g / m ² , and this was cured at 50 ° C. for 72 hours. Thus, a solvent resistant layer was formed to obtain a support. Solvent layer forming coating solution composition Ingredient Weight clay dispersion (50%) 25 parts 20 parts casein 10% aqueous solution of 100 parts of an emulsion type acrylic resin (trademark: ARON A-104) Glyoxal 5 parts Water 25 parts

Next, the following compositions were prepared and dispersed by a sand grinder to prepare a solvent dispersion type coating solution for forming an image receiving layer, which was dried on the solvent resistant layer of the support. Of 10 g / m ² was applied to form an image receiving layer to obtain a printing plate material. Composition Ingredient Weight dry method zinc oxide 85 parts of the image receiving layer coating liquid (trademark: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) 30 parts Acrylic resin (Trademark: ACRYDIC A-405, solid content: 50 % By weight, manufactured by Dainippon Ink and Chemicals, Inc.) Toluene 85 parts The obtained lithographic printing plate was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 A lithographic printing plate material was prepared in the same manner as in Comparative Example 1. However, a coating solution having the following composition was coated on the solvent-resistant layer of the support so that the dry weight was 10 g / m ² , and dried to form an image receiving layer. Composition Ingredient Weight dry method zinc oxide 65 parts of the image receiving layer coating liquid (trademark: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) wet method zinc oxide 20 parts (Trademark: activated zinc white ZINCA-20, manufactured by Sakai Chemical Industry Acrylic resin 30 parts (Trademark: Acridic A-405, solid content: 50% by weight, manufactured by Dainippon Ink and Chemicals, Inc.) Toluene 85 parts The obtained lithographic printing plate was tested in the same manner as in Example 1. And evaluated. The results are shown in Table 1.

Comparative Example 3 A lithographic printing plate material was prepared in the same manner as in Example 2. However,
No wet process zinc oxide was used in the image receiving layer. That is, a coating solution having the following composition was coated on the solvent resistant layer of the support so that the dry weight was 10 g / m ² , and dried to form an image receiving layer. Composition Ingredient Weight dry method zinc oxide 85 parts of the image receiving layer coating liquid (trademark: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) 30 parts Acrylic resin (Trademark: ACRYDIC A-405, solid content: 50 % By weight, manufactured by Dainippon Ink and Chemicals, Inc.) Toluene 85 parts The obtained lithographic printing plate was tested and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0036]

[Table 1]

[0037]

EFFECTS OF THE INVENTION The direct drawing type planographic printing plate material of the present invention is more susceptible to toner scattering than conventional direct drawing type planographic printing plate materials when plate-making by an electrostatic transfer type copying machine or laser printer. Fogging in the non-image area is significantly reduced, stains during printing are extremely small, and printing durability is excellent. Therefore, the direct drawing type planographic printing plate material of the present invention,
Since plate making can be easily performed using an electrostatic transfer type copying machine, a laser printer, etc., it can be advantageously used in the fields of office printing and light printing.

Claims (1)

[Claims] 1. A water-resistant support, and an image-receiving layer formed on the water-resistant support and containing a zinc oxide pigment and a binder resin. The applied voltage is -5 V to -10 V to -200 V. The saturated charging potential of 10 and
A direct-drawing type planographic printing plate material having a volume resistivity of ¹² to 10 ¹⁴ Ω · cm.