JPH04299359A - Base material for electrophotographic planographic printing original plate - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic type planographic printing original plate having excellent electrophotographic characteristics and printing resistance by using metallic foil laminated by using an adhesive which is mixed with a cold setting type polyurethane resin and a carbon black and has a high electrical conductivity as the base material. CONSTITUTION:The adhesive for the metallic foil and paper at the time of forming the metal foil-laminated paper is a mixture composed of the cold setting type polyurethane resin having the high electrical conductivity of <=1X10<14>OMEGAcm volumetric resistance value and carbon black. Then, the electrophotographic planographic printing original plate which does not fog in spite of execution of plate making under a low humidity condition and has the good printing resistance is obtd. when the metal foil-laminated paper laminated by using the adhesive formed by mixing the cold setting type polyurethane resin and the carbon black and having the high electrical conductivity is used as the base material.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has no fog during plate making,
The present invention relates to a method for producing a base material for an electrophotographic lithographic printing plate having excellent electrophotographic properties and printing durability with little plate elongation during printing.

0002

2. Description of the Related Art Generally, electrophotographic printing original plates are constructed by providing a layer containing an inorganic or organic optical semiconductor on a base material having characteristics such as electrical conductivity and water resistance. Sheet-like materials such as paper, metal foil, film, or composites of these are used as the base material, but when paper is used, it is usually treated with water-resistance treatment to improve the quality of the electrophotographic image. A coating layer containing an inorganic electrolyte such as sodium chloride, potassium chloride, calcium chloride, or an organic polymer electrolyte such as a quaternary ammonium salt, which is called a conductive agent, is provided.

However, when a lithographic printing original plate is prepared using paper that has been subjected to such treatment as a base material, plate elongation is unavoidable due to the application of dampening water during printing, even though the paper has been subjected to water-resistant treatment. This causes problems such as wrinkles on the plate during printing, misregistration of printed matter, and irregularly sized ruled lines.

[0004] Instead of paper, it is possible to improve wet elongation and tensile strength by using paper made of metal foils such as aluminum, zinc, copper, etc. bonded with adhesive (hereinafter referred to as metal foil laminated paper). A printing original plate with good dimensional stability can be obtained (for example, Japanese Patent Publication No. 38-17
No. 249, No. 41-2426, No. 41-12432, etc.).

[0005] Metal foil laminated paper is usually made by bonding one or both sides of metal foil to paper using an adhesive. Generally, vinyl acetate resin, acrylic resin, polyolefin resin, polyurethane resin, etc. are used.

[0006] These are applied as a water-based paint in the form of an emulsion or as a solvent-based paint by selecting an appropriate solvent between the layers of metal foil and paper, and then laminated.

[0007] Water-soluble resins such as casein, poval, and starch are also used as adhesives.

[0008] Other lamination methods include hot-melt methods using resins that melt when heated, such as wax resins, polyolefin resins (polyethylene, polypropylene, ethylene-vinyl acetate copolymer resins, ionomers, etc.), and extrusion coating. The law is also often put into practice.

The present inventors manufactured an electrophotographic printing original plate using metal foil laminated paper as a base material and investigated its practicality.The main physical properties required for the adhesive between the metal foil and the paper were as follows. These are the following three points.

(1) During plate making, when the developer is heat-fixed, blisters (interlayer destruction, also called blisters) do not occur due to softening of the adhesive or insufficient adhesive strength.

(2) During printing, it should not be destroyed by soaking water that enters from the edge of the printing original plate. That is, the adhesive layer is dissolved or swelled by the dampening water and the adhesive strength is reduced, so that the paper and the metal foil do not separate during printing and the printing original plate is destroyed.

(3) During plate making, fogging (a phenomenon in which toner adheres to non-image areas) due to a decrease in conductivity does not occur, especially under low humidity conditions.

[0013] For example, metal foil laminated paper produced by the hot melt method or extrusion coating method is completely unsuitable in respect of the above point (1). However, the above problem (1) can be almost solved by taking measures such as reducing the coating thickness in the back layer or applying a mixture of breathable substances.

Points (1) and (2) can be improved to some extent by using a mixture of an acrylic resin emulsion and a synthetic rubber resin or a synthetic resin aqueous emulsion and casein at a certain ratio as the adhesive between metal foil and paper. has already been reported (Japanese Unexamined Patent Publication No. 58-16892,
-17449).

Regarding point (3), when plate making is performed under low humidity conditions, the moisture content of the base material decreases and the conductivity decreases, causing non-image areas where the charge would normally disappear upon exposure to light. It is known that fogging is more likely to occur because charges remain on the surface. In order to prevent fogging, there is a method of adding inorganic electrolytes such as sodium chloride, potassium chloride, calcium chloride, or organic polymer electrolytes such as quaternary ammonium salts to the paper layer, but it is When an electrophotographic printing original plate is produced as a material, the current situation is that even if this method is used, it is not possible to completely prevent the occurrence of fogging during plate making under low humidity conditions.

[0016]

[Problems to be Solved by the Invention] The present invention uses metal foil laminated paper as a base material, which has excellent electrophotographic properties that do not cause fogging even when plate-making is performed under low humidity conditions, which could not be achieved using conventional techniques. The purpose of the present invention is to provide a base material for an electrophotographic lithographic printing original plate that has good printing durability and is used as a base material for electrophotographic lithography.

[0017]

[Means for Solving the Problems] The present inventors investigated the relationship between the characteristics of the adhesive between metal foil and paper and fog during plate making, and found that It has become clear that there is a close relationship between fogging. In other words, when an adhesive with low conductivity is used, the conductivity of the base material decreases significantly under low humidity conditions, causing fogging during plate making, but when an adhesive with high conductivity is used, the conductivity of the base material decreases significantly even under low humidity conditions. It was found that there was little decrease in the conductivity of the material and no fogging occurred during plate making. Therefore, by increasing the conductivity of the adhesive by mixing a conductive substance into the adhesive, it is possible to create a base material for electrophotographic lithographic printing plates with excellent electrophotographic properties that do not cause fogging even when plate making is performed under low humidity conditions. It has been found that this can be obtained, and the present invention has been achieved.

The metal foil used in the present invention serves as a conductive layer necessary for creating an image by electrophotography and a support that prevents elongation and decrease in tensile strength when dampening water during printing soaks into the paper layer. It has the dual role of a layer, and any material may be used as long as it is a thin metal film that meets this purpose. For example, it is a single composition of iron, copper, tin, aluminum, lead, zinc, etc., or an alloy thereof. Among these, aluminum is preferred as a material to be laminated to paper because it has a low specific gravity, is light, has good spreadability, and is easy to process into foil, but the present invention is of course limited to this. It's not a thing.

In the present invention, the highly conductive adhesive used between metal foil and paper refers to one with a volume resistivity of 1×10 14 Ωcm or less;
If it is larger than cm, fogging is unavoidable when plate making is performed under low humidity conditions of about 10% RH.

[0020] In the present invention, the dry lamination method is preferable to the glue lamination method for adhering the metal foil and paper because it has much better water resistance and heat resistance. In addition, in the dry lamination method, heating aging is generally performed to speed up the rise of adhesion, but during this time, oxidation of the metal foil surface and attachment of organic substances occur, making it necessary to create an intermediate layer between the base material and the image-receiving layer. When laminating paper on both sides of the metal foil, the adhesion between the metal foil and the intermediate layer decreases, or when laminating paper on both sides of the metal foil, the adhesiveness between the metal foil and the paper decreases during the second lamination, so heating aging is not necessary. It is preferable to use a room temperature curable polyurethane resin as the adhesive.

[0021] The room temperature curing polyurethane resin used in the present invention has a polyurethane structure in which the final reaction-cured coating film has one or more urethane groups in one molecule, and does not require heating for curing. It is something. These adhesives include one-component adhesives that use a resin with an isocyanate group at the end, and two-component adhesives that use a combination of a base agent made of a resin with a hydroxyl group at the end and a curing agent made of a compound with an isocyanate group at the end. Although it is classified as a liquid adhesive, in the present invention, similar effects can be obtained by using either a one-component adhesive or a two-component adhesive.

[0022] In the present invention, the conductive substance mixed in order to increase the conductivity of the adhesive includes French Patent No. 22771.
Metals such as zinc, magnesium, tin, barium, indium, molybdenum, aluminum, titanium, silicon, and their oxides or carbon black as described in each specification of No. 36 and U.S. Patent No. 3,597,272 are included. However, carbon black is advantageous because it is relatively inexpensive and easy to handle.

[0023] The blending ratio of room temperature curable polyurethane resin and carbon black is 200:1 to 10 in dry weight ratio.
:1 range is preferable, and if the blending ratio of carbon black is lower than this range, the necessary conductivity cannot be obtained,
If the blending ratio is higher than this range, the adhesive strength will decrease.

[0024] Gravure coaters, roll coaters, rod coaters, die coaters, curtain coaters, blade coaters, etc. can be used to apply the adhesive, but gravure coaters and reverse roll coaters are preferred from the viewpoint of coating liquid viscosity and application amount. is preferred.

The surface to which the adhesive is applied may be either metal foil or paper, but if the metal foil is thin, the paper surface may be used to prevent wrinkles from forming on the metal foil due to shrinkage of the adhesive when drying. It is preferable to apply an adhesive, and if the paper surface is not treated with solvent resistance, it is recommended to apply an adhesive to the metal foil surface to prevent the adhesive from penetrating into the paper layer along with the solvent. is preferred.

If the amount of adhesive applied is extremely small, sufficient adhesion between the metal foil and paper cannot be obtained. In particular, because one side of the laminated paper is paper, and the surface has many microscopic irregularities, and it is inevitable that some of the adhesive will penetrate into the paper layer, a coating amount of at least 1 g/m2 is required. is necessary. If the coating amount is less than this, the coating surface will not be covered sufficiently with the adhesive, and the adhesive strength between the metal foil and the paper will partially decrease. When the plate is heated to high temperatures during plate making, it cannot withstand the generation of water vapor from within the paper layer and the expansion of air, and blisters occur between the metal foil and the paper. The upper limit of the coating amount depends on the performance of the laminator, the surface properties of the paper,
Alternatively, it is naturally constrained by economic considerations. Practically, 1
A range of ~10 g/m2 is preferred.

In the present invention, the intermediate layer usually contains a synthetic resin emulsion, and if necessary, pigments such as clay, sericite, and calcium carbonate, water-soluble adhesives such as starch and polyvinyl alcohol, conductive agents, waterproofing agents, etc. It is mixed with and applied.

In the present invention, the image-receiving layer refers to a layer formed by electrophotography, and contains a photosemiconductor as a basic component. Usually, an inorganic optical semiconductor such as zinc oxide, titanium dioxide, or cadmium sulfide dispersed in an insulating adhesive resin, or an organic optical semiconductor such as polyvinyl carbazole is used.

In the present invention, a backing layer may be provided on the opposite side of the substrate from the image-receiving layer in order to improve the water resistance and conductivity of the substrate, and such a backing layer usually contains a synthetic resin emulsion. However, if necessary, it is mixed with pigments such as clay, sericite, and calcium carbonate, water-soluble adhesives such as starch and polyvinyl alcohol, conductive agents, waterproofing agents, etc., and then applied.

[0030]

[Function] In the present invention, if metal foil laminated paper is used as a base material using a highly conductive adhesive to bond metal foil and paper, the conductivity of the base material will decrease less even under low humidity conditions, making it easier for plate making. An electrophotographic lithographic printing original plate with excellent electrophotographic properties that does not sometimes cause fogging can be obtained.

[0031]

EXAMPLES Next, the present invention will be explained in more detail with reference to examples. Note that all parts and percentages shown below are based on weight.

Example 1 An adhesive having the following composition was prepared by mixing a room temperature curable polyurethane resin and carbon black at a dry weight ratio of 47.9:1, and the dry coating amount was applied to a 50 μm thick aluminum foil. Coat to a concentration of 3.0 g/m2, air dry, and then dry at 20°C for 6
Hewlett-Packard 160 under conditions of 5% RH.
The volume resistance was measured using a 08A type resistivity cell and was found to be 3.7×10 10 Ωcm. (Composition 1) Polyester polyol resin (BLS-PC
21, manufactured by Toyo Morton, solid content 35%): 15 parts Polyisocyanate (CAT-100, manufactured by Toyo Morton, solid content 50%): 1 part Carbon black (20% ethyl acetate dispersion): 0.6
Part ethyl acetate: 3 parts

[0033] This adhesive was applied to one side of a 10 μm thick aluminum foil so that the dry coating amount was 3.0 g/m2.
Commercially available high-quality paper with a basis weight of 50 g/m2 was laminated. This aluminum foil laminated paper was left at room temperature for 2 days to perform room temperature aging, and then an adhesive with the above composition was applied to the other aluminum foil surface so that the dry coating amount was 3.0 g/m2. Laminated with high quality paper. This aluminum foil laminated paper was left at room temperature for 2 days to perform room temperature aging.

Next, an intermediate layer having the composition shown below was coated on one side of the aluminum foil laminated paper so that the dry coating amount was 10 g/m 2 and dried. Sericite-containing inorganic pigment (Zeeklite TMC, manufactured by Zeeklite Chemical, 50% aqueous dispersion): 100 parts Carboxyl-modified SBR latex (solid content 48%): 50 parts Melamine resin initial condensate (Sumirates Resin-613,
Manufactured by Sumitomo Chemical, solid content 80%): 4 parts organic amine salt catalyst (Sumitex Accelerator A
CX-P, manufactured by Sumitomo Chemical, solid content 35%): 0.4 parts Ammonium polystyrene sulfonate (solid content 30%): 4
Department

Furthermore, on the side opposite to the intermediate layer of this aluminum foil laminated paper, a backing layer having the following composition was applied in a dry coating amount of 15 g/
It was coated to a thickness of m2 and dried. Kaolin (Hydrasperse, made by Huber, 50% aqueous dispersion): 100 parts Sericite-containing inorganic pigment (Zieclite TMC, made by Zeeklite Chemical, 50% aqueous dispersion): 100 parts Oxidized starch (
10% aqueous solution): 60 parts Carboxyl-modified SBR latex (solid content 48%):
150 parts ammonium polystyrene sulfonate (solid content 30%)
: 6 parts melamine resin initial condensate (Sumirates Resin-613,
Manufactured by Sumitomo Chemical, solid content 80%): 4 parts

Next, the dry coating amount on the surface of the intermediate layer is 20 g/m.
A photoconductive layer having the following composition was formed so as to have the following composition. Zinc oxide for electrophotography: 200 parts Acrylic resin (50% liquid): 80 parts Rose Bengal (2% methanol solution): 15 parts It had a surface quality.

[0037] This electrophotographic printing original plate was heated at 20°C for 1
It was seasoned under 0% RH conditions and plate-made using an electrophotographic plate-making machine Diafax EP-31V (manufactured by Mitsubishi Paper Industries, Ltd., a plate-making machine for liquid development).

Next, it was desensitized using an etchant Diafax LOM-OHII (manufactured by Mitsubishi Paper Mills) for electrophotographic offset masters, and then used with an offset printing machine Toko Model.
810 (manufactured by Tokyo Aircraft Instruments).

Even under a low humidity condition of 10% RH, no fogging occurred during plate making, and a clear image with high sensitivity was obtained. Even after treatment with the etchant, there is no curling, and installation into the printing machine is possible with smooth operation. Even after printing more than 10,000 sheets with dampening water, the plate does not stretch or the photosensitive layer peels off. It was confirmed that the printing plate obtained by the present invention was extremely excellent.

Example 2 The adhesive of Example 1 was applied to one side of aluminum foil with a thickness of 10 μm so that the dry coating amount was 3.0 g/m2, and a commercially available high-quality paper with a basis weight of 100 g/m2 was laminated. did. This aluminum foil laminated paper was left at room temperature for 2 days to perform room temperature aging.

Next, an intermediate layer having the following composition was applied to the aluminum foil side of the aluminum foil laminated paper so that the dry coating amount was 10 g/m 2 and dried. Sericite-containing inorganic pigment (Zeeklite TMC, manufactured by Zeeklite Chemical, 50% aqueous dispersion): 100 parts Carboxyl-modified SBR latex (solid content 48%): 100 parts Oxidized starch (solid content 25%): 20 parts Melamine resin Initial condensate (Sumirates Resin-613,
Manufactured by Sumitomo Chemical, solid content 80%): 4 parts organic amine salt catalyst (Sumitex Accelerator A
CX-P, manufactured by Sumitomo Chemical, solid content 35%): 0.4 part

0
[042] Further, on the side opposite to the intermediate layer of this aluminum foil laminated paper, the backing layer of Example 1 was applied in a dry coating amount of 15 g/m2.
Apply it and let it dry.

Next, the dry coating amount on the surface of the intermediate layer was 20 g/m.
Example 1 The photoconductive layer of Example 1 was formed so that the photoconductive layer became 2.
A printed version was created in the same way.

Example 3 An adhesive having the following composition was prepared by mixing a room temperature curing polyurethane resin and carbon black at a dry weight ratio of 153.8:1, and the dry coating amount was applied to a 50 μm thick aluminum foil. Apply to 3.0g/m2, air dry at 20℃,
Hewlett-Packard 16 under conditions of 65% RH
The volume resistance was measured using a 008A type resistivity cell and was found to be 4.6×10 13 Ωcm. (Composition 2) Polyester polyol resin (Takelac A
606, manufactured by Takeda Pharmaceutical, solid content 60%): 9 parts Aromatic isocyanate (Takenate A12, manufactured by Takeda Pharmaceutical, solid content 75%): 1 part Carbon black (ethyl acetate dispersion, solid content 20%)
: 0.2 parts Ethyl acetate: 9 parts

A printing plate was prepared in the same manner as in Example 1 except that the adhesive used in Example 1 was changed to the one described above and the dry coating amount was 3.0 g/m 2 .

Comparative Example 1 An adhesive having the following composition was prepared by mixing a room temperature curable polyurethane resin and carbon black at a dry weight ratio of 287.5:1, and the dry coating amount was applied to a 50 μm thick aluminum foil. Apply to 3.0g/m2, air dry at 20℃,
Hewlett-Packard 16 under conditions of 65% RH
The volume resistivity was measured using a 008A type resistivity cell and was found to be 2.9×10 14 Ωcm. (Composition 3) Polyester polyol resin (BLS-PC
21, manufactured by Toyo Morton, solid content 35%): 15 parts Polyisocyanate (CAT-100, manufactured by Toyo Morton, solid content 50%): 1 part Carbon black (20% ethyl acetate dispersion): 0.1
Part ethyl acetate: 3 parts

A printing plate was prepared in the same manner as in Example 1 except that the adhesive used in Example 1 was changed to the one described above and the dry coating amount was 3.0 g/m 2 .

Comparative Example 2 An adhesive having the following composition was prepared by mixing a room temperature curable polyurethane resin and carbon black at a dry weight ratio of 5:1, and was coated on aluminum foil with a thickness of 50 μm with a dry coating amount of 3.5 μm. 0
g/m2, and after air drying, 20℃, 65%R.
Hewlett-Packard 16008A under H conditions
When the volume resistance is measured using a type resistivity cell, it is 8.
．． It was 5×10 7 Ωcm. (Composition 4) Polyester polyol resin (BLS-PC
21, manufactured by Toyo Morton, solid content 35%): 15 parts Polyisocyanate (CAT-100, manufactured by Toyo Morton, solid content 50%): 1 part Carbon black (20% ethyl acetate dispersion): 1.1
5 parts Ethyl acetate: 3 parts

A printing plate was prepared in the same manner as in Example 1 except that the adhesive used in Example 1 was changed to the one described above and the dry coating amount was 3.0 g/m 2 .

Comparative Example 3 An adhesive having the following composition was prepared by mixing an aqueous acrylic acid ester resin emulsion and carbon black at a dry weight ratio of 100:1, and was coated on aluminum foil with a thickness of 50 μm with a dry coating amount of 3.5 μm. Apply to 0g/m2, and after air drying 2
The volume resistivity was measured at 0° C. and 65% RH using a Hewlett-Packard model 16008A resistivity cell and found to be 5.4×10 9 Ωcm. (Composition 5) Acrylic acid ester resin aqueous emulsion (
Movinyl 987, Hoechst Synthesis, solid content 45%): 1
00 parts Carbon black (10% aqueous dispersion): 4.5 parts

00
51] The adhesive in Example 1 was changed to the one described above,
A printing plate was prepared in the same manner as in Example 1 with a dry coating amount of 3.0 g/m2.

Comparative Example 4 The dry coating amount of the adhesive in Example 1 was changed to 0.8 g/m2.
A printed version was created in the same way.

The evaluation results are summarized in Table 1. Adhesion in the table was evaluated by tape peeling method. In addition, the blister during plate making changes depending on the preheating state of the plate making machine heater section or the heater temperature adjustment scale, so the heater section should be cooled to the same temperature as room temperature, and the heater temperature adjustment scale should be set exactly between the upper and lower limits. The plate was made and judged under these conditions.

[0054]

[Table 1]

[0055]

Effects of the Invention As is clear from the above explanation, according to the present invention, a durable metal foil laminated paper is used as a base material, which has excellent electrophotographic properties and does not cause fogging even when plate-making is performed under low humidity conditions. A base material for an electrophotographic lithographic printing plate having good printability can be obtained.

Claims (3)

[Claims] 1. A base material is a metal foil laminated paper created by bonding one or both sides of a metal foil to paper using an adhesive, and a photoconductive material is applied directly onto the metal foil laminated paper or through an intermediate layer. 1. A base material for an electrophotographic lithographic printing original plate comprising an image-receiving layer containing a substance, wherein the adhesive has a volume resistivity of 1×10 14 Ωcm or less. 2. The adhesive comprises a room temperature curing polyurethane resin and carbon black in a dry weight ratio of 200:1.
2. The base material for an electrophotographic printing original plate according to claim 1, wherein the base material is a mixture in a ratio of 10:1 to 10:1. 3. The base material for an electrophotographic printing original plate according to claim 1 or 2, wherein the adhesive is applied at a rate of 1 g/m 2 or more.