JP2002307853A - Supporting body for electrophotographic lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supporting body for an electrophotographic lithographic printing plate wherein a conductive intermediate layer is hard to be damaged when a photo-sensitive layer is applied on the surface of the supporting body for the electrophotographic lithographic printing plate, wherein the conductive intermediate layer is formed on a sheet-form base material, and in addition, sufficient performances are provided in the plate-making image property, the printing durability or the like of the obtained plate. SOLUTION: The conductive intermediate layer is formed by applying a paint containing a conductive agent and a binder resin on the surface of the sheet-form base material. In addition, a lubricant layer is formed by applying a lubricant on the surface of the conductive intermediate layer. The particle of a polyethylene is preferably used as the lubricant.

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 support used for a lithographic printing plate capable of making a plate by an electrophotographic method. More specifically, the conductive intermediate layer on the support surface is not damaged by abrasion when the photosensitive layer is coated on the support, and has excellent solvent resistance, water resistance, and adhesion to the photosensitive layer. The present invention relates to a support for an electrophotographic lithographic printing plate having an excellent conductive intermediate layer.

[0002]

2. Description of the Related Art Heretofore, as a highly sensitive lithographic printing plate utilizing an electrophotographic system, a photosensitive material coated with a zinc oxide-binder resin-dispersed photoreceptor has been applied to a sheet-like substrate which has been subjected to water and solvent resistance processing. There is a zinc oxide lithographic printing plate having a layer formed thereon.

[0003] Further, a conductive intermediate layer is formed on a sheet-like substrate to form a support for a lithographic printing plate, and a photosensitive layer is formed on the conductive intermediate layer on the surface of the support, so that plate making fog and the like can be prevented. It is also known that a zinc oxide lithographic printing plate having reduced humidity dependency can be obtained.

[0004]

SUMMARY OF THE INVENTION On a conductive intermediate layer of a lithographic printing plate support having a conductive intermediate layer formed on a sheet-like substrate, a zinc oxide-binder resin dispersion-based photoreceptor paint is applied. When forming a lithographic printing plate by forming a photosensitive layer by
The photoreceptor paint is applied using a bar coater or the like. Since the photoreceptor paint is an organic solvent-based paint, the paint remaining at the end of the paint container is liable to become a solid content by volatilization of the organic solvent, and such a solid content may be mixed into the paint. Further, zinc oxide is difficult to disperse in an organic solvent, and aggregates due to poor dispersion may be mixed into the coating material. In the case where the photoreceptor paint mixed with such solids and agglomerates is applied to the surface of the conductive intermediate layer, there arises a problem that the conductive intermediate layer is scratched such as a scratch.

When the conductive intermediate layer is damaged, the conductive intermediate layer is peeled off, the conductivity of the peeled portion is lost, and a charge is not charged, and a white spot phenomenon occurs in which an image cannot be obtained during plate making. In addition, when the scratches occur over several lines, many troubles such as a fogging phenomenon in which the charged toner does not come off during plate-making and the toner gets on may occur.

[0006] In order to prevent the conductive intermediate layer from being damaged during the coating of the photoreceptor paint, the conductive intermediate layer is hardened by adding a cross-linking agent such as melamine resin to prevent the damage. Although a method is conceivable, a sufficient effect is not always obtained.

The problem to be solved by the present invention is that, when a photosensitive layer is coated on a support having a conductive intermediate layer formed on a sheet-like substrate, the conductive intermediate layer is hardly damaged.
An object of the present invention is to provide a support for an electrophotographic lithographic printing plate having a sufficient performance in terms of plate image quality, printing durability and the like of the obtained plate.

[0008]

Means for Solving the Problems The present inventors have conducted various studies with the aim of solving the above-mentioned problems, and as a result, have applied a small amount of a lubricant to the conductive intermediate layer formed on the surface of the support. By doing so, the conductive intermediate layer is hardly damaged when the photosensitive layer is coated on the conductive intermediate layer, and the obtained plate has electrical properties such as fogging during plate making, plate making image quality, and printing. It has been found that the present invention has no adverse effect on printing durability and the like at the time, and the present invention has been completed.

That is, the support for an electrophotographic lithographic printing plate of the present invention forms a conductive intermediate layer by applying a paint containing a conductive agent and a binder resin on the surface of a sheet-like base material. A lubricant layer is formed by further applying a lubricant to the surface of the substrate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to prevent the conductive intermediate layer from being damaged when a photosensitive layer is coated on the conductive intermediate layer on a lithographic printing plate support, the surface of the conductive intermediate layer is protected. As the lubricant to be applied to, polystyrene particles, polyethylene particles, fluororesin particles, fine glass beads, silicon powder,
Examples include fine particles having high hardness such as fine carbon particles, higher fatty acid salts such as calcium stearate and ammonium stearate, and paraffin wax.

In the case of highly fine particles, these particles are present on the surface of the conductive intermediate layer, and in the case of higher fatty acid salts or waxes, the surface of the conductive intermediate layer is made of these substances. , The scratch resistance of the surface of the conductive intermediate layer can be improved.

[0012] When such a lubricant layer is formed on the surface of the conductive intermediate layer, it is necessary to prevent adverse effects during plate making and printing, and to improve the adhesion between the substrate and the conductive intermediate layer. It is necessary to appropriately select the type of the lubricant so as not to adversely affect the conductivity of the conductive intermediate layer and the adhesion between the conductive intermediate layer and the photosensitive layer.

The lubricant exemplified above is applied to the surface of the conductive intermediate layer.
Coating does not have the above-mentioned adverse effects
However, the most effective lubricant for scratch resistance is po
Particles of ethylene. Polyethylene particles
The diameter is preferably 0.1 to 5.0 μm. Particle size is 0.
If it is smaller than 1 μm, particles
Does not provide a reliable effect on scratch resistance
Sometimes. If it is larger than 5.0 μm,
Due to the large diameter, a sufficient effect on scratch resistance can be obtained.
But the surface unevenness increases, affecting plate making image quality.
Is concerned. Coating amount of polyethylene particles
Is 0.1 to 0.5 g / m on a solid content weight basis. ^TwoRange of
preferable. 0.1 g / m coating amount^TwoLess, conductive
The abundance of particles on the surface of the conductive intermediate layer
Sufficient effects may not be obtained in some cases. 0.
5g / m^TwoIf more, the abrasion resistance does not change, but the particle
Presence of the conductive layer impairs the conductivity of the conductive intermediate layer,
It is feared that it will affect the image.

On the other hand, when a higher fatty acid salt or wax is used as a lubricant, the coating amount is 0.1 to 1.0 g / m ^2.
Is preferable. If the coating amount is in this range, the rub resistance is good, and the adhesion between the conductive intermediate layer and the photosensitive layer is not adversely affected.

In applying the lubricant to the conductive intermediate layer,
A gravure coater, bar coater, air knife coater, spray and the like can be applied.

Examples of the conductive agent contained in the conductive intermediate layer include polymer conductive agents such as polyethylene glycol and quaternary ammonium, inorganic conductive agents such as carbon, metal and metal oxide, polypyrrole, polyaniline and polythiophene. Is generally used, but polypyrrole and its derivatives which exhibit a low electric resistance value at a low coating amount and a small particle size can be preferably used.

As the sheet-like substrate used in the present invention, paper, plastic film, or a composite thereof can be selected. Examples of the plastic include polyester, polyethylene, polypropylene, polystyrene, polyvinyl chloride, nylon, and the like. Plastics that can be made into sheets can be appropriately selected.

As a coating material used for the photosensitive layer applied on the conductive intermediate layer via a lubricant layer, zinc oxide as a photoconductive agent, an acrylic resin as a binder, and a cyanine dye as a sensitizer are mixed. Those dispersed by an ordinary method can be preferably used, and the coating amount is preferably 10 to 30 g / m ² .

In general, a lithographic printing plate support has a structure in which a conductive intermediate layer is provided on the surface of a sheet-like substrate and a conductive layer is provided on the back surface, and the front and back surfaces are electrically connected by the conductive layer on the end surfaces (side surfaces). ing. By forming a photosensitive layer on the conductive intermediate layer on the surface of such a support, a lithographic printing plate can be obtained. The conductive layer is made of conductive carbon black, tin oxide, zinc oxide,
Coating a paint mixed with a binder resin such as a conductive metal oxide such as conductive metal oxides such as titanium oxide coated with zinc oxide or antimony oxide, and a conductive polymer such as polythiophene with a low humidity dependency. Can be formed. Alternatively, it may be formed by directly evaporating a metal such as aluminum, gold, silver or the like on the back surface of the sheet-shaped substrate. In any case, the surface resistance of the conductive layer is preferably 0.1 to 10 ⁷ Ω.

[0020]

【Example】

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples. All “parts” in Examples and Comparative Examples mean parts by weight.

[Example 1] Colloidal polypyrrole 10
For 0 parts, 50 parts of polyester resin (trade name “Vylonal”, manufactured by Toyobo Co., Ltd.), 40 parts of melamine resin,
A coating material was prepared by adding and mixing 10 parts of a nonionic surfactant. This paint was applied to a polyester film (trade name “Melinex S”, 1
88 μm, manufactured by Teijin Dupont Co., Ltd.) using a wire bar so that the coating amount is 0.5 g / m ^{2 in} solid content, and dried at 150 ° C. for 1 minute using a drier. A conductive intermediate layer was formed. On the conductive intermediate layer, a coating amount of a dispersion of polyethylene spherical particles (trade name “Chemipearl W-400”, manufactured by Mitsui Chemicals, Inc.) was used as a lubricant.
(Solid content?) Coating was performed using a wire bar so as to be 0.1 g / m ² and dried at 120 ° C. for 1 minute to form a lubricant layer to produce a lithographic printing plate support. A zinc oxide, a cyanine dye, and an acrylic resin were mixed on the lubricant layer on the surface of the support, and the mixture was dispersed in toluene to form a coating material having a coating weight of 20 g / m ² to form a photosensitive layer. Then, an electrophotographic planographic printing plate was obtained.

[Example 2] A dispersion of calcium stearate as a lubricant (trade name "Nopcoat C-104")
HS ", manufactured by San Nopco Co., Ltd.) to obtain an electrophotographic lithographic printing plate in the same manner as in Example 1.

Example 3 An electrophotographic lithographic printing plate was prepared in the same manner as in Example 1 except that the lubricant was an ethyl acetate dispersion of silicon powder (trade name “TOSPEARL120”, manufactured by GE Toshiba Silicone Co., Ltd.). I got

Comparative Example 1 An electrophotographic lithographic printing plate was obtained in the same manner as in Example 1 except that no lubricant was applied on the conductive intermediate layer.

In the electrophotographic lithographic printing plates manufactured by the above Examples and Comparative Examples, before coating the photosensitive layer, the surface resistance, abrasion resistance, solvent resistance,
The water resistance and the adhesion to the substrate were evaluated. After coating the photosensitive layer, the adhesion between the [conductive intermediate layer + lubricant layer] and the photosensitive layer was evaluated. The obtained printing plate was left in a dark place at a temperature of 10 ° C. and a humidity of 30% for 48 hours, and then made into a plate using a plate making machine (Elefax LP-50, manufactured by Iwasaki Tsushinki Co., Ltd.). Desensitized with liquid (Iwasaki Communication Equipment Co., Ltd.). Printing was performed with an offset printing machine using the obtained plate-making product. At this time, the degree of plate-making fog and plate-making image quality were visually evaluated, and the presence or absence of plate mark during printing was examined. The results are shown in Table 1 below.

<Scratch Resistance 1> Evaluation was made on whether the [conductive intermediate layer + lubricant layer] was peeled off from the substrate when the [conductive intermediate layer + lubricant layer] was scratched by a nail. ：: Does not peel. ×: Peeled.

<Scratch resistance 2> When the [conductive intermediate layer + lubricant layer] was rubbed with a wire bar, the evaluation was made by the number of times required until the [conductive intermediate layer + lubricant layer] was scraped off from the substrate. did. ×: within 2 times △: 3 to 10 times ○: 11 to 50 times ：: 50 times or more

<Solvent resistance> Evaluated by the number of rubs required until the [conductive intermediate layer + lubricant layer] was rubbed when the [conductive intermediate layer + lubricant layer] was rubbed with toluene impregnated into absorbent cotton. did. If the solvent resistance is poor, the conductive intermediate layer will dissolve during the coating of the photosensitive layer. ×: within 2 times △: 3 to 10 times ○: 11 to 50 times ：: 50 times or more

<Water resistance> When water is impregnated into absorbent cotton and the [conductive intermediate layer + lubricant layer] is rubbed, [conductive intermediate layer +
[Lubricant layer] was evaluated by the number of rubs required until the lubricant layer was rubbed off. If the water resistance is poor, fountain solution at the time of printing penetrates and the conductive intermediate layer dissolves, resulting in plate drop. ×: within 2 times △: 3 to 10 times ○: 11 to 50 times ：: 50 times or more

<Adhesion to Base Material> A grid of 1 mm on a side is made in a square of 1 cm square on the surface of [conductive intermediate layer + lubricant layer] with a knife, and an adhesive cellophane tape (trade name) When "Cellotape" (manufactured by Nichiban Co., Ltd.) was affixed, and the tape was peeled off after rubbing with a finger five times from above the tape, the number of grids where [conductive intermediate layer + lubricant layer] was peeled off from the base material Was evaluated. ×: 10 or more Δ: 3 to 10 times ○: 1 to 2 ◎: No peeling at all.

<Adhesion with Photosensitive Layer> After forming a photosensitive layer on the [conductive intermediate layer + lubricant layer], the surface has a side of 1 mm
Create a grid in a square of 1 cm square with a knife, paste an adhesive cellophane tape on the surface of this photosensitive layer, rub the tape five times over the tape, and then peel off the tape.
The evaluation was based on the number of grids in which the photosensitive layer was separated from the [conductive intermediate layer + lubricant layer]. ×: 10 or more Δ: 3 to 10 times ○: 1 to 2 ◎: No peeling at all.

<Plate making fog> After plate making with a plate making machine, the presence or absence of plate making fog was visually evaluated. ：: No fog is observed. ×: Fog is observed even slightly.

<Plate making image quality> Image quality after plate making was evaluated by visual judgment. ：: A level that does not cause any problem in use. X: A level in which characters are squashed, blurred, etc., and cause problems in use.

<Printing> After printing on 10,000 high-quality paper using an offset printing machine, the presence or absence of printing was checked visually. ：: No version leakage. X: The plate is slightly discolored.

[0036]

[Table 1]

When Examples 1 to 3 are compared with Comparative Examples, in the present invention in which a lubricant layer is formed, the abrasion resistance is clearly improved. Therefore, it is possible to prevent the conductive intermediate layer from being damaged by a roller or the like during transportation or coating of the photosensitive layer. The abrasion resistance and solvent resistance were best when the polyethylene particles of Example 1 were used as a lubricant. Even when a lubricant is applied on the conductive intermediate layer, the essential properties of the lithographic printing plate support, such as surface resistance and adhesion to the photosensitive layer, are maintained. As a result, plate making fog, plate The effect of applying the lubricant was not observed on the performance of plate making products such as moss.

[0038]

As can be seen from the above description, according to the present invention, by applying a lubricant on the conductive intermediate layer,
Electrophotography with a conductive intermediate layer that improves scratch resistance, prevents damage to the conductive intermediate layer during coating of the photosensitive layer, and prevents problems such as peeling, and does not affect plate making imageability or printability at all Support for formula lithographic printing plate can be provided

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Matsuda 501, Honjuku, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture Special paper manufacturing Co., Ltd. (72) Takateru Hatanaka 501, Honjuku, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture Paper Co., Ltd. Terms (reference) 2H068 AA44 AA45 AA50 AA56 BB01 BB04 BB41 BB50 BB70 FA30 FB22 2H114 AA04 AA23 BA03 DA04 DA47 DA52 DA56 DA59 DA62 DA73 DA77 EA03 FA15 FA16 GA22 GA33 GA34 GA38

Claims (5)

[Claims] 1. A conductive intermediate layer is formed by applying a coating material containing a conductive agent and a binder resin on the surface of a sheet-like base material.
A support for an electrophotographic lithographic printing plate, wherein a lubricant is further applied to the surface of the conductive intermediate layer to form a lubricant layer. 2. The support for an electrophotographic lithographic printing plate according to claim 1, wherein the lubricant is polyethylene particles. 3. The polyethylene particles having a particle diameter of 0.1.
3. The support for an electrophotographic lithographic printing plate according to claim 2, wherein the thickness is 1 to 5.0 [mu] m. 4. The method according to claim 1, wherein the polyethylene particles have a particle size of 0.1 to 0.1.
4. The support for an electrophotographic lithographic printing plate according to claim 2, wherein the support is coated with 0.5 g / m ² . 5. The support for an electrophotographic lithographic printing plate according to claim 1, wherein the conductive agent is polypyrrole or a polypyrrole derivative.