JPS59220755A - Lithographic plate - Google Patents

Abstract

PURPOSE:To obtain a printing plate of high sensitivity by forming an electrostatic printing plate having a photosensitive layer composed of a phthalocyanine (PC) pigment, and an amt. of ZnO and ZnS at least more than PC by wt., and using an ink receptive toner. CONSTITUTION:A photosensitive body 3 is obtained by forming a photoconductive layer 2 prepared by dispersing into a binder resin, a PC pigment, and ZnO and ZnS in an amt. at least more than that of PC by wt. on a conductive substrate 1. The photosensitive body 3 is electrostatically charged and exposed to semiconductor laser beams 4 modulated with an electric signal, and developed with an ink receptive toner. The PC pigment is enumerated as follows: X-type (alpha-type, beta-type) metal-free PC; epsilon-type (alpha-type, beta-type) copper PC; vanadyl PC; newly developed and finely pulverized PC deriv. treated by acid pasting and having an electron attractive group, such as nitro.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a lithographic printing plate produced by writing information in a short time on a highly sensitive photoconductive photoreceptor in which zinc oxide is dispersed in a binder resin.

Recently, with the rationalization of office work, Japanese word processors have become popular. Conventional typewriters print each character on paper, but characters entered with a word processor are first recorded as electrical signals in memory, and then read out and displayed as characters on a cathode ray tube.

On the other hand, in order to create a printing plate from electrical signals recorded in the memory of a word processor, it is necessary to print them out as a hard copy on paper using an inkjet method, thermal recording method, wire dot method, electrophotographic method, etc. This was then used as a manuscript to create a plate by charging, exposing, and fixing it onto zinc oxide master paper. However, this method requires a lot of effort and time because it involves two steps: outputting a hard copy and making a plate.Also, since the image is copied from the hard copy to the printing plate, the quality of the image on the printing plate deteriorates.

Another method is to form a plate by directly exposing a photoconductive photoreceptor to a laser beam to form a latent image, followed by development and fixing. This method uses lasers such as argon, helium neon, helium cadmium, YAG, carbon dioxide, etc., but in order to obtain the required output, the laser equipment is large and the power consumption is high relative to the output light amount. There is. Compared to these lasers, this Kuroushi conductor laser is ultra-small, high efficiency, low voltage, low power consumption, and its drive power allows high-speed modulation exceeding I GHz, making it compatible with iC and peripheral semiconductor circuits. It has characteristics such as good performance and high reliability unique to semiconductors. However, semiconductor lasers have a small output light amount, and the output wavelength is 760 to 800 for A6GaAs laser light, which is a commercially available semiconductor laser.
nm or 830 to 880 +1 m, which is a longer wavelength than that of gas laser light. Photoconductive photoreceptors sensitive to this are Cd, g-Cu, Se-Te/S
e, Amol 77-Si, and 7-thalocyanine photoreceptors, but considering that they are used as printing plates and are discarded after use, materials other than phthalocyanine are unsuitable in terms of material cost and toxicity.

However, the phthalocyanine pigment used as a phthalocyanine photoreceptor has a small average particle size of 0.005 μm and has low resistance, so in order to use it as a photoreceptor, the proportion of the dispersed resin component must be large. When a photoreceptor is manufactured using the method, the surface of the photoreceptor becomes extremely smooth, resulting in extremely poor toner fixing properties. Therefore, even if a printing plate was made, the toner would peel off during printing, making it unusable.

As a result of intensive studies to solve the above-mentioned drawbacks, the present inventors have found that, as an example of a photoreceptor, ε-type copper phthalocyanine (Al and phthalocyanine having an electron-withdrawing group or an electron-withdrawing group) is formed on a conductive support. The photoreceptor is provided with a photoconductive layer in which a mixture of a phthalocyanine having a group and another phthalocyanine and an acid-pasted phthalocyanine derivative tB) and zinc oxide are dispersed in a binder resin. A lithographic printing plate was completed by charging and imagewise exposing to form an electrostatic latent image, and developing and fixing the electrostatic latent image using an ink-receptive toner.

However, since this lithographic printing plate uses only zinc oxide as a filler and is dispersed in the photoconductive layer, it has the drawbacks of poor charge retention and dark decay properties for positive charging.

The present invention has been made to solve the above-mentioned drawbacks, and as an example of a photoreceptor, an ε-type copper phthalocyanine prisoner and a phthalocyanine having an electron-withdrawing group or an electron-withdrawing group are formed on a conductive support. A mixture of phthalocyanine and other phthalocyanines with acid pasting treated phthalocyanine derivative (B), which is provided with a photoconductive layer in which zinc oxide and zinc sulfide are dispersed in a binder resin amount. The object of the present invention is to provide a lithographic printing plate in which the photoreceptor is charged, imagewise exposed to form an electrostatic latent image, and the electrostatic latent image is developed and fixed using an ink-receptive toner. .

The present invention will now be described in detail with reference to the drawings. First, as shown in FIG. Photoconductive layer (2) dispersed in binder resin
A photoreceptor (3) is formed. Next, after the photoreceptor (3) is charged by corona irradiation with a charging device, the semiconductor laser beam (4) is modulated by an electric signal as shown in FIG. An electrostatic latent image is formed by imagewise exposure with a semiconductor laser beam (modulated by a signal), and an electrostatic latent image is formed by ink-receptive toner (5) as shown in FIG.
It is fixed as shown in Figure V to produce a lithographic printing plate (6).

The conductive support used in the present invention may be a metal plate or sheet made of aluminum, brass, copper, stainless steel, or a plastic substrate (aluminum, chromium, palladium, metal oxide, etc.) You can use vapor-deposited materials, conductive treated plastic plates, paper, etc., and metal oxide plates or sheets.

In addition, the phthalocyanine pigments used in the present invention include X-type metal-free phthalocyanine, ε-type copper phthalocyanine, α-type steel phthalocyanine, β-type copper phthalocyanine, α
Type metal-free phthalocyanine, β-type metal-free phthalocyanine, Nozonazil phthalocyanine, and phthalocyanine derivatives, which are fine particles with electron-withdrawing groups such as nitro groups, that have been processed with acid paste and developed by Shiki Honko etc. be.

Phthalocyanines having an electron-withdrawing group include metal-free or various metal phthalocyanines in which the benzene nucleus in the molecule is substituted with an electron-withdrawing group such as a nitro group, cyan group, halogen atom, sulfone group, carboxyl group, or sulboamide group. There is something. This phthalocyanine derivative can be obtained by using phthalonitrile, phthalic acid, phthalic anhydride, or phthalimide substituted with the above substituents as phthalonitrile, phthalic acid, phthalic anhydride, or phthalimide, which is a raw material for phthalocyanine during phthalocyanine synthesis, or It can be obtained by using both. The method for producing the phthalocyanine derivative is not particularly limited. Further, the number of substituents in the phthalocyanine derivative molecule is 1 to 16.

A phthalocyanine having an I-electron-withdrawing group is subjected to an undo pasting treatment with another phthalocyanine having no electron-withdrawing group, if necessary, to obtain a phthalocyanine derivative. Here, acid pasting treatment refers to the above-mentioned azurephthalocyanine having an electron-withdrawing group, or other phthalocyanine, which is treated with sulfuric acid, orthosulfuric acid, birophosphoric acid, chlorosulfonic acid, hydrochloric acid, hydroiodic acid, hydrofluoric acid, or brominated acid. A treatment method in which a salt is formed with an inorganic acid such as hydrogen acid, and the precipitated phthalonanine derivative is poured into water as known in the organic pigment industry. is obtained.

If a photoreceptor is made by coating a photoconductive material made by dispersing the phthalocyanine pigment described in Section 2 in a binder resin on a conductive support, the surface will be smooth and toner will be fixed as described above. Bad sex. Therefore, in order to improve toner fixability, we mixed a filler that mattizes the surface of the photoreceptor and tested it. As fillers, titanium oxide, calcium carbonate, cadmium carbonate, magnesium oxide, zinc oxide, and zinc sulfide were selected and tested, and the surface became matte, but most of them were compared to phthalocyanine pigment-resin photoreceptors. light sensitivity is significantly reduced, dark decay is large,
It turned out that the charge retention properties were also poor. However, in the case of dispersed zinc oxide and zinc sulfide, the average particle size of zinc oxide and zinc sulfide is about 0.6μ, which is larger than that of phthalocyanine pigments, has a large electrical resistance value, and has a dispersion resin component ratio of phthalocyanine to phthalocyanine. Since the pigment can be slightly uneven compared to the case of the pigment alone, it is possible to form minute irregularities on the surface of the photosensitive layer without reducing the photosensitivity due to zinc oxide and zinc oxide. It was found that this filler is preferable as a filler.

In addition, in the case of phthalocyanine pigment-resin photoreceptors, the phthalocyanine pigment mainly has the effect on photosensitivity.
Although the electrophotographic properties of this photoreceptor are good, the photoreceptor containing only zinc oxide as a filler has poor charge retention and dark decay properties for positive charges, and the photoconductor containing only zinc sulfide as a filler has poor charge retention and dark decay properties. Although these materials had good charge retention and dark decay characteristics against positive charges, they had the disadvantage of a large residual potential.

On the other hand, by dispersing zinc oxide and zinc sulfide, the unevenness formed increases the surface area, which improves the adhesive strength when fixing the toner onto the photoreceptor layer, making it possible to print more. let

Furthermore, as the filler, any zinc oxide that is commonly used in powder form for electrophotography can be used, and as the zinc sulfide, a general reagent can be used, and it is inexpensive and non-toxic.

The mixing ratio of the phthalocyanine pigment and (zinc oxide decasulfide 1111 lead) is phthalocyanine pigment/'(oxidation -11+
, lead zinc sulfide) = 20 to 45 wt%, zinc sulfide/zinc oxide: 1 [1 to 50 wt% was good. That is, if the phthalocyanine pigment content is less than 20 wt%, the photosensitivity for semiconductor sheets will be insufficient;
%, the fixing properties of the ink-receptive toner and its wettability with water deteriorate.7. ). Of course, the above matters are greatly influenced by the amount of binder resin added. The binder resin ratio was good when the binder resin/7 talocyanine pigment was 2 to 4 in terms of film properties, charge retention properties, and wettability with water.

Binder resin is polyester resin, polystyrene.

Thermoplastic resins such as polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl acecool, polyvinyl butyral, alkyd resins, acrylic resins, polyacrylonitrile, polycaponate, polyketone, polyurethane, and epoxy resins. For printing plates that require dampening water, resins with hydrophilic groups are suitable, such as polyvinyl alcohol, polyvinylpyrrolidone, polyamide, polyacrylic chemide, etc. , polyvinyl acetate, polyvinyl formal, polyvinyl butyral, phenolic resins, etc. give particularly good results.

Solvents used in the production of photoreceptors include aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, alcohols such as methanol, ethanol, and isopropanol, ethyl acetate, and methyl cellosol. esters such as carbon tetrachloride, chloroform, halogenated hydrocarbons such as dichloromethane, tetrahydrofuran,
Ethers of cyoxane, dimethylformamide, dimethyl sulfoxide, etc. may be used.

There are various methods of manufacturing the photoreceptor used in the present invention. For example, the phthalocyanine pigment, binder resin, and solvent are dispersed in a ball mill for 10 hours, and then zinc oxide and zinc sulfide powder are added for another 6 hours. There is a method of dispersing the photosensitive agent and coating the obtained photosensitive agent on a conductive support. Dispersion methods include, in addition to the above-mentioned ball mill, paint conditioner, ultrasonic dispersion, and the like. In addition, as a coating method, methods such as an applicator, spray coater, bar coater, dip coater, and doctor blade can be used, and they are used depending on the viscosity, finishing agent, and amount of coating.

The above photoreceptor only emits visible light in the range of 400 to 700 nm (
Exposure is also possible with infrared light exceeding 700 nm. Therefore, in the present invention, conventional general exposure methods and light sources can be used. As for the exposure method, the photosensitivity of this photoreceptor is significantly higher than that of conventional products, and the sensitive wavelength range is 700 nm.
Considering the above factors, the ability to directly extract electrical signals from a word processor, etc., the most suitable method is to directly expose the photoreceptor to semiconductor laser light modulated by electrical signals.

After development, an ink-receptive toner is selectively adhered to the latent image formed by image exposure on the photoreceptor to form a toner image (-after which the toner image is heated and fixed. Among the lithographic printing plates that have been developed, in the lithographic printing plate that uses brewed water, the surface of the photoreceptor is uneven, so fixing can be easily carried out by heating.

As a resin for ink receptive toner, it is highly insulating and has a relatively low molecular weight, and it forms a chemical bond with the photoconductive layer during heat fixing.
It is also necessary to have compatibility with the dispersion resin of the photoconductive layer, and in particular, since the ink adheres to the ink-receptive toner after fixing, a resin similar to the ink composition is particularly preferred. Suitable resins for this purpose include phenolic resins, polyester resins, styrene and maleic anhydride copolymer resins, polyamides, and drying oil-modified alkyd resins.

Ink-receptive toner for dry developers consists of a charge control agent such as an electron-accepting organic complex, a colorant such as carbon blank, and an appropriate resin, and in the case of a two-component system, it is mixed with a carrier such as iron powder. In the case of a -component system, the gear is non-JTI, and generally consists of magnetite, a charge control agent, a coloring agent such as carbon black, and an appropriate resin.

As an ink-receptive toner for wet-type printing agents, it is preferable to use one prepared by dispersing a car pump rack resin, a charge control agent, etc. in an isoparaffinic petroleum solvent.

The present invention will be explained in more detail with reference to Examples below.

(Example 1) Canon semiconductor laser beam printer LI3p
-io was modified as follows. First, input (J
A Flora Peach Iscree-4°h and an interface circuit were attached to the LBP-10 to read electrical signals such as characters input from the keyboard and stored on the floppy disk, making it possible to input them to the LBP-10. In addition, the photosensitive drum was replaced with an aluminum drum, grooves were made in the drum, hooks were placed in two places, and the lithographic plate material was wrapped around the drum so that it could be fixed with hooks at the front and back, and a positive charging device was installed. only worked.

Subsequently, 40 g of copper phthalocyanine and 0.5 g of tetranitrocopper phthalocyanine were dissolved in 500 g of 98% concentrated sulfuric acid with thorough stirring. The dissolved solution was mixed with 5 quarts of water to precipitate a composition of copper phthalocyanine and tetranitrocopper phthalocyanine, followed by filtration, washing with water, and drying at 120° C. under reduced pressure. The composition (5) thus obtained was treated with ε-type copper phthalocyanine (Lionol B manufactured by Toyo Ink Manufacturing Co., Ltd.).
5ag was mixed with 100g of ER) and dispersed in 5kg of methanol to obtain a homogeneous mixed dispersion. Thereafter, it was passed through the mouth and dried at 120° C. under reduced pressure to obtain a mixed composition (B).

A photoconductive composition was prepared based on the following formulation.

, Mixed composition (B) 10. ? 1"°7 resin (Shin-Etsu Chemical Co., Ltd." KR-214) 2
18g; Acrylic resin (Aron S' 1001 manufactured by Toagosei Kagaku Co., Ltd.)
2g j F,,F 67g After dispersing the above composition in a magnetic ball mill for 48 hours, photoconductive zinc oxide (manufactured by Sakai Chemical Co., Ltd. 5AZEX2)
3 g of O o o ) and 29 g of reagent zinc sulfide (manufactured by Kanto Kagaku Co., Ltd.) were added and further dispersed in a ball mill for 6 hours. Next, the obtained mixed solution was again diluted with toluene to lower the viscosity, and was roll coated onto aluminum foil with a thickness of 5 μm, polyester film with a thickness of 75 μm, and aluminum foil of a laminate film to a dry film thickness of 8 μm. 8 at 50℃
The electrophotographic photoreceptor and 1- are dried for a while. A corona discharge was applied to the sample thus obtained at a charging speed of -1-5,'7 KV, a corona gap of 1 o mm, and a charging speed of 1 o m/min.
Exposure was performed using a tungsten light source at 854' with an illuminance of 10 Lux.

The amount of light irradiation required for the potential immediately before exposure to decrease by 50% at this time was defined as the sensitivity.

The sample measured in this way has a sensitivity of 1.5 Lux-
5 ec, and the sensitivity showed a sufficient value.

This photoreceptor was grounded to the aluminum drum and used as a hook in a laser printer. then 70
The laser printer was operated by inputting an electric signal from the soapy disk reader, and after charging, an image was exposed on the photoreceptor by a semiconductor laser.

Next, the atomized photoconductor was removed from the aluminum drum, and a negative type toner 1) N-1 manufactured by Tomoe Paper Manufacturing Co., Ltd. was applied.
o and carrier EJ” V150/250 manufactured by Nippon Tetsuko Co., Ltd.
Positive development was carried out by a magnetic brush method using an ink-receptive toner consisting of: Thereafter, the toner image was fixed by heating to produce a printing plate for lithographic printing.

Next, the surface of this printing plate was moistened with a pretreatment liquid containing gum arabic and phosphoric acid, and after drying, double-sided tape was attached to the plate cylinder of a Ryobi offset printing machine 2800C'D. Printing was carried out on high-quality paper (46 plate 70 kg) using offset process ink G set sumi and dampening water at a printing pressure of 0.30 mm (4000 rotations/hour)
,,The density at the beginning of printing was low, but after rubbing 60 sheets, the density of the solid area improved to 14 or more, and a good print was obtained (
1ooo.

).

(Example 2) As phthalocyanine, 2 g of methyl ethyl ketone 26I and Cellsolve Acetate 269 were added to 2 g of mixed composition fat (Ebicor 471007 manufactured by Shell Chemical Co., Ltd.) of (Example 1).
After kneading and kneading in a porcelain ball mill for 48 hours, photoconductive acid/zinc oxide (manufactured by Sakai Kagaku Co., Ltd. 5AZEX2 o
o) was added with 2g of 14gk reagent zinc sulfide (manufactured by Kanto Kagaku Co., Ltd.), and further kneaded in a porcelain ball mill for 10 hours. Next, the obtained composition was placed on a 100 tt aluminum plate.
It was applied to a thickness of 3 μm and dried at 160° C. for 30 minutes to obtain a photoreceptor.

This photoreceptor is positively charged by corona discharge (+6 KV), and the original positive film is projected and exposed at 10 lux for 15 seconds using 100W tungsten light for enlargement to form an electrostatic latent image on the photoreceptor. It was developed with the same ink receptive l.colorner as in Example 1. Thereafter, fixation was performed by heating to produce a printing plate for lithographic printing.

Thereafter, printing was carried out by the offset printing method using dampening water in the same manner as in Example 1 to obtain similar printed matter.

The present invention has the above-described configuration. For example, it is possible to obtain printed matter by exposing an image directly onto a photoconductor from the memory of a word processor without making a hard copy on paper, thereby reducing processing time. Furthermore, since the photoreceptor has high sensitivity, the exposure time is short, and plate making can be performed without degrading image quality, resulting in high quality printed matter.

[Brief explanation of the drawing]

Figure 1 shows phthalocyanine pigments (zinc oxide + zinc sulfide)
An explanatory diagram showing a state in which a system photoreceptor is charged by corona irradiation, Fig. 2 is an explanatory diagram showing a state in which an electrostatic latent image is formed by imagewise exposure to light, and Fig. 6 is an explanatory diagram showing a state in which an electrostatic latent image is formed by imagewise exposure to light. FIG. 4 is an explanatory diagram showing a fixed photoreceptor. (Season...Electroconductive support (2)...Photoconductive layer (3)...Phthalocyanine pigment-(zinc oxide + zinc sulfide) photoreceptor (4)...Light (5)... Ink-receptive toner (6)...lithographic printing plate patent applicant Toppan Printing Co., Ltd. Tadzu/P)

Claims (2)

[Claims] (1) The photoreceptor has a photoconductive layer on a conductive support, in which a phthalocyanine pigment and a mixture of zinc oxide and zinc sulfide in a weight ratio at least greater than that of the pigment are dispersed in a binder resin. A lithographic printing plate comprising: charging the photoreceptor using a photoreceptor, imagewise exposing it to form an electrostatic latent image, and then developing and fixing the electrostatic latent image using an ink-receptive toner. (2) The lithographic printing plate according to claim 1, wherein imagewise exposure is performed using a semiconductor laser modulated by an electric signal.