JPH0364065B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention provides a photoconductive layer containing a phthalocyanine pigment containing 10 to 50% by weight of zinc oxide and a photoconductive layer containing zinc oxide as a photoconductor element. The present invention relates to an offset master for semiconductor laser exposure provided with a photoconductive layer containing a phthalocyanine pigment and zinc oxide as photoconductor elements. [Technical background of the invention and its problems] 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 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 first print them onto paper using an inkjet method, thermal recording method, wire dot method, electrophotographic method, etc. This was output as a copy, and 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 large relative to the output light amount. There is. In this respect, semiconductor lasers are ultra-small compared to these lasers.
High efficiency, low voltage, low power consumption and drive current
Features include high-speed modulation exceeding 1 GHz, good compatibility with peripheral semiconductor circuits such as ICs, and high reliability unique to optical conductors. However, the output light intensity of semiconductor lasers is small, and the output wavelength of AlGaAs laser light, which is a commercially available semiconductor laser, is 760 ~
It has a longer wavelength of 800 nm or 830 to 880 nm compared to gas laser light. Photoconductive photoreceptors that are sensitive to this include CdS-Cu, Se-Te/Se, amorphous Si, and phthalocyanine photoreceptors, but considering that they are used as offset master plates and discarded after use, the material cost is low. In terms of hygiene, materials other than phthalocyanine are inappropriate. However, the phthalocyanine pigment used as a phthalocyanine photoreceptor has a small average particle size of 0.05 μm.
Due to its low resistance, in order to use it as a photoreceptor, it is necessary to increase the ratio of dispersed resin components, and if a photoreceptor is made from phthalocyanine pigment alone, the surface of the photoreceptor will be extremely smooth due to the large amount of resin. It could not be used as an offset master plate because of its poor wettability and water retention properties. One of the important properties that an offset master plate must have is hydrophilicity. When a toner image is formed on a photoreceptor provided with a photoconductive layer to form an offset master plate, the toner image area becomes ink receptive, and the non-image area (photoconductive layer surface) has ink repellency, that is, hydrophilicity. It must be able to hold water. A typical conventional offset master version is zinc oxide master.
Zinc oxide fine powder is dispersed in the photoconductive layer, and the average particle size of zinc oxide is 0.3 μm, which is an order of magnitude larger than that of phthalocyanine pigments. Zinc oxide fine powder can be made hydrophilic using a so-called etchant containing ferricyanide salt, ferrocyanide salt, and phosphate as main components. However, commercially available zinc oxide masters are sensitive only to visible light. [Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to improve electrophotographic properties such as acceptance potential, dark decay, and semiconductor laser sensitivity, and hydrophilization processing properties (etch processing properties). ) An object of the present invention is to provide a good phthalocyanine-based offset master for semiconductor laser exposure. [Progress until the problem was solved] Aiming to develop an offset master for semiconductor laser exposure, the present inventors developed a phthalocyanine pigment that is sensitive to semiconductor lasers, fine zinc oxide powder for hydrophilic treatment, and a binder. We considered combining dielectric resins. First, as a preliminary experiment, we started by determining the content of zinc oxide fine powder necessary for hydrophilic treatment.
The general theory is that during etching with an etchant, zinc oxide reacts with the ferrocyanide salt or ferricyanide salt in the etchant to form a hydrophilic and insoluble salt, resulting in desensitization. As zinc oxide fine powder, manufactured by Sakai Chemical Co., Ltd.
Using SAZEX 2000, acrylic resin Arotap 3211 manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd. as a binder resin, and methyl ethyl ketone as a solvent, a dispersion coating liquid was prepared using a paint sheaker containing glass beads. Dispersion coating solutions were prepared with varying ratios of zinc oxide and binder resin, and each was applied to a polyester film (thickness 150 μm) manufactured by Toray Industries, Inc. using a wire bar to a film thickness of approximately 15 μm. Each coated film was passed twice through an AM Multigraphics Master Converter 124 etching machine containing a standard Ryobi etchant and then printed on a Ryobi 2800CD compact offset printer. Vanson 1980 ink was used. The results are shown in Table 1. 〇 indicates that the fed blank paper was the same whiteness after printing as before printing (no background fog), △ indicates that it was slightly dirty, and × indicates that it was very dirty. .

[Table] If the etchant had completely made it hydrophilic, water would be retained on the ZnO-resin layer and ink would not adhere. A similar experiment was carried out using acrylic resin tire knurl #009 manufactured by Mitsubishi Rayon Co., Ltd., with different types of binder resin.
Polyester resin Vylon #200 manufactured by Toyobo Co., Ltd.
The test was also carried out using the epoxy resin Epicoat #1004 manufactured by Shell Petrochemical Co., Ltd., and although there were some differences, the results were almost the same as those shown in Table 1.
Therefore, it can be concluded that the effect of the type of binder resin on hydrophilization can be ignored, and that it is simply the zinc oxide content that controls hydrophilization.
Table 1 shows that good hydrophilicity can be obtained when the zinc oxide content is 70% by weight or more. Next, as a phthalocyanine pigment, ε-type copper phthalocyanine Lionol Blue manufactured by Toyo Ink Manufacturing Co., Ltd.
ER was selected, mixed and dispersed with zinc oxide and a binder resin in the same manner as described above, and similarly applied to a polyester film (thickness: 150 μm) to conduct an experiment to make it hydrophilic. The phthalocyanine pigment is a binder resin (acrylic resin Arotap3211 manufactured by Nippon Shokubai Co., Ltd.)
The ratio of zinc oxide was varied by always adding 30% by weight. The evaluation method is the same as described above. The results are shown in Table 2. Table 2 shows that good hydrophilicity can be obtained when the zinc oxide content is 60% by weight or more. Compared to Table 1, the fact that good hydrophilicity can be obtained even when the content of zinc oxide is 5 to 10% less by weight indicates that it is the binder resin that is most inhibiting hydrophilicity. It shows.

[Detailed description of the invention]

Hereinafter, to explain in detail with reference to the drawings, the offset master for semiconductor laser exposure of the present invention, as shown in FIG. )-provide a photoconductive layer A of a binder resin, on this photoconductive layer A,
Phthalocyanine pigment - zinc oxide (60-85% by weight)
- A photoconductive layer B of a binder resin is provided. The phthalocyanine pigments used in the photoconductive layer A and photoconductive layer B of the present invention may be the same or different types, or may be a mixture of two or more types of phthalocyanine pigments, and the phthalocyanine pigments include: There are metal-free phthalocyanine pigments and various metal phthalocyanine pigments, and various crystal forms are used. Examples of metal phthalocyanine pigments include copper phthalocyanine, tin phthalocyanine, aluminum phthalocyanine, nickel phthalocyanine, cobalt phthalocyanine, zinc phthalocyanine, vanadyl phthalocyanine, etc.
It is preferable to select a material that is sensitive in the infrared region, such as type copper phthalocyanine. In addition, when a phthalocyanine derivative having an electron-withdrawing group such as a nitro group is acid-pasted, TNF
Practically sufficient sensitivity can be obtained without using sensitizers such as sensitizers. Examples of phthalocyanine having an electron-withdrawing group include a halogen atom, a nitro group, a cyano group, a sulfone group, a carboxyl group,
It is substituted with an electron-withdrawing group such as a sulfamide group or a carboamide group. This phthalocyanine derivative can be obtained by using phthalonitrile, phthalic acid, phthalic anhydride, or phthalimide substituted with the above-mentioned substituents as the raw material for phthalocyanine during phthalocyanine synthesis; It can be obtained by using both. The method for producing the phthalocyanine derivative is not particularly limited. Further, the number of substituents in one molecule of the phthalocyanine derivative is 1 to 16. The above-mentioned phthalocyanine having an electron-withdrawing group is subjected to acid pasting treatment with other phthalocyanine having no electron-withdrawing group, if necessary, to obtain a phthalocyanine derivative. Here, acid pasting treatment refers to phthalocyanine or other phthalocyanine having the above-mentioned electron-withdrawing group to This is a treatment method in which a salt is formed with an inorganic acid such as an acid, and the phthalocyanine derivative is poured into water as known in the organic pigment industry, and the precipitated phthalocyanine derivative is filtered, washed with water, and dried. can get. This phthalocyanine derivative can be used in combination with other phthalocyanines, and desired sensitivity can be obtained by selecting the composition. The binder resins of photoconductive layer A and photoconductive layer B may be the same or different types, or may be a mixture of two or more types of binder resins, and the binder resin may be melamine. resin, butyral resin,
Epoxy resin, silicone resin, polyurethane resin,
Known materials having insulating properties such as acrylic resins, xylene resins, vinyl chloride-vinyl acetate copolymer resins, polycarbonate resins, and cellulose derivatives having a volume resistivity of 10 ⁷ Ωcm or more are used. In addition, as a solvent, aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene,
Ketones such as acetone, methyl ethyl ketone, and cyclohexanone, alcohols such as methanol, ethanol, and isopropanol, esters such as ethyl acetate and methyl cellosolve, halogenated hydrocarbons such as carbon tetrachloride, chloroform, and dichloromethane, and ethers such as tetrahydrofuran and dioxane. , dimethylformamide, dimethyl sulfoxide, etc. are used. The offset master for semiconductor laser exposure of the present invention has a photoconductive layer formed on a conductive support, and the conductive support may include aluminum,
Metal plates such as nickel, aluminum, metals such as nickel vacuum-deposited on paper or plastic film, materials made by laminating metal foil such as aluminum with paper or plastic film, carbon-containing paper, organic or inorganic Low-resistance paper treated with a conductive treatment agent can be used. [Effects of the Invention] Since the offset master for semiconductor laser exposure of the present invention has a two-layer photoconductive layer having the above-mentioned structure, it has good electrophotographic properties such as acceptance potential, dark decay, and semiconductor laser sensitivity. Moreover, the hydrophilic treatment properties (etching treatment properties) are also good, and as a result, a large number of good printed materials can be produced. [Example] The present invention will be further explained below by giving examples. In the examples, "parts" indicate parts by weight. Example 1 40 parts of copper phthalocyanine and 0.5 part of tetranitrocopper phthalocyanine were dissolved in 500 parts of 98% concentrated sulfuric acid with thorough stirring. Pour the dissolved solution into 5000 parts of water to precipitate a composition of copper phthalocyanine and tetranitrocopper phthalocyanine, wash with water, and heat at 120°C under reduced pressure.
It was dried. 100 parts of the thus obtained composition [] was mixed with 100 parts of ε-type copper phthalocyanine (Lionol Blue ER) manufactured by Toyo Ink Manufacturing Co., Ltd., and dispersed in 5000 parts of methanol to form a uniformly mixed dispersion. Thereafter, it was filtered and dried at 120°C under reduced pressure to obtain a mixture []. Next, 5 parts of the above mixture [], 15 parts of acrylic polyol (Takerakku UA-702, manufactured by Takeda Pharmaceutical Co., Ltd., solid content 50% by weight), and 2 parts of epoxy resin (Siel Chemical Co., Ltd., Epicoat #1007, solid content 70% by weight) were added. Methyl ethyl ketone 28 parts, Cellsolve Acetate 28 parts
After 48 hours of kneading in a magnetic ball mill, 17 parts of zinc oxide SAZEX2000 manufactured by Sakai Chemical Co., Ltd. was added for 9 hours, and 5 parts of isocyanate (Coronate L manufactured by Nippon Polyurethane Industries, solid content 75% by weight) was added. In addition, it was kneaded in a magnetic ball mill for 1 hour, and then coated with a wire bar to form a polyester film (Metal Me, manufactured by Toray Industries, Inc.) on which aluminum was vapor-deposited.
It was coated on top to a thickness of 10 μm and dried at 130°C for 30 minutes. The proportion of zinc oxide in the photoconductive layer of this photoreceptor was 49% by weight. Next, 40 parts of metal-free phthalocyanine and 1.5 parts of mononitro copper phthalocyanine were dissolved in 1000 parts of 98% concentrated sulfuric acid with thorough stirring. Add the dissolved liquid to 10,000 ml of water.
After the phthalocyanine composition was precipitated, it was filtered, washed with water, and dried at 120°C under reduced pressure.
For the thus obtained composition [] and 100 parts of ε-type copper phthalocyanine (Lionol Blue ER),
100 parts were mixed and dispersed in 5000 parts of methanol to form a uniform dispersion. Then filtered at 120℃ under reduced pressure.
and dried to obtain a mixture [ ]. 5 parts of the above mixture [] and silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd.)
KR211 solid content 70% by weight) 15 parts, acrylic resin (Toagosei Kagaku Aron S1001 solid content 50% by weight)
Add 3 parts and 51 parts of toluene, and mix with a magnetic ball mill to 30
After time dispersion, 26 parts of photoconductive zinc oxide (SAZEX2000 manufactured by Sakai Chemical Co., Ltd.) was added, and an additional 10
The time-dispersed mixed solution was applied onto the photosensitive layer using a wire bar so that the dry film thickness was 4 μm, and dried at 130° C. for 30 minutes to obtain an electrophotographic photoreceptor. The ratio of zinc oxide in the upper photoconductive layer of the electrophotographic photoreceptor thus obtained was 60% by weight, while the temperature was +6.0KV, the corona gap was 10mm,
Corona discharge is applied at a charging speed of 10 m/min.
Spectrometer (G250 manufactured by Nippon Kogaku Co., Ltd.) 5 seconds after the discharge stops
The sample was exposed to light with a wavelength of 800 mm (2 μW/cm ² ). 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 measurement was performed using an electrostatic copying paper testing device (SP428 manufactured by Kawaguchi Electric Co., Ltd.). The sensitivity of the sample measured in this way is
The sensitivity was 2.1 μJ/cm ² and showed sufficient sensitivity to the wavelength and light intensity of the semiconductor laser light. Next, an image forming method using the above photoreceptor will be described. As the device, a semiconductor laser beam printer LBP-10 manufactured by Canon Inc. was modified as follows. First, a floppy disk reader and interface circuit were installed on the input side to read out electrical signals such as characters entered from the keyboard and stored on the floppy disk, making it possible to input into the LPB-10. In addition, the photosensitive drum was replaced with an aluminum drum, and
A groove was made in the drum, two hooks were attached to the groove, and the photoreceptor was wrapped around the drum so that it could be fixed with hooks at the front and back, and only the positive charging device would function. Using the above device, fill the developer with the developer (positive toner for offset printing) of the fully automatic electronic copying plate machine Elephax PM-40 manufactured by Iwasaki Tsushinki Co., Ltd., and attach the photoreceptor to the aluminum drum with a ground connection. After operating the laser printer and performing positive charging, exposure of the image area with semiconductor laser light, reversal development with positively charged liquid toner for offset printing, and fixing with warm air drying, the plate is removed from the aluminum drum and the offset master plate is placed. I made it. Next, I added commercially available Ryobi etching liquid.
Etching machine manufactured by AMM Multigraphics
After passing through Master Converter 124 twice, it was printed on Ryobi's small offset printer 2800CD.
Printing with Vanson 1980 ink (4000 revolutions/hour) resulted in more than 3000 good prints. Example 2 40 parts of copper phthalocyanine and 0.5 part of tetracyanocobalt phthalocyanine were dispersed in 2000 parts of glacial acetic acid,
10 parts of 98% sulfuric acid was added dropwise with stirring, and after stirring for 10 hours, the solid matter was filtered out and ammonia gas was passed through to precipitate a phthalocyanine composition, which was then washed with water and dried at 120°C under reduced pressure. The thus obtained composition [] was mixed based on the following recipe. Composition [] 5 parts ε-type copper phthalocyanine (manufactured by Toyo Ink Mfg. Co., Ltd.)
Lionol Blue ER) 5-branched polyester polyol (Desmophene #800 manufactured by Nippon Polyurethane Industries, solid content 75% by weight)
20 parts Cellsolve acetate 45 parts The above composition was milled in a magnetic ball mill at room temperature for 24 hours, then photoconductive zinc oxide (manufactured by Sakai Chemical Co., Ltd.)
After adding 5 parts of SAZEX200) and further kneading, 20 parts of isocyanate (Coronate L manufactured by Nippon Polyurethane Industries Co., Ltd. solid content 75% by weight) was added and mixed. Using a wire bar, the water-soluble resin was mixed. Coated to a thickness of 11 μm on casein-coated carbon paper (145 μm thick) and heated at 120°C.
and dried for 5 minutes. The proportion of zinc oxide in the photoconductive layer of this photoreceptor was 11% by weight. Next, add 50 parts of trinitro copper phthalocyanine to 98%
It was dissolved in 600 parts of concentrated sulfuric acid with thorough stirring. The dissolved solution was poured into 6000 parts of water to precipitate a composition of α-trinitrone copper phthalocyanine, which was then filtered, washed with water, and dried at 120° C. under reduced pressure. 100 parts of the composition thus obtained and 100 parts of ε-type copper phthalocyanine were mixed with 5000 methanol.
A homogeneous mixed dispersion liquid was obtained. Thereafter, the mixture was filtered and dried at 120℃ under reduced pressure.
And so. 3 parts of the above mixture [] and acrylic resin (Nippon Shokubai Kagaku Co., Ltd. Arotap3211 solid content 50% by weight)
6 parts, 31 parts of methyl ethyl ketone, 15 parts of n-butyl alcohol, and 15 parts of cellosolve acetate were dispersed in a magnetic ball mill for 30 hours, and then 30 parts of photoconductive zinc oxide (SAZEX2000, manufactured by Sakai Chemical Co., Ltd.) was added. Further, the mixed solution dispersed for 10 hours was applied onto the photosensitive layer using a wire bar so as to have a dry film thickness of 4 μm, and dried at 120° C. for 5 minutes to obtain an electrophotographic photoreceptor. The ratio of zinc oxide in the upper photoconductive layer of the photoreceptor thus obtained was 85% by weight, and the electrophotographic properties were measured in the same manner as in Example 1.
The photosensitivity at a wavelength of 800 nm was 2.3 μJ/cm ² .
Using this photoreceptor, an offset master plate could be made using the same equipment, materials, and method as in Example 1. Furthermore, with this master version,
Using the same method as in Example 1, more than 3,000 good offset prints could be obtained. Example 3 ε-type copper phthalocyanine (manufactured by Toyo Ink Mfg. Co., Ltd.)
Lionol Blue ER) 6 parts polycarbonate resin (Iupilon S-3000 manufactured by Mitsubishi Gas Chemical Co., Ltd.) 12 parts dichloromethane 37 parts 1,2-dichloroethane 37 parts The above composition was kneaded in a paint shaker for 1 hour, and then mixed with zinc oxide. (SAZEX manufactured by Sakai Chemical Co., Ltd.
#2000) was added and kneaded for an additional 30 minutes to obtain a photoconductive paint. This paint was applied to a thickness of 8 μm using a wire bar on carbon paper (thickness: 145 μm) coated with casein as a water-soluble resin, and dried at 120° C. for 5 minutes. The ratio of zinc oxide in the photoconductive layer of this photoreceptor is 31
Weight%. Next, the following photoconductive composition was manufactured. Composition of Example 1 [] 4-part butyral resin (Eslec B manufactured by Sekisui Chemical Co., Ltd.)
9 parts ethyl alcohol 60 parts
#2000) was added and kneaded for further 30 minutes to obtain a photoconductive composition. This photoconductive composition was coated onto the photoreceptor using a wire bar to a dry film thickness of 7 μm, and dried at 80° C. for 5 minutes to obtain a photoreceptor for semiconductor laser exposure. The ratio of zinc oxide in the upper photoconductive layer of the photoreceptor thus obtained was 68% by weight, and its electrophotographic properties were measured in the same manner as in Example 1. The light sensitivity was 2.2 μJ/cm ² . A device similar to that of Example 1 using this photoreceptor,
By using the materials and methods, it was possible to create an offset master version. Furthermore, using this master plate, it was possible to obtain more than 3,000 good offset prints in the same manner as in Example 1. Comparative Example 1 In the photoconductor of Example 3, when the photoconductor had a structure in which the upper photoconductive layer and the lower photoconductive layer were exchanged, image formation was possible using a semiconductor laser, but
When used as an offset master version, use the same etching solution and etching machine as in Example 1.
Even if you print more than 10 times, the background smear cannot be resolved.
Good prints could not be obtained. Comparative Example 2 In the photoreceptor of Example 2, when the ratio of zinc oxide in the upper photoconductive layer was set to 90% by weight, not only the electrophotographic properties deteriorated but also the film strength of the photoconductive layer decreased. It became unusable. Comparative Example 3 The photoreceptor of Example 1 in which the lower photoconductive layer was removed and the upper photoconductive layer was formed with a thickness of 15 μm had a low charging ability and could not be put to practical use.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the structure of an offset master for semiconductor laser exposure according to the present invention. 1... Conductive support, A, B... Photoconductive layer.

Claims (1)

[Claims] 1 In an offset master for semiconductor laser exposure using a phthalocyanine pigment and zinc oxide as a photoconductor element, the lower layer is a photoconductive layer A in which a phthalocyanine pigment and zinc oxide are dispersed in a binder resin, and the upper layer is a photoconductive layer A in which a phthalocyanine pigment and zinc oxide are dispersed in a binder resin. A photoconductive layer B is provided in which the photoconductive layer B is dispersed in a binder resin, and the photoconductive layer A has a zinc oxide ratio of 10 to 50% by weight, and the photoconductive layer B has a zinc oxide ratio of 60 to 85% by weight. An offset master for semiconductor laser exposure characterized by: