JPH0364064B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to an offset master for semiconductor laser exposure using a phthalocyanine pigment and zinc oxide as a photoconductor element. This invention relates to an offset master for semiconductor laser exposure. [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 a phthalocyanine-based offset master for semiconductor laser exposure, the present inventors developed a phthalocyanine pigment that is sensitive to semiconductor lasers, a zinc oxide fine powder for hydrophilic treatment, and We considered combining dielectric resin as a binder. 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. Manufactured by Sakai Chemical Co., Ltd. as zinc oxide fine powder.
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 manufactured by Nippon Shokubai Chemical Co., Ltd.).
Arotap 3211) was always added at 30% by weight, and the ratio of zinc oxide was varied. 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. A photoconductive layer 2 is provided, and a second photoconductive layer 3 in which a phthalocyanine pigment and 60 to 85% by weight of zinc oxide are dispersed in a binder resin is further provided on the first photoconductive layer 2. . The phthalocyanine pigments used in the first photoconductive layer 2 and the second photoconductive layer 3 of the present invention may be the same or different types, or may be a mixture of two or more types of phthalocyanine pigments. Pigments include metal-free phthalocyanine pigments and various metal phthalocyanine pigments, and those in various crystal forms are used. Examples of metal phthalocyanine pigments include copper phthalocyanine, tin phthalocyanine, aluminum phthalocyanine,
Examples include nickel phthalocyanine, cobalt phthalocyanine, zinc phthalocyanine, and vanadyl phthalocyanine, but it is preferable to select one that is sensitive in the infrared region, such as ε-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 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 the first photoconductive layer 2 and the second photoconductive layer 3 may be the same or different types, or may be a mixture of two or more types of binders.
Binder resins include melamine resin, butyral resin, epoxy resin, silicone resin, polyurethane resin, acrylic resin, xylene resin, and vinyl chloride.
The volume resistivity of vinyl acetate copolymer resin, polycarbonate resin, cellulose derivatives, etc. is 10 ⁷ Ωcm.
A known material having the above insulation properties is used.
Examples of solvents include 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, and tetrachloride. Carbon, halogenated hydrocarbons such as chloroform and dichloromethane, ethers such as tetrahydrofuran and dioxane, and dimethylformamide, dimethyl sulfoxide and the like 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 tetracyanocobalt phthalocyanine were dispersed in 200 parts of glacial acetic acid,
10 parts of 98% sulfuric acid was added dropwise with stirring, and the mixture was stirred for 10 hours. The solid matter was filtered off, and the phthalocyanine composition was precipitated through ammonia gas, washed with water, and dried at 120°C under reduced pressure. . The composition thus obtained was mixed according to the following recipe. Composition [] 3 parts ε-type copper phthalocyanine (manufactured by Toyo Ink Mfg. Co., Ltd.)
Lionol Blue ER) Bipartite branched polyester polyol (Desmofene #800 manufactured by Nippon Polyurethane Industries, solid content 75% by weight)
9 parts Cellsolve acetate 77 parts The above composition was milled in a magnetic ball mill at room temperature for 24 hours, and then 9 parts of isocyanate (Coronate L manufactured by Nippon Polyurethane Industries Co., Ltd. solid content 75% by weight) was added.
Using a bar coater, add and mix the mixed solution.
It was applied to a thickness of 10 μm on a polyester film (Metal Me, manufactured by Toray Industries, Inc.) on which aluminum had been vapor-deposited, and placed in an oven uniformly heated to 120° C. for 30 minutes to dry and harden to form a charge transfer layer. Next, 40 parts of copper phthalocyanine and 0.5 parts 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, then filter and wash with water.
It was dried at 120°C under reduced pressure. 50 parts of the composition thus obtained and ε-type copper phthalocyanine (Lionol Blue manufactured by Toyo Ink Mfg. Co., Ltd.)
100 parts of ER) were dispersed in 5,000 parts of methanol to form a uniform mixed dispersion. Then filter and under reduced pressure
The mixture was dried at 120°C to form a mixture [], and a photoconductive composition was prepared based on the following formulation. Mixture [] 8 parts Acrylic polyol (Takerakku UA-702 manufactured by Takeda Pharmaceutical Co., Ltd. Solid content 50%) 9 parts Epoxy resin (Siel Chemical Co., Ltd. Epicoat #1007 Solid content 70%) 5 parts Methyl ethyl ketone 20 parts Cellsolve acetate 20 After kneading the above composition in a porcelain ball mill for 48 hours, zinc oxide (SAZEX#2000 manufactured by Sakai Chemical Industry Co., Ltd.)
38 parts were added and kneaded for further 10 hours to obtain a photoconductive composition. This photoconductive composition was coated on the charge transfer layer using a bar coater to a dry film thickness of 5 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 70% by weight,
On the other hand, +6.0kV, corona gap 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
It was exposed to light (2 μW/cm ² ) with a wavelength of 800 nm. 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 2.3 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 input from the keyboard and stored on the floppy disk, making it possible to input them to the LBP-10. In addition, we replaced the photosensitive drum with an aluminum drum, made a groove in the drum, attached two hooks there, wrapped the photosensitive drum around the drum, and fixed it with hooks at the front and back.We also installed a positive charging device. only worked. 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., attach the photoreceptor to the aluminum drum with a ground connection, and use the laser. After operating the printer, performing positive charging, exposing the image area with semiconductor laser light, reversal development with positively charged liquid toner for offset printing, and fixing with hot air drying, it is removed from the aluminum drum and an offset master plate is created. Ivy. Next, I added commercially available Ryobi etching liquid.
Etching machine manufactured by AM Multigraphics
After passing through Master Converter 124 twice, it was printed on Ryobi's small offset printer 2800CD.
Printing using Vanson 1980 ink (4000 revolutions/hour) resulted in more than 3000 good prints. Comparative Example 1 In the photoreceptor of Example 1, when the ratio of zinc oxide in the upper photoconductive layer was set to 55% by weight, the electrophotographic properties were good and images could be formed using a semiconductor laser, but offset When used as a master plate, it was necessary to pass it through at least 10 times using the same etching liquid and etching machine as in Example 1. Also, because the number of etchings was large, the density of the printed matter could not be increased during printing. Comparative Example 2 In the photoreceptor of Example 1, 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, making it impractical for practical use. It became unusable. Comparative Example 3 The photoreceptor of Example 1 in which the lower photoconductive layer was removed and an upper photoconductive layer having a thickness of 15 μm was formed had a low charging ability and could not be put to practical use. Example 2 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. The dissolved liquid was poured into 10,000 parts of water to precipitate the phthalocyanine composition, which was then filtered, washed with water, and dried at 120°C under reduced pressure. The composition () obtained in this way was mixed with ε-type copper phthalocyanine (Lionol Blue manufactured by Toyo Ink Manufacturing Co., Ltd.).
Mix 30 parts to 100 parts of ER), and the following is Example 1
A mixture [] was prepared in the same manner as above, and a photoconductive composition was prepared based on the following formulation. Mixture [] 15 parts Acrylic resin (T- manufactured by Toyo Ink Mfg. Co., Ltd.)
coatPEX-7120 solid content 30% by weight) 30 parts silicone resin (Shin-Etsu Chemical Co., Ltd. KR211 solid content 70%)
Weight%) 5 parts Methyl ethyl ketone 30 parts Toluene 20 parts The above composition was milled in a porcelain ball mill for 48 hours, and 155 parts of zinc oxide (same as in Example 1) was added.
Furthermore, methyl ethyl ketone was added to adjust the viscosity.
The photoconductive composition obtained by kneading for 10 hours was coated on the same charge transfer layer as in Example 1 using a bar coater so that the dry film thickness was 5 μm, and the mixture was placed in an oven uniformly heated to 120°C. for 30 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 2.5 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.) 18 parts Dichloromethane 40 parts 1,2-dichloroethane 36 parts Light obtained by kneading the above composition in a paint shaker for 1 hour Using a bar coater, apply conductive paint to a thickness of 8 μm on a polyester film (Metal Me, manufactured by Toray Industries, Inc.) on which aluminum has been deposited, and place it in an oven uniformly heated to 120°C for 5 minutes to dry and charge. A moving layer was formed. Next, a photoconductive composition having the following formulation was manufactured. Composition of Example 1 [] 8 parts butyral resin (Eslec B manufactured by Sekisui Chemical Co., Ltd.)
13 parts ethyl alcohol 47 parts The above composition was kneaded for 1 hour in a paint shaker, then zinc oxide (SAZEX manufactured by Sakai Chemical Industry Co., Ltd.)
#2000) was added and kneaded for further 30 minutes to obtain a photoconductive composition. This photoconductive composition was coated onto the charge transfer layer using a bar coater to a dry film thickness of 7 μm, and dried at 80° 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 60% by weight, and its electrophotographic properties were measured in the same manner as in Example 1. The light sensitivity was 2.1 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, using this master plate, it was possible to obtain more than 3,000 good offset prints in the same manner as in Example 1.

[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, 2... First photoconductive layer, 3
...Second 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 first photoconductive layer has a phthalocyanine pigment dispersed in a binder resin as the lower layer, and the phthalocyanine pigment and zinc oxide are bound as the upper layer. 1. An offset master for semiconductor laser exposure, comprising a second photoconductive layer dispersed in an adhesive resin, wherein the ratio of zinc oxide in the second photoconductive layer is 60 to 85 percent by weight.