JP2704870B2 - Improved planographic plate material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lithographic printing plate material having a sulfonic acid group. More specifically, it is a lithographic printing plate material that is sensitive not only to low-output laser light in the visible and near-infrared regions but also to a thermal head such as a thermal printing device and does not require development and fixing. It relates to those with excellent stability. [Prior art] Conventionally, methods for obtaining a printing plate used for lithographic printing include:
(1) The so-called SP plate method, (2) the silver salt photographic method represented by the silver master method, and (3) the electrophotographic method represented by the electrofax method have already been developed and commercialized. However, these methods require a step of obtaining a printing plate after forming a latent image by exposure, developing and fixing, and the plate making process is complicated, and the plate making machine itself becomes large, and In addition, there are problems such as soiling of hands in handling the developer. In general, the method of laminating on an aluminum plate as a method of improving the dimensional stability of a plate material is not only expensive but also inferior in handling such as cutting and mounting of a plate. It was difficult to do. Further, the method of laminating on paper has a drawback that the dimensional stability and the printing durability are significantly reduced by the dampening solution used at the time of printing. The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, invented a method of manufacturing a lithographic printing plate that does not require processing steps such as development and fixing, and filed a patent application earlier (Japanese Patent Application Laid-Open See Japanese Patent Application Laid-Open No. Sho 60-102632 and Japanese Patent Application Laid-Open No. Sho 60-132760). [4 Problems] However, since those printing plate materials also required high energy density of light energy, practically, for example, a xenon flash lamp of several hundred watts or a laser oscillation having an output of several watts or more was used. In addition to the need to mount the machine, there was a point to be improved in that the dimensional stability was poor. The present invention significantly improves the plate making properties and dimensional stability of the above-described lithographic printing plate material having a hydrophilic sulfonic acid group, and is, for example, a 10-mW output He-Ne laser or a simple, such as a word processor. By performing printing operations using a compact thermal printer or thermal facsimile, not only can a lithographic printing plate be obtained,
It is an object of the present invention to provide an inexpensive plate material having excellent dimensional stability and handleability without being laminated on another base material. [Means for Solving the Problems] That is, the present invention provides a film or sheet mainly comprising a crosslinked aromatic polymer compound by a sulfonation reaction, wherein a sulfonic acid group is provided on the surface of the film or sheet. In the infrared absorption spectrum, the ratio of the absorbance of the band attributable to the sulfonic acid group near the wave number of 1050 to the strong band attributable to the sulfonic acid group near the wave number of 1200 is at least 0.6. It provides a lithographic printing plate material. Examples of the cross-linked aromatic polymer compound used in the present invention include monovinyl aromatic monomers such as styrene, α-methylstyrene, chloromethylstyrene, and vinylnaphthalene.
To 98 mol% and 2 to 50 mol% of a polyvinyl monomer. When the amount of the polyvinyl monomer is 2 mol% or less, a part of the reaction product is eluted in the sulfonation reaction. It is excluded because the plate material is deformed by fountain solution during printing and the dimensional stability is reduced. A preferred range is 10% or more. On the other hand, when the content is 50 mol% or more, the workability as a sheet is reduced, so that it is excluded. As the polyvinyl monomer used here, in addition to polyvinyl aromatic monomers such as divinylbenzene, divinylxylene, and trivinylbenzene, divinylpyridine,
Polyvinyl heterocyclic compounds such as trivinylpyridine, and polyvinyl aliphatic monomers such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate may also be used. Polymerization can be performed on these mixtures by a known polymerization method. As a simple method, a method of performing bulk polymerization in the presence of a polymerization initiator or a method of performing polymerization by heating in a suspended state is advantageous. If the polymerization is carried out in suspension, the amount of polymerization initiator is generally in the range from 0.05 to 3.0% by weight, based on the weight mixture. As the polymerization initiator, various polymerization initiators can be used. In general, oxides such as benzoyl peroxide and lauroyl peroxide and azo-based polymerization initiators such as azobisisobutyronitrile are useful. When performing suspension polymerization, the mixture of the above monomers is polymerized in the presence of a suitable dispersant, using water as a medium. After the completion of the polymerization reaction, the obtained copolymer is sufficiently washed with water, dried and pulverized. The fine powder thus obtained is mixed with dioctyl phthalate as a plasticizer and cyclohexanone as a dispersant, mixed with a polyvinyl chloride paste obtained by heating, kneaded using a roller, and manufactured while evaporating the dispersant appropriately. Film. In the case of a bulk polymer, for example, styrene is partially polymerized, or polystyrene dissolved in styrene is added with divinylbenzene, benzoyl peroxide and dibutyl phthalate to perform bulk polymerization. After completion of the reaction, the mass is cut into a thickness of 100 to 200 μ to obtain a sheet. The sheet thus obtained may be bonded to another substrate, for example, paper, glass cloth, glass paper, an aluminum plate, etc., and may be used as a composite material, but can be used as it is without bonding. There is no particular limitation on the method of sulfonation.For example, the film or sheet may be immersed in fuming sulfuric acid, or sulfuric anhydride may be used as it is or in chloroform, carbon tetrachloride, sulfuric anhydride such as ethylene dichloride, etc. On the other hand, it may be diluted with an organic solvent having relatively low activity.
Further, sulfuric anhydride may be sulfonated as an adduct with dimethylformamide or dioxane. Sulfonation conditions vary depending on the type of polymer used, but by performing the reaction using an oxidized sulfonating agent such as sulfuric anhydride, a structure having a strong band at a wave number of around 1200 in the infrared absorption spectrum is obtained. You can get things. This band indicates that at least a sulfonic acid group adjacent to the polyene structure having three conjugated double bonds has been formed, and it has been found that the sulfonic acid group exhibits photosensitivity or heat sensitivity. Completed the invention. That is, when the amount of the sulfonic acid group is generally 0.6 or more in terms of the absorbance ratio as compared with the amount of the sulfonic acid group which is attributed to the wave number of 1050, the photosensitive or heat-sensitive lithographic printing according to the present invention is excellent. Give plate material. Such excellent printing plate material of the present invention,
When an oxidized sulfonating agent is used, it can be obtained by appropriately selecting the sulfonating temperature and time. That is, in order to increase the ratio of sulfonic acid group formation adjacent to the polyene structure, it is desirable to lower the sulfonic acid temperature, and the reaction temperature is usually −
30-70 ° C, preferably 0-40 ° C. If the sulfonation temperature is 70 ° C. or higher, various side reactions are likely to occur, and are excluded. On the other hand, at -30 ° C or lower, when used in the form of sulfuric anhydride gas, the gas is liquefied and adheres to the inlet pipe wall, so that process abnormalities are likely to occur, and the generation rate of sulfonic acid groups adjacent to the polyene is reduced. It is removed because it is slow and economically unfavorable. On the other hand, the sulfonation time must be selected depending on the temperature, for example, 5 to 60 minutes at 0 ° C. and 1 to 30 at 40 ° C.
Minutes is a preferred range. In addition, other oxidizing low sulfonating agents generally used industrially, such as chlorosulfonic acid, phosphoric sulfonic acid, adducts of sulfuric anhydride with dimethylformamide or dioxane, etc., are adjacent to the polyene structure. Since the production amount of general sulfonic acid groups is superior to the production of sulfonic acid groups, it is difficult to increase the absorbance ratio to 0.6 or more, and special measures are required. When the amount of sulfonation is 5 × 10 ^-5 to 1 × 10 ^-1 meq / cm ² in terms of exchange equivalent, it gives the hydrophilicity necessary for forming a non-image portion in a lithographic printing plate, and generally gives a sulfonation reaction. As the amount of sulfonation increases with the progress, the hydrophilicity also improves, but the ratio of the absorbance is not always linear with the amount of sulfonation, so the optimal conditions must be selected for each polymer. . The amount of sulfonation is determined as follows. That is, a film whose surface is sulfonated (surface area: Mcm ² ) is immersed in a 1N aqueous solution of calcium chloride to make it equilibrium.
Titration with 0.1N aqueous sodium hydroxide solution (titer: f), neutralization value with indicator phenolphthalein (Xcc)
Is calculated by the following equation. Sulfonation amount (milli-equivalent / cm ² ) = (0.1 × f × x) / M The absorbance ratio referred to in the present invention is determined by using a baseline method generally adopted in the analysis of infrared absorption spectrum. That is, the wave number 1050 and attributed to the sulfonic acid group
Strong band around 1170 and wave number 1200 specified by the present invention
The ratio of the absorbance of the corresponding band is determined based on the baseline common to the nearby strong bands. The infrared absorption spectrum of the sulfonated compound can be measured by a reflection method (ATR method). It is known that non-photosensitive general sulfonic acid groups usually show two strong bands characteristic around the wave number of around 1050 and around the wave number of 1170, but further around the wave number of around 1200, preferably around the wave number of around 1200 to 1230. Said sulfonate having a photosensitive sulfonic acid group showing a comparable strong band, the absorbance of the band attributed to the photosensitive sulfonic acid group near 1200 wave number, attributed to the sulfonic acid group near 1050 wave number When the ratio of the band to the absorbance of the band is 0.6 or more, the lithographic printing plate material improved to have high sensitivity which is the object of the present invention is provided. It is generally difficult to obtain one having an absorbance ratio of 2.3 or more, and the absorbance of a sulfonate having the sensitivity required for plate making using a widely used thermal head is preferably 1.1 to 1.8. EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. Example 1 10 mol% of divinylbenzene and 90 mol% of styrene were copolymerized by a bulk polymerization method. This polymer was cut to a thickness of about 200 μm, and the plastic part was extracted with ethanol to remove B-
Four size sheets were prepared. The sheet was set in a dried glass container, and cooled from the outside so that the internal temperature was 0 to 5 ° C. On the other hand, sulfuric anhydride gas obtained by introducing a dry nitriding gas from the outside to a gas generator containing sulfuric anhydride is cooled from the outside so that the temperature becomes 0 to 5 ° C., and introduced into the reaction vessel. The reaction was performed for 15 minutes. After the completion of the reaction, the sheet was taken out of the container, washed with water, and dried. The sulfonated amount of the sheet was 3.2 × 10 ⁻³ meq / cm ² , and the absorbance ratio in the infrared absorption spectrum was 1.2. This sheet is attached to a rotating roll, and the peripheral speed of the roll is
A printing plate was produced by irradiating a beam focused at a beam diameter of 30 μm of a helium-neon laser (manufactured by NEC: GLG5400, output: 10 mw) at a setting of 70 cm / sec. When the thus prepared plate was attached to an offset printing machine and printing was performed, a clear image with a cotton width of 35 μ was obtained. The line widths and line intervals of the objects printed in the central part and the peripheral part were the same within the range of the measurement error. No image distortion was observed. Example 2 40 mol% of divinylbenzene and 60 mol% of vinyl toluene were subjected to suspension polymerization to obtain a fine powdery copolymer. After mixing this powder with dioctyl phthalate as a plasticizer and cyclohexanone as a dispersant, mix it with the polyvinyl chloride paste obtained by heating, knead with a roller heated to 60 to 70 ° C, and evaporate the dispersant appropriately. Thus, a sheet having a thickness of about 150 μ was obtained. The sheet was wound around a roll, and a sulfonation reaction was performed while introducing the sheet into a nitrogen gas atmosphere containing about 10% sulfuric anhydride gas. The reaction time averaged 20 minutes. After the completion of the reaction, the sheet was washed with water and air-dried. The sulfonated amount of this film was 6.1 × 10 ⁻³ meq / cm ² , and the absorbance ratio was 0.9. Next, the applicability of the fully automatic offset plate-making printing press (Ricoh Company: Ricoh Auto Printer AP 7000II) to the paper feeding process was examined. there were. In addition, this plate material was converted to a word processor (Sharp: WD-
530), and a printing operation was performed using a thermal head to prepare a printing plate. The applicability of the above-described auto printer to the printing process was examined. Met. Both the initial and about 5000th printed matter were clear, and no abnormalities such as deformation and distortion occurred in the characters and ruled lines at the periphery. Comparative Example 1 A commercially available biaxially stretched sheet of polystyrene (manufactured by Dai Nippon Printing Co., Ltd., having a thickness of about 200 μm) was subjected to sulfonation treatment under the same conditions as described in Example 1.
The resulting sulfonated sheet was deformed and could not be used as a plate material because a part of the sheet surface was eluted. [Effect of the Invention] As described above, a printing plate can be easily manufactured by using the lithographic printing plate material of the present invention.
Therefore, for example, when the reading and writing mechanism of the facsimile and the lithographic printing machine are connected via the printing plate material of the present invention, printing of high-quality characters (mass copying) as a fully automatic printing machine. Can be easier. In addition, a computer (workstation) having an editing / composing function and a lithographic printing press can be easily connected, so that a simple plate making / printing system can be provided. Furthermore, because of excellent dimensional stability, characters and ruled lines around the plate are not shifted or deformed and printed.
The present invention has many advantages, such as the ability to print in multiple colors.

Claims (1)

(57) [Claims] A film or sheet having a crosslinked aromatic polymer compound as a main material obtained by a sulfonation reaction, which has sulfonic acid groups added to the surface of the sheet. A lithographic printing plate material characterized in that the ratio of the absorbance of the strongly attributed band to the absorbance of the band attributed to the sulfonic acid group having a wave number of around 1050 is at least 0.6.