JP2532244B2 - Method of manufacturing offset printing plates - Google Patents

Description

The present invention relates to a method for producing an offset printing plate material having improved photosensitivity and heat sensitivity. More specifically, the present invention relates to a method for manufacturing an offset printing plate material that is sensitive to laser light in an extremely low output visible and near-infrared region and does not require development and fixing processes.

[Conventional technology]

Conventionally, as a method for obtaining a printing plate used for offset printing, (1) a so-called PS plate method, (2) a silver salt photography method represented by a silver master method, and (3) an electrophotography represented by an electrofax method Laws have been developed and commercialized.

However, in these methods, after a latent image is formed by exposure, development, and fixing are performed, the plate making process for obtaining a printing plate is complicated, and the plate making machine itself becomes large, and
There was a problem that the handling of the developer became dirty.

Therefore, as a result of intensive studies to solve the above problems, the present inventors invented a method for producing an offset printing plate that does not require processing steps such as development and fixing, and applied for a patent in advance (Japanese Patent Laid-Open Publication No. Sho. 60-102632, JP-A-60-132760).

[Problems to be solved by the invention]

However, even those printing plates require high energy density of light energy, so practically, for example, a xenon flash lamp of several hundred watts or a laser oscillator having an output of several watts or more must be installed. There was a point to be improved.

INDUSTRIAL APPLICABILITY The present invention is to significantly improve the plate making property, particularly the sensitivity, of the above-mentioned plate material for offset printing having a hydrophilic sulfonic acid group, and is well sensitive to laser light in the visible and near infrared region with an output of several milliwatts. Moreover, it is an object of the present invention to realize a high-speed offset printing plate manufacturing method using a low-power laser beam, which does not require developing and fixing processing.

[Means for solving problems]

That is, the present invention provides a method for producing an offset printing plate material, which comprises treating the surface of a film containing a polyalkylene halide with a base in advance and then sulfonation.

The polyalkylene halide used in the present invention is selected from alkylene halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, propylene trifluoride, propylene hexafluoride and vinyl bromide. Polymerization or copolymerization of one or two or more monomers, or those obtained by copolymerizing with at least one of other monomers such as ethylene, propylene, butene-1, and hexene-1 It is the main material.

Examples of the base include high-concentration caustic soda of 5 to 40%, inorganic base such as caustic potash, tertiary amines such as triethylamine, tri-n-propylamine and tri-n-butylamine, and trimethylbenzylammonium hydroxide. Use the one dissolved in a polar solvent such as water, methanol, ethanol or dimethylformamide. The processing conditions vary depending on the type of polymer compound used, but generally the film becomes colored as the processing time becomes longer, so at least a light brown color is used as a guide.

The film subjected to the above treatment is thoroughly washed with water and dried in air. The visible absorption spectra of these films can be measured using the reflection method, which uses 450 nm.
It is preferable to have strong absorption at the above wavelengths. When a film having a strong absorption at a wavelength of 400 nm or less is further sulfonated, it is excluded because the sensitivity when forming an image as a plate material is low.

These films may be laminated with other base materials such as paper, glass cloth, glass paper, and aluminum plates to be used as a composite material.

The sulfonation method is not particularly limited, and for example, the above-mentioned film which has been subjected to a predetermined treatment may be immersed in fuming sulfuric acid, or sulfuric acid anhydride as it is, or chloroform, carbon tetrachloride, ethylene dichloride, etc. It may be used after diluting it with an organic solvent having a relatively low activity with respect to sulfuric anhydride. Further, sulfuric acid anhydride may be sulfonated as an adduct with dimethylformamide, dioxane or the like.

The sulfonation conditions vary depending on the type of polymer used and the degree of treatment, but the sulfonation amount is 5 × 10 ^-5 to 1 × 10 ^-1 meq / cm ² in terms of exchange equivalent, The contact angle of water with water is 40 degrees or less, preferably 30 degrees or less.

When the degree of sulfonation is 5 × 10 ⁻⁵ meq / cm ² or less, the contact angle becomes 40 ° or more, which is not preferable.

On the other hand, when the sulfonation amount is 1 × 10 ^-1 meq / cm ² or more, the contact angle is 5 degrees or less, and there is no particular problem with the performance as a plate material, but it is economically unfavorable and is therefore excluded.

The sulfonation amount is obtained as follows. That is, a film whose surface is sulfonated (surface area Mcm ² ) is immersed in a 1N calcium chloride aqueous solution to reach an equilibrium state, and hydrogen chloride generated in the aqueous solution is dissolved in a 0.1N sodium hydroxide aqueous solution (titer: f ), The neutralization value (Xcc) with the indicator phenolphthalein is obtained, and calculated by the following formula.

Amount of sulfonation (milliequivalent / cm ² ) = (0.1 × f × x) / M [Examples] The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Example 1 A commercially available polyvinyl chloride film (manufactured by Sumitomo Bakelite Co., Ltd .; Sumilite VSS, water absorption rate of 0.1% or less) was held in a stainless steel frame, and then put in a 40% caustic soda aqueous solution.
After heat treatment at 4 ° C for 4 hours to obtain a brown film, the film was washed with water and dried for 3 hours in a vacuum dryer installed at 60 ° C. Next, in a 4-neck separable flask equipped with an anhydrous sulfuric acid gas inlet tube, set the stainless steel frame holding the polyvinyl chloride film treated with caustic soda, cool the inside of the flask with nitrogen gas, and After reducing the pressure to 350 mm of mercury column while maintaining the temperature at 0 to 5 ° C., the exhaust pipe was closed and sulfuric acid anhydride was introduced until the column reached 450 mm of mercury column, and the mixture was kept for 10 minutes to carry out the sulfonation reaction. After completion of the reaction, the stainless steel frame was taken out, washed with water, and then air-dried in a dark place.

The sulfonation amount of the film was 4.1 × 10 ⁻³ meq / cm ^2.
In the infrared absorption spectrum, a broad and strong band was shown near 500 nm. The contact angle on the surface of the film was measured by a water-liquid method, and it was 10 degrees or less.

The film thus obtained was attached to a rotating roll, the rotation speed of the roll was set to 15 m / sec, and the beam diameter of the helium-neon laser (NEC: GLG5400, output 10 mw) was focused to 20 μ. And scanned.

The plate thus produced was attached to an offset printing machine (DP-3100 manufactured by Duplo Co., Ltd.) for printing, and a clear image line having a line width of about 21 μ was obtained.

Example 2 A commercially available fluororesin film (manufactured by Nitto Denki Kogyo; No. 450) was treated in a 40% methanol solution of trimethylbenzylammonium hydroxide at 60 ° C. for 1 hour and then washed with water, Air dried. Then, sulfonation treatment was performed in 20% fuming sulfuric acid for 2 hours. After further washing with water, neutralization with 1N caustic soda, and air drying in a dark place.

The absorption spectrum of the film thus obtained is 550 nm.
A wide band was shown in the vicinity.

The sulfonation amount was 2.6 × 10 ⁻³ meq / cm ² , and the contact angle with water was 5 ° or less.

Attach this film to a rotating roll and rotate it at a speed of 15 m / sec while using a semiconductor laser (LT0
27MD / MF, output 10mw) was focused and scanned to a diameter of 20μ using an optical lens.

When the plate thus prepared was set in an offset printing machine and printing was performed, a clear image line of 22μ was obtained.

(Effect of the invention) The plate material for offset printing produced by the method of the present invention is a laser beam having an output of several milliwatts and is sensitive to visible or near-infrared region. -By forming an image using a Ne laser or a semiconductor laser, a high resolution offset printing plate can be manufactured in an extremely short time.

Further, since the printing plate material manufactured by the present invention can form an image at high speed by using a laser beam having an extremely low output, it can be applied to a punching portion of a computer and does not require a negative film. A simple automatic plate-making process that allows you to obtain high-quality printed matter directly by plate-making.
It is possible to provide a printing system.

Claims (1)

(57) [Claims] 1. A method for producing an offset printing plate material, which comprises subjecting a surface of a film containing a polyalkylene halide to a treatment with a base in advance and then sulfonation.