JPH08194317A - Method for forming image and exposure device for forming image - Google Patents

Abstract

PURPOSE: To provide a method for forming a high-quality image through scanning exposure with the use of a laser beam, especially, the laser beam of short wavelength by performing exposure by the use of a high-output laser device having oscillation range in an ultraviolet area, making a plate, and performing printing on a paper being a body to be transferred by the use of a printing machine. CONSTITUTION: The laser beam is used, and only light obtained by optically intercepting the light having oscillation line other than wavelengths of 320nm to 400nm being the photosensitive wavelength area of many photosensitive materials is extracted and used for image exposure. It is preferable to perform scanning exposure as the exposure, and it is desirable to perform scanning by a galvano mirror. In such a case, it is conceivable to use a scanning device other than the galvano mirror. A laser tube for consecutive oscillation or pulsative oscillation is good as a light source and argon ion laser is further suitable from the viewpoint of oscillation wavelength and intensity. The device is equipped with a device for making image data into dots, and the image data such as a line image, a character and a photograph passes through a raster image processor (arithmetic part) and is outputted to a laser device being an output part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and apparatus in the field of printing, and more specifically, it is a pre-sensitized lithographic printing plate requiring organic solvent, acid or alkali development. Pla
te, which is abbreviated as PS plate) and an exposure apparatus therefor. Specifically, the original plate is obtained by directly exposing digital image data by a laser exposure apparatus. The so-called CTP that does not require the use of film at all
(Computer to plate).

[0002]

2. Description of the Related Art In today's printing industry, PS plates as printing lithographic plates are easy to handle and cost-effective.
It has gained unwavering support in terms of performance and printability, etc., but in recent years, due to the shorter delivery times of printed materials, the silver complex salt diffusion transfer method is cheaper depending on the image quality of the printed materials, although it has lower abrasion resistance than the PS plate. The number of printed products by the (DTR method) is also increasing year by year. However, the silver complex salt diffusion transfer method (D
The drawbacks associated with lithographic printing plates made by the TR method) are, for example, that the resistance to mechanical abrasion is insufficient and the hydrophobic areas that carry the ink image gradually lose their ink receptivity, so Is to decrease. In addition, the hydrophilic areas gradually become hydrophobic and thus the non-image areas or the ground areas become smeared with ink. A printing plate that utilizes a metallic silver pattern formed by applying the DTR method as having ink acceptability is already known. For example, US Pat.
No. 837, No. 3721559, Japanese Patent Publication No. 48-1672
The contents described in Japanese Patent No. 5 and Japanese Patent Publication No. 48-30562 are in agreement. As described above, the printing plate by the DTR method often uses paper as a support, has a difficulty in registering, and may not be used unless the material price is very low. In addition, since the material of the DTR method uses silver as a photosensitive material, there is a problem in the disposal method, so management and operation are difficult.

Although the PS plate is more expensive than the DTR method, it has excellent abrasion resistance and ink acceptability, and is often used for producing printed matter requiring high quality. Generally, the composition of PS plate is “Light-Sensitive
Systems "Jaromir Kosar, John Wiley & Sons, Inc., pages 321 to 357 are suitable materials such as those described in British Patent 844039 and German Patent 10;
Many naphthoquinonediazide compounds as described in Japanese Patent No. 58845 are said to be preferable. Furthermore, Japanese Patent Publication No. 37-13109 and Japanese Patent Publication No. 37-1566.
5, Japanese Patent Publication No. 38-18015, Japanese Patent Publication No. 3818
-12083, Japanese Patent Publication No. 40-21093,
JP-B-45-27345, JP-B-51-1301
No. 3, etc., describes a photosensitive naphthoquinonediazide compound which is particularly suitable for the production of positive-working photosensitive printing lithographic plates. When these compounds are used as a photosensitive compound in a printing plate, they produce substantially good printing results, but they have a problem that the inherent sensitivity as a photosensitive compound is low.

It has also been proposed to increase the sensitivity by using a sensitizer as disclosed in US Pat. No. 4,307,173 and JP-A-58-11932. However, the development latitude is narrow and the sensitivity is appropriate. It becomes difficult to understand the development conditions,
In addition, there is a drawback that the stability deteriorates when stored for a long period of time. On the other hand, as a negative PS plate, a photopolymer system has long been considered useful, and German Patent 5967
No. 31 discloses a formaldehyde condensate of p-diazodiphenylamine and its derivative, US Pat. No. 27295.
No. 62 discloses 3-nitroanthranilic acid, British Patent 8
In Japanese Patent No. 59781, p-quinonediazide, which is a reaction product of a diazosulfonate and a diazonium salt, is described as being suitable, but it has a drawback that it is weak against a dark reaction as a printing lithographic plate.

Although the planographic printing plates have the above-mentioned drawbacks, they are used properly depending on the image quality finally obtained. In these cases, the PS plate had low sensitivity and the photosensitive wavelength range was limited to the near ultraviolet range. For example, as disclosed in U.S. Pat. No. 3,664,737, a method is disclosed in which a recording material having an ultraviolet light-sensitive layer, particularly a diazo light-sensitive layer, is directly written on an aluminum support by a laser to prepare a plate. It is necessary to prepare a laser tube with high output, and the cost of the device is high.
It was not practically applied because of the short tube life and the inability to expose a large size.

In the printing market, by combining a semiconductor laser and a high-sensitivity PS plate, it is possible to write image information directly on the plate without using an original film because of its advantages such as low price and small apparatus. -Turn-up plate) system is being shifted to. However, in many cases, since the material is highly sensitive and expensive, it is difficult to work in a bright room and the apparatus itself has to be made a dark room. Therefore, it is only used by some users. Ordinary PS
If you can write images directly on the plate, there is an advantage that you do not need to use film.

Therefore, a so-called ordinary inexpensive P which is not highly sensitive
It has been desired to develop a method and apparatus capable of directly writing an image on the S plate.

[0008]

The object of the present invention is to directly expose image data on a PS plate with an exposure machine using an ultraviolet laser, even if the PS plate has a low sensitivity. CTP
The present invention relates to a method and an apparatus for forming a plate capable of performing. The present invention has succeeded in satisfying quality requirements as CTP by creating means for exposing digital data on the plate and its exposure apparatus. Another object of the present invention is to provide a high quality image forming method by scanning exposure of a laser or the like, particularly a laser having a short wavelength.

As a result of earnest research, the inventors of the present invention exposed to light using a high-power laser device having an oscillation in the ultraviolet region to make a plate, and printed on a paper as a transfer target using a printing machine. As a result, it was confirmed that the printed image had sufficient image quality as a printed matter. According to this method, the greatest advantage is that the finally obtained image quality on the transferred material can be maintained. That is, even in the method in which an original mask is used as a means for exposing an image on an image forming material, an oscillation wavelength of 320 nm to 400 n is used as an image exposure light source according to the present invention.
It is significant that the image quality finally obtained is exactly the same even when exposed by a laser scanning device in the range of m. The image forming material considered to be optimal in this method does not need to change the basic physical properties such as sensitivity and photosensitivity wavelength, that is, it is troublesome to handle the material due to the effect of increasing the sensitivity of the material and the storage stability of the material. There is no such thing as sex.

[0010]

The exposure apparatus for image formation according to the present invention uses a laser to optically emit light other than the oscillation line from 320 nm to 400 nm which is the photosensitive wavelength range of many photosensitive materials. Only the blocked light is extracted and used for image exposure. The exposure is preferably performed by scanning exposure, and preferably scanning with a galvano mirror. In this case, a scanning device other than the galvanometer mirror may be used, and the scanning device is not limited to the device. The laser tube as a light source may be a continuous oscillation type or a pulse oscillation type, but from the viewpoint of oscillation wavelength, intensity, etc., an argon ion laser is used.
Is preferred. The oscillation line is not limited to one line, and may oscillate in essentially any wavelength range, and it can be used as a laser beam for irradiating the material to be exposed with light of many photosensitive materials. Wavelength range from 320nm to 40
It is preferably in the range of 0 nm. Also, the output of the laser tube is not suitable if it is too weak or too strong, but it passes through the optical lens system and the tube output is considerably attenuated.
The irradiated surface is in the range of 0.1 to 10 watts (W), the preferred range is 0.1 to 2 watts, more preferably 0.3.
To 1.5 watts.

The image forming exposure apparatus according to the present invention is provided with an apparatus for converting image data into halftone dots. Image data such as line drawings, characters and photographs passes through a raster image processor (RIP), and a laser which is an output engine.
Output to the device. No particular restrictions are placed on this RIP. Specifically, as shown in Fig. 1, image data of characters and photographs processed by an image processing computer is displayed.
The data is converted into a bit map by passing through the RIP which is a calculation unit, and is output by a laser exposure machine, a laser printer, or the like. The computer usable for the input system shown in FIG. 1 is not particularly limited as long as it can perform image processing. It is considered that the RIP, which is the arithmetic unit, does not have a binarizing mechanism, and a binarizing mechanism is necessary when outputting data from a laser exposure machine or the like. There is no particular limitation. As the output system, a laser exposure device, a laser printer, and various output devices can be used, but this is not particularly limited.

A polygon mirror is used as a means for scanning the laser beam, and the rotation speed of the polygon mirror is 3000 rpm or less, preferably 2300 to 400 r.
Exposure at pm is preferable, but this is not particularly limited. The plate that can be used in the present invention essentially comprises a support and a photosensitive layer. The support may be any material that is stable and can be a support, such as aluminum or paper. For example, cellulose acetate, polystyrene,
It is a film or sheet of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polypropylene or the like. An aluminum plate is particularly preferable.

As a hydrophilic lithographic plate material, for example, an image area (image) is usually formed on a thin plate having a thickness of 0.1 to 0.5 mm.
e area) and non-image area (non-image ar)
ea) is formed on the same surface, and the image area is (oleophilic) and hydrophobic (hydrophobic).
bic), ink acceptability (ink reception)
e), chemical properties such as water repellency and physical properties such as abrasion resistance and adhesion to plate material are required, and non-image area is hydrophilic (oleophyll).
ic), water retention, oleophobicity, water receptivity, ink repellency, and other chemical properties, as well as mechanical properties such as hardness, tensile strength, bending strength, abrasion resistance, and flexibility as a plate material. However, as the base material satisfying the above contents, aluminum, zinc, stainless steel, chrome, polyester,
There are papers and the like, and these materials may be used alone or in combination of several kinds.

As a lithographic printing plate material that can be hydrophilized, for example, in the case of an aluminum plate, a graining method and an anodizing method are generally used. Graining is performed by mechanical methods such as brush, wire, sandblast, and honing, and chemical methods such as chemical polishing and electrolytic polishing, in addition to ball polishing. In anodization, an aluminum plate for a lithographic plate is electrolytically polished or chemically polished, and then anodized in an electrolytic bath. This oxide layer (thickness 3 ~
5μ) are inactive, hard and countless small holes (hole diameter 200-750
It is composed of hexagonal cells with Å), has good adhesiveness and storability of the photosensitive layer, has excellent abrasion resistance, and is highly water-retentive, making it suitable as a plate surface and providing high abrasion resistance. To be

The photopolymer and quinonediazide-based materials for the photosensitive layer are preferably the above-mentioned materials and are not particularly limited to this example. Further, the photosensitive layer may contain additives such as a photopolymerization initiator and a thermal polymerization inhibitor. As the photopolymerization initiator, those having a good compatibility with the photopolymerizable compound and those having a photochemical inter-quantum cross quantum efficiency close to 1 are preferable, and examples thereof include benzophenone, benzoin ethyl ether, and benzyl dimethyl ketate. -Ale, azobisisobutyronitrile, 2-chlorothiozanzone, 2-
There are methylthiozanzone, 2-ethylthiozanzone, 2-isopropylthiozanzone, 4′-isopropyl-2-hydroxy-2-methylpropiophenone, and the like. Further, in order to enhance the photopolymerization initiation efficiency, A promoter may be used in combination. Aromatic-aliphatic tertiary amines and the like are known as this photopolymerization accelerator. For example, Michler's ketone, 4,4′-bisdiethylaminobenzophenone and the like are available. Accelerators, depending on the thing,
Since it may turn yellow, it is selected in consideration of the acceleration efficiency, yellowing, compatibility with the initiator, the energy of the actinic ray to be used, and the wavelength range.

Most of the thermal polymerization inhibitors are aromatic derivatives. What is important in selecting a thermal polymerization inhibitor is
The addition amount and compatibility are such that the radical generation for photopolymerization is not hindered and the radicals must be thermally suppressed. Commonly used so far are hydroquinone, p-methoxyphenol, t-butylcatechol, pyrogallol and the like.
However, the present invention is not controlled by combining other than aromatic compounds.

[0017]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. Example 1 A positive PS plate (VPS) manufactured by Fuji Photo Film Co., Ltd. was prepared. This PS plate was fixed on the exposure stage of a Genoptic laser exposing machine "DP40s" at a position where the photosensitive surface of the PS plate was irradiated with the laser, and a digital signal for a black plate of a positive image was fixed. Laser irradiation was performed. As the exposure conditions at this time, irradiation lasers 351.1 and 36 are used.
Take out two oscillation lines of 3.8 nm, laser power
The rotation speed was 1.2 W, the polygon mirror rotation speed was 500 rpm, the exposure time was about 150 seconds, and the exposure area was 580 mm × 600 mm. Furthermore, plates for cyan, magenta and yellow were prepared.

Next, the exposed black PS plate is treated with "DP
40s "taken out under fluorescent light, sodium silicate 5%
It was developed with the developer. Next, offset ink, TOYO-KINGTK-HI-PLUS L, which is normally used in Mitsubishi Heavy Industries, Ltd. Shiroku-bansai 4-color machine, Diamond IID-4
When printed using (manufactured by Toyo Ink Mfg. Co., Ltd.),
A complete offset print was obtained. Then, cyan, magenta and yellow plates were attached to the printing cylinder and printing was carried out to obtain a complete color print. Example 2 Exposure and printing were carried out under the conditions of Example 1 with the laser output at the time of exposure being 0.5, 1.2 W, and the rotation numbers of the hollygon mirror being 1000, 1500, 2000 rpm, and good images were obtained.

Example 3 Exposure, development and printing were carried out under the same conditions as in Example 1 except that only the oscillation line of 351.1 nm was taken out as a laser at the time of exposure, and a complete color printed matter was obtained. I was able to make Example 4 A complete color printed matter was produced by performing exposure, development and printing under the same conditions as in Example 1 except that only the oscillation line of 363.8 nm was taken out as the laser during exposure. I was able to.

Comparative Example 1 Exposure and development were carried out under the same conditions as in Example 1 except that the laser oscillation wavelength of the exposure machine was changed to 488.8 nm. The phenomenon of dirt was seen. Comparative Example 2 When exposure and development were performed under the same conditions as in Example 1 except that the laser oscillation wavelength of the exposure machine was changed to 514.5 nm, the decomposition reaction due to exposure was insufficient and the phenomenon of scumming occurred. It was observed.

Comparative Example 3 Exposure and development were carried out under the same conditions as in Example 1 except that the oscillation wavelength of the laser of the exposure machine was changed to 257.0 nm. The phenomenon of dirt was seen. Comparative Example 4 When exposure and development were performed under the same conditions as in Example 1 except that the laser oscillation wavelength of the exposure machine was changed to 244.0 nm, the decomposition reaction due to exposure was insufficient and the phenomenon of scumming occurred. It was observed.

[Brief description of drawings]

FIG. 1 is a schematic view of an image forming apparatus of the present invention.

Claims (5)

[Claims] 1. An image forming material for a lithographic printing plate, which comprises a support and a photosensitive layer formed on one surface of the support and is partially or wholly hydrophilic or capable of being hydrophilized. As the light source for image exposure for image exposure, the oscillation wavelength 32
An image forming method characterized by using laser light composed of at least one or more oscillation lines in the range of 0 nm to 400 nm. 2. The image forming method according to claim 1, wherein a continuous wave laser light having an output of 0.1 W or more is used as the laser light. 3. An image forming apparatus having means for laser exposing a digital signal as image data to the image forming material according to claim 1. 4. The image forming apparatus according to claim 1, wherein the number of revolutions of the polygon mirror as the means for scanning the laser light is 1000 revolutions per minute or less. 5. The laser exposing means has an oscillation wavelength of 320.
5. The image forming apparatus according to claim 3, further comprising an image exposure device that is a laser beam composed of at least one oscillation line in the range of nm to 400 nm.