JP2001071656A - Image forming material, original plate for lithographic printing, image forming method, and method of making lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming material, with which a drawing can be possible with laser light, the degree of polar change in which is nearly equal to that developed in a PS plate and which can be employed as an original plate for lithographic printing, by providing a titanium nitride layer on the surface of the material or of the original plate. SOLUTION: By providing a titanium nitride layer on the surface thereof, an image forming material is obtained. In order to form an image on the surface of the image forming material, laser light having a wavelength ranging from 800 to 1,200 nm is applied to the titanium nitride layer of the image forming material so as to form the black image. Further, by providing a titanium nitride layer on the surface thereof, an original plate for lithographic printing is obtained. Similarly, in order to process a lithographic printing plate, laser light having a wavelength ranging from 800 to 1,200 nm is applied to the titanium nitride layer of the original plate for lithographic printing. By employing the image forming material, the polar change due to the application of the laser is large, resulting in obtaining an original plate for lithographic printing, in which a few scumming develops even during printing. In addition, the image forming material can also be employed in uses such as a nameplate, a decorative sheet, a recording material or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming material having a titanium nitride layer on the surface and a method for forming an image by irradiating a laser to the titanium nitride layer of the material. The present invention further relates to a lithographic printing original plate having a titanium nitride layer on the surface and a method of making a lithographic printing plate by irradiating a laser to the titanium nitride layer of the lithographic printing original plate.

[0002]

2. Description of the Related Art Lithographic printing techniques are based on the immiscibility of oil and water, wherein an oily material or ink is selectively retained by an image area. After wetting the surface of a properly prepared plate with water and applying the printing ink, the non-image areas retain and repel water while the image areas receive and repel ink. . Therefore, when the ink is brought into direct contact with the surface to be printed or indirectly through an intermediate called a blanket, the ink on the image area is transferred and printing is performed.

A general lithographic printing plate needs to be developed with a developing solution after imagewise exposure. The developer removes the non-image area of the image forming layer to expose the roughened and hydrophilic support surface. The developer is a typical aqueous alkaline aqueous solution and may contain large amounts of organic solvents.
Therefore, development has long been an important concern in the printing field, as not only the complexity of the working steps, but also the need to dispose of large amounts of spent alkaline developer waste after development. In recent years, the problem of alkali developing waste has been particularly noticed from the standpoint of environmental protection, and methods for reducing the amount of waste as much as possible and measures for reducing alkalinity have been proposed.
The fundamental solution has not been reached.

Further, Japanese Patent Application Laid-Open No. Hei 9-169098 proposes a system in which a member using ZrO ₂ ceramic itself converts the polarity by laser light. The same inventors have proposed in JP-A-10-309877 and JP-A-10-301271 a tape which can be used as a plate cylinder or a printing plate made of the same ZrO ₂ material. In these systems, the material of the plate cylinder itself has sensitivity to laser, and is compatible with drawing (oleophilicity) and erasing (hydrophilizing) at different wavelengths. It can be done only by irradiation.

[0005]

However, the problem with the materials proposed in the prior art is that the degree of polarity change is very small. When the polarity change is small, if the surface is contaminated with any time signature, there is a high possibility that the ink will adhere to the non-image portion and become dirty when printing is performed. In order to use it as a member for lithographic printing (original plate), it is desirable that there is a difference in the polarity similar to that of the PS plate as currently used. Accordingly, an object of the present invention is to provide an image forming material which can be drawn by a laser beam, has a degree of polarity change similar to that of a PS plate, and can be used as a lithographic printing original plate. Another object of the present invention is to provide a method for forming an image on the image forming material. Another object of the present invention is to provide a lithographic printing original plate that can be drawn by a laser beam and has a degree of polarity change similar to that of a PS plate. Another object of the present invention is to provide a method for making a lithographic printing plate, in which the lithographic printing original plate is irradiated with a laser beam.

[0006]

According to the present invention, there are provided an image forming material, a lithographic printing original plate, an image forming method, and a lithographic printing plate making method having the following constitutions, thereby achieving the above object of the present invention. Is done. (1) An image forming material having a titanium nitride layer on the surface. (2) Irradiating the titanium nitride layer of the image forming material according to (1) with a laser beam having a wavelength of 800 to 1200 nm,
An image forming method on an image forming material surface, wherein a black image is formed. (3) A lithographic printing plate precursor having a titanium nitride layer on the surface. (4) A method of making a lithographic printing plate, comprising irradiating the titanium nitride layer of the lithographic printing plate precursor according to (3) with a laser beam having a wavelength of 800 to 1200 nm.

By using the image forming material of the present invention, it is possible to obtain a lithographic printing original plate having a very large change in polarity due to laser irradiation and having little stains even in printing techniques. Specifically, a lithographic printing plate precursor having a titanium nitride layer on the surface and capable of directly forming an image by laser is obtained. Further, by irradiating the image forming material of the present invention with a laser having a near infrared wavelength, it is possible to simultaneously form a black image and make the surface hydrophilic. Therefore, the image forming material of the present invention can be used not only as a lithographic printing plate precursor but also for applications such as a nameplate, a decorative plate or a recording material. In the field of lithographic printing processes, the use of titanium nitride as a material that can be directly laser imaged in "printing member" applications is not disclosed, and the present invention provides a significant advance in the lithographic printing art. Hereinafter, the present invention will be described in detail.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The image forming material of the present invention has a titanium nitride (TiN) layer, preferably 10 μm thick, on its surface.
As described above, the titanium nitride layer more preferably has a thickness of 10 to 20 μm. It is well known that titanium nitride is formed into a metal film by CVD or the like rather than a sintered body and used as a tool, or the surface of Ti surface modified by implanting nitrogen into the surface is well known. And it is well known that the surfaces so produced, when smooth, present a beautiful golden color. In the present invention, such a titanium nitride layer is desirably formed by sintering. However, when the sintering is insufficient or the solid obtained by the reaction sintering method has a very porous structure,
Water may be absorbed from the surface due to the voids. Such surfaces are unsuitable for image forming material applications.

In order to obtain a flexible image forming material, it can be obtained by applying slurry-like titanium nitride on a base metal by a method known as a doctor blade method and sintering. A lithographic printing plate precursor having a titanium nitride layer on the surface can be obtained, for example, by forming a titanium nitride film on the aluminum surface by thermal spraying. The thickness of the titanium nitride layer of the lithographic printing plate precursor is preferably 10 μm or more, and more preferably 10 to 20 μm.

As long as the titanium nitride layer is obtained, there is no particular limitation on the method of forming the titanium nitride layer. However, it is preferable to obtain a black image indicating that the layer has been rendered hydrophilic by laser irradiation. However, it is not advisable to form a titanium nitride layer by a sputtering film forming method, a CVD method, or the like.

The titanium nitride sintered body used in the present invention can be efficiently converted from lipophilic to hydrophilic by irradiation with active light having a near-infrared wavelength. The laser wavelength used for drawing an image has a wavelength range of 800 to 1200 μm. In particular, 1064 nm among lasers used for drawing
Nd-YAG laser having the following wavelength is preferred. In particular, a system equipped with a Q switch, which is optically pumped by a krypton arc lamp by pulse oscillation and which can give a high-energy pulse in a short time is preferable.

When an image is formed on the surface of the titanium nitride layer using these lasers, it is preferable to irradiate a laser having a peak output of 1000 W, preferably 2000 W. The preferred intensity of the irradiating light varies depending on the target level of discrimination between images and non-images since the polarity (contact angle) also changes depending on the amount of irradiating light. 0.05 to 100 joule / cm
² , preferably 0.5 to 10 joule / cm ² , more preferably 1 to 5 joule / cm ² .

When these lasers are irradiated, the irradiated parts are blackened and the image parts can be observed with the naked eye.
At the same time, the surface becomes significantly hydrophilic by irradiation. In printing using this system, the laser irradiated surface acts as a non-image portion.

The "change between lipophilicity and hydrophilicity upon irradiation with laser light" which is the basis of the present invention is extremely remarkable. The greater the difference between the hydrophilicity and the lipophilicity of the image area and the non-image area, the more remarkable the discriminating effect, the sharper the printed surface, and the greater the printing durability. The difference between hydrophilicity and lipophilicity can be represented by a contact angle with a water droplet. As the hydrophilicity increases, the water droplets spread and the contact angle decreases,
Conversely, when water droplets are repelled (water repellency, that is, lipophilicity), the contact angle increases. Therefore, in the lithographic printing plate precursor having the titanium nitride surface layer according to the present invention, the contact angle of the portion that has been irradiated with the laser light changes rapidly, and an ink holding portion and a water holding portion are formed on the plate surface on the image, The ink is transferred to the printing surface by contact with a receiving sheet such as paper.

[0015] Japanese Patent Application Laid-Open No. 9-169 described above as a prior art.
While the degree of change in polarity of zirconia (ZrO ₂ ) described in JP-A-09898 is insufficient, the change in polarity on the surface of the titanium nitride layer according to the present invention is very large, similar to that of a conventional lithographic printing original plate. It is possible to obtain a surface having a difference in hydrophilicity and lipophilicity between the image area and the non-image area.

After performing imagewise exposure on the titanium nitride surface layer, this original plate is subjected to a lithographic printing process as it is as a lithographic printing original plate without development processing. Therefore, it has many advantages in its simplicity as compared with the known lithographic printing method. That is, as described above, the chemical treatment with the alkali developing solution is unnecessary, the wiping and brushing operations involved are not required, and the environmental load due to the discharge of the developing waste is not involved. Since the surface of the lithographic printing plate precursor obtained as described above has a sufficiently image-like change in polarity, it has been conventionally subjected to a hydrophilic treatment or a lipophilic treatment (a lipophilization treatment). ) Is basically unnecessary, but if desired, washing water, a rinsing solution containing a surfactant,
Post-treatment may be performed with a desensitizing solution containing gum arabic or a starch derivative. However, at the time of the sensitization treatment, the conventional processing solution basically performs the sensitization action on the organic photoreceptor component, and therefore, the effect cannot be expected even if it is used as it is.

The image forming material of the present invention capable of directly forming an image with a laser may be in any form when used as a lithographic printing original plate. It is also available in a sleeve-like form. However, since care must be taken in handling, it is preferable to use a metal substrate provided with a titanium nitride layer. All substrates used are dimensionally stable and of sufficient strength, including, for example, stainless steel, nickel, brass, aluminum or other metals or alloys. When a titanium nitride layer having a desired film thickness is provided on the above-described substrate, a method such as thermal spraying can be used. In such a case, it is necessary to select the substrate in consideration of the high temperature. is there. A structure in which a titanium nitride layer is provided on a plate-shaped base metal may be processed into a sleeve shape and used.

In the printing method using the image forming material and the lithographic printing plate of the present invention, a laser light source used for image formation on the surface, a control means for operating the laser, a fountain solution supply means, and a fountain solution are applied to the printing surface. The lithographic printing system includes means for supplying lithographic printing ink and means for transferring the lithographic printing ink to a printing surface.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited by the examples.

Example 1 (Titanium Nitride Sintered Body) A plate-like material was prepared by pressing a TiN powder (made by Nippon Shinmetal) and then sintering it. The surface of the obtained plate-shaped material was irradiated (exposed) like a square image using a YAG laser beam under the following conditions. Apparatus: NEC output: average output 2 W peak output 8.3 kW frequency: 2 kHz pulse irradiation time: 0.12 μsec scanning speed: 50 mm / sec The irradiated surface turned black. The contact angle between the YAG laser irradiated part and the non-irradiated part was measured by dropping a water drop on the surface in the atmosphere. As a result, it was confirmed that the irradiated portion was expanded and wetted with respect to the non-irradiated portion. (Unirradiated area 37 ^O → irradiated area 0 ^O ) Further, when a simple print test was performed using this surface, it was confirmed that the ink was on and off, and a good printed image could be obtained. In addition, printability was implemented by the method described below. (Method of printing test) Pure water was supplied onto the substrate using a sponge. A well-kneaded ink was supplied from above with a roller. Thereafter, the ink image was transferred to a roller to which a blanket was attached, and further the image was transferred from the blanket to paper for printing.

Example 2 (Titanium Nitride Film) Titanium nitride films having a film thickness of 10 μm and 50 μm were formed by thermal spraying. When laser irradiation was performed in the same manner as in Example 1, a black hydrophilic image could be obtained.

Comparative Example 1 (Titanium Oxide Sintered Body) A TiO ₂ powder sample (manufactured by Wako Pure Chemical Industries, Ltd.) was press-molded and sintered to produce a plate-like material. The surface of the obtained plate-shaped material was irradiated with laser under the same conditions as in Example 1. Although the irradiated surface turned black, the contact angle between the YAG laser irradiated part and the non-irradiated part was measured by dropping a water droplet on the surface in the atmosphere. The contact angle of the irradiated portion was originally as small as 26 ^O, and a simple print test was performed. As a result, the printed image could not be obtained because the ink was not turned on and off.

[0023]

The image-forming material of the present invention having a titanium nitride layer on its surface can be drawn by laser light, and its polarity change is comparable to that of PS plates, and can be used as a lithographic printing original plate. . According to the image forming method of the present invention, an image is drawn only by irradiating the image forming material with a laser. The lithographic printing plate precursor having a titanium nitride layer on the surface of the present invention can be drawn by laser light. The lithographic printing original plate of the present invention drawn by a laser beam has the same degree of polarity change as the PS plate, and can be used for printing as it is. As described above, according to the present invention, it is possible to obtain a printing original plate capable of forming an image without any treatment with a chemical liquid, and to realize an environment-friendly printing system that is free from waste liquid and the like. Further, the lithographic printing plate precursor of the present invention has a high so-called plate inspection because the laser-irradiated portion is clearly blackened. If an image is directly formed on the lithographic printing original plate attached to the plate cylinder of the printing press on the press, labor such as registration marks registration can be omitted, and printing can be shortened in time and labor can be saved.
In addition, when used for a member other than a printing member, so-called weather resistance is greatly improved by using an inorganic material such as titanium nitride as compared with an organic material. Therefore, when used for a nameplate or the like used outdoors, it is expected that deterioration over time such as fading will be small. Furthermore, titanium nitride is originally a material having high hardness used for tools and the like, and can withstand mechanical damage. In addition, since images can be directly formed by laser irradiation, it is possible to completely respond to the serial number such as the product number at the same time as software, and greatly reduce the trouble of entering only the number separately. Becomes possible.

Continued on front page F-term (reference) 2H025 AA00 AB03 AC08 AD01 AD03 BB03 BH03 EA03 FA03 2H084 AA14 AE05 BB01 CC05 2H096 AA07 AA08 BA13 BA20 EA04 2H111 HA14 HA21 HA35 2H114 AA04 AA24 AA27 GA01 BA01 DA05 DA

Claims (4)

[Claims] 1. An image-forming material having a titanium nitride layer on the surface. 2. A method for forming an image on the surface of an image forming material, comprising irradiating the titanium nitride layer of the image forming material according to claim 1 with a laser beam having a wavelength of 800 to 1200 nm to form an image. . 3. A lithographic printing plate precursor comprising a titanium nitride layer on the surface. 4. A method of making a lithographic printing plate, comprising irradiating the titanium nitride layer of the lithographic printing plate precursor according to claim 3 with a laser beam having a wavelength of 800 to 1200 nm.