JP3949278B2 - Photomask film for printing plate making - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photomask film for printing plate making used for producing a printing plate used for printing such as offset printing, flexographic printing, and screen printing.
[0002]
[Prior art]
Conventionally, offset printing using a PS plate, flexographic printing using a resin relief plate, and screen printing using a photosensitive resin use a lith film using a silver salt as a photosensitive agent. In either case, after setting the silver salt film on the surface of the photosensitive layer of the plate material, the photosensitive layer is irradiated with light or ultraviolet rays through the film, and the photosensitive layer portion irradiated with light or ultraviolet rays by photochemical reaction or the like is solubilized or The principle of forming an image line portion corresponding to an image on the plate material is used by insolubilizing and then developing the photosensitive layer to remove the soluble portion.
[0003]
However, when a lith film is used, it is necessary to treat the developer with a waste liquid. Further, since the price of the development / printing / fixing system and the price of the lith film itself are very expensive, improvement has been demanded.
[0004]
On the other hand, in recent years, the development of electronic technology has been remarkable, and high-functional models of computers have become available at low prices and have become available in various fields. Similarly, output drawing machines such as computers and recording devices have also made significant technological improvements, and are promising for use in CAD applications utilizing high-definition printout performance. There is a possibility.
[0005]
Drawing machines are classified into several methods according to the image forming principle. As a substitute film for the lith film, for example, a polyester film such as PET is used as a base material, and each image forming method is provided on the surface of the base material. A transparent film that has been subjected to special special treatment may be used. However, since it is intended for plate making, it is necessary to have excellent dimensional stability of the base film as well as the resolution, which is a major factor in selecting the drawing method.
[0006]
In other words, in thermal printing devices and electrophotographic systems, when an image is formed on a film, the heat of the head is naturally continuously applied to the film, and the film is stretched or deformed particularly when printing solid. The accuracy required from the plate making use cannot be obtained.
[0007]
In this respect, the ink jet method does not cause such a problem. However, a plastic film used as a transparent film is usually hydrophobic, whereas a hydrophilic film is indispensable from the characteristics of the ink used. Furthermore, it is necessary to use a recording sheet that has excellent ink wettability and absorbability, and does not generate stains due to ink flow, bleeding of the print screen under high humidity, or stickiness of the screen surface.
[0008]
Furthermore, ultraviolet rays are used to expose the photoreceptor in order to produce a high resolution plate. Therefore, the drawn and ink-filled portions are required to have a light-shielding property against ultraviolet rays, and the ink-free film portions are required to have transparency to ultraviolet rays, and the ink and film having such characteristics are combined. It will be necessary.
[0009]
On the other hand, in order to avoid the complication of using a plate-making film for plate-making, direct plate-making is also proposed in which an image is directly formed on a plate material using a drawing apparatus.
[0010]
As one of the direct plate making systems, for example, a laser plate making system is conventionally known. In this system, the surface of a plate material such as a PS plate or an electrophotographic plate is scanned with a laser beam that is turned on / off based on digital image information, and a chemical change or a physical change of a portion irradiated with the laser beam is performed. An image portion corresponding to the image information is formed on the plate material. However, in such a laser plate making system, a laser device that generates a laser beam, a complex optical system that drives a single laser beam output from the laser device based on image information, and guides it to the surface of the plate material, drive Since a system or scanning system is required, the apparatus or system becomes large and expensive. Also, various plates can be made by this system. For example, when a plate material using a silver salt as a photosensitive material is used, there is a problem that the plate material is expensive although the sensitivity and resolution are high. Further, when a laser plate making system is applied to an electrophotographic system for forming a toner image on a photoreceptor, the process is complicated and the resolution is not sufficient. The laser plate-making system using a photopolymerization printing plate as the plate material is excellent in terms of resolution and cost, but the sensitivity is not sufficient so that a high-power laser is required, resulting in an uneconomic system. is there.
[0011]
As a direct plate making system other than using a laser, a method using a thermal drawing apparatus such as a thermal head and an ink drawing apparatus has also been proposed. However, in the thermal plate making system, the heat transferred from the thermal head to the thermal recording surface is also transferred to the part not in contact with the surrounding thermal head, and this part is also changed. Therefore, there is a problem that the boundary is not sharp and the resolution is limited. In addition, the ink jet plate making system does not have a problem like the heat sensitive plate making system, but there is a problem that complexity is increased, for example, it is necessary to select an optimal ink depending on the type of photosensitive resin on the plate material.
[0012]
In textile printing and the like, a plate is usually used for the pattern portion, but a method of directly drawing on a fabric by an ink jet method or the like has been developed. However, productivity is inferior to the method of printing after making a plate, and the plate making method is still superior for mass production.
[0013]
[Problems to be solved by the invention]
As described above, the conventional plate making method is disadvantageous in that it is expensive, is insufficient in terms of resolution and dimensional stability of the plate to be produced, is complicated in operation, or is inferior in mass productivity. I had.
[0014]
The present invention provides a photomask film for printing plate making which eliminates the above-mentioned conventional drawbacks, has an image formed on a plate making film which is inexpensive, has sufficient accuracy and dimensional stability, and is excellent in mass productivity. For the purpose.
[0015]
[Means for Solving the Problems]
The photomask film for printing plate making of the present invention has a transparent substrate and an ink receiving layer containing alumina hydrate as an active ingredient provided on the substrate, and an ink jet system on the ink receiving layer A photomask film for printing plate making having an image drawn by the above , wherein the image contains a water-soluble azo dye selected from yellow mono- or disazo dyes having an absorption peak in light having a wavelength of 350 to 420 nm It consists of an image with ink .
[0016]
Here, the alumina hydrate can be pseudo boehmite.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The film for plate making of the present invention is provided with a recording film as an ink receiver on a transparent substrate, and this recording film is composed of alumina hydrate as an active ingredient.
[0018]
As the transparent substrate, for example, a film made of polyethylene terephthalate, polyvinyl chloride, diacetate, triacetate, acrylic polymer, cellophane, celluloid, polycarbonate or the like is preferably used.
[0019]
The thickness of the transparent substrate is preferably 25 to 300 μm, and particularly preferably 50 to 200 μm. If the thickness of the transparent substrate is 25 μm or more, the transportability in the machine during recording of images and the like and handling during plate making are good, and if it is 300 μm or less, it is advantageous in terms of cost.
[0020]
Conventional recording films for inkjet use have been made of inorganic fine particles such as talc and silica, or polymers having a property called hydrophilicity such as water solubility or water absorption. Talc is poor in ink absorbency and can only be used for low-quality printing.Although silica and hydrophilic polymers are ink-absorbing, they carry a large amount of solvent together with the dyes that make up the ink, so a clear printed image It was difficult to get.
[0021]
The plate-making film needs to be coated with ink completely without any gaps, so that the solid portions do not become so-called streaks. Therefore, a large amount of ink is applied, but when a large amount of ink is applied, a so-called beading phenomenon occurs, and a large amount of ink is unevenly distributed on the surface of the ink receiving layer (recording film), resulting in density unevenness. In addition, since a large amount of ink is deposited on the recording film, when the film is stacked after printing, the ink receiving layer (recording film) that has absorbed a large amount of the ink dissolves and swells and develops an adhesive property that adheres to each other. That is, a so-called blocking phenomenon is likely to occur. Therefore, the sufficient absorption capability of the recording film and the adsorption capability capable of sufficiently supporting the dye in the ink are particularly important.
[0022]
The film for plate making of the present invention uses alumina sol (alumina hydrate) which is used in many fields such as textile industry, ceramic and refractory industry, cosmetics, petrochemical (catalyst support), and ink absorbency. And a recording film excellent in adsorption ability.
[0023]
As the alumina hydrate used in the present invention, one having an adsorption capacity of 20 to 100 mg / g is particularly preferable. This is because an alumina hydrate having an adsorption capacity in this range can provide sufficient color development and resolution. Here, “adsorption capacity” is expressed as the amount of solid matter of the dye adsorbed in the powder (mg / g). The amount of solid matter of the dye is a powder having an average particle diameter of 15 μm in 100 cc of water at room temperature. It is calculated | required from the quantity of the dye aqueous solution dripped by adding 1g and stirring the aqueous solution containing 2 weight% dye at a rate of 1 cc / min, and stirring the liquid.
[0024]
The alumina hydrate used in the present invention has pores, and the total volume of pores having a radius of 40 angstroms or more and 100 angstroms or less is 0.1 cc / g or more and 0.4 cc / g or less. preferable. If it is 0.1 cc / g or more, the dye absorbency is good, and in the case of solid coating, printing unevenness does not occur and excellent plate making can be performed, and if it is 0.4 cc / g or less, the transparency of the plate making film is not impaired. When a plate is produced by ultraviolet rays, sufficient contrast can be obtained between the printed portion and the non-printed portion. The pore size distribution is measured using "Omnisorb 100" manufactured by Omicron Technology.
[0025]
The alumina hydrate used in the present invention includes various types. For example, it is an aggregate of colloidal boehmite particles, which is produced by hydrolysis of aluminum alkoxide, and has a uniform particle diameter and a pore structure. The use of controlled pseudo boehmite is particularly preferred in terms of color development. That is, by using pseudoboehmite as an ink receiver, a sufficient color forming effect can be obtained with a pore volume that sufficiently adsorbs the dye in the ink and does not impair the transparency.
[0026]
In the present invention, for example, a mixed slurry of alumina hydrate and binder is prepared, and this mixed slurry is applied on a transparent substrate by various coaters and dried to prepare a plate-making film. As the binder, starch, PVA, cellulose, polyalkylene oxide and the like can be used. The amount of the binder used is preferably 10 to 100% by weight of the alumina hydrate.
[0027]
The thickness of the layer containing alumina hydrate varies depending on the amount of ink to be used, but is generally preferably in the range of 1 to 100 μm, particularly preferably 3 to 50 μm. If the thickness is 1 μm or more, the ink absorbability and dye adsorption performance are excellent, and if it is 100 μm or less, the transparency is not impaired and the mechanical strength of the ink receiving layer (recording film) is not lowered.
[0028]
【Example】
Pseudoboehmite sol AS-3 (manufactured by Catalyst Kasei Co., Ltd.) having an adsorption capacity of 80 mg / g is 5 parts by weight in solid content, polyvinyl alcohol PVA117 (manufactured by Kuraray Co., Ltd.) is 1 part by weight in solid content, and 94 parts of water. A coating solution was prepared. This coating solution is applied to a 75 μm thick polyethylene terephthalate film (Diawheel Co., Ltd.) as a base material using a bar coater so that the film thickness after drying becomes 10 μm, and dried to produce a film for plate making. did.
[0029]
The obtained plate-making film was transparent to ultraviolet rays and had good ink absorbability.
[0030]
An image was drawn on the obtained plate-making film using a plotter HP design jet 330 manufactured by Hewlett-Packard. However, the ink used is a water-soluble azo dye selected from mono- or disazo dyes, and contains a yellow dye having an absorption peak in light having a wavelength of 350 to 420 nm , which is disclosed in Japanese Patent Application No. 9-326656. A water-based ink with excellent light-shielding properties.
[0031]
A transparent plastic film on which an image is formed as an exposure mask is brought into close contact with the registered trademark “APR Flex” (manufactured by Asahi Kasei Kogyo Co., Ltd.), which is an FB type of photosensitive resin for polyurethane relief printing, and is exposed to a metal halide lamp (6 kw) for 5 minutes. The transparent plastic film was peeled off after exposure. Subsequently, it was washed with water for 3 minutes and exposed again in water for 10 minutes. Further, the surface of the photosensitive resin was rinsed for 5 minutes in accordance with a known method and then dried for 5 minutes to obtain a resin relief plate having a plate thickness of 0.7 mm and a Shore hardness of about 60 degrees. Using this relief printing, it was possible to carry out flexographic printing having a line width of 100 to 150 μm and good for package printing and cardboard printing. In addition, it was a favorable image when visual evaluation was performed about the obtained printed image.
[0032]
Comparative Example 1
Drawing was performed in the same manner as in Example 1 using the above-described plotter using a conventional inkjet OHP film, and plate making was performed in the same manner as in Example 1 using this as a photomask. The obtained plate-making film was not a clear printing plate and could not be used as a photomask film for printing plate-making.
[0033]
【The invention's effect】
According to the present invention, an inexpensive plate-making film having sufficient accuracy and dimensional stability and excellent mass productivity can be obtained.

Claims (2)

It has a transparent substrate and an ink-receiving layer containing 10 to 100 wt% of a binder based on the alumina hydrate and the alumina hydrate as an active ingredient, which is provided on the substrate, the ink-receiving a photomask film for printing plate making with image drawn by an inkjet method on the layer, the alumina hydrate have a suction capacity 20 to 100 mg / g, the image is in the light of the wavelength 350~420nm A photomask film for printing plate making, comprising an image of an aqueous ink containing a water-soluble azo dye selected from yellow mono- or disazo dyes having an absorption peak . The photomask film for printing plate making according to claim 1, wherein the alumina hydrate is pseudo boehmite.