JPH02244163A - Planographic printing plate and production thereof - Google Patents

Abstract

PURPOSE:To allow direct plate making from electric signals and to eliminate the need for a developing stage by incorporating powder which imparts an electrical conductivity into a conductive resin layer and incorporating UV curable silicone rubber into an ink repulsion layer. CONSTITUTION:The powder which imparts the electrical conductivity is incorporated into the conductive resin layer laminated on a base and the UV curable silicone rubber is incorporated into the ink repulsion layer. While metal powder and carbon black are usable as the powder to impart the electrical conductivity, the carbon black which is easily available and allows easy dispersion is more preferable. Polyorganosiloxane having an unsatd. hydrocarbon, such as vinyl group and the polyorganosiloxane in which the methyl group is combined with a silicon atom and which is added with a photoradical generating agent, such as bonzophenone, are used as the UV curable silicone rubber. The direct plate making is executed in this way; in addition, there is no developing stage and the good planographic printing plate is obtd. easily in a short period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a lithographic printing plate used in offset printing.

<Prior art> Plates for lithographic printing include: ■ A so-called 28 plate, which is a grained aluminum sheet coated with a photosensitive resin, is imagewise exposed and developed.

■After performing image forming processes such as corona charging, image exposure, and toner development on a plate material with a photosensitive layer made of zinc oxide powder and binder resin on the base, the non-image area is subjected to affinity treatment. The so-called electrofax method for producing lithographic printing plates.

■A printing plate material prepared by coating an alkali-soluble organic photoconductive compound layer on a conductive substrate, as described in Japanese Patent Publication No. 37-17162, etc., is used in a series of corona charging, image exposure, and toner development rings. After performing an electrophotographic image forming process, a lithographic printing plate may be prepared by etching away the photoconductive compound layer other than the image area using an alkaline water-soluble etching liquid using the toner layer as a resist.

The PS plate produced by the method (2) is used as a normal lithographic printing plate suitable for most printing, and can be produced by a simple process of exposure and development, but due to its sensitivity and sensitive wavelength range, it is not suitable for mercury lamps. This method requires close contact or projection exposure using ultraviolet rays such as UV rays, making scanning exposure using digital signals impossible, and in addition, the plate material is relatively expensive.

The lithographic printing plate produced by the electrofax method according to method (2) is suitable for office use and light printing of small quantities and can be easily manufactured, and the plate material is relatively inexpensive, so it has been widely used in recent years. In addition to being able to use only a light source with a limited wavelength range, such as a halogen lamp, the exposure conditions are narrow in that the original is mainly exposed to reflected light.

Method (2) can improve the photosensitivity and sensitive wavelength range (2), so it is possible to perform not only exposure using reflected light from the document, but also scanning exposure using Ar laser, He-Ne laser, and recently semiconductor laser, and it has become possible to perform scanning exposure using Ar laser, He-Ne laser, and in recent years, semiconductor laser. Progress is being made in so-called direct plate making, in which laser light is modulated and exposed using image data, but the printing plate manufacturing process is complicated, meaning that an etching process is required after charging, exposure, and development, and the processing time is long. However, not only is the apparatus large-scale and two types of processing liquids are required, but also the image is deteriorated because the toner image is used as a resist for etching, and it is difficult to reproduce fine patterns. There was also the problem that the plate material was expensive.

Also, JP-A-59-116759, JP-A-59-116759,
The lithographic printing plate, which has a photosensitive layer made of zinc oxide, phthalocyanine pigment, and binder resin, is an improved version of the electrofax method described in Publication No. 116760. Direct plate making using laser scanning exposure is possible.

However, all of the above-mentioned printing plates are offset printing plates that use water, and they have various problems caused by water, such as the balance between ink and water, emulsification of ink, and the influence of temperature. Printing was expected.

However, currently only PS plates made of a combination of photosensitive resin and silicone resin are in use, and there are currently no waterless printing plates that can be printed directly from digital data.

In addition, as disclosed in Japanese Patent Application No. 63-237167, graft polymerization was carried out between a conductive resin layer and an ink repellent layer containing reactive silicone oil laminated thereon to modify the surface of the plate material to be ink repellent. Since lithographic printing plates use a discharge rupture recording method, they can be made directly from digital data, and waterless lithographic printing is also possible.

However, this printing plate had the drawback of requiring a dissolution process with a solvent to remove the unpolymerized portion or the homopolymer of silicone oil after graft polymerization, which took time and effort. .

In addition, lithographic printing plates that use room-temperature-curing silicone rubber for the ink anti-finger layer do not require dissolution treatment using a solvent, but the slow curing speed makes it impossible to use a roll-up coating machine.
It had the disadvantage of poor productivity.

<Problems to be Solved by the Invention> The purpose of the present invention is to provide high quality and high rigidity printing that enables direct plate making from electrical signals, eliminates the need for a developing process, and enables printing without the need for dampening water. It is an object of the present invention to provide a lithographic printing plate having a high productivity with a short processing time and a method for manufacturing the same.

<! Means for Solving Iff> The present invention achieves the above object, in a lithographic printing plate formed by sequentially laminating at least a conductive resin layer and an ink repellent layer on a support substrate, the conductive resin layer has a conductive layer. A lithographic printing plate is characterized in that it contains a powder that imparts a UV curable silicone rubber in the ink-repellent layer, and in producing the lithographic printing plate, it is necessary to apply a powder in a resin on a supporting substrate. A step of providing a conductive resin layer made by dispersing powder that imparts conductivity, a step of laminating an ink repellent layer containing UV-curable silicone rubber thereon, a step of irradiating UV, and a step of applying a voltage to the image area. This is a method for producing a lithographic printing plate, characterized by comprising the steps of: removing the ink-repellent layer on the image by applying a voltage to cause discharge breakdown, exposing the conductive resin layer, and forming an ink-receptive image.

Function> Both the conductive resin layer and the ink repellent layer of this printing plate can be easily formed using a general coating method. In particular, the ink repellent layer made of UV-curable silicone rubber can be formed by short-term UV light. Sufficient hardness can be obtained even with irradiation, and it has excellent workability. Further, by making the film thinner, discharge breakdown easily occurs.

Furthermore, since the crosslinking points of the silicone rubber are strong 5i-C bonds, it exhibits excellent durability and high rigidity resistance.

In addition, since the plate-making method uses an electrical discharge destruction recording method, the plate can be made directly from digital data, and does not involve wet processes such as development.Furthermore, since the surface tension of the silicone rubber layer is extremely low, the conductive resin layer can be destroyed by electrical discharge. The exposed portion attracts ink, and the remaining silicone rubber layer that has not been destroyed by discharge has the property of repelling ink, making it possible to perform offset printing without using dampening water, that is, waterless planographic printing.

The present invention will be explained in detail below.

The lithographic printing plate of the present invention is generally one in which a conductive resin layer and an ink repellent layer are sequentially laminated on a supporting substrate.

The supporting substrate can be paper, plastic, a polymeric film such as polyvinyl chloride, or metal such as brass, copper, stainless steel, aluminum, or treated steel, and glass.

As the conductive resin layer, a resin layer in which powder imparting conductivity, such as carbon, is dispersed can be applied.

Metal powder and carbon black can be used as the powder that imparts conductivity, but carbon black is preferred because it is readily available and easily dispersed. Examples of carbon black include Furne black, Ketchen black, and acetylene black. can.

The resin is preferably one that can adhere to the room-temperature curable silicone rubber of the upper layer and exhibits ink receptivity after discharge breakdown, and specifically includes polyester resin, acrylic resin, epoxy resin, polyamide resin, phenol resin, melamine resin, Examples include acetal resin, urethane resin, silicone resin, and the like.

Carbon black content is 5-25% by weight based on resin
A ball mill, a paint shaker, an ultrasonic homogenizer sand mill, etc. can be used as the zero dispersion method. The thickness of the conductive resin layer can be set arbitrarily, but 5
μm or more, preferably 10 to 100 μm,
This conductive resin layer can be formed using an applicator, spray coater, bar coater, tip coater, doctor blade, or the like.

In addition, this chargeable resin layer can be used by itself without imparting conductivity as long as the resin itself has conductivity.

Regarding the UV-curable silicone rubber of the ink-repellent layer, for example, use the formula described below! A polyorganosiloxane having an unsaturated hydrocarbon such as a vinyl group represented by the formula (2) and a polyorganosiloxane having a methyl group bonded to a silicon atom represented by the following formula (2) are added with a photoradical generator such as bonsiphenone. Can be used.

Formula I R CHx ”” C+Si O+a R: Ca
H*a-1n=L2+32■ CI.

+O-S　i　-0+-J.

C11゜This silicone rubber may be used alone, but it may be used in combination with other U.
There is no problem in using a V-curable silicone rubber in combination. Of course, if there is a UV-curable silicone rubber other than those listed here that has excellent adhesive properties, it is also possible to use it.

The ink-repellent layer is formed by coating the silicone rubber diluted in a solvent if necessary. ! ! ! For cloth, applicator spray coater, bar coater, tip coater
A doctor blade etc. can be used.

Thereafter, the coated surface is cured by UV irradiation. As a UV light source, hydrogen discharge tube, xenon discharge tube,
High-pressure mercury lamps, ultra-high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, etc. can be used.

In this case, the amount of UV irradiation is preferably lomJ/c- or more in view of the reaction efficiency of the silicone rubber.

Regarding the layer structure of these plate materials, there is no particular restriction on the thickness of the supporting base, and the conductive resin layer has a thickness of 5 μm or more, preferably 10 g.
m or more is suitable. If the ink anti-TA layer is too thin, the ink repellency will be poor, and if it is too thick, it will be difficult to cure, and even if it is cured, discharge breakdown will not occur.
Suitably, the thickness is 0.5 μm or more and 10 μm or less, particularly from the viewpoint of image quality such as resolution.

The surface of the plate material thus obtained has a silicon layer having a lower surface tension than that of the lithographic printing ink, and has excellent ink repellency.

In order to form an image on the plate material, the silicon layer in the image area is destroyed by discharge destruction and the conductive resin layer is exposed.
It is sufficient to form an ink-receptive image area, that is, to write the image area on the printing plate by applying a voltage to a pin electrode or the like according to image information by scanning. The applied voltage is about 60 to 80V, and the recording speed is 110C.
Air pressure may be applied to the surface of the plate material in order to remove silicon pieces generated by discharge breakdown during image formation, which is preferably 1/sec or less.

Printing using the printing plate thus obtained can be performed using a normal offset printing machine, and waterless printing can be performed without supplying dampening water.

In addition, ordinary offset printing machines require many rollers and controls because the balance of ink and water subtly changes the printing condition, but waterless offset printing using the plate of the present invention can be used in principle. The number of rollers and control points should also be reduced.

In the present invention, during digital plate making using pin electrodes, image data taken from a scanner or the like and separated into each color plate of yellow plate, magenta plate, cyan plate, and black plate can be used as a modulation signal to the electrode voltage. It is possible to manufacture lithographic printing plates of each color used in color printing into a package. By printing these lithographic printing plates of each color in register, color printed matter can be obtained.

<Example> Hereinafter, the present invention will be explained in more detail with reference to Examples.

(Example 1) Epoxy resin (Epicoat 807) was used as the conductive resin layer.
(manufactured by Shell Chemical Co., Ltd.) 195g, dimethyldodecyalamine IQg as a catalyst, carbon black (CON
DUCTEX, SC, :] CI 7 Via Force (manufactured by Bonn) 30g was placed in a glass bottle with 150g of glass piece and dispersed for 30 minutes in a paint shaker (manufactured by Left Devil), and the thickness of the support base was 0.24- A coating film of 10 gm was formed using an aluminum plate Heparcoater, and 1
It was dried at 20°C for 2 hours.

Furthermore, UV-curable silicone rubber (XE
1? -610 manufactured by Toshiba Silicone Co., Ltd.) was applied using a bar coater to a film thickness of 12 μm.

After coating, use a 3kM ultra-high pressure mercury lamp in an N8 atmosphere for approximately 1m.
Exposure was carried out for 13 minutes from a height of I got it.

This is printed on a commercially available offset printing machine (An
-80) using Toyo Ink Co., Ltd.'s Aquares V as the ink and printing without dampening water. As a result, the background stain area rate at the beginning of printing was 0.1% or less (Viewback III manufactured by Toyo Ink Co., Ltd.), and the printed image density after printing 5000 sheets was 1.
．． Very high quality printed matter of 2 or more (Macbeth reflection densitometer RD-914) was obtained.

(Example 2) A lithographic printing plate was prepared in the same manner as in Example 1, except that acrylic resin (Dyanal LR-637 manufactured by Mitsubishi Rayon Co., Ltd.) was used as the resin for the conductive resin layer, and printing was carried out in the same manner. I went and the printed image density after printing 5000 sheets was 1.1.
This is the above, and a high quality printed matter similar to that of Example 1 was obtained.

(Example 3) A lithographic printing plate was prepared in the same manner as in Example 1, except that polyester resin (Vylon-200 manufactured by Toyobo Co., Ltd.) was used as the resin for the conductive resin layer, and printing was performed in the same manner. The printed image density after printing 5000 sheets was 1.2 or more, and a high quality printed matter similar to that of Example 1 was obtained.

(Comparative Example 1) Ink repellent layer 12 of Example 1. A lithographic printing plate was prepared in the same manner except that um was set to 0.3 μm. When similarly printed, the background stain area ratio of the non-image area was 35% or more.
Only low-quality prints with severe background stains were obtained.

(Comparative Example 2) When a lithographic printing plate was prepared in the same manner as in Example 1 except that the ink thickness was changed from 111112 μm to 35ym, the ink loss layer did not harden. When the curing time was changed from 13 minutes to 60 minutes, curing became possible, but when the plate was made in the same manner as in Example 1, no discharge breakdown occurred and no image was formed.

<Effects of the Invention> As explained above, according to the lithographic printing plate and the method for manufacturing a lithographic printing plate of the present invention, direct plate making is possible,
Moreover, there is no developing step, and a good lithographic printing plate can be obtained more easily and in a shorter time than with conventional methods.

Moreover, the mark is ¥1! The plate surface has high ink resistant properties, making it possible to create a waterless plate that does not require etching treatment before printing or dampening water during printing, and produces printed matter of high quality and high rigidity with little scumming.

Patent applicant Toppan Printing Co., Ltd. Representative: Kazuo Suzuki

Claims (2)

[Claims] (1) In a lithographic printing plate formed by sequentially laminating at least a conductive resin layer and an ink repellent layer on a support substrate, the conductive resin layer contains a powder that imparts conductivity, and the ink repellent layer contains UV rays. A lithographic printing plate characterized by containing curable silicone rubber. (2) A step of providing a conductive resin layer on the supporting substrate by dispersing powder that imparts conductivity in the resin, and applying U on the conductive resin layer.
A step of laminating an ink repellent layer containing V-curable silicone rubber, a step of irradiating UV, applying a voltage to the image area and removing the ink repellent layer in an image form by discharge destruction,
1. A method for producing a lithographic printing plate, comprising the steps of exposing a conductive resin layer and forming an ink-receptive image area.