JP2780281B2 - Lithographic printing plate and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lithographic printing plate used for offset printing.

<Prior art> Plates for lithographic printing are those in which a photosensitive resin is coated on a grained aluminum sheet.

A plate material provided with a photosensitive layer made of zinc oxide powder and a binder resin on a base is subjected to image forming processing such as corona charging, image exposure, and toner development, and then is subjected to lithographic processing by affinity treatment of a non-image portion. The so-called electrofax method for producing printing plates.

JP-B-37-17162 discloses a printing plate material in which an alkali-soluble organic photoconductive compound layer is coated on a conductive substrate, and is subjected to a series of electronic processes such as corona charging, image exposure, and toner development. After performing a photographic image forming process, a method of preparing a lithographic printing plate by etching away a photoconductive compound layer other than an image portion with an alkaline water-soluble etching solution using a toner layer as a resist may be mentioned.

PS plates are used as ordinary lithographic printing plates suitable for most printings, and printing plates can be manufactured by simple processes of exposure and development. However, there is a problem that scanning exposure using a digital signal is impossible, and the plate material is relatively expensive.

The lithographic printing plate by the electrofax method according to the method described above is widely used in recent years because the printing plate can be manufactured easily and easily for office use or small number printing, and the plate material is relatively inexpensive. Not only can a light source of a limited wavelength range such as a lamp be used, but also the exposure conditions are narrow, mainly reflecting light exposure of the original.

The method can improve the light sensitivity and the photosensitive wavelength range, so that not only exposure by the reflected light of the original document but also scanning exposure by an Ar laser, He-Ne laser, and recently a semiconductor laser is possible, and image data such as word processing The use of so-called direct plate making, which modulates and exposes a laser beam, is increasing, but the printing plate manufacturing process is complicated, that is, it requires an additional etching step after charging, exposure, and development. Is large and the processing solution is 2
In addition to the necessity of the type, the etching is performed using the toner image as a resist, so that an image is deteriorated, and it is difficult to reproduce a fine pattern. Also,
There was also a problem that the plate material was expensive.

Further, a lithographic printing plate having a photosensitive layer composed of a zinc oxide, a phthalocyanine pigment, and a binder resin obtained by improving the electrofax method described in JP-A-59-116759, JP-A-59-116760, etc. It can be developed and printed by the same processing as a zinc oxide plate, and enables direct plate making by scanning exposure with a semiconductor laser.

However, the above-mentioned printing plates are all offset printing plate plates using water, and 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, at present, only a PS plate combining a photosensitive resin and a silicone resin is in practical use, and there is currently no waterless printing plate capable of directly printing from digital data.

<Problems to be Solved by the Invention> An object of the present invention is to provide high quality and high printing durability, which enables direct plate making from an electric signal, does not require a development step, and enables printing without dampening solution. And a method of manufacturing the same.

<Means for Solving the Problems> The present invention for achieving the above object is a planographic printing plate comprising a support substrate, on which at least a conductive resin layer and an ink repellent layer are sequentially laminated, wherein the conductive resin layer A lithographic printing plate containing a powder for imparting conductivity, and containing a reactive silicone oil in an ink repellent layer. A conductive resin layer obtained by dispersing a powder for imparting conductivity to a conductive resin layer is provided, an ink repellent layer containing a reactive silicone oil is laminated thereon, and then graft polymerization is performed between the two layers to form a plate. After improving the material surface to ink repellency, apply voltage to the image area and discharge breakdown,
A method for producing a lithographic printing plate, comprising removing an ink repellent layer in an image form, exposing a conductive resin layer, and forming an ink receptive image area.

<Operation> The reactive silicone oil layer graft-polymerized on the conductive resin layer is a monomolecular layer or a thin layer close to the monomolecular layer, so that discharge breakdown easily occurs. Further, since the silicone oil layer is thin, an image portion and a non-image portion after discharge breakdown are well cut, and a high resolution can be obtained. In addition, since they are not merely laminated but are chemically reacted, they do not easily peel off and have high printing durability.

Further, since the discharge breakdown recording method is used for the plate making method, plate making can be made directly from digital data, and does not include a wet process such as development. Moreover, since the surface tension of the silicon oil layer is extremely small, the exposed portion of the conductive resin layer which is destroyed by discharge draws ink, and the layer of silicon oil remaining without discharge breakdown has a property of repelling the ink, Offset printing without fountain solution,
Waterless lithographic printing becomes possible.

 Hereinafter, the present invention will be described in detail.

The lithographic printing plate of the present invention is generally obtained by sequentially laminating a conductive resin layer and an ink repellent layer on a supporting substrate.

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

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

Metal powder and carbon black can be used as the powder for imparting conductivity, but carbon black which is easily available and easily dispersed is preferable. Examples of carbon black include farne black, ketchen black, and acetylene black.

As the resin, a polyester resin, an acrylic resin, an epoxy resin, a polyamide resin, an acetal resin, and a urethane resin can be used, but an epoxy resin having a high grafting efficiency and a high ink repellency after grafting is preferable. As an epoxy resin, Epicoat 807,819,1001
(Manufactured by Shell Chemical Co., Ltd.) and Araldite GY-260 (manufactured by ciba). The epoxy resin is heated and cured together with a catalyst such as an amine, but the higher the curing rate, the more the grafting tends to occur.

The content of carbon black is 5 to 25% by weight based on the resin
It is desirable that As a dispersion method, a ball mill, a paint shaker, an ultrasonic homogenizer, a sand mill or the like can be applied. The thickness of the conductive resin layer can be arbitrarily set, but is preferably 5 μm or more, and more preferably 10 to 100 μm.
This conductive resin layer can be formed by an applicator, a spray coater, a bar coater, a dip coater, a doctor blade or the like.

Drying after coating is preferably performed by heating with hot air of 100 ° C. or more for 2 minutes or more.

As the ink repellent layer, a reactive silicone oil that can react with the conductive resin layer can be used. That is, it is necessary that graft polymerization to the conductive resin surface be possible. An example is a reactive silicone oil having a (meth) acryloxyalkyl group. In particular, a reactive silicone oil represented by the following formula I has high reactivity and is suitable.

Although this reactive silicone oil may be used alone, other reactive silicones may be used in combination.
Of course, if there is a reactive silicone oil other than those mentioned above having excellent reactivity, it may be used.

In the grafting method, the reactive silicone oil is diluted and applied to a solvent as necessary. In the case of grafting by light, it is necessary to add a photo radical generator such as benzophenone. Thereafter, grafting is performed by irradiation with light (UV or visible light) or an electron beam.

Since the ink repellent layer may be a monomolecular layer or a thin layer close to the monomolecular layer, it is preferable to remove the unpolymerized portion or the homopolymer of silicone oil.

As the solvent, it is preferable to dissolve the silicone oil homopolymer without dissolving the conductive resin layer. Isobutylene, n-pentane, n-hexane, n-heptane, n-
Octane, methylcyclohexane and the like can be exemplified.

With respect to the layer constitution of these plate materials, the thickness of the supporting base is not particularly limited, and the conductive resin layer has a thickness of 5 μm or more, preferably 10 μm or more.
m or more, and the ink repellent layer is a monolayer or less, 10 μm
The following is suitable, and particularly preferably 5 μm or less from the viewpoint of image quality such as resolution.

The surface of the plate material thus obtained is formed with a silicon layer having a smaller surface tension than that of the lithographic printing ink, and is modified to have ink repellency.

In order to form an image on the plate material, discharge breakdown causes
The ink-receiving image portion may be formed by destroying the silicon layer in the image portion and exposing the conductive resin layer. That is, a voltage is applied to a pin electrode or the like in accordance with image information by scanning, and an image portion is written on a plate material. The applied voltage is preferably about 60 to 80 V, and the recording speed is preferably 10 cm / sec or less. Wind pressure may be applied to the surface of the plate material in order to remove silicon fragments generated by discharge breakdown during image formation.

Printing using the printing plate thus obtained can be performed by a normal offset printing machine, and waterless printing can be performed unless a dampening solution is supplied.

In addition, ordinary offset printing presses require a large number of rollers and controls because the balance between ink and water changes delicately.However, according to waterless offset printing using the plate of the present invention, in principle, The number of rollers and the places to control should also be reduced.

In the present invention, at the time of digital plate making with a pin electrode,
Yellow and magenta versions taken from scanners, etc.
Image data decomposed for each color plate of cyan plate and black plate,
When used as a modulation signal for the electrode voltage, a lithographic printing plate of each color used for color printing can be easily manufactured. Color printing is obtained by printing the lithographic printing plates of each color in register.

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

Example 1 An epoxy resin (Epicoat 80) was used as the conductive resin layer.
7, Ciel Chemical Co., Ltd.) 195 g, dimethyldodecylamine 10
g, 30 g of carbon black (CONDUCTEX, manufactured by SC Columbia Carbon Co., Ltd.) together with 150 g of glass beads in a glass bottle, dispersed with a paint shaker (manufactured by Red Devil) for 30 minutes, and a base paper having a basis weight of 120 g / m ² as a supporting substrate. A 10 μm coating film was formed using a bar coater and dried at 120 ° C. for 2 hours.

Further, on this surface, 150 g of a reactive silicone oil represented by the following formula II, 7 g of benzophenone, and 10 g of 2-butanone
0 g of a grafting agent was applied using a bar coater to a thickness of 5 μm.

After the application, a glass plate having a thickness of 3 mm is placed on the surface, and exposure is performed for 20 minutes from a height of about 1 m using a high-pressure mercury lamp of 100 W, and then n
-After immersing in hexane for 60 seconds at room temperature and rubbing the surface with absorbent cotton, dry at 30 ° C for 60 seconds by electrodrying, and record 8 cm / sec on the plate using a pin electrode with an applied voltage of 80 V. An image was formed at an image density of 32 lines / mm at a speed to obtain a lithographic printing plate.

This is a commercial offset printing machine (Ryobi printing machine AD
-80), printing was performed without dampening solution using AQUALES V manufactured by Toyo Ink. As a result, the area ratio of the printed background stain is 0.1
% (Viewback III manufactured by Toyo Ink Co., Ltd.)
A very high quality printed matter having a print image density of 1.2 or more after printing 0 sheets (Macbeth reflection densitometer RD-914) was obtained.

(Comparative Example 1) A lithographic printing plate was prepared in the same procedure as in Example 1 except that KF96 manufactured by Shin-Etsu Chemical Co., Ltd. was used as a silicone oil. That is, no ink repellent layer was formed in the silicone oil having no reactive group.

<Effects> As described above, according to the planographic printing plate of the present invention and the method for producing the same, direct plate making is possible, and furthermore, there is no development step, and a good planographic printing plate can be obtained more easily and in a shorter time than the conventional method. Obtained. In addition, the printing plate surface has high ink repellency, and can perform etching treatment before printing and waterless printing without the need for dampening water during printing.Furthermore, printed matter with less background smear and high quality and high printing durability is obtained. Obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-164050 (JP, A) JP-A-58-112796 (JP, A) JP-A-56-88139 (JP, A) JP-A-61-88 118295 (JP, A) Japanese Utility Model Showa 62-142051 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41N 1/00

Claims (2)

(57) [Claims] (1) at least a conductive resin layer on a supporting substrate;
A lithographic printing plate in which an ink repellent layer is sequentially laminated, wherein the conductive resin layer contains a powder for imparting conductivity, and the ink repellent layer contains a reactive silicone oil. Print version. 2. A method according to claim 1, further comprising: providing a conductive resin layer formed by dispersing a powder for imparting conductivity in a resin on a support base; and laminating an ink repellent layer containing a reactive silicone oil thereon. By performing graft polymerization between the two layers, after modifying the surface of the plate material to ink repellency, the voltage is applied to the image area to remove the ink repellent layer in an image-like manner by discharge breakdown,
A method for producing a lithographic printing plate, comprising exposing a conductive resin layer to form an ink-receiving image area.