JPH11143055A - Formation of planographic printing plate and original plate for planographic printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing method capable of creating a printing image plane having the high identifiability of image parts and non-image parts and excellent image quality without requiring an alkaline developer and further, a printing method allowing the iterative use of this original plate for printing. SOLUTION: Printing is executed by irradiating the original plate for printing having a thin layer of a metal oxide of a specific structure changing to hydrophilicity by irradiation with active light on its front surface to make the entire surface hydrophilic and subjecting this surface to plotting with a heat mode, thereby forming the printing surface of which the image regions accept ink. The ink remaining on the plate surface is washed away from the used printing plate, by which the iterative printing as the original plate for printing is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the field of general light printing,
More particularly, the present invention relates to lithographic printing, and particularly to a novel offset printing method and a printing plate capable of easily producing a printing plate.
More specifically, the present invention relates to a lithographic printing method which enables repeated use of a printing plate and a printing plate.

[0002]

2. Description of the Related Art Lithographic printing, especially offset printing, has been widely used because of the simplicity of the printing plate manufacturing process among many printing methods. ing. This printing technique is based on the immiscibility of oil and water, with the oily material or ink selectively retained in the image areas and the dampening solution in the non-image areas. Accordingly, when the printing surface is brought into direct contact with the surface to be printed or indirectly through an intermediate called a blanket, the ink in the image portion is transferred and printing is performed.

The main method of offset printing is a PS plate having an aluminum substrate as a support and a diazo photosensitive layer applied thereon. In the PS plate, the aluminum substrate is used as a support, the surface is grained, anodizing and other processes are performed to enhance the ink receiving capacity and the ink repulsion of the non-image area, improve the printing durability, and improve the printing surface. The image for printing is formed on the surface of the surface. Accordingly, offset printing has been provided with characteristics such as printing durability and high definition of the printing surface in addition to simplicity. However, with the spread of printed matter, further simplification of the offset printing method has been demanded, and many simple printing methods have been proposed.

Representative examples include the Copyrapid offset printing plate commercially available from Agfa-Gevaert, and US Pat.
No. 11656, Japanese Patent Application Laid-Open No. 7-56351, and the like. This is a printing method based on the preparation of a printing plate by a silver salt diffusion transfer method. Since the image is lipophilic, it can be used as a printing plate as it is, so it is practically used as a simple printing method. However, although simple, this method also requires a diffusion transfer development step using an alkaline developer. There is a demand for a simpler printing method that does not require a developing step with a developer.

The development of a method for manufacturing a simple printing plate in which the developing step using an alkali developing solution after image exposure is omitted has been developed from the above background. In the technical field of this simple printing plate, which is also called an unprocessed printing plate because the development step can be omitted, image formation by thermal destruction of an irradiated portion on an image recording surface mainly by imagewise exposure, image formation of an irradiated portion by imagewise exposure Image formation by lipophilicity (heat mode curing), and also lipophilicity of the irradiated part, but also by light mode curing, changes in surface properties due to photolysis of diazo compounds, heat mode fusion thermal transfer of image parts, etc. Means based on the principle have been proposed.

The technique disclosed as the simple offset printing method includes US Pat. No. 3,506,779.
No. 3,549,733 and No. 3,574,65
No. 7, No. 3,739,033, No. 3,832, 9
No. 48, No. 3,945,318, No. 3,962,
Nos. 513, 3,964,389 and 4,03
No. 4,183, No. 4,081,572, No. 4,6
Nos. 93,958, 731,317 and 5,23
No. 8,778, No. 5,353,705, No. 5,3
U.S. Patents Nos. 85,092 and 5,395,729 and European Patent 1068.

[0007] These are designed so as not to require a developing solution at the time of plate making. However, the difference between the lipophilic region and the hydrophilic region is insufficient, so that the image quality of the printed image is inferior and the resolution is poor. Inferior, difficult to obtain a printed screen with excellent sharpness, insufficient mechanical strength of the image surface, easily scratched, rather impaired simplicity by providing a protective film, etc., long-time printing This is accompanied by at least one of the drawbacks, such as insufficient durability to withstand, and shows that simply eliminating the alkali development step does not involve practicality. A strong demand for a printing plate preparation method that has various characteristics required for printing and that can easily produce a printing plate has not yet been satisfied.

As one of the above-mentioned non-processing type printing plate preparation methods, a printing plate preparation method utilizing the fact that zirconia ceramics become hydrophilic by light irradiation is disclosed in Japanese Patent Application Laid-Open No. 9-169098.
No. However, the light sensitivity of zirconia is insufficient, and the discriminability between the image part and the non-image part is insufficient due to an insufficient light conversion effect from hydrophobic to hydrophilic.

In addition to the above-described simple printing method that does not require a developing solution, if there is a means for easily reproducing and reusing a used printing original plate, it is advantageous from the two aspects of cost reduction and waste reduction. It is. To recycle the original printing plate,
The simplicity of the reproduction operation affects the practical value, but the simplification of the reproduction operation is a difficult task, and has been hardly studied in the past, and is slightly referred to as zirconia ceramic in JP-A-9-169098. It only discloses a special master material.

[0010]

A first object of the present invention is to provide an offset printing method which is simple and does not require an alkaline developer and has a sufficient image quality on a practical level. The first is to provide a printing method which does not require an alkali developing solution, has a second excellent resolving power, and has a high discriminability between an image portion and a non-image portion, and thus can produce a print screen of excellent image quality. That is. A second problem to be solved by the present invention is to provide a printing method capable of repeatedly using a printing original plate, in addition to the above-mentioned problem of a printing method having simplicity without deteriorating printing image quality. is there.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have changed the phenomenon that a specific metal oxide changes the hydrophilicity of the surface by light irradiation. Recognizing that hydrophilicity has the property of returning to its original state by heat treatment, diligently studying the possibility of applying this phenomenon to the simplification of printing methods and the reuse of printing plates to solve the above problems Again, the present invention has been completed. That is, the present invention is as follows.

1. RTiO_Three(R is an alkaline earth metal source
Child), AB_2-xC_xD_3-xE_xO_Ten(A is a hydrogen atom or
Alkali metal atom, B is alkaline earth metal atom or lead source
, C is a rare earth atom, D belongs to Group 5A element of the periodic table
E is a metal atom also belonging to the group 4A element,
x represents any numerical value from 0 to 2), SnO_Two, Bi_TwoO
_ThreeAnd Fe_TwoO_ThreeA thin layer consisting of at least one of
Printing original plate was irradiated with actinic light.
After that, draw in heat mode and create a printing plate
The method of making a lithographic printing plate characterized by the following.

2. 2. The method of preparing a lithographic printing plate as described in 1 above, wherein after the ink remaining on the used printing plate surface is washed away, printing is repeatedly performed using the printing original plate.

3. 3. The method for preparing a lithographic printing plate as described in 1 or 2 above, wherein the thin layer as described in 1 above is provided on a printing surface side of a plate cylinder of an offset printing press.

4. A lithographic printing plate precursor comprising the thin layer described in 1 above on the surface on the printing surface side, and used in the lithographic printing method described in 1 to 3 above.

[0016]

Embodiments of the present invention will be described below in detail. The present invention is based on the fact that a thin layer of a specific metal oxide has the property of changing its surface property to hydrophilic upon irradiation with actinic light, and the property of the surface changed by heat to the original property. Establishing technology to apply these phenomena to discrimination of ink receptivity and repellency and to apply them to the production of printing plates for offset printing and the recycling of used printing plates The feature point is that.

In the following description, the above-mentioned specific metal oxide used in the present invention is referred to as "photocatalytic metal oxide". Before discussing the details, it is necessary to mention the terminology used in this specification while adding light. Active light is light that is excited when a photocatalytic metal oxide is absorbed and changes its surface to hydrophilic. The details such as the light source and the wavelength will be described later. Further, “entire irradiation” refers to irradiation in which substantially uniform and local nonuniformity is practically not recognized over the entire printing surface. In contrast, "imagewise exposure"
This is exposure with light modulated so that the light receiving surface illuminance is distributed in an image-like manner. “Heat mode” is used in the sense that is commonly used in the industry, and other than the method of drawing by the action of heat by bringing a fine heating medium into contact with an image, the absorbed light is converted into heat energy. It refers to a method that uses the phenomenon that the result of conversion is a change caused by the action of heat instead of a photochemical change, and infrared, high-intensity short-time visible light and laser beam are used for drawing in heat mode. Can be In the following description, “thin film” and “thin layer” are synonymous.

The photocatalytic metal oxide used in the present invention will be described. R of RTiO ₃ is a metal atom belonging to an alkaline earth element of the periodic table such as magnesium, calcium, strontium, barium, beryllium, and strontium and barium are particularly preferred. R above
Is 2 as long as the sum is stoichiometrically consistent with the above equation.
More than one kind of alkaline earth metal atom can be shared.

In the compound represented by the general formula AB _2-x C _x D _{3-x Ex} O ₁₀ , A is a monovalent selected from a hydrogen atom and an alkali metal atom such as sodium, potassium, rubidium, cesium and lithium. Two or more of the atoms may coexist as long as their sum matches the above formula in stoichiometry.

B is an alkaline earth metal atom or a lead atom as defined above for R, and two or more atoms may coexist as long as they are stoichiometrically matched as described above. C is a rare earth atom, preferably scandium, yttrium, lanthanum, cerium, praseodymium, neodymium,
It is an atom belonging to lanthanoid elements such as holmium, europium, gadolinium, terbium, thulium, ytterbium, and lutetium,

D is 1 selected from the group 5A elements of the periodic table.
More than species include nitrogen, phosphorus, arsenic, antimony, bismuth. Further, as long as the stoichiometric relationship is satisfied, two or more group 5A elements may coexist. E is also silicon,
It is a metal atom belonging to a group 4A element such as germanium, tin, and lead, and two or more kinds of group 4A metal atoms may coexist. x represents an arbitrary numerical value of 0 to 2.

In the present invention, the above RTiO_Three, A
B_2-xC_xD_3-xE_xO_Ten, SnO _Two, Bi_TwoO_Threeas well as
Fe_TwoO_ThreeAt least one of them alone or two or more
The surface of the original printing plate as a photosensitive layer using a thin layer composed of combinations
To be provided.

This thin layer has a property that its surface becomes hydrophilic by irradiation with actinic light. Utilizing this characteristic, imagewise exposure is performed using active light to generate an imagewise hydrophilic portion on the exposed surface, and then the surface is brought into contact with the printing ink so that the image area receives the ink. Printing is performed by forming a printed surface, and after the printing is completed, the ink remaining on the printing plate surface used is washed away, and then the original plate is uniformly heated to 80 ° C. or higher, and the exposed portion that has been rendered hydrophilic is obtained. Is returned to the original hydrophobicity, and the entire surface becomes a uniform ink-receptive hydrophobic surface, so that the printing original plate is reproduced. Therefore, it is a feature of the offset printing method of the present invention that printing can be repeatedly performed using the printing master.

The phenomenon that the surface of the metal oxide is made hydrophilic by a photocatalytic reaction is described in JP-A-9-70541.
No. 9-77535, it is also possible to make the surface hydrophilic by active light and to make the surface hydrophobic by light irradiation in heat mode or heating by the heat energy itself. The idea of applying these phenomena to a new type of offset printing that repeatedly uses the original is a new technical idea.

In order to provide the above-mentioned photocatalytic metal oxide used in the present invention on the surface of an original plate, for example, a method of coating a dispersion of the above-mentioned oxide fine particles on an original plate of a printing plate, or after coating, firing. The method of reducing or removing the binder by, the method of forming a film of the above oxide on the original plate of the printing plate by various vacuum thin film methods, for example, after applying an organic compound such as a metal element alcoholate on the original plate, Any known method can be used, such as a method of hydrolyzing and further performing calcination oxidation to form a metal thin film having an appropriate thickness, and a method of heating and spraying an aqueous solution of a hydrochloride or a nitrate containing the above-mentioned metal.

The above or the method of applying the barium titanate fine particles includes a method of applying a mixed dispersion of barium titanate and silicon to form a surface layer, and a method of applying barium titanate and an organopolysiloxane or a monomer thereof. And the like. Further, it can be applied by dispersing in a polymer binder which can coexist with the oxide in the oxide layer. Oxide fine particle binder
For this, a polymer having dispersibility in barium titanate fine particles can be widely used. Examples of preferred binder polymers include polyalkylene polymers such as polyethylene, polybutadiene, polyacrylate, polymethacrylate, polyvinyl acetate, polyvinyl formate, polyethylene terephthalate, polyethylene naphthalate, polyvinyl alcohol, partially saponified polyvinyl alcohol, Hydrophobic binders such as polystyrene are preferred, and these resins may be mixed and used. In this method, in addition to barium titanate, magnesium titanate, calcium titanate, strontium titanate, or an intermolecular compound or mixture thereof can be similarly formed into a thin film.

In the same manner, CsLa ₂
NbTi ₂ O ₁₀ fine particles can be applied. C
The sLa ₂ NbTi ₂ O ₁₀ fine particles are obtained by finely pulverizing Cs ₂ CO ₃ , La ₂ O ₃ , NbO ₅ , and TiO ₂ corresponding to the stoichiometry in a mortar, and placing the mixture in a platinum crucible at 130 ° C. for 5 hours. After baking, it was cooled and then put in a mortar and crushed into fine particles of several microns or less. The CsLa ₂ NbTi ₂ O ₁₀ fine particles were dispersed in a binder in the same manner as the above-mentioned barium titanate, and coated to form a thin film. This method uses Cs
Not limited to La ₂ NbTi ₂ O ₁₀ type fine particles, HCa _{1.5
La 0.5 Nb 2. 5 Ti 0.5 O} 10, LaNbTi 2 O 10 such as previously described _{AB 2-x C x D 3} -x E x O 10, (0 ≦ x ≦ 2)
Applied to

As a method for forming the photocatalytic metal oxide layer using the above-described vacuum thin film forming method, a sputtering method or a vacuum thin film forming method is generally used. In the sputtering method, a single or binary oxide target is prepared in advance. For example, a barium titanate final thin film can be obtained by performing RF sputtering in an argon / oxygen mixed atmosphere while maintaining the temperature of the support for the deposited film at 450 ° C. or higher using a barium titanate target. For controlling the crystallinity, post-annealing may be performed at 300 to 900 ° C. as necessary. In this method, a thin film can be formed on the aforementioned RTiO ₃ (R is an alkaline earth metal atom) and other photocatalytic metal oxides by adjusting the substrate temperature optimal for controlling the crystal in the same manner. . For example, when a tin oxide thin film is provided, a substrate temperature of 120
A barium titanate crystal thin film was obtained by performing RF sputtering in an argon / oxygen mixed atmosphere at a temperature of 5 ° C.
At 0/50 and RF power of 200 W, a thin film suitable for this purpose can be obtained.

The above method using a metal alcoholate is also a method capable of forming a desired thin film without using a binder. To form a barium titanate thin film, a mixed alcohol solution of barium ethoxide and titanium butoxide is applied on a silicon substrate having SiO ₂ on its surface, and the surface is hydrolyzed, and then heated to 200 ° C. or more. It is possible to form a thin film of barium titanate. This scheme other RTiO ₃ described above (R is an alkaline earth metal _{atom), AB 2-x C x} D 3-x E x O 10 (A,
B, C, D, and E respectively represent the contents of the above definition),
It can be applied to the formation of thin films of SnO ₂ , Bi ₂ O ₃ and Fe ₂ O ₃ .

Metal oxidation exhibiting the above photocatalytic function
The method of forming a thin film is also based on a system without a binder.
It is possible to form a target thin film. SnO_TwoForm a thin film of
SnCl_FourHeat hydrochloric acid aqueous solution to over 200 ° C
Sprays on quartz or crystalline glass surfaces to form thin films
can do. This method uses SnO_TwoIn addition to thin film
RTiO mentioned_Three(R is an alkaline earth metal atom), AB
_2-xC_xD_3-xE_xO _Ten(A, B, C, D, E are each
Represents the content of the above definition), Bi_TwoO_ThreeAnd Fe_TwoO
_ThreeCan be applied to the formation of any of the thin films.

In any of the above cases, the thickness of the metal oxide thin film is preferably from 1 to 100,000 angstroms, and more preferably from 10 to 10,000 angstroms. More preferably, the thickness is set to 3000 angstroms or less to prevent distortion of light interference. Further, it is convenient that the thickness is 50 Å or more in order to sufficiently exhibit the photoactivation effect.

In the thin layer of the photocatalytic metal oxide when a binder is used, the volume ratio of the metal oxide is 50%.
It is preferable that the oxide occupy 90% or more, more preferably 90% or more, and more preferably a continuous layer of the oxide, that is, substantially 100%. In addition, it may be effective to dope a certain metal in order to enhance the property of changing the hydrophilicity of the surface by light irradiation. For this purpose, doping of a metal having a low ionization tendency is suitable. , Pd, Au, Ag, Cu, Ni, F
It is preferable to dope e and Co. Further, a plurality of these preferable metals may be doped.

Various forms and materials can be used for the printing plate according to the present invention. For example, a method of directly providing an oxide layer by the above-described method such as vapor deposition, immersion or application of a photocatalytic metal oxide on the surface of a plate cylinder of a printing press, and providing a photocatalytic metal oxide layer on a surface of a metal plate. Is wound around a plate cylinder to form a printing plate, and as the metal plate, an aluminum plate, stainless steel, nickel, or a copper plate is preferable, and a flexible (flexible) metal plate can be used. In addition, a flexible plastic support such as polyesters and cellulose esters can also be used. An oxide layer may be provided on a support such as waterproofed paper, polyethylene laminated paper, or impregnated paper, and it may be used as a printing plate.

In the present invention, when a photocatalytic metal oxide layer is provided on a support, the support used may be
Dimensionally stable plate-like material such as paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, stainless steel, etc.), plastic film (For example, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), or a metal as described above is laminated or deposited. Torn paper,
Alternatively, a plastic film or the like is included.

Preferred supports are polyester film, aluminum, or SUS which is not easily corroded on a printing plate.
An aluminum plate, which is a plate, among which a dimensional stability is good and which is relatively inexpensive, is particularly preferable. Suitable aluminum plates are a pure aluminum plate and an alloy plate containing aluminum as a main component and containing a trace amount of a different element, and may be a plastic film on which aluminum is laminated or vapor-deposited. The foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, titanium and the like. The content of the foreign element in the alloy is at most 10% by weight or less. Aluminum which is particularly preferred in the present invention is pure aluminum. However, completely pure aluminum is difficult to produce due to refining technology, and therefore may contain a slightly different element. As described above, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate of a conventionally known and used material can be appropriately used. The thickness of the support used in the present invention is about 0.0
About 5 mm to 0.6 mm, preferably 0.1 mm to 0.4 mm,
Particularly preferably, it is 0.15 mm to 0.3 mm.

Prior to roughening the aluminum plate, if necessary, a degreasing treatment with, for example, a surfactant, an organic solvent or an alkaline aqueous solution for removing the rolling oil on the surface is performed. The surface roughening treatment of the surface of the aluminum plate is performed by various methods, for example, a method of mechanically roughening the surface, a method of electrochemically dissolving the surface, and a method of selectively dissolving the surface chemically. It is performed by the method of causing. As a mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, and a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing an alternating or direct current in a hydrochloric acid or nitric acid electrolyte. Further, a method combining both of them can be used as disclosed in JP-A-54-63902. The aluminum plate thus roughened is subjected to an alkali etching treatment and a neutralization treatment, if necessary, and then subjected to an anodic oxidation treatment, if desired, in order to increase the water retention and abrasion resistance of the surface. As the electrolyte used for the anodic oxidation treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. Generally, sulfuric acid,
Hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of the electrolyte.

The conditions of the anodizing treatment vary depending on the electrolyte to be used and cannot be specified unconditionally. However, in general, the concentration of the electrolyte is 1 to 80% by weight, the solution temperature is 5 to 70 ° C., and the current density is 5 to 60 A. / dm ² , voltage 1-100V, electrolysis time 10
A range of seconds to 5 minutes is appropriate. The amount of anodized film printing resistance is inadequate or non less than 1.0 g / m ^2,
The non-image portion of the lithographic printing plate is easily scratched, and so-called "scratch stain" in which ink adheres to the scratched portion during printing is likely to occur.

A printing plate having a photocatalytic metal oxide surface layer is inherently lipophilic and accepts ink. However, when imagewise exposure is performed, a portion irradiated with light becomes hydrophilic,
Stop accepting ink. After that, when the imagewise exposure in the heat mode is performed, the light receiving portion changes to lipophilic and has a property of receiving ink. Therefore, the imagewise exposed printing plate is brought into contact with the offset printing ink so that the non-image area retains the dampening solution, the image area forms a printing surface that has received the ink, and the printing surface contacts the printing surface. Then, printing is performed by transferring the ink.

The "change between lipophilicity and hydrophilicity by light irradiation" 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, and conversely, when the water droplet repels (water repellency, that is, lipophilicity), the contact angle increases. In other words, the master having the photocatalytic metal oxide surface layer of the present invention originally has a high contact angle with water, but the contact angle sharply decreases upon irradiation with actinic light, and the lipophilicity decreases. The ink-repelling property changes to form an ink-holding portion and a water-holding portion on the plate surface in an image-like manner, and the ink is transferred to the printing surface by coming into contact with an image receiving sheet such as paper.

In the present invention, the entire surface is exposed to actinic light prior to the formation of the lipophilic image to make the printing plate surface uniformly hydrophilic. Activating light used for overall exposure
A so-called surface exposure method for simultaneously irradiating the entire surface, a full-surface exposure method by moving slit-like light, or a scanning exposure method for scanning the entire surface with a light beam may be used. In the latter case, if the beam scanning interval is small enough to not substantially affect printing, it can be regarded as uniform exposure. Generally, if the light source is a laser light source,
A beam scanning exposure method is advantageous, and an incoherent divergent light source such as a light bulb or a discharge tube is advantageous to a surface exposure method. The active light that excites a thin layer containing a photocatalytic metal oxide as a main component has a photosensitive range of 400 nm or less, such as mercury lamps, tungsten halogen lamps, other metal halide lamps, xenon lamps, and other discharge tubes that emit ultraviolet light. Can be used.
Further, as the excitation light, a helium cadmium laser having an oscillation wavelength of 325 nm or an oscillation wavelength of 351.1 to
A water cooled argon laser at 363.8 nm can also be used. Further, in a gallium nitride laser system in which near-ultraviolet laser oscillation has been confirmed, the oscillation wavelength is set to 360 to
An InGaN quantum well semiconductor laser having a wavelength of 440 nm,
And a waveguide MgO having an oscillation wavelength in the range of 360 to 430 nm
-LiNbO ₃ inversion domain wavelength conversion device type laser is also applicable.

The photocatalytic metal on the surface layer depends on the amount of irradiation.
Oxide changes to hydrophilic by light absorption excitation
All photocatalytic metal oxides constituting the surface layer are activated
And further light irradiation change the degree of hydrophilicity further
I will not do it. The preferable irradiation light intensity is a photocatalytic metal mold.
Depends on the nature of the imaging layer
Although it depends on the wavelength and spectral distribution of light, it is usually used for printing
The surface exposure intensity before modulation with an image is 0.05 to 100 jo
ule / cm^Two, Preferably 0.05 to 10 joule
/ Cm^Two, More preferably 0.05 to 5 joule / c.
m ^TwoIt is. In addition, the reciprocity law has been almost established for light irradiation.
For example, 10 mW / cm^TwoExposure for 100 seconds
Also 1W / cm^TwoExposure for 1 second with the same effect
The choice of light source is limited as long as it emits active light
There is no. The amount of irradiation is determined by laser scanning.
Or a surface exposure method using a divergent light source.
This is a level of light that does not cause any problem.

In order to form an oleophilic image portion on the printing plate surface whose entire surface is uniformly hydrophilized, the printing plate surface is heated imagewise. Examples of the means for imagewise heating include a thermal head, a light-to-heat conversion head (light-to-heat conversion head), and a method of irradiating a heat ray through an image mask. A typical example of image-like heating by a thermal head is a method in which a fine heating element is brought into contact with the image to heat it like an image. The method of imagewise exposure may be either a scanning method or a surface exposure method. The former is an image-like writing by a beam, and the latter is a flash exposure or a slit moving exposure of a high illuminance through a heat-opaque image mask. An infrared light source is particularly preferable as the former light source, and a scanning exposure method in which a light beam from an infrared laser light source is scanned may be used. Also in the latter case, an infrared light source is preferable, and image printing of a surface exposure system using an infrared light bulb is preferable. In addition, the electricity stored in the large-capacity capacitor can be discharged at a time, and drawing can be performed by high-intensity short-time flash exposure. Suitable exposure dose is 0.05-10
joule / cm ² , preferably 0.05 to 5 joule / c
m ² .

According to the present invention, in the recording in the heat mode,
When the drawing step is performed by contact electrothermal drawing with a heating element other than the imagewise exposure, a preferable drawing means is printing and printing by a thermal head used in a thermosensitive recording type printer.

The above-mentioned photosensitivity that causes a change from hydrophobic to hydrophilic by light is described in zirconia ceramics (JP-A-9-169098), which has been disclosed in both properties and mechanism.
Is different from the photosensitivity. For example, the sensitivity is described as a laser beam of 7 W / μm ² for zirconia ceramic, 70 joule / cm ^{2 when} the pulse duration of the laser beam is 100 nanoseconds, and the photocatalytic metal oxide layer Approximately one order of magnitude lower than sensitivity. Although the mechanism is not sufficiently elucidated, it is considered to be a photo-exfoliation reaction of the lipophilic organic deposit, and is different from the photo-change mechanism of zirconia.

After performing image printing heat mode exposure or heat mode contact heating drawing on the surface layer of the photocatalytic metal oxide which has been rendered hydrophilic by the entire surface irradiation, the printing original plate is sent to the offset printing process without development processing. be able to. Therefore, it has many advantages, mainly simplicity, as compared with the known lithographic printing method. That is, as described above, the chemical treatment with the alkaline developer is unnecessary, and the accompanying wiping and brushing operations are not required, and further, there is no environmental load due to the discharge of the waste developer.

The exposed area of the lithographic printing plate obtained as described above is sufficiently hydrophilic. However, if desired, washing water, a rinsing solution containing a surfactant, a gum arabic or a starch derivative may be used. It is post-treated with a desensitizing solution containing the same. As the post-processing when the image recording material of the present invention is used as a printing plate material, these processings can be used in various combinations. As a method, with a sponge or absorbent cotton impregnated with the surface conditioning liquid, apply on a lithographic printing plate,
A method in which a printing plate is immersed in a vat filled with a surface-conditioning solution and applied, or an automatic coater is used. Further, it is more preferable that the application amount is made uniform by using a squeegee or a squeegee roller after the application. The application amount of the surface conditioning liquid is generally 0.03 to
0.8 g / m ² (dry weight) is appropriate. The lithographic printing plate obtained by such a process is set on an offset printing machine or the like and used for printing a large number of sheets.

Next, a process of reproducing the printing plate after printing will be described. After the printing is completed, the printing plate is washed off the attached ink using a hydrophobic petroleum-based solvent. As the solvent, there are aromatic hydrocarbons such as kerosene and isoper as commercially available printing ink dissolving liquids, and in addition to these, benzol, toluene, xylol,
Acetone, methyl ethyl ketone and a mixed solvent thereof may be used.

The printing plate from which the ink has been washed away is stored in an arbitrary place unless exposed to a high temperature to prepare for the next printing.
The used printing plate can be used again for printing by repeating the heat-mode imagewise exposure again by making the surface hydrophilic by the entire surface exposure described above.

Although the number of reproducible printings of the printing plate according to the present invention is not completely understood, it is at least 15 times or more. It is considered that it is restricted by mechanical deformation (strain) of the plate material.

[0050]

The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. Example 1 0.01% by weight of copper to 99.5% by weight of aluminum,
A 0.30 mm-thick rolled plate of JIS A1050 aluminum material containing 0.03% by weight of titanium, 0.3% by weight of iron, and 0.1% by weight of silicon is coated with a 400-mesh pumistone (manufactured by Kyoritsu Ceramics) in a weight of 20%. % Aqueous suspension and a rotating nylon brush (6,10-nylon), the surface of which was grained, and then thoroughly washed with water. This was immersed in a 15% by weight aqueous sodium hydroxide solution (containing 4.5% by weight of aluminum), etched so that the amount of aluminum dissolved was 5 g / m ² , and washed with running water. Furthermore, 1
Neutralized with 0.7% by weight nitric acid and then in an aqueous solution of 0.7% by weight of nitric acid (containing 0.5% by weight of aluminum);
160 clones / dm ² using a rectangular wave alternating waveform voltage of 5 volts and a cathode voltage of 9.3 volts (current ratio r = 0.90, current waveform described in Examples of Japanese Patent Publication No. 58-5796). The electrolytic surface roughening treatment was performed with the amount of electricity at the time of anode.
After washing with water, it was immersed in a 10% by weight aqueous solution of sodium hydroxide at 35 ° C., etched so that the amount of aluminum dissolved was 1 g / m ² , and then washed with water. Next, it was immersed in a 30% by weight aqueous sulfuric acid solution at 50 ° C., desmutted, and washed with water.

Further, a porous anodic oxide film forming treatment was performed in a 20% by weight aqueous sulfuric acid solution (containing 0.8% by weight of aluminum) at 35 ° C. using a direct current. That is, electrolysis was performed at a current density of 13 A / dm ² , and the anodic oxide film weight was adjusted to 2.7 g / m ² by adjusting the electrolysis time. After washing this support with water,
It was immersed in a 3% by weight aqueous solution of sodium silicate at 70 ° C. for 30 seconds, washed with water and dried. The aluminum support obtained as described above had a reflection density of 0.30 and a center line average roughness of 0.58 μm as measured by a Macbeth RD920 reflection densitometer. Next, this aluminum support was set in a sputtering apparatus, and 5.0 × 10 ⁻⁷ To
Evacuate to rr. The support was heated to 500 ° C.
The gas pressure was adjusted to 5 × 10 ⁻³ Torr so that r / O ₂ became 60/40 (molar ratio). RF power of 200 W was applied to a 6-inch φ barium titanate sintered target to form a barium titanate thin film having a film pressure of 1000 °. X
According to the line analysis method, this thin film was polycrystalline. The sample was cut into a size of 510 x 400 mm to obtain a sample. The contact angle of the surface of the sample was measured by the air drop method using CONTACT-ANGLE METER CA-D manufactured by Kyowa Interface Science Co., Ltd. 5
5 degrees.

A light source device for use in baking USIO made by Ushio Electric Co., Ltd., UNIREC URM-60, is applied to the surface of the barium titanate thin film.
Light intensity 25 mW / cm ² using GH-60201X
Irradiation was performed for 2 minutes under the following conditions. When measured again with the contact angle measuring device described above, the contact angle with water (water droplets in the air) was between 5 and 7 degrees at any part of the plate surface. On this sample, a solid-state infrared laser beam having an output of 10 W was focused to a beam width of 45 μm to perform drawing by scanning exposure.

The printing plate obtained by laser beam drawing in this way was set on a single-sided printing machine of Oliver 52 manufactured by Sakurai, and the dampening water was purified water and the ink was manufactured by Dainippon Ink and Chemicals, Inc.
Offset printing was performed on 1,000 sheets using NewChampion F gloss 85 ink. From the start to the end, a clear printed matter with no stain on the non-image portion was obtained, and no damage to the printing plate was observed.

Example 2 Next, the surface of the printing plate used in Example 1 was soaked in a waste with a printing ink cleaning liquid Daiclean R (released by Dainippon Ink and Chemicals, Inc.) and washed carefully to remove the ink. did. Then, under the same conditions as in Example 1, USHIO
Light source device for IO printing, Unirec URM-600 type G
Using H-60201X, the entire surface was exposed under a light intensity of 25 mW / cm ² for 2 minutes. The contact angle of the surface returned between 5 and 7 degrees at any part of the sample surface. Then, the sample was subjected to laser image exposure using a solid-state infrared laser having an output of 10 W of Example 1 and having a different drawing image only under the same conditions.

This plate was set on a single-sided printing machine of Oliver 52 manufactured by Sakurai Co., Ltd., and the dampening solution was purified with pure water, and the ink was coated with a Newchampion F gloss 85 ink manufactured by Dainippon Ink and Chemicals, Inc.
00 sheet offset printing was performed. The infrared laser drawing portion received the ink, and the background was protected with a fountain solution to obtain a clear print from start to finish, with no damage to the printing plate. When the above repetition was performed five times, no change was observed in the sensitivity of the surface property change due to the light of the plate, the sensitivity of laser drawing, the reproducibility of the contact angle, etc. As described above, from the results of Examples 1 and 2, the printing original plate having the barium titanate heat-sensitive layer provided on the aluminum support enables printing by heat mode optical drawing, and the plate is reproduced and reproduced only by washing and removing the ink. It has been shown that it can be used.

Example 3 An original printing plate sample was prepared on an aluminum support in exactly the same manner as in Example 1. USIO made by Ushio Electric Co., Ltd.
Light source device for printing Unirec URM-600 type GH
Using -60201X, under light intensity 10 mW / cm ² 2
The whole surface was irradiated for 5 minutes. When measured again by the above-mentioned contact angle measuring device, the contact angle was between 5 and 7 degrees. Ta-S
1 with Sialon wear protection layer on iO ₂ heating resistor
Using a thermal printer in which thermal heads of 50 μm × 150 μm were arranged at intervals of 250 μm, the thermal print was performed by bringing the thermal head into contact with the barium titanate surface layer. The temperature of the used thermal head reached 450 ° C. by applying a current of 20 msec, and it was confirmed by separately performing temperature measurement. The recording speed was 400 msec / m.

The printing plate thus obtained was set on a single-sided printing press of Oliver 52 manufactured by Sakurai Co., Ltd.
Offset printing was performed on 500 sheets of ink using New Champion F gloss 85 black manufactured by Dainippon Ink and Chemicals, Inc.
From the start to the end, a clear print without stain was obtained in the non-image area, and no damage to the printing plate was observed.

Example 4 The surface of the plate after printing in Example 3 was coated on the surface with a printing ink cleaning liquid Daiclean R (a sales agency; Dainippon Ink and Chemicals, Inc.).
Was soaked in a waste cloth and washed carefully to remove the ink. Under the same conditions as in Example 3, the USIO baking light source device UNIREC URM-600 type GH-
25 with light intensity of 10 mW / cm ² using 60201X.
The whole surface was irradiated for minutes. The surface contact angles were between 5 and 7 degrees for any part of the sample surface. Next, a barium titanate surface layer which had been washed under the same conditions was printed on the surface of this sample in a character pattern different from that of Example 3 by raising the temperature of the barium titanate surface under the same conditions.

This plate was set on a single-sided printing machine of Oliver 52 manufactured by Sakurai Co., Ltd., and the dampening solution was purified with pure water and the ink was dried using Newchampion F gloss 85 ink manufactured by Dainippon Ink and Chemicals, Inc.
00 sheet offset printing was performed. Clear prints were obtained from the start to the end, and no damage to the printing plate was observed. When the above-mentioned repetition was performed five times, no change was observed in the photosensitivity for making the plate hydrophilic, the contact angle, the heat sensitivity in heat mode drawing, and the like. The results indicate that the barium titanate thin film layer can be printed easily by direct heating and drawing with a printer head, and can be reused repeatedly by washing and removing the printing original plate with ink.

Example 5 A stainless steel support having a thickness of 100 μm was set in a sputtering apparatus, and evacuated to 5 × 10 ⁻⁷ Torr. The support was heated to 120 ° C. and the gas pressure of the argon / oxygen mixed gas (50/50 molar ratio) was set to 5 × 10 ⁻³ Torr.
Adjusted to r. RF power of 150 W was applied to a 6-inch φSnO ₂ sintered target to form a thin film of tin oxide with a film pressure of 1000 Å. This original plate was cut into a size of 510 × 400 mm to obtain a sample.

CONTACT-ANGLE ME manufactured by Kyowa Interface Science Co., Ltd.
When the contact angle of the surface was measured by the air drop method using TER CA-D, 51 degrees was obtained. Ushio Electric Co., Ltd. USIO baking light source device UNIREC URM-600 type GH-60
Exposure was performed for 10 minutes under the light intensity of 25 mW / cm ² using 201X. When the contact angle was measured again using the above contact angle measuring device, the contact angle was reduced to 5 degrees.

The tin oxide thin film was irradiated with solid-state infrared laser light in the same manner as in Example 1 to perform drawing by heat mode exposure by photothermal conversion. This plate was set on a single-sided printing machine of Oliver 52 manufactured by Sakurai, and the dampening water was pure water, and the ink was New Champion F gloss 85 manufactured by Dainippon Ink and Chemicals, Inc.
Offset printing was performed on 1000 sheets using black ink. From the start to the end, a clear printed matter with no stain on the non-image portion was obtained, and no damage to the printing plate was observed.

Example 6 The surface of the printing plate used in Example 5 was soaked in a rag with a printing ink cleaning liquid Daiclean R (released by Dainippon Ink and Chemicals, Inc.) and carefully washed to remove the ink. . In this state, the same light source (printing light source device manufactured by Ushio Electric Co., Ltd.) was used, and the same light intensity (25 mw / cm ² ) was used.
For 10 minutes. When the contact angle of the surface was measured by a water drop method in the air, 5 ° was obtained. Further, different images were drawn with the same infrared laser beam as in Example 5.

This plate was set on a single-sided printing machine of Oliver 52 manufactured by Sakurai Co., Ltd.
000 sheets of offset printing were performed. Clear prints were obtained from the start to the end, and no damage to the printing plate was observed. When the above-mentioned repetition was performed five times, no change was observed in the photosensitivity to hydrophilicity of the plate, the contact angle, and the photosensitivity to heat mode drawing. From these results, it was shown that even when a printing plate having a tin oxide photosensitive layer provided on an aluminum support was used, simple printing by heat mode drawing was possible, and the printing plate could be repeatedly reproduced and used.

Example 7 An aluminum support anodized in the same manner as in Example 1 was treated with cesium ethoxide, titanium butoxide, lanthanum isobutoxide, niobium ethoxide corresponding to the stoichiometric ratio of CsLa ₂ NbTi ₂ O _10. 200 ° C after immersing in a 20% ethanol solution containing
By heating as described above, a thin film of CsLa ₂ NbTi ₂ O _{10 having} a thickness of 1000 Å was formed on the surface of the aluminum support.

This aluminum plate with a composite metal oxide thin film was cut into a size of 510 × 400 mm to obtain a sample. The entire surface of the surface was exposed for 5 minutes at a light intensity of 25 mW / cm ² using a USIO baking light source device UNIREC URM-600 Model GH-60201X manufactured by Ushio Inc. Kyowa Interface Science Co., Ltd. CONTACT-ANGLE METERCA-
Using D, the contact angle of the surface was measured by the aerial water drop method to obtain 10 degrees.

Heat mode printing was performed on the aluminum plate with the photocatalytic metal oxide thin film using the printer of Example 3 under the same conditions as in Example 3. Next, this plate was set on an Oliver 52 single-sided printing machine manufactured by Sakurai, the dampening water was purified water, and the ink was New Champion manufactured by Dainippon Ink and Chemicals, Inc.
500 sheets of offset printing were performed using F gloss 85 ink. From the start to the end, a clear printed matter with no stain on the non-image portion was obtained, and no damage to the printing plate was observed. Example 8 Next, the surface of this plate was soaked in a waste with a printing ink cleaning liquid Daiclean R (a sales agency; Dainippon Ink and Chemicals, Inc.) and washed carefully to remove the ink. Exposure was performed for 5 minutes at the same light intensity (25 mw / cm ² ) using the same light source as before (lighting device for baking manufactured by Ushio Inc.). When the contact angle of the surface was measured by a water drop method in the air, it was 10 degrees in the exposed area. Different heat mode printing was performed on this plate using the printer of Example 7 under the same conditions.

This plate was set on a single-sided printing press of Oliver 52 manufactured by Sakurai Co., and the dampening solution was purified with pure water, and the ink was prepared using Newchampion F gloss 85 ink manufactured by Dainippon Ink and Chemicals, Inc.
000 sheets of offset printing were performed. Clear prints were obtained from the start to the end, and no damage to the printing plate was observed. From these results, it was shown that the CsLa ₂ NbTi ₂ O ₁₀ photosensitive layer was also able to simplify the working process while maintaining the distinction between the ink receiving portion and the dampening solution holding portion, and was able to reuse the printing original plate by heat treatment. .

EXPERIMENTAL EXAMPLE 1 Using the sample of Example 1 having a barium titanate layer, the change in the contact angle before and after exposure and the increase rate of the contact angle when a heat treatment was applied to the sample whose contact angle was reduced by exposure were coordinated. Table 1 shows measured values obtained by the air-drop method using CONTACT-ANGLE METER CA-D manufactured by Interface Science Co., Ltd. From this table, it can be seen that the exposure causes a very significant change from hydrophobic to hydrophilic and that within 2 hours even at 130 ° C.
At 200 ° C. it is shown to return to the original hydrophobic surface in a few minutes. In drawing by strong heat mode light irradiation or thermal transfer, a higher temperature period can be obtained in a shorter time, so that it can be easily understood that hydrophilicity occurs quickly.

[0070]

[Table 1]

[0071]

The original printing plate of the present invention having a thin layer containing the above-mentioned photocatalytic metal oxide as a main component on the surface thereof becomes hydrophilic by irradiation with actinic light, and then converts photothermal energy such as infrared rays and laser beams. Printing screen is formed by irradiation of light or drawing in heat mode by contact with an electric heating medium, which makes it possible to perform offset printing that does not require a developing solution and maintains the clarity of the printing surface, and prints used The master can be made hydrophilic again by actinic light, regenerated, and used repeatedly.

Claims (4)

[Claims] 1. RTiO_Three(R is an alkaline earth metal source
Child), AB_2-xC_xD _3-xE_xO_Ten(A is a hydrogen atom or
Alkali metal atom, B is alkaline earth metal atom or lead source
, C is a rare earth atom, D belongs to Group 5A element of the periodic table
E is a metal atom also belonging to the group 4A element,
x represents any numerical value from 0 to 2), SnO_Two, Bi_TwoO
_ThreeAnd Fe_TwoO_ThreeA thin layer consisting of at least one of
Printing original plate was irradiated with actinic light.
After that, draw in heat mode and create a printing plate
The method of making a lithographic printing plate characterized by the following. 2. The method for preparing a lithographic printing plate according to claim 1, wherein after the ink remaining on the used printing plate surface is washed and removed, printing is repeatedly performed using the printing original plate. . 3. A method for preparing a lithographic printing plate according to claim 1, wherein the thin layer according to claim 1 is provided on a surface of the plate cylinder of the offset printing press on a printing surface side. 4. A lithographic printing original plate having a thin layer according to claim 1 on a surface on a printing surface side and used in the lithographic printing method according to claim 1.