JPH01158451A - Production of waterless planographic printing plate - Google Patents

Abstract

PURPOSE:To permit utilization of a waterless planographic printing plate for negative working as the printing plate for positive working as well by using a light source which has no transparent plate for shielding UV rays on the plate surface and projecting active rays contg. UV rays of a specific wavelength to the printing plate. CONSTITUTION:A planographic printing master disk is subjected to image exposing by using the light source having no transparent plate for shielding UV rays and projecting the active rays contg. the UV rays of <=350nm wavelength through, for example, a positive film which is brought into tight contact by a vacuum with the plate to said plate in the case of using the waterless planographic printing plate as the printing plate for positive working. The silicone rubber layer in the part subjected to the photoirradiation by this image exposing treatment remains at the time of development and the silicone rubber layer in the nonirradiated part exfoliates and dislodges. The easy use of the printing master plate for negative working as the printing plate for positive working is thereby enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for making a waterless lithographic printing plate that allows printing without dampening water.

[Prior Art] Waterless lithographic printing is basically a method in which a printed area and a non-printed area are made to exist on almost the same plane, with the printed area made to be ink-receptive and the non-printed part to be ink-repellent. In the lithographic printing method, which takes advantage of the difference in ink adhesion to apply ink only to the image area, and then transfers the ink to a printing medium such as paper, the non-image area is made of silicone. Refers to a printing method that consists of a layer of a material that is ink repellent, such as rubber or a fluorine-containing compound, and that allows printing without using dampening water.

By the way, waterless lithographic printing plates that have excellent practical performance include those that utilize a silicone rubber layer as an ink-repellent material layer, for example, for positive working, Special Public Service 1977-
26923, and for negative working, JP-A-55-59466 and JP-A-56-80046.
and so on. In particular, Japanese Patent Application Laid-Open No. 56-80046 can be said to describe a plate construction having high practical performance for negative working.

The printing plate proposed here is a presensitized lithographic printing plate having a silicone rubber layer provided on a light-repellent photosensitive layer backed by a support. In the waterless lithographic printing plates proposed in JP-A-55-59466 and JP-A-56-80046, a photosensitive layer containing a quinonediazide compound, which is particularly preferably used, has a light-sensitive layer in the exposed area during normal exposure. Since the quinone diazide in the layer changes to indene carboxylic acid, by developing with a developer, the silicone Baum layer in the exposed area is peeled off or the entire photosensitive layer is removed. As a result, a printing plate with a negative pattern is formed in which the photosensitive layer or substrate in the exposed areas is exposed and the unexposed areas are covered with a silicone rubber layer.

By the way, this printing plate for negative working has no problems in normal exposure processing and can be put to practical use. It has been found that if the film is exposed to light with the film removed (e.g.), development becomes impossible (the silicone rubber layer in the exposed area does not peel off or the photosensitive layer in the exposed area does not dissolve).

As a result of intensive research into the analysis of this unique phenomenon, we have discovered that this phenomenon can be applied to a plate-making method for waterless lithographic printing plates, and have thus arrived at the present invention.

[Problems to be Solved by the Invention] Accordingly, an object of the present invention is to provide an effective and simple plate-making method that allows a waterless lithographic printing plate for negative working to be used also for positive working.

[Means for Solving the Problems] The present invention provides that when a waterless lithographic printing plate in which a photosensitive layer containing a quinone diazide compound and an ink repellent layer are successively laminated on a substrate is imagewise exposed, the plate surface is provided with an ultraviolet light shielding layer. This is a plate-making method for a waterless lithographic printing plate for positive working, characterized in that an image is formed by irradiating actinic light containing ultraviolet rays with a wavelength of 350 nm or less using a light source without a transparent plate.

The photosensitive layer referred to in the present invention is composed of a substance containing a known quinonediazide structure, and the substance containing a quinonediazide structure is the one normally used in positive-working PS plates, Wipon plates, photoresists, etc. They are quinonediazides.

Examples of such quinonediazides include esters of benzoquinone-1,2-diazide-4- or -5-sulfonic acid and polyhydroxyphenyl, naphthoquinone-1
, ester of 2-diazide-4- or -5-sulfonic acid and pyrogallolacetone resin, naphthoquinone-1,
Esters of 2-diazide-4- or -5-sulfonic acid and phenol formaldehyde novolac resins or cashew-modified novolak resins may be mentioned. Also, low molecular weight quinonediazide compounds (e.g. naphthoquinone-1,
esters of 2-diazide-5-sulfonic acid with phenol, cresol, xylenol, catechol, pyrogallol, bisphenol A, etc.) or novolac resins that do not contain photosensitive groups in the resins containing the above quinone diazide groups (e.g., phenol , soluble fusible resins obtained by condensing phenols such as cresol, xylenol, catechol, and pyrogallol with formaldehyde in the presence of an acidic catalyst) may be simply mixed. A photoreleasable photosensitive layer in which quinone diazides are crosslinked with a polyfunctional compound as proposed in JP-A-56-80046 can be mentioned.

As a crosslinking agent, polyfunctional isocyanates such as paraphenylene diisocyanate, 2,4- or 2,6-
-tolylene diisocyanate, 4,4°-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, or adducts thereof, or polyfunctional epoxy compounds, such as,
Examples include polyethylene glycol diglycidyl ethers, polypropylene glycol diglycidyl ethers, bisphenol A diglycidyl ether, and trimethylolpropane triglycidyl ether. These thermal curing temperatures are within a range that does not cause loss of photosensitivity of the photosensitive material, usually 13
It is preferable to carry out the reaction at a temperature of 0° C. or lower, and therefore a catalyst or the like is usually used in combination.

In addition, methods for modifying quinonediazides by reacting them with monofunctional compounds to make them poorly soluble or insoluble in developing solutions include esterifying, amidating, or urethanizing the active groups of the quinonediazides. Can be mentioned. The compound to be reacted with the active group of the quinonediazide may be a low-molecular compound or a relatively high-molecular compound, or may be obtained by craft polymerizing the quinonediazide with Natsuma.

Particularly preferable photosensitive layers for use in the present invention are:
It is obtained by crosslinking or modifying a partially esterified product of naphthoquinone-1,2-diazide-5-sulfonic acid and phenol formaldehyde novolak resin with a polyfunctional or monofunctional isocyanate.

The thickness of the photosensitive layer is about 0.1-100μ, preferably about 0.1μ.
5 to 10μ is appropriate. If it is too thin, defects such as pinholes are likely to occur during coating, while if it is too thick, it is disadvantageous from an economic standpoint.

Further, it is possible to add other components to the photosensitive layer for the purpose of improving coating film forming properties and adhesion to the support within a range that does not impair the effects of the present invention.

Examples of the ink-repellent layer used in the present invention include silicone rubber and fluorine-containing compounds (for example, rubbers containing fluorine in the molecule), and silicone rubber is particularly preferably used. Such a silicone rubber layer is preferably one whose main component is a linear organic polysiloxane having the following repeating units and a molecular weight of several thousand to several hundred thousand.

Here, n is an integer of 2 or more, R and R' are an alkyl group, an alkenyl group, or a phenyl group having 1 to 10 carbon atoms,
Preferably, 60% or more of R and R' are methyl groups.

A crosslinking agent is usually added to this linear organic polysiloxane. Examples of crosslinking agents used in so-called room temperature (low temperature) curing silicone rubber include acetoxysilane,
There are ketooxime silanes, alkoxysilanes, aminosilanes, amidosilanes, etc., which are usually used in combination with linear organic polysiloxanes with hydroxyl groups at the ends, to produce acetic acid-removed type, oxime-eliminated type, alcohol-eliminated type, deamined type, and deamidated type, respectively. It becomes the silicone rubber of the mold. A small amount of an organic tin compound or the like may be added as a catalyst to these silicone rubbers.

The appropriate thickness of the silicone rubber layer is approximately 0.5 to 100μ, preferably approximately 0.5 to 10μ; if it is too thin, problems may occur in terms of printing durability; on the other hand, if it is too thick, This is not only economically disadvantageous, but also makes it difficult to remove the silicone rubber layer during development, resulting in a decrease in image reproducibility.

In the printing plate used in the present invention, a support, a photosensitive layer,
Adhesion between the photosensitive layer and the silicone rubber layer is very important for basic plate performance such as image reproducibility and printing durability, so if necessary, an adhesive layer may be provided between each layer or It is possible to add adhesion-improving components.In particular, to improve the adhesion between the photosensitive layer and the silicone rubber layer, a known silicone primer or silane coupling agent layer may be provided between the photosensitive layer and the silicone rubber layer, or a silicone rubber layer or It is effective to add a silicone primer or a silane coupling agent to the photosensitive layer.

The substrate of the lithographic printing original plate used in the present invention must be flexible enough to be attached to a normal lithographic printing machine and must be able to withstand the load applied during printing. Typical examples include metal plates such as aluminum, copper, and iron, plastic films such as polyester film and polypropylene film, coated paper, and rubber.

The substrate may be a composite of these. Moreover, it is also possible to further apply a coating or the like on these substrates for the purpose of preventing halation or the like.

A protective film may be laminated on the surface of the silicone rubber layer side of the waterless lithographic printing original plate constructed as described above for the purpose of protecting the silicone rubber layer, to the extent that the effects of the present invention are not impaired. is also possible.

The waterless lithographic printing original plate used in the present invention is produced, for example, as follows. First, a composition solution to form a photosensitive layer is applied onto a support using a normal coater such as a reverse roll coater, an air knife coater, a Meyer bar coater, or a rotary coating device such as a Whaler, and then dried and coated as necessary. After heat curing, if necessary, apply an adhesive layer on the photosensitive layer in the same manner, and after drying, apply a silicone rubber solution on the photosensitive layer or the adhesive layer in the same manner,
It is usually heat treated at a temperature of 50 to 130° C. for several minutes to fully cure and form a silicone rubber layer. If necessary, cover the silicone rubber layer with a protective film using a laminator or the like.

Next, a plate-making method using exposure processing proposed in the present invention will be explained. That is, when the above-mentioned waterless lithographic printing original plate is used for positive working, the lithographic printing original plate is passed through, for example, a vacuum-adhesive positive film, and is heated at a distance of 3500 m or less using a light source that does not have a transparent plate for blocking ultraviolet rays. Image exposure is carried out by irradiation with actinic light including ultraviolet rays of the same wavelength. By this image exposure process, the silicone rubber layer in the light-irradiated areas remains during development, and the silicone rubber layer in the non-light-irradiated areas peels off.

The light source used for this exposure process is basically not restricted as long as it contains ultraviolet rays with a wavelength of 350 nm or less, and commonly used high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, xenon lamps, and carbon arc lamps. A laser that emits a single wavelength of 350 nllI or less can be used. However, in the case of a normal exposure light source, a transparent plate for blocking ultraviolet rays is provided between the light source and the printing original plate, so the amount of ultraviolet rays with a wavelength of 350 nm or less that can reach the surface of the printing original plate is extremely small. It is not possible to express the effect of For example, a high pressure mercury lamp is 314,
It has an emission line spectrum of 335.365.436.546.578 nm as the main emission peak, but 314 nm
．． The emission peak at 335 nm is almost completely blocked by the glass that cuts the short wavelength ultraviolet rays mentioned above, that is, the ultraviolet ray shielding transparent plate between the light source and the printing plate, and does not reach the surface of the printing plate. I can't.

Therefore, in order to effectively exhibit the effects of the present invention, it is necessary to devise ways to abundantly irradiate the surface of the printing original plate with ultraviolet rays having a wavelength of 350 nm or less. That is, in the present invention, it is necessary to remove the ultraviolet ray shielding transparent plate from between the light source and the original printing plate to allow light with wavelengths of 314 and 335 nm to effectively reach the surface of the printing plate. to the light source itself,
No matter how much ultraviolet rays with a wavelength of 350 nm or less are included, if there is a glass plate or the like between the light source and the surface of the printing plate that blocks the ultraviolet rays on the short wavelength side, the effect will be difficult to manifest, and the exposed area will be The silicone rubber layer is removed to form a normal negative working pattern, but by removing these glass plates, it is possible to increase the amount of ultraviolet light in the wavelength range that reaches the surface of the original printing plate.

In addition, when exposing with a laser that oscillates a single wavelength of 350 nm or less (for example, an excimer laser), monochromatic light of a specific wavelength can be specified, so compared to the exposure light source that has a wavelength distribution of long and short wavelengths, the present invention Easily produces effects. That is, it is advantageous for the effect of the present invention to be achieved if the amount of unnecessary long-wavelength (wavelength exceeding 350 nm) light rays reaching the surface of the original printing plate is small. The amount of irradiation light required to achieve the effects of the present invention varies depending on the type of light source and the intensity of irradiation light, but it is usually 35Qnm.
A light source that irradiates abundant ultraviolet rays with the following wavelengths exhibits its effect in a shorter irradiation time. For example, if a general high-pressure mercury lamp (3KW, manufactured by Oak Seisakusho, [Jet Light 3300J]) is used as the light source for exposure,
Remove the UV-blocking transparent plate (glass plate) between the light source and the original printing plate, and install a UV meter (newly manufactured by Oak Manufacturing Co., Ltd., UV-
302A> at an illumination intensity of 3.5 mW/ri for 10 seconds or more, preferably 20 seconds or more, actinic rays with a wavelength of 350 nllll or less, which can fully exhibit the effects of the present invention, can be obtained. When the amount of actinic rays is less than this, the effect of the present invention rapidly disappears, and the film begins to exhibit normal negative working behavior (the silicone rubber layer in the exposed area peels off during development).

In addition, in order to express the effects of the present invention more effectively,
After the image exposure is completed and before the development process is performed, the entire plate surface may be exposed to light using a normal light source as described below. Exposure using a normal light source as used herein means exposure to active light that does not substantially contain ultraviolet rays with a wavelength of 350 nm or less. For example, in the case of a high-pressure mercury lamp, ultraviolet rays with a wavelength of 350 nm or less are blocked by a transparent plate for blocking ultraviolet rays. This corresponds to when used as

Due to this exposure of the other side of the printing plate, which is performed separately from image exposure, the non-irradiated areas during image exposure are irradiated with ultraviolet rays with a wavelength exceeding 350 nm, and the non-irradiated areas are not irradiated with light at all. The silicone rubber layer can be peeled off more easily and more reliably than when the silicone rubber layer is developed without being developed.

When the surface of the exposed plate is rubbed with a developing pad containing a developer, the silicone rubber layer in the unexposed areas is removed and the ink receiving areas are exposed. If the photosensitive layer is not crosslinked or modified, part or all of its thickness will fall off during the development process, and the exposed surface will become an ink receiving area after the development process. In addition, in the case of a photosensitive layer that has been made insoluble in a developer by crosslinking or modification, it remains without substantially reducing its thickness, and the exposed surface of the photosensitive layer is ink receptive. Becomes a department. The developer used in the present invention is preferably one that dissolves or swells the photosensitive layer.

Specific examples of the developer include the following.

Alcohols (methanol, ethanol, etc.) Ethers (methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carpitol ethyl carpitol xane, tetrahydrofuran, etc.) Ketones (acetone, methyl ethyl ketone, etc.) Esters (ethyl acetate, butyl acetate, methyl cellosolve acetate) , ethyl cellosolve acetate, ethyl carpitol acetate, etc.) Into the above polar solvent, add a hydrocarbon that swells the silicone rubber layer (hexane, heptane, ``isopar'' E,)-1,G (Esso product) or gasoline, volatile oil, kerosene, etc.) or halogenated hydrocarbons (triclene, etc.).Water may be added if necessary.Dye may also be added to dye the image area from which the silicone rubber layer has been removed. You may.

[Example] EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 The following primer composition was applied to an aluminum plate (manufactured by Sumitomo Light Metals (II)) with a thickness Q of 3 mm, and heat treated at 200° C. for 2 minutes to form a 5 μm thick primer layer.

■Polyurethane resin (Sunbren LQ-T1331, manufactured by Sanyo Chemical Industries (11) > 100 parts by weight ■Blocked isocyanate (Takenate 8830, manufactured by Takeda Pharmaceutical V/J) 20 parts by weight ■Epoxy, phenol,
Urea resin (SJ9372, manufactured by Kansai Paint ■)
8 parts by weight 725 parts by weight of dimethylformamide Subsequently, the following photosensitive layer composition was coated thereon using a bar coater and dried for 1 minute in hot air at 110 DEG C. to form a photosensitive layer with a thickness of 2 .mu.m.

■Partial ester of naphthoquinone-1,2-diazide-5-sulfonic acid and phenol formaldehyde novolac resin (Nisumilite Resin PR50622 manufactured by Sumitomo Durez) (degree of esterification 25% by elemental analysis)
100 parts by weight 40 parts by weight of 4,4-diphenylmethane diisocyanate ■ 0.2 parts by weight of dibdeltin diacetate ■ 5 parts by weight of 4,4°-diethylaminobenzophenone ■ 0.8 parts by weight of p-toluenesulfonic acid ■ 800 parts by weight of tetrahydrofuran Then, after spin-coating a silicone rubber composition having the following composition on this photosensitive layer,
115℃, dew point 30℃, moist heat curing for 3.5 minutes 2
．． A 3μ silicone rubber layer was provided.

■Polydimethylsiloxane (molecular weight approx. 25.0001 terminal OH group> 100 parts by weight ■Vinyl tri(methyl ethyl ketoxime) silane
8 parts by weight ■ 0.1 parts by weight of dibutyltin diacetate ■ 0.5 parts by weight of γ-aminopropyltrimethoxysilane ■ 1400 parts by weight (Isopar (manufactured by Exxon Chemical)) 4 parts by weight Laminated layer obtained as above A 10 μm thick polypropylene film “Torefane” (manufactured by Bunshii ■) was laminated on the plate using a calendar roller to obtain a waterless lithographic printing original plate.

A high-pressure mercury lamp (3KW: Newly manufactured by Oak Seisakusho [Jet Light 3300J)] is used for the printing original plate, and the glass plate between the light source and the printing original plate is removed to emit short wavelength ultraviolet rays (
The luminescence peak at 314, 335 stops) reaches the surface of the original printing plate unobstructed.
Image exposure was performed for 15 seconds at an illumination intensity of 3.5 mW/i using a new model manufactured by Oak Manufacturing Co., Ltd., LJV302A>. (A positive film with a halftone image of 150 lines/inch was used.) Next, the 'Trephan' was peeled off, and a hand development pad used in waterless lithographic printing was used, and ethyl cellosolve was used as the developer. Development was performed.As a result, the silicone rubber layer in the image-exposed areas was firmly adhered to the photosensitive layer, while in the unexposed areas, the silicone rubber layer fell off and the surface of the photosensitive layer was exposed.This is a positive working printing. A version was obtained.

Example 2 A printing original plate similar to that in Example 1 was imagewise exposed using the same light source. Thereafter, the entire surface of the printing plate was exposed to light for 30 seconds under normal usage conditions, that is, under a condition where a protective glass was present between the original printing plate and the light source.

Next, "Trephan" was peeled off, and development was carried out using a hand development pad used in waterless lithography using ethyl cellosolve and water/ethanol=50150 (weight ratio) as developers. As a result, when using water/ethanol as in the case of ethyl cellosolve, development was easy and a positive working printing plate with good image reproducibility was obtained.

Comparative Example 1 A printing original plate similar to that in Example 1 was used under normal usage conditions, that is, a situation in which a protective glass or a baking frame glass was present between the printing original plate and the light source, using the same light source. Image exposure was performed using film. When the same development was then carried out, the silicone rubber layer fell off in both the foggy and unexposed areas. When the developer was changed to a mixture of ethanol/Isopar E (1:1 weight ratio) and development was carried out, the silicone rubber layer in the exposed areas fell off, and the silicone rubber layer in the unexposed areas adhered to the photosensitive layer. A printing plate for negative working that remained intact was obtained.

[Effects of the Invention] The exposure and development method according to the present invention allows a printing original plate for negative working to be easily used as a printing plate for positive working.

Claims (1)

[Claims] a photosensitive layer containing a quinonediazide compound on the substrate;
When imagewise exposing a waterless lithographic printing plate in which ink-repellent layers are sequentially laminated, the plate surface is irradiated with actinic rays containing ultraviolet rays with a wavelength of 350 nm or less using a light source that does not have a transparent plate for blocking ultraviolet rays. A method for making a waterless lithographic printing plate for positive working, which is characterized by forming an image.