JPH043864B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a waterless lithographic printing plate, and particularly to a waterless lithographic printing plate having excellent halftone dot reproducibility and developability. [Prior art] As a photosensitizer for waterless lithographic printing plates, ester compounds of O-naphthoquinonediazide sulfonic acid and phenol novolak resin are excellent in terms of photosensitivity, storage stability, etc., and several have been proposed in the past. . For example, JP-A-55-59466 discloses a waterless lithographic printing plate in which a silicone rubber layer is provided via an adhesive layer on a photo-solubilizable photosensitive layer made of an O-quinonediazide compound, which is lined with an aluminum plate. Disclosed. Furthermore, in JP-A-56-80046, a silicone rubber layer is provided on a photosensitive layer made of a partially esterified product of naphthoquinone-1,2-diazide-5-sulfonic acid chloride and phenol novolak resin crosslinked with a polyfunctional isocyanate. A waterless lithographic printing plate is disclosed. [Problems to be solved by the invention] These waterless planographic printing plates according to the prior art have the following problems:
There are the following problems in the plate making process. (1) When manually developing a large plate such as a Kikuzen plate, it takes a long time and work efficiency is extremely poor. (2) Manual development takes a long time, resulting in poor halftone dot reproducibility and easy scratches in non-image areas. (3) Due to poor developability, the processing speed of automatic processors is slow. In order to solve these problems, methods have been adopted to improve developing performance by improving developing solutions and developing brushes. For example, JP-A No. 58-35539 describes a method for improving developability using a developer consisting of hydrocarbons/polar solvent/water, and JP-A No. 58-159533 describes a developing brush with flocked threads of irregular cross-section. JP-A No. 60-28655 describes a method for improving developability in
A method of improving developability by adding an organic acid to a developer has been proposed. However, although these methods are effective in improving developability, they are still difficult to work with, and if the printing plate surface is rubbed with a developing brush for a long time or the printing plate is immersed in a developer for a long time, it will not be strong. The adhesion between the photosensitive layer and the silicone rubber layer, which should be bonded together to form a non-image area, is caused by the developer, and part of the non-image area may be removed, or the photosensitive layer that should remain may swell due to the developer. , and may be dissolved and removed during development, resulting in differences in image reproducibility depending on the length of development time. Furthermore, Japanese Patent Application Laid-Open No. 60-28656 proposes a method of image-wise exposing an image-forming laminate and then subjecting it to base treatment. Although this method has greatly expanded the development latitude, it is still insufficient to improve the developability. An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a waterless lithographic printing plate with excellent halftone dot reproducibility and developability. [Means for Solving the Problems] The present invention provides a waterless lithographic printing plate comprising a support, a photosensitive layer and a silicone rubber layer laminated in this order, wherein the photosensitive layer is represented by the following general formula (),
The present invention relates to a waterless lithographic printing plate characterized in that it is formed from a photosensitizer whose degree of esterification is 20% or more and 33% or less. Here, R: a portion is H, and the rest is an O-quinonediazide-containing group. R': H or an alkyl group or alkenyl group having 1 to 30 carbon atoms. n: An integer from 1 to 10. In the photosensitizer represented by the general formula () used in the present invention, R consists of H and an O-quinonediazide-containing group. Examples of the O-quinonediazide-containing group used in the present invention include 1,2-benzoquinonediazide sulfonyl and 1,2-naphthoquinonediazide sulfonyl. Further, the aromatic nucleus of the O-quinonediazide-containing group may have a substituent such as an alkyl group or an alkoxy group. In the present invention, the degree of esterification refers to the ratio of O-quinonediazide-containing groups in which a part of R in the above formula () is H and the rest is O-quinonediazide. It is important that the ratio of the O-quinonediazide-containing group to H is 20% or more and 33% or less/67% or more and less than 80%. If the degree of esterification in the above formula (), that is, the ratio of O-quinonediazide content, is less than 20%, the photosensitivity will be significantly reduced, and the solvent resistance of the unexposed photosensitive layer will be poor, resulting in poor image reproducibility. Become. On the other hand, if the degree of esterification is 34% or more, especially more than 35%, the development speed will drop significantly and the workability during plate making will deteriorate. In the present invention, the alkyl group represented by R' in formula () includes methyl, ethyl, propyl,
t-butyl, pentyl, hexyl, tridecyl,
Examples include tetradecyl, pentadecyl, hexadecyl, and stearyl groups. In addition, the alkenyl group represented by R' is 7
-Pentanedecenyl, 4,7-pentadecadienyl, 1,4,7-pentadecatrienyl, oleyl group, or two or more thereof. Specific examples of the photosensitizer used in the present invention include:
For example, novolak resin (phenol formaldehyde resin, cresol formaldehyde resin,
p-tert-butylphenol formaldehyde resin, phenol-modified xylene resin, or oak-modified phenol formaldehyde resin), an O-quinonediazide compound such as o-benzoquinonediazide, 1,2-naphthoquinone-1-diazide, 1,2-naphthoquinone- 2-Diazide, 7-
Methoxy-1,2-naphthoquinone-2-diazide, 6-chloro-1,2-naphthoquinone-2-diazide, 7-chloro-1,2-naphthoquinone-2
-diazide, 6-nitro-1,2-naphthoquinone-2-diazide, 5-(carboxymethyl)-1,
2-naphthoquinone-1-diazide, 3,3',4,
4'-diphenyl-bis-quinone-4,4'-diazide, 2,3-phenanthrenequinone-2-diazide, 9,10-phenanthrenequinone-10-diazide and 3,4-chrysenequinone-3- It is a polymer reaction product of an acid halide of quinone diazide such as diazide. Particularly preferred are
It is a 1,2-naphthoquinone diazide 5-sulfonic acid partial ester of phenol formaldehyde resin. In the waterless lithographic printing plate of the present invention, the above-mentioned photosensitizer is used alone, but there is no problem in combining it with other resins as a binder.
In addition, other components may be added to the photosensitive layer for the purpose of improving coating film formation and adhesion to the support within a range that does not impair the effects of the present invention, and dyes may be added to make the image visible during development. It is also possible to add. The degree of esterification of the photosensitizer in the waterless lithographic printing plate of the present invention is lower than the degree of esterification of the photosensitizer proposed in the past. Therefore, a drawback is that it is susceptible to effects such as halation from the substrate. In order to compensate for this drawback, it has been proposed to increase the thickness of the photosensitive layer or to provide an antihalation layer on the substrate as a support, but all of these formulations are economically disadvantageous. be. In the present invention, such drawbacks can be effectively overcome by adding a light absorber to the photosensitive layer. Here, the light absorbent to be added to the photosensitive layer has an absorption maximum between 300 nm and 450 nm in the ultraviolet/visible spectrum, and a molecular extinction coefficient of 200 to 40000 mol ^-1 at the maximum value. Those within this range are preferred. Specifically, salicylic acid ester-based, benzophenone-based, benzotriazole-based, nickel complex salt-based, azo compound-based light absorbers and the like may be mentioned. Among these light absorbers, benzophenone light absorbers are preferably used in terms of compatibility with the photosensitive layer. Particularly preferably, an aminobenzophenone represented by the following general formula (wherein R ₁ , R ₂ , R ₃ , and R ₄ are each hydrogen or an alkyl group having 4 or less carbon atoms). The thickness of the photosensitive layer provided on the support is approximately 0.1~
10 g/m ² is common. If it is too thin, coating properties tend to be a problem, while if it is too thick, it is economically disadvantageous. The support used in the present invention is preferably a dimensionally stable plate. Such items include:
These include those conventionally used as supports for printing plates, and they can be suitably used in the present invention. Such supports include paper, paper laminated with plastic (e.g. polyethylene, polypropylene, polystyrene, etc.), aluminum,
Metal plates such as zinc and steel, plastic films such as cellulose diacetate, cellulose triacetate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc., and laminated or vapor-deposited metals such as those mentioned above. This includes paper, plastic film, and elastic sheets such as rubber. It is also possible to further coat these supports to prevent halation and other purposes. The silicone rubber layer used in the present invention is mainly composed of a linear organic polysiloxane having a molecular weight of 1,000 to several hundreds of thousands and having the following repeating units. Here, n is an integer of 2 or more, R is an alkyl group, alkenyl group, or phenyl group having 1 to 10 carbon atoms, and preferably 60% or more of R is a methyl group. A crosslinking agent is added to this linear organopolysiloxane. Crosslinking agents used in so-called room temperature (low temperature) curing silicone rubber include acetoxysilane, ketoxime silane, alkoxysilane, aminosilane, etc., and are usually linear organic polysiloxanes with hydroxyl groups at the end. When combined, they become deacetated, oxime, alcoholized, deamined, and deamidated silicone rubbers, respectively. These silicone rubbers include
Furthermore, a small amount of an organic tin compound or the like is generally added as a catalyst. The appropriate thickness of the silicone rubber layer is about 0.5 to 100μ, preferably about 0.5 to 10μ; if it is too thin, it is economically disadvantageous, and if it is too thick, it is difficult to remove the silicone rubber layer during development. This results in a decrease in image reproducibility. In the lithographic printing plate of the present invention, adhesion between the support and the photosensitive layer, and between the photosensitive layer and the silicone rubber layer is very important for basic plate performance such as image reproducibility and printing durability, so it is necessary to Accordingly, it is possible to provide an adhesive layer between each layer or to add an adhesion-improving component to each layer. In particular, for adhesion between the photosensitive layer and the silicone rubber layer, it is effective to provide a known silicone primer or silane coupling agent layer between the layers, or to add a silicone primer or silane coupling agent to the silicone rubber layer or photosensitive layer. . In particular, silane coupling agents, especially aminosilanes, are preferably used. In order to protect the silicone rubber layer forming the surface of the waterless lithographic printing plate constructed as described above, a thin protective film may be laminated on the surface of the silicone rubber layer. The waterless lithographic printing plate according to the present invention as described above is manufactured, 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 coater 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 thereon in the same manner, and heat-treat for several minutes, usually at a temperature of 100 to 120°C. and sufficiently cured to form a silicone rubber layer. If necessary, cover the silicone rubber layer with a protective film using a laminator or the like. The thus produced waterless lithographic printing plate of the present invention is exposed to actinic light through, for example, a negative film sealed in vacuum. The light source used in this exposure step is one that generates abundant ultraviolet light, and can be a mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, or the like. After exposure, the protective film is removed from the exposed printing plate, if necessary, and the plate is immersed in a developer and developed using a developer pad or a developer brush. As the developer used in the present invention, those commonly proposed for waterless lithographic printing plates can be used. For example, aliphatic hydrocarbons (hexane, heptane, gasoline, kerosene, etc.), aromatic hydrocarbons (toluene, xylene, etc.), or halogenated hydrocarbons (triclene, etc.) that can swell silicone rubber are combined with the following polar solvents. It is preferable to add . Alcohols (methanol, ethanol, etc.) Ethers (ethyl cellosolve, ethyl carbitol, butyl carbitol, dioxane, etc.) Ketones (acetone, methyl ethyl ketone, etc.) Esters (cellosolve acetate, carbitol acetate, etc.) Amines (ethanolamine, 2 -ethylaminoethanol, pendylamine, etc.) In the present invention, the degree of esterification is determined by elemental analysis using an elemental analyzer CHN coder MT-3 model manufactured by Yanagimoto Seisakusho. [Example] The present invention will be explained in more detail with reference to Examples below. Example 1 The following primer composition was applied to an aluminum plate (manufactured by Sumitomo Light Metal Co., Ltd.) with a thickness of 0.3 mm, and heat treated at 200° C. for 2 minutes to form a 5 μm thick primer layer. (1) Polyurethane resin (Sample LQ-T1331,
Sanyo Chemical Industries, Ltd.) 100 parts by weight (2) Blocked isocyanate (Takenate B830,
Takeda Pharmaceutical Co., Ltd.) 20 parts by weight (3) Epoxy/phenol/urea resin (SJ9372,
(manufactured by Kansai Paint Co., Ltd.) 8 parts by weight (4) Dimethylformamide 725 parts by weight Subsequently, the following photosensitive composition was coated on this using a bar coater, and dried for 1 minute in hot air at 110°C to determine the thickness. A 2μ photosensitive layer was provided. (1) Naphthoquinone-1,2-diazide-5-sulfonic acid and phenol formaldehyde novolak resin (manufactured by Sumitomo Durez: Sumilight Resin)
PR50622) partial ester (degree of esterification 25% by elemental analysis) 100 parts by weight (2) 4,4'-diphenylmethane diisocyanate
40 parts by weight (3) Dibutyltin diacetate 0.2 parts by weight (4) 4,4'-diethylaminobenzophenone
5 parts by weight (5) 800 parts by weight of tetrahydrofuran Next, a silicone rubber layer having the following composition was coated on the photosensitive layer using a bar coater, and heated and cured for 3 minutes at 115°C with a dew point of 30°C to a thickness of 2.5μ. A silicone rubber layer was provided. (1) Polydimethylsiloxane (molecular weight approximately 25,000,
(terminal OH group) 100 parts by weight (2) Vinyltri(methylethylketoxime)silane 8 parts by weight (3) Dibutyltin diacetate 0.1 part by weight (4) γ-Aminopropyltrimethoxysilane
0.5 parts by weight (5) “Isopar” E (manufactured by Exxon Chemical Co., Ltd.)
1400 parts by weight Add a layer of 10μ thick to the laminate obtained as above.
polypropylene film “Torefane” (Toray Industries, Ltd.)
Co., Ltd.) was laminated using a calendar roller to obtain a waterless lithographic printing original plate. A metal halide lamp (Idol Fin 2000, manufactured by Iwasaki Electric Co., Ltd.) was used on the original printing plate, and a UV meter (manufactured by Oak Seisakusho, light measure type) was used.
UV-402A) with an illuminance of 11 mW/cm ² for 6 full-surface exposures.
It was applied for seconds. A negative film having a halftone image of 150 lines/inch was vacuum-adhered onto the printing original plate obtained as described above, and was exposed for 60 seconds from a distance of 1 m using the metal halide lamp described above. Next, the above "Trejuan" was peeled off and soaked in a pre-treatment liquid ("Isopar" H (manufactured by Exxon Chemical Co., Ltd.)/butyl carbitol/ethyl cellosolve/monoethanolamine = 90/10/5/0.6 weight ratio). Wet the exposed plate completely and process for 1 minute. Remove the pre-treatment liquid on the plate surface with a rubber squeegee, then apply developer (butyl carbitol/
When water/2-ethylbutyric acid/crystal violet (20/80/2/0.2 weight ratio) is poured and the plate surface is lightly rubbed with a developing pad, the silicone rubber layer in the imagewise exposed areas is removed and the surface of the photosensitive layer is removed. was exposed. On the other hand, the silicone rubber layer remained firmly in the exposed area, and an image that faithfully reproduced the negative film was obtained. The time from the start of rubbing with the developing pad until the printing plate was completed (hereinafter simply referred to as developing time) was 1.5 minutes. This printing plate was attached to an offset printing machine (Komori Sprint 2 Color) and printed using Toyo Ink Co., Ltd.'s "Aquares" ST indigo without using dampening water, with a halftone dot of 3% at 150 lines/inch. Prints with very good images with ~95% reproduction were obtained. Even after printing 50,000 copies, no scumming or damage to the plate surface was observed, and printing could continue. Printed image reproducibility also remained unchanged throughout the printing period. Comparative Examples 1 to 10, Examples 2 to 7 Printing was carried out in the same manner as in Example 1 using naphthoquinone-1,2-diazide-5-sulfonic acid esters of phenol novolac resins having different degrees of esterification as shown in Table 1. A version was created. The obtained printing plate was irradiated for 60 seconds from a distance of 1 m using a metal halide lamp through a negative film having a halftone image of 150 lines/inch. Using the pretreatment solution and developer used in Example 1, the Kikuzen plate was developed by hand. This printing plate was attached to an offset printing machine, and printing was performed using "Aquares" ST indigo manufactured by Toyo Ink Co., Ltd. to evaluate halftone dot reproducibility. Table 1 shows the time required for hand development and the results of halftone reproducibility. In Comparative Example 1, the required development time was short, but
Poor halftone reproducibility (especially in shadow areas). In addition, Comparative Examples 2 to 4 and 9 have good halftone reproducibility, but
The required development time was long and scratches appeared in non-image areas. In Examples 2 to 4, the required development time was 2 to 3 minutes, and the halftone dot reproducibility was also good. In addition, in Table 2, the plates used in Table 1 were manufactured using a Toray waterless lithographic automatic developing machine (TWL-1160, Toray Industries, Inc.).
The results of evaluating halftone dot reproducibility by changing the conveyance speed are shown below. In Comparative Example 5, the reproducibility of shadow portions is poor when the conveyance speed is slow. Moreover, in Comparative Examples 6 to 8 and 10, the reproducibility of the highlight portion is poor when the conveyance speed is high (60 to 80 cm/min).
Moreover, in Comparative Examples 6 to 8, the reproducibility of the highlighted portion was particularly poor when the conveyance speed was high (60 to 80 cm/min).
In Examples 5 and 6, the conveyance speed was 20 to 80
Shows good halftone reproducibility in cm/min.

【table】

【table】

[Table] Example 8 Naphthoquinone-1,2-diazide of phenol novolac resin (Sumitomo Durez Co., Ltd.: Sumilite Resin PR50622) with a degree of esterification of 25% was applied to a chemically treated aluminum plate (manufactured by Sumitomo Light Metal Co., Ltd.) 7 of -5-sulfonic acid ester (degree of esterification determined from elemental analysis)
After spin coating the wt% dioxane solution with Whaler,
It was dried at 100°C for 3 minutes to form a 2.7μ photosensitive layer. On top of this, a 0.2% by weight "Isopar" E solution of γ-aminopropyltriethoxysilane (UCC: A1100) was spin-coated using a Whaler, and then heated at 110℃ for 1 hour.
Dry for a minute. A 7% "Isopar" E solution of a silicone composition having the following composition was applied onto this by spin coating using a Whaler, and then heated and cured at 120 DEG C. for 4 minutes. The thickness of the silicone rubber layer obtained in this case was 2.2μ. (1) Polydimethylsiloxane (molecular weight: approx. 80,000, terminal OH group) 100 parts by weight (2) Ethyltriacetoxysilane 8 parts by weight (3) Dibutyltin diacetate 0.2 parts by weight Vacuum-adhered to the printing original plate obtained as above. Using a metal halide lamp (Idolfin 2000, manufactured by Iwasaki Electric Co., Ltd.), a negative film with a dot image of 150 lines/inch was passed through, and 60
Irradiated for seconds. Ethanol/“isopar” plate surface
When immersed in E (20/80 weight ratio) and rubbed lightly with a developing pad, the exposed areas were easily removed and the chemically treated aluminum surface was exposed, while the unexposed areas had a strong silicone rubber layer remaining. , an image that faithfully reproduced the negative film was obtained. This printing plate was attached to an offset printing machine (Komori Sprint 2 Color) in the same way as in Example 1.
When printed using "Aquares" ST indigo manufactured by Toyo Ink Co., Ltd., 20,000 copies of printed matter with extremely good images, with 5 to 95% of halftone dots reproduced at 150 lines/inch, were printed. Example 9 On a composite substrate in which a chloroprene rubber layer with a thickness of 0.3 mm and a rubber hardness of 60 (Shore A) was provided on an aluminum plate with a thickness of 0.3 mm, naphthoquinone-1, a phenol novolac resin with a degree of esterification of 33%, A 20% by weight solution of 2-diazide-5-sulfonic acid ester in ethyl cellosolve was applied using a bar coater, and then dried at 110°C for 2 minutes to form a photosensitive layer with a thickness of 3 μm. A 0.5% "Isopar" E solution of γ-aminopropyltrimethoxysilane (manufactured by Chitsuso Corporation: A0800) was applied onto this by spinning using a Whaler, and then dried at 110° C. for 1 minute. A 10% by weight "Isopar" E solution of the same silicone composition used in Example 8 was applied onto this by spin coating using a Whaler, and then heated and cured at 120 DEG C. for 4 minutes. The printing plate obtained as described above was passed through a negative film and exposed to light for 60 seconds from a distance of 1 m using a metal halide lamp. Ethanol/
When the plate surface is wetted with a developer consisting of "Isopar" E/water (65/35/3 weight ratio) and rubbed lightly with a developer pad, the image-exposed area is easily removed and the rubber layer of the substrate is exposed; A printing plate was obtained in which the silicone rubber layer remained firmly in the unexposed areas and faithfully reproduced the negative film. Example 10 The following photosensitive composition was coated on a 150μ thick polyester film (“Lumirror” manufactured by Toray Industries, Inc.) using a bar coater, and dried for 1 minute in hot air at 115°C to form a 2μ thick photosensitive layer. has been established. (1) Naphthoquinone-1,2-diazide-5-sulfonic acid and phenol formaldehyde novolac resin (manufactured by Sumitomo Durez Co., Ltd.: Sumilight Resin
PR50622) partial ester (degree of esterification 25
%) 100 parts by weight (2) 4,4'-diphenylmethane diisocyanate
30 parts by weight (3) 0.2 parts by weight of dibutyltin dilaurate (4) 0.8 parts by weight of p-toluenesulfonic acid (5) 800 parts by weight of tetrahydrofuran The same silicone rubber composition as used in Example 1 was then applied on top of this photosensitive layer. After spin coating with Whaler, heat cure for 3 minutes at 120℃, dew point 30℃,
A silicone rubber layer with a thickness of 2.5μ was provided. The entire surface of the printing plate obtained as described above was exposed for 6 seconds at an illumination intensity of 11 mW/cm ² using the UV meter used in Example 1 using a metal halide lamp. The printing original plate thus obtained was exposed to light from a distance of 1 m for 60 seconds using a metal halide lamp through a negative film having a halftone image of 150 lines/inch which was vacuum-adhered. Then, the plate was immersed in a pre-treatment liquid "Isopar" H/butyl carbitol/ethyl cellosolve/monoethanolamine (90/10/5/1 weight ratio) to completely wet the exposed plate and treated for 1 minute. Remove the pretreatment liquid on the plate surface with a rubber squeegee, and then apply developer (butyl carbitol/water/2-ethylbutyric acid/crystal violet = 30/70/2/0.2 weight ratio) to the development pad.
When the plate surface was lightly rubbed with a developing pad, the silicone rubber layer on the exposed portion of the image was removed and the surface of the photosensitive layer was exposed. On the other hand, the silicone rubber layer remained firmly in the exposed area, and an image that faithfully reproduced the negative film was obtained. Example 11 Naphthoquinone-1,2 as described in Example 1
-Table of partial esters of diazide-5-sulfonic acid and phenol formaldehyde novolak resin-
A waterless lithographic printing original plate shown below was obtained in the same manner except for the following changes. When such a waterless lithographic printing plate is exposed entirely to light in the same manner as in Example 1, and then, after image exposure, it is immersed in a pretreatment solution for 1 minute and developed. As shown in Table 3, the required development time is short, and A printing plate with good halftone reproducibility was obtained.

〔Effect of the invention〕

According to the waterless lithographic printing plate of the present invention, the following effects are achieved. (1) When manually developing a large plate such as a Kikuzen plate, the time required is shortened, so work efficiency is significantly improved. (2) The short development time prevents scratches on the silicone rubber layer in non-image areas. (3) Since the developability is improved, the processing speed of automatic processors can be increased, and work efficiency is improved.

Claims (1)

[Claims] 1. A waterless lithographic printing plate comprising a support, a photosensitive layer and a silicone rubber layer laminated in this order,
A waterless lithographic printing plate, characterized in that the photosensitive layer is formed of a photosensitive agent represented by the following general formula () and whose degree of esterification is 20% or more and 33% or less. Here, R: a portion is H, and the rest is an O-quinonediazide-containing group. R': H or an alkyl group or alkenyl group having 1 to 30 carbon atoms. n: An integer from 1 to 10.