JP2001219526A - Method for repairing defect of photosensitive resin plate having infrared sensitive layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for regenerating a photosensitive resin plate by removing an infrared sensitive layer regardless of the kind of the binder polymer of the infrared sensitive layer without taking labor and applying dust to a photosensitive resin layer or damaging the layer when the infrared sensitive layer must be removed and reformed to perform repairing at a time when the failure of the formation of the infrared sensitive layer is generated by the adhesion of foreign matter to the surface of the photosensitive resin layer or the infrared sensitive layer is damaged after formation in a process for forming the infrared sensitive layer on the surface of the photosensitive resin layer at a time of the production of a flexographic printing plate corresponding to a plate making process for directly drawing an image becoming digital data using infrared laser without using a negative film. SOLUTION: The infrared sensitive layer formed by direct drawing using infrared laser is removed from the photosensitive resin layer having the infrared sensitive layer formed on its surface and, thereafter, the infrared sensitive layer is reformed to regenerate the photosensitive resin plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a flexographic printing plate corresponding to a plate making process for directly drawing an image which has become digital information using an infrared laser without using a negative film. In the process of forming the infrared-sensitive layer on the surface of the resin, the infrared-sensitive layer is repaired, for example, when the formation of the infrared-sensitive layer has failed due to the attachment of foreign matter to the photosensitive resin surface or the formed infrared-sensitive layer has been damaged. The present invention relates to a method for regenerating a photosensitive resin plate by removing an infrared-sensitive layer when necessary, and then re-forming the infrared-sensitive layer.

[0002]

2. Description of the Related Art Ordinary flexographic printing plates are disclosed in
As described in JP-A No. 8744 and JP-A-5-134410, it is generally manufactured by using a photosensitive elastomer composition, exposing it to an image through a negative film, and washing out an unexposed portion. It is a target.
The obtained printing plate is attached to the cylinder of the printing press and used for printing.However, it takes a long time to determine the position with high accuracy and paste it, and this operation is simplified, and if possible, omitted It is desired to do.

[0003] When printing a continuous and continuous pattern, there is a problem in the processing of the joint portion of the plate,
After winding a plate-shaped photosensitive resin around a sleeve, etc., a similar liquid resin or a photosensitive elastomer composition dissolved in a solvent is used as an adhesive at the joint, and the swelling generated at the joint is scraped off, and the like. A way to state has been done. However, such an operation requires skill and a long time, and it is difficult to completely eliminate the seam. Therefore, a method for easily obtaining a completely seamless plate has been desired.

[0004] As a method of producing a sleeve-like plate having no seams, a plate-shaped photosensitive resin is wound around a sleeve, and then heated to a temperature higher than the softening temperature of the photosensitive resin to eliminate the seams. There has been taken a method of obtaining a highly accurate seamless resin layer by polishing the surface of the photosensitive resin layer. However, this method has made it possible to obtain a seamless sleeve-shaped photosensitive resin layer without any seams. However, when a negative film is brought into close contact with a plate and exposed to form an image, the end of the negative film is exposed. Are overlapped, and that portion of the resulting printing plate becomes a stepped pattern, so that a seamless printing plate could not be obtained.

On the other hand, recently, Japanese Patent Application Laid-Open No.
No. 30, JP-A No. 9-166875, etc., an infrared-sensitive layer capable of being cut off by an infrared laser and having a property of shielding non-infrared light is provided on the surface of the photosensitive resin, and drawing with the infrared laser is performed. To form a mask, then image exposure through this mask,
Printing plates have been produced by development and drying. Then, using that technology, an infrared-sensitive layer was provided on the seamless photosensitive resin layer, a mask was formed with an infrared laser, and image exposure was performed through this.
Development of a seamless printing plate by development and drying has also been attempted. At that time, in order to provide an infrared-sensitive layer capable of being cut off by an infrared laser and having a non-infrared shielding property on the photosensitive resin layer, a method of applying a solution containing a component constituting the infrared-sensitive layer has been adopted.

When an infrared-sensitive layer is applied to the surface of a photosensitive resin, if foreign matter such as dust adheres to the surface of the photosensitive resin, the infrared-sensitive layer is repelled or, conversely, becomes too thick. Therefore, the application of the infrared-sensitive layer to the surface of the photosensitive resin must be performed in a sufficiently clean environment.However, it is still possible to eliminate the attachment of foreign substances such as dust. It may be difficult, and the infrared sensitive layer may need to be removed and reformed. In addition to this, remove the infrared-sensitive layer once formed on the surface of the photosensitive resin, such as when the infrared-sensitive layer is damaged while handling the sleeve on which the infrared-sensitive layer has been applied. May be required to reproduce the photosensitive resin plate by re-forming.

In response to this requirement, when the binder polymer of the infrared-sensitive layer is a thermosetting elastomer or the like,
It is impossible to peel off the infrared-sensitive layer from the photosensitive resin. When the binder polymer is polyamide or the like, it is possible to peel off the infrared-sensitive layer using an adhesive tape or the like, but since it is a manual operation,
It takes a great deal of time and effort to completely remove the infrared-sensitive layer from the entire surface of the photosensitive resin, and may damage the surface of the photosensitive resin or cause new debris to adhere. There is. Furthermore, if the image needs to be removed after drawing an image on the infrared-sensitive layer, it is practically impossible to separate and remove independent characters, objects, shadows, etc. without damaging the photosensitive resin Had the problem that

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a method for regenerating a photosensitive resin plate by removing the infrared-sensitive layer, which solves the above-mentioned problems of the prior art. It is an object of the present invention to provide a method for removing an infrared-sensitive layer without any need for manual labor and without damaging or scratching the photosensitive resin layer.

[0009]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventor removed the infrared-sensitive layer from the photosensitive resin having the infrared-sensitive layer formed on the surface by drawing the entire surface with an infrared laser. The inventors have found that the problem can be solved, and have completed the present invention. Hereinafter, the present invention will be described in detail. The infrared-sensitive layer that provides the non-infrared shielding layer that can be ablated with an infrared laser in the present invention is one that is abratable by infrared radiation and substantially opaque to radiation active on the photosensitive resin. The infrared-sensitive layer comprises at least one binder polymer, at least one infrared-absorbing substance, and if necessary, a non-infrared shielding substance, and the infrared absorbing substance may also serve as the non-infrared shielding substance.

An example of the binder polymer for the infrared-sensitive layer used in the present invention is described in JP-A-8-305030.
No. 6,098,098, polyamide, polyvinyl alcohol, amphoteric interpolymer, cellulosic polymer,
Examples thereof include ethylene-vinyl acetate copolymer, polybutyral, and cyclic rubber, and styrene-butadiene copolymer and styrene-isoprene copolymer disclosed in JP-A-9-166875. These binder polymers are blended in a ratio of 40 to 90% by weight based on the total weight of the infrared-sensitive layer.

As the infrared absorbing material of the infrared sensitive layer used in the present invention, a simple substance or a compound having a strong absorption in the range of 750 to 2000 nm is usually used.
Examples of such pigments include inorganic pigments such as carbon black, graphite, copper chromite, and chromium oxide, and pigments such as polyphthalocyanine compounds, cyanine pigments, croconium pigments, and metal thiolate pigments. These infrared absorbing substances are added in a range that provides sensitivity that can be cut off by the infrared laser beam used.
Generally, it is added in the range of 20 to 80% by weight as an infrared absorbing substance based on the total weight of the infrared sensitive layer.

As the non-infrared shielding material, a material that reflects or absorbs ultraviolet light can be used. For example, ultraviolet absorbers, carbon black, graphite and the like are good examples, and the amount of addition is set so as to achieve a desired optical density. Generally, it is added so as to have an optical density of 2.0 or more, preferably 3.0 or more. The infrared absorbing material and the non-infrared shielding material may be the same.

The infrared-sensitive layer comprises a binder polymer,
An infrared-sensitive coating liquid is prepared by uniformly dissolving or dispersing an infrared-absorbing substance and, if necessary, a non-infrared-shielding substance in a solvent or water, and applying the liquid to form an infrared-sensitive coating liquid. Infrared-sensitive coating liquids are prepared by adding an appropriate solvent directly to a binder polymer, an infrared-absorbing substance, and a non-infrared-shielding substance, forcing stirring using a stirring blade, dispersion using a ball mill, stirring using ultrasonic waves, or a combination thereof. It is prepared by a method, or a method in which a binder polymer, an infrared absorbing substance, and a non-infrared shielding substance are preliminarily kneaded using an extruder or a kneader and then dissolved in a solvent.

In order to improve the dispersibility of an infrared absorbing substance or a non-infrared shielding substance in a solution, a dispersing agent such as a high molecular weight nonionic surfactant or a phosphoric acid ester of polyoxyethylene alkyl ether is used in the infrared-sensitive coating liquid. Can be added. Infrared-sensitive coating liquids include silicones, long-chain alcohols, and aliphatic esters in order to suppress the generation of air bubbles when transferring the infrared-sensitive coating liquid from a container, and to eliminate the generated air bubbles in a short time. And antifoaming agents such as metal soaps. Infrared-sensitive coating liquids include perfluoroalkyl compounds and sulfonate-type anionic surfactants for the purpose of improving the coatability and leveling of the coating liquid on the surface of the coating, such as photosensitive resin surfaces and polyester films. Surfactants can be added.

As a method for forming an infrared-sensitive layer on the surface of the photosensitive resin, an infrared-sensitive coating solution is directly applied to the surface of the photosensitive resin by a ring coater, a spray coater, or the like, or a polyester, polypropylene, or the like. After being applied to the film of the, it is performed by laminating and transferring to the surface of the photosensitive resin, if the photosensitive resin layer is previously processed into a sleeve shape,
It is effective to apply directly to the surface of the photosensitive resin layer.
The thickness of the infrared-sensitive layer should be determined in consideration of the sensitivity of ablation by an infrared laser and the shielding effect of non-infrared rays, but is usually 0.1 to 20 g / m ² , preferably 1 to ²⁰ g / m ² .
It is set in the range of 5 g / m ² .

An infrared laser having a wavelength of 750 to 2000 nm can be used as an infrared laser used to form a mask by imagewise cutting off the infrared-sensitive layer on the photosensitive resin. As this type of infrared laser, a 750-880 nm semiconductor laser or a 1060 nm Nd-YAG laser is generally used. The laser generation unit is controlled by a computer together with the drive system unit. By selectively cutting off the infrared-sensitive layer on the photosensitive resin layer, the digitized image information can be converted into a photosensitive composition for flexographic printing. It is given to the body.

In the method of the present invention for regenerating a photosensitive resin plate by removing the infrared-sensitive layer, the above-mentioned infrared laser can be used as it is. A solid pattern is prepared as an entire image pattern for removing the infrared-sensitive layer, and the photosensitive resin having the infrared-sensitive layer is set in an infrared laser drawing apparatus and laser-drawn. The photosensitive resin from which the infrared-sensitive layer has been removed is
The infrared-sensitive layer can be applied again by the method described above and used. The photosensitive resin composition to which the infrared-sensitive coating solution is applied in the present invention is generally used as a support layer, such as a polyester film or the like, having a thickness of 75 to 300 μm and a sleeve for flexographic printing. A material obtained by laminating a photosensitive resin on a nickel sleeve, a plastic sleeve, a glass fiber sleeve, or the like can be used.

If necessary, a cushion layer such as urethane foam may be provided below the support layer or between the support layer and the photosensitive resin layer. A layer of film may be provided on the sleeve, in which case the printed sleeve-like flexographic printing element can be peeled off with the film, which is convenient for recycling the sleeve. An adhesive layer may be provided between the support layer, the photosensitive resin layer, the cushion layer, and the like, if necessary. As the photosensitive resin, those known for flexographic printing plates can be used. Generally, the photosensitive resin is mainly composed of a binder polymer, at least one ethylenically unsaturated monomer, and a photoinitiator. Furthermore, depending on the characteristics required for the photosensitive resin layer, a sensitizer, a thermal polymerization inhibitor, a plasticizer,
Additives such as colorants can be included.

A typical example of the binder polymer used in the photosensitive resin layer is a thermoplastic elastomer obtained by polymerizing a monovinyl-substituted aromatic hydrocarbon monomer and a conjugated diene monomer. Examples of the monovinyl-substituted aromatic hydrocarbon monomer include: Styrene, α-methylstyrene, p
-Methylstyrene, p-methoxystyrene, etc., and conjugated diene monomers such as butadiene and isoprene are used. A typical example is styrene-butadiene-
Styrene block copolymer, styrene-isoprene-
Styrene block copolymers and the like can be mentioned.

The at least one ethylenically unsaturated monomer is compatible with the binder polymer,
Examples are alcohols such as t-butyl alcohol and lauryl alcohol, acrylic acid, esters of methacrylic acid and lauryl maleimide, cyclohexyl maleimide,
Maleimide derivatives such as benzylmaleimide, or esters of fumaric acid with alcohols such as dioctyl fumarate, and polyvalents such as hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, and trimethylolpropane tri (meth) acrylate Esters of alcohol with acrylic acid and methacrylic acid can be mentioned.

As a photoinitiator, aromatic ketones such as benzophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether,
It can be selected from known photopolymerization initiators such as benzoin ethers such as α-methylol benzoin methyl ether, α-methoxy benzoin methyl ether, and 2,2-diethoxyphenyl acetophenone, and can be used in combination.

The photosensitive resin layer can be prepared by various methods. For example, if the composition is as described above, the raw materials to be blended are dissolved in a suitable solvent, for example, a solvent such as chloroform, tetrachloroethylene, methyl ethyl ketone, and toluene, mixed and cast into a mold to remove the solvent. It can be evaporated to form a plate as it is. Further, the mixture can be kneaded with a kneader or a roll mill without using a solvent, and can be formed into a plate having a desired thickness by an extruder, an injection molding machine, a press, or the like.

The photosensitive resin layer may be provided on the sleeve by winding a photosensitive resin sheet having a support film around the sleeve, if necessary, and heating the photosensitive resin sheet above the softening point of the photosensitive resin. It is common practice to fuse the seams and then grind them with a grinder to completely eliminate the seams and increase the precision of the photosensitive resin sleeve. After image drawing by the laser is completed, the ultraviolet light source used for photo-curing the photosensitive resin layer of the photosensitive composition for flexographic printing plates includes a high-pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, a xenon lamp, and sunlight. Etc. A desired relief image can be obtained by exposing the image surface with ultraviolet rays.

After the photosensitive resin layer is irradiated with ultraviolet rays to form an image, the photosensitive resin layer is dissolved as a developing solvent used to wash out the unexposed portions of the infrared-sensitive layer and the photosensitive resin layer. Any one having properties can be used, for example, esters such as heptyl acetate and 3-methoxybutyl acetate, petroleum fractions, hydrocarbons such as limonene and decalin, and chlorinated solvents such as tetrachloroethylene. Are used. It is also possible to use a mixture of these solvents with alcohols such as propanol, butanol and pentanol. The washing of the infrared-sensitive layer and the unexposed area is performed by spraying from a nozzle or by brushing with a brush. The obtained printing plate is rinse-washed, dried and post-exposed to finish.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below by way of examples.

EXAMPLE 1 An adhesive Megam 11658 (trade name, manufactured by Kemetal Co., Ltd.) was uniformly spray-coated on the outer surface of a nickel sleeve having an outer circumference of 461.15 mm and a length of 1250 mm at a wet coating amount of 120 g / m ^2. And dried at 60 ° C. for 15 minutes.
This was covered with TGI stockings (trade name, manufactured by Anderson and Vlieland) while stretching so that the fibers did not overlap.

AFP / AFP for flexographic printing
HD-11 (trade name, manufactured by Asahi Kasei Corporation, plate thickness 3.18 m)
m, a short side of size 762 mm × 1016 mm) was cut to have a size of 465.15 mm × 1016 mm.
After the film on the opposite side of the sheet with the slip layer was peeled off, the above-mentioned sleeve was wound around the above-mentioned sleeve with the side from which the film had been removed facing down to 465.15 mm in the circumferential direction without loosening. However, the length of the sheet was slightly shorter than the circumference of the sleeve. After the gap was connected by pulling with an adhesive tape, the area from 5 cm at both ends of the photosensitive resin sheet to the outside of the sleeve was covered with the adhesive tape without any gap.

The photosensitive resin sheet and the sleeve are brought into close contact with each other by evacuating the space between the adhesive tape covering the both ends of the sleeve and the sleeve, and the PET film (cover sheet) on the surface of the photosensitive resin sheet is photosensitive. After cutting along the circumference with a cutter knife just inside the adhesive tape wound around both ends of the resin sheet, the cut inner PET film and the slip layer were peeled off and removed. When the entire sleeve was heated at 130 ° C. for 20 minutes while the space between the adhesive tape and the sleeve at both ends of the photosensitive resin sheet was evacuated, the joint of the photosensitive resin sheet became invisible.

The seamless photosensitive resin sleeve thus obtained is applied to a grinding machine SA6 / 2U.
× 200 (Schleif Maschinenwerk GmbH (Germany)
The photosensitive resin was polished until the outer periphery of the photosensitive resin became 480 mm, whereby a completely seamless sleeve-shaped photosensitive resin was obtained. 60 parts by weight of tufprene 315 (trade name, manufactured by Asahi Kasei Kogyo Co., Ltd., styrene-butadiene block copolymer having a styrene content of 22% by weight), and a particle diameter of 30 n
color black # 30 which is carbon black
A mixture obtained by kneading 40 parts by weight (trade name, manufactured by Mitsubishi Chemical Corporation) with a kneader was dissolved and dispersed in 3-methoxybutyl acetate to prepare a uniform liquid having a solid content of 5% by weight. This was filtered through 300 mesh SUS, and then filtered through a cartridge filter SL-010 (trade name, manufactured by Loki Techno Co., Ltd.) having a filtration accuracy of 1 μ to obtain an infrared-sensitive coating liquid.

As a method for applying an infrared-sensitive coating liquid on the above-mentioned seamless photosensitive resin having a seamless shape, there are the following methods.
Using a vertical ring coater (manufactured by Takagi Sculpture Co., Ltd.), soft chloroprene (thickness: 1 mm, hardness: 45 degrees) was used as a cage rubber. Set the seamless sleeve-shaped photosensitive resin and infrared-sensitive coating liquid in a ring coater,
The coating of the infrared-sensitive coating liquid was performed by lowering the coater portion containing the coating liquid at a speed of 400 mm / min. The sleeve was allowed to stand at room temperature for 30 minutes to form an infrared-sensitive layer on the photosensitive resin. Two sleeve-shaped components were prepared. One of them is (A) and the other is (B).

When the sleeve-shaped structure (A) was set on an infrared laser setter and a solid pattern was drawn on the entire surface, the infrared-sensitive layer was formed without adhering dust or scratching the surface of the photosensitive resin. It could be completely removed. The sleeve and the infrared-sensitive coating liquid were set on a ring coater, and the coater containing the coating liquid was lowered at a speed of 400 mm / min to apply the infrared-sensitive coating liquid. Remove this sleeve at room temperature for 30
After standing for a minute, an infrared-sensitive layer, which was the same as the first coating, could be formed on the photosensitive resin.

The sleeve (A) from which the infrared-sensitive layer has been removed and re-coated as described above and the sleeve (B) from which the infrared-sensitive layer has not been removed are set on an infrared laser setter, and an image pattern is formed. After drawing,
In both cases, a photomask that faithfully reproduced image data could be formed. When the images drawn on these infrared-sensitive layers were analyzed, no difference was seen in the drawing reproducibility between the two as shown in Table 1.

The entire surface of the sleeve-shaped photosensitive resin was coated with an ultraviolet fluorescent lamp of 12 mw / cm ² at 4000 mj / cm ^2.
cm ² after exposure, Solvesso 150 (trade name,
The infrared-sensitive layer was washed off with a brush and a non-exposed part of the photosensitive resin layer was washed out with a mixed solvent of Exxon Chemical Company, aromatic hydrocarbon) / benzyl alcohol = 4: 1 (volume) at 60 ° C. After drying for 1 hour, a flexographic printing plate having no seams was obtained in both cases. When the images formed on these plate surfaces were analyzed, no difference was observed in the plate reproducibility of both plates as shown in Table 1.

[0033]

[Table 1]

Comparative Example 1 Macromelt 6900 (trade name, manufactured by Henkel Co., polyamide) 65 parts by weight and 35 parts by weight of a general-purpose color black # 30 (trade name, manufactured by Mitsubishi Chemical Corporation) which is a carbon black having a particle diameter of 30 nm were kneaded. Was dissolved and dispersed in toluene / 1-propanol = 1: 1 (weight ratio) to prepare a uniform liquid having a solid content of 8% by weight. This is 30
After filtration through 0 mesh SUS, the mixture was filtered through a cartridge filter SL-010 (trade name, manufactured by Loki Techno Co., Ltd.) having a filtration accuracy of 1 μ to obtain an infrared-sensitive coating liquid.

A seamless sleeve-shaped photosensitive resin prepared in the same manner as in Example 1 and the infrared-sensitive coating solution of Comparative Example 1 were set in a ring coater, and the coating solution containing the coating solution at a speed of 400 mm / min. The coating of the infrared-sensitive coating liquid was performed by lowering the part. By leaving this sleeve at room temperature for 10 minutes, an infrared-sensitive layer could be formed on the photosensitive resin.

When an attempt was made to peel and remove the infrared-sensitive layer from the sleeve-like structure using an adhesive tape, dust adhered to the surface of the photosensitive resin during the removal operation, and a trace of the adhesive tape was observed. It has remained as a dent on the surface. The infrared-sensitive coating solution of Comparative Example 1 was re-coated on the sleeve-like structure in the same manner as in Example 1, and an image pattern was laser-drawn on the infrared-sensitive layer in the same manner as in Example 1. When the sensitive layer was washed off and the unexposed portion of the photosensitive resin layer was washed out and dried, traces of dust and adhesive tape were left on the plate as dents, and a good printing plate could be obtained. could not.

[0037]

According to the present invention, there is provided a method for producing a flexographic printing plate corresponding to a plate making process for directly drawing an image which has become digital information using an infrared laser without using a negative film. In the process of forming the infrared-sensitive layer on the surface, the formation of the infrared-sensitive layer may be failed due to the attachment of foreign matter to the photosensitive resin surface, or the formed infrared-sensitive layer may be damaged. When it is necessary to repair the infrared sensitive layer, the infrared sensitive layer is removed without removing any kind of binder polymer of the infrared sensitive layer. This has the effect that the conductive resin plate can be regenerated.

Claims (1)

[Claims] 1. A method of regenerating a photosensitive resin plate by removing an infrared-sensitive layer from an entire surface of a photosensitive resin having an infrared-sensitive layer formed thereon using an infrared laser, and then re-forming the infrared-sensitive layer.