JP2000098628A - Relief printing plate for applying varnish for offset printing without requiring developing process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a relief printing plate which does not require a developing process by using a photosensitive color coating agent containing a photofading dye and photopolymn. initiator as an essential component to form a relief image. SOLUTION: A PET film and a synthetic rubber material are laminated and plate thickness adjustment and vulcanization are performed at one time. Then, a soln. of a photosensitive color coating agent having photofading property is applied to obtain a laminated body (relief printing plate material). The photosensitive color coating agent is a compsn. containing a photofading dye, a photopolymn. initiator and a polymer matrix. As for the photofading dye, the compd. which fades by exposure to UV rays in a short time and which forms an image of high contrast is preferable. Then, a photographic film is tightly adhered to the relief printing plate and irradiated with UV rays by using an exposure device for photograving. Then, a base material in an unexposed region is peeled off by using a blade to produce a relief printing plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The relief printing plate of the present invention has a printing varnish coated on the surface of a printed material after offset printing by a printing method, and imparts gloss or semi-gloss to the surface of the printed material, that is, polishes or mats. It relates to a relief printing plate for processing. Paper utensils,
Many labels, stickers, book covers, magazine and catalog covers, postcards, posters, etc. are coated with varnish on the surface of process prints, and are used to enhance the added value of the prints, such as cosmetics or improved protection. printing·
It is suitable for the so-called overprint varnish processing field, which is expected to improve work efficiency by in-line varnish coating processing.

[0002]

2. Description of the Related Art Surface varnish coating of printed matter (hereinafter abbreviated as varnishing) is used for imparting gloss or semi-gloss to the surface or for imparting water resistance, weather resistance and the like. Varnishing of the surface of a printed material includes a full-surface processing and a partial processing. Supervised by Yoneho Tabata "U
According to the application and market of VEB curing technology, pp. 224 to 235 (published by CMC, 1989), varnishing on the entire surface includes so-called vinyl drawing, press coating, print lamination, etc. It is described that there is a problem from the viewpoint of the method, and that the coating unit is set in an offset printing machine and the in-line processing is increasingly performed in addition to the off-line processing.

As a more recent tendency, varnishing is performed on only a part of a design, that is, partial varnishing is rapidly spreading. To perform a partial varnishing,
Regardless of the off-line coating or in-line coating, a printing plate having a relief corresponding to the image of the portion to be processed (hereinafter, abbreviated as a relief printing plate) is required. However, a method of manufacturing a relief printing plate has not been established, and a method of performing so-called physical peeling, such as hand-engraving, on a rubber blanket used in an offset printing machine and using it as a printing plate is generally performed. Hand-carved sculpture involves cutting the rubber material along the contour of the object to be processed until it reaches the interface with the support and removing the non-relief part, which requires a long time, skill and costly work Nevertheless, there is a disadvantage that it is difficult to obtain a precise image relief. Therefore, although a physical peeling method is followed, development of a relief printing plate that is precise, saves cost and time, and has a good varnish acceptability and transferability is expected.

[0004] In response to this expectation, the following two methods have been developed. (1) A method of producing a relief printing plate using an ultraviolet curing process, that is, a material for a rubber blanket used for offset printing as a material having good varnish acceptability and transferability, having good dimensional stability and good attachment to a plate cylinder. PE
Photosensitive dye on the laminate formed on T film
A sheet having a printing plate function is manufactured by coating a mixture of diazo resins. Next, UV exposure is performed through a photofabrication method, that is, through a photographic film, developed with a liquid such as an organic solvent or water, and a dye / diazo resin in an unexposed portion is removed by elution to obtain a colored image. Subsequently, a knife is used along the contour of the colored image to reach the interface with the PET film, and the non-exposed portion is removed to obtain a relief printing plate. Alternatively, (2) a cutting plotter is driven by a CAD signal on a non-photosensitive rubber-like sheet formed on a PET film. That is, there is a method of obtaining a relief printing plate by cutting the sheet along a contour with a needle that moves up and down and removing a non-relief portion. Both methods have been put to practical use.

[0005]

A comparison between these two methods, ie, the photofabrication method and the cutting plotter method, shows that (1) in terms of environmental protection, the former requires an elution step, while the latter does not. In addition, in the elution step, since the development waste liquid always comes out, the waste liquid must be treated, which is not preferable from the viewpoint of environmental conservation.
(2) In terms of economy, the former can use a plate-making exposure apparatus already owned by a plate-making company, while the latter requires a large amount of new capital investment. In order to solve these requirements, the appearance of a relief printing plate that can use a conventional plate making apparatus and can omit the development step is desired.

[0006]

A conventional relief printing plate uses a mixture of a water-soluble dye and a diazo resin as an image forming means. In these, the colored coating layer corresponding to the exposed portion is made water-insoluble by a photochemical reaction in a form in which the diazo resin embraces the dye. The colored coating layer in the non-exposed area is developed, that is, eluted and removed using an aqueous solution in many cases, so that the image can be recognized only after being removed. It was hypothesized that if a composition containing a photobleachable dye and a polymer matrix was coated instead of a mixture of dye and diazo resin, the dye in the exposed area would fade, so that the image could be recognized even if the development step was omitted. I was In other words, a relief printing plate that does not require a development step can be achieved by coating a composition mainly composed of a photobleachable dye and a polymer matrix on a sheet made of a material having excellent varnish acceptability and transferability. Was.

The inventors of the present invention have studied a material system which satisfies the technical requirements disclosed in the section of the problem to be solved by the invention. Laminate molding is performed using a pressure press that has been set, and plate thickness adjustment and vulcanization are simultaneously performed. Next, (2) a solution of a photosensitive coloring coating agent having photobleaching property is coated to form a laminate (hereinafter, referred to as “laminate”). (Referred to as a relief printing plate material), and (3) a method for improving printability in varnishing using the printing plate.

In forming an image, a photographic film is brought into close contact with a relief printing plate using a photolithography exposure apparatus, and irradiated with ultraviolet light. Next, the blade is cut along the contour of the colored image with a blade until the interface with the PET film is reached, and the material in the non-exposed area is peeled off to produce a relief printing plate. Both positive and negative photographic films can be used, but the use of positive films makes it easier to strip off the non-exposed areas.

Some of the examination results have already been filed in the application (Japanese Patent Application No.
218492) (hereinafter abbreviated as prior application). The relief printing plate material of the earlier application is (1) a material having a good varnish receptive transfer property and a property close to an offset printing blanket;
(2) a photosensitive coating film containing a photobleachable dye, and (3) a three-layer laminate of a support film, that is, a relief printing plate material. Even after the filing of the application, in order to further enhance the effect of the coating film varnish drawing, as a result of repeatedly examining each of the above three elements (1) and (2), it was possible to greatly improve the results. Reached. The details will be described below.

A rubber-based material is suitable as a material having a good varnish-accepting transferability and a property close to that of an offset printing blanket. As the rubber material, a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer can be used alone or as a blend with another rubber. In the prior application, random copolymers, particularly ethylene-propylene-diene rubber, are preferred from the viewpoint of printability, and the components are ethylene and propylene, and the third component is ethylidene so that ordinary sulfur vulcanization and peroxide crosslinking can be carried out. It is disclosed that those to which a diene such as norbornene or 1,4-hexadiene is added can be used. For vulcanization, it must be heated to at least 150 ° C. On the other hand, since the PET film as the support softens at around 140 ° C., if the laminating operation is not performed carefully, the flatness may be lost.

[0011] Then, as a result of examining a rubber material which does not require a vulcanization step while maintaining a property similar to that of an offset printing blanket while maintaining good varnish acceptance transferability, a thermoplastic elastomer can be used in the same manner as a vulcanized rubber material. And excellent printability. Regarding thermoplastic elastomers, Kohei Komatsu, “Thermoplastic Elastomers”, pp. 9-12 (published by Nikkan Kogyo Shimbun, 199
5) As described, (1) polystyrene: styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene block copolymer, (2) Polyolefin type: simple blend type (s-TPO), implanted TPO (i-TPO)
TPO), dynamic vulcanization type (TPV), (3) polydiolefin type: syndiotactic-1,2-polybutadiene, trans polyisoprene, natural rubber type TPE,
(4) Chlorine: polyvinyl chloride; (5) Engineering plastic: polyurethane, polyester, polyamide, fluorine, etc. can be used. Particularly, a polyurethane elastomer belonging to (4) is suitable. Polyurethane elastomers are general-purpose elastomers, have elastic deformation, have good moldability, are suitable for price, and have good printability and are suitable for practical purposes. The compression temperature is 85-122 ° C
Therefore, there is almost no danger that the flatness is lost during the production of the relief printing plate material. Polyethylene-vinyl acetate (EV), which is a high-pressure copolymer of ion-crosslinking ethylene-vinyl acetate, which belongs to a thermoplastic elastomer but has little elastic deformation and has no clear boundary with these thermoplastic elastomers
A) can also be used.

As the photobleachable dye, a dye capable of fading upon exposure to ultraviolet light for a short time and forming a high-contrast image is preferable. Specifically, although the structure is not clear,
Any dyes that are generally called photosensitive dyes, such as those added to V-cured resins and used to check the polymerization rate, can be used. Considering the workability of removing the non-image area, the color is reddish and bluish, and the absorption spectrum is 450-550 nm and 500-63 nm, respectively.
Compounds that absorb in the wavelength range of 0 nm are suitable. For example, UV Red 101 (λmax 503n
m), UV Blue 18 (λmax 567n
m), UV Blue 236 (λmax 626n
m), UV Blue 784 (λmax 624 nm)
In each case, Mitsui Toatsu Dye Co., Ltd. products can be used. Considering the contrast of the image or the workability of removing the non-image area, a blue color is preferable.

When a known photopolymerization initiator is used in combination,
Even though the exposure time is almost the same, the contrast of the image can be significantly improved. The addition amount is preferably 5 to 50% based on the dye. When the amount exceeds the upper limit of the preferable range, a dark reaction occurs, which may cause so-called fog.
Below the lower limit, little improvement in contrast is observed. Examples of the photopolymerization initiator include benzoin ethyl ether, benzoin isopropyl ae, benzoin dimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, and diethoxyacetophenone. Photo-radical polymerization initiators such as benzoin alkyl ethers, aryl alkyl ketones, oxime ketones, acyl phosphine oxides, aryl alkyl ketones, and other direct-dissociation-type compounds, and various hydrogen abstraction-type compounds typified by such compounds can be used.

For coating, flow coating is suitable. As the coating liquid, a mixed solution of a dye and a polymer solution as a binder is used. The dye can be used in a range of 0.1 to 1.0% (weight) with respect to the binder. As the binder, various polymers can be selected according to the solubility of the photobleachable dye, from a water-soluble polymer such as polyvinyl alcohol to an alcohol-soluble polyamide and an air-drying acrylic resin for a solvent-soluble paint. From the viewpoint of coating workability, the viscosity (20 to 60 seconds / No. 4F.
Solutions of C) are suitable.

It has been found that a very interesting phenomenon can be obtained by coating a polar solvent-soluble polymer such as an alcohol-soluble polyamide, a photobleachable dye, and a solution of a photopolymerization initiator as a binder. . That is, the coating film on the relief surface can be easily removed after the exposure step. Although the reason is not clear, it is assumed that the use of a binder having a strong internal cohesion, such as polyamide, reduces the adhesion to the material. If the coating film remains and the coating film peels off during printing, there is a difference in print reproduction quality before and after the coating film is peeled off. If the coating film is peeled off before printing to expose the material surface, such troubles can be avoided and the printability can be stabilized. The peeling of the coating film may be performed after the exposure and before or after the material in the unexposed portion is peeled and removed by a physical method. Even if the film removal operation is performed before the removal by the physical method, the dye is transferred to the material surface, so that there is no problem in removing the material of the non-exposed portion by the physical method along the outline of the object. One of the effects of the present invention is that the image is transferred with the transfer of the dye to the material surface. In addition, when a naturally soluble acrylic resin for solvent-soluble paint is used as a binder, the adhesion between the coating film and the support is good, and the peeling operation is difficult, but on the other hand, it naturally peels during printing and affects print reproduction quality. Has little effect.

The thickness of the PET film of the support is 350 μm from the viewpoint of mounting on a plate cylinder of a printing press and its printing workability.
m is suitable. Further, in order to improve the physical adhesion between the PET film and the rubber sheet interface, the surface of the PET film is matted. 40 for abrasive
Pumice of about 0 mesh is suitable.

In the production of a relief printing plate material, when a rubber material that needs to be vulcanized is used, a kneaded material of a rubber material in a molten state, a vulcanizing agent, and a PET film are stacked, and the thickness is set in advance. When vulcanization and molding are performed using a pressurized press, a rubber / PET laminated board corresponding to the set thickness is obtained.
A matted film is used on one side of the PET film in order to improve the adhesion to the rubber sheet due to the anchor effect. When a rubber / PET laminate is coated with a dye solution using a curtain coater, a relief printing plate material is obtained. The rubber sheet thickness is preferably from 1.00 to 0.10 mm, but is preferably from 0.85 to 0.40 mm. If the thickness exceeds the upper limit, not only is it difficult to peel off the non-exposed portion, but also the printability as offset printing deteriorates. If the lower limit is exceeded, the varnish film thickness will decrease, and the effect of varnishing will decrease. In the case of a thermoplastic elastomer that does not require a vulcanization step, the melted elastomer to which a crosslinking agent has been added as necessary and the PET film are stacked and molded using a pressure press having a preset thickness to obtain a rubber or elastomer. A PET laminate is obtained. When processed in the same manner as in the case of a vulcanized rubber material, a relief printing plate material is obtained.

As the printing varnish, a UV-curable clear coating or a water-dispersed clear coating can be used.
In addition, an enamel can be used in addition to the clear as needed. The type of the rubber material is appropriately selected depending on the type of the varnish.

[0019]

EXAMPLES The present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Unless otherwise specified, "parts" indicates parts by weight and "%" indicates% by weight. Example 1 Production of Rubber / PET Laminate (A) Ethylene / propylene / diene rubber (trade name J
A rubber material (commercially available) obtained by vulcanizing SREP) and a mat-processed PET film (thickness: 350 μm, using a 400 mesh abrasive) are set in a pressure press adjusted to have a thickness of 1.15 mm. When pressed, the thickness is 1.
A 15 mm (rubber thickness 0.8 mm) rubber / PET laminate is obtained. The molding conditions are a temperature of 140 ° C. and a time of 20 minutes. (B) A commercially available adipate-based polyurethane elastomer (trade name: Pandex T-5010) and a matte-processed PET film (thickness: 350 μm, using a 400-mesh abrasive) are pressurized so as to have a thickness of 1.15 mm. Set in a press and press mold. Molding conditions are 122
° C, time 5 minutes.

Example 2 Coating of Photosensitive Liquid UV Blue 236 (manufactured by Mitsui Toatsu Dye Co., Ltd.) 0.1 was applied on the rubber / PET laminate prepared in Example 1 (A) or 1 (B). Parts, photopolymerization initiator (Irgacure 6
51 Ciba Special Chemical Co., Ltd.) 0.0
3 parts are dissolved in 10 parts of isopropyl alcohol, mixed with 1.0 part of an air-dry type acrylic lacquer, and coated using a curtain coater. The film thickness is 1.0-2.0μ
Adjust the coating speed to m. Viscosity is the viscosity with lacquer solvent (20-60 seconds / No.4FC)
Adjust so that Relief image forming method Relief plate material [Rubber / PET laminate (Example 1 (A)
And (B) coated with the above photosensitive coating]
And a photographic negative corresponding to the portion to be varnished are set in a flexographic plate-making exposure apparatus JE-AO-SH (manufactured by JEOL Ltd.) and exposed to ultraviolet light for 5 minutes under reduced pressure. The dye in the exposed areas fades and produces sharp contrast with the unexposed areas. Using a blade (trade name: NT cutter), the blade is cut along the contour of the colored image until it reaches the interface with the PET film, and the non-exposed portion is removed to obtain a relief printing plate. When mounted on a plate cylinder and printed in the same manner as a normal printing plate, a varnished printed matter is obtained.

EXAMPLE 3 Coating of Photosensitive Liquid UV Blue 236 (manufactured by Mitsui Toatsu Dye Co., Ltd.) 0.1 on the rubber / PET laminate prepared in Example 1 (A) or Example 1 (B). Parts, photopolymerization initiator (Irgacure 6
51 Ciba Special Chemical Co., Ltd.) 0.03
Was dissolved in 10 parts of isopropyl alcohol, and an alcohol-soluble polyamide [Nylon C-80 manufactured by Toray Industries, Inc.]
00] and coat with a curtain coater. The coating film speed is adjusted so that the film thickness becomes 1.0 to 2.0 μm. The viscosity is adjusted to a viscosity (20 to 60 seconds / No. 4FC) with a lacquer solvent. Relief image forming method (1) Relief printing plate material [rubber / PET laminate (Example 1)
(A) and (B), the photosensitive coating described above] and a photographic negative corresponding to the portion to be varnished are set in a flexo plate-making exposure apparatus JE-AO-SH (manufactured by JEOL Ltd.). UV exposure for 5 minutes under reduced pressure. The dye in the exposed areas fades and produces sharp contrast with the unexposed areas. Knife (brand name NT cutter)
Is used along the outline of the colored image to reach the interface with the PET film, the material in the non-exposed area is removed, and then the coating film present on the exposed surface is peeled off to obtain a relief printing plate. (2) A photographic negative corresponding to a portion where the above-described photosensitive coated relief printing plate is varnished is exposed to a flexographic plate-forming exposure apparatus JE-AO-SH (JEOL Ltd.)
And exposed to ultraviolet light under reduced pressure for 5 minutes. The dye in the exposed areas fades and produces sharp contrast with the unexposed areas. When the coating film is peeled off, an image transferred on the material surface due to the transfer of the dye is observed. When a blade (trade name: NT cutter) is cut along the contour of the colored image to reach the interface with the PET film, and the non-exposed portion is peeled off, a relief printing plate is obtained. When mounted on a plate cylinder and printed in the same manner as a normal printing plate, a varnished printed matter is obtained.

[0022]

The present invention relates to a relief printing plate for coating a printing varnish on a surface or a part of a pattern of an offset-printed printed material to impart gloss or semi-gloss to the surface of the printed material. Used to add value to printed materials. This makes it possible to omit the liquid developing step which is indispensable in the conventional relief forming by hand carving or the image forming method by photofabrication which has recently become popular.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/027 502 G03F 7/027 502 7/028 7/028 7/032 502 7/032 502 7/035 7/035 7/34 7/34 7/40 511 7/40 511 F term (reference) 2H025 AA00 AA04 AB03 AB20 AC01 AD07 BH00 CA00 CC13 CC20 DA14 DA19 FA19 FA24 2H096 AA06 AA30 BA20 EA02 GA50 GA60 HA30 2H113 AA02 BA05 BB02 BC00 CA25 FA10 FA40 FA48 2H114 AA04 AA15 AA23 AA30 BA02 DA56 DA73 EA01 EA04 GA01

Claims (11)

[Claims] 1. A material suitable for a polyester film or a blanket for an offset printing machine, and a photosensitive coloring coating agent comprising a photobleachable dye and a photopolymerization initiator as essential components, which are exposed only to the surface of the material and do not require a development step. A method of forming a relief image by exposing a photosensitive colored coating surface of a laminated plate coated with a photographic film through a photographic film, and then removing a material of a non-exposed portion by a physical method. 2. A material suitable for a polyester film or a blanket for an offset printing machine, and a photosensitive coloring coating agent comprising a photobleachable dye and a photopolymerization initiator as essential components, which are only exposed to the surface and do not require a development step. After exposing the photosensitive colored coating surface through a photographic film, the exposed coating film on the surface is removed, and then the unexposed material is physically removed. Through the process of removing with the technique,
A method of forming a relief image free of a coating film. 3. A material suitable for a polyester film or a blanket for an offset printing press, and a photosensitive coloring coating agent comprising a photobleachable dye and a photopolymerization initiator as essential components, which are exposed only to the surface and do not require a development step. After exposing the photosensitive colored coating surface through a photographic film on the laminated plate coated with the above, the material of the non-exposed area is removed by a physical method, and then the exposed coating film present on the exposed surface is peeled off. Through the process of removing the film,
A method of forming a relief image free of a coating film. 4. A material suitable for a polyester film or a blanket for an offset printing machine, and a photosensitive coloring coating agent comprising a photobleachable dye and a photopolymerization initiator as essential components, wherein only a surface of the material is exposed and a development step is unnecessary. The laminate according to claim 1, wherein the laminate is coated. 5. A material suitable for a polyester film or a blanket for offset printing, and a photobleachable dye having a photobleaching property capable of removing the coating film after exposure by exposing only the surface of the material without exposure, and removing the coating film after exposure. 4. The laminate according to claim 2, which is coated with a photosensitive coloring coating agent containing a photopolymerization initiator as an essential component. 6. The photosensitive colored coating composition according to claim 4, wherein the photosensitive colored coating agent is a composition containing a photobleachable dye, a photopolymerization initiator, and a polymer matrix. 7. The composition according to claim 6, wherein the polymer matrix in the photosensitive coloring coating agent is a polar solvent-soluble substance. 8. The laminate according to claim 4, wherein the material suitable for an offset printing press blanket is a polymer comprising an α-olefin and a compound having a polymerizable double bond. 9. A material suitable for an offset printing press blanket is a thermoplastic elastomer.
A laminate according to item 1. 10. The polymer according to claim 9, wherein the thermoplastic elastomer is a polyether-based or polyester-based polyurethane. 11. A varnished offset printed matter using a relief printing plate produced from the laminate according to claim 4.