JPH0789218B2 - Plate material for flexographic printing and plate making method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flexographic printing plate material and a method for making the same, and more specifically, a flexographic printing plate material through an adhesive layer whose adhesive force is improved by irradiation with actinic rays on a support. After the flexographic printing plate material provided with a photosensitive resin layer and selectively exposing the plate material to actinic rays, the unexposed portion is peeled off to shorten the development processing time and reduce the fatigue of the developer. It concerns less plate making methods.

2. Description of the Related Art In recent years, a flexographic printing plate using a photosensitive resin plate has been developed and put into practical use, but this one is usually provided with a photosensitive resin layer made of a photopolymer having rubber elasticity on a support. It is prepared by exposing actinic rays through a negative film and then dissolving and removing the unexposed portion with a developing solution. Since this method has an advantage that a flexographic printing plate having high printability can be obtained by a relatively simple process, it is now widely used in the flexographic printing field.

However, even when using a flexographic printing plate using a photosensitive resin plate obtained by such a method, when printing on a corrugated substrate having a rough surface such as corrugated board, It is difficult to obtain high-quality printed matter because unevenness in steps and swimming of ink are likely to occur. The reason for this is that the printing pressure has to be slightly higher than usual in order to print evenly on the recesses of the surface of the printing medium that has a rough and wavy surface. It is difficult to apply a uniform printing pressure because the surface of the corrugated cardboards is soft and it is difficult to apply the printing pressure.

In order to solve such a problem, it is necessary to increase the film thickness accuracy of the printing plate and use a plate having higher rubber elasticity, and flexographic printing plates developed based on these ideas are also used. Several have been proposed. For example 1
As one of them, a plate material using a rubber material as a base material of a photosensitive resin layer for flexographic printing has been developed. In this product, after the photosensitive resin layer on the rubber material is selectively exposed to actinic rays, it is subjected to development processing to form a pattern of the photosensitive resin on the rubber material and make a cut in the rubber material. By selectively peeling off the rubber material, a flexographic printing plate having two layers of a rubber material layer and a photosensitive resin layer, having a high rubber elasticity and a relief depth can be provided.

However, although the printing plate thus obtained has a relatively high rubber elasticity, it has a drawback that the film thickness accuracy is unavoidable because a rubber material is used as a base material. ing.

On the other hand, a photosensitive resin plate material for flexographic printing having a film thickness of about 7 mm has been developed. The flexographic printing plate obtained from this product is composed only of a thick film of photosensitive resin and has a higher film thickness accuracy and a higher rubber elasticity than the one using a rubber material as the above-mentioned base material. is doing. However,
The cross-sectional shape of the relief pattern of the flexographic printing plate is desired to have a substantially wide trapezoidal shape. For that purpose, when the plate material is used, a masking step is usually required in the development process, which makes the plate making step complicated. Therefore, there is a problem that skill is required for the work. Further, in the plate material, since the photosensitive resin layer is a thick film, a large amount of resin is dissolved and removed in the development processing, the development processing time becomes unduly long, and the fatigue of the developing solution is fast. There are drawbacks such as.

Then, in order to improve such a defect, for example, a photosensitive layer formed by laminating two layers of the same or different photosensitive resin layers capable of dissolving and removing the unexposed portion with the same developing solution, and a support, After selectively exposing the actinic ray to the flexographic printing plate composed of the above, a contour line is provided along the pattern of the exposed portion to make a notch, and then the unexposed portion of the photosensitive layer upper layer is formed according to the notched portion. A method has been proposed in which only the developing layer is peeled off and then development processing is performed (Japanese Patent Laid-Open No. 61-5 / 1986).
3645 publication).

However, even with this method, a considerable amount of resin must be dissolved and removed, and the problem of rapid fatigue of the developing solution remains. Also, since the photosensitive resin is laminated in two layers,
In addition to the time-consuming manufacturing process, the printing plate obtained has a large plate thickness, which makes it heavy and inconvenient to handle.

Under the circumstances described above, the present invention can shorten the development processing time in the plate making process, reduce the fatigue of the developing solution, and reduce the weight of the printing plate obtained. The purpose of the present invention is to provide a flexographic printing plate material and a plate making method thereof.

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above-mentioned object, and as a result, the adhesive force between the support and the photosensitive resin layer was increased by irradiation with an underlayer and actinic rays. A flexographic printing plate material sequentially provided with an adhesive layer formed of a composition having an improving property is used, and after the plate material is subjected to patterning exposure, only an unexposed portion is subjected to a specific means before development processing. It was found that the object can be achieved by peeling and removing by, and the present invention has been completed based on this finding.

That is, the present invention is a flexographic printing plate material comprising a photosensitive resin layer on a support via an adhesive layer,
A flexographic printing plate characterized in that an underlayer is interposed between the support and the adhesive layer, and the adhesive layer is formed of a composition having a property of improving the adhesive force by irradiation with actinic rays. After selectively exposing the material and the flexographic printing plate material to actinic rays, an edge contour is provided along the pattern of the exposed portion to make a notch, and then only the unexposed portion is removed from the support according to the notched portion. The present invention provides a method for making a plate material for flexographic printing, which is characterized by performing development after peeling.

Hereinafter, the present invention will be described in detail.

Examples of the photosensitive resin composition used in the photosensitive resin layer of the flexographic printing plate material of the present invention include (A) polyisoprene, polybutadiene, isoprene-styrene copolymer, styrene-butadiene block copolymer, and acrylonitrile-butadiene. Copolymers, synthetic rubber-based or natural rubber-based polymer compounds having rubber elasticity such as polyurethane, (B) photopolymerizable monomers such as polyfunctional acrylates,
Examples include (C) a photopolymerization initiator such as a benzoin derivative as a main component.

The thickness of the flexographic printing plate material of the present invention is appropriately selected according to the type of the material to be printed and the type of printing machine used. For example, a plate material having a high rubber elasticity is not required for a material to be printed such as a metal having a hard and flat surface, and a plate material having a high rubber elasticity may be used. For a substrate with a rough surface,
A thick plate material is used because it requires high rubber elasticity. Usually, the total thickness of the photosensitive resin layer is selected in the range of 1.5 to 10 mm, preferably 1.7 to 7 mm.

The support used for the flexographic printing plate material of the present invention is sufficient as long as it has a strength capable of supporting a relief image obtained by exposing and developing the plate material, and can be easily attached to a printing machine to be used. Is. Examples of such a material include flexible sheets such as polyester, nylon, and synthetic rubber, and polyester sheets, steel sheets, and aluminum sheets having high dimensional stability. Particularly, a flexible sheet-like material is preferable because it can be easily attached to a cylinder of a printing machine. The thickness of these supports is not particularly limited, but is practically selected in the range of 0.07 to 0.2 mm.

In the flexographic printing plate material of the present invention, an underlayer and an adhesive layer having a property of increasing the adhesive force by irradiation with actinic rays are sequentially provided between the support and the photosensitive resin layer. This underlayer has a function of improving the adhesiveness as compared with the case where the adhesive layer is directly provided on the support. For example, when polyethylene terephthalate is used for the support,
A composition mainly composed of a saturated polyester resin or hydroxyalkyl methacrylate and polyisocyanate is used, and examples of the composition used in the adhesive layer include polyisoprene, polybutadiene, isoprene-styrene copolymer, and acrylonitrile-butadiene. Initiation of photopolymerization monomers such as copolymers, styrene-butadiene copolymers and other synthetic rubbers, polyesters, acrylic resins and other polymer compounds, and polyfunctional acrylates and other photopolymerizable monomers, and methoxyphenylacetophenone and benzoin, if necessary. The thing which mix | blended the agent is mentioned.

Next, explaining the plate-making method of the present invention, first, to the photosensitive resin layer provided on the support via the underlying layer and the adhesive layer, through the negative film adhered thereon, active Selectively expose light rays. Next, make a cut with a cutter knife etc. from above so as not to scratch the support by providing an edge contour along the pattern of the exposed part, and peel off only the unexposed part according to the cut part. , A pattern including the exposed portion and the edge contour portion is formed. At this time, since the adhesive force of the unexposed portion to the support is weaker than that of the exposed portion, it can be easily peeled off. Finally, this is developed with a developer capable of dissolving and removing the unexposed portion, and after drying, if necessary, post-exposure is performed to prepare a flexographic printing plate.

Examples of the light source of actinic rays used in the plate making method of the present invention include chemical lamps, black lights, carbon arc lamps, high pressure and ultra high pressure mercury lamps, and xenon arc lamps.

Further, in the plate-making method of the present invention, after exposing actinic rays through a negative film, a method of forming an incision by providing an edge contour portion along the pattern of the exposed portion includes a photosensitive resin of a plate material to be used. When both the layer and the support are transparent, while checking the exposure pattern by seeing through from above with the negative film used as the bottom layer,
For example, a method of making a notch or making a notch by exposing the exposed pattern by lightly rinsing the surface with a solvent capable of making a notch or dissolving only the unexposed portion is used. Further, if a photochromic dye is blended with the photosensitive resin composition, only the exposed portion will be discolored and the exposure pattern can be identified, which is convenient for making a notch.

What is important in this cutting is to cut so as to leave a small amount of unexposed portions around the exposure pattern.
This is to obtain a relief shape suitable for printing, and it is usually preferable to leave an unexposed portion within a range of 2 to 10 mm from the edge of the exposure pattern. If it is less than this range, it becomes stable after development processing. It is not preferable because it is difficult to form a preferable relief, and when it is large, the amount of resin to be dissolved and removed increases.

In the method of the present invention, such a cut made is
When there is a fairly wide unexposed portion in the peripheral portion, it is convenient to make a notch in halftone dots, letters, and patterns that are adjacent exposure patterns.

The incision can be performed using an ordinary cutter knife or the like, but care must be taken not to scratch the support or cut the support together. Heating the metal plate,
It is preferable to use a heat cutter that cuts the photosensitive resin by the action of heat because it does not scratch the support.

Further, in the developing treatment, it is preferable to wash and remove the unexposed portion of about 0.5 to 2.5 mm from the surface of the photosensitive resin, instead of completely dissolving and removing the unexposed portion. If all the unexposed portions are removed, the pattern becomes unstable, which is not preferable. Further, the developing time becomes long and the exposed area swells, which is not preferable.

EFFECTS OF THE INVENTION According to the present invention, since a flexographic printing plate material having a photosensitive resin layer with an adhesive layer on the support to improve the adhesive strength by irradiation with an underlayer and actinic rays is used,
Adhesiveness is improved, strong adhesiveness between the adhesive layer and the photosensitive layer is obtained after exposure, peeling does not occur between the support and the photosensitive layer,
An excellent slief shape can be obtained. Further, by peeling and removing only the unexposed portion of the plate material before the developing treatment, the developing treatment time can be shortened, the fatigue of the developing solution can be reduced, and the weight of the obtained printing plate can be reduced. Economical and efficient plate making and printing processing can be performed.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.
The invention is in no way limited by these examples.

Example 1 A polyethylene terephthalate film having a thickness of 0.188 mm,
Saturated polyester resin (Byron 30P, manufactured by Toyobo) 100
Parts by weight triphenylmethane triisocyanate 14 parts by weight dioxane 400 parts by weight methylene chloride 50 parts by weight A composition consisting of 50 μm of dry film thickness is applied, dried at 100 ° C. for 2 minutes, and then at 40 ° C. for 1 hour. Aging treatment was performed to form a base layer.

Next, as an adhesive layer, a composition comprising a styrene-butadiene block copolymer (Tafprene manufactured by Asahi Kasei Kogyo Co., Ltd.) 100 parts by weight trimethylolpropane trimethacrylate 0.5 parts by weight toluene 500 parts by weight methyl ethyl ketone 500 parts by weight was dried. To be 2 μm, and dried at 40 ° C. for 2 minutes to form an adhesive layer.

On the other hand, as the photosensitive resin layer, styrene-butadiene block copolymer (manufactured by Asahi Kasei Kogyo Co., Ltd., Tufrene) 100 parts by weight Liquid polybutadiene having an average molecular weight of 1000 (manufactured by Nippon Soda Co., Ltd.,
Nisso PB-1000) 50 parts by weight trimethylolpropane triacrylate 5 parts by weight methoxyphenylacetophenone 3 parts by weight 2,6-di-tert-butyl-4-hydroxytoluene 0.0
5 parts by weight Oil Blue 603 0.002 parts by weight dissolved in a mixed solvent consisting of 80 parts by weight of toluene and 20 parts by weight of methyl ethyl ketone was pressed into the extruder with a pump for high viscosity, and the solvent was removed under reduced pressure in the extruder. A T type die was used to obtain a photosensitive resin layer having a thickness of 6.8 mm. A 0.1 mm thick polyethylene terephthalate film is laminated as a protective cover on one side of the resin layer, and the polyethylene terephthalate film on which the adhesive layer previously created is formed is attached as a support on the other side to create a plate material. did.

Next, the protective cover of the plate material thus obtained was peeled off, a negative film was brought into close contact with the photosensitive layer, and exposed with a 20 W chemical lamp (FL-20BL, manufactured by Toshiba Corp.) for 8 minutes. When the negative film was peeled off after exposure, a visible image was clearly recognized. About 5 mm from the edge of this visible image was provided with an edge contour portion, and a cut was made using a heat cutter to a cut depth of 6.8 mm. Next, the unexposed portion was peeled off from the support along this cut. At this time, the unexposed portion could be easily peeled off. Thereafter, this plate was developed in trichloroethane for 3 minutes, dried at 60 ° C. for 30 minutes, and then post-exposed with the above lamp for 8 minutes.

In the obtained printing plate, the photosensitive resin layer and the support were firmly adhered. When this plate was placed in a printing machine and printed, a good printed matter was obtained.

Further, the same plate making process was repeated using the same developing solution, but the developing process time did not become long even after processing ² m ² of plate material per 40 l of developing solution.

Example 2 A composition of 0.1 mm thick polyethylene terephthalate film containing 100 parts by weight of hydroxyethyl methacrylate, 10 parts by weight of triphenylmethane triisocyanate, 200 parts by weight of ethyl acetate, 200 parts by weight of toluene, and 20 parts by weight of methylene chloride to give a dry coating of 2 μm. The coating was applied as described above, dried at 100 ° C. for 5 minutes, and then aged at 60 ° C. for 3 days to form a base layer.

Next, as an adhesive layer, a composition consisting of styrene-butadiene block copolymer (Tafprene manufactured by Asahi Kasei Corporation) 100 parts by weight trimethylolpropane triacrylate 30 parts by weight toluene 500 parts by weight methyl ethyl ketone 500 parts by weight was prepared. It was applied so as to have a thickness of 2 μm and dried at 40 ° C. for 2 minutes to form an adhesive layer.

On the other hand, a 0.14 mm thick polyethylene terephthalate film was laminated as a protective cover on one side of a 2.74 mm thick photosensitive resin layer obtained in the same manner as in Example 1, and the previously prepared adhesive layer was formed on the other side. The formed polyethylene terephthalate film was attached as a support to prepare a plate material.

After that, when the plate was made in the same manner as in Example 1, the same result was obtained.

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Claims (2)

[Claims] 1. A flexographic printing plate material comprising a support and a photosensitive resin layer provided on the support via an adhesive layer, wherein a base layer is interposed between the support and the adhesive layer, and the adhesion is performed. A flexographic printing plate material, wherein the agent layer is formed of a composition having a property of improving the adhesive force by irradiation with actinic rays. 2. A flexographic printing plate material according to claim 1, which is selectively exposed with an actinic ray, is provided with an edge contour along the pattern of the exposed portion, and is cut, and then the notch is formed according to the cut portion. A plate-making method of a flexographic printing plate material, which comprises developing only after exposing the exposed portion from the support.