JPH0560855B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to an improvement in a method for manufacturing flexographic printing plates. More specifically, the present invention relates to a method for efficiently producing a high-quality flexographic printing plate having a pattern faithful to a negative film using a negative-working photosensitive resin plate material through a one-step development process. be.

BACKGROUND ART In recent years, flexographic printing plates using photosensitive resin plates have been developed and put into practical use. In this method, a photosensitive resin layer having rubber elasticity is provided on a support, and this is exposed to actinic rays through a negative film.
It is created by a method in which the unexposed areas are dissolved and removed using a developer to form a relief. Such a plate-making method has the advantage that a flexographic printing plate with high printability can be obtained through a relatively simple process, and is currently being widely used in the field of flexographic printing.

However, in this plate-making method for photosensitive resin plates, dots, fine characters, thin lines, etc. that are separated by a sufficient distance from each other are not allowed to pass through the negative film and reach the deep part of the photosensitive resin plate material. Because the amount of transmitted light is small, the support side of the photosensitive resin layer in particular is underexposed, and as a result, dots and fine print are washed out by the developer during the development process.
There was a problem in that the thin lines were deformed into wavy shapes and a pattern faithful to the negative film could not be formed.

This is because the base of the relief is slightly underexposed, so it dissolves during development and the relief becomes unstable. Generally, in order to obtain a stable relief, it is desirable that the cross-sectional shape of the relief be approximately trapezoidal with a wide base.

Conventionally, as a means to solve this problem and obtain a good relief cross-sectional shape, there have been methods such as performing additional exposure by shielding areas other than independent points, fine letters, and thin lines that are underexposed. , protect the independent points, fine letters, and thin line parts by masking them with a polyester film that cannot be dissolved by the developer, and after developing halfway, remove the polyester film and re-open the parts that will become the relief base. A method of developing to the extent that no elution occurs is used.

However, these methods temporarily interrupt the development process, increasing the chances for workers to inhale volatile developer vapor, creating problems in the working environment, or increasing the number of additional exposure conditions. Development processing conditions must be delicately adjusted depending on the shape and size of the desired relief pattern, which may cause problems in terms of workability and are not always fully satisfactory. As the plate-making process is expected to be automated in the future, there is also the problem that removing the masked film during the development process will inevitably become an obstacle to automation.

Problems to be Solved by the Invention The present invention solves the problems of the conventional plate-making method, and uses a negative photosensitive resin material to form a pattern that is faithful to the negative film in a one-step development process in an extremely efficient manner. The purpose of this invention is to provide a method for manufacturing a flexographic printing plate that produces a flexographic printing plate of good quality.

Means for Solving the Problems As a result of intensive research to develop a method for efficiently producing flexographic printing using a one-step development process, the present inventors found that polyester films, etc., conventionally used for masking Instead, by using a resin film that is soluble in a developer as a masking member to protect the exposed area of the photosensitive resin layer and its edge contours during the development process,
The inventors have discovered that the above object can be achieved, and have completed the present invention based on this finding.

That is, in the present invention, a negative photosensitive resin plate material comprising a photosensitive resin layer provided on a support is selectively exposed to actinic rays that have passed through the negative to harden the exposed areas, and then the photosensitive resin plate material is cured. The present invention provides a method for producing a flexographic printing plate, which is characterized in that the exposed portion of the resin layer and its edge contour are protected from a developing solution with a soluble resin film.

The present invention will be explained in detail below.

In the negative photosensitive resin plate material according to the method of the present invention, the photosensitive resin layer provided on the support includes:
For example, polyisoprene, polybutadiene, isoprene-styrene copolymer, acrylonitrile-butadiene copolymer, synthetic rubber-based or natural rubber-based polymeric compounds with rubber elasticity such as polyurethane, and photopolymerizable monomers such as polyfunctional acrylate. A photosensitive resin composition containing a photopolymerization reaction initiator such as a benzoin derivative or the like as a main component is used.
Specific examples of flexographic printing plates provided with such a photosensitive resin layer include Cyrel (product name, manufactured by Dupont), Lunaflex (product name, manufactured by Nippon Paint Co., Ltd.), and Elathlon (product name, manufactured by Tokyo Ohka Kogyo Co., Ltd.). (manufactured by BASF), Niroflex FA (trade name, manufactured by BASF), etc.

The thickness of the photosensitive resin plate material used in the method of the present invention is appropriately selected depending on the type of printing material and the type of printing machine used. For example, printing plates with high rubber elasticity are not required for printing materials with hard and flat surfaces such as paper, metal, and plastic, so the thickness of the printing plates may be relatively thin. A printing plate with high rubber elasticity is required for a soft printing material with a rough surface, such as cardboard, so a thick plate material is used. The total thickness of the photosensitive resin layer is usually selected in the range of 1.5 to 10 mm, preferably 1.7 to 7 mm.

The support used for the photosensitive resin plate material used in the method of the present invention must have enough strength to support the relief image obtained by exposing and developing the plate material, and be easily attached to the printing machine used. There is no particular restriction as long as it can be used. Examples of such materials include flexible sheet materials such as polyester, nylon, and synthetic rubber, as well as polyester plates, steel plates, and aluminum plates with high dimensional stability. A flexible sheet-like material is preferred because it is easy to attach to the cylinder of a printing press and can also serve as a protective cover. There are no particular restrictions on the thickness of these supports, but in practice the thickness is 0.07
Selected within the range of ~0.2mm.

The resin film used as a masking member in the method of the present invention is not particularly limited as long as it can be dissolved in the developer used when developing the photosensitive resin plate material, but it is the same as the photosensitive resin layer. It is preferable to use a material with similar properties to the surface of the photosensitive resin layer because it can be evenly bonded to the surface of the photosensitive resin layer without using an adhesive. For example, as a mask member, a resin film whose base material is the one mentioned above as the photosensitive resin layer can be used. The thickness of the resin film is appropriately selected depending on the maximum relief depth and cross-sectional shape of the flexographic printing plate to be obtained, the dissolution rate of the resin film used, etc., but in practice it is 0.1 to 5 mm.
degree is desirable.

Next, a preferred example of the method of the present invention will be described.
Selectively expose to actinic light. Next, a resin film of a masking member cut out approximately 2 to 10 mm larger than the edge of the pattern in the exposed area is pasted on the corresponding pattern, and then this is removed using a developer that can dissolve and remove the unexposed area and the masking member. Develop and process. At this time, the masked portions are developed after the masking member is dissolved and removed, so the development time is substantially shorter than that of the unmasked portions, and therefore, the masked portions are excessively developed and dotted. The base of the thin line pattern is not eluted. Next, after drying, post-exposure is performed as necessary to create a flexographic printing plate.

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

In addition, in the method of the present invention, as a method of pasting a masking member to the pattern of the exposed area, for example, a method of pasting a masking member cut out in advance according to the negative film to be used in correspondence with the negative film, a method of pasting a masking member that corresponds to the negative film, It is possible to use a method in which a dye is blended into the photosensitive resin layer, only the exposed area is raised, and then the exposed area is cut out while being directly applied with a masking member.

The masking performed in the method of the present invention is advantageous for dots, fine characters, and thin lines, and it is not necessarily necessary to mask large exposure patterns, thick characters, and designs.

Effects of the Invention According to the method of the present invention, the exposed area of the photosensitive resin layer and its edge contour are protected with a resin film soluble in a developer and developed.
A high-quality flexographic printing plate having a pattern that is faithful to the negative film even in terms of dots, fine characters, and fine lines can be produced extremely efficiently in a single development process.

Examples Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Example A photosensitive resin plate material Elaslon M-300 (product) is made by using a polyester film coated with an adhesive as a support, providing a 3 mm thick photosensitive resin layer on the support, and further protecting this layer with a polyester film. A 20W chemical lamp (manufactured by Toshiba Corporation, FL-) was used from the support side.
20BL) for 45 seconds. Next, the polyester film for protection was peeled off, a negative film was adhered onto the photosensitive resin layer, and the negative film was exposed to light for 6 minutes using the lamp.
After exposure, when the negative film was peeled off, the exposed area was decolored and a visible image was clearly recognized.

As a masking member, a 1.0 mm thick photosensitive resin layer excluding the support and protective film of an unexposed flexographic printing plate material Elaslon M-100 (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used. Then, while directly applying it to the visible image, it was cut out about 5 mm larger than the visible image and crimped. This masking member is
Due to the adhesiveness of the masking member itself, it was possible to uniformly adhere the masking member to the surface of the photosensitive resin layer on which the visible image was formed.

After that, it was developed in trichloroethane for 3 minutes and 20 seconds, dried at 60℃ for 20 minutes, and then post-exposed for 8 minutes using the same lamp to form a pattern that was faithful to the dots, fine letters, and lines. A flexo printing plate was obtained.

When the printing plate thus obtained was printed on a printing machine, good printing was obtained.

Claims (1)

[Claims] 1. A negative photosensitive resin plate material comprising a photosensitive resin layer provided on a support is selectively exposed to actinic rays passed through the negative to cure the exposed areas, and then the exposed areas of the photosensitive resin layer are cured. A method for producing a flexographic printing plate, characterized in that the flexographic printing plate and its edge contour are protected from a developer with a soluble resin film.