US-12619155-B2 - Method for producing printing plate and printing method

US12619155B2US 12619155 B2US12619155 B2US 12619155B2US-12619155-B2

Abstract

A method for producing a printing plate, containing: an exposure step of forming a relief by the exposure of a photosensitive resin composition; and a developing step of performing development by attaching or adsorbing the photosensitive resin composition of an unexposed portion in the exposure step to a development medium, wherein a storage elastic modulus of the photosensitive resin composition of the unexposed portion at a development temperature of the developing step is 100 Pa or more and 4000 Pa or less, and the development medium is a wiper having an elastic recovery rate of 30% or more and 99% or less.

Inventors

Yuka Yoshida
Takumi Ishii

Assignees

ASAHI KASEI KABUSHIKI KAISHA

Dates

Publication Date: 20260505
Application Date: 20220909
Priority Date: 20211006

Claims (11)

1 . A method for producing a printing plate, comprising: molding a photosensitive resin composition that is liquid at room temperature to form a molded photosensitive resin composition; exposure by forming a relief by the exposure of the molded photosensitive resin composition; and developing by performing development by attaching or adsorbing the photosensitive resin composition of an unexposed portion in the exposure to a development medium, wherein a storage elastic modulus of the photosensitive resin composition of the unexposed portion at a development temperature of the developing is 100 Pa or more and 350 Pa or less, and the development medium is a wiper having an elastic recovery rate of 40% or more and 99% or less.
2 . The method for producing a printing plate according to claim 1 , wherein the storage elastic modulus of the photosensitive resin composition of the unexposed portion at the development temperature is 100 Pa or more and 250 Pa or less.
3 . The method for producing a printing plate according to claim 1 , wherein a loss elastic modulus of the photosensitive resin composition of the unexposed portion at the development temperature is 90 Pa or more and 500 Pa or less.
4 . The method for producing a printing plate according to claim 1 , wherein the elastic recovery rate of the wiper is 60% or more and 99% or less.
5 . The method for producing a printing plate according to claim 1 , wherein a relief depth of the printing plate is set to 0.1 mm or larger and 10.0 mm or smaller.
6 . The method for producing a printing plate according to claim 1 , wherein the wiper is a nonwoven fabric.
7 . The method for producing a printing plate according to claim 1 , further comprising: recovering the photosensitive resin composition of the unexposed portion attached or adsorbed to the development medium as a photosensitive resin composition for the production of a new printing plate.
8 . The method for producing a printing plate according to claim 1 , wherein the photosensitive resin composition of the unexposed portion attached or adsorbed to the development medium is recovered and used as a photosensitive resin composition for the production of a new printing plate.
9 . A printing method comprising: producing a printing plate by the method for producing a printing plate according to claim 1 ; and printing by performing printing using the produced printing plate.
10 . The method for producing a printing plate according to claim 1 , wherein the photosensitive resin composition comprises an ethylenically unsaturated compound, the ethylenically unsaturated compound comprises an ester compound with a polyhydric alcohol, and the ester compound with a polyhydric alcohol is at least one selected from the group consisting of an alkylene glycol, a polyoxyalkylene glycol, a polyalkylene glycol, and trimethylolpropane.
11 . The method for producing a printing plate according to claim 10 , wherein the ester compound with a polyhydric alcohol is the polyoxyalkylene glycol and/or the polyalkylene glycol.

Description

TECHNICAL FIELD The present invention relates to a method for producing a printing plate and a printing method. BACKGROUND ART In recent years, flexographic printing has been widely used as a method for printing soft package materials such as paper or films. A plate material for letterpress printing typified by flexographic printing includes, for example, a photosensitive resin plate. A method for producing a flexographic printing plate from such a photosensitive resin plate includes, for example, the following method. First, the whole surface of a photosensitive resin composition layer is subjected to ultraviolet exposure (called back exposure) through a support to establish a uniform photocured layer. Next, relief exposure is performed from the back side, i.e., the uncured surface side of the photosensitive resin composition layer which is the side opposite to the ultraviolet exposed surface to obtain an original flexographic printing plate. Examples of a method for the relief exposure include a method of performing ultraviolet exposure via a transparent image carrier, such as a negative film, which permits selective transmission of an ultraviolet ray, and a method of performing ultraviolet exposure via a thin layer with an ultraviolet transmitting portion formed by infrared laser ablation based on an image as digital information. The photosensitive resin composition of the unexposed portion of the original flexographic printing plate is removed by washing with a developing solution, for example, so that a relief image is formed to obtain a flexographic printing plate. Meanwhile, a developing step in a dry process which does not use a developing solution has been studied with growing environmental consciousness in recent years. Among others, a heat development scheme, which performs development by heating an original flexographic printing plate after relief exposure to melt an unexposed portion, and removing the melted unexposed portion with a development medium such as a nonwoven fabric, permits development without the use of a solvent and has received attention. A development method that exploits a heat development scheme has been proposed as the above-described developing step in a dry process which does not use a developing solution (see, for example, Patent Document 1). This development method has the advantage that, unlike conventional development methods using a developing solution, neither organic solvent wastes nor contaminated wastewater by-products are generated. This method also has the advantage that a drying treatment for a long time is not required after the development treatment. On the other hand, problems of the heat development scheme compared with conventional development methods using a developing solution are poor developability and residues that tend to remain, because an uncured resin is not dissolved or dispersed in a solvent. Hence, the heat development scheme requires pressing an original flexographic printing plate hard or a plurality of times against a development medium such as a nonwoven fabric in order to enhance developability, and during this course, a plate thickness tends to be decreased. Furthermore, as the original flexographic printing plate has a larger size, the development medium is more difficult to press at a uniform pressure against the whole original flexographic printing plate and the thickness uniformity of a finally obtained flexographic printing plate is more easily impaired. This leads to a problem of easy occurrence of adverse effects such as deterioration in image uniformity at the time of printing. Particularly, the maintenance of thickness uniformity is a technical challenge to large-size flexographic printing plates which are increasingly demanded in recent years. In light of the problems of the heat development scheme regarding image uniformity at the time of printing as described above, a technique of improving image uniformity at the time of printing using a flexographic printing plate by controlling the surface roughness of an original flexographic printing plate at the time of heat development has been proposed (see, for example, Patent Document 2). CITATION LIST Patent Document Patent Document 1: Japanese Patent No. 3117749Patent Document 2: Japanese Patent No. 5827746 SUMMARY OF INVENTION Technical Problem Although the technique proposed in Patent Document 2 controls the surface roughness of a flexographic printing plate, its problem is that the technique is still susceptible to improvement in the thickness uniformity of the flexographic printing plate. In view of the above-described problems of the conventional techniques, an object of the present invention is to provide a method for producing a printing plate excellent in thickness uniformity in the case of using a development treatment in a dry process. Solution to Problem The present inventors have conducted diligent studies in order to solve the problems and have found that the above-desc