JPS5939313B2 - Molding method for thermoplastic resin intaglio or letterpress - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding an intaglio or letterpress plate made of thermoplastic resin with good reproducibility.

More specifically, when using a thermoplastic resin sheet to mold a thermoplastic resin matrix intaglio from a printing original letterpress for printing such as metal letterpress, photosensitive resin letterpress, or typesetting, or a thermoplastic resin matrix intaglio. This invention relates to a method for removing air bubbles when molding a printing relief plate using a thermoplastic resin sheet.

Conventionally, when molding a matrix intaglio from a printing original letterpress using a thermoplastic resin sheet as a plate material, or when molding a printing relief from a thermoplastic resin sheet from a matrix intaglio, the original platelet or the matrix A method is adopted in which an intaglio plate and a thermoplastic resin sheet are stacked and preheated, and then, after passing through a pressure press and a pressure press, the original letterpress plate or matrix intaglio plate and the embossed thermoplastic sheet are cooled in the embossed state. ing.

However, in this molding method, the air contained in the uneven parts of the original letterpress or intaglio matrix is sealed at the interface between the original letterpress or intaglio matrix and the resin by the thermoplastic resin sheet that is melted or softened during heat pressing, and the molding pressure is reduced. When the molding pressure is high, the air bubbles are incorporated into the molded intaglio or letterpress, and when the molding pressure is low, they remain on the surface of the intaglio or letterpress. The generated air bubbles reduce mechanical properties such as compressive strength and impact strength. Furthermore, if air remains on the uneven surface of the thermoplastic resin sheet, accurate reproduction of the original letterpress or master intaglio is hindered. These defects are fatal defects in printing master molds or printing relief plates.

The present inventors have degassed during heat pressing when molding a thermoplastic resin matrix intaglio or a duplicate letterpress from this matrix intaglio, and created a matrix that accurately reproduces the characters, patterns, etc. of the original letterpress or matrix intaglio. As a result of extensive research into the method of obtaining molded intaglios or duplicate letterpresses, it is possible to obtain intaglios or letterpresses with extremely good reproducibility without bubbles or residual air on the surface by using a molding method that completely releases the pressure once during heat pressing. This discovery led to the present invention.

The present invention uses a thermoplastic resin sheet as a plate material, and is a method for molding a thermoplastic resin intaglio plate from a letterpress original plate, or a thermoplastic resin printing letterpress plate from a thermoplastic resin matrix intaglio plate by hot press. This is a method for molding an intaglio or letterpress plate made of thermoplastic resin, characterized by removing the pressure for one day during pressurization during molding, and then applying pressure again.

To explain the present invention in detail, a letterpress printing plate or a thermoplastic resin is placed on the lower mold of a press molding device, each of which has a heating heater and a temperature control device, and one of which has upper and lower molds that can move up and down. Place the mother mold intaglio and the thermoplastic resin sheet one on top of the other.

Activate the mold on the moving side and press the stack of the original letterpress or intaglio matrix and the thermoplastic resin sheet until there is no gap between the upper and lower molds. Stop the scissor press until the thermoplastic resin sheet softens and melts. Preheat. When the temperature of the thermoplastic resin sheet has risen to a temperature that allows embossing, the mold on the moving side is moved at a slow speed, and the molten or softened thermoplastic resin sheet is pushed into the original letterpress or intaglio matrix to perform embossing. During the embossing process, the mold is opened and the applied pressure is released. By removing the pressure during pressurized embossing, the air compressed and sealed by the pressure applied to the original letterpress or intaglio matrix and the thermoplastic resin sheet quickly escapes through the interface between the two materials. After pressure is removed, base pressure is applied to remove the air remaining in the concave and convex portions where embossing is to be completed, and the sufficiently embossed thermoplastic resin sheet is cooled together with the letterpress original or intaglio matrix to complete the forming. In this way, intaglios and letterpresses can be obtained that are free of residual air, bubbles, reproducibility, and mechanical properties.

The original letterpress plate used in the present invention is a letterpress plate used for general printing such as metal etching plate, photosensitive resin letterpress plate, typesetting, etc., and the matrix intaglio plate is a thermoplastic resin intaglio plate molded from the original letterpress plate.

The thermoplastic resin sheet used in the present invention includes polyolefin, polypinylidene chloride monovinyl chloride polymer, polyacrylate, polymethacrylate, ABS resin, polystyrene, polyamide, polycarbonate, polyhydroxyether, polyarylene polyether, It is a resin sheet containing polyacetal, the above alone or a copolymer, or a mixed composition.

The present invention will be explained below with reference to Examples.

Example 1 A metal letterpress plate made of zinc with an area of 580u x 424u and a thickness of 1.0u and an area of 580711J1 x 440rf1J! L. A 2.0u thick polycarbonate sheet was placed on top of the lower mold held at 150°C, and the upper mold was heated to 340°C.
Heat to.

An iron plate with a thickness of 1.0 U with good mold releasability is placed between the polycarbonate sheet and the upper mold.For molding, the metal letterpress and polycarbonate are stacked and preheated for 60 seconds, and after completion of the molding, the pressure is increased. Two seconds after the pressurization started, when the pressurization reached 80 tons, the mold was lowered to completely release the pressure. 2
After 0 seconds, pressurization was started again, and the pressure was increased to 120 tons in 3 seconds, and then 120 tons was maintained for 6 seconds.

Claims (1)

[Claims] 1. In a method of molding a thermoplastic resin matrix intaglio from a letterpress original plate, or a thermoplastic resin printing relief plate from a thermoplastic resin matrix intaglio by hot pressing, using a thermoplastic resin sheet as a plate material. A method for molding an intaglio or letterpress plate made of thermoplastic resin, which is characterized in that during press molding, the pressure is temporarily released during pressurization, and then the pressure is applied again.