JP2011214947A - Method of determining mechanical engraving aptitude and separation aptitude in copper-plated coating of printing plate for gravure printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of determining a mechanical gravure aptitude and a Ballard separation aptitude that have not been determined by a conventional Vickers hardness evaluation method.SOLUTION: By the determining method, the mechanical gravure aptitude and Ballard separation aptitude are determined from tensile strength and elongation percentage of a stress-elongation curve obtained when a copper piece in a dumbbell shape obtained from copper-plated coating is pulled at a fixed speed by a tensile tester until the copper piece is ruptured instead of management using indentation hardness, such as conventional Vickers hardness.

Description

  The present invention relates to a method for determining the mechanical engraving aptitude of a copper plating film on the surface of a gravure cylinder and the ballad peeling aptitude at the time of release.

An overview of the printing plate manufacturing process in gravure printing is shown in Fig. 1.
First, the surface of the base copper of the cylinder (gravure printing plate cylinder) whose surface (outermost layer) is copper (underlying copper), intermediate layer is nickel, and the closest layer to the core is iron or aluminum is prepared by polishing, etc. (Step S1).

  Thereafter, a ballad stripping solution for forming a release layer is applied to the cylinder surface (step S2), and then copper plating is performed to form a copper plating film (step S3). After copper plating, a number of depressions called cells are formed in the copper plating film by a mechanical engraving method (step S4) or a corrosion method (step S5).

  After the formation of the cell, the copper plating film on the cylinder surface is subjected to chromium plating in order to provide printing durability in the gravure printing process (step S6), and the gravure printing plate is completed (step S7). The completed gravure printing plate is used in the gravure printing process (step S8).

  Here, the reason why the release layer is formed before the formation of the copper plating film is that the copper plating film can be peeled and removed at the time of the release after the gravure printing process. The copper plating film peeled from the base copper of the cylinder (step S9) is called a ballad.

  The cylinder for which the peeling process is completed returns to the surface preparation (step S1) process of the base copper again and is reused. As described above, when the release layer is formed before the copper plating film is formed, there is an advantage that the labor of cutting the base copper of the cylinder can be saved and the cylinder can be reused.

  In the mechanical engraving method, the surface of the copper plating film is engraved with a diamond needle to form a large number of cells at positions corresponding to the pattern to be printed. The mechanical engraving method is characterized in that the density of the color can be expressed by the cell diameter and the plate depth, so that the light part is stably deposited during printing, and a printed matter with gradation can be obtained.

  In order to obtain a copper plating film having mechanical processing suitability suitable for the mechanical engraving method, it is common to use a copper sulfate plating bath to which various additives are added.

  Additives (additives) to copper sulfate plating baths for obtaining copper plating films with the above-mentioned mechanical workability include brighteners and polymers for the purpose of improving surface gloss, and improved leveling In addition to the leveler for the purpose, there is an additive called a hardener for ensuring physical properties suitable for mechanical processing.

  As a physical property evaluation method regarding the mechanical engraving aptitude of a gravure printing plate, a method based on indentation hardness such as Vickers hardness of a copper plating film has been conventionally performed. In the evaluation based on the Vickers hardness, an appropriate range of the copper plating film to be engraved is about 180 to 230. However, in the copper sulfate plating bath without the hardener, this Vickers hardness value range is realized. It was difficult.

  In the case of a copper plating film whose Vickers hardness is smaller than the above-mentioned appropriate range, phenomena such as the cell size becoming larger than the target size, the cell shape being destroyed, and the occurrence of burrs are observed. Therefore, the judgment by the evaluation method of the Vickers hardness is generally appropriate.

  As a means for managing the additive, a visual evaluation by a Hull cell test is simply performed. Although this evaluation method can estimate the degree of additive consumption by changing the gloss range, it is not suitable as a method for quantitative evaluation.

  For direct quantification of the concentration in the bath, the cyclic voltammetric stripping method, high-performance liquid chromatography method, ion chromatography method, capillary electrophoresis method are used industrially only for part of the leveler and brightener components. (For example, refer nonpatent literature 1, nonpatent literature 2, and patent literature 1.).

  On the other hand, with regard to the direct determination of the concentration of hardener in the bath, there is a conventional technique in which analysis and management are performed by paying attention to the addition concentration of the organic nitrogen-containing polymer that is one component of the hardener (Patent Document 2). However, an analytical method capable of directly quantifying the concentration of hardener in the plating solution containing various additives has not yet been established.

  At present, when a certain amount of hardener is added, it is measured how much the Vickers hardness of the copper plating film increases, and the concentration of the hardener in the bath is estimated, thereby controlling the amount of hardener added. It is.

  In the region where the concentration of the hardener in the bath is relatively low, the Vickers hardness of the copper plating film increases at a predetermined rate as the concentration of the hardener in the bath increases. It is possible to apply.

  However, in the region where the hardener concentration in the bath is high, there is a region where the Vickers hardness of the copper plating film hardly increases even if the concentration of the hardener in the bath is increased. In such a hardener high-concentration region, it is difficult to apply the hardener addition amount management method as described above, and therefore, measurement accuracy is insufficient for judging the mechanical engraving suitability of the copper plating film, Could not be used.

  When the hardener is added to an appropriate value or more, there is a problem in that defects in the appearance of the plating film such as abnormal gloss and flaw-like defects occur.

  Further, when the copper plating film is abnormally hard, there is a problem that the degree of wear of the engraving needle is increased and the life of the engraving needle is shortened. Further, during engraving, there was a problem that engraving needles were lost and normal cells could not be formed, resulting in damaged plates.

  Furthermore, when a hardener is added more than an appropriate value, the malleability and ductility of the copper which comprises a copper plating film (and ballad) will be lost. In such a case, when the ballad is pulled off at the time of release, there is a problem that the ballad cannot be peeled off to the end and is cut off in the middle, so that it takes time to peel off the ballad. This ballad peelability could not be judged by the conventional evaluation method using Vickers hardness.

JP 2004-53450 A Patent No. 4432422

Hideto Otani, “Analysis of Electrolytic Copper Plating Solution Using CVS Analyzer”, Surface Technology, Surface Technology Association of Japan, April 2003, Vol. 54, No. 4, p. 278-280 Hiroko Yanai, “Principle of Capillary Electrophoresis Device and Analysis of Plating Solution Composition”, Surface Technology, Surface Technology Association, April 2003, Vol. 54, No. 4, p. 263-267

  The present invention has been made in view of such conventional problems, and the problem is that the mechanical engraving aptitude and the ballad exfoliation aptitude of the copper plating film that could not be judged by the conventional evaluation method based on Vickers hardness. It is to provide a method of judging.

  In order to achieve the above object in the present invention, first, in the invention of claim 1, in a method for judging suitability for mechanical engraving of a copper plating film on a cylinder surface subjected to ballad plating used for gravure printing or the like, A method for judging the suitability of mechanical engraving from the tensile strength and elongation of the stress-elongation curve obtained when a dumbbell-shaped copper piece obtained from a copper plating film is pulled at a constant speed with a tensile tester. It is a thing.

  According to a second aspect of the present invention, in the method for judging the ballad peelability of the balladed copper surface used for gravure printing or the like, a dumbbell-shaped copper piece obtained from the copper plating film is used. This is a method for judging ballad peeling suitability from the elongation of the stress-elongation curve obtained when the tensile tester is pulled at a constant speed until it breaks.

  Since this invention is the above structure, there exist the following effects.

  That is, according to the invention according to the above claims, from the tensile test physical properties of the plating film, the evaluation of the physical properties of the copper plating film is replaced with the indentation hardness such as the conventional Vickers hardness. Since the tensile strength and elongation rate obtained from the characteristic values of the elongation curve are used, more detailed information that cannot be recognized by the indentation hardness can be obtained. This information makes it possible to judge the engraving suitability of the copper plating film.

  Further, the ballad peelability, which has not been known only by the Vickers hardness, can be judged from the elongation obtained by the tensile test.

Ultimately, by controlling the tensile strength and elongation obtained by the tensile test and controlling the amount of hardener added according to the value, a copper plating film with good mechanical engraving suitability and ballad peelability can be obtained. Could be manufactured.

Explanatory drawing of the manufacturing process of the gravure printing plate. Top view of dumbbell-shaped ballad copper piece Graph showing an example of stress-elongation curve Graph of change in tensile strength for each week in Example 1 Graph of change in weekly growth rate in Example 1

  Embodiments of the present invention will be described below.

  First, a copper plating film is formed on the surface of the cylinder. A copper sulfate plating bath is used as the copper plating bath for forming the copper plating film. Unless otherwise noted, the composition of the copper plating bath is that in which copper sulfate pentahydrate 200-240 g / L, sulfuric acid 40-80 g / L, and sodium chloride 180-240 mg / L are dissolved in ion-exchanged water. Those added with various additives are used.

Table 1 shows a list of typical copper plating additives added to the copper plating bath.

  After the formation of the copper plating film, the ballad is peeled from the cylinder, and a dumbbell-shaped test piece (see FIG. 2) is cut from a part of the ballad. After measuring the thickness of the ballad specimen, a tensile test is performed at a constant speed of 0.006 m / min, and the tensile strength and elongation are read from the obtained stress-elongation curve. Here, the elongation percentage is a value obtained by dividing a value obtained by extending the test piece until the test piece is broken by the original length of the test piece.

  An example of the stress-elongation curve is shown in FIG. In FIG. 3, the elongation range A and the tensile strength range B are management ranges for judging the mechanical engraving suitability and ballad peeling suitability of the present invention. If it is within the range B, it is determined that the mechanical engraving aptitude and the ballad peeling aptitude are appropriate.

  When the elongation percentage is smaller than the management range A or the tensile strength is larger than the management range B, it can be determined that the copper plating film is very brittle and hard and has no mechanical engraving suitability and ballad peelability. When the elongation percentage is larger than the management range A or the tensile strength is smaller than the management range B, it can be determined that the copper plating film is soft and sticky and has no mechanical engraving suitability.

  Specific examples of the present invention will be described below. However, the present invention is not limited to the following examples.

  Add the additive (Cosmo G) manufactured by Daiwa Special Co., Ltd. shown in Table 1 to the solution controlled to have a copper sulfate concentration of 200 to 240 g / L, a sulfuric acid concentration of 40 to 80 g / L, and a chloride ion concentration of 90 to 130 mg / L. The gravure cylinder was plated with copper while keeping the bath temperature at 45 ° C. There are two types of Cosmo G manufactured by Daiwa Special Co., Ltd., Cosmo G1 including a hardener and Cosmo G2 including a brightener. Since each additive is consumed by electrolysis in the bath, a certain amount is replenished according to the amount of energization.

  Test plating is performed every week, and the obtained copper plating film is peeled off to produce a ballad. The ballad specimen was cut and a tensile test was performed by the above method to obtain a stress-elongation curve. If the obtained copper plating film is very hard outside the control range, the supply of Cosmo G1 is temporarily stopped and excessive hardener components are consumed, and then the supply of Cosmo G1 is reduced from the previous time and the supply is resumed. . In this way, the optimum replenishment amount of Cosmo G1 in which the tensile strength and elongation in the stress-elongation curve are stable was sought.

The tensile strength in the weekly tensile test is shown in FIG. 4, and the elongation is shown in FIG. Each graph is partially enlarged so that the weekly changes in tensile strength and elongation can be easily understood. Table 2 shows the amount of cosmo G1 replenished every week and the loss rate due to missing engraving needles. The loss rate is the ratio of the number of damaged plates due to missing needles to the number of cylinders produced.

  When Cosmo G1 is replenished at 80 ml / kAh, it can be said that the copper has a high tensile strength and is harder than appropriate. Further, the ballad peelability was not good.

  When the replenishment amount of Cosmo G1 was gradually decreased, the tensile strength and the elongation were stabilized after the 11th week when the amount was 50 ml / kAh, and were within the control range indicated by the arrows. As can be seen from Table 2, the loss rate due to chipping of the engraving needle also decreased to 0.33%. Moreover, the ballad peelability was also good.

  INDUSTRIAL APPLICABILITY The present invention is used for stabilization of the surface appearance and mechanical engraving suitability of a copper plating film of a gravure cylinder widely used for the first time in the fields of publishing, packaging and building materials, and stabilization of ballad peelability.

A: Elongation rate management range B: Tensile strength management range

Claims (2)

  In a method for judging the mechanical engraving suitability of a copper plating film on a cylinder surface subjected to ballad copper plating used for gravure printing, etc., a dumbbell-shaped copper piece obtained from the copper plating film is obtained with a tensile tester. A method for judging the suitability of mechanical engraving from the tensile strength and elongation of the stress-elongation curve obtained when it is pulled until it breaks at a constant speed.   In a method for judging the peelability of ballad copper on a cylinder coated with ballad copper plating used for gravure printing, etc., a dumbbell-shaped copper piece obtained from the copper plating film is obtained at a constant speed with a tensile tester. A method of judging ballad peelability from the elongation of the stress-elongation curve obtained when pulled until it breaks.