1. What are the disadvantages of the traditional platemaking method when gravure printing is used for plastic packaging and printing?
The legal process of traditional legal plates is very complicated, and the variable factors in the process of plate making are also numerous, and often have the following disadvantages:
1 The plate making process is complicated, and most of them are manual operations, and it is difficult to realize data control;
2 The use of carbon paper overprint, plate accuracy is not high, can not print high-grade color prints;
3 can not achieve seamless plate-making;
4 is not technically stable and requires high operating skills;
5 The cost of plate making is relatively high.
Therefore, this method can only be applied to the printing of print products with low requirements for printing quality. With the higher and higher requirements for the quality of printed materials, this method of plate making has gradually been eliminated.
2. What is the purpose of chrome plating?
After the printing plate graphic is established, a layer of chromium is also plated, and the chrome plating is to increase the surface hardness and protect the printing plate roller so as to improve the plate printing resistance force. Because the chrome plating layer has strong hardness, abrasion resistance and chemical stability, it can make the surface of the printing plate roller have good mechanical strength and can keep the printing plate glossy for a long time.
Chromium plating electrolyte is mainly chromic anhydride and sulfuric acid. The key to electroplating is to control the current and electrolyte temperature. The temperature is generally controlled at 50-55°C. The plating process requires the best variation of ±1°C, and the temperature of the electrolyte should be uniform. When conditions permit, the current can be increased. The larger the current, the higher the hardness.
3, poor coverage in the printing plate chrome plating process, how to solve?
When the phenomenon of poor coverage in the chrome plating process of the printing plate occurs, if the content of sulfuric acid is too high, a suitable amount of BaCO3 can be used to reduce the content of sulfuric acid. If it is caused by a high level of metallic impurities such as trivalent chromium or iron, the content of trivalent chromium may be reduced or impurities may be removed by ion exchange.
4. What should be done when the local surface is not plated with chromium in the chrome plating process?
In the chrome plating process, when the partial surface is not plated with chromium, if the temperature is too high, it is necessary to properly reduce the temperature. If there is an oxide film or oil on the surface of the plated part, the chromium plating must be strengthened. If the current density is too low, increase the current density. If it is due to poor contact, etc., check and clean the contact points.
5. What should be done when the hardness of the chrome plating layer is low and dark gray in the chrome plating process?
In the chrome plating process, the chrome plating layer often has low hardness and dark gray color. If it is due to improper temperature and current density, it should be adjusted to the normal range. If the sulfuric acid content is too small, it is necessary to analyze and adjust the sulfuric acid content.
6. What should be done when the edge of the plate is black or dark in the chrome plating process?
In the chrome plating process of the printing plate, the edge of the coating often appears dark or dark gray. If the current density is too large, the current density needs to be reduced. If the temperature of the electrolyte is too low, it is necessary to increase the temperature of the electrolyte. If the current is too high when the roller enters the slot, it is necessary to control the current density when the roller enters the slot.
7. How to deal with the slow deposition of plating in the chrome plating process?
The slow deposition of plating in the chrome plating process may be due to poor electrical conductivity. The method of elimination is to check the conductivity of the cathode and anode.
8. What are the aspects of the quality of roller copper plating?
The quality of roller copper plating should be tested in the following ways:
1 After the copper plating, visually check whether the surface is smooth or not. The surface of the coating is required to be smooth, free from burrs, blisters, and peeling.
2 Check with a durometer to see if the hardness of the copper layer is within the specified range. If the hardness is too high, it is necessary to dilute the concentration of additives in the plating solution, otherwise it will be reduced.
3 Measure the thickness of the plating. This refers to the thickness of the plate copper layer, which requires a certain thickness, otherwise it will bring difficulties to the post-processing. Of course, the thickness is determined according to the post-processing method and the post-processing allowance.
9. What aspects of roller plate quality should be tested?
Roll plate quality should test the following aspects:
1 Check whether the register signal and gauge lines on the roller are correct.
2 After the roller plate is finished, it is best to use a dot detector to check the depth, midtone, dark tone, and high profile conditions of the lower dot.
3 check the roller size is correct.
4 Check whether the pattern arrangement is correct.
(Author/Cai Huiping Yuan Wei Liao Dazhi)
Guangdong packaging
The following issues should be taken into account when gravure plates are printed in soft plastic packaging.