Confused background: For my mind, there is a mystery that I can't unravel, and once, in the UV printing process using light gold paper and white ink, occasionally there is a bit of ink at the bite. When the power of the UV lamp was adjusted from 60% to 80%, the phenomenon of pulling ink was aggravated and the power was adjusted back to 60%. The situation became better. I have no idea why.

Editor's note: We believe that you have had the same or different confusion with Tiger Colors during the production and printing of packaging. How is it solved in your actual operation? Or do these problems continue to bother you? I hope that after reading this edition, we will treat our columns as a platform for technical exchanges and tell them about these confusions. Going out of confusion here is exactly the original intention of this edition.

As the name implies, the ink printed on the back pulls the ink in the front seat. There are two kinds of ink-pulling phenomenon in tiger color: one is ordinary printing ink, and the other is UV ink printing, wherein UV ink includes white ink and ink.

Since the end of 1998, six-color computer has shifted from ordinary printing to UV printing. The first worksheet is "Red Flag Canal". The ink used is Gao's UV ink. The customer complains of yin and yang (color changes at different angles). Later it was gradually transferred to tiger head UV ink. Its performance was good and there was no ink pull phenomenon. After a period of time, in order to reduce the material cost, the company switched from Hangtou ink to Hanghua ink (Tiger head ink price higher than Hanghua ink). After that, with the change in the product structure of the company, from ordinary gold cards to light gold printing, there was no white ink to make a transition to white ink. Some of the products were changed from the first printing to the first hot printing. The structure of the product became complicated. As a result, the phenomenon of pulling ink has obviously increased. At that time, the personnel at the station were frightened and had no way of starting. The workshop leaders did not have a better way to solve the problem. The only thing that was doubtful was the ink because Hanghua ink had replaced the tiger head ink. It will be decided by the Procurement Department to inform the ink supplier to come to our company to help find out the reason. Therefore, Mr. Zuo Youyi, a Japanese ink expert from Donghua, came to our company to analyze the reasons. He made several observations: 1. Hanghua and the Tigerhead ink Made for Japan's Tung Wah Ink Co., Ltd., but the packaging is not the same. 2. Change the binder of the ink to reduce the viscosity, the ratio of the pigment to the binder is not adjusted (volume ratio), and if the pigment is less than the binder, the viscosity of the ink is small. 3, the inconsistent shape of the pigment and the condensation of the ink particles also have an effect on the viscosity of the ink. 4, the temperature is too high or too low will also affect the viscosity of the ink. 5, the speed of the printing press, due to the inertia of high-speed machines, so the viscosity of the ink should be reduced accordingly. Mr. Zuo Youyi analyzed and discussed the above five points. Finally, he provided a GW ink instead of 161 white ink. After trials, he basically solved the situation of pulling ink. However, the good times did not last long. It took about 2 months, and the phenomenon of pulling ink came again. The emergence, even more and more serious, forced helpers, but also inform the Hanghua ink engineers to deal with the scene.

Mr. Sato Koichi came to our company for the second time and called the technical department, printing press staff, ink reviser and printing manager, and the director to hold a workshop to address the company’s existing product structure and quality standards. The company specially developed an explosion-proof and folding-resistant HZ ink for Hucai, and its anti-pulling performance was also very good. About May last year, the phenomenon of pull-ink began to appear again. Sometimes it was mild, sometimes very serious, and there was no regularity. At that time, it was suspected that the quality of the ink was unstable and led to ink-pulling. However, after repeated tests, it was confirmed that the ink quality was relatively stable. Later, when the new UV lamp was replaced, the power was maximized and there was a situation where the ink was drawn. Like the “Amazing Century Dragon” and “Authorized Emei Mountain”, the white ink was printed on the light gold. The phenomenon of pulling ink was more serious and it took a long time to find it. Reasons: Replacement of different papers for testing, concluded that light gold is easier to pull ink than ordinary gold paper, but there is no tool to detect the adhesion of paper, often to solve the pull ink, sometimes it takes a day (24 hours), Even longer. Ke Tang repeatedly told the manufacturing department several times that a machine will produce less than 30,000 productions a day in two shifts a week. The sales department also repeatedly mentioned that delayed delivery time affects customers. Quality control department suffers from negative inspections and product quality. Unstable, even leaked to the customer, giving the customer a bad impression. Low output If the machine itself does not fail, it is operationally difficult. Such as: to solve the pull ink, it is not only operational problems, but also material problems. Until the end of May 2000 to Shenzhen to participate in printing technology training, ISTUV experts to provide a test of the surface tension of the gold paper pen, after a period of time tested and summarized: ordinary gold cardboard, light gold paper, silver cardboard, the surface tension is low In 34 dyne, it is easy to pull ink, the surface tension reaches 36 dyne, basically no pull ink, the quality control department requested the paper supplier to provide qualified paper with this data standard, and once the supplier provided "refined month free spring 》Light-silver paper, the machine is very serious when printing ink, change the ink of different brands, reduce the viscosity of the ink, adjust the printing pressure, replace the UV lamp, can think of ways to think, but can not solve the ink, Finally, using a surface tension pen to test, only 34 dyne, and the surface of the paper electrostatic film, the results of this batch of paper surface varnish treatment completely solved the pull ink.

In addition to paper, ink, and UV lamp power factors, the actual operation of the machine also has a lot of factors. I'll give two examples here: Example 1. The six-color machine will be printing the "Black Treasure Box" one evening at a time. The phenomenon of serious ink-pulling was caused by the repeated adjustment of the color seats by machine personnel. The result was unable to be resolved for about 13 hours in the evening. On the morning of the second day, both the machine shift and the director's handover class mentioned that the surface tension of the paper could not be reached. Requested, and stressed that the paper returned to the supplier, after the succession of the day shift, the first white ink was reduced, the back of a few colors of water increased, while the pressure behind the several seats reduced, and the result was resolved. In the second case, in October 2001, the old five-color machine was printed "fine seabirds box", the number of feeds was more than 200,000, and about 100,000 heads were printed. The machine table put forward the situation of pulling ink, when the machine was suspected of UV The power of the lamp is not large enough, and it is a little strange to me to reflect it to me. The same UV lamp in the night shift has not seen the phenomenon of pulling ink. Therefore, the captain is required to check whether the back tape is used for a long time and the surface is uneven. Finally, the replacement is required. After the new tape, the phenomenon of pulling ink will be solved. However, there is a mystery in the mind of Lamo that has never been solved. I remember that in March 2001, a group of “Lanzhou Treasures” was sent to the Printing Factory in Dalingshan Changming for printing because the machine personnel there did not touch the golden ink and white ink. UV printing, for the ink is a stretch, by my cooperation to solve, UV light power is only open to 60%, I thought it was white ink did not completely dry, require the staff to open the UV lamp power to 80%, the results of the ink more Seriously, the power of the UV lamp was turned back to 60%. The situation has improved again. So far, I don't know what the reason is.

I have been puzzled by printing ink for two years. In the past two years, I have explored and analyzed UV inks, constantly summed up lessons learned, and now listed the relevant solutions:

First, the surface tension of the paper must meet the requirements, ordinary gold cardboard, light gold, silver and other surface tension to 35 dyne, white card glass paperboard must have a certain surface strength, that is, the surface strength of P ≥ X +U+N.
P-Fibre and the binding force between the filler and the glue X-ink adhesion to paper U-inertia force (stripping tension)
N-blanket adsorption force and viscosity Second, to master the UV lamp power, to understand the life of the UV lamp, a reasonable arrangement of UV lamp sequence.
Third, properly adjust the viscosity of the ink used, in the ink by adding a suitable amount of detackifier (departmental standard does not exceed 5%), in order to improve the adhesion of the ink to the paper.
Fourth, properly adjust the printing pressure, so that the pressure between the blanket cylinder and the impression cylinder can be reduced, or choose the appropriate printing speed, in order to properly reduce the speed is better, so that the peeling force between the blanket and the paper after imprinting It can be reduced.
Fifth, to ensure that the tape is smooth, if the surface of the tape is rough, the friction is great, and the tension is increased. If necessary, a new tape needs to be replaced.
Sixth, to control the ink and ink, it is necessary to consciously reduce the amount of water in front of the ink pad, and increase the water in the ink pad at the back.

(Humen Color Printing Co., Ltd. Zhang Chuanzhen)

Reprinted from ("Tobacco Wine Packaging Album")