UV printing ink layer is not strong phenomenon (2)

Incomplete drying of the ink will cause the ink layer to fall off during the subsequent processing. If the ink is dried too much, it may cause the ink layer to fall off. In a printing factory, there has been such a case, the customer after the printing of the die on the die-cutting machine, because it is bleeding die-cutting saw die cutting edge of the ink sawtooth off. The print is folded and the ink flake off. Later, it was found that the excessive drying of the ink caused by the high UV lamp power during printing caused the dried ink layer to become very fragile and eventually caused the edge of the ink extension die to jagged off during die cutting.

Excessive drying of the UV ink will cause the ink layer to fall off in addition to the UV light oil in the sequence. There are many printing plants that have appeared on the surface of the product when the printed job is printed with UV varnish. This is due to the over-smoothing of the surface of the print after the crystallization of the UV ink. The surface tension is greatly reduced and the UV varnish shrinks on the printed surface. When this type of problem is encountered, a layer of undercoating ink can be printed on the surface of the printed matter, or a layer of ink remover can be printed to increase the surface tension of the product. Then, after applying UV varnish, the oiling effect can be greatly improved.

Fifth, the uneven ink mixing causes the ink layer to fall off

It is believed that many people know that ink is not composed of one kind of substance, and there are many ink auxiliaries in addition to pigments. When the ink is left unused for a period of time, various additives and pigments in the ink will form different free layers due to their own density. When we use these inks for printing, we must first evenly mix the inks, otherwise there may be problems.

There was a case in which a printing factory reported that the ink did not dry when printed. The performance phenomenon is that the ink on the printed material falls off into a powder, and increasing the power of the UV lamp is also not effective. As a result, it was found that the ink in the ink fountain was taken out and placed in an ink cartridge and mixed with other inks before being printed and everything was normal. This shows that the ink contained in the ink fountain contains too many pigment components, resulting in the ink powder falling off after printing. Through this case we can know that it is important to evenly mix the ink before printing.

Six, film material and ink matching

Those who have experience in printing know that in fact, the poor ink drying during the printing process mainly occurs when printing film products, and the poor printing ink dryness is relatively small. This is mainly due to the relatively low surface tension of film products, and the ink is not easily attached to the surface of such products. For film products, the surface tension must reach 38 dalters or more to combine with the ink. For this phenomenon, raw material suppliers mainly perform two kinds of processing on such materials to increase the surface tension of the material before the film product is shipped. The two methods are corona treatment and coating treatment, respectively.

The so-called corona treatment is: discharge through the high voltage charge to the film surface, under the action of ionization, the film surface is roughened, the surface energy is increased, the ability to combine with the ink is increased, and the purpose of strengthening the firmness of the ink layer is achieved.

The so-called coating treatment is: the surface of the film is coated with a special coating in the manufacturing process in order to improve the surface tension of the film and strengthen the binding force of the film with the ink.

The corona treatment costs are lower in these two methods, but corona-treated materials have poor surface tension stability. As time increases, the corona effect will gradually decrease. Especially when stored under high humidity conditions, the corona effect is reduced more quickly. Therefore, in order to achieve a good printing effect in the actual printing process, it is recommended that the corona treatment material be subjected to on-line corona treatment by the printing factory. The material treated by the surface coating has relatively high relative corona treatment cost, but its advantage is that the effect is very stable and the surface tension is not influenced by time.

When the printing plant prints film products, the phenomenon of poor ink drying occurs. You can use a tone pen to test whether the printed material reaches 38 or more. If the surface tension of the material exceeds 38 Da Yin's ink, or if it cannot adhere firmly to the surface of the material, ink replacement should be considered. For some of the larger UV ink suppliers, the ink is often divided into many series, each series has its own characteristics. Some of these series are designed to print thin film materials. When necessary, thin film products can be used to print thin film products. For thin-film products with a surface tension of less than 38 megatons, the on-line corona process mentioned above can be used for printing. For printers without on-line corona devices, the surface tension of the material can be increased by applying a primer to the material first, and then printing can be used to solve the problem. Primer inks are available from UV ink suppliers.

Seven, the ink color of the ink drying effect

Experiments have shown that the absorbance of the spectra of various colors of ink is different, resulting in different degrees of drying of different colors of ink under the same power UV lamp. White reflects light directly, black reflects diffusely, and red absorbs light better. Therefore, according to the different colors of the drying characteristics of a reasonable arrangement of the printing color sequence will not dry the first printing of a good dry after printing can also be to a certain extent to solve the problem of poor ink drying.

These are some of my experiences with the insecure UV printing ink layer and poor ink drying problems. I hope to be able to help everyone in daily production. I believe that in the future when we encounter such problems, we can find out the cause of the problem by analyzing the problems arising from the above-mentioned experience. It will be helpful to eventually solve such problems and avoid the occurrence of such problems.