Talk about the factors affecting the life of UV printing blankets

During the printing, many new processes and new technologies emerged. For example, UV printing has achieved good results. However, in use, some factories have experienced problems due to the mismatch between UV inks, UV-specific car wash water and UV-specific or dual-use blankets, which have caused many problems such as: printing effect, yield, and production cost. For example:

(1) The blanket bulges;
(2) A new blanket is needed to print the UV product for other prints;
(3) The printing dots are enlarged, and the ink particles are coarse and have poor gloss.
(4) The effect is not ideal for full-screen printing.

In addition, UV inks are extremely corrosive, and the rapid aging of the rubber surface affects the service life of the blanket, directly resulting in print quality. Therefore, to extend the life of the blanket must start from its own and supporting products.

UV blanket

Let's first look at the types of UV blankets.
Special UV blankets All the blankets are made of synthetic cyanide rubber. Although the synthetic rubber particles are fine and the dot reduction performance is good, the disadvantage is that they are not resistant to corrosion. The UV blanket not only contains EPDN, but also contains natural rubber because of its good corrosion resistance. UV blankets cannot be used for normal printing, and do not need to be replaced when changing different UV prints.

UV dual purpose blanket

Compared with the special UV blanket, it only contains low natural ingredients, but it can be used for both purposes. The so-called dual-use means that the ordinary printing can be changed to UV printing, but after UV printing, it may not be able to Normal printing is performed except for UV inks used for printing paper, or ordinary printing with little print. Although the life of the blanket is theoretically greater than 1 million impressions, in actual use, due to many external factors, such as: the operation of the machine, the corrosion of the ink, the choice of car wash water, the quality of the substrate, etc. will also affect its use. Longevity, such as the Shanghai Tobacco Industry Printing Factory's use of ConTITECH's UV-Black-specific air-cushioned blankets, typically ranges from 300,000 to 600,000 impressions.

UV ink

We can roughly classify UV inks into two broad categories.

UV inks that can only be printed on paper

This type of UV ink is less corrosive to blankets because it absorbs ink in time. This type of ink can use UV dual-use blankets. When the number of prints is not large, some printing houses use ordinary blankets instead.

Although UV inks for printing paper cannot be used for printing on plastic substrates, plastic printing UV inks can be used for paper. Many gold and silver cardboards have a thin film on the surface, so be sure to check the type of paper and ink when printing.

UV inks that can be printed on plastic

Due to the good leveling of the ink on the plastic, which will cause serious increase of the dot, it is necessary to add some polar solvent in the ink to destroy the surface tension of the film in order to absorb the ink. This makes the ink very corrosive. At this time, a special UV blanket is needed instead of a dual-use blanket, otherwise the blanket needs to be changed to print different prints. It is necessary to explain that, when using the ink, it is necessary to confirm with the machine manufacturer that the currently used rubber roller meets the requirements, because after a few months, the roller will stick, and the machine manufacturers often Think it is due to improper use of the machine.

UV car wash water

Improper matching of the ink and the blanket can cause the printed portion of the blanket to bulge. However, if ordinary car wash water is used for the UV blanket, the non-printed portion of the blanket will also bulge.
Therefore, whether the performance of the car wash water is matched with the blanket can also affect the service life of the blanket.
How to identify matching

Between UV inks, UV-specific car wash water and UV-specific or dual-use blankets, it is possible to detect whether they match each other through some tests. Test method for the matching of blanket and car wash water (ISO 12636 standard) First, pour the car wash water into a small glass bottle, cut the blanket into the size of the bottle cap, insert the bottle cap, and cover and flip the bottle upside down. Hours (make the rubber surface fully in contact with the car wash water). Then dry the blanket and measure the thickness of the blanket. Before and after the test, the blanket thickness difference cannot be greater than 0.02mm. The test method for matching the blanket and the ink (ISO 12636 standard) applies ink to the surface of the blanket, wipes the ink naturally after 24 hours, and measures the thickness of the blanket. The difference between the thickness of the blanket before and after the test can not exceed 0.02mm.

Reprinted from: Printed Materials in China