In printing, many new processes and new technologies have appeared, such as UV printing has achieved good results. However, in use, some factories have a phenomenon in which UV inks, UV-specific car wash water and UV-specific or dual-purpose blankets do not match, causing many problems with printing effects, yield, and production costs, such as:
(1) The blanket swells up;
(2) After printing UV products and changing to other printing products, new blankets are needed;
(3) The printing dots increase seriously, and the ink particles feel thick and the gloss is poor;
(4) The effect is not satisfactory when full-page printing.
In addition, UV ink is extremely corrosive, and the rapid aging of the rubber surface affects the service life of the blanket, which directly leads to print quality. Therefore, to extend the service life of the blanket, we must start from its own and supporting products.
UV blanket
First, let's understand the types of UV blankets.
Special UV blanket
All rubber blankets are made of synthetic cyano rubber. Although the synthetic rubber particles are fine and the dot reduction performance is good, its disadvantage is that it is not resistant to corrosion. The special UV blanket not only contains EPDN, but also contains natural rubber, because it has better corrosion resistance. The UV blanket cannot be used for ordinary printing. There is no need to replace the blanket when changing different UV prints.
UV dual-use blanket
Compared with the special UV blanket, it only contains low natural ingredients, but it can be used for two purposes. The so-called dual-use means: ordinary printing can be changed to UV printing, but after UV printing, it may not be Ordinary printing, unless it is UV ink used for printing paper, or ordinary printing with small printing volume. Although the life of the blanket is theoretically greater than 1 million prints, in actual use, due to many external factors, such as: machine operation, ink corrosion, choice of car wash water, and quality of the printing material, etc. will also affect its use For example, the life time of Shanghai Tobacco Industrial Printing Factory when using CONTITECH's UV-Black special air cushion blanket is generally 300,000 to 600,000 printed.
UV ink
We can roughly divide the UV ink into two categories.
UV inks that can only be printed on paper
This type of UV ink is not very corrosive to the blanket, because the paper can absorb the ink in time. This kind 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 ink for printing paper cannot be used for printing on plastic substrates, UV ink for plastic printing can be used for paper. Many gold and silver cardboards have a thin film on the surface, so be sure to confirm the type of paper and ink when printing.
UV inks that can be printed on plastics
Due to the good leveling of the ink on the plastic, it will cause the dots to increase seriously, so some polar solvents need to be added to the ink to break the surface tension of the film in order to absorb the ink. This makes the ink highly corrosive. At this time, you need a special UV blanket, and you can not use a dual-purpose blanket, otherwise you need to change the blanket to print different prints. It is necessary to explain that when using the ink, it is necessary to confirm with the machine manufacturer whether the rubber roller currently used meets the requirements, because the rubber roller will stick after less than a few months, and machine manufacturers often It is believed to be caused by improper use of the machine.
UV car wash
Improper matching of ink and blanket will cause the printed part of the blanket to swell. However, if ordinary car wash water is used for the UV blanket, the non-printed part of the blanket will also swell.
Therefore, whether the performance of the car wash water matches the blanket will also affect the service life of the blanket.
Ways to identify matches
Between UV ink, UV-specific car wash and UV-specific or dual-purpose blanket, through some tests, it is possible to detect whether they match each other. Method for detecting the matching of the rubber cloth and the car wash water (ISO 12636 standard) First, pour the car wash water into a small glass bottle, cut the rubber cloth to the size of the bottle cap, put it into the bottle cap, cover it and invert the bottle 22 Hour (make the rubber surface fully contact with the car wash water). Then dry the blanket and measure the thickness of the blanket. Before and after testing, the thickness difference of the blanket cannot be greater than 0.02mm. Method for testing the matching of blanket and ink (ISO 12636 standard) Apply the ink to the surface of the blanket, wipe the ink clean after 24 hours of natural placement, and measure the thickness of the blanket. The difference between the thickness of the blanket before and after the test cannot be greater than 0.02mm.
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