Because the UV ink has the advantages of fast drying, small footprint, energy saving, good stability on the screen plate, no pollution to the environment and the like, it is the development trend of the ink, and will also be the type of ink mainly used in advertising printing in the future. However, when the solvent ink is turned to the UV ink, since the solvent is not volatilized after the UV ink is printed, the thickness of the ink layer is seldom thinned after drying, so under the same printing conditions, the ink thickness of the UV ink is more than twice as thick as the solvent ink. , For monochrome printing, will not cause any effect, but for dot printing, when printing the third color or the fourth color, especially the fourth color, due to the color overlay, the ink layer is significantly thickened, resulting in the substrate The surface is uneven, under certain squeegee pressure, the ink diverges to the low concave place, causes the network point to expand. The hue distortion caused by dot enlargement occurs, and the solvent-based ink thins due to a large amount of solvent volatilization. At the same time, in the overprinting, the solvent of the latter layer of ink penetrates into the ink of the previous layer, and most of the solvent evaporates. The thickness is reduced by more than half, so it will not be as thin as the UV ink, and the thickness will be thinner. Therefore, the UV ink will diverge when the ink layer is overprinted.
In order to solve this problem, the United States NAZDAR company Sanhe International agents after years of meticulous research and development to solve the problem of ordinary UV ink dispersion in the process of printing the new ink - water-based UV ink HU000 series. Its characteristics and using techniques are briefly described as follows:
1, because it contains water and 5% of environmentally friendly solvents, water evaporation after curing, the ink layer thinning, so it not only has a solvent-based ink drying ink thin, but also UV ink drying fast, environmental protection and other advantages.
2, for modern printing equipment, low curing energy, can reduce costs and reduce substrate love hot, hard surface after curing. With a high-density dot color, suitable for indoor and outdoor advertising, such as backlighting advertising and pre-light advertising, bright colors, high-definition, no shadow on the periphery of the network. In particular, the printing of the fourth color has a very good sharpness effect.
3. It is a one-component photocurable ink without NVP or heavy metals.
II. Process Parameters of HU000 Series Waterborne UV Photocurable Inks
1, process parameters. Substrates: Synthetic paper (such as YUPO), PS, hard PVC, vinyl, paper and cardboard. Wire mesh: 140-150 mesh/cm monofilament polyester mesh. Screen: solvent-resistant emulsion or thin film. Scraper: 70-90Â°. Auxiliaries: HU180 thinner, HU193 regulating paste, HU349 thinner, HU350 mesh oil.
2, printing techniques.
1HU series is used in the back light advertising field, with high color density, can be added HU350 spot oil to adjust the color density, if you need to adjust the viscosity and leveling, you can add about 8% of U193 control cream or about 2% of HU180 thinner . However, the ink should be fully stirred before printing.
The 2HU series has two kinds of red dots (a kind of partial blue, a kind of partial red), two kinds of dots (a kind of greenish, a kind of red), blueish, greenish, and warm red. How to use two red and two yellow? There are many kinds of white background, yellowish, blue, the same color printed on different kinds of substrates have different effects. If the substrate has been yellow, you should choose yellowish bias, reddish blue; if the substrate is blue, you should choose reddish yellow and reddish red.
If the substrate is cold, you should choose to warm; if the substrate is warm, choose cold. The same picture, printed on different substrates, to achieve the desired effect, should choose different colors of dot ink.
In general, if you print trees and other natural scenery, choose greenish yellow and bluish red; if you print characters and foods, especially warm colors such as swimsuits and sun sets, use reddish yellow, reddish red, etc. Warm colors are better.
3, curing. Medium pressure mercury lamp with focus mask, 200w/in, transmission speed 20m/min
Third, pay attention to matters
1, the ink must be thoroughly stirred before use.
2, if the ink layer is still not thin enough to cause the network to expand, you can add HU349 thinning agent in the first color, the second color.
3. Under the same printing conditions, since the UV ink is thicker than the solvent ink layer, process adjustments can be made to the dots of the negative film before screen printing, or when screen printing is performed, select a higher mesh screen or select Single-sided flattened wire mesh for UV inks.
4, photosensitive layer requirements on the screen. 1 Use thin capillary photographic film or indirect five-star red photographic film to make the screen. 2 When photosensitive screens are used to make screens, in addition to using yellow PET screens, the thickness of the photosensitive adhesive layer and the unevenness of the surface should be controlled to <4 Î¼m to improve the sharpness of the dots.
5. Test the printing conditions before use. Test the properties of the ink after printing for 24 hours.
Reprinted from: China Printing and Packaging Network
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