UV imitation metal etching ink (frosted ink)
UV imitation metal etching printing makes use of the defects in UV imitation metal etching ink, which are caused by impurities, to scatter light. This is a defect that should be avoided in printing. However, if a large amount of “impurities” are added to the ink, and these small particles are printed on gold and silver cardboard with a metallic mirror shine using imitation etching screen printing, a special effect can be created that looks like smooth metal that has been corroded or treated with an engraving-style matte finish. The optical principle behind the special visual effect created by UV imitation metal matte printing is that when the printed image with UV imitation metal matte ink under direct light, the small particles in the ink diffuse the light, creating a strong contrast, giving the impression of a smooth metal surface with a matte finish; the parts without ink, due to the high gloss of the gold and silver cardboard, create a mirror-like reflection and give the impression of a raised surface. It still has the metallic luster of gold and silver cardboard. It can give the substrate a metallic luster and a three-dimensional relief effect like that of an etching, creating a frosted, matte, or chemically etched effect. The result is an elegant, dignified, and beautiful printed product that greatly enhances the decorative quality and artistic appreciation value of the printed product.
There are three methods for creating imitation metal etching printing:
Sandblasting: An uneven steel mold is used to heat and shape the substrate under high pressure to create a frosted effect.
Flat sandblasting: For the part of the pattern to be sandblasted, first use an etching solution to perform a matte finish. After drying, use a prefabricated mold with an uneven pattern similar to sandblasted glass to press the pattern area while heating it to set the molded uneven pattern in place by heat fusion, and obtain a sandblasted pattern after demolding.
Sandblasting: This is the most widely used method of imitation metal etching printing. It involves directly using screen printing to apply UV imitation metal etching ink to materials with a mirror-like sheen to achieve a frosted effect.
UV imitation metal etching ink is a kind of colorless, transparent, single-component UV screen printing ink with a particle size of 15–30 μm. The ink has short, thick filaments, and “sand” particles with a diameter of 15–30 μm are added to the ink. After printing, the ink forms a matte effect due to diffuse reflection in light. The so-called “sand” particles are actually fine, colorless and transparent plastic particles, such as polypropylene, polyvinyl chloride, polyamide and other plastic powders, as long as they meet the particle size of 15–30 μm. In order to reflect the inherent luster of the substrate, UV imitation metal etching inks are generally a light-colored transparent paste made by stirring together various materials such as oligomers, reactive diluents, photoinitiators, and fillers. Pigments can also be added to make colored etching inks, but pigments with strong covering power should not be used. A UV imitation metal etching ink with superior performance must first have good particle distribution and a sense of three-dimensionality, and produce good etching effects. It can only produce satisfactory artistic effects after printing. It must also have excellent adhesion and flexibility, otherwise it will burst during the rolling seam process of cigarette and wine boxes, seriously affecting product quality. It also needs to cure quickly, have a long shelf life, feel good to the touch, and not be too rough, otherwise it will easily cause sheet rolling in the packaging production line of cigarette labels. In addition, the ink used to print cigarette labels and food packaging boxes must also have low odor to ensure that the ink meets the requirements of food hygiene and environmentally friendly green printing. UV imitation metal etching ink When mixing the ingredients, all additives and materials must be thoroughly stirred to ensure homogeneity. To reduce the leveling of the ink on the substrate film after printing, the use of leveling agents should be minimized or avoided to promote the formation of a rough surface. In addition, the formulation design should ensure that the pseudo-metallic etching ink has good thixotropy and suitable adhesion, and the ink viscosity should be adjusted and controlled according to different substrates and equipment environments.
When printing with screen-printed UV imitation metal etching inks, the choice of screen is crucial. The mesh count of the screen selected should match the thickness of the ink sand mold. If the ink sand mold is relatively thick and has a large particle size, a screen with a lower mesh count should be selected. screen, which has larger pore size, can allow the sand particles in the ink to pass through the screen and be printed onto the substrate. Otherwise, some sand particles will remain on the screen, resulting in sparse sand particles on the printed matter, a whitish appearance, and poor etching effect. Moreover, as printing progresses, the ink sand particles will continue to accumulate, and the ink viscosity on the screen will gradually increase. If the sand mold is finer and the particle size is smaller, a screen with a higher mesh count can be selected. Generally, the diameter of the ink sand particles is 15-30μm, and a screen mesh with 150-250 mesh can be selected. The specific situation can be selected based on actual usage experience.
In order to achieve a good visual effect of UV etching printing, the choice of substrate is also very important. Generally, materials with a metallic mirror effect and high gloss are selected. The smoothness of the material is also very important. If the smoothness is low, the printability will not be high and the ink adhesion will be poor. Cardboard with aluminum foil vapor-deposited or aluminum foil can be printed, but gold and silver cardboard is most ideal.
It is important to be familiar with and master the printability of UV imitation metal etching inks in printing. Generally speaking, problems will arise when UV imitation metal etching inks are used in high-volume, high-speed production on a fully automatic screen printing machine. Often, after printing a few thousand or tens of thousands of sheets , the imitation metal etching ink cannot spread completely and densely on the screen, resulting in an uneven imitation metal etching effect; if the UV imitation metal etching ink is too thin or has poor compatibility, it is easy to cause bleeding or showing the backing. To avoid these problems, the first thing to do is to use gold and silver cardboard that meets quality requirements, because for some relatively poor quality gold and silver cardboard, the UV imitation metallic etching ink will dissolve the gold and silver colors on the gold and silver cardboard, and in severe cases, even dissolve all the gold and silver colors, making the entire print look white. To solve this problem, when designing the ink formula, it is necessary to take into account the composition of various raw materials as a whole, and not to use reactive diluents with a small molecular weight and strong solubility, in order to avoid color fading of the gold and silver cardboard. Of course, increasing the intensity of the UV light source and shortening the time from printing to curing the printed matter will also have some effect on overcoming the problem of the printed matter turning white.
How can a matte effect be achieved with UV curing inks? This can be achieved by adding micronized wax or inorganic matting agents. Wax is a very common component in inks, used to change the rheological properties of the ink, improve water resistance and printing performance, and make the printed dots even and complete. Microcrystalline wax is generally synthetic polyethylene wax or polypropylene wax, dispersed in UV screen printing inks. When the ink cures to form a film, the wax is incompatible with the resin system and therefore floats free on the surface of the cured ink film, affecting the gloss and creating a matte effect. This matte effect has a soft feel and a waxy texture, but because the wax powder simply floats on the surface of the printed film to create a matting effect, and because the wax itself has low strength and poor scratch resistance, the effect is mostly unsatisfactory. If you use an inorganic filler component such as fumed silica, silicon powder, or talcum powder instead, it will be difficult to achieve a matte frosted effect because of its poor ability to float on the surface of the film.
For UV inks with added silica matting agents, a stepwise irradiation method can be used to achieve a matte frosted effect. First, the wet ink layer is irradiated with a light source of longer wavelengths. Because of its strong penetrating effect on the film, it can basically cure the underlying ink. Although the surface layer of the ink layer has relatively strong light energy, it is disturbed by oxygen inhibition, and the upper surface layer is poorly cured. a structure of dense lower layers and sparse upper layers is formed, which has the effect of forcing the fillers to float upwards. This, combined with the incomplete compatibility of the inorganic fillers (silica) with the organic cross-linking network, causes the inorganic particles to migrate towards the surface layer, where curing is less effective, and accumulate on the surface of the ink layer. At this point, the ink layer is irradiated with a light source of shorter wavelength and higher energy to completely cure the surface layer of the ink, so that a distinct matte frosted effect can be achieved.
Contact Us Now!
If you need Price, please fill in your contact information in the form below, we will usually contact you within 24 hours. You could also email me info@longchangchemical.com during working hours ( 8:30 am to 6:00 pm UTC+8 Mon.~Sat. ) or use the website live chat to get prompt reply.