UV Ice Flower Ink
UV Ice Flower Ink is a special UV transparent ink. It is printed on a card with a mirror-like aluminized film using the screen printing process, and cured by ultraviolet irradiation. A crystal clear and evenly distributed ice flower pattern appears on the surface of the substrate, which shines dazzlingly in the light and makes the packaging more novel and unique. Ice flower ink is generally used for surface decoration of products such as product packaging, gifts, greeting cards, and labels. However, due to the disadvantages of UV ice flower ink, such as the long UV irradiation time required to produce ice flowers, low production efficiency, high energy consumption, and easy deformation of the paper, it is mostly only used for small batch printing and has not been widely used in the packaging industry. UV ice flower oil inks can also be printed on transparent substrates such as glass, transparent acrylic, transparent PC, etc., and are often used to reverse print positive views; they can also be printed on substrates with reflective effects, such as mirror stainless steel, titanium plates, mirror-finished aluminum oxide plates, etc.
UV frosting ink is a colorless, transparent, oily liquid. By adding special color pastes, it can also print various colored frosting patterns. It is also possible to first print a transparent, colored UV ink, then light-cure it and then overprint the frosting ink to obtain a colored frosting pattern. UV metal/glass frosting ink is specially developed for glass and mirror-like metal substrates. It has high hardness, excellent adhesion fastness and strong water resistance. In order to give the transparent frost pattern on glass a metallic shimmer, a layer of UV mirror silver ink is printed on the frost surface. When viewed from the reverse side of the glass or transparent plastic film, the frost has a metallic feel and the frost ink seems to be printed on mirror metal.
The mechanism of UV frosting is as follows: when UV frosting ink is exposed to ultraviolet light, two reactions occur. One is the main reaction, photochemical polymerization/crosslinking, which causes the ink to solidify and also produces a volume shrinkage. Because the resin in the formula has a high functional group, the frosting cured film is both hard and brittle. The shrinkage of the ink layer and the curing process are not synchronized and are also uneven. The result is inevitably stress concentration, which causes the cured film to crack, forming a pattern of cracks similar to those on an ice surface when it is hit, i.e. an ice pattern. The UV ice pattern is naturally formed and not man-made, and has the characteristics of natural beauty and a strong artistic feel. Another is a side reaction, the oxygen barrier effect caused by oxygen in the air, which means that oxygen hinders further curing of the ink and is detrimental to curing, especially on the surface of the ice ink layer in direct contact with the air, which is difficult to cure.
The formation of UV frosting ink can be divided into three stages: the generation of large cracks; the formation of small ice filaments; and the drying of the frosting ink layer. When the printed frosting ink enters the UV irradiation area, a white mist-like curing layer will slowly appear on the surface of the ink. The originally completely transparent coating becomes less transparent, and gradually forms a crisscross crackle pattern, just like many lightning trails in the sky. It generally takes 20 to 40 seconds of medium-intensity UV light to produce a large crack. As the large crack gradually deepens, the white mist on the surface of the ink layer gradually fades away, becoming transparent in some places and translucent in others. The ink layer becomes a transparent layer with many large cracks distributed throughout. In the blink of an eye, countless fine ice filaments appear at the edges of the large cracks, growing rapidly in the same direction until they meet the ice filaments on the opposite side. The ice filaments form in a very short time, generally 5 to 10 seconds. If you touch the surface of the ink at this time, it will feel slimy and not yet cured. The thickness and density of the ice silk determine the three-dimensional effect of the ice pattern. The denser and thinner the ice silk, the more obvious the reflective and refractive effects of the ice crystals, the stronger the three-dimensional effect, but the lower the transparency. The thicker the ice silk and the lower the density, the better the transparency of the ice ink layer. After the large cracks and small ice silk have formed, the ice ink layer needs to be quickly dried by exposing it to strong ultraviolet light, otherwise the beautiful ice pattern will become blurred due to oxygen inhibition. If you look closely at the UV frost pattern, especially with a high-powered magnifying glass, you will see that it is made up of many large and small cracks. Some of the cracks are long and wide, while others are short and thin (known as ice silk). The large cracks intersect and connect with each other, and the size of the frost pattern is determined by the area enclosed by the large cracks. The larger the area, the larger the frost pattern, and vice versa. Only by fully understanding the formation process and influencing factors of UV frost can frost decorations with a strong sense of three-dimensionality, high transparency, and suitable sizes be produced.
The properties of the substrate (color, transparency) also have a significant impact on the formation of the frost pattern. The darker the substrate color, the slower the frost pattern will set, and the larger the frost pattern will be. The lighter the color, the smaller the frost pattern will be. Other things being equal, the texture of the frost pattern can also be controlled by varying the base color.
To achieve a stable frost pattern, the temperature in the illuminated area must also be kept stable. This is because the formation of frost is clearly affected by temperature. The higher the temperature, the faster the oxygen in the ink layer dissolves, the more oxygen dissolves, the slower the curing, and the larger the frost. Therefore, when printing frost ink, production is normal in the summer, but when the weather cools, problems arise. The best solution is to keep the temperature in the printing room relatively stable.
The evenness of the printing of frosting ink not only affects the shade of the product’s color, but also determines the size of the frosting pattern. When printing frosting ink, a 200-260 mesh screen is generally used. A lower mesh count and thicker ink layer result in larger frosting patterns; conversely, smaller frosting patterns are achieved. The viscosity of the frosting ink is high, so the squeegee speed should be slowed down during screen printing to ensure an even ink layer. Otherwise, the finished product will not only have different shades of color, but also different frosting sizes.
When printing UV frosting ink, the ambient temperature should be kept as stable as possible. At high temperatures, the ink viscosity is low, bubbles disappear quickly, the printed ink layer is thin, and the frosting pattern formed after light exposure is small; at low temperatures, the ink viscosity is high, bubbles are likely to form during printing, the ink layer is thicker, and the pattern formed is larger. Therefore, fluctuations in the ambient temperature during printing will directly lead to changes in the size of the frosting pattern, which will affect the batch stability of the product. It is recommended that the printing environment temperature be controlled at 20-30℃.
The UV frosting light curing machine is much longer than an ordinary light curing machine. The standard four-lamp UV frosting light curing machine has a mesh belt/roller width of 2m, a lamp emitting area of 1.95m, the first three UV lamps have a power of 12kW, the last UV lamp has a power of 16kW, Total lamp power 52kW, machine width 2.2m, lamp box length 5m, total length 7-8m. Each UV lamp in the UV frosting light curing machine has a different function, and the lamp distance is adjustable. The first three lamps produce frosting, and the last one is used to cure the ink. The length of a normal three-lamp UV curing machine is usually only 2.5-3.5m.
UV ice flower curing machines require high temperature control and have many fans. Regardless of the season, the temperature inside the curing chamber must be kept between 35 and 55°C.
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