UV ink consisting essentially of: a prepolymer, a reactive diluent, a photoinitiator, a pigment, and other additives. A prepolymer comprising: epoxy acrylate, polyester acrylate, urethane acrylate, modified acrylate. Adjust viscosity reactive diluents have, fixed rate and fixed ink film after the performance of the role. Divided into multifunctional and monofunctional. Principle UV ink curing radical is formed after photoinitiator absorbs radiation, causing the prepolymer and reactive diluent, a crosslinking reaction occurs to form a polymer network structure, so that the liquid quickly become solid.
UV inks current common high-pressure mercury lamp light source, its strongest wavelength of 365nm. Years of application structure shows that UV curing technology is a highly efficient, energy saving, economical, wide applicability and environmentally friendly technologies. But there are also some drawbacks: 1, limited UV mercury lamp life. 2, energy UV mercury lamp is large, efficient use of energy is not high, the input energy only about 20 percent of the energy generated ultraviolet light, while 20% of 40% of visible energy is heat, not suited to heat-sensitive materials. 3, although the mercury UV resistance for solvent-based inks, there is no VOC emissions and are environmentally friendly and environment-friendly features. But there are some hidden pollution. Such as high pressure, high temperature and intense radiation of a mercury lamp, it is easy to make the surrounding oxygen molecules react to generate ozone. Ozone not only have an adverse effect on the atmosphere, but also on health also have a greater impact.
Relatively speaking, LEDUV light has the following advantages:
1, cold light, no heat radiation, the illuminated surface of the object temperature is low. Such a characteristic sense of time in a liquid ink exposing welding process does not make the film sheet deformation, reducing the degree of distortion of the image transfer, to better ensure the consistency of maps and images. Thermal damage can solve the problem long-standing LCD production of optical communications, especially for liquid crystal Edge, film printing and other requirements applicable to small temperature rise of the occasion. Heat a small, solve the mercury inkjet equipment heat, staff unbearable problem, and the LED light source is a high-purity single-band ultraviolet light, almost no infrared output, it is a cold light source, the workpiece will not heat deformation.
2, high efficiency. LED light energy is highly concentrated in certain segments has an effective UV curing effect, the actual use of effects and light intensity of the curing effect 1000-2000mw / cm of conventional high-pressure mercury lamp UV light comparable. Thereby shorten a curing time. Traditional mercury light brightness looks high, but high in calories, because its spectrum is very wide, that really effective action of UV curing is only part of the energy segment, a considerable part of the visible light and infrared segment loss in the Spectrum degree (causing heat generation) serious eye damage and operation is easy to workpiece thermal deformation.
3, long life. LED lamp life is more than 10 times that of traditional mercury lamp, and the number of switching life without influence.
4, reaction (switch) fast time. LED lights do not need to warm up immediately after printing can boot, productivity can be improved.
5, safe. LED light no UVC rays, no ozone release are not damaged.
6, high stability. Print quality UV inkjet printers with UV drying and curing process is closely related to the stability of LED lights so that the output power is predictable, stable, and therefore the same printing results are predictable and stable. LED let the ink deep curing, LED lamps emit light wavelength is 395nm, allowing the ink deep curing, so printing surface is dry but the underlying quit will not happen. On a variety of print media has a very strong adhesion and anti scratch resistance.
7, low energy consumption. LED lights very low power, equivalent to only 10% -20% UV mercury lamp.
LED curing light between superiority, LED curable inks developed into today's UV ink development direction of the industry. Development of LED-curable inks, the first thing to consider is the relative nature of the photoinitiator, a factor that must be considered when selecting a photoinitiator is light emission spectrum agents initiator absorption spectrum matches the light source.
Second, we must consider is the pigment with nature. With respect to the emission wavelength of the LED, since the substance contained in the ink with UV light initiator such pigment absorption wavelength coincides agent, as compared with the transparent pigment-free varnish, etc., curing properties become poor. Compared with the conventional LED curing type UV ink must be selected for a particular wavelength of UV light used for the purposes of good penetration (absorbent small) pigment.
In addition, the activity of the prepolymer and monomer selection is important.
Currently, LED curing device gradually move toward the market, so LEDUV curable ink will gradually replace traditional UV-curable inks. Development and improvement of LED-curable inks will be the focus of future research.