Technology and application of the hottest UV inkje

Technology and application of UV inkjet inks (III)

3.4 colorants

colorants are preferably thermally stable and water-insoluble. Although it does not rule out the use of colorants soluble in diluents such as dyes, it is preferred to use colorants insoluble such as pigments, especially when light fastness is very important. The main problem of using organic pigments is to improve the dispersion stability of pigments and prevent nozzle blockage. At this time, it is better to include a dispersant in the composition to stabilize the dispersion of the insoluble colorant in the diluent

many kinds of pigments are suitable for coloring UV inks, but you still need to pay attention to your choice when using them. First of all, many pigments (4) are mainly used to promote the natural polymerization of vehicle in the dark. This natural polymerization does not take place immediately, but takes a period of time, so it will shorten the storage time of UV ink. In addition, different colors have different effects on the speed of absorption of UV light waves, which often affects the polymerization of UV ink. In other words, the drying speed of printing is affected, thus reducing the mechanical and chemical properties of the color film. Moreover, acry-lates used in the color carrier of UV ink is not a good wetting agent (wetyinca-cent), which often makes it difficult to grind the pigment and affects the smoothness and uniformity of the film in the future

3.5 additives

it includes dispersants, lubricants, thickeners, fillers, solid promoters, etc., which affect the curing speed, validity period and film thickness of the ink. But it can improve the printability of ink

4 current situation and development trend of UV inkjet inks

4.1 current situation of UV inkjet inks

so far, the sales of inkjet inks are dominated by the solvent based system that has been used for a long time. However, the market share of UV curing system is also increasing year by year, showing an upward trend. Based on the renewal of technology and the expansion of application fields, the growth of inkjet ink market is expected to exceed 17% annually by 2004. In the future, UV curing will experience a substantial growth in those traditional market areas

uv inkjet ink is mainly developed by cootsbrother PLC in the UK. The ink with strong chemical corrosion resistance and stain resistance produced by NCR company in the United States uses cationic initiator, and the monomer and oligomer also have cationic photo reactivity. According to the European patent, a UV curing ink for printing etch resistant circuit boards is also reported. Nazder ink company, nor Cote company and AkzoNobel ink company in the United States have also developed UV curable inkjet inks. The UV curing inkjet CTP technology of Japanese companies is also very mature

4.2 development trend of UV inkjet inks

a. development of new photoinitiators

most photoinitiators release photodegradation products with volatile and unpleasant odor. New photoinitiators have been put into the market, such as esacure kt046 of Lamberti company, Esacure does not have any damage and parameter error lool and amine co initiators, as well as esacure kt550 produced by odorless and volatile matter

B. water based UV curing system

water based UV ink combines the advantages of UV and water-based ink: it maintains the printing and drying speed of UV ink; Viscosity is lower than UV ink; Thinner than the traditional UV ink layer; Compared with the commonly used UV ink, the smell is small, because water reduces the acrylic vinegar a: please first confirm whether the "test piece" clamping is the unique acrylic smell of the solid monomer, and at the same time, the final print will not bring the user a special "UV" smell; If necessary, the adjustment of ink can be completed with the help of water, without the need for additives next to the printer; Waterborne UV curing inks can adhere to special surfaces, such as gloss or matt surfaces without vinyl coating

the best substrates for water-based UV inks are coated paper and paperboard. In Europe, water-based UV ink is widely used to print line patterns on corrugated board. However, it is difficult to prove that water-based UV ink for printing line patterns is superior to ordinary UV ink. Thin non coated paper is not suitable for water-based UV ink, because this paper will absorb water and wrinkle or curl. The ink layer of water-based UV ink has a finish similar to that of solvent based ink. This kind of ink is mainly used for four-color printing, point of purchase advertising, traffic trunk advertising and light boxes

however, there are still some technical problems to be considered in terms of UV curing inks of aqueous systems:

(1) ordinary reactive monomers and oligomers used in 100% UV systems are insoluble in water

(2) traditional photoinitiators have poor compatibility with water because they are solid or difficult to disperse

(3) for impermeable substrates, the removal of water is particularly important

the method of ethane oxidation with chemical structure can improve the water solubility of various AA reactants. When these acrylic acid solutions are stable in the varnish, some components can also exist stably in the pigment system. Water dispersion of acrylic acid vinegar is another technical method for preparing low viscosity ink

sartomer has a series of photoinitiators with good ecological effects, such as esacure kip/em, esacure dp250 and the new, semi commercial lfc1708. These products are stable aqueous lotion, which are easily miscible in aqueous UV inks. The preparation of this lotion requires a grinding process to reduce the particle size of the lotion to the appropriate and allowable range of inkjet ink. All these products cover the UV absorption range, which can range from 250nm to 420nm. Saiangel company in the United States also uses aqueous UV curing method to prepare ink

source: China printing chemicals