UV inkjet printing technology application (5)

5 UV ink technology

1 UV inkjet ink classification and material

Acrylic UV inks are shown in Table 3.

The products currently on the market do not contain 100% solid-state solvents. Instead, non-aqueous inks composed only of acrylic reactive components are used. The 100% solid state UV ink has the following features.

1 Fast curing, so the printing speed is fast.

2 There are a large number of printed materials including non-absorbable materials, basically no printability like inkjet paper, and original materials are available.

3 Because organic solvents such as oil-based pigment inks are not used, there is no residue of volatile organic solvents, and there is no need to worry about the safety of the printing shop and environmental pollution.

4 Because there is no solvent, there will be no problem of fixation of residual ink on the print head, making daily printer maintenance easy.
5 Since the ink does not undergo component changes during storage, it is advantageous in terms of operability and reliability.
6 The cured ink has good adhesiveness, chemical resistance, hardness, and abrasion resistance.

7 can get high gloss ink film.

8 Because the surface after printing is dry quickly, it can immediately enter the latter process.

2 acrylic UV ink material

The acrylic monomers and oligomers used in UV inks are reviewed in the manufacturer's catalog and are not repeated here. Low viscosity compounds are used as ink binders in these products.
According to the design of the ink, there is an optimum range of characteristics depending on the respective print head, and at the same time, a small amount of organic solvent is sometimes blended from the viewpoint of miscibility. Sometimes, a gel or solid ink is formed from the viewpoint of the physical properties of the cured material, that is, a liquid or waxy ink having a high viscosity is formed at a normal temperature, and the temperature around the print head is adjusted to increase, and the ink is moderately reduced when ejected. Viscosity method.

In response to the problems of UVEB material oligomers in the past, physical properties were adjusted. For inkjet materials, the requirements are low viscosity, difficult to vaporize, difficult to spatter, and superior solidification properties. It is safer to develop more than itself. compound of. As a method that is both multi-functional and reduces viscosity, a spherical radial driden type technology has been developed, which is an interesting idea for the ink jet process. On the other hand, a print head that meets the characteristics of the ink should also be designed.

3) Photoinitiator

The photopolymerization initiator was selected based on the quantum efficiency, the polymerization efficiency, and the practical requirements of the cured ink film. With only a small amount, the efficiency is improved, and it is hoped that a compound that does not affect the ink film will be selected. New materials are being developed with the device. Currently, in accordance with market demand, high-performance and highly stable compounds are being developed as initiators.

4) Coloring material

UV inkjet inks can achieve the desired composition based on the pigment to resin binding ratio. A sufficient amount of the resin can suppress light scattering in the pigment ink layer, that is, the smoothness of the ink film is improved by curing. Inkjet pigments are dispersed in an ultra-fine manner, so the color is quite good.

The colorant is the component that best reflects the printing use. The type is formulated depending on the use. Where pigments are used, the dispersion process is very important. Basically divided into 1 in the organic solvent dispersion and single system conversion method; 2 in the monomer used in the method of dispersion. When water-based inks are used, the technique of water-dispersing for ink-jet dispersion has already been established, and it is fully applicable.

Dispersion stability For any ink form, the optimum design of the corresponding linking material is needed because the inkjet printing is bright and can give a rich color reproduction, which has a great advantage compared to the original printing. .

5) Oxygen-based UV ink

Epoxy polymerization systems made of photodegradable cations are suitable for UV ink-jet printing, but they are theoretically possible, but they have not yet been introduced as products. Classes containing vinyl ether and oxycyclobutane resins are currently being studied. The use of the resin is not only advantageous to the image, but also to the use of precision coating or analog coating.