Analysis of Technical Features Applied in UV Printing Process

In general, the types of technologies that UV printing will apply to are briefly described below:

1.UV light source equipment

Including lamps, reflectors, energy control devices, temperature control devices (or cooling devices).

(1) Tube

The most commonly used type of lamp used for UV light sources is mercury-filled mercury lamps (Mercury Lamps). Sometimes, other metals are added, such as Gallium. In addition metal halide lamps, and quartz lamps (quartzlamp) are also common types. At present, many rely on imports. The electromagnetic wavelength emitted by UV lamps must be between 200 and 400 nm.

(2) Reflector

The main function of the reflector is to reflect the UV electromagnetic waves back to increase the efficiency of the UV light source (UV Tech Publications, 1991). Another important function is to maintain the operating temperature of the lamp. The surface of the reflector is usually made of aluminum and the reflectance requirement usually needs up to 90%.

There are two basic types of reflectors, one is the focusing type and the other is the defocusing type. Along with the development of the manufacturer, there are other extension types.

(3) Energy Control Device

The main energy supply of this device is to control the UV energy emitted by the UV lamp to be stable, so as to maintain the efficiency and stability of the hardening, in order to meet the needs of different printing speeds. There are electronic designs and there are also microcomputer controls.

2. Cooling device

Since the UV lamp emits IR (infrared wave) when it emits UV electromagnetic waves, the UV equipment will operate at a high temperature (for example, the temperature of the quartz lamp can reach 600~800°C), which will not only shorten the life of the equipment However, the importance of the cooling device is evident in the fact that prints are also prone to stretching.

3. Ink supply system

Since UV inks have higher viscosity, higher friction, and damage to the components of the printing press (including blankets, ink rollers, etc.) than conventional lithographic inks, the ink in the ink tank should be treated in addition to printing. Should continue to be stirred, the ink roller and blanket used in the ink supply system should be designed for UV printing. In order to maintain the stability of the UV ink, so as not to affect the viscosity of the ink, the temperature control device of the ink roller is also an important device.

4. Heat dissipation and exhaust device

The main function is to remove excessive heat from the inside of the machine and eliminate the ozone generated when the ink cures and polymerizes. Usually consists of an exhaust motor and an exhaust pipe.

5. Printing ink

Whether the quality of the ink is good or not is the most critical factor that directly affects the UV printing. In addition to affecting the traditional quality factors such as color performance and color gamut, the printability of printing ink directly affects the adhesion, strength, and anti-friction force of printed materials after printing is completed. Photoinitators and polymer monomers and their properties are key basic materials.

To control the adhesion of the UV ink, when the wet UV ink is in contact with the object to be printed, the surface tension of the object to be printed (unit: dynes/cm) must be higher than the surface tension of the ink (Schilstra, 1997) to produce Good ink adhesion, so controlling the surface tension of the ink and the printed material is an important technology for UV printing.

6.UV energy measuring equipment

In UV printing, because the UV lamp aging, power supply, printer speed and other factors, need to control the UV energy to remain stable, so the measurement of UV energy technology has become a very important part.