Screen printing UV ink use and precautions (2)

Second, UV lamp and UV irradiation machine

1. UV lamp

Compared with other printing methods, the ink thickness of the screen printing is thick, so it is recommended to use high-power lamps (above 120 W/cra). At the same time, select the bundled lamp. The type of lamp, high-pressure mercury lamp, or metal halide lamp can all make Chuan, and it is recommended to use a metal halide lamp.

2. UV irradiation machine

There are air-cooled and water-cooled UV-irradiation machines, which can be used in any type. However, when considering the problems of more plastics in printed materials and the suitability of overprinting, air-cooled air-cooled models are used. It is recommended to use a special cooling device. Because the temperature of air-cooled irradiation rises during the eruption, overprintability and thermal deformation of plastic materials are caused by overprinting.

3. Lamp life

UV lamps have a certain service life, and the luminous power of the lamps has also slowly declined. The UV light quantity meter is commonly used in the Qing Dynasty to enhance the management of UV lamps. Before the service life limit of the UV lamp arrives, the curability of the ink will be reduced. Therefore, exchange the UV lamp as soon as possible.

Third, the factors that affect the curing

1. Material type and color

Some types of colored materials have the property of being particularly UV-absorbing, and curing of these materials will slow down. In addition, materials of the same kind also differ in their curability due to different grades.

2. Ink color

UV-absorbing pigments, in particular, have a slower cure, and the more they are contained, the stronger this tendency is. Therefore, there is a limit to the concentration of the UV curable ink. In particular, various primary color inks do not have a curing problem when they are toned, but the color inks have a problem of poor curing. Especially when using high concentrations of white and dark (black, blue or other), pay full attention.

3. Photo-curing initiator

The addition of a photo-curing initiator is an effective method for improving the curability, but the excessive addition of a photo-curing initiator may rather inhibit the curing. Please pay attention to the amount of addition, the general added amount is controlled within 4%.

4. Print film thickness

The thinner the printed film, the better the curing property. The general colored ink can obtain sufficient curing performance in a film thickness range of 10-12 μm. When the film thickness exceeds 15 μm or more, poor adhesion due to poor curing occurs. Even if the varnish ink has a thickness of more than 100/xm, it will have no problem in curability.
5. Lamp intensity and integral light quantity

In order to judge the hardening of the standard lamp intensity and light intensity, the intensity of the lamp and the power of the lamp and the shape of the lamp house. The data of the integrated ultraviolet intensity and the irradiation time is the integrated light amount. The amount of integrated light varies depending on the nature of the lamp and the exposure time. The overall judgment of hardening is determined by the amount of integrated light.

6. Irradiation temperature

The ambient temperature during UV irradiation has a great influence on the curing of the UV ink. The higher the temperature, the better the curability. Therefore, if the preheating is performed, the curability of the ink will be enhanced and the adhesion will be better.

Fourth, the use of UV screen printing ink precautions

1. Skin UV Irritating

Skin UV irritability is a reference standard for the safety and health of UV inks. However, try not to touch the skin when using it. If it touches the skin, rinse it with soapy water. Because of its low irritation to the skin, it does not attract attention on the skin. However, some people may cause inflammation or rash due to prolonged exposure.


Source: 21st Century Fine Chemicals Network

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