UV ink in the use of disc printing and curing two

2, UV lamp and UV irradiation machine

1 UV lamp

Compared with other printing methods, screen printing has a high film thickness, so it is recommended to use high-power (120W/cm or more). At the same time, please select the lighthouse of the closing type. The type of lamp, high-pressure mercury lamp, and metal halide lamp can be used. The company recommends using a metal halide lamp.

2 UV irradiation machine

There are air-cooled and water-cooled UV irradiators that can be used in any type of application. However, there are a lot of plastics in printed materials and the adaptability of overlapping printing. When using an air-cooled type, special cooling devices are recommended (COLD MIRROR and CUT FILTER). As the air-cooled irradiator irradiates, the temperature rises, resulting in poor overlay printing suitability (especially delamination) and the risk of thermal deformation of the plastic material.

3 lamp life

UV lamps have a certain service life, and the light year of the lamps also slowly declines. When UV light is used, the amount of light is often measured to enhance light management. 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.

3, factors that affect the curing

1 Material type and color

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

2 ink color (pigment nature)

In particular, pigments that absorb ultraviolet light will slow down the curing process, and the more they are contained, the stronger this tendency will be. Therefore, the concentration of UV-curing inks has a certain limit. 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 high concentration white and dark colors (black, blue, other) are used, care must be taken.

3 Photo-Curable Initiators Addition of a photo-curing initiator (curing accelerator JAR-2, JAR-8, JAR-15) is an effective method for improving the curability. However, excessive addition of photo-curing initiators will hinder curing. Please pay attention to the amount (less than 4%)

4 printing 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 to 12 μm. When the film thickness exceeds 15 μm, the phenomenon of poor adhesion due to poor curing occurs. Even if the varnish ink exceeds 100 μm or more, it has no problem in curability.

5 The lamp intensity W/cm2 and the integrated light quantity J/cm2 are the standards for judging the curing intensity and the total number of lamps. The intensity of the lamp is described in 2-1, determined by the output of the lamp and the shape of the lamp house. In addition, the data for accumulating the ultraviolet intensity and the irradiation time is the accumulated light amount. The amount of accumulated light varies depending on the number of lamps and the speed of the mesh belt and the irradiation time. The overall judgment of the curing property is determined by the amount of accumulated light, but the most important thing for the internal curing of the cured film in the direction of film thickness is ultraviolet light. When the UV intensity is low, increasing the irradiation time and increasing the amount of accumulated light does not improve the internal hardening of the printed film. In such a situation, please lower the height of the lamp or convert the lamp output high. solving issues.

6 Temperature at the time of irradiation and

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.

4, attention

1 Skin UV Irritation (P.1.1.)
Skin UV irritancy (P.1.1.) is the reference standard for the safety and health of UV inks.
●P. 1.1. Values; 0 to 1.29 (low); 2.0 to 2.9 (low to medium); 3.0 to 5.9 (moderate); 6.0 to 8.0 (intensity). UV inks by P. 1.1. A value of 1.9 or less constitutes a skin irritant. However, try not to touch the skin when using it. If it gets on the skin, rinse it with soapy water. Due to low skin irritation, sticking to the skin can cause inattention. However, some people may cause inflammation or rash due to prolonged exposure. Please note

2 When the printing ink is peeled from the interlayer, the lower layer of the ink is temporarily cured, which results in a decrease in adhesion to the upper layer ink. In this case, adjust the curing conditions.

3 Thermal deformation

Due to the heat of UV irradiation, the adhesive labels and films will be curled and deformed. In particular, dark inks such as black are more easily curled and deformed due to their ability to absorb heat. Please adjust the UV irradiation conditions and study the cooling device.

4 Mesh traces with Fu delivery machine

After passing through the UV irradiator, traces of the mesh of the reticle may be left on the printed surface. In particular, this phenomenon easily occurs on black ink and sheet materials. The reason is that the heating is uneven. Please change the thickness of the materials and mesh used in Fu's belt.

5 Tibetan safety

UV inks should be stored in a cool dark place. In the quality assurance period under this storage condition, the ink is usually within about one year after the ink is manufactured. When stored at a temperature of more than 30°C, gelation and thickening of the ink can easily occur. Once used ink, its storage stability will be reduced, do not let the ink in the container

6 Stirring

Before the UV ink is removed from the container, it must be stirred. Separation occurs due to a part of the ingredients and it is evenly stirred. The viscosity-increasing ink in storage can be restored to its original viscosity by stirring.

7 Mixing inks

In general, it cannot be mixed with other series of UV inks.

8 Product Safety Data Sheet

Items such as safety precautions are described in detail in the "Product Safety Data Sheet" of each product. When using it, you must refer to it. Compared with previous printing, UV ink printing has many complicated factors. UV irradiators often fail to achieve satisfactory printing results if the ink printing and printing conditions cannot be integrated.