The trend of ink curing and drying (3)

The characteristics of microwave lamps are:

1Adjustable radiant light intensity with wavelength distribution characteristics, select the best radiation wavelength, so that the ink achieves the desired curing effect.

2 Because the lamp tube has no electrode, the lifetime when the power density is 300W/cm can reach 5000 hours, and the switch does not affect the lamp life.

3 Because the microwave source is easy to control, the microwave lamp can be started frequently and frequently, but the microwave also has a standby state (maintaining the working state), and it can only be started quickly in this state. This function is suitable for the use of optical discs and stickers printers, because screen printing and sticker printing are mostly intermittent printing.

4 The UV curing section of microwave lamps is rich in spectrum and less in infrared, so the microwave radiation temperature is low.

5 Because the microwave lamp has no electrode, it is very convenient to replace the lamp, and no wiring is required.

6 Because there is no electrode release, both ends of the lamp will never be black.

7 Due to the limitation of microwave transmission, the maximum length of the microwave lamp is 6 inches. Placing the lamp connection increases the curing width. Since the lamp gap is small, the joint will not affect the curing effect.

8 The price of microwave lamps is relatively high. A set of 6-inch curing devices is about 50,000 yuan. At present, the domestic market is mainly used for the curing of UV inks compatible with inkjet printers, cables, tubes, and flexible packaging.

9 Microwave Lamps The luminescent materials are the same as ordinary UV lamps. The wavelength distribution of radiation is the same, so no special ink is required.

(4) UV lamp reflector design. The scientific choice of reflective materials and rational design of the reflector structure can double the effect of curing and save energy. The aluminum crystal formed by oxidation of pure aluminum has 90% UV light reflectance, while the non-oxidized aluminum plate reflects UV light less than 60%; the stainless steel has less than 60% UV light reflectance; and the semiconductor coating reflects UV light. The rate is 94%, but the cost is higher. At the same time, infrared and visible light can be transmitted through the coating to reach the surface of the reflector, and after being cooled by the cooling device.

The development trend of the reflector design is the change of the opening and height, that is, the sectional area becomes smaller to shorten the reflection light path and reduce the loss of light intensity due to the long optical path length. In addition, the reflector plate at the top of the reflector changes the design of the original top opening ventilation hole, so that the radiant energy at the top of the lamp tube is reflected to the paper surface, as shown in FIG. 4 . Due to the small cross-sectional area of ​​the lampshade and the distance from the lamp wall to the reflective surface, the temperature of the reflector is too high, and the top reflector will block the wind and affect the heat dissipation of the lampshade. The solution is to cool the lamp shade or increase the amount of cooling air, and rationally design the cooling air path.

Advanced curing equipment

1. Microwave UV curing equipment

The feature of this equipment is that, due to the need of microwave transmission channels, the lamps are large in size and should not be installed in the sheet-fed offset printing machine. Generally, they are printed with the unit-type flexographic printing machine, gravure printing machine, forms, and stickers. The use of the machine, CD-ROM and inkjet printing system is also suitable for the equipment, but due to the high price, the printing plant is rarely used.

2. High power density UV curing equipment

The power density of electrode UV lamps produced in Japan can reach 240-300 W/cm, which can be used in table printers for screen printing to cover the curing of UV-silver pastes; the power density of UV lamps used in American Andy flexo printers Has reached 400W/cm, curing speed 150m/min; Fusion's microwave lamp power density of 400W/cm.

The high power density UV curing device not only accelerates the curing speed, but also facilitates the complete curing of the UV ink layer on the thick UV ink layer and rough paper. In addition, increasing the power density of the UV lamp can reduce the photosensitivity of the UV ink and reduce the content of the photoinitiator, thereby improving the stability and sensitivity of the UV ink, facilitating storage and transportation, and at the same time reducing the price.

3. Water-cooled UV curing system

Due to the development of the structural design concept of printing equipment, the structure of the printing press is more compact and beautiful, and the large UV curing air cooling channels can no longer meet the requirements. Therefore, such printers generally use water-cooled UV curing equipment. For example, the UV drying systems configured for imported multicolor offset presses are water-cooled, and the satellite-type adhesive printing machines are also equipped with water-cooled UV systems.

I often found in the printing plant, there are many unreasonable phenomena in the ink drying, curing process, resulting in greater waste of electrical energy. For example, some curing equipment is not scientific because of its unscientific design, but its efficiency is very low, although it is cheap. For a glazing machine with a speed of less than 3,000 sheets/hour, three 10kW UV lamps are used. If reasonable, use only 1 12kW lamp can be. For another example, the power of the curing system before and after the unit-type printing press is unreasonable, causing the printing speed to go up. And many manufacturers only consider the cost of equipment, ignoring the expenses of electricity. In view of the above problems, it is recommended that the printing factory should consider various aspects when selecting the curing equipment.

Source: China Ink Network