UV ink test and quality control (below)

Key equipment

Any well-stocked laboratory has a sufficient number of equipment. Each ink manufacturer has its own recommended equipment for UV ink testing.

Webster said, "The most critical test tools for UV inks are UV lamps and scraper manual hand-scrapers. UV curing systems with variable-speed tables are critical. Calibration and testing of the UV lamp's regularity is important. Plate speed calibration and wavelength output intensity test of UV lamp itself.Because UV flexo ink is slightly more viscous than traditional inks, when proofreading in the laboratory, a high quality scraping knife is needed to manually scrape the sampler to equalize and color. Strong inks are applied to the substrate. Advanced rheology technology, such as controlled stress steady-state viscosity measurement, provides detailed information on the performance of UV flexographic inks compared to simple viscosity cup measurements."

Radiometers are important for adjusting UV lamp speeds to simulate printer conditions. In addition, it is also important to use the same type of lamp as in the customer's factory.

INX recommends a UV curing unit, viscometer, and sample scraping device, each of which is designed to handle the higher viscosity of UV inks.

Flint Ink recommends a variety of equipment, including ink gauges, ink curing analyzer (ICA), Kershaw/Lithotronic, stick gauge, gloss meter, spectrophotometer, UV/VIS spectrophotometer, Sutherland Rub Tester, UV Laboratory curing unit, electron beam laboratory curing unit, rheometer and Prufbau.

Lazure recommends that laboratories use laminar viscometers or rotational viscometers, ink meters, spectrophotometers, densitometers, fineness meters, laboratory curing units, shaving equipment, and water balance equipment.

Special challenges

UV ink manufacturers and corresponding end-users also need to meet certain field requirements. For example, the shelf life of UV inks is a factor that manufacturers need to consider. The shelf stability of UV inks is usually worse than that of conventional inks, so more attention must be paid to this. The decisive factor can be the storage environment temperature and the type of packaging used. The shelf life can also be shortened due to the incorrect selection of raw materials and their interaction with other materials in the ink. Another factor that can play a destructive role is the production process used to produce the ink.

The standardized inspection process helps the development of the ink industry. Developing an appropriate test procedure for UV flexo inks is an industry-wide challenge. This is due to the need to consider comprehensively the complexity of the curing device, the diversity of the curing lamp structure, the lamp life, and the equipment maintenance cycle. Any change in any of these parameters will affect the amount of energy needed to cure the UV ink, which will affect the performance of the final product.

UV ink testing and quality control are relatively straightforward. For other inks, the use of properly calibrated appropriate test equipment is critical. The challenge here is how to adjust the error between the customer's requirements and the final product performance so that the performance on the press and the customer's end-use needs can be truly achieved while achieving maximum productivity and consistency.

Source: China Coating Network