UV Printing

The curing of printing inks, inkjet inks and coatings using UV irradiation is an efficient technology that can be used to process a wide range of substrates and achieve a high degree of finishing.

We can determine the optimum lamp settings for you and identify when cleaning or early maintenance of the lamp modules is necessary. The goal is not only to ensure reliable curing of the inks and varnishes but also to optimise energy consumption. With regular testing, the condition of the UV lamps can be continuously monitored and a decline in performance due to aging or contamination can be recognised quickly.

The sliding friction coefficient of the ink surface can be used to estimate the degree of curing of printing inks and varnishes. The surface becomes smoother the drier/more cured the ink is. This relationship is well-known with UV inks and varnishes and is used by the UV Cure Check measuring device which is offered by PITSID GmbH to determine the degree of curing.

The degree of curing can also be determined with an FTIR spectrometer. The conversion of the acrylate double bonds is measured using a band in the IR spectrum. In addition, the interaction of the UV lamp and printing ink can be evaluated with regard to curing. The efficiency of the curing process can be determined over the complete printing format and the necessary radiation dosage for a speed-dependent power control of the lamp can be ascertained.

A dosage measurement is required to assess the irradiation amount that actually hits the printed product and triggers the curing process. The commercially available measuring strips for measuring the dosage of mercury vapour lamps cannot be used for UV LEDs, as they only absorb in the range from 200 to 350 nm. The spectrum emitted by LEDs with the wavelengths of 365 / 375 / 385 / 395 nm cannot be recorded with these strips. For this reason, SID has developed new measuring strips specifically for this range.

The strips are fixed on a sheet in the feeder pile and evaluated after passing through the printing press to assess the colour change caused by the UV irradiation. This approach offers several advantages, as the irradiation reaching the print under real production conditions can be measured. Fluctuations due to substrate distortions or shadowing caused by moving machine parts can be detected in this way. This allows us to check only whether the level of UV irradiation is sufficient to cure the inks and coatings used. Detailed analyses can also be carried out on the homogeneity of the UV irradiation over the entire sheet surface and on the influence of different printing conditions such as substrates and printing speeds.