Tampa^® Pur TPU.

The ink should be stirred homogeneously before printing and if necessary during production. To protect the ink in opened containers against excessive drying, it can be carefully covered with a layer of thinner which can then be later stirred into the ink prior to printing.

Prior to printing, it is a must to add Hardener in the correct quantity. The ratio is as follows:

When using hardener, the processing and curing temperature must not be lower than 15°C as irreversible damage can occur. Please also avoid high humidity for several hours after printing as the hardener is sensitive to humidity.

Pot life

The ink/hardener mixture is chemically reactive and must be processed within 7-8 h (H 1) or 3-4 h (H 2), referred to 20-25 °C and 45-60 % RH. Higher temperatures reduce the pot life. If the mentioned times are exceeded, the ink's adhesion and resistance may be reduced even if the ink still seems processable. With the use of HT 1, there is no pot life to consider since this hardener is only activated by a baking process (30 min/150° C).

Parallel to physical drying (i. e. the evaporation of the solvents used), the actual hardening of the ink film is caused by the chemical cross-linking reaction between ink and hardener.

The following values concerning progressive cross-linking (hardening) of the ink film can be assumed:

Chemical cross-linking can be accelerated by higher temperatures. The times mentioned vary according to substrate, depth of cliché, drying conditions, and the auxiliaries used.For quick printing sequences, we recommend forced air drying (about 200°C for 2-3 sec) of the surface after each colour.
For multiple colour printing we point out that the previous printed ink film should not be entirely cured before the consecutive ink film is printed on top of it. By drying at room temperature, the consecutive print should be carried out within 48 h after the previous print when Hardener H 1 is used and 8 h after the previous print when Hardener H 2 is used.

Clichés
All commercially available clichés made of ceramic, photopolymer, thin steel, and chemically hardened steel (10mm) can be used. The recommended cliché depth is 20-24 µm.

Printing pads
As per our experience, all common printing pads consisting of materials cross-linked by condensation or addition can be used. 

Printing machines
Tampa^®Pur TPU is suitable for closed ink cup systems, as well as for open ink wells. Depending on type and usage of the machine, it is to accordingly adjust type and amount of the thinner used.