Direct Thermal

How it works:

The production of a thermal paper begins with an uncoated base paper, like Vellum, which is transformed into a direct thermal paper with the application of a chemical coating. The first chemical layer is the under layer, prevents the heat generated by the thermal head from dissipating through the paper. This ensures a better resolution when printing at low energy.



The second chemical layer is the thermal layer, it contains a dye and a developer. When exposed to the 250° C emitted by the thermal head, the thermal layer melts, bringing the dye into contact with the developer and forming the thermal image. But there are some important things to be consider, the thermal layer is quite fragile and can be broken through exposure to oil, plasticizers or water and it cause fading of printed image. To prevent this happened, a barrier coatings are available to add an element of protection.

ECO    
No topcoat  
No resistance to plasticizers,oil or water  
No scratch resistance  
Recommended for short life in a safe environment  
     
SFMI  
Barrier-coated on topside  
High bar-code scratch resistance  
Good image stability  
Recommended for logistic labels  
     
TOP  
Barrier-coated on top and reverse side  
Smudgeproof  
Barrier-coated on top and reverse side  
Good scratch resistance  
Well protected against chemical and mechanical stress and high humidity  


Direct Thermal and pre-printed Inks
Printing a thermal paper with the ink is no more complicated than printing on standard paper. Some consideration must be given to the ink in order to avoid damaging the thermal printer or reducing the print quality. The use of a special range of inks is recommended for direct thermal papers in order to avoid trouble.

Heat resistance - The ink should be able to tolerate the 250 °C generated by the thermal print head. In addition to lowering the image quality, molten ink residue on the print head prevents proper cooling and leads to burnout.

Abrasive particles - Titanium dioxide is a very abrasive pigment. It is chiefly used as a white colorant in water-based flexo inks. Creating lighter colour shades by adding a white colorant is not recommended as it has an adverse effect on the service life of the thermal head.

Ink adhesion on top-coated paper - Thermal TOP papers are coated with a non-absorbent topcoat. In order to achieve optimal ink anchorage, special inks must be used.

Metallic colours - Metallic pigments are quite abrasive. The use of metallic inks on direct thermal paper is not recommended as it reduces the service life of the print head.

Amine ratio and Thermal Eco - If the amine ratio in the ink is too high, the thermal layer in Thermal ECO will react and turn grey, affecting the shade of the pre-printed image. Check that the ink is recommended for use with direct thermal ECO papers.

Storage Instructions
Recommends that the labelstock is stored in room temperature ( +20 °C ) at a maximum relative humidity of 50 %. Labelstock should be kept in its original packaging and protected from light. Damp or hot conditions should be avoided.

The shelf life is calculated from the date of the labelstock's manufacture and is based on the adhesive's ability to maintain optimal labelling properties during storage.



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