The image made by a Thermal Transfer Printer appears when a substrate and the ink from a thermal transfer ribbon contact a heated print-head. As a result, heat from the print-head melts the ink on the ribbon and releases (transfers) the ink directly onto the substrate. These printers use a special ribbon, often abbreviated to TTR.
Thermal Transfer Ribbons are mostly used for printing variable information. This particularly concerns information for identification, such as barcodes, batch codes and expiry dates. Printing with this method is preferred when a durable result is needed, for example against heat, chemicals and abrasion. In addition, It works well in making highly durable non-variable information, such as warning signs.
Printing with Thermal Transfer Ribbons is a proven technique to deliver durable variable codes, such as barcodes, that always read or scan. It produces dense, high-resolution images in colour or black-and-white. Additionally, it can be used on a wide variety of substrates. Images made with these ribbons are highly resistant to chemicals and extremely durable. The printers work at high speeds and require little maintenance.
The ink used in the Thermal Transfer process can be made with wax, resin, or wax/resin. As a result, the different types of ribbons have a different print sensitivity. This means they transfer ink at different temperatures of the printhead. The requirements of the application determine which ink is needed.
Two types of printers are used: flat-head and near-edge.
In a Wax ribbon, the pigments of the ink are captured in wax. The wax is quite soft and therefore transfers at relatively low temperatures. It also fills up unevenness in the surface of the printed material/substrate. Therefore, wax ribbons are the standard for printing on (un)coated paper and other materials with a rougher surface. Due to the ability to fill up uneven surfaces, these ribbons deliver a high optical density print for scannable barcodes and other variable information.
In a Wax/resin ribbon, the ink is captured in a mix of soft wax and hard resin. Wax/resin ribbons make prints that are more resistant to scratching, rubbing and chemicals. These ribbons need a higher temperature for the ink to be transferred onto the substrate. Wax/Resin ribbons are suitable for both print & apply and in-line flexible packaging applications. For in-line printing at high speed, wax/resin ribbons are the obvious choice.
In a Resin ribbon, the ink is captured in resin. Resins are hard and provide the highest possible resistance against severe abrasion, harsh chemicals or other severe circumstances. Resin ribbons require a higher transfer temperature setting of the printer over wax or wax/resin ribbons. Typical applications where resins are used are labelling of chemicals, marking of laboratory samples and challenging circumstances in, for example. the automotive and electronic industry.
Thermal Transfer Printing is a method where heat is used to transfer ink from a ribbon onto a substrate. For a good thermal transfer print, the right amount of heat needs to be applied to the ribbon. When the heat settings are incorrect, the print might not be good. For instance, when the temperature is too high, the ribbon might break. That’s what we call ribbon breakage. Different types of ribbons require different amounts of heat. This is what we call the print sensitivity of a ribbon.
Flat-head printers have a traditional printhead that can generally provide image resolutions between 200 and 600 dots per inch (DPI), in some cases, this can go up to 1200 DPI. Their ribbons are married with labels for a small distance to the peel point after passing the heating element. These models will generally print at speeds up to 12 inches per second (IPS). Some printers are able to print up to 20 IPS when the right ribbon is selected.
In contrast, near-edge printers with their floating printheads will run more than twice as fast. Speeds over 26 IPS are the norm where 55 IPS is also reached by certain printer-ribbon combinations. Ribbons for near-edge printers are married with labels only for an instant prior to the peel point, requiring a special formulation engineered for quick release of ink from the base PET film. A floating printhead means not having to make adjustments for various media thicknesses. In addition, the image resolution for these printers is lower at between 200 to 300 DPI.
It is important to realize that a proper combination ribbon and substrate is needed for the optimal print result. The material that is printed influences how well the ink from the ribbon is transferred to the substrate and fixed to the surface. It is, therefore, necessary to consider material characteristics of the substrate, including the smoothness of the surface, when selecting a ribbon for a certain application. DNP is constantly testing new ribbon-substrate combinations. With our ribbon finder you can easily see which ribbons work well with a certain substrate.
It is important to realize that the correct use of a quality ribbon will extend the life of the most valuable component of your printer: the printhead. Ribbons can play a role in the wear and tear on printheads. In essence, there are three causes for this: too much heat, printhead in direct contact with a rough substrate and pollution. When a printhead is not performing correctly, white lines and dots will come out on the print. The quality of the print will deteriorate and the scannability of barcodes becomes problematic. To protect your Thermal Transfer Printhead, make sure to:
Near-edge and flat-head printers require different ribbons. In almost all cases a ribbon is uniquely designed for either a flat-head or a near-edge printer. Some specific ribbons are suitable for both systems. The main difference between the two types of ribbons has to do with the release layer. Due to the short exposure time to the printhead, a near-edge ribbon needs to release the ink much faster and is therefore formulated differently. This animation is specially made to explain the difference. You can use our Thermal Transfer Ribbon finder to find the perfect ribbon for your flat-head or near-edge printer.
Some applications and circumstances require a print that withstands extreme exposures, such as heat and chemicals. For these prints, a highly resistant ribbon is needed and we often get the question “What is the best Thermal Transfer Ribbon in your assortment?”. For heat and chemical resistance, the answer is R550. Prints from this resin are resistant for continuous temperatures up to 300°C and are superior in chemical resistance. The information printed with R550 is highly resistant to scratching and abrasion. R550 is an evolution of R510, which is another highly resistant ribbon in our assortment. R510 is approved for many applications and has numerous certifications to be compliant with specific industry requirements. Contact us if you want to know which of the ribbons works best for your specific situation.
Thermal Transfer Overprint (TTO) is a method where heat is used to transfer ink from a Thermal Transfer Ribbon onto a flexible substrate like food, beverage, and medication packaging. This technique is designed for use on flexible packaging and is used for the printing of barcodes and variable information such as best-by dates and serial numbers. The challenge of printing on flexible packaging on a high-speed production line is to guarantee high-quality printing with compliant variable data on each and every item. In-line printing is done at high speeds of 20 IPS and therefore requires specific Thermal Transfer Ribbons. This animation explains more about TTO printing and the selection of the right ribbon.
Depending on the printer it is intended for, the ink on a Thermal Transfer Ribbon can be coated on different sides of the ribbon. When a ribbon is wound “ink side out” it means that the ink is coated on the side of the foil that is exposed to the outside. When a ribbon is wound “ink side in”, the ink is coated on the inner part of the foil, meaning that the ink is covered by the foil when wound on the roll. The ink side of a DNP ribbon is indicated on the label of the roll and the box. When not sure, a so-called “tape-test” can help: stick a piece of adhesive tape on each side of the ribbon and pull it off. When ink sticks on the adhesive, you have found the ink side. At the end of this video, the test is shown in real-life.
Feel free to contact us anytime for any questions you may have.