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7th August 2018
Direct thermal printing uses chemically treated, heat-sensitive media that blackens when it passes under the thermal printhead. Direct thermal printers have no ink, toner, or ribbon. Direct thermal materials offer a shorter life than thermal transfer and may fade over time. Direct thermal labels offer minimal resistance to heat, light, abrasion, and chemicals.
Exposure to these items will cause the material to darken, resulting in the text and barcodes that are unreadable. For these reasons, direct thermal printing is not used for demanding applications.
In thermal transfer printing, a thermal printhead applies heat to a ribbon, which melts ink onto the material to form the image. This technique provides image quality and durability that is unmatched by other on-demand printing technologies.
Thermal transfer offers a wider variety of materials than direct thermal, including paper, polyester, vinyl, polypropylene and polyimide materials. Thermal transfer solutions are much more durable than direct thermal, as they are resistant to a wider variety of temperatures and chemicals. To obtain resistance to very demanding environments, the specific label material and ribbon must be carefully matched.
By selecting the right material-ribbon combination, as well as specialty adhesives, users can create archival-quality labels to withstand temperature extremes, ultraviolet exposure, chemicals, sterilization, and more. Thermal transfer ribbons are available in wax, wax-resin, and resin formulations that meet the durability requirements of a wide range of labeling applications:
In order to identify the optimal print technology, material and ribbon (if thermal transfer printing), to ensure that the label remains readable during the products safe and appropriate use and disposal, you need to consider the following:
The type and the shape of surface being labelled needs to be considered to ensure that the label remains adhered to the surface. Have you ever noticed that a specific label does not adhere as well to a plastic bin as it does to a cardboard box? This is because these items have a different surface energy. The shape of the surface is also important to consider. For example, small curved surfaces are also difficult to label, since they require a flexible material with a tight mandrel adhesive to make sure the label does not pull away from the surface
Materials and adhesives are also sensitive to very low and very high temperatures. There are two types of temperatures you need to consider, Application Temperature and Service Temperature:
Contact and rubbing will affect readability over time. If in your application, the label will come into contact with items that could scratch it and make it unreadable, a ribbon with a higher resin content will provide improved resistance.
If an applicator is to be used this must be known up front as the label must be cut differently so that it peels off properly from the liner. In addition, perforations are also not recommended as they change the stiffness characteristics of the label making the label difficult to release from the liner.
When a label will be exposed to moderate to extreme chemicals, a thermal transfer labeling solution is required. In the case of harsh and extreme chemicals, a high-durability resin ribbon is also recommended. Below is a chart of chemical classifications: Weak Chemicals Moderate Chemicals Harsh Chemicals Extreme Chemicals Window Cleaners Alcohol Gasoline Acetone Water Bleach Oil Xylene
If your product will be subjected to the elements outdoors (rain, sun, etc.), a thermal transfer synthetic material would be the optimal solution, as the label and the image provide the added durability required to survive these tough environmental factors.
Knowing how long the label will need to be readable for in addition to the environmental factors will help you identify the optimal solution. For example, if the label only requires readability for six months and does not need to resist chemicals, moisture, and abrasion, a direct thermal paper label would best meet your needs. However, if the label will be subjected to moderate chemicals and be on an item that will be stored outside for over three years, a specialty thermal transfer synthetic label would be required.
This is a key consideration, as material and ribbon selection will influence the maximum print speed. Typically, synthetic labels do not produce quality text and barcodes above 6 ips, and in order to print at 12 ips or higher a thermal transfer paper label with a high-speed wax ribbon is required.
Increasing print darkness is necessary when printing at faster speeds to get the best barcode grades and print quality. When using higher-grade ribbons, which require additional energy, a higher print darkness is also required.
Using a printer with a higher DPI is necessary when printing formats with detailed graphics and / or small fonts. However, to properly resolve the format, you will also need to use a material with a very smooth or gloss surface, such as a synthetic.
Product identification labels are now viewed as a critical mechanism for maintaining compliance, ensuring brand consistency, improving operational efficiency, and supporting business growth. They are the final link between your company and key stakeholders including customers, consumers, caregivers, patients, and regulators.