Thermal Transfer Printing 101

Thermal transfer printing, on the other hand, heats the marking foil and transfers the image to the object.

Furthermore, there are two different types of thermal transfer printing—a melting type that uses the ink melt generated by heating and a sublimination type that turns the ink into gas by heating. Thermal transfer printing is also called “wax printing” or “image printing.”

Apart from this, there are three types of marking foils used by thermal transfer printers: wax-based ribbons, resin-based ribbons, and wax-resin type.

While wax-based ribbons have a relatively low ink melting temperature, resin-based marking foils have a higher melting temperature (relative to wax-based type) and are more resistant to heat, abrasion, and chemicals. As a result, prints produced by the latter are more suitable for long-term storage purposes.

Meanwhile, wax-resin type inks possess the characteristics of both wax and resin types. Therefore, customers can select the ratio of wax to resin that best fits their desired application.

Types of Thermal Printing

The advantages and disadvantages of direct thermal and thermal transfer printing are presented below.

Direct Thermal Printing

Direct thermal printing uses a thermal printhead that heats the thermal paper directly on contact.

Thermal paper is a special type of paper that develops color when heat is applied to its surface.

It is widely used by monochrome mobile label printers to print barcodes/prices of merchandise and by fax machines.

Advantages

Since thermal paper itself develops colors, ink is not necessary in direct thermal printing.

Effectively, this eliminates the need to purchase ink on a regular basis, thereby reducing running costs.

Disadvantages

Direct thermal printing can print only on thermal paper, which has low weather resistance (relative to other methods of printing), and its colors tend to fade over time.

This may limit the use of direct thermal printers for indoor and short-term labels and receipts.

Moreover, the printing colors are limited to black, dark blue, or sepia. Since thermal paper reacts to frictional heat, simply rubbing the paper ends up generating color on it.

Thermal Transfer Printing

Thermal transfer printing is conducted by applying a thermal printhead to a film-like marking foil for heating specific areas.

This activates the heated area of the marking foil, causing the ink to migrate to the object and adhere to it. The melting type thermal transfer printing prints by melting ink, while the sublimation type prints by turning the ink into gas.

Advantages

The advantages of thermal transfer printers over direct thermal printers include the availability of marking foils in a wider range of colors, the ability to print on non-thermal papers (e.g., general paper and resin), and more flexibility in terms of printable materials.

Furthermore, since they are more weather-resistant than direct thermal printers, they are more suitable for outdoor or long-term use cases.

Disadvantages

Thermal transfer printing uses consumables, such as marking foils, that needs to be purchased periodically.

Moreover, thermal transfer printers are bigger in size than direct thermal printers, since they involve the use of more components, such as the marking foil.

Durability of Thermal Print

The weather resistance test is a significant metric that can be used to accurately evaluate printing. This test examines the time taken for printed characters to fade after being exposed to ultraviolet light or water spray.

While this test can simply be conducted by exposing prints to the air, this process may take several years to complete. Therefore, a dedicated machine is used to accelerate this deterioration and then evaluate the results within a shorter period of time.

In this context, all genuine CTK Hotmarker consumables have been subjected to JIS（Japan Industrial Standards）-based accelerated weathering tests to ensure that they meet in-house durability standards.

The thermal printhead is a key component that comprises a heat-generating element at its end, which heats the marking foil to transfer images onto the object.
The thermal printhead of CTK’s SP series is divided into three sections, where each section can be used one at a time.

Thus, when a phenomenon known as "dot loss" (i.e., when some part of the print is missing from the object) occurs after a printer has been used for a prolonged period of time, the user can switch to employing the unused section of the thermal printhead.

In inkjet printing, ink particles ejected from a nozzle are deflected by an electrode and sprayed onto the printing surface.

Unlike thermal printers, these printers can carry out printing without direct contact. Hence, they can be used to print on objects of all shapes and sizes, such as film, PET bottles, and cans for packaging.

However, thermal transfer printing is more environmentally friendly than inkjet printing because it uses inks containing organic solvents that release only a small amount of environmentally hazardous substances into the air when it dries.

Another reason why thermal transfer printing is more advantageous than inkjet printers is that the latter requires the cleaning of ink tanks and nozzles after each color change, while color changes in the former can be easily achieved by simply replacing the marking foil.

Hot stamping, in which the type is pressed directly onto the substrate, enables simultaneous printing and engraving, resulting in highly durable printing. However, in this case, the type needs to be replaced every time the printing content is changed.

In the laser printing method, a laser beam amplified by an oscillator is irradiated onto the object, thus enabling non-contact printing similar to inkjet printing. In addition, since marking foils are not used in laser printing, the cost of consumables can be reduced.

On the other hand, laser printers suffer from disadvantages such as high installation costs, time-consuming focal length setting of the laser beam, the fact that only oxidized colors of the printing piece can be printed, and the environmental impact of combustion gas emissions during oxidation.

In comparison, thermal transfer printers have many advantages.

How to Choose a Thermal Transfer Printer

When choosing a thermal printer, the following key factors should be considered:

1. Processing capacity and production volume

Processing capacity is expressed in terms of the distance processed per second.

The processing capacity of CTK thermal printers is 27mm/sec (SP8600).

2. Total cost

In addition to the initial cost of purchasing the equipment, one should also consider that running costs will be incurred while operating the machine.

These costs include expenditures on consumables, such as marking foils, and replacement of components (such as spindles) that may occur when the machine remains in use for prolonged periods. marking foil. Therefore, estimating the total cost must include both the initial cost and the running costs.

3. Shape of works

Product specifications vary depending on the type of work. CTK's SP series thermal printers can handle three types of work: marker tubes, marker labels, and marker plates (terminal nameplates).

Furthermore, the SP series printers can print on marker tubes with non-planar shapes by flattening the marker tube using the press roller that comes equipped with this series of printers.

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