PVC card printers primarily work using one of three processes: dye sublimation, reverse transfer, or pigment ink printing. Each method offers distinct advantages and is suitable for different applications.
Dye Sublimation Printing
Dye sublimation is a common technique used in PVC card printers. Here's how it works:
- Heating the Ribbon: The printhead uses tiny heating elements to precisely heat a ribbon that contains colored dyes (typically CMYK - Cyan, Magenta, Yellow, and Black).
- Vaporizing the Dye: The heat causes the solid dyes to vaporize (sublimate) into a gaseous state.
- Diffusion into the Card Surface: This gaseous dye then diffuses directly into the surface of the PVC card. The heat allows the pores of the PVC to open, allowing the dye to penetrate.
- Permanent Bond: As the card cools, the pores close, trapping the dye and creating a permanent, continuous-tone image. This produces high-quality, vibrant images with excellent durability.
Reverse Transfer Printing (Retransfer)
Reverse transfer, also known as retransfer printing, provides superior image quality and durability, especially for cards with uneven surfaces or embedded electronics.
- Printing to a Film: The printer first prints the image in reverse onto a clear transfer film using dye-sublimation.
- Applying the Film to the Card: Then, heat and pressure are used to bond this film to the surface of the PVC card.
- Edge-to-Edge Printing: This process allows for true edge-to-edge printing, meaning the entire surface of the card can be covered without leaving a border.
- Enhanced Durability: Because the image is printed on the film which is then bonded to the card, it is better protected from scratches and fading, resulting in a longer-lasting card.
Pigment Ink Printing
Pigment ink printing is another option, though less common than dye sublimation for standard PVC ID cards.
- Applying Pigment Ink: The printer uses a printhead to spray tiny droplets of pigment-based ink directly onto the PVC card.
- UV Curing (Often): Many pigment ink PVC printers utilize UV-curable inks. After the ink is applied, the card is exposed to ultraviolet (UV) light. This UV light causes the ink to harden and bond to the surface of the card.
- Increased Fade Resistance: Pigment inks offer superior fade resistance compared to dye-based inks, making them suitable for applications requiring long-term durability, particularly in outdoor environments.
- Image Quality: The image quality of pigment ink printers is good; however, it may not achieve the same level of vibrancy and continuous tones as dye-sublimation or retransfer printers.
In summary, PVC card printers use different methods to transfer images onto cards, each with its own strengths in terms of image quality, durability, and application. Dye sublimation is common for general-purpose ID cards, reverse transfer excels in high-quality, durable, edge-to-edge printing, and pigment ink provides excellent fade resistance.
