PET (Polyethylene Terephthalate) is a plastic material commonly used in the beverage industry, especially for plastic cups, but also in other industries such as textiles. Although it will be banned for single-use applications, today it is still a widely used material, and it will continue to be used for reusable products since it becomes more and more recyclable. Its main application is transparent plastic, which is achieved through rapid cooling in the manufacturing process. This transparent and recyclable plastic has a very special feature regarding its coding that must be taken into account when selecting the best marking laser.
When coding transparent PET with a CO2 laser, the choice of wavelength to be used is key for an optimum solution. Within the Macsa id C Series laser range, we have three different wavelengths available:
SPA CB: 10.6 µm
SPA CF: 10.2 µm
SPA CP: 9.3 µm
When we use the most common wavelength, 10.6 µm, or its close variant of 10.2 µm, the reaction of the laser on the PET results in engraving, which generates a transparent mark and weakens the material. However, when we use a 9.3 µm wavelength, the reaction between the material and the radiation is one of foaming, in which a white foam is generated that provides greater contrast and greater protection for the container.
This difference in reactions is clearly advantageous both in maintaining the integrity of the package, avoiding any risk of carbonated drinks exploding from internal pressure, and in coding the package, where we have a much more visible brand to the customer. Whether the aim is to code an expiry date, or an advertising logo, as in the example of this application, coding with the SPA CP 30 laser makes it possible to add value to plastic cups in a simple and effective way.
Left: Foaming reaction with 9.3 µm wavelength Right: Engraving reaction with 10.6 µm wavelength
LASER: SPA CP 30
LENS: 100 x 100 mm
APPLICATION TYPE: Marking
PRODUCT: Plastic cups
MARKING TYPE: Static
PRODUCTION SPEED: 100 m/min