Laser marking pharmaceutical and edible products

Color-change specialist Sherwood Technology (Widnes, Cheshire, UK) has been awarded a U.S. patent for its method of laser marking edible products. This new-generation coding, marking, and printing additive allows a safe, high-contrast image to be formed onto edible products in the pharmaceutical and confectionery industries such as pills, capsules, and hard-shelled sweets. The process utilizes a unique chemistry that reacts with a beam of low-power laser light, changing color, and thereby creating an image. This on-demand digital imaging process allows variable text and images to be printed sequentially in real time.

According to the company, previously the most common method of marking pills or hard-shell confectionery products required a mechanical embossing or surface printing method, both of which result in a significant number of rejects due to damaged/cracked product. Non-contact printing methods such as inkjet are largely unsuitable due to the spread of the ink droplets and slow drying of the ink. Problems associated with these methods include maintenance and production line downtime, in addition to issues associated with maintaining printing apparatus and replacing consumables.

With the new process, the additives, which come in the form of a dry powder or water-based solution, are applied to the surface of the confectionery or tablet as part of an existing or additional coating process. The coatings are often applied in a spray system/tumble coating and then marked by a low-power CO2 marking laser. The coating undergoes a chemical color change, creating a high-contract, stable image that is 100% edible. Due to the sensitivity of the coating to the laser light, only a fraction of the normal laser output is utilized, preserving the integrity of the surface of the edible material being marked.