DÜSSELDORF, GERMANY (Dec 5, 9:15 a.m. EST) — A new laser-marking process is attempting to do what has been difficult in the past: Use a laser to print in color on a plastic part.
Until now, using lasers for plastic printing has been a black-and-white world, said Gordon Price, account manager for the plastics business unit of Merck KgaA, a multinational maker of chemical and pharmaceutical products.
While black-and-white marking techniques have been around for decades, the use of color has always posed a problem, said Price, interviewed Oct. 25 at K 2001 in Dusseldorf.
Plastics brings thorny issues to color laser-marking: Laser beams can pass straight through plastic due to the material's transparency, the contrast is normally inadequate and some material has a tendency to crack or blister, said Price, who is based in Poole, England.
“To the best of my knowledge, it hasn't been done very successfully,” said Price, whose Merck division makes color pigments and additives for resins. “It's always been difficult. We're trying to change that.”
Meanwhile, many processors have turned to etching, embossing or engraving to print on a part. Yet, those techniques also alter the surface finish, while laser-marking leaves the surface unblemished, Price said.
Merck, based in Darmstadt, Germany, found several partners to help challenge existing laser-marking assumptions and open a more colorful vista to processors.
The company has launched a joint venture, announced during K 2001, with a start-up laser manufacturer, Thermark Corp. of Oxnard, Calif., to commercialize a new color laser-marking process. A third partner is Tesa AG, a Hamburg, Germany-based maker of laminating film and coatings. Those laminates are a cornerstone of the color-marking process.
The new process starts with the application of multilayer film, currently made from PET, on the part's surface. The special transfer film from Tesa, applied with a self-adhesive, includes contrast- and color-creating pigments supplied by Merck.
The part then passes inside a tabletop laser machine, looking like a small oven or kiln and costing no more than $100,000, said Stefan Grab, an account manager for Thermark.
In the machine, a solid laser, generated by an yttrium-aluminum garnet crystal, passes over the coated part. The laser beam is programmed by an operator on a computer keyboard to create a permanent marking on the part, while the pigment determines the color choice.
The coated plastic reacts to the laser and transfers the image to the part's surface without distortion, Grab said. The film is removed after marking, after the part is taken out of the laser device.
The relatively simple process can be used for a variety of differently sized parts, Grab said. It can also be adapted to many manufacturing environments, he added.
Thermark was established four years ago and received a patent for its laser-marking technology in June 2000. The company also offers similar techniques for glass, ceramic, steel and aluminum. But plastics brings great opportunity, Grab said.
“It works sort of like a Xerox machine for plastic parts,” Grab said. “It very simple to use.”
Placing the high-contrast color marks on plastic materials, using the heat generated by the low-power laser, takes seconds. The whole process from start to finish can be done in under 20 minutes, Grab said.
In March, Thermark moved to a new plant and distribution center where it is selling its equipment both separately and with partners.
Merck will take the lead in marketing the plastics process, working from its North American pigments division, called EM Industries Inc., in Hawthorne, N.Y. The company's Iriodin color-intensive pigments will be marketed to customers using the laser technology, Price said.
Customers in many industries could find the laser-marking technique attractive, he added. Major markets include packaging, especially for items that require batch- and shelf-life data marked on their containers and for personalized decoration and imaging.
Merck also is targeting electronics, automotive and medical applications for the color-marking process.
Merck's pigments division is a small piece of the company's much-larger pharmaceutical and specialty chemical operations. Merck recorded $6.3 billion in sales last year and controls 170 subsidiary companies in 50 countries.
