additives | Laser marking and welding

laser beam creates marks around 10 microns beneath the plastic surface. Due to the low dosages, the company says that Budit L makes the marking of transparent polymers possible. In laser contour welding, in particular, gaps may


Schematic showing how Budenheim’s foamable Budit additives can act as gap- fillers in welding applications

sensitive additives for polymers with high selective absorption that creates excellent results in processing speed, marking contrast and strength of welding seams. There is a crucial need for eco-friendly ingredi- ents and safe permanent marking of parts with food contact or medical devices.”

Industrial drivers

Budenheim identifies a number of influences driving new additives for laser technology, including the need for clean and contactless marking; permanent marking with a resistance to solvents, humidity and abrasion; high flexibility and indelibility of marking; high speed and cost savings. Additives for laser welding help system designers to achieve extra tight and strong welded seams without the use of glue and gapless laser contour welding is being used to make permanent joints in medical devices, industrial and consumer electron- ics, as well as automotive components. “For both laser marking and welding applications,

Right: Eckart’s antimony free LaserSafe

additives have been developed for high

contrast laser marking


the industry is looking for eco-friendly materials and the establishment of strong regulations,” says Buden- heim Product Manager Hendrik Wermter. “The chemical basis of Budenheim laser active pigments is purely inorganic. The material complies with the strictest standards. Budit L is antimony-free and safe for medical and food contact applications. These include printing of best-before dates and codes on food packaging or bottle caps, serial numbers on technical parts or electronical components, resistant bar codes and cattle ear tags.” Budenheim has developed a range of laser-sensitive

additives that enable advanced high-contrast laser marking and laser welding for a wide range of thermo- plastics. The Budit L Series is claimed to be easy to add and process, and provides a laser marking pigment with good selective absorption in the NIR. This is accompa- nied by a high transparency in the visible range. The product is designed for lasers at a wavelength of 800-1800 nm emittance. Depending on the energy level, different visual marks from bright to dark can be generated on the polymer surface. Using a typical concentration of 0.1 to 5.0% Budit L, the energy of the

70 COMPOUNDING WORLD | February 2017

occur between the parts and in such cases the weld seam may show a fusion defect, leading in turn to a sometimes considerable reduction in weld strength. Combining light absorbing functions with foaming properties, the Budit L Series for laser welding ensures gap-bridging and gap-less joining of moulded parts, says the company. The special formulation results in volume expansion and foaming of the absorbent polymer. The radiation energy of the laser beam is used to heat the polymer matrix locally, simultaneously initiating the reaction of the LIF (laser induced foaming) ingredient. This foaming of the polymer matrix is limited only to the area of the laser beam. Budenheim says that joint gaps up to 150 microns can be closed and filled by the foamed polymer, resulting in extra tight and strong bonds. Budit L is supplied in a concentrate form. “Powder

product can be difficult in processing, especially in small dosages,” Wermter says. “Therefore, Budit L is designed as a single pigment concentrate, with high concentrations of the functional pigment based on universal carrier polymers. For a masterbatcher, as well as compounders, it is an easier way to include the pigment and produce a final masterbatch with specific colour and additive targets.”

Ecological developments Eckart says its latest LaserSafe line of marking additives, which are based on heavy metal-free pigments rather than antimony oxide, are suitable for a wide range of eco-friendly applications. The company says high-contrast laser markings can be achieved at high speed and superior quality with the additives, which can be used for traditional identification and

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