New polyamides and polyesters for laser transmission welding introduced

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Laser transmission welding is becoming increasingly established in the series production of complex shaped plastic parts for the automotive, electrical/electronic, IT, and consumer industries. LANXESS is therefore expanding its range of laser-transparent polyamide 6 and polyamide 66 as well as PBT compounds (polybutylene terephthalate) for this forward-looking technology. “With these new products, we are primarily targeting the growing demand for housings for sensors, control units, and display systems, for example, which are needed for electrification of vehicle drives and for applications in driver assistance systems through to autonomous driving,” explains Frank Krause, welding technology expert in the High Performance Materials (HPM) business unit at LANXESS.

Can be automated, is gentle, flexible, and lint-free

In the procedure, a laser beam is sent through a laser-transparent component and absorbed by a second, often black-pigmented component below. This generates heat that melts the surface of the second component. The surface of the first component also melts through heat conduction, so that a material-joining in the form of a weld is created between the two components. The process has several advantages: Thus, it is easy to automate and, compared to vibration, ultrasonic, and infrared welding it is thermally and mechanically less stressing. It allows the joining of 3D contours and hard/soft material combinations.

Flame-retardant and easy to process

One highlight among the new compounds from LANXESS is the halogen-free flame-retardant Durethan AKV30FN04LT. The light transmission for this polyamide 66 is comparatively high in the wavelength range usual for laser welding at wall thicknesses of up to 1.5 millimeters. “The heat input at the boundary layer is thus fast, so that the joining area also melts quickly, which makes economical production possible,” says Krause. The compound shows a very high tracking resistance and achieves the best classification of V-0 (0.4 millimeters) in flammability testing pursuant to the United States’ UL 94 (Underwriter Laboratories Inc.) standard. Its flame-retardant package is optimized with regard to its thermal stability.

Tough and low shrinkage

Three other new polyamides have also been optimized for a low tendency to electrocorrosion. Durethan AKV25H3.0LT is particularly suitable as a material for components with high short-term thermal loads. The polyamide 66 is glass fiber reinforced and thermostabilized with a metal- and halogenide-free heat stabilizer. Durethan B31SKH3.0LT, on the other hand, is an unreinforced polyamide 6 and is predestined for components with high toughness requirements.

Good laser transparency even with thicker walls

Product innovations in polyesters are Pocan C1202LT and C3230LT. Both materials are blends of PBT and polycarbonate (PC). The proportion of amorphous polycarbonate results in excellent laser transparency even with thicker walls. The strength of the unreinforced Pocan C1202LT is its high toughness and low warpage. It is already being used in the production of a tailgate handle system with waterproof sealed electronics. Pocan C3230LT contains 30 percent by weight of glass fibers and is designed for applications that require good stiffness and strength, such as electronic housings. Despite the glass fiber reinforcement, it has low distortion and produces good surface qualities.

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