LANXESS offers new polyamide and polyester materials for laser transmission welding

HC Plastics News:

Laser transmission welding is increasing in the commercial production of complex shaped plastic parts for the automotive, electrical/electronic, information technology and consumer industries. As a result, material supplier LANXESS is expanding its range of laser-transparent PA6 and PA66 and PBT compounds. “Our new products are focused on the growing demand for drive and autonomous driving assistance systems for automotive electrification such as sensor housings, control components and display systems,” explains Frank Krause, welding process specialist at LANXESS's Performance Materials business unit. All new compounds are characterized by high transparency for near-infrared lasers.

Flame-retardant, tough, corrosion-resistant PA laser welding grades for automotive applications

In this process, the laser beam passes through a laser-transparent component and is then absorbed by another, typically black, component. The heat generated melts the surface of the second component. The surface of the first component is also melted by heat conduction, so that a material that is joined in the form of a weld is created between the two components. This process has several advantages: it is easy to automate, and it has less thermal and mechanical stress than vibration, ultrasonic and infrared welding. It allows the connection of 3D contours and hard/soft material combinations. Depending on the size of the component, the cycle time is quite short, less than 30 seconds. The welding flash, if any, is also very low. In addition, the welded joints are not threaded, which means that the welded liquid containers do not need to be cleaned after production.

A highlight of the new LANXESS compound is the halogen-free flame retardant Durethan AKV30FN04LT. The relatively high light transmission laser welding of PA66 has a wavelength range of typically 1.5 mm. “The heat input in the boundary layer is therefore very fast and the connection area can also melt quickly, which guarantees the economic viability of production,” Krause said. According to the UL94 standard of the United States, the compound has high leakage resistance and achieves an optimum level of V-0 (0.4 mm) in the flammability test. The flame retardancy is optimized while maintaining thermal stability. Therefore, the risk of deposits formed on the surface of the mold during injection molding is rather low. This compound contains a metal- and halide-free heat stabilizing system so that it has a lower tendency to corrode when in contact with conductive parts. This is important for components of high voltage batteries or safety switches.

Three other new PAs have also been optimized to reduce the tendency for electrical corrosion. Durethan AKV25H3.0LT is particularly suitable as a material for high and short term heat load components. PA66 is a glass fiber reinforced grade material that enhances thermal stability by the addition of non-metallic and halogen-free heat stabilizers. On the other hand, Durethan B31SKH3.0LT is an unreinforced PA6 that can be used for parts that require high toughness. For components that require very high deformation and shrinkage, the Durethan BG30XH3.0LT is the ideal material – such as a gold-silver wire electronic housing or connector strip. PA6 adds a mixture of glass fibers and micro glass beads to enhance performance.

LANXESS' innovative products in polyester are the Pocan C1202LT and C3230LT. Both materials are a mixture of PBT and PC. The ratio of amorphous PC produces excellent laser transparency even at thicker walls. The advantage of the unreinforced Pocan C1202LT is its high toughness and low warpage. It has been used in the production of tailgate handle systems for waterproof sealed electronics. Pocan C3230LT has a glass fiber weight of 30% and is suitable for applications requiring high stiffness and strength, such as electronic housings. Despite the use of glass fiber reinforced materials, the deformation is small and the surface quality is good.

In addition, new laser-transparent PBT products with good hydrolytic stability have also been well developed. “These materials are a challenge for us because the additives used to stabilize the hydrolysis usually reduce the transparency of the laser,” explains Krause. A potential application for this new product is a geometrically complex housing in the engine compartment, sensors and control elements exposed to temperature and humidity.

Editor in charge: Yao Chunlin

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