Bayer MaterialScience develops tailor-made PU systems for direct skinning in auto interiors

01-Apr-09

Bayer MaterialScience has developed what its calls 'direct skinning' process for automotive interiors with a view to meet enhanced demands related to color, surface structure, feel and design. The process combines thermoplastic injection molding with the reaction injection molding (RIM) of polyurethane processing and uses one- or two-cavity molds. In the latter case, a molded part is injection-molded into the first cavity before it is moved, for example, to a second one. Once the mold is closed, a polyurethane system is then inserted using a polyurethane mixing head. While it is left to harden on the thermoplastic component, a turntable mold, for example, can be used to enable the next molded part to be produced in the first cavity. This procedure facilitates high productivity with short cycle times. Unlike conventional injection molding with subsequent surface treatment, direct skinning requires no separate coating system, because the component is produced in a multi-stage process in a single mold. BaySystems have specifically developed Bayflex® LS systems (Light Stable) for direct skinning process. These PU systems are said to exhibit excellent scratch and abrasion resistance required for the application. Also, the test results related to heat aging and light resistance tests indicate that there should be no surface flaws, discoloration or deviation in hardness in continuous operation. In addition, the Bayflex® LS systems boast outstanding UV stability, thus enabling RIM surfaces to be designed in bright colors, too.