US speciality chemicals firm Styron has unveiled what it says is the first full thermoplastic, mono-material lift-gate produced in series on the New Renault Clio that features a weight reduction of 10% and is also easily recyclable.

After a two-year development project with Styron, Renault is now launching the New Renault Clio with a thermoplastic lift-gate made with Styron’s material solutions. Previously made of steel, the lift-gate is manufactured in thermoplastic from three separate parts:

• The inner skin is injection moulded using a talc filled polypropylene compound from Styron and connects to the structural part.
• The structural part is produced with LGF-PP concentrate developed by Styron. This concentrate is diluted directly on the moulding machine with appropriate PP copolymer resin through dry-blend directly.
• The outer skin is made with Styron’s Inspire At-Press talc masterbatch concept, which injection moulds through blending of the different components (polypropylene impact copolymer, specifically designed 70% talc masterbatch and the required colour concentrate), allowing for a tailored mechanical performance to meet the OEM specific application requirements.

A lift-gate is a complex application for several reasons: It needs to fit perfectly on to the car and has numerous functions that need to be hidden (such as the hinges and the closing mechanism). Additionally, it is subjected to many external conditions such as exposure to high/low temperature in humid environment that can cause deformation issues and must then be addressed to guarantee water tightness.

To help improve impact resistance, expansion and durability of the structural part of the lift-gate, Styron used its Inspire long glass fibre polypropylene resin (LGF-PP). By increasing the glass content of the moulding material, the part is able to gain improved stiffness and toughness. In addition, Styron also supported Renault in optimising the tool-design for the machine and with selecting the appropriate plasticising screw to maintain the required fibre length after moulding the lift-gate. (PRA)