Process for overmoulding over a plastic insert and automobile part obtained by this process

1. A process for manufacturing a composite automobile part comprising the following successive steps:

(a) positioning an insert in a mould, said insert comprising a first plastic material; and

(b) overmoulding a layer of a second thermoplastic material over at least one surface of said insert to obtain the composite automobile part,

wherein at least one of said first plastic material and said second thermoplastic material comprises an additive, said additive comprising a polymer to which carboxylic anhydride monomers are grafted;

wherein said first plastic material and said second thermoplastic material are respectively based on polyamide and based on polypropylene, or vice versa; and

wherein said second thermoplastic material is made of a polymer comprising a propylene/ethylene copolymer based on propylene and polyethylene comprising 12% by weight of talc as mineral filler and 10% by weight of an EPR type elastomer material, from 0.2% to 0.5% by weight of SEBS and from 5% to 10% by weight of polypropylene grafted with maleic anhydride monomers.

2. The process according to claim 1 , wherein said moulding step is an injection moulding step.

3. The process according to claim 1 , wherein said additive is maleic anhydride, a derivative of maleic anhydride, or a combination thereof.

4. The process according to claim 1 , wherein said polymer to which carboxylic anhydride monomers are grafted is selected from the group consisting of polypropylene, high or low density polyethylene, copolymers of propylene and ethylene, a thermoplastic elastomer based on styrene-block-copolymers and combinations thereof.

5. The process according to claim 1 , wherein said second thermoplastic material comprises said additive.

6. The process according to claim 1 , wherein said first plastic material or said second thermoplastic material further comprises another additive comprising a thermoplastic polymer to which carboxylic anhydride monomers are grafted.

7. The process according to claim 1 , wherein said first plastic material and said second thermoplastic material are materials of different type.

8. The process according to claim 1 , wherein the second thermoplastic material comprises a propylene/ethylene copolymer, an elastomer, or a combination thereof.

9. The process according to claim 1 , wherein during the positioning step, the insert is not in a molten state, is at ambient temperature, or both is not in a molten state and is at ambient temperature.

10. The process according to claim 3 , wherein said maleic anhydride, the derivative of maleic anhydride or the combination thereof is present in a proportion ranging from 0.1% to 20% by weight compared with the total weight of said first plastic material, said second thermoplastic material, or combination thereof.

11. The process according to claim 10 , wherein said maleic anhydride-, the derivative of maleic anhydride or the combination thereof is present in a proportion ranging from 2% to 20% by weight compared with the total weight of said first plastic material, said second thermoplastic material, or combination thereof.

12. The process according to claim 4 , wherein the polymer is (polystyrene-b-poly(ethylene-butylene)-b-polystyrene.

13. The process according to claim 7 , wherein said first plastic material and said second thermoplastic material are materials not likely to adhere to each other satisfactorily when subjected to typical injection moulding pressure and temperature conditions.

14. The process according to claim 1 , wherein said second thermoplastic material is made of a polymer consisting of a propylene/ethylene copolymer based on propylene and polyethylene comprising 12% by weight of talc and 10% by weight of an EPR type elastomer material, from 0.2% to 0.5% by weight of SEBS and from 5% to 10% by weight of polypropylene grafted with maleic anhydride monomers.