Use of a microcrystalline polyamide to obtain a particular surface finish

Abstract

The present invention relates to the use of a microcrystalline polyamide for obtaining an object having all or part of its outer surface formed from this microcrystalline polyamide and having a particular surface finish, in which: the manufacture of the object comprises steps carried out hot between the Tg (glass transition temperature) and the Tm (melting point) of this microcrystalline polyamide; the transparency of the microcrystalline polyamide is such that the light transmission at 560 nm on a polished object 1 mm in thickness is greater than 80%, advantageously greater than 88%, the transparency being measured on the object obtained by standard processing methods, such as injection moulding and sheet extrusion/calendering. Advantageously, the microcrystalline polyamide is such that its degree of crystallinity is greater than 10% and less than 30% (1st DSC heating according to ISO 11357 at 40° C./min) and the enthalpy of melting is greater than 25 J/g and less than 75 J/g (1st DSC heating according to ISO 11357 at 40° C./min). Preferably, it such that its Tg (glass transition temperature) is between 40° C. and 90° C. and its Tm (melting point) is between 150° C. and 200° C. Advantageously, it results from the chain-linking of monomers such that 50% or more, by weight, of these monomers are ≧C9 monomers (i.e. having a number of carbon atoms equal to 9 or higher).

Dependencies are inferred from the claim text.