Multistage polymer powder composition, its method of preparation and use

A polymer composition in the form of polymeric particles having a multilayer structure, said polymeric particles comprising:

• at least one stage forming a layer (B) comprising polymer (B1) which is a (meth)acrylic polymer having a glass transition temperature between 80° C. and 150° C. and
• at least one stage forming an external layer (A) of the multilayer structure, said external layer (A) comprising polymer (A1) having a glass transition temperature between −50° C. and 50° C. and wherein the polymer (A1) comprises at least 50 wt % of polymeric units coming from ethyl acrylate monomer,
• said polymeric particles obtained by a multistage process, wherein the weight ratio r in wt % of the external layer (A) comprising polymer (A1) in the polymer particles, for a Tg between 200K and 333K of polymer (A), is defined by the following formula
• r=b1ea1T
• wherein the variable T is the glass transition temperature Tg expressed in Kelvin of the polymer (A1) of the external layer (A), exponent a1 is at least 0.0255 and at most 0.028 and factor b1 is at least 0.0055 and at most 0.007,
• and wherein the mass average molecular weight Mw of the polymer (A1) is less than 500,000 g/mol.