Wash-resistant copolymer

A copolymer having amide structural elements and polyether structural elements and containing at least one structural element A, at least one structural element B and at least one structural element C, wherein:

• structural element A is an aliphatic amide repeat unit selected from a structural element obtained from at least one amino acid, a structural element obtained from at least one lactam, and a structural element X1.Y1 obtained from the polycondensation of at least one linear aliphatic diamine designated X1 and at least one linear aliphatic dicarboxylic acid designated Y1,
• structural element A containing 10 or more carbon atoms,
• structural element B is an aliphatic amide repeat unit selected from a structural element obtained from at least one amino acid, a structural element obtained from at least one lactam, and a structural element X2.Y2 obtained from the polycondensation of:
• at least one diamine designated X2, said diamine being selected from a linear or branched aliphatic diamine, a cycloaliphatic diamine, and a mixture thereof, and
• at least one dicarboxylic acid designated Y2, said diacid being selected from an aliphatic diacid and a cycloaliphatic diacid,
• structural element B containing from 6 to 36 carbon atoms,
• structural element A being different from structural element B,
• structural element C is a repeat unit of the formula X3.Y3 obtained from the polycondensation of at least one polyethylene glycol diamine and/or at least one polypropylene glycol diamine designated X3 and having a molecular weight of between 200 and 1000 g·mol−1 and a linear aliphatic dicarboxylic acid designated Y3,
• structural element A representing at least 30% by weight relative to the total weight of the copolymer,
• the melting temperature being between 75 and 130° C., as measured by DSC (differential scanning calorimetry) according to standard ISO 11357-3 (2013),
• the melt flow index being between 5 and 200 cm3/10 min, measured at 160° C. under a load of 2.16 kg, determined according to standard ISO 1133-1 (2011), and
• the film tensile modulus being less than 200 MPa, as determined according to standard ISO 178 (2010).