Cosmetic compositions comprising fatty acid esters of oxalkylated alkylalkylene diamines and/or their salts for hair repair treatments

A method for strengthening hair or protecting hair from damage, comprising the step of contacting the hair with a composition comprising 0.1 to 10 wt.-% of a component which is an ester of an oxalkylated alkylalkylene diamine of formula (I)

• wherein
• R is C5-C24-alkyl or C8-C24-alkenyl
• A is a group —C2H4— or —C3H6—,
• Z1 is a group —C(O)—R′, wherein R′ is C5-C35-alkyl or C5-C35-alkenyl,
• Z2 is a group —C(O)—R″, wherein R″ is C5-C35-alkyl or C5-C35-alkenyl,
• Z3 is a group —C(O)—R′″, wherein R′″ is C5-C35-alkyl or C5-C35-alkenyl,
• Z4 is a group —C(O)—R“ ”, wherein R“ ” is C5-C35-alkyl or C5-C35-alkenyl,
• a is 0 or 1,
• m is 2 or 3,
• u, v, w and x are each independently numbers from 1 to 9,
• where the sum of u, v and w being from 3 to 30, if a=0, and
• where the sum of u, v, w and x being from 4 to 35, if a=1,
• and/or a quaternized salt thereof.