DYE COMPOSITION COMPRISING A PARTICULAR AMPHOTERIC SURFACTANT AND A PARTICULAR THICKENING POLYMER

The present invention relates to a composition for dyeing keratin fibres, comprising: a) one or more liquid fatty substances; b) one or more amphoteric surfactants of formula (I) below: Ra′-C(0)-NH-CH2-(CH2)n-N(B)(B′)(I) in which: B represents the group -CH2-CH2-O-X′; B′ represents the group -(CH2)ZY′< with z=1 or 2; X′ represents the group -CH2-C(O)OH, -CH2-C(O)OZ′, -CH2-CH2-C(O)OH or -CH2-CH2-C(O)OZ′, or a hydrogen atom; Y′ represents the group -C(O)OH, -C(O)OZ″, -CH2-CH(OH)-S03H or the group -CH2-CH(OH)-S03-Z″; Z′ and Z″ represent, independently of each other, a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine; Ra′ represents a C10-C30 alkyl or alkenyl group derived from an acid Ra′-C(O)OH, which is preferably present in copra oil or in hydrolysed linseed oil, an alkyl group, especially a C17 group and its iso form, or an unsaturated C17 group and n represents an integer ranging from 1 to 10 and preferably from 1 to 5, or quaternized forms thereof; c) one or more thickening polymers chosen from polymers bearing sulfonic unit(s), polymers bearing sugar unit(s) and mixture thereof; d) one or more oxidation dye precursors and e) one or more chemical oxidizing agents, The present invention also relates to a process using this composition. The present invention relates to a composition for dyeing keratin fibres, comprising: a) one or more liquid fatty substances; b) one or more amphoteric surfactants of formula (I) below: Ra′-C(O)-NH-CH2-(CH2)n-N(B)(B′)(I) in which: B represents the group -CH2-CH2-O-X′; B′ represents the group -(CH2)ZY′, with z=1 or 2; X′ represents the group -CH2-C(O)OH, -CH2-C(O)OZ′, -CH2-CH2-C(O)OH or -CH2-CH2-C(O)OZ′, or a hydrogen atom; Y′ represents the group -C(O)OH, -C(O)OZ″, -CH2-CH(OH)-SO3H or the group -CH2-CH(OH)-SO3-Z″; Z′ and Z″ represent, independently of each other, a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine; Ra′ represents a C10-C30 alkyl or alkenyl group derived from an acid Ra′-C(O)OH, which is preferably present in copra oil or in hydrolysed linseed oil, an alkyl group, especially a C17 group and its iso form, or an unsaturated C17 group and n represents an integer ranging from 1 to 10 and preferably from 1 to 5, or quaternized forms thereof; c) one or more thickening polymers chosen from polymers bearing sulfonic unit(s),