Method for straightening keratinous fibres using heating means and an amide

Abstract

The invention concerns a method for straightening keratinous fibers including: (i) a step of applying on the keratinous fibers a hair straightening composition containing at least one cyclic or linear amide, (ii) a step of increasing the temperature of the keratinous fibers, using heating means, to a temperature ranging between 110 and 250 C.

Claims

1. A process for relaxing keratin fibers, comprising: applying to the keratin fibers a hair-relaxing composition comprising, as the sole hair-relaxing agent, at least one cyclic amide at a molar concentration ranging from 2 M to 8 M, wherein the pH of said composition is less than or equal to 9, heating the keratin fibers to a temperature ranging from 110 C. to 250 C., wherein the at least one cyclic amide is chosen from: 2-pyrrolidone, pyroglutamic acid, 3-methyl-2-pyrrolidone, 5-methyl-2-pyrrolidone, 5-(hydroxymethyl)-2-pyrrolidinone, 5-aminomethylpyrrolidin-2-one, 4-hydroxy-2-pyrrolidinone, and the stereoisomers, organic or mineral salts, and/or solvates thereof; wherein the hair-relaxing composition does not comprise a reducing agent; and wherein the process does not comprise a reducing step.

2. The process according to claim 1, wherein the at least one cyclic amide is a solvate.

3. The process according to claim 1, wherein said keratin fibers are heated to a temperature ranging from 120 C. to 220 C.

4. The process according to claim 3, wherein said keratin fibers are heated to a temperature ranging from 140 C. to 220 C.

5. The process according to claim 1, wherein the composition is applied to wet keratin fibers.

6. The process according to claim 1, wherein the fibers are partially predried.

7. The process according to claim 1, wherein the molar concentration of the at least one cyclic amide ranges from 6 M to 8 M.

8. The process according to claim 1, wherein the molar concentration of the at least one cyclic amide ranges from 4 M to 8 M.

9. The process according to claim 1, wherein the pH of the composition is less than or equal to 7.

10. A process for relaxing keratin fibers, comprising: applying to the keratin fibers a hair-relaxing composition comprising, as the sole hair-relaxing agent, 2-pyrrolidone or organic or mineral salts thereof, wherein the pH of said composition is less than or equal to 9, and heating the keratin fibers to a temperature ranging from 110 to 250 C.; wherein the hair-relaxing composition does not comprise a reducing agent; and wherein the process does not comprise a reducing step.

Description

EXAMPLE 1

(1) A simplified hair-relaxing composition is prepared, containing 2-pyrrolidone at a concentration of 8 M in water, as hair-relaxing active agent. This composition is applied to naturally curly African hair for 15 minutes at a temperature of 40 C., and the hair is then rapidly towel-dried.

(2) Lock-by-lock straightening of the head of hair is then performed using a flat iron heated to 180 C., for 10 to 15 seconds. The hair is efficiently relaxed and feels soft.

EXAMPLE 2

(3) A simplified hair-relaxing composition is prepared, containing 2-pyrrolidone at a concentration of 6 M in water, as hair-relaxing active agent. This composition is applied to naturally curly African hair for 25 minutes at a temperature of 40 C., and the hair is then rapidly towel-dried.

(4) Lock-by-lock straightening of the head of hair is then performed using a flat iron heated to 180 C., for 10 to 15 seconds. The hair is efficiently relaxed and feels soft.