Method for straightening human hair fibers using heating means and an a-keto acid derivative

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 alpha-hydroxy and/or keto acid derivative, the pH of said composition being not more than 9 (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 human hair fibers, comprising: applying to the hair fibers a hair-relaxing composition comprising, as the sole hair-relaxing agent, pyruvic acid ##STR00008## wherein the pH of the hair-relaxing composition is less than or equal to 9, and heating the hair fibers to a temperature ranging from 110 C. to 250 C.

2. The process of claim 1, wherein the pH of the hair-relaxing composition is less than or equal to 7.

3. A process according to claim 1, wherein the hair fibers are heated to a temperature ranging from 120 C. to 220 C.

4. A process according to claim 3, wherein the hair fibers are heated to a temperature ranging from 140 C. to 220 C.

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

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

7. The process according to claim 1, wherein the molar concentration of pyruvic acid is from 2 to 8 M.

8. The process according to claim 7, wherein the molar concentration of pyruvic acid is from 4 to 8 M.

9. A kit comprising at least: heating apparatus that provides a temperature ranging from 110 C. to 250 C., a hair-relaxing composition comprising, as the sole hair-relaxing agent, pyruvic acid ##STR00009## wherein the pH of the hair-relaxing composition is less than or equal to 7.

Description

EXAMPLE 1

(1) A simplified hair-relaxing composition is prepared, containing DL-lactic acid 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 pyruvic acid 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.

(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.

EXAMPLE 3

(5) A simplified hair-relaxing composition is prepared, containing pyruvic acid at a concentration of 4 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.

(6) 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 4

(7) A simplified hair-relaxing composition is prepared, containing L-lactic acid at a concentration of 4 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.

(8) 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.