scarcity21
Well-Known Member
Kinda long but i think its a good read ....maybe one of our scientists can shed light. i had to cut and paste to try to fit in post. to read complete article, go to
http://www.wipo.int/pctdb/en/wo.jsp?wo=2003086335&IA=WO2003086335&DISPLAY=DESC
http://www.wipo.int/pctdb/en/wo.jsp?wo=2003086335&IA=WO2003086335&DISPLAY=DESC
HAIR CARE COMPOSITION FOR RESTORING THE ELASTICITY OF HAIR This invention relates to the use of a hair care composition for restoring the elasticity of hair, hair care compositions, and leave-on compositions.
In recent years, there have been employed various hair conditioning compositions for conditioning the hair, namely, imparting gloss, voluminousness and softness thereto and improving the combing properties thereof.
These hair conditioning compositions are classified into those which remain the hair conditioning components on the hair and those which are to be rinsed away after application.
None of the above-mentioned publications however, describe how the elasticity of hair can be restored. Hair is often damaged as a result of hair treatments such as bleaching, dying or permanent waving. Damaged hair has a reduced elasticity and as a result of that is dry, brittle and will easily break. With the present invention a method is provided to restore damaged hair and retain its elasticity.
We have found that hair can be restored and retain its elasticity by using a composition comprising lactic acid or a salt thereof.
The salts of the lactic acid which can be used in the present invention are not particularly restricted. Suitable salts of lactic acid which can be used are alkali metal lactates, alkaline earth metal lactates, thiolactates and ammonium lactates and/or amino acid salts of lactic acid. Salts which are especially suitable for use in the present invention are sodium lactate, calcium lactate, and potassium lactate.
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As the L-compound of lactic acid is naturally occurring in the human body, it is found to be less irritating to the skin. Therefore, the use of lactic acid or salt thereof containing L-lactic acid at a higher ratio as compared with D-lactic acid is preferred.
The preferable ratio of L-lactic acid to the total lactic acid is from 60 to 100 % by weight, more preferably from 85 to 100 % by weight.
The ratio of L-lactic acid to the total lactic acid can be determined by measuring the specific rotation of the L-lactic acid in the conventional manner. The content of L-lactic acid of 60 % by weight corresponds to an optical purity of the L-compound of 20 % ee.
At present, lactic acid is commercially available in the form of aqueous solutions containing 10 to 90 % by weight of lactic acid in the form of the D-and L-compounds or a racemic modification. These commercially available aqueous solutions may conveniently be used in the present invention. Also, it is known that L-lactic acid can be obtained by extracting fermentation products of specific plants. Aqueous solutions of the L-lactic acid obtained by the fermentation of plants sometimes contain other a-hydroxy acids.
Mixture of the other a-hydroxy acids can be also used so long as the effect of the present invention is not worsened thereby.
Examples of the a-hydroxy acids other than lactic acid which may be used in the present invention include citric acid, malic acid, glycolic acid and tartaric acid. Said other a-hydroxy acids may be used in amounts ranging from 0.05 % by weight to about 20 % by weight based on the total of the composition.
In addition to lactic acid or its salt conventionally used moisturisers such as glycerine sodium PCA, sorbitol and, lactitol can be used in the present invention. These moisturisers may be present in amounts ranging from 0.05 to 20 % by weight based on the total of the composition. Also combinations of moisturisers may be used.
It was found that the elasticity of the hair was already improved using amounts of 1 % by weight of lactic acid or salt thereof, based on the total of the composition. However, the elasticity was completely retained in comparison to undamaged hair when using at least 2 % by weight of lactic acid or salt thereof. The elasticity may be repaired by using the composition as a leave-on composition, i. e. those compositions which are used without washing away after application (e. g. , hair blow, hair spray, hair foam, styling lotion, hair gel, leave-on conditioners and hair mist) or by using the composition as a rinse-of composition, i. e. those compositions which are to be washed away after application (e. g. , shampoo, conditioner, and treatment).
Especially in the case of the hair care products to be washed away after application, but also for leave-in compositions, it may be preferred to accelerate the penetration of the lactic acid into the hair and thus improving the elasticity restoring effects by cleansing the hair surface.
Accordingly, the effects of the lactic acid can be enhanced by using anionic surfactants, amphoteric surfactants or nonionic surfactants together therewith for cleansing the hair surface.
Either one of these surfactants or a mixture of two or more thereof may be used in the present invention. The content of these surfactants based on the total weight of the hair care product preferably ranges from 3 to 60 % by weight, more preferably from 5 to 30 % by weight.
Also by the addition of cationic surfactant (s), the adsorption of the lactic acid onto the hair can be promoted and thus the elasticity restoring effects can be improved.
The content of these cationic surfactants based on the total weight of the hair care composition preferably ranges from 0.1 to 10 % by weight, more preferably from 0.5 to 5 % by weight.
The hair care composition for use in the present invention may further contain conditioning agents such as cationic polymers, ampholytic polymers, silicones and silicone derivatives. By using these components, a film is formed on the hair surface. Thus, the adsorption of the lactic acid onto the hair can be promoted and further improved elasticity restoring effects can be exerted.
In recent years, there have been employed various hair conditioning compositions for conditioning the hair, namely, imparting gloss, voluminousness and softness thereto and improving the combing properties thereof.
These hair conditioning compositions are classified into those which remain the hair conditioning components on the hair and those which are to be rinsed away after application.
None of the above-mentioned publications however, describe how the elasticity of hair can be restored. Hair is often damaged as a result of hair treatments such as bleaching, dying or permanent waving. Damaged hair has a reduced elasticity and as a result of that is dry, brittle and will easily break. With the present invention a method is provided to restore damaged hair and retain its elasticity.
We have found that hair can be restored and retain its elasticity by using a composition comprising lactic acid or a salt thereof.
The salts of the lactic acid which can be used in the present invention are not particularly restricted. Suitable salts of lactic acid which can be used are alkali metal lactates, alkaline earth metal lactates, thiolactates and ammonium lactates and/or amino acid salts of lactic acid. Salts which are especially suitable for use in the present invention are sodium lactate, calcium lactate, and potassium lactate.
.
As the L-compound of lactic acid is naturally occurring in the human body, it is found to be less irritating to the skin. Therefore, the use of lactic acid or salt thereof containing L-lactic acid at a higher ratio as compared with D-lactic acid is preferred.
The preferable ratio of L-lactic acid to the total lactic acid is from 60 to 100 % by weight, more preferably from 85 to 100 % by weight.
The ratio of L-lactic acid to the total lactic acid can be determined by measuring the specific rotation of the L-lactic acid in the conventional manner. The content of L-lactic acid of 60 % by weight corresponds to an optical purity of the L-compound of 20 % ee.
At present, lactic acid is commercially available in the form of aqueous solutions containing 10 to 90 % by weight of lactic acid in the form of the D-and L-compounds or a racemic modification. These commercially available aqueous solutions may conveniently be used in the present invention. Also, it is known that L-lactic acid can be obtained by extracting fermentation products of specific plants. Aqueous solutions of the L-lactic acid obtained by the fermentation of plants sometimes contain other a-hydroxy acids.
Mixture of the other a-hydroxy acids can be also used so long as the effect of the present invention is not worsened thereby.
Examples of the a-hydroxy acids other than lactic acid which may be used in the present invention include citric acid, malic acid, glycolic acid and tartaric acid. Said other a-hydroxy acids may be used in amounts ranging from 0.05 % by weight to about 20 % by weight based on the total of the composition.
In addition to lactic acid or its salt conventionally used moisturisers such as glycerine sodium PCA, sorbitol and, lactitol can be used in the present invention. These moisturisers may be present in amounts ranging from 0.05 to 20 % by weight based on the total of the composition. Also combinations of moisturisers may be used.
It was found that the elasticity of the hair was already improved using amounts of 1 % by weight of lactic acid or salt thereof, based on the total of the composition. However, the elasticity was completely retained in comparison to undamaged hair when using at least 2 % by weight of lactic acid or salt thereof. The elasticity may be repaired by using the composition as a leave-on composition, i. e. those compositions which are used without washing away after application (e. g. , hair blow, hair spray, hair foam, styling lotion, hair gel, leave-on conditioners and hair mist) or by using the composition as a rinse-of composition, i. e. those compositions which are to be washed away after application (e. g. , shampoo, conditioner, and treatment).
Especially in the case of the hair care products to be washed away after application, but also for leave-in compositions, it may be preferred to accelerate the penetration of the lactic acid into the hair and thus improving the elasticity restoring effects by cleansing the hair surface.
Accordingly, the effects of the lactic acid can be enhanced by using anionic surfactants, amphoteric surfactants or nonionic surfactants together therewith for cleansing the hair surface.
Either one of these surfactants or a mixture of two or more thereof may be used in the present invention. The content of these surfactants based on the total weight of the hair care product preferably ranges from 3 to 60 % by weight, more preferably from 5 to 30 % by weight.
Also by the addition of cationic surfactant (s), the adsorption of the lactic acid onto the hair can be promoted and thus the elasticity restoring effects can be improved.
The content of these cationic surfactants based on the total weight of the hair care composition preferably ranges from 0.1 to 10 % by weight, more preferably from 0.5 to 5 % by weight.
The hair care composition for use in the present invention may further contain conditioning agents such as cationic polymers, ampholytic polymers, silicones and silicone derivatives. By using these components, a film is formed on the hair surface. Thus, the adsorption of the lactic acid onto the hair can be promoted and further improved elasticity restoring effects can be exerted.
