AMINO ACID BASED AMPHOTERIC SURFACTANT

Abstract

Disclosed is a novel amino acid derived surfactant which is prepared by forming the salt of an alkylaminopropionic acid and a basic amino acid such as arginine which is useful in cosmetic and personal care compositions.

Claims

1. A alkylaminopropionic acid salt of a basic amino acid of the general formula ##STR00004## where R represents a linear or branched alkyl or alkenyl group having from eight to 22 carbon atoms and AA+ represents a basic amino acid.

2. The alkylaminopropionic acid salt of a basic amino acid of claim 1 where the basic amino acid is arginine.

3. The alkylaminopropionic acid salt of a basic amino acid of claim 2 where the basic amino acid is L-arginine.

4. The alkylaminopropionic acid salt of a basic amino acid of claim 3 where the alkylaminopropionic acid is at least one of lauraminopropionic acid, cocaminopropionic acid, and stearaminopropionic acid.

5. The alkylaminopropionic acid salt of claim 4 where R represents a linear alkyl group having from 8 to 22 carbon atoms.

6. The alkyl aminopropionic acid salt of claim 5, where R represents a linear alkyl group having from 12 to 18 carbon atoms.

7. The alkylaminopropionic acid salt of claim 3 where R represents a linear alkyl group having from 8 to 22 carbon atoms.

8. The alkyl aminopropionic acid salt of claim 7, where R represents a linear alkyl group having from 12 to 18 carbon atoms.

9. The alkylaminopropionic acid salt of claim 2 where R represents a linear alkyl group having from 8 to 22 carbon atoms.

10. The alkyl aminopropionic acid salt of claim 9, where R represents a linear alkyl group having from 12 to 18 carbon atoms.

11. The alkylaminopropionic acid salt of claim 1 where R represents a linear alkyl group having from 8 to 22 carbon atoms.

12. The alkyl aminopropionic acid salt of claim 11, where R represents a linear alkyl group having from 12 to 18 carbon atoms.

13. The alkylaminopropionic acid salt of a basic amino acid of claim 1s where the mole ratio of alkylaminopropionic acid to basic amino acid is (0.5 to 2.0) to 1.

14. A personal care composition comprising the alkylaminopropionic acid salt of a basic amino acid of claim 1.

15. The personal care composition of claim 14 where the alkylaminopropionic acid is at least one of lauraminopropionic acid, cocaminopropionic acid, and stearaminopropionic acid.

16. The personal care composition of claim 14 comprising about between 0.01 and 50% by weight of the alkylaminopropionic acid salt of a basic amino acid of claim 1.

17. The personal care composition of claim 16 where the alkylaminopropionic acid is at least one of lauraminopropionic acid, cocaminopropionic acid, and stearaminopropionic acid.

18. The personal care composition of claim 14 where the basic amino acid is L-arginine.

19. A composition comprising at least one of a fire-fighting foam, a hard surface cleaner, a foaming acid cleaner, a basic cleaner, an additive to a textile finish, an antibacterial cleaner, and a foamer for lowering hydrostatic pressure in gas wells, the composition comprising the alkylaminopropionic acid salt of a basic amino acid of claim 1.

20. The composition of claim 19 where the alkylaminopropionic acid is at least one of lauraminopropionic acid, cocaminopropionic acid, and stearaminopropionic acid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The organization and manner of the structure and operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying non-scale drawings, wherein like reference numerals identify like elements in which:

[0017] FIG. 1 is a chart of wetting time at two different pH levels for the composition of the preferred embodiment of the present invention and several other common products.

[0018] FIG. 2 is a chart of the ZEIN number of the composition of the preferred embodiment of the present invention and several other products.

[0019] FIG. 3 is a chart of the level of the foam-water interface for the preferred embodiment of the present invention and several other products.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] It is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Unless indicated otherwise, all amounts of composition ingredients expressed in percentage terms are expressed as weight/weight.

[0021] It has been surprisingly discovered that arginine salts of alkylaminopropionic acids exhibit very low potential for skin irritation while demonstrating excellent surfactant properties and are thus ideal candidates for use in personal care and cosmetic formulations. According to the present invention, salts of alkylaminopropionic acids are provided which are represented by the formula (III).

##STR00003##

[0022] where R represents a linear or branched alkyl or alkenyl group having from 8 to 22 carbon atoms.

[0023] Examples of alkylaminopropionic acids include lauraminopropionic acid, cocaminopropionic acid, and stearaminopropionic acid. A preferred embodiment of the present invention uses lauraminopropionic acid.

[0024] According to the present invention, compounds containing arginine are provided. Arginine is a semi-essential amino acid. Typically, arginine is found in the L-form (commercially available from Ajinomoto). In an embodiment of the present invention the arginine is a natural or synthetic L-arginine.

[0025] When the alkylaminopropionic acid and the arginine are combined, the arginine neutralizes the alkylaminopropionic acid to form a surfactant. Thus, the subjects of the present invention include both an alkylaminopropionic acid and arginine in a combination that provides a salt of the two components.

[0026] Zein numbers provide a way of measuring the irritancy of a given compound. Zein numbers are measured by incubating solutions of a compound with solid Zein protein until saturated. Undissolved zein protein was then removed by centrifugation followed by filtration. The amount of zein that has been solubilized can then be measured by standard protein assay methods such as a Pierce BCA protein assay kit. Solubilization of higher amounts of Zein protein results in a higher Zein number, which is associated with greater amounts of irritation. Surprisingly, the arginine salts of the present invention were found to have very low Zein numbers.

[0027] Desirable surfactant properties include surface tension reduction, wetting, and foam generation. The compounds of the present invention demonstrate these surface active properties. In particular, it was surprisingly found that the wetting capacity of the inventive compounds was superior to that of other surfactant compounds commonly used in personal care products.

EXAMPLES

[0028] The following examples are intended to further illustrate the present invention. They are not intended to limit the invention in anyway.

Example 1

[0029] Preparation of Arginine Lauraminopropionate

[0030] Preparation A (2:1 Mole Ratio):

[0031] To 300 grams of an aqueous solution containing 100 grams (0.39 moles) of lauraminopropionic acid, were added 56 grams of water and 34 grams (0.195 moles) of arginine. The mixture was mixed at 60 C. until clear and homogeneous. The resulting solution was a pale yellow, clear liquid with a pH of 10.5 and a viscosity at 25 degrees C. of 1080 cps.

[0032] Preparation B (1:1 Mole Ratio)

[0033] To 300 grams of an aqueous solution containing 100 grams (0.39 moles) of lauraminopropionic acid, were added 158.4 grams of water and 67.9 grams (0.39 moles) of arginine. The mixture was mixed at 60 C. until clear and homogeneous. The resulting solution was a pale yellow, clear liquid with a pH of 9.9 and a viscosity at 25 degrees C. of 1250 cps.

[0034] Preparation C (2:3 Mole Ratio)

[0035] To 200 grams of an aqueous solution containing 55 grams (0.21 moles) of lauraminopropionic acid, were added 114 grams of water and 56 grams (0.32 moles) of arginine. The mixture was mixed at 40 C. until clear and homogeneous. The resulting solution was a pale yellow, clear liquid with a pH of 9.6 and a viscosity at 25 C. of 2849 cps.

Example 2

[0036] Surface Tension

[0037] Surface tension measurements were taken on solutions made from the mixture prepared in Example 1(C) using a du Nouy ring interfacial tensiometer, equipped with a six-cm circumference platinum-iridium ring. A series of test solutions at different concentrations were prepared and their surface tension measured at 25 C. For each test concentration, the ring is slowly drawn out of the liquid. The surface tension is equal to the force required to draw the ring completely out of the liquid, divided by twice the circumference of the ring. The Critical Micelle Concentration (CMC) was found to be 2.46 millimoles per liter. The surface tension at the CMC was 29.6 dyne/cm.

Example 3

[0038] Wetting

[0039] Surfactant wetting was measured according to the Draves cotton skein method on the arginine lauraminopropionate prepared in Example 1(C) and on several other commercially available surfactants commonly used in personal care products. Cotton skeins weighing 5.00.05 grams were attached to a lead weight and completely immersed in solutions containing 0.5% of each test surfactant at 25 C. The time required for the skein to sink was recorded. The results for two different pH levels are shown in FIG. 1.

Example 4

[0040] Zein Solubilization:

[0041] Solutions of the arginine lauraminopropionate prepared in Example 1(C) and on several other commercially available surfactants commonly used in personal care products were prepared at 10 mM in deionized water. To 100 mL of each solution, one gram of zein protein was added and incubated for one hour with mixing at 25 C. Undissolved protein was then removed by centrifugation followed by filtration through a 0.46 m membrane. The protein concentration of the filtrate was analyzed using a Pierce BCA protein assay kit and a Lange LICO 620 spectral-photometer at wavelength of 560 nm. The results are shown in FIG. 2.

Example 5

[0042] Foam Generation

[0043] Foam generation and drainage was evaluated on arginine lauraminopropionate prepared in Example 1(C) and on several other commercially available surfactants commonly used in personal care products using a blender foam test. Solutions of test surfactants were prepared at 10 mM in deionized water at 25 C. 100 mL of each solution was placed in a blender (Osterizer) and agitated at high speed for 10 seconds. The foam was poured into a 1000 mL graduated cylinder and the foam volume recorded. After five minutes, the level of the foam-water interface was recorded. The results are shown in FIG. 3.

[0044] The composition of the present invention can be used in a wide variety of products, such as a hydrotrope and foaming agent for fire-fighting foam, for a hard surface cleaner useful on, for examples, windows, floors, dishwashing, car washing, and for foaming acid and basic cleaners. The composition is also useful as an additive to textile finishes to aid in lubricity and then finish removal (scouring). The composition can be used as a foamer for antibacterial cleaners and as a foamer for lowering hydrostatic pressure in gas wells, particularly in the presence of high and low pH formulations.

[0045] The composition of the present invention, due to its amphoteric nature, possesses a good water solubility over a broad pH range (acidic to alkaline) even when high electrolyte concentration is present. Accordingly, the composition of the present invention can be used in a wide variety of products besides personal care products, for examples as a hydrotrope and foaming agent for fire-fighting foam, as a hard surface cleaner useful on, for examples, windows, floors, dishwashing, car washing, and for foaming acid and basic cleaners. The composition is also useful as an additive to textile finishes to aid in lubricity and then finish removal (scouring). The composition can be used as a foamer for antibacterial cleaners and as a foamer for lowering hydrostatic pressure in gas wells, particularly in the presence of high and low pH formulations.

[0046] While preferred embodiments of the present invention are shown and described, it is envisioned that those skilled in the art may devise various modifications of the present invention without departing from the scope of the appended claims.