JPS6033158B2 - liquid cleaning composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a weakly acidic liquid detergent composition that has excellent foaming properties, mild action on the skin, and excellent liquid transparency.

Recently, many cosmetics have been adjusted to have mild and natural effects on the skin and hair.

For example, the pH of shampoo is adjusted to 5 to 6, close to the pH of human skin, so that it has a milder effect on hair and skin. Recently, creams such as skin creams, hand creams, and hair creams have also been released that are adjusted to be slightly acidic. Reflecting the demands of the times, pH-adjusted products such as shampoos and facial soaps have been appearing one after another, and products that have a performance different from conventional surfactants have also appeared.

Conventionally, in light-duty synthetic detergents, sodium alkylbenzene sulfonates, higher alcohol sulfate ester triethanolamine salts, sodium POIJ oxyethylene alkyl ether sulfates, etc. have been used as main activators, but these synthetic detergents has skin irritation, and its improvement is strongly desired.

In addition, when using these surfactants in shampoo, the cleaning power is strong, so the hair does not lose its smoothness after washing.
It also has some drawbacks, such as being dry. As described above, anionic surfactants generally have a strong effect on the skin, while nonionic surfactants tend to have a weak effect.

The term "skin irritation" as used herein refers to dry flaky changes primarily in the stratum corneum of the skin, and is different from skin irritation, which refers to inflammatory changes such as redness. Nonionic surfactants such as glycerin higher fatty acid ester, polyoxyethylene alkyl phenol, polyoxyethylene alkyl ether,
Examples include sucrose higher fatty acid ester and sorbitan higher fatty acid ester, but although they are hypoallergenic, they do not foam well and do not meet the requirements for shampoos, facial soaps, and kitchen detergents.

Recently, acylated amino acids have been developed as active agents that improve the problem of poor foaming and are less irritating, and are attracting interest. For example, N-acyl sarcosinate, which is an acylated product of sarcosine (methylglycine), a type of amino acid, N-acyl-N-methyl-B-alaninate, which is an acylated product of N-methyl-8-alanine, and acylated product of glutamic acid. There are certain acylated glutamates. However, these active agents have poor solubility when used alone, and in weakly acidic conditions, N-acyl sarcosinate, N
-Methyl-B-alaninate forms a white precipitate and foaming is also reduced. In addition, JP-A No. 48-90982 uses a condensate of maleic anhydride and an alkylamine as a surfactant, and due to its excellent surfactant ability, it has excellent foaming power and cleaning power, and is resistant to E. coli and pyogenic pathogens. However, it is said that it exhibits antibacterial effects.

However, such monocarboxylate type surfactants are N-acylsarcosinate, N-acyl-N-methyl-
Similar to 8-alaninate, when it is weakly acidic, the solubility decreases, making it difficult to apply it to a transparent liquid detergent, and the foaming also decreases. Weakly acidic here refers to the pH of the skin, which is around pH 5 to 6, and has a mild effect on the skin, while weakly alkaline, which has a pH of 8 to 9, has the disadvantage that the skin becomes sticky after washing hair or face. . It was extremely difficult to develop a surfactant that is mild to the skin, has excellent foaming properties, and has excellent solubility even in the slightly acidic pH range, but we have synthesized various surfactants. As a result of investigation, it was discovered that mono-N-alkyl citric acid amide exhibits very unique behavior. In other words, it foamed more than conventional sulfonic acid type surfactants even in mildly acidic conditions, was extremely mild to the skin, had good solubility, and met all the requirements for a transparent cleanser. . In addition, the mildness to the skin is particularly excellent at pH 5 to 7, but it is slightly inferior at weak alkalinity exceeding pH 7. Also pH
If it is less than 5, even mono-N-alkyl citric acid amide becomes cloudy and its solubility deteriorates. An object of the present invention is to provide a liquid detergent composition that has excellent foaming properties, has a mild action on the skin layer, and has good solubility.

According to the present invention, the general formula (where RI represents a saturated or unsaturated hydrocarbon group having 10 to 16 carbon atoms, R2 represents a saturated or unsaturated hydrocarbon group having 10 to 16 carbon atoms or hydrogen, and M represents Indicates an alkali metal ion, ammonium ion, alkanol amine ion, lower aliphatic amine ion, or hydrogen.

) A liquid detergent composition containing a mono-N-alkyl citric acid amide represented by the following formula and having a pH of 5 to 7 is provided. Mono-N-alkylcitric acid amide, which is an essential component in the present invention, can be synthesized by a known method.

Specifically, mono N-alkyl citric acid amide is usually synthesized by a dehydration reaction between an amine and citric acid. As the amine used here, primary and secondary amines having active hydrogen can be used, and tertiary amines are not used. In the case of a secondary amine, the citric acid amide produced can be neutralized and used by dehydrating the amine and citric acid as shown in reaction formula '1) and (2) below. In the case of a primary amine, it is usually obtained by hydrolyzing and neutralizing imine obtained by complete dehydration condensation of amine and citric acid, as shown in the following reaction formulas '3' and '4i. By appropriately selecting the alkyl chain length of the amine, it is possible to obtain a surfactant suitable for the purpose. The total alkyl chain length of the amine is preferably 10 to 16, since the water solubility is poor in the range of 7 to 7, and the performance as a surfactant deteriorates if the total alkyl chain length is less than 10.

Therefore, the amines that are practically used include primary amines introduced from fats and oils such as laurylamine, myristylamine, and glumitylamine, and decyl, dodecyl, tridecyl, tetradecyl, hexadecyl, etc. starting from synthetic alcohols. Primary amines or secondary amines such as laurylmethylamine, myristylmethylamine, decylmethylamine, dihexylamine, diheptylamine, and dioctylamine can be used. The irritation of synthetic detergents to the skin has been studied in various ways, and various factors have been considered to cause skin irritation, such as the level of degreasing power, adsorption to the skin, the ability to penetrate subcutaneous tissue, and the denaturing effect of skin proteins. It will be done. Among these, it has been elucidated that there is a particularly strong correlation between the denaturing effects of skin proteins and skin irritation.
The inventors focused on this point and used bovine serum albumin (BS
A) was studied as a skin model protein, and the protein denaturing effects of various active agents were measured by measuring the CD spectrum. As a result, it was found that sulfuric acid ester and sulfonic acid type surfactants caused the greatest modification, followed by monocarboxylate type surfactants. This result is thought to be due to the anionic active agent reacting ionically to a partial cationic site of the protein, thereby denaturing the Q-helix structure of the protein. The citric acid monoamide used in the present invention is a dicarboxylate salt, and in a weakly acidic solution with a pH of 4 to 7, it exists in the form of a monosodium salt, has weak anionic properties, and does not react with proteins due to steric hindrance of the citric acid moiety. Since the amount is small, it is thought that there is almost no degeneration. In addition to the above-mentioned essential ingredients, the composition of the present invention includes anionic, cationic, nonionic, and amphoteric surfactants that are usually added to shampoos, facial soaps, and kitchen detergents;
Antioxidants such as HT and Q-tocopherol; UV absorbers such as 2-hydroxy-4-toxybenzophenone; organic chelating agents such as EDTA, citric acid, and malic acid; Bacterial agents: Thickeners such as coconut oil diethanolamide, polyethylene glycol distearate, etc. can be incorporated within the range that does not affect the objectives and effects of the present invention. Next, the present invention will be explained in more detail based on the following examples.

Prior to that, an overview of the test methods and evaluation methods employed in the experimental examples will be explained. - Skin irritation was evaluated using methods [1] and (2) below.

m A 1% aqueous solution of liquid detergent composition (3
500), the dipping-drying operation was performed 15 times at 1-minute intervals using a manual dipping test, and after 2 hours, the skin was visually evaluated to determine the degree of skin roughness.

○: Almost no skin roughness △: Some dry flaky changes in the stratum corneum surface layer of the skin ×: Dry flaky changes in more than 30% ■ Skin irritation Skin irritation was evaluated using the molecular ellipticity of bovine serum albumin ( The molecular ellipticity (already A molecular ellipticity) was used as an indicator and was measured by the following method.

Mother A molecular ellipticity measurement method After mixing each sample solution with 100 ppm of bovine serum albumin,
Add sodium phosphate buffer to 5 hM,
JASCOCD Spectrop-ela at 5℃
Circular dichroism was measured at r to determine the molecular ellipticity (hi).

By the way, the molecular ellipticity of degenerated bovine serum albumin is -11.3×1pideg. It was earth/decimcl.
(The numerical unit in the table is -[8]×10-6)
It has been confirmed that the molecular ellipticity is equivalent to that of bovine serum albumin, and that it does not show denaturation and causes almost no skin irritation.

A 15% aqueous solution of a transparent liquid cleaning composition was prepared and visually evaluated.

○: Good, ×: Poor 6% aqueous solution of foaming power-adjusted liquid detergent composition 20 [(2
Collect 5 pieces (○) in 100 [cylinders, add 0.2 hours of liquid lanolin as an artificial stain, and pour 20
After shaking and overflowing, the foam volume (k') was measured 1 minute later.

Conditioning properties Determined by comprehensive evaluation of static friction coefficient and hair smoothness.

'1} Static friction coefficient Mao Dong (5 days.20 skin) was massaged for 1 minute using the test liquid detergent composition 1.0 days, and after rinsing, 25oo, 6 days
Leave it in a constant temperature room at 5% RH for 2 hours to dry.

After drying, the static friction coefficient of the hair is measured using a friction coefficient meter (manufactured by Memoto Rheology Instruments Co., Ltd.). In addition, from a comparison with the smoothness of hair according to a sensory test, it has been found that when the coefficient of static friction is 0.17 or less, the smoothness of the hair is excellent. {2} Hair smoothness is evaluated by sensory test.

That is, Mao Dong (after washing, rinsing and drying)
The smoothness of the skin was evaluated by 20 testers using the paired comparison method using sodium dodecyl sulfate (SDS) as a control sample. Evaluation criteria +: Evaluation product is superior to SDS.

Ten: 〃 Somewhat ”.

〃 Equivalent.

Test Example 1 Nine types of liquid cleaning compositions having the compositions shown in Table 1 below were prepared and tested for performance.

The results are shown in the same table. In addition, the compounding amount is weight% (
The same applies to other test examples), and *1 to *9 indicate the following substances. *1: Sodium linear alkylbenzene sulfonate (molecular weight 346) *2: Sodium coconut oil alcohol sulfate (molecular weight 305) *3: Sodium polyoxyethylene alkyl ether sulfate (average number of moles of EO added: P= 3, alkyl group (R): C, 2/C, 3=1
/1) *4: *5: *6: *7: *8: *9: Table 1 As is clear from Table 1, the liquid cleaning composition of the present invention (Example 1) received four evaluations. In contrast, all of Comparative Examples 1 to 8 fail to satisfy at least one evaluation criterion.

Test Example 2 Seven types of liquid cleaning compositions having the compositions shown in Table 2 below were prepared and their performance was tested.

As is clear from the same table, in Comparative Examples 9 and 10, the carbon number of R in the mono-N-alkyl citric acid amide used was outside the range of the present invention, so the foaming power value was lower than that of the present invention (Example). 4. compared to 2-6). Table-2 Test examples
3 Eight types of shampoo compositions having the compositions shown in Table 3 below were prepared and tested for performance.

In the same table, *10 to *11 indicate the following substances.
*10: *11: Table 3 As is clear from Table 3, Comparative Examples 15 and 16 each contain the mono N-alkyl quinic acid amide of the present invention, but when the pH value of the liquid is between 5 and 7. The evaluation criteria cannot be satisfied because it is outside the range.

Comparative Examples 12 and 13 have pH values within the range of the present invention, but do not contain the above-mentioned essential components of the present invention, and therefore cannot satisfy the evaluation criteria. Test Example 4 A facial cleansing soap composition shown in Table 4 below was prepared and its performance was evaluated.

Note that this composition was adjusted to pH 5 with citric acid.
*12: *13: E○ (ethylene oxide) 20 mole adduct of lauryl alcohol *14: Sodium pyrrolidone carboxylate *15: Disodium ethylenediaminetetraacetate The above composition has excellent foaming properties, has a mild effect on the skin, and The transparency of the liquid was excellent.

Test Example 5 Conditioning shampoo compositions shown in Table 5 below were prepared and their performance was evaluated.

This composition was adjusted to pH 5 with citric acid. Table -
The composition shown in Table 5 showed the same excellent performance as Test Example 4.

Test Example 6 Kitchen detergent compositions shown in Table 6 below were prepared and their performance was evaluated.

This composition was adjusted to pH 6 with citric acid. Table 16 *16: R is C, 2nd day 25/C, 4th day 29=1/1.

*17: Sodium polyoxyethylene alkyl ether sulfate (average number of EO added moles: P = 3, R: C, 2/C
, 5=1/1) The composition in Table 6 showed superior performance to Test Example 4 and the same machine.

Claims (1)

[Claims] 1 General formula ▲ Numerical formulas, chemical formulas, tables, etc. 16 saturated or unsaturated hydrocarbon group or hydrogen, M represents an alkali metal ion, ammonium ion, alkanolamine ion, lower aliphatic amine ion, or hydrogen.) Mono-N-alkyl citric acid amide represented by A liquid cleaning composition having a pH of 5 to 7.