Aqueous liquid detergents containing an N-acyl-aspartate, amine oxide and alkyl ether sulfate

A liquid detergent composition is disclosed, containing (a) an N-acylaspartic acid or a salt thereof, (b) a tertiary alkylamine oxide and (c) an alkyl ether sulfate, the weight composition of the components (a), (b), and (c) falling within the range indicated by a quadrate formed by four points (90,5,5), (75,20,5), (50,20,30), and (65,5,30) in a triangular coordinate constructed by placing the pure components (a), (b), and (c) at the vertices of a regular triangle. The composition exhibits excellent foamability and detergency while retaining mildness to the skin and substantial fluidity.

FIELD OF THE INVENTION 
This invention relates to a novel three-component system detergent 
composition. More particularly, it relates to a liquid detergent 
composition containing an N-acylaspartic acid or a salt thereof as an 
amino acid-series anionic surface active agent, a tertiary alkylamine 
oxide as an amphoteric surface active agent, and an alkyl ether sulfate, 
which is excellent in foamability, detergency, and mildness to the skin. 
BACKGROUND OF THE INVENTION 
Anionic surface active agents, such as alkylbenzenesulfonates, have widely 
been used as main components in dishwashing detergents. From the viewpoint 
of irritation to the skin, the tendency now is turning toward mild 
detergents containing alkyl ether sulfates and amphoteric surface active 
agents as main components. However, alkyl ether sulfates are still 
unsatisfactory in mildness to the skin, and further improvements have been 
demanded. 
It has been proposed to incorporate an N-acylamino acid salt which is not 
only mild to the skin but effective to inhibit growth of harmful 
microorganisms causing skin diseases as disclosed in JP-B-46-4256 and 
JP-B-39-29444 (the term "JP-B" as used herein means an "examined Japanese 
patent publication"). However, an aqueous solution of the N-acylamino acid 
salt per se has low detergent action and it lacks detergency and 
foamability for cleaning off extremely oily dirt, for example, dishes or 
hair applied with pomade. 
JP-A-48-5904 (the term "JP-A" as used herein means an "unexamined published 
Japanese patent application") discloses use of an N-aclyglutamate in 
combination with a tertiary alkylamine oxide to thereby improve detergency 
and foamability without impairing mildness to the skin. However, it has 
been proved by the inventor's investigations that the tertiary alkylamine 
oxide must be used in an amount of at least 2/3 as much as the weight of 
the N-acylglutamate before one can obtain improved detergency and 
foamability and that incorporation of the tertiary alkylamine oxide in 
such a high ratio causes gelation and substantial loss of fluidity. 
SUMMARY OF THE INVENTION 
One object of this invention is to provide a liquid detergent composition 
exhibiting excellent foamability and detergency while retaining mildness 
to the skin and fluidity. 
As a result of extensive investigations, the inventor has found that 
incorporation of an alkyl ether sulfate into a detergent containing an 
N-acylaspartic acid or a salt thereof and a tertiary alkylamine oxide 
brings about improvements on foamability and detergency while retaining 
mildness to the skin and substantial fluidity. 
That is, the present invention relates to a liquid detergent composition 
containing (a) an N-acylaspartic acid or a salt thereof represented by 
formula (I): 
##STR1## 
wherein R represents an alkyl or alkenyl group having from 7 to 21 carbon 
atoms; and M.sub.1 and M.sub.2 each represents a hydrogen atom or a cation 
derived from Na, K, NH.sub.4 or an alkanolamine, (b) a tertiary alkylamine 
oxide represented by formula (II): 
##STR2## 
wherein R.sub.1 represents an alkyl or alkenyl group having from 10 to 18 
carbon atoms; and R.sub.2 and R.sub.3 each represents an alkyl group 
having from 1 to 3 carbon atoms, and (c) an alkyl ether sulfate 
represented by formula (III): 
##STR3## 
wherein R.sub.4 represents an alkyl or alkenyl group having from 7 to 20 
carbon atoms; p represents an average number of moles of ethylene oxide 
added and is selected from an integer of from 1 to 5; and M.sub.3 
represents a cation derived from Na, K, NH.sub.4 or an alkanolamine, the 
weight composition of the components (a), (b), and (c) falling within the 
range indicated by a quadrate formed by four points (90,5,5), (75,20,5), 
(50,20,30), and (65,5,30) in a triangular coordinate constructed by 
placing the pure components (a), (b), and (c) at the vertices of a regular 
triangle.

DETAILED DESCRIPTION OF THE INVENTION 
The N-acylaspartic acid or a salt thereof represented by formula (I) which 
can be used in the detergent composition of the present invention includes 
an L-form, a D-form, and a mixture thereof. 
Specific examples of the N-acylaspartic acid or a salt thereof which can 
suitably be used are N-lauroylaspartic acid, N-myristoylaspartic acid, 
N-palmitoylaspartic acid, N-stearoylaspartic acid, and N-oleoylaspartic 
acid, and their salts, e.g., sodium salts, potassium salts, 
monoethanolammonium salts, and triethanolammonium salts. 
The tertiary alkylamine oxide which can be used in the detergent 
composition of the present invention can be obtained, for example, by 
oxidizing a straight chain or branched long-chain alkyl tertiary amine 
with an oxidizing agent, such as hydrogen peroxide and Caro's acid. 
Examples of suitable tertiary alkylamine oxides are lauryldimethylamine 
oxide, myristyldimethylamine oxide, cetyldimethylamine oxide, 
lauryl-2-hydroxyethylamine oxide, laurylmethylethylamine oxide, 
lauryldiethylamine oxide, myristyldiethylamine oxide, oleyldimethylamine 
oxide, oleyldiethylamine oxide, myristylethylpropylamine oxide, 
lauryldipropylamine oxide, myristyldipropylamine oxide, cetyldipropylamine 
oxide, cetylmethylpropylamine oxide, and cocoalkyldimethylamine oxide. 
The alkyl ether sulfate which can be used in the present invention is a 
sodium, potassium, ammonium or alkanolamine salt of a sulfuric ester 
obtained by sulfation of an ethylene oxide adduct of a synthetic or 
naturally-occurring alcohol having from 7 to 20 carbon atoms, for example, 
with SO.sub.3 or chlorosulfonic acid. A specific example of suitable alkyl 
ether sulfates is the one which is prepared by sulfating an alcohol 
ethoxylate obtained by addition reaction between 1 mol of "Dobanol 23" (a 
product of Mitsubishi Petrochemical Co., Ltd.) and 3 mols of ethylene 
oxide with SO.sub.3 gas by means of a falling film type sulfation 
apparatus and then neutralizing with a sodium hydroxide aqueous solution. 
In the liquid detergent composition according to the present invention, the 
weight composition of (a) the N-acylaspartic acid or a salt thereof, (b) 
the tertiary alkylamine oxide, and (c) the alkyl ether sulfate should be 
within a range surrounded by a quadrate formed by lines connecting four 
points (90,5,5), (75,20,5), (50,20,30), and (65,5,30) in a triangular 
coordinate constructed by placing the pure components (a), (b), and (c) at 
the vertices of a regular triangle. 
If desired, the detergent composition of this invention may further contain 
other known components commonly employed in liquid detergent compositions, 
such as amphoteric surface active agents and nonionic surface active 
agents in amounts that do not impair the effects of the present invention, 
and commonly employed additives, such as viscosity-controlling agents, 
e.g., glycerin, propylene glycol, and inorganic salts; flavors, dyes, 
ultraviolet absorbents, and antioxidants. 
The liquid detergent composition according to the present invention is mild 
to the skin and exhibits excellent foamability and detergency. 
The present invention is now illustrated in greater detail by way of the 
following Examples, but it should be understood that the present invention 
is not deemed to be limited thereto. 
EXAMPLES 1 TO 10 
Sodium N-lauroyl-L-aspartate, lauryldimethylamine oxide, and sodium Dobanol 
23 (3E.phi.) sulfate obtained by sulfation of an ethylene oxide (3 mol) 
adduct of an aliphatic alcohol having 12 and 13 carbon atoms ("Dobanol 
23") were mixed with water to prepare a liquid detergent composition 
having a concentration of each component as shown in Table 1, with the 
total concentration of these three active components being 20% by weight. 
The resulting detergent composition was evaluated for foamability, 
detergency, and viscosity according to the following test methods. The 
results obtained are shown in table 1. 
(1) Foamability 
The detergent composition was 200-fold diluted with distilled water. A 20 
ml portion of the thus diluted detergent was put in a 100 ml-volume 
measuring cylinder with a ground-glass stopper together with 1 g of 
triolein as an oil component. The cylinder was stoppered and given 20 
vertical sharp shakings. Immediately after the shaking, the cylinder was 
placed horizontally, and the volume of the foam was read out. 
(2) Detergency 
Slide glass was dipped in a model dirt having the following composition for 
1 to 2 seconds and then air-dried. The slide glass having adhered thereto 
the dirt was washed with the liquid detergent composition 200-fold diluted 
with distilled water (content of surface active agent: 0.1% by weight) at 
25.degree. C. for 3 minutes under rotation of 250 rpm and then rinsed with 
distilled water at 25.degree. C. for 1 minute by means of a Leenerts 
improved detergency testing machine. The slide glass was air-dried, and 
the residual oil was determined. A detergency (%) can be calculated from 
equation: 
##EQU1## 
wherein Ws is the amount of the deposited oily dirt before washing; and Ws 
is the amount of the oily dirt remaining after washing. 
Composition of Model Dirt 
______________________________________ 
Soybean oil (JP) 10 g 
Beef tallow (JP) 10 g 
Monoolein 0.25 g 
Oil Red 0.1 g 
Chloroform 60 ml 
______________________________________ 
(3) Viscosity 
A viscosity of the detergent composition at 25.degree. C. was determined at 
a shear rate 1 (S.sup.-1) by the use of a corn/plate type rotation 
viscometer ("EHD, EMO, ELD" manufactured by Toki Sangyo K. K.). 
COMATIVE EXAMPLES 1 TO 10 
A liquid detergent composition having a composition shown in Table 2 was 
prepared. The properties of the resulting detergent composition were 
evaluated in the same manner as in Examples. In cases where the 
composition became a slurry or a gel, the viscosity was not determined, 
and only the appearance was observed. The results obtained are shown in 
Table 2. 
COMATIVE EXAMPLES 11 TO 16 
A liquid detergent composition having a composition shown in Table 3 was 
prepared. The properties of the resulting detergent composition were 
evaluated in the same manner as in Examples, and the results obtained are 
shown in Table 3. 
TABLE 1 
__________________________________________________________________________ 
Example No. 
1 2 3 4 5 6 7 8 9 10 
__________________________________________________________________________ 
Composition (wt %): 
Sodium N-lauroylaspartate 
18 17 15 13 12 10 12 14 15 14 
Lauryldimethylamine oxide 
1 1 1 1 2 4 4 4 4 2 
Sodium Dobanol 23(3E.phi.) sulfate 
1 2 4 6 6 6 4 2 1 4 
Performance Properties: 
Foamability (ml) 
80 75 70 65 80 85 90 85 80 75 
Detergency (%) 80 78 75 70 82 85 87 90 90 85 
Viscosity (cp) 200 
320 
400 
430 
450 
700 
650 
600 
550 
500 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
Comparative Example No. 
1 2 3 4 5 6 7 8 9 10 
__________________________________________________________________________ 
Composition (wt %): 
Sodium N-lauroylaspartate 
20 -- 
-- 
10 10 -- 8 12 10 8 
Lauryldimethylamine oxide 
-- 20 
-- 
10 -- 10 6 6 2 4 
Sodium Dobanol 23(3E.phi.) 
-- -- 
20 
-- 10 10 6 2 8 8 
sulfate 
Performance Properties: 
Foamability (ml) 
20 10 
60 
30 30 80 85 85 80 70 
Detergency (%) 
30 20 
40 
35 32 75 80 80 75 65 
Viscosity (cp) 
slurry 
10 
10 
clear 
slurry 
clear 
35000 
20000 
2000 
3500 
gel gel 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
Comparative Example No. 
1 2 3 4 5 6 
__________________________________________________________________________ 
Composition (wt %): 
Sodium N-lauroylglutamate 
18 12 10 12 15 14 
Lauryldimethylamine oxide 
1 2 4 4 4 2 
Sodium Dobanol 23(3E.phi.) sulfate 
1 6 6 4 1 4 
Performance Properties: 
Foamability (ml) 
50 60 70 65 60 65 
Detergency (%) 40 50 55 50 45 50 
Viscosity (cp) 180 
350 550 
600 500 
350 
__________________________________________________________________________ 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.