BACKGROUND OF THE INVENTION
[Field of the Invention)
[0001] This invention relates to a detergent composition. More particularly, it relates
to a detergent composition which is suitable for washing the body including the hair
and the skin and comfortable in its use.
[Description of the Prior Art]
[0002] Body detergent compositions usually comprise common anionic surfactants. Namely,
soaps, i.e., higher fatty acid salts are mainly used for cleansing the skin while
alkyl sulfates or sulfonates are mainly used for shampooing the hair.
[0003] The soaps used for cleansing the skin are disadvantageous in that the soap scum (calcium
salts of higher fatty acids) formed during rinsing would adhere to the skin, which
seriously deteriorates the lubricity of the surface of the skin and causes coarseness
or tension. In order to improve this disadvantage, attempts have been made to develop
composite type detergents by blending an oily component such as a higher alcohol or
a humectant such as propylene glycol with the aforesaid soaps or by using an anionic
surfactant which never forms any scum.
[0004] However the addition of such an oily component in a small amount cannot give the
desired effect. On the other hand, the addition of a large amount thereof might cause
another problem that the foaming properties are substantially deteriorated. When such
an anionic surfactant forming no scum is used, the coarseness would decrease with
an increase in said component. When it is used in such an amount as to give a satisfactory
effect, however, the foam breaking is retarded and the detergent composition becomes
slimy.
[0005] On the other hand, the aforesaid alkyl sulfates and sulfonates used in shampoos form
no scum and thus never give such coarseness or tension as those observed when a soap
is used. However a detergent composition containing such components is poor in foam
breaking and cannot impart a lubricity to the hair. In order to improve these disadvantages,
there has been attempted to add oily components such as higher alcohols, hydrocarbons
or silicone. In this case, however, the addition of these oily components in a small
amount cannot give the desired effect and the addition of a large amount thereof would
substantially deteriorate the foaming properties of the detergent composition.
[0006] There have been known detergents comprising N-alkylacylamino acid surfactants. For
example, Japanese Patent Laid-Open No. 150701/1975 and Japanese Patent Laid-Open No.
2962/1988 disclose each a liquid detergent composition comprising an N-(long-chain
acyl)amino acid surfactant, which is a less irritative surfactant, as a base. Further,
Japanese Patent Laid-Open No. 132007/1978 discloses an improved solid detergent comprising
an N-(long-chain acyl)neutral amino acid.
[0007] Although the tertiary amide-type N-alkyl-N-acylamino acid salts employed in the detergent
compositions described in these references are highly soluble in water, they are poor
in foam breaking and the comfort in its use, namely, they are somewhat slimy. Japanese
Patent Laid-Open No. 2962/1988 further shows N-lauroyl-β-alanine sodium salt which
is a secondary amide type N-acylamino acid salt (refer to Example 5). However this
compound has a low solubility in water, which makes it unsuitable for a liquid detergent
composition. Furthermore, the addition of this compound at a concentration of 1% (as
specified in Table 1 in the aforesaid reference) cannot achieve a desirable comfort
in its use.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a detergent composition which
is highly soluble in water has good foaming properties during cleansing, shows a rapid
foam breaking during rinsing, gives no sliminess, imparts a high lubricity to the
surface of the material to be cleansed from the rinsing step to after the drying,
is less irritative, causes neither coarseness nor tension after the completion of
the use and is excellent in the comfort in its use.
[0009] The present inventors have conducted extensive studies and thus found out that the
aforesaid objects can be achieved by using a specific N-acyl compound as the main
base of a detergent composition.
[0010] Accordingly, the present invention, which has been completed based on the above finding,
provides a liquid detergent composition containing 5 to 60% by weight of a potassium
or alkanolamine salt of a secondary amide-type N-acylamino acid represented by the
following general formula (I), which will be referred to as the first invention hereinafter.
RCONH(CH₂)
nCOOH (I)
wherein R represents a straight-chain saturated hydrocarbon acyl group having 10
to 14 carbon atoms; and
n is a number of 2.
[0011] The present inventors have conducted further studies and thus found out that the
above objects can be achieved by using a specific N-acyl compound as the main base
of a detergent composition and combining said compound with other surfactant(s) at
a specific ratio.
[0012] The present invention, which has been completed based on the above finding, provides
a detergent composition comprising an N-acyl compound (A) represented by the following
general formula (II) and surfactant(s) [other than the component (A)] (B) at a weight
ratio of (A)/(B) of from 99/1 to 1/1, which will be referred to as the second invention
hereinafter.
RCONH(CH₂)
nCOOM (II)
wherein RCO represents a straight-chain acyl group having 8 to 22 carbon atoms;
n is an integer of from 1 to 11; and
M represents an alkali metal or an inorganic or organic ammonium.
[0013] Each of the liquid detergent composition and detergent composition of the present
invention is highly soluble in water, has good foaming properties during cleansing,
shows a rapid foam breaking during rinsing, gives no sliminess, imparts a high lubricity
to the surface of the material to be cleansed from the rinsing step to after the drying,
is less irritative, causes neither coarseness nor tension after the completion of
the use and is excellent in the comfort in its use. Thus it is particularly suitable
for cleansing the skin (body and face) or shampooing the hair.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Now the liquid detergent composition of the first invention will be described in
detail.
[0015] The potassium or alkanolamine salt of the N-acylamino acid represented by the above
general formula (I) (hereinafter also called the N-acyl compound), which is one of
the components of the detergent composition of the first invention, would react with
calcium in tap water to form highly lubricant platy crystals.
[0016] It is preferable that RCO in the above general formula (I) of the aforesaid N-acyl
compound is a straight-chain saturated hydrocarbon acyl group having 10 to 14 carbon
atoms, in particular, a lauroyl group having 12 carbon atoms. When the carbon atom
number thereof exceeds 14, the lubricity of the formed platy crystals and the foaming
properties of the composition are deteriorated. When the carbon atom number thereof
is less than 10, on the other hand, the foaming properties are deteriorated. Thus
both of these cases are undesirable.
[0017] The lubricity of the platy crystals formed by the reaction between the aforesaid
N-acyl compound and calcium may be determined by, for example, measuring the coefficient
of static friction of the platy crystals on dried pigskin (ALLOASK; a product of Kotai
Kasei Kogyo K.K.) which has been reconstituted with physiological saline. Namely,
platy crystals showing a coefficient of static friction lower than that of the blank
lot throughout the moisture-containing point to after the completion of the drying
are rated high.
[0018] It is very important that the aforesaid N-acyl compound has a secondary amide-type
structure wherein the N-acyl group consists of the above-mentioned straight-chain
acyl. When the acyl group constituting the N-acyl group is branched or the amide has
a tertiary amide type structure, the formation of the platy crystals is suppressed
or the formed crystals are poor in lubridity and thus sticky. In these cases, therefore,
a desirable texture can be hardly obtained.
[0019] The aforesaid N-acyl compound is a potassium (hereinafter sometimes abbreviated as
K) or an alkanolamine salt such as monoethanolamine, diethanolamine or triethanolamine
(hereinafter sometimes abbreviated as TEA) salt of an N-acylamino acid represented
by the above general formula (I). It is undesirable to use a sodium (hereinafter sometimes
abbreviated as Na) of the N-acylamino acid since it has a high Krafft point and a
low solubility in water and is therefore unsuitable for a liquid detergent.
[0020] The content of the aforesaid N-acyl compound may range from 5 to 60% by weight, preferably
from 20 to 50% by weight, based on the composition of the first invention. When the
content thereof is less than 5% by weight, the state of feeling refreshed and comfort
in its use due to the platy crystals formed during rinsing cannot be obtained. When
it exceeds 60% by weight, on the other hand, the liquid composition would set to gel
and thus a good liquid detergent composition cannot be obtained.
[0021] The aforesaid N-acyl compound (secondary amide-type N-acylamino acid salt) may be
produced by, for example, the following method. An amino acid is acylated by commonly
known Schotten-Baumann reaction wherein an alkali aqueous solution of the amino acid
and sodium hydroxide is reacted with a fatty acid chloride. Then the reaction mixture
is acidified by adding hydrochloric acid to thereby give an N-acylamino acid (acid
type). The obtained product is filtered, dried and then neutralized with potassium
hydroxide or an alkanolamine. Thus the secondary amide-type N-acylamino acid to be
used in the first invention can be obtained.
[0022] The liquid detergent composition of the first invention may be formulated into a
paste or a gel by adding a thickener or a binder, if required.
[0023] The liquid detergent composition of the first invention may further contain components
commonly employed in detergent compositions, for example, humectants, touch improvers,
viscosity modifiers, bactericides, perfumes or colorants, so long as the formation
of the highly lubricant platy crystals during the rinsing step is not inhibited thereby.
[0024] The pH value of the liquid detergent composition of the first invention may be 6
or above and preferably range from 7 to 10.
[0025] The liquid detergent composition of the first invention, which has been described
in detail above, is suitable for cleansing the body including the skin and the hair.
It is particularly suitable for cleansing the skin.
[0026] Now the detergent composition of the second invention will be described in detail.
[0027] The N-acyl compound represented by the above general formula (II), which is the component
(A) of the detergent composition of the second invention, would react with calcium
in tap water to form highly lubricant platy crystals, similar to the above-mentioned
N-acyl compound in the first invention.
[0028] It is preferable that RCO in the above general formula (II) of the aforesaid N-acyl
compound is a straight-chain acyl group having 8 to 22 carbon atoms, in particular,
a straight-chain acyl group having 10 to 14 carbon atoms such as a caprinoyl, lauroyl
or myristoyl group. When the carbon atom number thereof exceeds 22, the lubricity
of the formed platy crystals is deteriorated. When the carbon atom number thereof
is less than 8, on the other hand, the foaming properties are deteriorated. Thus both
of these cases are undesirable. Further, a is an integer of from 1 to 11, preferably
from 1 to 5 and still preferably 1 or 2, from the viewpoint of the lubricity of the
platy crystals.
[0029] The lubricity of the platy crystals formed by the reaction between the aforesaid
N-acyl compound and calcium may be determined and evaluated by the same method as
the above-mentioned one employed in the case of the N-acyl compound of the first invention.
[0030] It is very important that the aforesaid N-acyl compound has a secondary amide-type
structure wherein the N-acyl group consists of the above-mentioned straight-chain
acyl. When the acyl group constituting the N-acyl group is branched or the amide has
a tertiary amide type structure, the formation of the platy crystals is suppressed
or the formed crystals are poor in lubricity and thus sticky. In these cases, therefore,
a desirable texture can be hardly obtained.
[0031] As M constituting a counter ion in the above general formula (II) of the aforesaid
N-acyl compound, alkali metals such as sodium (hereinafter sometimes abbreviated as
Na) and potassium (hereinafter sometimes abbreviated as K) and inorganic or organic
ammonium may be cited. The organic ammonium includes acid salts of organic amine compounds
such as alkanolamines such as monoethanolamine, diethanolamine and triethanolamine
(hereinafter sometimes abbreviated as TEA), alkylamines and basic amino acids.
[0032] The content of the aforesaid N-acyl compound may be 5% by weight or above, preferably
from 20 to 80% by weight, based on the composition of the second invention. When the
content thereof is less than 5% by weight, the state of feeling refreshed and comfort
in its use due to the platy crystals formed during rinsing cannot be obtained.
[0033] As the surfactant which is the component (B) of the determent composition of the
second invention, various surfactants including the following ones may be used.
[0034] Examples of anionic surfactants include sulfate and sulfonate surfactants such as
alkyl sulfates and polyokyethylene alkyl sulfates and sulfosuccinic acid, taurate,
isethionate and α-olefinsulfonate surfactants; carboxylate surfactants such as fatty
acid soaps, fatty acid salts, ether carboxylic acid surfactants and acylated amino
acid surfactants; and phosphate ones such as alkyl phosphate surfactants. Among these
surfactants, fatty acid, phosphate and isethionate surfactants are particularly preferable
from the viewpoint of foaming properties.
[0035] Examples of ampholytic surfactants include carbobetaine, sulfobetaine and imidazoliniumbetaine
surfactants. It is preferable to use hydroxypropylsulfobetaine and desalted secondary
imidazoliniumbetaine.
[0036] Examples of nonionic surfactants include polyhydric alcohols such as polyoxyalkylene
addition type, polyoxypropylene/polyoxyethylene addition type, amine oxide and mono-
or diethanoloamide as well as sorbitan fatty acid esters, glycerol fatty acid esters,
sucrose fatty acid esters and alkyl saccharide and N-poylhydroxyalkyl fatty acid amide
surfactants. It is particularly preferable to use amine oxide, diethanolamide and
alkyl saccharide surfactants.
[0037] Examples of cationic surfactants include mono- or dialkyl-addition type quaternary
ammonium salts having a straight-chain or branched alkyl group and those obtained
by adding an alkylene oxide to the alkyl group thereof. It is particularly preferable
to use straight-chain monoalkyl quaternary ammonium salts having 12 to 16 carbon atoms
and quaternary ammonium salts having a branched alkyl group having 20 to 28 carbon
atoms.
[0038] Either one of these surfactants or a mixture thereof may be used depending on the
performance of the target product.
[0039] The content of the surfactant(s) may preferably range from 0.1 to 45% by weight based
on the composition of the second invention.
[0040] The detergent composition of the second invention may comprise the aforesaid N-acyl
compound, i.e., the component (A) and the aforesaid surfactant, i.e., the component
(B) at a weight ratio of (A)/(B) of from 99/1 to 1/1 (preferably from 95/5 to 60/40).
When the weight ratio does not fall within the range as specified above, a comfort
in its use due to the formed lubricant platy crystals can be hardly obtained.
[0041] The detergent composition of the second invention may be formulated into any form,
for example, liquid, paste, solid or powder, without restriction.
[0042] The detergent composition of the second invention may further contain various foaming
aids and foam improvers to improve the foaming and foam qualities, so long as the
formation of the highly lubricant platy crystals during the rinsing step is not inhibited
thereby.
[0043] The detergent composition of the second invention may further contain components
commonly employed in detergent compositions, for example, humectants, touch improvers,
viscosity modifiers, perfumes or colorants, so long as the effects of the present
invention are not deteriorated thereby.
[0044] It is needless to say that the amounts of the aforesaid foaming aids, foam improvers
and common additives may be appropriately varied depending on the form of the detergent
composition.
[0045] The pH value of the detergent composition of the second invention may be 6 or above
and preferably range from 7 to 10.
[0046] The detergent composition of the second invention, which has been described in detail
above, is suitable for cleansing the body including the skin and the hair, though
the application range thereof is not particularly limited.
[0047] To further illustrate the present invention, and not by way of limitation, the following
Examples will be given. Examples 1 to 4 show each an embodiment of the first invention,
whereas Examples 5 to 7 show each an embodiment of the second invention.
Example 1
[0048] Each liquid detergent composition of the formulation as specified in Table 1 was
prepared and the solubility, foaming properties, precipitation of platy crystals and
comfort in the use thereof were evaluated in accordance with the criteria as specified
below. Table 1 summarizes the results.
Evaluation of solubility
[0049] The appearance of each liquid detergent composition at 10°C was evaluated with the
naked eye in accordance with the criteria as specified below.
Criteria:
[0050]
- ○:
- transparent.
- X:
- turbid or a precipitate is observed due to the formation of crystals.
Evaluation of foaming properties
[0051] The foam volume was measured by the following method and thus the foaming properties
were evaluated in accordance with the criteria as specified below. Each liquid detergent
composition was diluted 10-fold with water. 100 ml of the aqueous solution (liquid
temperature: 20°C) thus obtained was poured into a volumetric cylinder. Next, stirring
blades were placed in the solution and the volume (ml) of the foam formed 30 seconds
after the initiation of stirring was measured. The value thus determined was referred
to as the foam volume. The stirring blades were rotated at 1,000 rpm and the rotation
was reversed every 5 seconds.
Criteria:
[0052]
- ⓞ:
- foam volume is 200 ml or above.
- ○:
- foam volume ranges from 150 to 200 ml.
- X:
- foam volume is less than 150 ml.
Evaluation of the precipitation of lubricant platy crystals
[0053] Each liquid detergent composition was diluted 10-fold with ion-exchanged water. 1
ml of the obtained aqueous solution was poured into 50 ml of 4° DH hard water at 20°C.
After 10 seconds, the formation of crystals was observed with the naked eye and thus
evaluated in accordance with the criteria as specified below.
Criteria:
[0054]
- ⓞ:
- crystals are formed and the solution becomes cloudy.
- △:
- crystals are formed and the solution becomes slightly cloudy.
- X:
- no crystal is formed and the solution remains transparent.
Evaluation of comfort in the use
[0055] Ten male panelists and 10 female ones washed their bodies with each liquid detergent
composition for a week and the comfort in the use of the product was organoleptically
evaluated. The results given in Table 1 were the averages of the data obtained in
accordance with the criteria as specified below.
Criteria:
[0056]
(1) Foam breaking during rinsing:
- 5:
- good.
- 4:
- somewhat good.
- 3:
- moderate.
- 2:
- somewhat poor.
- 1:
- poor.
(2) Slippage during rinsing;
(3) Slippage after rinsing; and
(4) Slippage after drying:
- 5:
- good.
- 4:
- somewhat good.
- 3:
- moderate.
- 2:
- somewhat poor.
- 1:
- poor.

Example 2
[0057] Regarding the secondary amide-type N-acylamino acid salts (K salts and TEA salts)
to be used in the liquid detergent compositions of the first invention, the solubility,
formation of lubricant platy crystals and comfort in the use were evaluated in accordance
with the criteria as specified below. For comparison, secondary amide-type N-acylamino
acid Na salts and tertiary amide-type N-alkyl-N-acylamino acid salts were evaluated
in the same manner. Table 2 shows the results and the Krafft points of these amino
acid salts.
Evaluation of solubility
[0058] A 5% by weight aqueous solution of each amino acid salt was prepared and the solubility
of the solution thus obtained at 10°C was evaluated in accordance with the criteria
as specified below.
Criteria:
[0059]
- ○:
- soluble.
- X:
- insoluble (precipitation of crystals).
Evaluation of the formation of lubricant platy crystals
[0060] A 5% by weight aqueous solution of each amino acid salt was prepared and 1 ml of
the obtained solution was poured into 50 ml of 4°DH hard water at 20°C. After 10 seconds,
the formation of crystals was determined and evaluated in accordance with the criteria
as specified below.
Criteria:
[0061]
- ○:
- crystals are formed.
- X:
- no crystal is formed.
Evaluation of comfort in the use
[0062] A 5% by weight aqueous solution of each amino acid salt was prepared and a subject
washed the body with the obtained solution. Then the slippage from the rinsing step
to after drying was evaluated in accordance with the criteria as specified below.
Criteria:
[0063]
- ⓞ:
- very good.
- ○:
- good.
- X:
- poor.

Example 3
[0064]

[0065] In accordance with the above formulation, the component (1) was dissolved in hot
water. After cooling, the components (2) to (4) were added thereto. Thus a transparent
liquid detergent composition was prepared.
[0066] When the skin and the hair were washed with the liquid detergent composition obtained
above, the product showed good foaming properties, good foam breaking, good slippage
from the rinsing step to after drying and an excellent comfort in the use.
Example 4
[0067]

[0068] In accordance with the above formulation, the component (2) was added to hot water
followed by the addition of the component (1), and the components were neutralized
and dissolved. After cooling, the components (3) to (5) were added thereto. Thus a
transparent liquid detergent composition was prepared.
[0069] When the skin and the hair were washed with the liquid detergent composition obtained
above, the product showed good foaming properties, good foam breaking, good slippage
from the rinsing step to after drying and an excellent comfort in the use.
Example 5
[0070] Detergent compositions of the formulations as specified in Table 3 were prepared.
The foam volume of each detergent composition was determined by the following method.
Further, the formation of lubricant platy crystals and the comfort in the use thereof
were evaluated in accordance with the criteria as specified below. Tables 3 and 4
show the results. The detergent compositions No. 27 to No. 33 are comparative products.
Determination of foam volume
[0071] Each detergent composition was diluted 20-fold with water. 100 ml of the aqueous
solution (liquid temperature: 40°C) thus obtained was poured into a volumetric cylinder.
Next, stirring blades were placed in the solution and the volume (ml) of the foam
formed 30 seconds after the initiation of stirring was measured. The value thus determined
was referred to as the foam volume. The stirring blades were rotated at 1,000 rpm
and the rotation was reversed every 5 seconds.
Evaluation of the precipitation of lubricant platy crystals
[0072] Each liquid detergent composition was diluted 20-fold with ion-exchanged water. 1
ml of the obtained aqueous solution was poured into 40 ml of 4° DH hard water at 40°C.
After 10 seconds, the formation of crystals was observed with the naked eye aid thus
observed in accordance with the criteria as specified below.
Criteria:
[0073]
- ○:
- crystals are formed and the solution becomes cloudy.
- △:
- crystals are formed and the solution becomes slightly cloudy.
- X:
- no crystal is formed and the solution remains transparent.
Evaluation of comfort in the use
[0074] Ten male panelists and 10 female ones washed their skins with all of the aforesaid
detergent compositions and their hairs with some of the detergent compositions and
the comfort in the use of each product was organoleptically evaluated. The averages
of the data obtained in accordance with the criteria as specified below were calculated
and referred to as very good (ⓞ; ≧ 4.5), good (○; from 3.5 to 4-4), moderate (△; from
2.5 to 3.4) and poor (X: ≦ 2.4).
Criteria:
[0075]
(1) Foam breaking during rinsing:
- 5:
- good.
- 4:
- somewhat good.
- 3:
- moderate.
- 2:
- somewhat poor.
- 1:
- poor.
(2) Slippage during rinsing;
(3) Slippage after rinsing; and
(4) Slippage after drying:
- 5:
- good.
- 4:
- somewhat good.
- 3:
- moderate.
- 2:
- somewhat poor.
- 1:
- poor.

Example 6
[0076]

[0077] In accordance with the above formulation, the components (1) to (3) were dissolved
in hot water. After cooling, the components (4) and (5) were added thereto. Thus a
liquid detergent composition was prepared.
[0078] When the skin and the hair were washed with the liquid detergent composition obtained
above, the product showed good foaming properties, good foam breaking, good slippage
from the rinsing step to after drying and an excellent comfort in the use.
Example 7
[0079]

[0080] In accordance with the above formulation, the components (1) to (3) were dissolved
in hot water. After cooling, the components (4) to (6) were added thereto. Thus a
liquid detergent composition was prepared.
[0081] When the skin and the hair were washed with the liquid detergent composition obtained
above, the product showed good foaming properties, good foam breaking, good slippage
from the rinsing step to after drying and an excellent comfort in the use.
Example 8
[0082]

[0083] In accordance with the above formation, the components (1) to (5) were mixed uniformly
at 60°C. After cooling, the obtained mixture was subjected to kneading, extrusion
and stamping in the conventional manner. Thus a solid detergent composition was prepared.
[0084] When the skin and the hair were washed with the solid detergent composition obtained
above, the product showed good foaming properties, good foam breaking, good slippage
from the rinsing step to after drying and an excellent comfort in the use.
Test Example 1
[0085] 5 ml of each sample in Table 5 contained in a glass of 3 cm in diameter was applied
to the forearms of 10 subjects for 30 minutes and after the treatment the test parts
were rinsed with tap water and wiped with a towel. This procedure was conducted twice
a day for 4 days (i.e., 8 times in total). On the fifth day, the rash conditions (erythema
and desquamation) of the test parts were evaluated with the naked eye in accordance
with the criteria as specified below by skilled persons. Table 5 shows the results
on average.
Criteria:
[0086]
(1) Erythema
- 0:
- nonobservable.
- 0.5:
- slightly observed.
- 1:
- somewhat observed.
- 2:
- observed.
- 3:
- extremely observed.
(2) Desquamation
- 0:
- nonobservable.
- 0.5:
- slightly observed
- 1:
- somewhat observed.
- 2:
- observed.
- 3:
- extremely observed.
