Note: Descriptions are shown in the official language in which they were submitted.
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FAF3RIC SOFTENING COMPOSITION
Field of the Invention
The present invention relates to a fabric softening
composition, in particular the invention relates to aqueous
dispersions of fabric softening compositions comprising a
water insoluble quaternary ammonium material and a nonionic
stabilising agent suitable as rinse-added fabric softener
compositions.
Backaround of the Invention
Rinse added fabric softeners are known. Typically such
compositions contain a water insoluble quaternary ammonium
fabric softening agent dispersed in water at a level of
softening agent up to about 7 wt%, in which case the
compositions are considered dilute, or at levels from 7 wt%
to 50 wt%, in which case the compositions are known as
concentrates.
The viscosity of fabric softener may be seen by the consumer
as an important attribute. For this reason thickening
polymers are added to compositions, for example EP 0 331 237
(Unilever) discloses the use of hydrophobically modified
nonionic cellulose ether for use as a thickener for fabric
conditioning compositions containing quaternary ammonium
cations.
There are however negative attributes associated with many
polymeric thickeners in that they are not biodegradable,
their addition to the rinse product is technically difficult
and the viscosity of such polymer thickened products tends to
increase with time.
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In US 4 137 180 (Lever Brothers Company) discloses cationic
di-esters of the formula
R'COOCHa
CH-CH_-NR;R,R, X-
/
RSCOO
wherein R1, R. and R3 are each an alkyl or hydroxyalkyl group
containing from 1 to 4 carbon atoms, or a benzyl group, R,
and Rsare each alkyl chains containing from 11 to 23 carbon
atoms and X- is a water soluble anion.
One of the problems associated with fabric softening
compositions containing cationic di-esters as disclosed in US
4 137 180 is the physical instability of these compounds, the
problem is exacerbated at temperatures above or below
ambient.
EP 280 550 and EP 507 478 (Unilever) discloses the use of
selected nonionic stabilising agents to overcome the poor
stability. However we have found that many nonionic
stabilising agents create a further problem in that their
presence destroys the viscosity of these fabric softening
compositions.
EP 409 504 (Unilever ) discloses fabric softening
compositions comprising at least 1% w/w of an ester linked
quat and an extruder material which can be esters of
predominantly linear Ca-C28 fatty acids with polyhydric
alcohols.
AMENDED SHSEi'
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WO 95/27777 discloses rinse conditioners comprising a fabric
softening compound and a solubilising agent to be coated
onto a tufible dryer sheet.
We have now found that selected nonionic stabilising agents
do not destroy the viscosity of fabric softening compositions
containing a biodegradable quaternary ammonium material.
Description of the Invention
Accordingly the present invention relates to a fabric
softening composition comprising:
~-.
AMENDED SHEET
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a) a water insoluble, quaternary ammonium material
comprising one ester link and two C12_28 alkyl or alkenyl
groups;
} 5 b) a nonionic stabilising agent;
characterised in that the nonionic stabilising agent is a
sucrose ester or an alkyl polyglucoside.
Further disclosed is a process for making a liquid fabric
softening composition comprising the steps of selecting the
following ingredients:
a) a water insoluble, quaternary ammonium material having
at least one ester link and two C12_28 alkyl or alkenyl
groups;
b) a nonionic stabilising agent which is either a sucrose
ester or an alkyl polyglucoside;
c) other optional ingredients;
mixing the ingredients whilst heating to form a melt,
followed by dispersing the melt in hot water to give the
rinse conditioner.
Detailed Describtion of the Invention
The present invention is a way of controlling the viscosity
of a fabric conditioner composition containing a
biodegradable quaternary ammonium material and a nonionic
stabilising agent. Suitable nonionic stabilising agents
include the sucrose esters such as sucrose distearate and
sucrose monostearate, and the alkyl polyglucosides such as
stearyl monoglucosides and stearyl triglucoside.
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Without wishing to bound by theory, this invention is thought
to operate in that the interaction of the hydrogen bonding
elements of the molecules of the nonionic stabilising agent
are essential to maintain a vesicular structure. A vesicular
structure in the context of this invention can be defined as
a spherical structure having onion ring shaped bilayers. The
presence of such vesicular structures are an important
factor in the formation of a composition with a commercially
acceptable viscosity.
The preferred level of nonionic stabilising agent present is
0.1 to 2.5 % by weight.
Most preferred nonionic stabilising agents are the sucrose
esters. The sucrose esters have the additional benefit that
they impart additional softening benefits over the cationic
softening agent. Examples of suitable sucrose esters include
the Crodesta (Trademark (ex Croda)) series. Crodestas are
sucrose esters esterified with 70/30 mixture of
stearic/palmitic acid to form a mixes of mono-ester, di-ester
and triester. According to.the manufacturer the levels of
mono-ester are as follows:
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Trade Name wt % monoester
Crodesta F10 3
Crodesta F20 10
Crodesta F50 29
Crodesta F70 56
Crodesta F110 52
Crodesta F140 57
Crodesta F160 - 75
We have found that these combination of mono-esters and di-
esters and triesters of sucrose give particularly good
softening benefits. Especially preferred are combinations of
mono-ester, di-ester and triester that contain 56-75%
monoester, in particular Crodesta F160, Crodesta F140,
Crodesta 110 and Crodesta F70.
The fabric softening compound is suitably a substantially
water insoluble quaternary ammonium material comprising a
polar head group and two alkyl or alkenyl chains each having
an average chain length greater than or equal to C14, and at
least one ester group.
Preferably the fabric softening compound of the invention has
two long chain alkyl or alkenyl chains, each having an
average chain length greater than or equal to C16. Most
preferably at least 50% of each long chain alkyl or alkenyl
group has a chain of C.
It is preferred if the long chain alkyl or alkenyl groups of
the fabric softening compound are predominantly linear.
The fabric softening compounds used in the compositions of
the invention are molecules which provide excellent
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softening, and characterised by a chain melting -LP to LOG -
transition temperature greater than 25 C, preferably greater
than 35 C, most preferably greater than 45 C. This Lp to La
transition can be measured by DSC as defined in "Handbook of
ti
Lipod Bilayers, D Marsh, CRS Press, Boca Raton Florida, 1990
(Pages 137 and 337).
Substantially insoluble fabric softening compounds in the
context of this invention are defined as fabric softening
compounds having a solubility less than 1 x 10-3 wt% in
demineralised water at 20 C. Preferably the fabric softening
compounds have a solubility less than 1 x 10-4. Most
preferably the fabric softening compounds have a solubility
at 20 C in demineralised water from 1 x 10-8 to 1 x 10'6.
It is especially preferred if the fabric softening compound
is a water insoluble quaternary ammonium material which
comprises a compound having two C1._la alkyl or alkenyl groups
connected to the molecule via at least one ester link. It is
more preferred if the quaternary ammonium material has two
ester links present. An especially preferred ester-linked
quaternary ammonium material for use in the invention can be
represented by the formula:
R'
I
R' = N' (CH,) n-T-R2 X'
I
(CH; ) ,,-T-R'
wherein each R1 group is independently selected from C1_4
alkyl, hydroxyalkyl or C1_, alkenyl groups; and wherein each
R= group is independently selected from C$_a8 alkyl or alkenyl
groups; X- is any suitable anion. 35
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0 0
T is -O-C- or -C-O-; and
n is an integer from 0-5.
Di(tallowyloxyethyl) dimethyl ammonium chloride is especially
preferred.
A second preferred type of quaternary ammonium material can
be represented by the formula
OOCR'
( R1) 3N' - (CH2 ) n CH X-
CH2O O CRZ
wherein R1, X-, n and R 2 are as defined above.
Preferred materials of this class such as 1,2 bis[hardened
tallowoyloxy]-3- trimethylammonium propane chloride and their
method of preparation are, for example, described in
US 4 137 180 (Lever Brothers). Preferably these materials
comprise small amounts of the corresponding monoester as
described in US 4 137 180 for example 1-hardened
tallowoyloxy-2-hydroxy-3- trimethylammonium propane chloride.
It is preferred if the quaternary ammonium compound is
biodegradable. Biodegradable in the context of this
invention should be interpreted as meaning degrades to
materials that are not known to be harmful to the
environment.
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The ratio of quaternary ammonium material to nonionic
stabilising agent is in the range from 5:0.5 to 5:0.1.
The composition may also contain long chain fatty acid
material for example C8 - Caq alkyl or alkenyl monocarboxylic
acids or polymers thereof. Preferably saturated fatty acids
are used, in particular hardened tallow C16 - C18 fatty acids.
Preferably the fatty acid is non-saponified, more preferably
the fatty acid is free for example oleic acid. lauric acid or
tallow fatty acid.
The level of fatty acid material is preferably more than
0.1%, more preferably more than 0.2% by weight. Especially
preferred are dilutes in which the fatty acid material is
present from 0.25 wt% to 20 wt%. The weight ratio of
quaternary ammonium compound to fatty acid material is
preferably from 1:10 to 10:1.
It is desirable if the viscosities of these fabric
compositions lie in the range from 15 mPa.s to 120 mPa.s at
a shear rate of 110s-1.
The compositions of the invention preferably have a pH of
more than 2, more preferably between 2 and S.
The composition-can also contain one or more optional
ingredients, selected from the group consisting of non-
aqueous solvents, pH buffering agents, perfumes, perfume
carriers, fluorescers, colorants, hydrotopes, antifoaming
agents, antiredeposition agents, enzymes, optical
brighteners, opacifiers, antishrinking agents, drape
imparting agents, antistatic agents and ironing aids.
The composition may also contain nonionic fabric softening
agents such as lanolin and derivatives thereof.
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The invention will now be illustrated by the following non-
limiting examples.
EXAMPLES
in the examples all percentages are expressed by weight.
Comparative examples are represented by a letter while
examples of the invention are represented by a number.
In the Examples HEQ is 1,2 bis[hardened tallowoyloxy]-3-
trimethylammonium propane chloride ex Hoechst.
Preparation of Fa]2ric Conditionina Composition
Liquid fabric softening agents were made up as follows:
The cationic fabric softening agent and/or fatty acid and/or
nonionic stabilising agent where appropriate were premixed
and heated together to form a clear melt. The molten mixture
thus formed was added over a period of at least one minute to
water at 70 C to 80 C with constant stirring to form a
dispersion.
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S (i g Co_a ity.Mansr P~ t s
Viscosity was measured using the Haakem RV20 Rotov.i3cometer.
Viscosity is quoted ac a shear rate of 10s''. The Casson data
are obtained by using the Casson relationship:
T0.5_T0 D0.3
Where:
= Shear Stress (Pa)
TQ
= Yield Stress (Pa)
= infinite shear rate viscosity (raPa.s)
D
= Shear rate (s'' )
The Casson data were generated using the Haake RV20
Rotoviscometer with a range of shear rates from 0-1000s''.
F-xam,,.n1 _2 Conibaratiye Examolga A-D
Compositions were prepared in which an aqueous dispersion of
5t 6:1 HEQ:fatty acid, 0.5% of the following nonionics were
added:
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T bel
Example Nonionic
A No nonionic
B Genapol" T-150
C Tween" 80
D Tween 85
1 Crodesta F50
2 Crodesta F110
Genapol, Tween and Crodesta are trade marks.
The effect of nonionic type on viscosity of a dilute
quaternary ammonium compound is shown in Table 2.
Table 2
Example 1i,o (mPa . s) (1I.(mpa.g) ICcament.
A 66 14.2 Vesicular
B 26 4.6 No vesicles
C 15 5.4 No vesicles
D 16 8.4 No vesicles
1 87 22.0 Vesicles
2 48 12.3 Vesicles
It can be seen that in the absence of nonionic the
composition has a vesicular structure and accordingly has an
acceptable viscosity. However the presence of nonionics
stabilising agents which are not as specified by this
invention, such as Genapol T-150, Tween 80 and
'I*ween 85, do not allow vesicle formation and hence the
viscosity of the composition is unacceptably low. The
examples according to the invention allow vesicle formation
and so have an acceptably high viscosity.
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Co=arat i ve Examnl .s E-G
Compositions were prepared in which 0.5% of the following
nonionic were placed in a composition containing an aqueous
dispersion of 5% 6:1 dihardened tallow dimethyl ammonium
chloride:fatty acid.
Example E No nonionic
Example F Genapol T-150
Example G Crodesta F50
The results are shown in Table 3.
Table 3
Example T1110(mPa.s) Tl..(mPa.s) Comments
E 184 21.8 Vesicular
F 238 10.9 Vesicular
G --- ---- Vesicular
Table 3 demonstrates that nonionic stabilising agents do not
destroy the viscosity in formulations containing dihardened
tallow dimethyl ammonium chloride.
Examnles 3-10 Comoarative Exambles A-B
To a base formulation of 5% HEQ:Hardened tallow fatty acid
6:1 in water the following nonionic stabilising agents were
added:
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= Example 3 0.25 % Crodesta F160
Example 4 0.50 % Crodesta F160
Example 5 0.50 % Crodesta F10
Example 6 0.50 % Crodesta F20
Example 7 0.50 % Crodesta F50
Example 8 0.50% Crodesta F70
Example 9 0.50% Crodesta F110
Example 10 0.50 % Crodesta F160
The softening performance of the sugar esters are
demonstrated by Table 4.
Table 4
Examples SScore Total Votes
3 0.8828 31
4 1.0750 37
A 0.0000 6
B 0.5862 22
95% significance is obtained with a difference (A) between
products of 0.9041. 90% significance is obtained when
A=0.7565. it is thus demonstrated that the sucrose esters
exhibit a significant softening benefit.
Table 5 demonstrates the optimum level of mono-ester present
to maximise the softening effect.
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Table 5 '
F.2rsLm2jo Softenina Score yotes
0.0000 17
6 0.1689 25
7 0.2136 27
8 0.9444 54
9 1.3931 71
10 0.7005 46