Note: Descriptions are shown in the official language in which they were submitted.
Field of the Invention
This invention relates to hypochlorite bleach com-
positions and in particular to aqueous hydrochlorite
bleaches containing a bactericidal material.
Background of the Invention
Aqueous bleach compositions containing alkali metal
hypohalites, particularly sodium hypochlorite, have been
known for many years. Because of their powerful oxidis-
ing action they have also been acknowledged to be power-
ful germicides and have been used extensively where thisproperty is beneficial, e.g. in the cleaning of baths,
wash basins, flush toilets, drains and ceramic tile
floors. However, it has long been recognised that the
germicidal effectiveness of surface treatments using such
materials is limited by the relatively short period of
time during which the aqueous composition containing the
hypohalite is in contact with the surface concerned.
Recent developments in the formulation of hypochlorite
bleach products have shown a trend towards the use of
higher viscosities, viz. 100 centistokes or greater,
and this will increase the retention of such products
on non horizontal surfaces.
Nevertheless, the increase in retention time in-
troduced by such a thickened formulation will not be
particularly significant, being measured in seconds or
at most minutes 9 and a need exists for a bactericidal
and germicidal material that is capable of retention
on a target surface for much longer periods.
Quaternary ammonium compounds, in general, are known
to have bactericidal characteristics, and certain water
soluble ~uaternary ammonium surfactants such as cetyl py-
ridinium bromide are very effective antibacterial agents.
Polymeric dialkyl siloxane and silane structures are well
known as having a high affinity for siliceous surfaces and
thus a combination of a quaternary ammonium function and a
siloxane or silane grouping might be expected to provide a
long lasting antibacterial effect on siliceous surfaces
of the type mentioned above. Such is indeed the case and
the antimicrobial effectiveness of a representative alkoxy
silane (3(trimethoxy silyl)propyl dimethyl octadecyl ammo-
nium chloride) on a variety of surfaces, siliceous, metal-
lic, synthetic, plastic and natural textile in nature,
has been reported by A.J. Isquith et al in J. Applied
Microbiology, 24 (h), 1972, pp. 859-863.
However, the incorporation of quaternised alkoxy
silanes into aqueous cleaning or bleaching compositions
poses considerable difficulty. All alkoxy silanes of
this type will hydrolyse in contact with water, to pro-
duce the corresponding silanol derivative which them-
selves are prone to polymerisation via condensation of
the silanol groups. The pol~merised materials are less
surface substantive than the parent silanols.
In the case of the more water soluble alkoxy silanes,
containing a C12-C14 alkyl group in the quaternary
ammonium portion of the molecule; the materials display
physical stability in aqueous alkalis and commercial
aqueous hypochlorite and also display surface substantive
properties. However, in the presence of hypochlorite-
stable surfactants, surface substantivity is markedly
impaired due to solubilisation into surfactant micelles.
Furthermore, these shorter chain alkyl quaternised alkoxy
silanes do not display broad range antibacterial efficacy.
Quaternary alkoxy silanes containing an alkyl chain
longer than C14 are less water soluble and do not even
display lonq term stability in aqueous alkaline solutions
but precipitate therefrom, probably in polymerised, and
hence antibacterially ineffective, form.
However, it has surprisingly been found that those
quaternised alko~y silanes containing a C16-C20 alkyl
group can be incorporated into an aqueous hypochlorite
bleach composition to produce a physically stable product
capable of delivering a long lasting antibacterial effec-t
to siliceous surfaces treated therewith.
Aqueous hypochlorite bleach compositions forming
suitable vehicles for the delivery of the quaternised
alkoxy silanes should be free of anionic surfactants and
preferably should have a low ionic strength.
Accordingly the present invention provides an aqueous
bleaching composition comprising from 0.1~-5~ by weight
of a surfactant selected from amine oxides of formula
R4R5R6N ~O, wherein R4 is a C10-Cl8 alkyl group and R5
and R6 are Cl-C4 alkyl groups substituted betaines of
formula R7R8RgN -R COO wherein R7 is a C8-C18 alkyl
group, R8 and Rg are Cl-C4 alkyl groups and Rlo is a Cl-C4
alkylene group, and mixtures thereof, from 1.0% to 12.0%
by weight of an alkali metal hypochlorite and from 1.0% to
15% by weight of inorganic compounds other than hypochlor-
ite, said composition having a pH in the range frGm 10 to
12, wherein the composition also contains from 0.001-0.25~
by weight of an organosilicon quaternary ammonium compound
of formula
R2
tR3)y(R30)3_ySi(CH2)3N R
~2
Rl is C16 C20 alkYl/ R2 is Cl-C4 alkyl, R
is Cl-C4 alkyl, y is an integer from 0 to 2, and X is
a water soluble anion or the silanol derivative thereof
wherein R3 is H;
wherein the ionic strength of the composition is less than
5.0g moles/dm3 and wherein the composition is free of
anionic surfactant species.
Preferably the composition contains from 0.005% to
0.05% and most preferably from 0.01% to 0~03% of the
organosilicon quaternary ammonium compoundO Preferably
Rl is a C18 alkyl group.
In highly preferred compositions in accordance with
the invention, the viscosity of the composition is at
least 200 centipoises at 20C and comprises alkali metal
hypochlorite in an amount of from 8% to 10% by weight, a
C14-C15 alkyl dimethyl amine oxide as the only surfactant
in an amount of from 1.0 to 1.5% by weight together with
at least 400 ppm of a monocyclic or bicyclic monoterpene
alcohol or the ester thereof with a C2-C3 alkanoic acid,
and the composition has an ionic strength of less than
4.0 g moles/dm3.
The above mentioned reference to viscosity is to the
dynamic viscosity ~ which is measured by a Brookfield RVT
viscometer and for the purposes of this specification
measurements are made with Spindle No. 3 at 100 rpm and
a liquid temperature of 20C. Fluid viscosity can also
be expressed as the kinematic viscosity y in centistokes
as measured by an Ostwald viscometer and is characterised
by the expression y = ~/p where n is the dynamic viscosity
in centipoises and p is the density in g/cm3. Compositions
in-accordance with the present invention have a density in
the range from 1.10 to 1.25 g/cm3, typically approximately
1.15 g/cm , so that the numerical value o~ the kinematic
viscosity in centistokes is slightly less than that of the
dynamic viscosity in centipoises.
Organosilicon quaternary ammonium compounds having the
desired combination of broad spectrum antibacterial acti-
vity and physico chemical stability in compositions in
accordance with the invention have the general structure:
~R3~ylR30l3_ysi (C32)3--~ Rl ~
1 s C16 C20 alkyl, R2 is Cl-C4 alkyl R
is Cl-C4 alkyl, y is an integer from 0 to 2, and X
-t~
-- 5 --
is a water soluble anion. A preferred chain length for
Rl is C18 for antibacterial efficacy reasons, and for rea-
sons of cost and ease of preparation R2 and R3 are usually
methyl. In aqueous alkaline solution the (R30) groups will
hydrolyse to give the silanol derivative so that refer-
ences herein to the organic silicon quaternary am~onium
compound include the silanol derivative thereof. X is
normally halide, particularly chloride, but can also
include methosulphate, acetate or phosphate.
The level of incorporation of the organosilicon com-
pound is from 0.001% to 0.25% based on the total weight
of the composition but is more usually in ~he range of
from 0.005% to 0.05% and most preferably from 0.01% to
0.03% by weight.
In compositions in accordance with the invention, the
hypochlorite bleach, and the alkali metal chloride and
chlorate salts which accompany it in commercially available
material, provide the majority and preferably substantially
all of the ionic strength requirement. This will normally
result in an ionic strength of at least 3.0 9 moles/dm3.
Ionic strength values in excess of 5.0 g moles/dm3 are not
desirable because of their adverse influence on the stabi-
lity of both the hypochlorite and organosilicon quaternary
ammonium compound components. Preferably the ionic strength
is less than 4.0 g moles/dm3 and values in the region of
3.4-3.8 g moles/dm are considered to be optimum where a
stable product of viscosity <200 centipoises is desired.
The alkali metal hypochlorite may be a lithium, potas-
sium or sodium hypochlorite and the level of hypochlorite
in the composition is normally arranged to lie in the
range 1-12%, preferably 5-10~ by weight. Customarily
hypochlorite bleach compositions contain approximately
6% or 9% hypochlorite by weight. However, the activity
of chlorine bleaching compositions is conventionally ex-
pressed in terms of the weight percentage of available
chlorine in the composition, and the actual weight per-
centage of bleaching species is arranged to provide the
desired level o~ 'available chloride'. The preferred
hypochlorite species is sodium hypochlorite which con-
tains 95.3% available chlorine.
.~
Yt
-- 6
Alkali metal hypochlorites are commercially availableas aqueous solutions containing 10-15~ by weight 'avail-
able chlorine' and the bulk suppliers normally produce
material having available chlorine contents towards the
upper end of this range viz. 12-14% by weight. These
commerci~lly available hypochlorite solutions contain
other salts as byproducts or contaminants, more speci-
fically free alkalinity in the form of alkali metal
hydroxide and alkali metal carbonate, and alkali metal
chloride. Low levels of other species such as sodium
chlorate are also believed to be formed during hypo-
chlorite manufacture but their chemical stability is
sufficiently low that they have largely decomposed by
the time the hypochlorite is employed in product for-
mulations. The levels of the byproduct materials depend
on the processing conditions employed in the manufacture
of the hypochlorite but in general they fall within the
ranges
0.2 - 1.0% alkali metal hydroxide
0.01 - 0.1% alkali metal carbonate
10.0 - 18.0% alkali metal chloride
expressed as a weight percentage of the hypochlorite
solution as supplied.
Amine oxides useful in the present invention have the
formula R4R5R6N -sO wherein R4 is a C10-C18 alkyl group
and R5 and R6 are Cl-C4 alkyl groups. The amine oxide is
present in an amount oE from 0.5% to 5%, more preferably
from 0.5~ to 2.5% and, in preferred embodiments of the
invention in which the R4 average chain length 14 carbon
3a atoms, from 1% to 1.5~ by weight of the composition. The
R4 group may be linear or branched and may be derived from
natural or synthetic hydrocarbon sources. For the pur-
poses of the present invention linear groups are defined
as including moieties incorporating up to 25% methyl
branching, predominantly in the 2-position relative to
the nitrogen atom of the amine oxide.
Methyl branching on the alkyl chain also predominates
in those amine oxides useful in the present invention in
which the R4 group is branched, rather than linear in
nature.
7~
-- 7 --
Commercially available sources of these amine oxides
are normally a mixture of
R5
J
R - CH- CH2 _ N ~ O where R7 is methyl and
R
R5
R ---CH2- CH2 -N - -~o
R6
which mixture arises as a result of the processing route
used to form the precursor alcohol or aldehyde. This
route involves carbonylating or hydroformylating an ole-
fin, preferably a line~r -olefin and leads to a mixture
of the desired branched chain aldehyde or alcohol of the
same carbon number. For olefin starting materials having
a range of carbon chain length, the resultant alcohol or
aldehyde mixture contains compounds of different carbon
number and isomers containing straight chain and 2-alkyl
branched chain alkyl groups. A typical commercially
available mixture comprises 65 to 75% by weight C13 and
35 to 25% by weight C15 amine oxides with approximately
50% by weight straight chain and 50% by weight 2-alkyl
branched chain where the 2-alkyl group is predominantly
methyl. These are available from IC~ under the trade mark
Synprolam 35 DMO as a 30% aqueous solution. The branched
chain amine oxides and mixtures thereof with linear chain
amine oxides are used at levels towards the upper end of
the range viz. ~2% by weight of the composition and typi-
cally from 2.0% to 2.5% by weight.
Although the above-described mixture of straight chain
and branched chain alkyl dimethyl amine oxides has been
found suitable for the purposes of the invention, their
use does not constitute the most preferred execution of
the invention. This is because a bleaching composition
containing 8-10% hypochlorite and an amine oxide in which
the long chain alkyl group has a carbon number o~ about
63.3 requires an ionic strength of at least 4.7 g moles/dm3
-- 8
to achieve the preferred product viscosity of at least 200
cp. This level of ionic strength is believed to make the
storage stability of the hypochlorite bleach less than
that which is considered desirable for the expected shelf
life of the product. The preferred amine oxide structure
for 'thickened' products having a viscosity of >200 cp is
one in which R4 has an average chain length in the range
C14-C15. Compositions containing these preferred amine
oxides require a lower amine oxide level viz. <2.0~, more
typically 1.0-1.5% and also a lower ionic strength viz.
3.0 g moles/dm3 minimum in order to achieve target vis-
cosity. Another hypochlorite-stable surfactant suitable
for the purposes of the present invention is a substituted
betaine of formula
+
R7R8RgN -Rl COO
wherein R7 is a C8-C18 alkyl group, preferably a C10-Cl4
alkyl group, R8 and Rg are Cl-C4 alkyl groups, more pre-
ferably methyl groups, and Rlo is a Cl-C4 alkylene group
more preferably a C2-C3 alkylene group. Specific examples
include octyl, decyl, dodecyl, tetradecyl and hexdecyl
betaines in which Rlo is an ethylene or propylene group
and R8 and Rg are methyl groups. Both of these reductions
in ingredient level lead to improved storage stability and
also lower the co~t of the product.
A highly preferred optional component for hypochlo-
rite bleach compositions suitable for incorporating the
quaternised alkoxy silanes, particularly those utilising
an amine oxide wherein Rl has an average chain length of
about 14 carbon atoms, is at least one monocyclic or bi-
cyclic monoterpene alcohol or the ester thereof with aC2-C3 alkanoic acid, in an amount of at least 400 ppm
based on the weight o~ the composition.
Monocyclic and bicyclic monoterpene alcohols and their
esters with C2-C3 alkanoic acids are known and used as
ingredients in fragrances, including those employed in
detergent compositions. As such their level of incorpora-
tion varies from 10 - 500 ppm of the composition depending
on the perfume formulation and the nature of the detergent
composition.
~L7~
It has now surprisingly been found that in aqueous
hypochlorite bleach solutions containing from 1.0% to
2.5% of a C14-C16 amine oxide as the only surfactant,
the incorporation of at least ~00 ppm of at least one
monocyclic or bicyclic monoterpene alcohol or the ester
thereof with C2-C3 alkanoic acid provides an enhance-
ment of the viscosity of the bleach solution and faci-
litates the generation of viscosities of 200 centipoises
and greater at 20C. Preferably the monoterpene alcohol
or ester is present in an amount of at least 600 ppm.
Examples of materials demonstrating this effect are
isoborneol, isobornyl acetate, dihydroterpineol and
dihydroterpinyl acetate.
The mode of operation of these materials in this
system is not fully understood but it is hypothesised
that in the absence of anionic surfactants hydrogen
bonding occurs between adjacent alcohol functions of
the relatively water insoluble terpene alcohols held
in the amine oxide micelles. This leads to the forma-
tion of an extended micellar structure in the solution
which provides an increased viscosity.
Thickened aqueous hypochlorite bleach compositions
including the above mentioned terpene alcohol derivatives
are particularly preferred for the incorporation of the
quaternised alkoxy silane antibacterial component as such
compositions utilise the minimum amounts of amine oxide
surfactant and ionic salts necessary to generate the de-
sired product viscosity and hence enhance the stability
o~ the quaternised alkoxy silanes.
As stated hereinbefore, the salts accompanying
the hypochlorite bleach provide most if not all of the
ionisable species necessary for the ionic strength re-
quirement. ~owever, other non surface active organic
or inorganic compounds can be added where necessary to
provide an ionic strength in the desired range.
The ionisable compound(s) can be inorganic in nature
e.g. hydroxide, sulphate, halide, (particularly chloride),
carbonate, nitrate, or orthophosphate, pyrophosphate, or
polyphosphate, or organic such as formate, acetate or
succinate.
~7~
-- 10 --
In the preferred embodiments of the invention inor-
ganic compounds such as silicates and organic compounds
incorporating oxidisable groups are avoided because of
their tendency to have adverse effects on physical and/or
chemical stability of the compositions on storage. Cer-
tain organic sequestrants such as the amino poly (alkyl-
ene phosphonates) salts can, however, be incorporated
in an oxidised form in which they are not susceptible to
attack by the hypochlorite bleach. Such sequestrants are
normally present in amounts of from 0.1% to 0.5% by weight
of the composition.
The ionic strength of the composition is calculated
by means of the expression
Total Ionic Strength I = ~ C zi 2
where Ci is the molar concentration of the ionic
species in g moles/dm
Zi is the valency of the species.
The function CiZi2 is calculated for each of the ionic
species in solution, these functions are summed and
divided by two to give the composition ionic strength.
The ionisable alkali metal compound normally comprises
a caustic alkali such as sodium or potassium hydroxide
either alone or in admixture with alkali metal salts. For
product safety reasons the amount of caustic alkali is
normally limited to a value in the range of from 0.5% to
2~, more usually from 0.75% to 1.5~ by weight of the
composition.
A desirable optional component of compositions in ac-
cordance with the invention is a perfume which is present
at a level of from 0~01% to 0.5% preferably from 0.05%
to 0.25% by weight of the composition. In the preferred
thickened bleach compositions incorporating a monocyclic
or bicyclic monoterpene alcohol component this can con-
veniently be incorporated in the perfume mixture.
7~
-- 11 --
The compositions are made by conventional mixing
techniques. ~ecause of the relatively low aqueous
solubility of the organo silicon compound which is
normally supplied as a solution in methanol, a premix
of the amine oxide, perfume, added caustic alkali and
water is normally prepared and the organo silicon com-
pound is then added with vigorous agitation.
This mixture is then added to the hypochlorite solu-
tion to make the final product. Other orders of addi-
tion can be used but unless the amine oxide is presentin the solution to which the organo silicon compound
solution is added, problems of incomplete solution or
precipitation can arise.
The invention is illustrated in the following exam-
ples in which percentages are expressed by weight of the
composition unless otherwise stated.
In the Examples, reference to ingredients have been
abbreviated as follows:
ClsDMAO C15 alkyl dimethyl amine oxide
in which the alkyl group is 95%
Cls and approximately 50% of
the alkyl groups contain methyl
branching on the 2-carbon atom.
C14DMAO C14 alkyl dimethyl amine oxide
in which the alkyl group is a
predominantly linear C14 ( 94%)
moiety, Available from Albright
& Wilson Ltd. as Empigen OH.
NaCl Sodium chloride
NaOH Sodium hydroxide
NaOCl Sodium hypochlorite
NaPyro Tetra sodium pyrophosphate
K Pyro Tetra potassium pyrophosphate
EXAMPLE 1
420 9 of a 30% solution of C14 alkyl dimethyl amine
oxide was added to 3555.6 9 of demineralised water and 12.5 9
of a perfume material containing 6.4 g of isobornyl acetate
was dispersed therein. To this solution was slowly added,
with vigorous agitation, 11.9 9 of a 42% solution in metha-
nol of 3(trimethoxy silyl) propyl dimethyl octadecyl ammonium
~ ~,
7~
12
chloride (available from Dow Corning Ltd as DC 5700) to forlt
a premix solution. 125 9 of solid sodium hydroxide was
dissolved in 5875 g of sodium hypochlorite solution (15.3%
AvCl2 solution supplied by ICI Ltd) and 4000 g of the
premix was then blended with high shear agitation into this
solution.
This composition had the ollowing analysis, in percent
-;~,. by weight and had a de~sity of 1.15 g/cm2.
NaOCl 9.43 (= ~ available chlorine) 1.46 g moles~dm3
NaC1 9~40 1.84 "
NaOH 1.25 0.36
Amine
Oxide 1.26
DC5700 0.05
Perfume 0.125
Water ~
Misc 78.4~5
.
lC0.000
This product was a single phase solution having a dynamic
viscosity of 270 centipoises as measured at 20C with a
Brookfield viscometer using the No. 3 spindle at 100 rpm on
product that was 24 hours old.
The ionic strength of this compos-ition ~Jas calculated to
be 3.66.
~XAMPLF. 2
The follo~ing compositions are prepared according to the
techn.i~ue of E~ample l:
(a) (b) ~c) (d)
Cl~DM~O 1.2 1.5 1.75
Cl5Di';~O 1.2
DC5700 0.02 0.02 0.02 0.02
~aOil 1.0 1.0 1.0 1.0
NaOCl 9.0 9.0 9~0 9.0
NaCl S.0 9.0 9,0 9.0
Isoborne.~l 0,05 0.06 0.04
Dihyd;:oterpinyl 0.06
aceta.e
t~r ~ i5C. to 10n
Vi5Gos:ity (cp) ~,50 190 245 324
The density of each of these compositions is 1.15 g/ml
and the ionic strength for each composition is calculated to
be 3.5 g moles/dm3. The product viscosity was measured at
20C using the technique of Examplç 1.
