CA1217004A

CA1217004A - Cleaning compositions

Info

Publication number: CA1217004A
Application number: CA000454934A
Authority: CA
Inventors: Frederick E. Hardy; Barry Stoddart
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1983-05-25
Filing date: 1984-05-23
Publication date: 1987-01-27
Also published as: IE57534B1; ES532754A0; ATE40151T1; JPS6063300A; ES8603944A1; JPH0455480B2; IE841296L; GB8314500D0; DE3476220D1; EP0129980A3; GR81613B; EP0129980A2; EP0129980B1

Abstract

Abstract Aqueous hypochlorite bleach compositions are provided comprising from 0.1% to 5.0% of a C10-C8 alkyl C1-C4 alkyl diamine oxide or a C8-C18 alkyl substituted betaine together with from 0.001% to 0.25% of an organosilican quaternary ammonium compound containing a C16-C20 alkyl group, the compositions having a viscosity of ? 200 centi-poises at 20°C and an ionic strength of less than 5.0 g moles/dm3.

Description

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 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~

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 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~

Commercially available sources of these amine oxides are normally a mixture of J

R - CH- CH2 _ N ~ O where R7 is methyl and R

R ---CH2- CH2 -N - -~o 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 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~

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~

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 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~

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.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A stable, aqueous bleaching composition consisting essentially of from about 0.1% to about 5% by weight of a surfactant selected from the group consisting of amine oxides of formula R4R5R6N?O, wherein R4 is a C10-C18 alkyl group and R5 and R6 are C1-C4 alkyl groups, sub-stituted betaines of formula R7R8R9N+-R10COO- wherein R7 is a C8-C18 alkyl group and R8, and R9 are C1-C4 alkyl groups, and R10 is a C1-C4 alkylene group; and mixtures thereof, from about 1.0% to about 12.0% by weight of an alkali metal hypochlorite and from about 1.0% to about 15%
by weight of inorganic compounds other than hypochlorite, said composition having a pH in the range from about 10 to about 12, wherein the composition also contains from about 0.001 to about 0.25% by weight of an organosilicon quater-nary ammonium compound of the formula X-wherein R1 is C16-C20 alkyl, R2 is C1-C4 alkyl, R3 is C1-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 at least about 3 g moles/dm3 to less than about 5.0 g moles/dm3, and wherein the composition is substantially free of anionic surfactant species.

2. A bleaching composition according to claim 1 wherein R1 is C18 and X- is a halide anion.

3. A bleaching composition according to either one of claims 1 and 2 wherein the ionic strength of the compo-sition is less than 4.0 g moles/dm3.

4. A bleaching composition according to claim 1 wherein an alkyl dimethyl amine oxide in which the alkyl group has an average carbon chain length of from 14 to 15 carbon atoms is the only surfactant species present.

5. A stable, aqueous bleaching composition consisting essentially of from about 1.0% to about 2% by weight of an amine oxide of formula R4R5R6N?O, wherein R4 is an alkyl group having an average carbon chain length of 14 to 15 carbon atoms and R5 and R6 are methyl groups, from about 5.0% to about 10.0% by weight of an alkali metal hy-pochlorite and from about 1.0% to about 15% by weight of inorganic compounds other than hypochlorite, said composi-tion having a pH in the range from about 10 to about 12, wherein the composition also contains from about 0.005 to about 0.05% by weight of an organosilicon quaternary ammo-nium compound of formula X-wherein R1 is C18 alkyl, R2 is methyl, R3 is methyl, 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 at least 3 g moles/dm3 to less than about 4.0 g moles/dm3, and wherein the composition is free of anionic surfactant species.

6. A thickened bleach composition according to claim 5 wherein the composition contains a monocyclic or bicyclic monoterpene alcohol or an ester thereof with a C2-C3 al-kanoic acid in an amount of at least 400 ppm, whereby the composition has a viscosity of ?200 centipoise at 20°C.

7. A thickened bleach composition according to claim 6 wherein the amine oxide level is from about 1.0% to about 1.5% and the monocyclic or bicyclic monoterpene alcohol or an ester thereof with a C2-C3 alkanoic acid is present in an amount of at least about 600 ppm.

8. A thickened bleach composition according to claim 7 wherein the monocyclic or bicyclic monoterpene alcohol or an ester thereof with a C2-C3 alkanoic acid is selected from the group consisting of isoborneol, isobornyl ace-tate, dihydroterpineol, dihydroterpinyl acetate, and mixtures thereof.