CA1100382A - Liquid detergent compositions - Google Patents

Abstract

C 792 (R) Abstract of the Disclosure Stable, aqueous, heterogeneous built liquid deter-gent compositions are obtained using a detergent active, a mixture of sodium tripolyphosphate and sodium or potassium orthophosphate, and a copolymer of maleic anhydride with ethylene, styrene or vinylmethylether.

Description

~10(~3~3Z
C 792 t~) The invention relates to liquid detergent compositions which are suitable for fabric washing, and in particular to such compositions containing phosphate detergency builders.
Aqueous built liquid detergent compositions are well known in the art. Although they offer several advantages over other forms of detergent compositions like powders, such as improved solubility and easier dosing, their formu-lation is very difficult, since they should be physically stable under a wide rangé of storage conditions, for example from about -4C to +37C. Also they should have satisfactory pouring properties despite containing relatively high concentrations of detergent ingredients, especially builder salts so that ideally they have per-formances equivalent to the usual powdered detergent com-positions.
The prior art mainly teaches the use of more water soluble ingredients, such as tetrapotassium pyrophosphate, usually with expensive stabilising agents, but even then the amount which can be used is lower than would be desired in comparison with powdered detergent compositions.
Although such prior liquid formulations may provide acceptable compositions as far as their physical charac-teristics are concerned, their detergency and other l~ash-ing properties tend to be unsatisfactory. For exampl~, with the alkali metal.pyrophosphates there are often depo.,its formed on the clothes, especially when the products ~Ire used at exceptionally low product concentrations or -t 1~003~2 C 792 (R) high temperatures. When attempts have been made to improve the detergency, then the stability and pourability have become unsatisfactory. In particular, it has not been possible to incorporate into the liquid detergent compo-sitions sufficiently high levels of the conventional deter-gency builders such as sodium tripolyphosphate without causing severe problems of separation or solidification of the liquid compositions.
According to the present invention we have found that satisfactory, relatively high,'leve]s of certain mixtures of sodium tripolyphosphate and sodium or potassium orthophosphate may be incorporated into aqueous hetero-geneous stable liquid compositions, that is compositions with a suspended solid phase, which have good physical properties, with the aid of particular stabilising agents as described hereinafter. Instead of the sodium tripoly-phosphate the potassium salt may be used, but this is more expensive and for convenience the use of the sodium salt is described and illustrated in the specification.
Insofar as these two detergency builder materials function normally in different ways i.e. by sodium tripoly-phosphate acting as a sequestrant detergency builder and the alkali metal orthophosphate functioning as a precipitant builder, it is somewhat surprising that a mixture of ~he materials func-tions so effectively. In particular, when sodium orthophosphate 38~
C 792 (R) is used alone as a detergency builder it tends to cause inorganic deposition on the washed fabrics, which is accompanied by soil redeposition, but in the presence of the sodium tripolyphosphate the soil redeposition is sig-nificantly decreased whilst the detergency is apparently boosted. Moreover, in comparison with the use of sodium tri-polyphosphate alone as detergency builder, the same amount of the mixed sodium tripolyphosphate and alkali metal ortho-phosphate detergency builders shows improved detergency and soil redeposition properties, especi~ally in hard water.
There have in the past been many suggestions for using mixed phosphate detergency builders, for example mixtures of sodium pyrophosphate and sodium tripolyphosphate ? in liquid compositions, particularly those adapted for hard surface cleaning. Moreover, it is well known that the con-densed phosphates such as sodium tripolyphosphate tend tb degrade in aqueous alkaline conditions at high temperatures, which are often met during detergent processing conditions, so as to form other phosphates; for example sodium tripoly-phosphate tends to break down to give a mixture of sodium pyrophosphate and sodium orthophosphate.
However, to the Applicants' knowledge it has not been proposed hitherto to use the specific mixtures of sodium tripolyphosphate and alkali metal orthophosphate in the proportions as set out below in fabric washing liquid detergent compositions containing a suspended solid phase according to the present invention. The formation of the heterogeneous detergent compositons with r,luch higher 11~038Z
C 792 (R) detergency builder levels than has hitherto been possible is particularly advantageous. They can be made with good physical properties without very expensive multiple stabil-ising agent systems or complicated processing conditions.
The ratio of the sodium tripolyphosphate to the alkali metal orthophosphate in the detergent composition is from about 10:1 to about 1:10, particularly about 5:i to about 1:2 parts by weight, preferably from about 4:1 to about 2:3, and especially from about 3:1 to about 1:1 parts by weight.
These ratios of sodium tripolyphosphate to the alkali metal orthophosphate are chosen to give optimum detergency building and other washing properties in relation to the maximum amount of these ingredients which can be tolerated in the liquid compositions without loss of stability.
It will be appreciated that the actual amounts of sodium tripolyphosphate and alkali metal orthophosphate are chosen according to the overall phosphate detergency builder level which is desired or permitted in the liquid detergent compositions. However, it is normal to use a total amount of sodium tripolyphosphate plus alkali metal orthophosphate within the range of from about 5% to about 35% by weight of the composition, preferably from about 10% to about 30%, especially about 15% to about 25% by weight. It is also preferred that the individual amount of each of the sodium tripolyphosphate and the alkali metal orthophosphate should be at least about 2%, preferably at least about 4%
by weight of the composition.
~hen higher levels of sodium tripolyphosphate a-~e used, C 792 (R) i.e. above about 12% by weight of the composltion, it is particularly advantageous to use a type of sodium tripoly-phosphate which hydrates rapidly, as this aids its solubility, particularly for use in compositions containing higher levels of sodium tripolyphosphate. Suitable materials are commer-cially available with a high, i.e. greater than 50~, phase I
content, and they may also be partially or fully prehydrated.
Apart from the mixed phosphate detergency builders, the liquid detergent compositions of the invention contain a detergent active compound which may ,be an anionic, nonionic, amphoteric or zwitterionic detergent active compound or mixture thereof. Many suitable detergent active compounds are commercially available and are fully described in the literature, for example in "Surface Active Agents and Detergents", Volumes I and II, by Schwartz, Ferry and Berch.
The preferred detergent compounds which can be used are synthetic anionic compounds~ These are usually water soluble alkali metal salts of organic sulphates and s~lphonales having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium primary or second-ary alkyl sulphates, especially those obtained by sulphatingthe higher (C8-C18) alcohols produced by reducing the glycerides of tallow orcoconut oil;sodium and potassium alkyl (Cg-C20) benzene sulphonates, particularly sodium linear secondary alky L' (C~o-C15) benzene sulphonates; sodium alkyl glyceryl ether sulphates, es-pecially those ethers of the higher alcohols derived frcm tall(~Jor coconut 110~3~32 C 792 (R) oil and synthetic alcQhols derived from petroleum;sodium coconut oil fatty acid monoglyceride sulphates and sulphonates; sodium and potassium salts of sulphuric acid esters ofhigher (Cg-Cl8) fatty alcohol-alkylene oxide, particularly ethylene oxide, reac-tion products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutral-ised with sodium hydroxide; sodium and potassium salts of fatty acids amides of methyl taurine; primary or secondary alkane mono-sulphonates such as those derived by reacting alpha-olefins (C8-C20) with sodium bisulphite and those derived by reacting paraffins with S02 and C12 and then hydrolysing with a base to produce a random sulphonate; and olèfin sulphonates, which term is used to describe the material made by reacting olefins, par-ticularly alpha-olefins, with S03 and then neutralising and hydrolysing the reaction product.
Although in general the sodium salts of the anionic detergent compounds are preferred for cheapness, the potas-sium salts can sometimes be used to advantage, particularly in compositions with high levels of other sodium salts such as sodium tripolyphosphate and sodium orthophosphate.
Of the anionic detergent compounds, alkali metal alkyl C10-Cl5) benzene sulphates are particularly preferred, both for ready avail-ability a~d cheapness and also for their advantageous solubilityproperties.
If desired, nonionic detergent active compounds may be used as the sole detergent compounds, or preferably in admix-ture with anionic detergent compounds, especially the alkyl benzene sulphonates. Examples include the reaction products of alkylene oxides, usually ethylene oxide, with alkyl (C6-C22) phenols, generally 5 to 25 E0; i.e. 5 to 25 units of ethylene oxide per molecule; the condensation products 110C~3~32 C 792 (R) of aliphatic (C8-C18) primary or secondary alcohols with ethylene oxide, generally 2 to 30 EO, e.g. 6-20 EO, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine.
Another example of suitable nonionics are nonionics obtained by first ethoxylating and subsequently propoxylating an or-ganic hydroxyl-group containing radical, e.g. an aliphatic primary or secondary C8-C18 alcohol. Other so-called non-ionic detergent active compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and di-alkyl sulphoxides. I
Mixtures of detergent active compounds, for example mixed anionic or mixed anionic and nonionic compounds may be used in the detergent compositions, particularly to im-part thereto controlled low sudsing properties. This is particularly beneficial for compositions intended for use in suds-intolerant automatic washing machines. Mixtures of amine oxides and ethoxylated anionic compounds can also be beneficial.
Amounts of amphoteric or zwitterionic detergent active compounds can also be used in the liquid detergent compositions of the invention but this is not normally desired due to their relatively high cost. If any am-photeric or zwitterionic detergent active compounds are used it is generally in small amounts in compositions based on the much more commonly used anionic and/or non-ionic detergent active compounds. Soaps, i.e. alkali metal salts such as sodium or potassium salts of C10-C22 fatty acids such as coconut fatty acids and oleic acid, including 110(~38Z
- C 732 (R) polyme~ic fatty acids such as dimerized oleic acid, may also be used in the compositions of the invention, particularly in ternary mixtures with synthetic anionic and nonionic detergent active compounds, which have low sudsing properties.`
The amount of the detergent active compound or compounds used is generally in the range of from about 2.0% to about 20%, preferably about 5% to about 15%, by weight of the compositions, depending on the desired properties. Lower levels of nonionic detergent compounds should be used within this range as they tend to form a separate liquid phase if used at higher levels, that is over about 5% by weight. The ratio of the total detergent active compounds to the total of the amount of sodium tripolyphosphate and alkali metal orthophosphate should generally be in the range of from about 2:1 to about ~:5, preferably about 1:1 to about 1:3 parts by weight.
The alkali metal orthophosphate used may be sodium or potassium orthophosphate. The former is cheaper and more readily available but the latter may be advantageous:!y used, particularly at high total phosphate levels in the products. The potassium orthophosphate can be added as such, or orthophosphoric acid may be neutralised by a potassium salt such as potassium hydroxide during production of the compositions. It should be noted that the term alkali metal orthophosphate includes the mono-, di- and tri-ortho-phosphates.
In the liquid detergent compositions of the invlntion it is essential to have present a stabilising agent, 3~32 C 792 (R) particularly in compositions containing higher phosphate levels, to maintain stable suspensions of the solid phase an~/or to avoid separation of different liquid phases, particularly when nonionic detergent compounds are present. Suitable stabilising agents for these compositions are polymeric stabil-ising agents which are copolymers of maleic anhydride with either ethylene, styrene or preferably vinyl methyl ether.
Such materials are commercially available, for example under the trade name "Gantrez", for 1:1 copolymers of maleic an-~ hydride with vinyl methyl ether, whi'ch havè a specific vis-cosity of about 0.1 to 4.5, preferably 0.1 to 0.6 (measured in solution (1 g in 100 ml) of methyl ether ketone at 25 C).
Other copolymers of maleic anhydride with ethylene are avail-able under the trade name "EMA". The copolymers are hydro-lysed and neutralised in the compositions and they may also be partially esterified with any nonionic compound used. It should be noted that the presence of hydrotropes may be undesirable in the compositions, particularly at higher levels where they may detract from the stability of the products.
The amount of such copolymeric stabilising agents is preferably about 0.1% to about 2%, especially about 0.3%
to about 1.5~o~ by weight of the composition.
It is desirable to include one or more anti-depo-sition agents in the liquid detergent compositions of the invention, to decrease any tendency to form inorganic deposits on washed fabrics, especially under conditions of use at low product concentration. Examples of prefer~ed 110~3~3Z
C ~S2 (R) anti-de~position agents are homo- and copolyacrylates, e.g.
sodium polyacrylate, the sodium salt of copolymethacrylamide/
acrylic acid and sodium poly-alpha-hydroxyacrylate, and the sodium salts of polymaleic acid and polyitaconic acid. Such copolymers preferably have relatively low molecular weights, e.g. in the range of about 2,000 to 50,000. Other anti-deposition agents include phosphate esters of ethoxylated aliphatic alcohols, polyethylene glycol phosphate esters, and certain phosphonates such as sodium ethane-1-hydroxy-1,1-diphosphonate, ethylenediamine tetramethylene phosphonic acid and sodium 2-phosphonobutane tricarboxylate. The most preferred anti-deposition agent is sodium polyacrylate having a MW of about 2,000 to about 30,000, e.g. about 15 to 25,000.
The amount of such anti-deposition agents is generally about 0.1% to about 5.0%, preferably about 0.2% to about 2% by weight of the compositions.
It is also possible to include in the detergent com-positions of the invention minor amounts, for example up to about 10% by weight, of other detergency builders, which may be either so-called precipitant builders or sequestrant builders. This may be of particular benefit where it is desired to increase detergency whilst using particularly low levels of the essential sodium tripolyphosphate and alkali metal orthophosphate builders, so as to achie-~e particularly low phosphorus contents in the detergen~; com-positions for environmental reasons. Examples of suc~
other detergency builders are amine carboxylates, su h as sodium nitrilotriacetate. However, it is desirable t have -- ~.1 --11003~ c 792 (R) no other phosphate detergency builders present othe~ than the sodium tripolyphosphate and alkali metal orthophosphate, and in particular it is desirable to exclude pyrophosphates from the compositions as they tend to increase inorganic deposition and soil redeposition. Some pyrophosphate may be present for example as an impurity in the sodium tripoly-phosphate, or it may be produced by hydrolysis of the sodium tripolyphosphate during detergent processing, particularly under alkaline conditions at elevated temperatures, so low levels of sodium pyrophosphate may be unavoidable, but it is preferred to have no more than about 5%, especially less than about 2% by weight of pyrophosphate present in the compositions.
The liquid detergent compositions of the invention can contain any of the conventional additives in the amounts in which such additives are normally employed in liquid fabric washing detergent compositions Examples of these additives include lather boosters such as alkanolamides, particularly the monoethanolamides derived from palm kernel fatty acids and coconut fatty acids, lather depressants such as alkyl phosphates, silicones and long chain soaps, anti-redeposi-tion agents such as sodium carboxymethylcellulose, alkaline salts such as sodium silicate, alkali metal carbonate or alkali metal hydroxides, fabric softening agents , and, usually present in very minor amounts, fluorescent agents, perfumes, enzymes such as proteases and amylases, ger-micides and colourants.
The ~alance of the compositions is water, which is `` 110~38Z
C 792 (R) usually present to the extent of about 40% to about 75% by weight, preferably about 45% to about 65% by weight.
To ensure effective detergency the liquid detergent compositions should be alkaline, and it is preferred that they should provide a pH within the range of about 9 to 12, preferably about pH 9.5 to about 11 when used in aqueous solution of the composition at the recommended concentràtion.
To meet this requirement, the undiluted liquid composition should also be of high pH, for example about pH 11 to about 12.5. It should be noted that an excessively high pH, e.g.
over about pH 13 is less desirable for domestic safety. The ingredients in any such highly alkaline detergent composi-tion should of course be chosen for alkaline stability, es-pecially for pH-sensitive materials such as enzymes, and a particularly suitable proteolytic enzyme in this respect is available under the trade name "Esperase".
It is desirable to include in the compos1tion an alka-line buffer, for example alkali metal carbonate, to main-tain the pH of at least 9 during use, particularly under conditions of use, for example in hard water or at low product concentrations, when the alkali metal orthophos-phate is precipitated in the form of its calcium salt and cannot itself then act as the alkaline buffer. Aiternatively, alkali metal silicates, for example sodium ortho-~:meta- or preferably neutral or alkaline silicates may be used. The presence of such alkali metal silicates at low levels of, for example about 1% to about 5% by weight, is also ad-vantageous in decreasing the corrosion of metal part, in 110~382 C 792 (R) washing machines. An alkali metal hydroxide may alternatively or additionally be used to provide an i~itially high pH.
The liquid detergent compositions can be made relatively easily. It is preferable, particularly for products with lower sodium tripolyphosphate levels, to split the water required into two parts and one part is heated and then mixed with the inorganic builder salts and the other is mixed with the other organic ingredients. The two parts are then blended together to give a suspended liquid system. Alternatively, compositions of higher sodium tripol'yphosphate content in particular may be made by firstly dissolving a preformed copolymeric stabilising agent in water and partly ester-ifying the copolymer with some nonionic detergent active compound, adding the anionic detergent active compounds, any soap and any further nonionic compound to the resultant mixture, and then adding the phosphate salts and any sodium silicate. The heat of reaction between acidic and alkaline ingredients may be used to raise the temperature and facili-tate mixing of the ingredients.
The resultant compositions have viscosities in the range from about 50 to 2,000 centipoise, especially about 100 to about 1500 centipoise, as measured at room temperature in a Brookfield viscometer (Spindle No. 3, 30 rpm).
The invention is illustrated by the following Examples in which parts and percentages are by weight except where otherwise indicated.
Examples 1 ar.d 2 Two stable heterogeneous liquid compositions we~e made C 792 (R) to the-following formulations:
Ingredient Percentages Ex 1 Ex 2 Sodium alkyl (C11-C15) benzene sulphonate 6 6 Tallow alcohol - 18 EO 2 2 Alkyl phosphate 1 Dimerised oleic acid 2 - 2 Coconut ethanolamide Sodium tripolyphosphate 10 10 Sodium orthophosphate 8 8 Stabilising agent 3 Water 72 71 Obtained as Hostaphat Obtained as Empol, neutralised to the sodium salt in processing 3 Copolymer of maleic anhydride with vinyl methyl ether 1:1, obtained as Gantrez AN 119, hydrolysed and neutralised in processing The compositions of Examples 1 and 2 had low sudsing properties due to the alkyl phosphate or the dimerised fatty acid, and were suitable for use in front loading automatic washing machines. In these examples, the combined amount of sodium tripolyphosphate and sodium orthophosphate were equivalent in~hard water detergency building properties to a level of about 35% of sodium tripolyphospha~e alone, which of course is more than could be included into .
stable aqueous liquid detergen~ composition.

110~3~ C 792 (R) Examples 3 to 5 T~ree stable, heterogeneous built liquid detergent compositions were prepared to the following formulations:
Ingredient PercentageX
Ex 3 Ex 4 Ex 5 ( 13 15 2.5 2.5 2.5 Potassium alkylbenzene 1 sulphonate 6.5 6.5 6.5 Sodium tripolyphosphate 11.0 16.0 18.0 Potassium tripolyphosphate - - 3.0 Potassium orthophosphate 7.0 5.0 ~.0 Copolymer of maleic anhydride and vinyl methyl ether (1:1) 0.5 0.5 0.5 Dimerised oleic acid (K salt) 1 5.0 5 5.0 Sodium carboxymethylcellulose o.6 o.6 0.6 Sodium alkaline silicate 5.0 5.0 5.0 Fluorescent agents 0.3 0.3 0.3 Blue dye 0.02 0.02 0.02 Perfume o.3 0.3 0.3 Water to 100.0 tolOO.O tolOO.O
Calculated in acid form These compositions were prepared by firstly reacting the maleic anhydride copolymer with an equal amount of the nonionic detergent compound in water at 80C. Then more water was added with potassium hydroxide, followed by the alkyl benzene sulphonate and dimerised oleic acid which were neutralised by the potassium hydroxide. The remaining nonionic detergent compound and minor ingredients were then added, ~ollowed by the two phosphate salts and lastly 110~3~z C 792 (R) the silicate. The products of these Examples had ac~eptable viscosities of 450 cp, 700 and 950 cp at room temperature (Brookfield Spindle No. 3, 30 rpm), and they were all about pH 12.5 (undiluted). The detergencies of the compositions were determined in a Terg-O-Tometer at 50C and it was found that the compositions of Examples 4 and 5 were particularly good, being superior to a comparative product which contained 21% sodium tripolyphosphate, i.e. about the maximum level of that material which could be used in a stable aqueous liquid composition as the sole dete~gency builder.

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An aqueous, heterogeneous, stable liquid detergent composition comprising a) from 2-20% by weight of a detergent active material selected from the group consisting of anionic, non-ionic, amphoteric, zwitterionic synthetic detergents, soaps of C10-C22 fatty acids, soaps of dimerized C10-C22 fatty acids, and mixtures thereof;
b) at least 2% by weight of sodium tripolyphosphate;
c) at least 2% by weight of sodium or potassium ortho-phosphate, the sum of b) and c) being from 5-35% by weight;
d) 0.1-2% by weight of a copolymer of maleic anhydride with ethylene, styrene or vinylmethylether in an aqueous medium.

2. A composition according to claim 1, comprising 5-15%
of a);
at least 4% of b);
at least 4% of c), the sum of b) and c) being from 10-30% by weight;
and 0.3-1.5% of d).

3. A composition according to claim 1, wherein the weight ratio of b) and c) is from 10:1 to 1:10.

4. A composition according to claim 3, wherein the weight ratio of b) to e) is from 4:1 to 2:3.

5. A composition according to claim 4, wherein the weight ratio of b) to c) is from 3:1 to 1:1.

6. A composition accroding to claim 1, wherein the sodium tripolyphosphate contains more than 50% by weight of phase I sodium tripolyphosphate.

7. A composition according to claim 1, wherein the copolymer d) is a copolymer of maleic anhydride with vinyl-methylether in a molar ratio of 1:1.

8. A composition according to claim 1, further com-prising an alkaline buffer.