CA1240228A - Liquid laundry detergent composition containing polyphosphate - Google Patents

Abstract

LIQUID LAUNDRY DETERGENT COMPOSITION
CONTAINING POLYPHOSPHATE

Abstract of the Disclosure:

A liquid heavy duty laundry detergent composition comprising a suspension of polyphosphate builder salt in liquid nonionic surfactant. To improve stability against settling on standing, the composition contains also a small amount of an acidic organic phosphorus compound having an acidic -POH group, such as a partial ester of phosphoric acid and an alkanol.

Description

lZ40~Z8 This invention relates to liquid laundry detergent composition.
Liquid non aqueous heavy duty laundry detergent compositions are well known in the art. For instance, compositions of that type may comprise a liquid non ionic surfactant in which are dispersed particles of a builder, such as a polyphosphate builder, as shown for instance in United States patents Nos. 4,316,812; 3,630,929; 4,264,466, and British patents Nos. 1,205,711 and 1,270,040.
It is known that such suspensions can be stabilized against settling by adding an inorganic insoluble thickening agent or dispersant of very high surface area such as finely divided silica of extremely fine particle size (e.g. of 5-100 millimicrons diameter such as sold under the name Aerosol) or the other highly voluminous inorganic carrier materials disclosed in United States Patent 3,630,929, or by including various clays, such as attapulgite, as disclosed in United States Patent 4,264,466. Grinding to very fine particle sizes also increases the stability.
In accordance with one aspect of the invention, there is provided a liquid heavy duty laundry detergent composition comprising a suspension of an alkali metal polyphosphate builder salt in a liquid non ionic surfactant said composition containing an organic phosphorus compound having an acidic -POX group which compound is present in effective amount to raise the yield value of said composition.
Thus, the stability of the suspension is increased by including therein an acidic organic phosphorus compound having an acidic - POW
group. This may be, for instance, a partial ester of phosphoric acid and an alcohol such as an alkanol which has a lipophilic character, having, for instance, more than 5 carbon atoms, e.g. 8 to 20 carbon atoms. It is found that as a result of the inclusion of quite small amounts of the acidic organic phosphorus compound the suspension becomes significantly more

- 2 stable against settling on standing but remains parboil Thus, as shown below, inclusion of the acidic phosphorus compound in-creases the yield value of the suspension, but decreases its plastic viscosity.
It 15 believed that the use of the acidic phosphorus compound may result in the formation of a high energy physical bond between the -POX portion of the molecule and the surfaces of the inorganic polyphosphate builder so that these surfaces take on an organic character and become more compatible with the non ionic surfactant.
The invention is particularly suitable for use with suspensions in which the particle size of the polyphosphate build-or is reduced tub below about lo microns.

The suspensions of the polyphosphate builder, such as sodium tripolyphosphate ("TOP") in the non ionic surfactant are found to behave, theologically, substantially according to the Caisson equation:

l/2 l/2 l/2 ' 112 +
is the shear rate, is the shear stress, is the yield stress (or yield value) and CO is the infinite shear rate plastic viscosity (which can be measured by determining the slope of the graph of the square root of the shear stress (as ordinate) vs. the square root of the shear rate. The yield value is the minimum shear stress below which no flow occurs (i.e., it corresponds to the intercept at the ordinate, at zero ~Z40Z28 shear rate, of the graph mentioned above). it is accordingly a criterion of stability. The plastic v16cosity is a measure of the flyability once the yield value has been overcome.
It is preferred that the yield value (measured at 25 C) be at least about 2 Pixels and (for pour ability and disk pens ability) not above about 8 Pascal, such as about 3 to 7 Pascal, more preferably about 4 Pascal.
For studying thus theological behavior, one should use a uniform, well defined shear rat viscometer (with either coaxial cylinders or cone-plate geometry) such as a ~heometrics remoter.
The suspensions are preferably prepared by grinding a mixture of non ionic surfactant, particles of polyphosphate builder salt and the acidic organic phosphorus compound in a mill which will break down the builds particles to diameters below about 10 microns. The builder salt will generally be sup-plied as much larger particles of above about 40 microns die- -meter, such as lo, 200 or 400 microns. If desired, the builder salt may be premixed with the acidic organic phosphorus come pound (e.g. by spraying the acidic compound, dispersed or disk solved in water or volatile organic solvent, onto the builder salt).
During grinding it is preferred that the proportion of solid ingredients be high enough (e.g. at least about 40% such as about SWISS that the solid particles are in contact with each other and are not substantially shielded Jo m one another by the non ionic surfactant liquid. Mills which employ grinding balls (ball mills or similar mobile grinding elements have given 12402;~8 good results. Thus, one may use a laboratory batch attritor having 8 mm diameter statute grinding balls. For larger scale work a continuously operating mill in which there are 1 mm or 1.5 em diameter grinding balls working in a very small gap between a stators and a rotor operating at a relatively high speed (e.g. a Cobalt mill) may be employed; when using such a mill it is desirable to pass the blend of non ionic surfactant and solids first through a mill which does not effect such fine grinding (e.g., a killed mill) to reduce the particle size to less than 100 microns (e.g. to about 40 microns), prior to the step of grinding to an average particle diameter below 10 microns in the continuous ball mill.
The following Example is given to illustrate this invention further:

EXAMPLE

A non aqueous heavy duty built liquid detergent come position is prepared by blending non ionic surfactant and sodium tripolyphosphate ("TOP") with other ingredients with and without an acidic organic phosphorus compound, as described below, and then grinding the blend in an attritor mill (to reduce the particle size of the suspended ingredients to less than 10 microns). The grinding conditions are identical in each case: grinding for hour in an attritor mill containing 8 mm diameter statute grinding balls. (Wieneroto*W-l.S attritor, charged with 2.5Kg of mixture).

* Trade Mark OOZE

A B C D

Proportion of acidic organic phosphorus compound (%) 0 0.1 0.2 0.3 Yield stress (Pascal) 0.3 1.6 3.2 5.6 Plastic viscosity (Pascal seconds) 1.1 1.0 1.0 0.9 The apparent viscosity at any shear rate can be calculated, using the Caisson equation and the relationship:
apparent viscosity equals shear stress divided by shear rate.
The acidic organic phosphorus compound in this En-ample is a partial ester of phosphoric acid and a C16 to C18 alkanol (Empiphos 5632 from Martian); it is made up of about 35% monster and 65% divester.
The composition contains the following ingredients in the proportions specified.
35% non ionic surfactant comprising a mixture of equal parts of;
(a) a relatively water soluble non ionic ~urfactant which forms a gel when mixed with water at 25 C specifically a C13 to C15 alkanol which has been alkoxylated to introduce 10 ethylene oxide and S propylene oxide units per alkanol unit and (b) a less water-soluble non ionic surfactant specie focally a C13 to C15 alkanol which has been alkoxylated to into-dupe 4 ethylene oxide and 7 propylene oxide units per alkanol unit.

~Z40228 12% of the reaction product prepared by mixing 100 g of succinic android with 522 go of the non ionic surfactant known as Dobanol 25-7 (the product of wthoxylation of a C12 to C15 alkanol, which product has about 7 ethylene oxide units per molecule of alkanol) and 0.1 g. of pardon (which acts so an esterification catalyst here); heating at 60C for 2 hours,;
cooling and filtering to remove unrequited succinic material (infrared analysis indicates that substantially all the free hydroxyls of the surfactant have reacted to form an acidic half ester in which the OH group of the non ionic surfactant has been esterified with one carboxyl group of the succinic android).
31~5% TOP in formulation A; owe in formulation B;
31.3% in C and 31~ 2% in D.
9% sodium perorate MindWrite, Nub H20.
4 5% tetraacetyl ethylene Damon; this is an activator for the sodium perorate 4% copolymer of about equal-moles of methacrylic acid and malefic android, completely neutralized to form the sodium salt thief (Cyclone CP5); this serves to inhibit incrustation (as from formation of dicalcium phosphate).
1% diethylene Damon pentamethylene phosphoric acid sodium salt; this is a sequestering agent agent having a high stability constant for complexation.
1% proteolytic enzyme slurry (it non ionic surfactant) (Espresso) 1% mix of pa carboxymethylcellulose and hydroxymethyl-cellulose (an antiredepoition agent) (Ralston DO 4050) lZ40ZZ8 0.5% perfume 0.5~ optical brightener of silbene 4 type) The TOP preferably is largely aiders material containing a small amount of TOP hexahydrate (e.g. an amount such that the chemically bound water content is about 3%, which corresponds to about one H20 per pentasodium Tripoli-phosphate molecule). Such TOP may be produced by treating an hydrous TOP with a limited amount of water. The presence of the hexahydrate slows down the rapid rate of solution of the TOP in the wash bath and inhibits caking. One suitable grade of TOP is sold under the name Thermphos NW; the particle size of this TOP as supplied is in the neighborhood of 400 microns, it phase I content it about 60%.
The mixture dispenses readily with cold water in the automatic washing machine. Its specific gravity is about 1.25 and it gives excellent washing when used at a dosage of about lo grams per wash load (as compared with 170 grams per wash lid Son the usual heavy duty laundry detergent powders) in conventional European home laundry machines (which employ about 20 liters of water for the washing bath.
The partial esters of phosphoric acid are known to act as foam suppressants and are mentioned for that purpose in US. patent 4,264,466 (Column 33, lines 34-45). The compositions of this Example are, however, of the low-foaming type; when used to wash conventional wash loads in typical European e.g., Germ man front-loading washing machines. They exhibit little foam even in the absence of the partial ester of phosphoric acid and thus do not require any foam suppressant.

124~228 The acidic organic phosphorus compound may be sol-acted from a wide variety of materials, in addition to the partial esters of phosphoric acid and alkanols mentioned above.
Thus, one may employ a partial ester of phosphoric or phosphorous acid with a moo or polyhydric alcohol such as hexylene glycol, ethylene glycol, dip or t'ri-ethylene glycol or higher polyethylene glycol, polypropylene glycol, glycerol, sorbitol, moo or dip glycerides of fatty acids, etc. in which one, two or more of the alcoholic I groups of the molecule may be esterified with the phosphorus acid. The alcohol may be a non ionic surfactant such as an ethoxylated or ethoxylated-propoxylated higher alkanol, higher alkyd phenol, or higher alkyd aside. The -POX group need not be bonded to the organic portion of the molecule through an ester linkage; instead it may be directly bonded to carbon (as in a phosphoric acid, such as a polystyrene in which some of the aromatic rings carry phosphoric acid or phosphinic acid groups, or an alkylphosphonic acid, such as propel or laurel-phosphoric acid) or may be connected to the carbon through other intervening linkages such as linkages through 0, S or N atoms).
Preferably, the carbon phosphorus atomic ratio in the organic phosphorus compound is at least 3:1, such as 5:1, 10:1, 20:1, 30:1 or 40:1. Among the suitable compounds are the Phosphate ester surfactants described and listed in Kirk-Othmer "Encyclo-podia of Chemical Technology 3rd Edition, Vol. 22 (1983) Pages 359 to 361.
The particular partial alkyd ester of phosphoric acid and the C16 to C18 alkanol, described in the foregoing Example, is a solid which generally swells, but does not dissolve in the i2'~228 non ionic surf act ant. It is supplied US a powder. In a pro-furred method, used in that example, the TOP is added last (after the other solid ingredients have been added to the fig-rid blend of non ionic surfactant and reaction product of sue-cynic android and non ionic surfactant) and the powder of partial alkyd ester of phosphoric acid is added just before the TOP. Acidic organic phosphorus compounds soluble in the non ionic surfactant may also be employed.
As is well known, the non ionic surfactants are char-acterized by the presence of an organic hydrophobic group and an organic hydrophilic group and are typically produced by the condensation of an organic alpha tic or alkyd aromatic hydra-phobic compound with ethylene oxide (hydrophilic in nature).
Practically any hydrophobic compound having a car boxy, hydra, amino or amino group with a free hydrogen attached to the nitrogen can be condensed with ethylene oxide or with the polyp hydration product thereof, polyethylene glycol, to form a non-ionic detergent. The length of the hydrophilic or polyoxy-ethylene chain can be readily adjusted to achieve the desired balance between the hydrophobic and hydrophilic groups. Typical suitable non ionic surfactants are those disclosed in US. pat-ens 4,316,812 and 3,630,929, as well as those described and listed in the discussion of non ionic surfactants in Kirk-Othmer "Encyclopedia of Chemical Technology", 3rd Edition, Vol. 22 (1983), Pages 360 to 379.
Non ionic surfactants often tend to form gels with limited amounts of cold water; this can sometimes interfere with the lZ~02Z8 complete dispensing of the composition from the usual dispenser found in conventional automatic home laundry machines used on Europe. To lower the golfing temperature, and thus promote easier dispensing, there may be included in the composition a carboxylic acid anti-gelling agent. A preferred type of agent of this type is a compound having a carboxy~ic moiety joined to the residue of a non ionic surfactant, e.g., a half ester of succinic acid or other dicarboxylic acid in which the Ox group of the non~onic surfactant has been esterified with one carboxyl group of the acid. This material is preferably in solution in non ionic surfactant.
The polyphosphate builder salt is preferably an alkali metal (e.g. pa or K) tripolyphosphate, pyrophosphate ego. twitter-sodium pyrophosphate) or hexamethaphosphate. It is preferred that these be largely in an hydrous form. Mixtures ox two or more different polyphosphates may be used. The polyphosphate may also be used in admixture with one or more other water-soluble deter-gent builders.
Among the suitable builders are inorganic and organic builder salts such as the phosphates, carbonates, silicates, phosphonates, polyhydroxysulfonates, polycarboxylates and the like. Typical suitable builders are those disclosed in US. pat-ens 4,316,812; 4,264,466; and 3,630,929.
Since, as indicated in the Example, the compositions of this invention may be used at relatively low dosage, it is desirable to supplement any phosphate or phosphate-forming builder (such as sodium tripolyphosphate) with an auxiliary builder such as polymeric carboxylic acid having high calcium binding capacity, in amount in the range, for instance, of about I~40228 1 to 10% of the composition, to inhibit incrustation which could otherwise be caused by formation of an insoluble calcium phosphate. Such auxiliary builders are well known in the art.
The composition preferably comprises a per oxygen bleaching agent. This may be a per oxygen compound, such as an alkali metal perorate, per carbonate or per phosphate; a portico-laxly suitable material is sodium perorate MindWrite. The per-oxygen compound is preferably used in admixture with an activator therefore Suitable activators are those disclosed in So pat-en 4,264,466 or in column 1 of US. patent 4,430,244. Polyp assaulted compounds are preferred activators; among these, come pounds such as tetraacetyl ethylene Damon ("TOED") and glucose pentaacetate are particularly preferred.
The activator usually interacts with the per oxygen compound to form a peroxyacid bleaching agent in the wash water.
It is preferred to include a sequestering agent of high completing power to inhibit any undesired reaction between such peroxyacid and hydrogen peroxide in the wash solution in the presence of metal ions. Such a sequestering agent is an organic compound which is able to form a complex with Queue ions, such that the stability constant (pi) of the complexation it equal to or great-or than 6, at 25C, in water of an ionic strength of Do milliliter, pry being conventionally defined by the formula: pK=-log K where R represent the equilibrium constant. Thus, for example, the pox values for complexation of copper ion with ETA and ETA at the stated conditions are 12.7 and 18.8, respectively. Suitable so-questering agents include the sodium salts of nitrilotriacetic -SWISS

acid (NAT); ethylene Damon tetraacetic acid (ETA); diethylene trillion pentaacetic acid (DETPA); diethylene thiamine pent-ethylene phosphoric acid DUMP and ethylene diamlne twitter-ethylene phosphoric acid (EDITEMPA).
Other ingredients which may be included in the come position are enzymes (e.g. pro teases, amylases or lapses or mixtures thereof), optical brighteners, anti redeposition agents, colorants (e.g. pigments or dyes) etc.
The composition may also contain an inorganic insole ruble thickening agent or dispersant ox very high surface area such as finely divided silica of extremely fine particle size (e.g. of 5-100 millimicrons diameter such as sold under the name Aerosol) or the other highly voluminous inorganic carrier materials disclosed in US. patent 3,630,929, in proportions of 0.1-10%, e.g. 1 to 5%. For best results it is preferable, how-ever, that compositions which form peroxyacids in the wash bath (e.g. compositions containing per oxygen compound and activator therefore be substantially free of such compounds and of other silicates; it has been found, for instance, that silica and silicates promote the undesired decomposition of the peroxyacid.
In addition, the use of these water-~nsoluble inorganic materials can present other problems in the system. No voluminous silica or chain structure type clay is needed in the practice of this invention sod the composition is preferably substantially free of such materials.
* Trade Mark ~2~0Z;~8 While in the preferred compositions the average part-tale size of the solids has been reduced to less than about 10 microns (e.g., typically only about 5-10% of the solids con-tent has a particle size above lo microns), the invention may also be applied to compositions which have not been so finely ground. It will be understood thaw finer grinding increases the stability of the composition against settling on standing;
according to Stokes law the smaller the particle size the lower the rate of sedimentation. By raising the yield value obtained with a given degree of grinding, the use of the acidic pros-chorus compound can make it possible to increase the stability of compositions in which the average particle diameter is say 15, 20, or 25 microns, as by using increased amounts of the acidic phosphorus compound to attain the desired yield value of at least about 2 Pascal.
In the compositions of the invention, typical propriety-ions of the ingredients are as follows:
Suspended detergent builder, within the range of about 10 to 60%, such as 20 to 50%, e.g., about 25 to 40%;
Liquid phase comprising non ionic surfactant (and, option-ally, dissolved carboxylic acid gel-inhibitor) within the range of about 30 to 70%, such as about 40 to 60%; this phase may also include a delineate such as a glycol, e.g.. polyethylene glycol ego., "PEG 400") or hexylene glycol.
; Carboxylic acid antigelling agent, an amount to supply in the range of about 0.5 to 10 parts (e.g., about 1 to 6 parts, such as about 2 to 5 parts) of -COO (M.~.45) per 100 parts of lZ~OZZ8 the blend o f such compound and the non ionic surfactant; typical-lye the amount of this anti-gelling agent is in the range of about 0.01 to 1 part per part of non ionic surfactant, such as about 0.05 to 0.6 part, e.g. about 0.2 to 0.5 part;
Per oxygen compound (such as sodium perorate moo-hydrate) in the range of about 2 to 15%, such as about 4 to lo;
Activator, in the Lange of about 1 to I such as about 3 to 6%;
Sequestering agent of high co~plexing power, in the singe of about to 3%, such as about to 2%;
Acidic organic -POX compound, in the range of Oily to 5%, such as about 0.05 to 2%, e.g., about 0.1 to 1%.
In this application all proportions are by weight us-less otherwise indicated. In the Examples atmospheric pressure is used unless otherwise indicated.
It is understood that the foregoing detailed de-ascription is merely by way of illustration and that variations may be made therein without departing from the spurt of the in-mention.

Claims (15)

1. A liquid heavy duty laundry detergent composition comprising a suspension of an alkali metal polyphosphate builder salt in a liquid nonionic surfactant said composition containg an organic phosphorus compound having an acidic -POH group which compound is present in effective amount to raise the yield value of said composition.

2. A composition as in Claim 1 in which said composition is substantially nonaqueous and has a yield value in the range of about 2 to 8.

3. A composition as in Cliam 1 in which said composition is of the low-foaming type even in the absence of said organic phosphorus compound.

4. A composition as in Claim 1 in which said poly-phosphate salt is sodium tripolyphosphate.

5. A composition as in Claim 1 in which the particle size of said suspended builder salt is less than about 10 microns.

6. A composition as in Claim 1 in which the C:P atomic ratio in said phosphorus compound is at least about 3:1.

7. A composition as in Claim 1 in which said organic phosphorus compound is a partial ester of an alkanol and phos-phoric acid.

8. A composition as in Claim 6 in which said alkanol is a higher alkanol.

9. A composition as in Claim 1 which has been pre-pared by grinding said suspension until the particle size of said suspended builder salt is less than about 10 microns.

10. A composition as in Claim 1 in which said com-position is substantially nonaqueous and contains a peroxygen bleach.

11. A composition as in Claim 10 in which said per-oxygen bleach comprises sodium perborate and an activator therefor.

12. A composition as in Claim 11 in which said acti-vator is tetraacetyl ethylene diamine.

13. A composition as in Claim 1 substantially free of silica and silicate thickening agent.

14. A composition as in Claim 1 substantially free of chain structure type clay.

15. A composition as in Claim 1 which contains a car-boxylic acid anti-gelling agent.