US 2864770 A
Description (OCR text may contain errors)
LIQUID DETERGENT COMPOSITION Homer W. McCune, Wyoming, and Oscar T. Quimby, Cincinnati, (Ithio, assignors to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio No Drawing. Application October 3, 1 956 Serial No. 613,604
8 Claims. (Cl. 252138) This invention is directed at the provision of a heavy duty built detergent in liquid form which will pour from a container.
An object of the invention is to provide a concentrated liquid detergent such that the sudsing and detergent performance of a 20 ounce carton of heavy duty synthetic detergent granules may be substantially achieved in a pint container of the liquid detergent.
A further object is to provide a liquid detergent which contains the inhibitors of corrosion and tarnish custom.- arily found in granular detergents.
The liquid synthetic detergents of the prior art are aqueous or aqueous-alcoholic solutions. When water is used to dissolve or disperse the detergent material, the most desirable calcium sequestering phosphate, sodium tripolyphosphate, is difficult to use because of its tendency to hydrolyze, forming pyrophosphate and orthophosphate.
The rupture of the P-O-P linkage in this hydrolysis results in the formation of acid phosphates,'hence, the pH of the solution falls and hydrolysis accelerates. This tendency may be repressed by bufiering to keep the pH at about 10, but in most cases the buffering causes more problems than it solves. Thus, it is difiicult to maintain a tripolypho-sphate solution or dispersion at the optimum pH for detergency, if the solvent or suspending medium contains water in amount sufficient to allow for'tripolyphosphate hydrolysis.
It is an object of this invention to provide a liquid detergent that contains a hydrolyzable phosphate.
It is a further object to provide a liquid detergent that contains more of the phosphate builders than can be provided in a solution type liquid detergent.
We'have found that if we use as the solvent and dispersing agent essentially non-aqueous water-soluble materials such as the glycols and glycerol we can prepare 'a heavy duty liquid detergent that will achieve the objectives stated. The term liquid as used herein and in the claims, will be used to define a material which has a continuous liquid phase, although finely divided solids are present therein, and which is pourable thru a inch orifice, at least after shaking, as will be hereinafter explained. The liquid detergent of our invention 'contains the active organic synthetic anionic detergent in solution, the phosphate builder in suspension, and the anti-.corroding additive commonly found in heavy 'duty granular detergents. The latter, commonly a silicate,.
maybe in suspension, or solution, or in both states.
The choiceof a suitable solvent and dispersing agent, for convenience called the vehicle, is not'sufiicient in itself to insure a satisfactory liquid heavy duty detergent. The-solubility of the anionic organic detergent is important. it should be completely soluble in the vehicle, or substantially completely insoluble. For the heavy duty liquid detergents, it is preferable to have the anionic organic detergent completely soluble, as the builders in suspension thicken the suspensions enough by themselves.
We have found that When the anionic synthetic detergent used is not completely soluble in the vehicle, the crystals Patented Dec. 16, 1958 of the anionic synthetic detergent dispersed in the vehicle will grow and produce coarse particles that tend to stifien the product so that it becomes unpourable. The vehicle, then, must have good solvent properties for anionic synthetic detergents, and the anionic synthetic detergent must be of a type having good solubility in such vehicles.
The suspensions of our invention are thixotropic. A thixotropic suspension is one that becomes thinner in consistency as it is stirred. Reversing the definition, a thixotropic suspension becomes stiffer upon standing. In our products the ideal situation is one in which the product is a gel when allowed to stand, but becomes pourable upon being given the slight agitation caused by picking up the container and tilting it for pouring. exact degree of thixotropy is difficult to obtain, but our compositions have enough rigidity at rest to prevent settling of the suspended builders, and become pourable with a moderate amount of shaking.
A thixotropic suspension stifiens upon standing because of forces acting between the surfaces of the suspended particles. This requires a large number of particles of a small size. The particles must be small, otherwise the in between forces will not be strong enough to overcome the force of gravity. In aqueous suspensions the optimum size is said by some authorities (Thixotropy, by H. Fruendlich, published by Hermann & Cie, Paris, 1935) to be about 2-3 microns. With a viscous vehicle like glycerol and glycol, and with a density greater than 1, the particle szies may be greater. If all of the particles are approximately the same size, our compositions will be stable at a particle size of about 5 microns. Particle sizes may be determined by microscopic examination, the average particle diameter being determined by observation against a ruled grating.
Example 1.-The builder used in this preparation was Victamide, described by the manufacturer as an ammonium salt of an amide polyphosphate. A method of manufacturing this product is described in U. S. Letters Patent 2,122,122, issued to W. H. Woodstock. The manu- The preparation was available in particle size of 4-6 microns and was received in this size from the Victor Chemical Works. The density was 1.83 gm./cm.
15 parts of sodium polypropylene benzene sulfonate, in which the polypropylene averages about 12 carbons, purified by dissolving in alcohol, filtering off insoluble impurities, and driving off the solvent, were dissolved in 35 parts of ethylene glycol. There was then added 50 parts of Victamide of average particle size of 5 microns. This was then passed three times thru a revolving cone colloid mill. The cream from the mill was subjected to a vacuum and the air removed. The air-free suspension did not show any settling after 1 week. This preparation has a tendency to become too viscous to pour upon more prolonged standing. Its utility is therefore limited to situations where its time of use is within a few weeks or so of its preparation.
We have found that we can make stable thixotrop1c suspensions of phosphate builders if a part of the suspended-phosphate is very time, 0.5 micron or less, i. e.
colloidal, the remainder being of larger particle size. The stable suspensionsmay'be made in which only /6 oithe phosphate builder is of colloidal size, the remainder being about 25 to 30 microns in size. In terms This of sound economic practice, the preferred range of particle size is that in which less than half of the phosphateis colloidal (0.5 micron or less) and the remainder is commercially ground phosphate of about 25 micron size.
The holdup of large particles by small ones makes it possible to make a thixotropic suspension with part of the builder, and this suspension will then hold up relatively large particles of additional builder which may be chemically the same or different.
Example 2.-Sodium tripolyphosphate, hexahydrate was prepared in size of the order'of 0.5 micron in the following manner.
A solution of 12 parts, by weight, of sodium tripolyphosphate in 100 parts, by weight of water, was pre pared. This solution was diluted with twice its volume of formamide, and mixed thoroughly. The mixture was poured into an amount of 3A denatured alcohol equal to 7 times the volume of the sodium tripolyphosphate solution. A very fine precipitate of sodium tripolyphosphate, hexahydrate was formed. After standing 3 days the fine particles had digested into coarser particle'size averaging 0.5 micron.
13 parts of sodium polypropylene benzene sulfonate freed from salts as shown in Example 1 were dissolved in 35.5 parts of ethylene glycol to which 3 parts of water had been added. To this solution was added 8.5 parts of sodium tripolyphosphate, hexahydrate of 0.5 micron size as prepared above. To this was added 40 parts of sodium tripolyphosphate of 9 micron size. The preparation was put thru the revolving cone colloid mill three times and freed from air by evacuation.
This liquid detergent product practically had no tendency to settle, and had a desirable thixotropic property.
The suspension of this invention should not settle more than is indicated by about the top 5% of a column becoming clear in 4 weeks. Using the No. 4 spindle in the Brookfield synchroelectric viscosimeter, the viscosity at 60 R. P. M. is about /3 that of the viscosity at 6 R. P. M.
Example 3.Middle cut coconut alcohol containing about 65% of alcohol with 12 carbon atoms was reacted with 3 moles of ethylene oxide and the reaction product sulfated with chlorosulfonic acid, and neutralized with sodium hydroxide. For convenience this reaction product is called C,,(EtO) S.
14.5 parts of C,,(EtO) S was dissolved in 30.4 parts of ethylene glycol and to this there was added 16 parts of sodium tripolyphosphate of 0.1 micron size and 8.1 parts of sodium tripolyphosphate of the commercially ground particle size of 25 to 30 microns, 9.6 parts of sodium silicate of SiO /Na O ratio of 3:4, containing 2.9 parts of water, and 15.6 parts of sodium sulfate. The sodium sulfate wasconsidered as a filler and this example showed it to be usable. To this, in mixing, was added 2.9 parts of C alcohol of 92% purity as a suds booster.
The finished mix had a viscosity of 65 poises with the No. 4 Brookfield spindle at 60 R. P. M., and showed no settling in 177 days. In this example the potassium salts of the polyphosphate may be used with equally good results.
A method of preparing the fine, about 0.1 micron size, sodium tripolyphosphate used in the above example is to dilute a solution of parts by weight of sodium tripolyphosphate in 100 parts, by weight of water, with 9 volumes of formamide, mix well and pour mix into 20 volumes (referred to the volume of the sodium tripolyphosphate solution as a unit) of 3A denatured alcohol. The fine precipitate is anhydrous sodium tripolyphosphate, phase II.
Example 4.A solvent mixture was prepared consisting of 15.2 parts of propylene glycol; 5.2 parts glycerine; 11.0 parts water. There was dispersed in this a sodium tripolyphosphate mixture consisting of 17.8- parts of fine particles of about 0.1 microns, in average diameter and- 15.2 parts of commercially ground sodium tripolyphosphate at a diameter averaging about to microns. There was then added 19.9 parts of C,,(EtO) S, 8.3 parts of silicate of soda of a SiO /Na O ratio of 3:2, and as a suds booster, 3.7% of 12 carbon straight chain alcohol of 92% purity. The 0.1 micron size tripolyphosphate is especially good as a suspending agent for this commercially ground, about 25 micron size, phosphate.
The propylene glycol-glycerine mix as a solvent has the advantage of providing low viscosity in the finished product. This preparation had a viscosity of 27 poises with a No. 4 Brookfield spindle at 60 R. P. M.
In this preparation there can be used sodium pyrophosphate of the same particle sizes as the tripolyphosphate, in place of the latter. In a co-pending application in the name of Joseph Blinka, Serial No. 614,293, filed October 5, 1956, and entitled Colloidal Phosphates, a novel method of making phosphate of 0.1 micron size is disclosed, and such materials may be used in whole or in part as the phosphate ingredients in the practice of this invention.
In order to equal the performance of a granular heavy duty detergent, the phosphate builder should be in the ratio of 1:1 to 4:1 to the anionic synthetic detergent. The phosphate builder is used as the alkali metal salt, i. e. sodium or potassium.
The products of our invention when mixed into water in a dishpan, laundry machine, or other washing vessel, dissolve rapidly to produce washing solutions capable of heavy duty performance.
The minimum ratio of synthetic anionic detergent to the water-soluble organic vehicle should be 1:3, and this detergent will constitute 10% to about 25% of the weight of the total composition, and enough to insure adequate heavy duty detergent performance. The preferred ranges in percent by weight are: vehicle 30 to anionic synthetic detergent 12 to 20%, and calcium sequestering phosphate or Victamide 24 to These preparations, with the synthetic anionic dis solved in the vehicle, can contain a water-soluble silicate as a corrosion inhibitor. Silicate may be added as a solution but this ordinarily adds too much water to the composition. It is not practical to have a completely anhydrous vehicle because of the hydroscopic character of the glycols and glycerine, but it is frequently desirable to minimize the water content. It is preferable to add dried granulated silicate, which may contain as much as 17% of water. The silicates of a SiO /Na O ratio of about 2:1 dissolve completely in the vehicle, if stirred for about 15 to 20 minutes. silicates of a ratio of SiO /Na O of 3.2 to 1' do not dissolve completely in the vehicle but the undis solved part is easily held in suspension by the thixotropic effect of the suspended phosphate. The amount of silicate solids should be about 15% of the phosphate. Coconut monoethanolamide, fatty alcohol and no-ther organic builders may be added and will remain in solution or as a dispersion with no difiiculties.
While the examples have been limited to the relatively inexpensive vehicle materials, ethylene glycol, propylene glycol, and glycerol, other materials can be used in their place. The three basic requirements for the suspending liquid are high solvent power for synthetic detergents, water solubility, and relatively high specific gravity. The high specific gravity helps keep the particles of builder in suspension. The suspending liquid should preferably have a specific gravity of greater than about 1. After the anionic organic synthetic is dissolved in the suspending liquid, the specific gravity will usually be greater than 1.05. The viscosity of the solution is important. If the solution of the anionic synthetic detergent in the water soluble organic liquid has a viscosity more than about 2 poises, the addition of the phosphate builder in the amounts previously set forth, in dispersed form, will produce an unpourable composition. If the viscosity of the solution'of anionic synthetic detergent in the water soluble organic liquid is below about 0.5 poise (50 centipoises) the dispersed phosphate is apt to settle out. While Examples 3 and 4 showed C,,(EtO) S as a suitable anionic detergent, the sulfated and neutralized reaction products of 2 or of 4 moles of ethylene oxide with 1 mole of middle cut coconut alcohol (containing about 65% of C alcohol) are of utility in preparing the compositions of our invention.
Among the substances which meet the criteria of high solvent power for synthetic detergents, water solubility, and density, in addition to the ethylene glycol, propylene glycol and glycerine are trimethylene glycol, and isobutylene glycol. Glycols with more than four carbon atoms in the molecule are not good solvents for the synthetic detergents, and not usable. Small amounts of water, such as that which may be present in the substantially anhydrous glycol vehicle or in the silicate can be tolerated. There may also be used as a vehicle material any of the liquid nonionic detergents, such as alkyl phenoxy polyoxyethylene ethanols, exemplified by Igepal CA 630, sold by the Antara Chem. Division of General Aniline and Film Corp. These materials, of course, contribute to the detergency, hence when they are used it may not be necessary to add-as much anionic synthetic detergent. Since the nonionics are not good sudsers some anionic synthetic detergent or an added suds builder is necessary if normal sudsing is desired. If low sudsing detergents are desired it may be desirable to have the vehicle contain substantial amounts of the nonionic detergent. If part of the vehicle is a liquid nonionic it should be miscible with the glycol-glycerol type making up the remainder of the vehicle. The vehicle should preferably contain not less than /3 of the glycol-glycerol type of material. The vehicle will normally constitute from about 25% to 50% of the whole composition. These percentages themselves are not critical, the viscosity of the complete composition is the limiting factor. The composition should be thin enough to pour through a opening at least after, shaking and it should be thick enough to hold the phosphate in suspension.
The anionic synthetic detergent used should be soluble in the vehicle to an amount that will allow the dissolved anionic synthetic to constitute at least of the total weight of the complete detergent and enough to insure that the complete detergent composition will have adequate heavy duty detergent properties.
Having thus described our invention, what we claim 1. A thixotropic liquid detergent consisting essentially of: 1) an organic vehicle, fully water soluble, with a specific gravity greater than about 1, said vehicle including not less than by weight of a member of the group consisting of glycols with not more than 4 carbon atoms in the molecule, glycerine and mixtures thereof; (2) a calcium sequestering phosphate substantially in soluble in said vehicle, said phosphate being in particulate form, at least about A; of the particles thereof, and suflicient to maintain a suspension in said vehicle settling not more than about 5% in four weeks, having a particle size not greater than about 0.5 micron, the remainder of said particles being no larger than about 25 microns, said phosphate being in ratio to the synthetic detergent of 1:1 to 4: 1; and (3) a detergent chosen from a class consisting of sulfated and sulfonated, anionic, non-soap, detergents fully soluble in said vehicle, said anionic synthetic detergent constituting at least 10% of the whole composition, and enough to achieve adequate heavy duty detergency, but not over 25 and the solution of anionic synthetic detergent in the vehicle having a viscosity in the range from about 0.5 to about 2.0 poises.
2. The composition of claim 1 in which the calcium sequestering phosphate is about 4 to 5 microns inparticle size.
3. The composition of claim 1 in which at least A; of the calcium sequestering phosphate is of a size of about 0.1 micron and the remainder of the calcium sequestering phosphate particles being no larger than about 25 microns in size.
4. The composition of claim 1 in which the vehicle is a mixture of propylene glycol and glycerine, said glycerine constituting not less than 10% nor more than 50% of the vehicle.
5. The composition of claim 1 in which the anionic synthetic detergent is the sulfated and neutralized prodnet of the reaction of about 3 moles of ethylene oxide with a straight chain alcohol containing at least about 65% C carbon atoms in the molecule.
6. The detergent composition of claim 1 in which the vehicle comprises about 25 to 50% of the composition, the anionic synthetic detergent constitutes about 10% to 25 of the composition and is in amount at least 6 by weight of said vehicle and the phosphate suspension is in the ratio of 1:1 to 4:1 to the synthetic detergent.
7. A thixotropic liquid detergent consisting essentially of: (l) a mixture of propylene glycol and glycerine in which the glycerine amounts to between 10% and 50% by weight, (2) a sulfated and neutralized reaction prodnot of 1 mole of fatty alcohol, containing at least 65 of C alcohol, with 2 to 4 moles of ethylene oxide per mole of fatty alcohol dissolved in said mixture of propylene glycol and glycerine, said reaction product being in amount of at least /3 of the amount of propylene glycol and glycerine, the solution of (2) in (1) having a viscosity in the range from about 0.5 toabout 2.0 poises; and (3) a colloidal dispersion of sodium tripolyphosphate in the solution of (2) above, in (1) above, said colloid dispersion containing at least /6 of the sodium tripolyphosphate in size not greater than 0.1 micron, and the remainder of the particles being so larger than about 25 microns, said dispersion of sodium tripolyphosphate being present in ratio to the sulfated and neutralized reaction product in ratios of 1:1 to 4:1.
8. A thixotropic liquid detergent consisting in parts by weight, essentially of (a) 31 parts to 35 parts of a mixture of propylene glycol and glycerine in which the glycerine amounts to 10 to 50%, (b) 13 to 20 parts of a detergent selected from a group consisting of sulfated and sulfonated anionic, non-soap, detergents, fully soluble in said mixture, the solution of (b) in (a) having a viscosity in the range from about 0.5 to about 2.0 poises, and (c) 24% to 50% of sodium tripolyphosphate dispersed in said solution, said phosphate being in particulate form, at least about A5 of the particles thereof, and suflicient to maintain a suspension in said vehicle not settling more than about 5% in four weeks, having a particle size not greater than about 0.5 micron, the remainder or said phopshate particles being no larger than about 25 microns.
References Cited in the file of this patent UNITED STATES PATENTS 2,581,677 Machlis Jan. 8, 1952 2,607,740 Vitale Aug. 19, 1952 2,615,847- Thompson Oct. 28, 1952 2,622,068 Hizer Dec. 16, 1952