CA1125619A

CA1125619A - Medium density powdered detergent composition and process for making same

Info

Publication number: CA1125619A
Application number: CA345,537A
Authority: CA
Inventors: Cassandra E. Rodriguez; Herbert E. Bauer
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1979-02-15
Filing date: 1980-02-12
Publication date: 1982-06-15
Also published as: PH15525A

Abstract

C.680 ABSTRACT OF THE DISCLOSURE
This invention relates to a powdered laundry detergent composition, and method for making the same, comprising a narrowly defined range of tetrasodium or tetrapotassium pyro-phosphate and an alkali metal tripolyphosphate, in conjunction with a linear alkylaryl sulfonate and sodium silicate and optionally an alkali metal salt of a fatty acid, that can be spray dried to give a loose bulk density range of 0.40 to 0.50 grams/cc.

Description

- 2 - Co680 BACKGROUND OF THE INVENTI~N
.

Detergency as applied to the washing of fabrics not only involves the remGval of dirt, both particulate and oily, but also involves the utilization of a given amount of product for the specific purpose of accomplishing this task. This is especially so in powdered laundry detergent compositions whereby the consumer is instructed to follow a recommended dosage in the use of the powdered composition for the most desired results.
Recent phosphate legislation in the United States has had a significant impact and effect on the recommended use instruction of the amount of product for a given wash load.
For example, most states have set the maximum limit of phosphorous content at 7.0 grams for a given recommended use instruction, thereby forcing detergent manufacturers to pursue alternate courses of action in the manufacture of detergent products containing ph~sphorous. One approach has been to lower the phosphate content in the powdered products to be within the allowable phosphorous content for a given wash load. This however has resulted in a significant loss in product efficacy and performance~
Another course of action was to reformulate powdered phosphate-based detergent products to a drastically reduced total phosphate content with a corresponding increase in the use concentration of the product to obtain the maximum allowable 7.0 grams of phosphorous per recommended usage.
; This latter course of action resulted in a very significant drawback from a consumer standpoint, namely, (1) consumers were required to increase the amount of detergent previously used by a factor in the range of as much as twenty-five to fifty percent in order to achieve the same level of performance, and (2) that for the purchase a given volume of powder, the number of washes were significantly reduced. Additionally, both of these responses to a lowered maximum allowable phosphorous content per *`"

.

- 3 - C.680 recommended usage, result in an even greater loss in ef~icacy and performance for those consumers who customarily use about, or slightly less, one cup of powdered detergent regardless of recommended use instructions. Although this invention was prompted by the problems posed by a reduction in the allowable phosphorous content per detergent usage, it will be appreciated that the problem created by the aforementioned consumer habit of misuse will be operable under a broad range of formulation criteria.
Normally, the bulk density of commercial detergent powdered products is in the range of from about 0~28 to about 0.36 grams/cc, usually about 0.32 grams/cc.
Confronted with the problems outlined above, however, applicants have discovered that if a higher bulk density product could be provided to the consumer, that is, in the range of from 0.40 grams/cc to 0.50 grams/cc, the aforementioned deficiencies in powdered, phosphate-based products available to the consumer could be significantly reduced if not entirely overcome. This is accomplished with an anionic-surfactant-based detergent composition by i incorporating therein critical ratios of an alkali-metal tripolyphosphate and tetrasodium or tetrapotassium pyro-phosphate, along with an alkali-metal silicate, so that when the slurry composition is spray-dried, a powdered laundry detergent composition having a loose bulk density of 0.40 to 0.50 grams/cc is obtained. This results in powdered compositions which will give equal to or greater efficacy and performance with significantly less volume of ; 30 product being utilized by the consumer.

. .

- 4 - ' C.680 THE PRIOR ART

The following patents generally relate to detergent compositions with regard to one or more of the ingredients recited in the po~dered detergent composition set forth hereinafter, but are not within the scope of the present invention either as to the characteristics of the composition, its combined ingredients, or the benefits provided thereby.
US Patent 2,904,513 issued September 15, 1959;
US Patent 2,941,947 issued June 21, 1960;
: US Patent 2,992,186 issued July 11, 1961;
US Patent 3,174,934 issued March 23, 1965;
US Paten~ 3,574,121 issued April 6, 1971;
: US Patent 3,918,921 issued November 11, 1975;
US Patent 4,007,124 issued February 8, 19-77;
US Patent 2,947,701 issued A~l9Ust 2, 1960;
US Patent 2,925,390 issued February 16, 1960;
US Patent 2,897,155 issued July 28, 1959;
US Patent 3,133,024 issued May 12, 1964;
US Patent 3,242,091 issued Mcarch 22, 1966;
~S Patent 3,330,767 issued July 1l., 1967;
US Patent 3,303,136 issued February 7, 1967;
25 - US Patent 3,334,076 issued September 26, 1967;
US Patent 3,361,675 issued January 2, 1968;
US Patent 3,620,979 issued November 16, 1971;
US Patent 3,639,287 issued February 1, 1972;
US Patent 3,68~,723 issued August 15j 1972;
US Patent 3,775,348 issued November 27, 197.3;
US Patent 3,954,643 issued May 4, 1976;
:- US Patent 4,000,080 issued December 28, 1976;
US Patent 4,019,998 issued ~pril 26, 1977; and US Patent 4,102,823 issued July 25, . - ' ' .
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- 5 - C.680 SU~ IARY OF THE I~VENTION
-The present invention relates to a medium density, powdered laundry detergent composition comprising ~a) from about 10% to about 25% of a water-soluble : hydrocarbon compound having the general formula:
Rl - S03Ml wherein Rl is an alkylbenzene radical having from 8 to 18 carbon atoms in the alkyl group; and Ml is a cation of sodium or potassium;
(b) fro~ about 5% to about 30% by weight of an alkali : metal tripolyphosphate;
(c) from about 10% to about SQ% of tetra-sodium or - tetra-potassium pyrophosphate;
(d) from about 5% to about 20% by weight of a silicate having the formula SiO2:X2O wherein X is sodium or potassium, or mixtures thereof, and the molar ratio of SiO2:X2O is from about 1:1 to about 3.75:1;
(e) from 0~ to about 4% by weight of a sodium or potassium salt of a fatty acid;
(f) the balance of the composition being a filler;
.
the ratio of component (c) to component (b) being in the range of 1.5:1 to 3:1, and the lo.ose bulk densi~y of the powdered detergent composition being in the range of from 0.~0 grams/cc to 0.50 grams/cc.
.~ ~y the term "loose bulk density" is meant the weight per unit of a given volume of powder whereby the volume is filled with the free flowing powdered product with a minimum of compaction.
The invention also relates to a process for the :-preparation of a powdered laundry detergent composition comprising:
1. forming an agueous slurry of a water-soluble hydrocarbon compound having the general formula Rl - S03111 - .

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6 ~ ~3 ~ 6 - C.680 wherein Rl is an alkyl benzene radical having from 8 to 1~ carbon atoms in the alkyl group; and Ml is a cation of sodium or potassium; to give a final moisture content in the slurry in the range of from about 25% to about 35%, preferably from 28% to 32%;
2. heating the mixture formed in paragraph (1) to about a temperature of from about 100F to about 130F;
3. optionally adding to the aqueous slurry, at the elevated temperature, a mixture of NaOH or KOH and a fatty acid having from 10-1~ carbon atoms to form up to about 4%
by weight of a sodium or potassium salt of the fatty acid, in situ;
4. thereafter adding from about 5~ to about 20% by weight of a silicate having the formula SiO2:X2O, wherein X is sodium or potassium, or mixtures thereof, and the molar ratio of sio2:x2o is from about 1:1 to about 3.75:1; while maintaining the temperature from about 100F
to about 130F;
v 5. adding up to about 50% by weight of a filler;
6. adding from about 5% to about 30% by weight of an alkali metal tripolyphosphate;

7. raising the resulting mixture to a temperature~
of from about 150F to about 200F,

8. thereafter adding from about 10~ to about 50% by weight of tetra-sodium or tetra-potassium pyrophosphate with the proviso that the weight ratio of pyrophosphate to tripolyphosphate is from 1.5:1 to 3:1;

9. maintaining the total mixture at a temperature from about 180F to about 200F; and

10. spray-drying the total mixture to obtain a medium : density, powdered detergent composition having a loose bulk density of from 0.40 to 0.50 grams/cc;
the percentages and weight ratios expressed being based on the total weight of the powdered composition produced.
The preferred amounts of the ingredients, which are ' :
, ~ , . .
, - 7 - C.680 described below, are also included in the foregoing procedure for making up a preferred process according to the invention herein.
The moisture content of the product immediately following the spray drying operation will be from about 3%
to about 10%, preferably from 4~ to 8%, by weight as is basis. The final moisture content of the product will be conditioned to a large extent on the appearance of its powdered form, vi~ irregular clumps versus crisp, dry and free flowing, and of utmost importance, the loose bulk density.
~ he detergent surfactant according to the invention is an anionic, water-soluble hydrocarbon compound of the general formula:
Rl - SO3Ml wherein ~1 is an alkyl benzene radical having from 8 to 18 carbon atoms, preferably 12 to 16, and desirably 13 to 15 carbon atoms, in the alkyl group; and Ml is a cation of sodium or potassium. This component of the detergent composition is present in an amount of from about 10~ to about 25% by weight based on the total weight of the formulation, preferably from aboul: 14% to about 18% by weight. Typical examples of these anionic surface active agents are sodium or potassium al}cyl benzene sulfonates, eg sodium dodecyl benzene sulfonate, and sodium tridecyl benzene sulfonate;
The alkali-metal tripolyphosphate is present in the ` composition from about 5% to about 3% by weight based on the total weight of the final composition, preferably fro~
about 10% to about 20% by weight. Preferred examples are the sodium or potassium tripolyphosphates, or mixtures thereof.
The tetra-sodium or tetra-potassium pyrophosphate is present in the composition from about 10% by weight to about 50% by weight, preferably from about 15% to about 30%
by weight. Mixtures of the tetra-sodium or tetra-potassium ~'' `~ .
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8 - C.680 pyrophosphates may also be employed.
The presence of the tripolyphosphate and pyrophosphate are critical to each other for the purposes of obtaining an anionic-sulfonate based, powdered detergent composition S having the desired density range set forth herein. As such, the ratio of pyrophosphate to tripolyphosphate is critical and should be in the range of 1.5:1 to 3:1, preferably 1.75:1 to 2:25, and most desirably about 2:1.
The pyrophosphate/tripolyphosphate presence, in their deflned ratios, enables the anionic-sulfonate based composition to be spray dried so as to give a powdered detergent composition having the desired bulk density range. Moreover, the processing difficuities normally encountered with the spray drying of alkyl benzene sulfonates and tripolyphosphate, eg higher viscosity slurries re~uiring higher slurry moisture for purposes of fluidity and handling, lower productivity and bulk densities due to higher evaporative loads, are overcome.
The alkali metal silicate of the detergent composition is one which has the Eormula SiO2:M20 wherein M is an `
alkali metal, such as sodium or potassium, preferably sodium, or mixtures thereof. The molar ratio of SiO2:M20 is from about 1:1 to about: 3.75:1, preferably 1:1 to about 3.6:1, and desirably, 2.0:1 to 3.22:1. The alkali metal silicate is present in the slurry in an amount of from about 5% to about 20~, preferably from about 0% to about 17.5~, based on the total weight of the composition formed.
Water-soluble salts of the higher fatty acids, that is, soaps, may optionally be included in the composition according to the invention in an amount of up to about 4%
by weight, ie, 0~ to about 4~, preferably from about 1% to about 3% by weight. This component of the composition includes the alkali-metal soaps such as the sodium and potassium salts of higher fatty acids containing from about 8 to about 24 carbon atoms. Soaps are generally made by .~

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- 9 - ` C.680 the direct saponification of the fats and oils prior to use in the slurry preparation or by in situ neutralization of free fatty acids. Particularly desirable soaps for the composition having the desired density are the sodium and potassium salts of fatty acids derived from coconut oil and/or tallow, ie., sodium or potassium tallow and coconut soap.
The detergent composition according to the instant invention also contains a filler compound that is added to the slurry before spray drying. 1'he filler compound is present to balance the remainder of the composition to 100%. Usually the filler is present in an amount up to about 50~, preferably from about 20% to about 40% by weight, based on the total weight of the powdered composition. Many filler compounds are known in the art, the preferred compounds being sodium carbonate or sodium sulphate, or mixtures thereof. The function of the filler serves to balance the detergent composition to provide desired powder characteristics. Other ingredients can be added or used in admixture with the filler compound, and include the natural and synthetic clays, alkali metal carbonates, including calcium carbonate, bicarbo~latesr sesquicarbonates, borates, perborates, sulfates, chlorides, bisulfates and aluminates.
Other builders which can be used satisfactorily in minor amounts include the water-soluble salts of mellitic acid, citric acid, pyromellitic acid, benzene pentacarboxylic acid, oxydiacetic acid, carboxymethyloxysuccinic acid, and oxydisuccinic acid.
The amount of additional builder compounds that may be present in the composition according to the instant invention is about 5~ to about 30%, preferably from about 10 to about 20~ by weight. These additional builder compounds may be added to the aqueous slurry or admixed 3S with the dried product after the slurry composition is spray dried.

- 10 - C.680 The medium density powdered detergent composition of the present invention may be supplemented by additional detergent components, either by including them in the aqueous slurry to be spray dried, or by admixing such components with the composition following spray drying.
Soil suspending agents in an amount of from about 0.1 to about 5~ by weight, based on the total weight of the composition, such as water soluble salts of carboxymethylcellulose, carboxy, hydroxymethylcellulose, copolymers of vinyl ether and maleic anhydride, and polyethylene glycols having a molecular weight of from about 400 to about 10,000, are common ingredients to be included in the invention. Preferably, sodium carboxymethylcellulose is used.
Dyes, pigments, optical brighteners and perfumes can also be added in varying amounts as desired. Suitable bleaches would include percarbonates, perborates, and activators therefor.
Other materials such as fluorescers, antiseptic germicides, enzymes in minor amounts, anti-caking agents such as sodium sulfosuccinate and sodium benzoate, may also be added.
The medium density compositions of the present invention are desirably used in the washing operation at a concentration of about 0.15~ and at a wash temperature in the range of from 50F to 130F.
The following detergent compositions were prepared by the process according to the invention herein.

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- 13 - C.680 The performance and detergency characteristics of the powdered detergent compos-ition according to the instant invention with various other powdered detergent products on the market, was measured after soiled cloths were washed and dried with each of the formulation composition A
through F in the following Tables. The cloths used were cotton/dacron (65~/35~) artificially soiled with a particulate/oily soil and cloths with particulate clay-type soil. These fa~rics were washed at a temperature of 70F
10and 120F at an equivalent product usage of 0.9 cups per 17 gallons of wash water, which corresponds to a normal water level setting in a Kenmore clothes washing machine Model No 70. Fabrics were also washed with a water hardness level of 60 ppm and 180 ppm.
15After the fabrics were washed at the above-noted conditions, measurements were made on a light reflectance meter, Gardner Model No XL-10 and recorded as reflectance units. These measurements are itemized in Tables 1 through 4. The light reflectance was also measured after the fabrics were washed with the same Eormulation compositions B through F by increasing the volume usage, that is, the volume product was increased and compared with 0.9 cups of the product according to the instant invention (Formulation ; A). The loose bulk density of the product according to the instant invention, identified as Formulation A in the following tables, was 0.42 grams/cc. The higher the reflectance unit value, the cleaner the cloth and hence the greater the cleaning efficacy of the formula composition.

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- 14 - ~ C.680 Table 1 c . = = .
Cleaning of cotton/dacron (65/35) cloth at 70F soiled with particulate/oily soil Percent Weight 5 Ingredient A. s C D E E

Sodium linear 10 C18 alkyl benzene sulfonate 16.016.0 7.315.416.9 13.9 Fatty alcohol ethylene oxide condensate 1.10.90.9 0.4 15 Primary C14-C18 alcohol 3.9 avg ethylene oxide sulfate ~ 3.1 ., PrimarY C12-C20 ; . alcohol sulfate 7.0 i . Sodium tripoly-~ ~ phosphate10.025.0 25.631.029.4 25.5 : 25 . Tetra-sodium pyrophosphate20.0 SiO2 :Na20 ~2.4:1) 12.0 ~.0 11.17.99.4 7.8 Sodium salt of C12 C18 fatty acid 3.0 `- 35 ; Sodium sulphate33.6 42.6 35.6 33.0 24.0 38.5 ~r ~ .

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15 - C.680 Sodium carbonate 1.6 1.9 2.4 3.0 Miscellaneous to to to to to to 100%100% 100% 100%100% 100%
Volume usage (cup) 0.9 0.9 0.90-9 0-9 0-9 Reflectance Units at water hardness of 6Q ppm 58.253.8 51.1 57O456.456.9 at water hardness of 180 ppm - 54.142.0 45.2 50.051.547.6 Volume usage (cup) 0.9 1.25 1.251.0 1.0 1.0 -P~eflectance Units at water hardness of 60 ppm 58.255,4 55,1 57.556.058.3 at water hardness of 180 ppm 54.1 38.8 33.050.352.0 49.4 ;`' . , , - 16 - ~ C.680 Table 2 ~ . = _ Cleaning of cotton/dacron (65/35) cloth at 120F soiled with particulate/oily soil _____ Percent Wei~ht 5 Ingredient A B C D E F

Sodium linear C10 C18 alkyl benzene sulfonate 1.60 16.07.315.4 16.3 13.9 Fatty alcohol ethylene oxide condensate 1.10.9 0.9 0.4 15 Primary Cl~-C18 alcohol 3.9 av~ -ethylene oxide sulfate ~-3.1 Primary C12-C20 alcohol sulfate '7.0 '.
Sodium tripoly-phosphate 10.0 25.025.631.029.4 25.5 Tetra-sodium pyrophosphate 20.0 ~' SiO2 :Na20 (2.4:1) 12.0 8.0 11.17.9 9.4 7.8 .
Sodium salt of C12 C18 fatty acid 3.0 Sodium sulfate 33.6 42.635.6 33.0 24.0 38.5 .

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~, . ' ' ' ~' ~ ' - 17 - ~ C.680 Sodium carbonate 1.6 1.9 2.4 3.0 Miscellaneous to to to to to to 100%100% 100% 100% 100% 100 Volume usage ~cup)0.9 0.9 0.9 0.9 0.9 0.9 Reflectance Units .
at water hardness of 60 ppm 59.757.0 56.360.057.858.6 . . at water hardness of 180 ppm 58.444.4 50.655.755.252.3 Volume usage (cup)0.9 1.25 1.251.01.0 1.0 Reflectance Units at water hardness of 60 ppm 59.757.8 58.860.158.759.5 at water hardness of 18~ pp- 58.451.8 55.356.957.454.4 .

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- 18 - C.680 Table 3 Cleaning of cotton/dacron (65/35) cloth soiled with particulate clay-t~pe soil at 70F
Percent Weight 5 Ingredient A B C D E F

Sodium linear 10 C18 alkyl benzene sulfonate 16.0 16.0 7.315.416.913.9 Fatty alcohol ethylene oxide condensate 1.10.90.9 0O4 `~15 PrimarY C14-C18 alcohol 3.9 avg ethylene oxide sulfate 3.1 ;~2.0 PrimarY C12-C20 `alcohol sulfate 7.0 ., ~
Sodium tripoly-phosphate 10.0 25.0 25.631.029.425.5 . 25 Tetra-sodium pyrophosphate 20.0 ~-~, .
.SiO2 :Na20 30. (2.4:1) 12.0 8.011.17.9 9O4 7.8 ` Sodium salt of C12-C18 fatty .
acid 3.0 Sodium sulphate33.642.6 35.633.024.038.5 : ' ~r .
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- 19 - C.680 Sodium carbonate 1.6 1.9 2.4 3.0 Miscellaneous to to to to to to 100%100~ 100% 100%100~ 100%
Volume usage (cup)0.9 0.9 0.9 0.9 0.9 0.9 Reflectance Units 10 at water hardness of 60 ppm 73.470.1 72.5 72.871.2 72.1 at water hardness of 180 ppm 66.059.4 65.4 61.962.0 61.3 Volume usage (cup) 0.9 1.25 1.25 1.0 1.0 1.0 ~ Reflectance Units : . 20 at water hardness of 60 ppm 73.472.2 73.372.6 73.3 at water hardness of 180 ppm 66.060.6 63.063.2 61.5 : ,~, ' .

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- 20 - C.680 Table 4 Cleaning of cotton/dacron (65/35) cloth soiled with particulate clay-type soil at 120F
Percent Weight 5 Ingredient A B C D E F

Sodium linear C10-C18 alkyl benzene sulfonate 16.016.07.3 15.4 16.9 13.9 Fatty alcohol ethylene oxide condensate 1.1 0.9 0.9 0.4 , 15 PrimarY C14-C18 alcohol 3.9 avg ethylene oxide sulfate ` 3.1 20 Primary Cl2-c20 alcohol sulfate 7.0 Sodium tripoly-phosphate 10.025.025.6 31.0 29.4 25.5 Tetra-sodium pyrophospha~e 20.0 SiO2 :Nâ20 : 30 (2.4:1) 12.0 8.011.1 7.9 9.4 7.8 . . .
Sodium salt of C12-ClB fatty acid 3.0 Sodium sulphate 33.642.6 35.6 33.0 24.0 38.5 .;': .

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Volume usage (cup) 0.9 0.9 0.9 0.9 0.9 0.9 .

Reflectance Units at water hardness of 60'ppm 77.3 74.3 74.6 7.7.8 75.8 76.3 at water hardness of 180 ppm 73.2 60.8 67.0 68.9 67.6 64.3 Volume usage (cup) 0.9 1.25~ 1.25 1.0 1.0 1.0 Reflectance Units at water hardness of 60 ppm 77.3 75.8 7'7.0 78.2 76.8 76.5 at water hardness of 180 ppm 73.2 64.0 71.7 71.1 70.8 66.1 ' :
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Claims

- 22 - C.680 THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A medium density, powdered laundry detergent composition comprising (a) from about 10% to about 25% of a water-soluble hydrocarbon compound having the general formula:

wherein R1 is an alkylbenzene radical having from 8 to 18 carbon atoms in the alkyl group; and M1 is a cation of sodium or potassium;
(b) from about 5% to about 30% by weight of an alkalu metal tripolyphosphate;
(c) from about 10% to about 45% of tetra-sodium or tetra-potassium pyrophosphate;
(d) from about 5% to about 20% by weight of a silicate having the formula SiO2:X2O wherein X is sodium or potassium, or mixtures thereof, and the major ratio of SiO2:X2O is from 1:1 to about 3.75:1;
(e) from 0% to 4% by weight of a sodium or potassium salt of a fatty acid;
(f) the balance of the composition being a filler;
the ratio of component (c) to component (b) being in the range of 1.5:1 to 3:1, and the loose bulk density of the powdered detergent composition being in the range of from 0.40 grams/cc to 0.50 grams/cc.

2. The composition defined in claim 1 wherein R1 is an alkylbenzene radical having from 13 to 15 carbon atoms in the alykl group.

3. The composition defined in claim 2 wherein M1 is sodium.

4. The composition defined in claim 2 wherein M1 is potassium.

- 23 - C.680

5. The composition defined in claim 1 wherein component (a) is present in an amount of from about 14% to about 18%
by weight.

6. The composition defined in claim 1 wherein the alkali metal of component (b) is sodium.

7. The composition defined in claim 1 wherein the alkali metal of component (b) is potassium.

8. The composition defined in claim 1 wherein the ratio of component (c) to component (b) is from 1.5:1 to 3:1.

9. The composition defined in claim 1 wherein the ratio of component (c) to component (b) is from 1.75:1 to 2.25:1.

10. The composition defined in claim 1 wherein the fatty acid contains 8 to 24 carbon atoms and is present from about 1% to about 3% by weight.

11. The composition defined in claim 10 wherein the fatty acid salt is the sodium salt of coconut fatty acid or tallow fatty acid.

12. The composition defined in claim 1 wherein the filler is sodium sulfate or sodium carbonate.

13. The composition defined in claim 12 wherein the filler is present is an amount of from about 20% to about 40% by weight.

14. The composition defined in claim 1 wherein the loose bulk density is in the range of from 0.41 grams/cc to 0.45 grams/cc.

- 24 - C.680

15. A medium density, powdered laundry detergent composition comprising (a) from about 10% to about 25% of a water-soluble hydrocarbon compound having the general formula:

wherein R1 is an alkylbenzene radical having from 8 to 18 carbon atoms in the alkyl group; and M1 is a cation of sodium or potassium;
(b) from about 10% to about 20% by weight of sodium or potassium tripolyphosphate;
(c) from about 15% to about 30% of tetra-sodium or tetra-potassium pyrophosphate;
(d) from about 5% to about 20% by weight of a silicate having the formula SiO2:X2O wherein X is sodium or potassium, or mixtures thereof, and the molar ratio of SiO2:X2O is from about 1:1 to about 3.75:1;
(e) from 1% to about 3% by weight of a sodium or potassium salt of a higher fatty acid containing about 8 to about 24 carbon atoms;
(f) the balance of the composition being from about 20% to about 40% by weight of sodium sulfate or sodium carbonate, or mixtures thereof;
the ratio component (c) to component (b) being in the range of 1.5:1 to 3:1, and the loose bulk density of the powdered detergent composition being in the range of from 0.40 grams/cc to 0.50 grams/cc.

16. A process for the preparation of a powdered laundry detergent composition comprising the steps of (a) forming an aqueous slurry of a water-soluble hydrocarbon compound having the general formula:

wherein R1 is an alkylbenzene radical having from 8 to 18 carbon atoms in the alkyl group; and M1 is a cation of sodium or potassium; to give a final - 25 - C.680 moisture content in the slurry in the range of from about 25% to about 35%;
(b) heating the mixture formed in paragraph (a) to a temperature of from about 100°F to about 130°F;
(c) adding to the aqueous slurry; at the elevated temperature, a mixture of NaOH or KOH and a fatty acid having from 10-18 carbon atoms to form up to about 4%
by weight of a sodium or potassium salt of the fatty acid, in situ;
(d) thereafter adding from about 5% to about 20% by weight of a silicate having the formula SiO2:X2O, wherein X is sodium or potassium, or mixtures thereof, and the molar ratio of SiO2:X2O is from about 1:1 to about 3.75:1; while maintaining the temperature from about 100°F to about 130°F;
(e) adding up to about 50% by weight of a filler compound;
(f) adding from about 5% to about 30% by weight of an alkali-metal tripolyphosphate;
(g) raising the resulting mixture to a temperature of from about 150°F to about 200°F;
(h) thereafter adding from about 10% to about 50% by weight of tetra-sodium or tetra-potassium pyrophosphate with the proviso that the weight ratio of pyrophosphate to tripolyphosphate is from 1.5:1 to 3:1;
(i) maintaining the total mixture at a temperature from about 180°F to about 200°F; and (j) spray-drying the total mixture to obtain a medium density, powdered detergent composition having a loose bulk density of from 0.40 to 0.50 grams/cc;
the percentages and weight ratios expressed being based on the total weight of the powdered composition produced.

- 26 - C.680

17. The process defined in claim 16 wherein step (c) comprises adding from about 1% to about 3% by weight of a sodium or potassium salt of a higher fatty acid containing from about 8 to about 24 carbon atoms.