Powdered detergent compositions containing a calcium salt of an anionic surfactant

The present invention relates to an improved mechanically mixed, non-spray dried, built laundry detergent composition comprising the calcium salt of a non-soap, organic, anionic surface active agent, an ethoxylated alcohol nonionic surfactant, and an alkali metal salt of a phosphate sequesterant builder compound.

FIELD OF THE INVENTION 
This invention relates to mechanically mixed, non-spray dried, built, 
powdered laundry detergent compositions containing (a) a calcium salt of a 
non-soap, organic, anionic surfactant, in particular, the calcium alcohol 
sulfates, linear alkane sulfonates, olefin sulfonates, linear alkyl 
benzene sulfonates, and alcohol ethoxy (1-6EO) sulfates; (b) an 
ethoxylated alcohol nonionic surfactant; and (c) an alkali-metal salt of a 
phosphate sequesterant builder compound. The detergent compositions 
according to the invention possess good processing and detergency 
characteristics, and excellent cold water detergency performance. The 
composition may additionally include non-phosphorous sequestering builder 
compounds. 
BACKGROUND 
The preparation of powdered detergent formulations by mechanical mixing 
methods based on the sodium salt of anionic surfactants and certain 
nonionic surfactants in the past has generally led to poor powder 
processing characteristics of the detergent formulation. 
The poor processing characteristics of these detergent formulations have 
been due to a variety of reasons, among which, for example, is that an 
excessive amount of water is usually associated with the anionic component 
of the detergent formulation and the hygroscopic nature of the surfactants 
themselves. Also incompatability of the nonionic surfactant with the 
electrolyte or builder component of the formulation has led to "bleeding" 
of the nonionic surfactant into a separate phase on the surface of the 
solid particles. 
The importance of preparing these detergent formulations by mechanical 
means is becoming increasingly important because of the low energy 
requirements and cost savings that are realized as compared to other means 
of preparing anionic, nonionic, and mixed powdered detergent formulations 
known in the art. Previous attempts at overcoming the aforementioned 
problems have included the addition of processing aids, for example, 
clays, which act as absorbents for the organic components in the 
formulations (Netherlands Pat. No. 7,413,521). Applicant has surprisingly 
discovered, however, that a much better approach in overcoming the 
processing problems of these nonionic based, powdered detergent 
formulations is by the use of the calcium salts of non-soap organic, 
anionic detergent surfactants in the formulations. Unexpectedly, these 
calcium salts do not significantly lower the detergent properties of the 
powder formulations relative to the corresponding formulation utilizing 
the sodium salt of the anionic surfactant. 
The use of alkali metal salts of anionic surfactants in detergent 
compositions to improve the detergency benefits thereof has been cited in 
various publications known in the prior art. Examples of the prior art are 
as follows: 
U.S. Pat. Nos. 2,908,651 issued on Oct. 13, 1959; 2,691,636 issued on Oct. 
12, 1954; 2,766,212 issued on Oct. 9, 1956; 3,718,609 issued on Feb. 23, 
1973; 3,686,098 issued on Aug. 22, 1972; 2,437,253 issued on Mar. 9, 1948; 
and Australian Pat. No. 18/76 published July 21, 1976. 
Applicant has discovered, however, that the selection of the calcium salt 
of certain organic, synthetic, non-soap anionic surfactants in combination 
with a selected class of nonionic surfactants and the alkali metal salt of 
a phosphate sequestering builder compound, has a significant effect in the 
preparation of powdered detergent formulations by mechanical means, while 
at the same time increasing the cold water detergency of such formulations 
as well as maintaining the overall detergency properties thereof. The 
prior art fails to recognize the problems encountered with mechanically 
mixed, nonionic based detergent products, and how they may be overcome. It 
is an object of the present invention, therefore, to provide mechanically 
mixed, powdered detergent compositions in an efficient manner and which 
will overcome the problems known heretofore in their manufacture, while at 
the same time maintaining good detergency properties, especially in regard 
to cold water detergency performance. 
All percentages are expressed by weight unless otherwise specified. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention relates to the mechanically mixed, non-spray dried, 
powdered laundry detergent composition comprising as the essential 
ingredients: (a) from about 4% to about 20% of the calcium salt of a 
non-soap, organic anionic surfactant, in particular, the calcium alcohol 
sulfates, alcohol ethoxy (1-6EO units) sulfates, linear alkane sulfonates, 
olefin sulfonates and linear alkylbenzene sulfonates (LAS), or mixtures 
thereof; (b) from about 4% to about 20% of an ethoxylated alcohol nonionic 
surfactant; and (c) from about 5% to about 70% of an alkali-metal salt, 
preferably sodium or potassium, of a phosphate sequestering builder 
compound, in particular the tripolyphosphates and pyrophosphates, the 
percentages being based on the total weight of the composition. The 
detergent composition according to the invention possesses good processing 
and detergency characteristics, and excellent cold water detergency 
performance. The composition may additionally include weak, 
non-phosphorous sequestering builder compounds. 
Applicant has surprisingly and unexpectedly found that desireable effects 
could be obtained with a detergent formulation containing a calcium salt 
of a non-soap, organic anionic surfactant and an ethoxylated alcohol 
nonionic surfactant. This is especially true when it has been heretofore 
considered that calcium acts as a detriment to detergency, and that the 
calcium salt of an anionic surfactant generally has low solubility in an 
aqueous medium. While not desiring to be held to any particular theory, it 
is thought that the calcium salt of the anionic surfactant dissolves in 
the micelles of the nonionic surfactant. Thus, when the phosphate builder 
compound is present, the calcium ions in the solid lattice structure of 
the insoluble salt are much more difficult to remove than those calcium 
ions present in the aqueous double layer of the mixed anionic/nonionic 
micelle. In any event, these occurrences lead to an efficient softening of 
the water and efficient detergent properties for the wash solution. It 
should be noted that the processing characteristics of such a detergent 
formulation is further enhanced by the fact that the calcium salts of the 
anionic surfactants according to the invention are readily prepared since 
they are relatively insoluble in water and can be easily filtered from 
aqueous solutions. This is in contrast to the sodium salts of the 
respective surfactants which are generally hygroscopic and at the very 
least water soluble. As such they cannot be readily isolated in dry form 
except in admixture with large amounts of inorganic electrolyte salts. 
Of particular importance in the detergent composition is the calcium salt 
of the synthetic, organic, non-soap, anionic surfactant, in particular, 
the calcium alkyl sulfates, calcium linear alkane sulfonates (or paraffin 
sulfonates), the calcium olefin sulfonates, the calcium linear 
alkylbenzene sulfonates, and the calcium alcohol ethoxy (1-6EO units) 
sulfates. 
As part of the synthetic anionic class of compounds forming this component 
of the detergent composition, they include the calcium salts of organic 
sulfuric reaction products having in their molecular structure an alkyl 
group containing from about 8 to 22 carbon atoms and a sulfuric acid ester 
group. Examples of this group of synthetic detergents are the calcium 
alkyl sulfates, especially those obtained by sulfating the higher alcohols 
(C.sub.8 -C.sub.18 carbon atoms) produced by reducing the glycerides of 
tallow or coconut oil. 
Particularly good cold water detergency is acheived when the C.sub.12 
-C.sub.14 alkyl sulfates are used, especially the C.sub.14 alcohol 
sulfates 
The calcium alcohol ethoxy sulfates (or alkyl ether sulfates) have the 
formula RO(C.sub.2 H.sub.4 O).sub.x SO.sub.3 Ca wherein R is alkyl or 
alkenyl of about 10 to about 20 carbon atoms and x is 1 to 6, preferably 1 
to 3. These sulfates are condensation products of ethylene oxide and 
monohydric alcohols having about 10 to about 20 carbon atoms. The alcohols 
can be derived from fats, e.g., coconut oil or tallow, or can be 
synthetic. Lauryl alcohol and straight chain alcohols derived from tallow 
are preferred herein. Such alcohols are reacted with 1 to 6 molar 
proportions of ethylene oxide and the resulting mixture is sulfated and 
neutralized. 
Specific examples of the alcohol ethoxy sulfates include calcium sodium 
coconut alkyl ethylene glycol ether sulfate; calcium tallow alkyl 
triethylene glycol ether sulfate; calcium tallow alkyl hexaoxyethylene 
sulfate; calcium C.sub.14 -C.sub.16 alkyl glycol ether sulfate; and 
calcium C.sub.10 -C.sub.20 alkyl triethylene glycol ether sulfate. 
The preferred "olefin sulfonate" detergent mixtures utilizable herein 
comprise olefin sulfonates containing from about 10 to about 24 carbon 
atoms. Such materials can be produced by the sulfonation of 
.alpha.-olefins by means of uncomplexed sulfur trioxide followed by 
neutralization under conditions such that any sultones present are 
hydrolyzed to the corresponding hydroxy-alkane sulfonates. The 
.alpha.-olefin starting materials preferably have from 14 to 16 carbon 
atoms. The preferred .alpha.-olefin sulfonates are described in U.S. Pat. 
Nos. 3,332,880 and 4,040,988, incorporated herein by reference. 
The paraffin sulfonates included in the anionic class of surfactants are 
essentially linear and randomly distributed, and contain from 8 to 24 
carbon atoms, preferably 12 to 20, and desireably 14 to 18 carbon atoms in 
the alkyl radical. An example of a paraffin sulfonate is that which is 
available from Henckel and Cie under the tradename "Hostapur SAS-60" 
(Sodium C.sub.13 -C.sub.18 paraffin sulfonate). 
The amount of anionic surfactant in the form of the calcium salt present in 
the composition may vary from about 4% to about 20% although it is 
preferred that from 8% to about 12% be present. 
The nonionic surfactant component included in the composition in accordance 
with the invention is of the ethoxylated alcohol type having the following 
formula: 
EQU RO(C.sub.2 H.sub.4 O).sub.n H 
wherein R is an alkyl, alkenyl or alkaryl group having 8 to 20 carbon 
atoms, preferably 12 to 18 carbon atoms; and n is an integer from 4 to 30 
preferably from 4 to 15, and most desireably from 6 to 12. 
The nonionic surfactants that may be included are condensation products of 
a long chain ethylene oxide moiety with a primary alcohol, secondary 
alcohol or alkyl phenol. Thus, R is a straight or branched chain 
hydrocarbyl moiety derived from a primary or secondary alcohol containing 
8 to 20 carbon atoms, preferably 10 to 15 carbon atoms, or an alkyl 
pheonol-based moiety where the alkyl chain is straight or branched and 
contains 6 to 12 carbon atoms, preferably 6 to 9 carbon atoms. 
Illustrative nonionic surfactants having the desired characteristics for 
formulationg mechanically mixed, non-spray dried, powdered detergent 
compositions are available on the market under the tradename of "Neodol" 
products by Shell Oil Company; "Tergitol" products by Union Carbide 
Company; and "Alfol" products by Continental Oil Company. Specific 
examples include "Neodol 25-7" (linear C.sub.12 -C.sub.15 primary alcohol 
condensed with 7 moles of ethylene oxide per mole of alcohol); "Tergitol 
15-S-7" (random secondary C.sub.11 -C.sub.15 alcohol condensed with 7 
moles of ethylene oxide per mole of alcohol); and "Alfol 1416-6.5" 
(primary C.sub.14 -C.sub.16 alcohol condensed with 6.5 moles of ethylene 
oxide per mole of alcohol). 
The amount of nonionic surfactant present in the composition may range from 
about 4% to about 20%, preferably from 8% to 12%. From the standpoint of 
consistency and storage characteristics of the powdered formulations 
herein, it is desired to maintain the level of the anionic component 
greater than that of the nonionic component in the composition. A ratio of 
anionic to nonionic of 3:2 is preferred although a greater or lesser range 
may be used, for example, 2.5-4.0:2.0, depending upon the desired 
characteristics of the end product. This is not to say, however, that the 
level of nonionic may not exceed that of the anionic in the composition 
for the purposes of operability. 
The builder component of the invention is of the strong sequestering type, 
i.e., a phosphate sequesterant builder compound. These compounds include 
the alkali metal tripolyphosphates and pyrophosphates, or mixtures 
thereof. Sodium and potassium are the preferred alkali-metal salts. 
In addition to the phosphate sequestering type builder compounds, 
non-phosphorous, water-soluble sequestering builder compounds may be added 
to the composition as an adjunct thereto. For example, the alkali metal, 
ammonium and substituted ammonium polyacetates, carboxylates, 
polycarboxylates, and polydroxysulfonates are useful sequestering builders 
in the present compositions. Specific examples of the polyacetate and 
polycarboxylate builder salts include sodium, potassium, lithium, 
magnesium, ammonium, and substituted ammonium salts of ethylene diamine 
tetraccetic acid, nitrilotriacetic acid, oxydisuccinic acid, mellitic 
acid, benzene polycarboxylic acids, and carboxymethoxysuccinic acid, and 
citric acid. 
Highly preferred non-phosphorus sequestering builder materials herein 
include sodium citrate, sodium oxydisuccinate, sodium 
carboxymethoxysuccinate, sodium mellitate, sodium nitrilotriacetate, and 
sodium ethylene diamine tetraacetate and mixtures thereof. 
Other preferred non-phosphorous, sequestering builder compounds included 
herein are the polycarboxylate builders set forth in U.S. Pat. No. 
3,308,067 to Diehl, incorporated herein by reference. Examples of such 
materials include the water soluble salts of the homo- and co-polymers of 
aliphatic carboxylic acids such as maleic acid, itaconic acid, mesaconic 
acid, fumaric acid, aconitic acid, citraconic acid, methylenemalonic aicd, 
1,1,2,2-ethane tetracarboxylic acid, dihydroxy tartaric acid, and 
keto-malonic acid. 
Additional preferred non-phosphorous sequestering builder compounds herein 
include the water soluble salts, especially the sodium and potassium 
salts, of carboxymethyloxymalonate, cis-cyclohexanehexacarboxylate, 
cis-cyclopentanetetracarboxylate, and phloroglucinol trisulfonate. 
Other builder compounds include non-phosphorous, crystalline and amphorous 
zeolytes such as those described in Netherlands Pat. No. 7,511,455 
published Apr. 6, 1976, and in German Patent OLS No. 2,433,485 published 
Feb. 6, 1975, which patents are incorporated herein by reference. 
The amount of phosphate sequestering builder compound present in the 
detergent composition may generally range from about 5% to about 70% 
preferably from about 10% to about 60% and most desireably from about 25% 
to about 50%. When the non-phosphorous water-soluble sequestering builder 
compounds are added to the already present phosphate builder compound of 
the detergent composition, it is done so in an amount that will not exceed 
about 20%, and usually in the range from about 5% to about 15% depending 
on the nature and strength of the non-phosphorous sequestering builder 
compound used. 
Other materials which may be present in the detergent compositions of the 
invention are those conventionally present therein. Typical examples 
thereof include soil suspending agents, hydrotropes, corrosion inhibitors, 
dyes, perfumes, fillers, abrasives, optical brighteners, enzymes, suds 
boosters, suds depressants, germicides, anti-tarnishing agents, cationic 
detergents, softeners, chlorine releasing agents, buffers and the like. 
The balance of the detergent compositions is water. 
The granular detergent compositions herein may also optionally contain 
processing aids, e.g. sodium sulfate. When an anticorrosion agent is used, 
it is preferred to use the sodium silicates containing a SiO.sub.2 
:Na.sub.2 O ratio of about 1:1 to about 3:75:1, e.g. Ru silicate 
(SiO.sub.2 :Na.sub.2 O = 2.4:1) and Britesil H-24 (SiO.sub.2 :Na.sub.2 O = 
2.4:1). 
The relative effectiveness of the compositions of the present invention is 
determined by actual wash performance in varying degrees of water hardness 
conditions, and by the actual flow characteristics of the powdered 
composition after its manufacture. The consistencies and flow 
characteristics of the composition are measured in terms of the 
descriptions given in Table A listed below, with each described condition 
being rated as "acceptable", "borderline acceptable" and "not acceptable". 
Each of the examples that are present hereinafter are rated according to 
the designation assigned to each of the descriptions given in Table A. 
TABLE A 
______________________________________ 
Flow Characteristics Description 
______________________________________ 
* A - Dry free flowing; not dusty - A-1 free flowing nondusty 
slight wicking 
A-2 free flowing nondusty 
severe wicking 
* B - Dry free flowing; dusty 
*** C - Packed; waxy; does not flow 
** D - very slightly damp; initially packed; free flowing 
after slight rapping 
* E - Dry; initially packed; can be broken up 
* F - Slightly damp; free flowing 
*** G - Damp botton; initially packed; top free flowing 
*** H - Tacky, crumbly, granular: H-1 damp granular - high levels 
of Na.sub.2 SO.sub.4 are detrimental 
* I - free flowing but can absorb more water 
* J - Good, smooth powder; little dust 
*** K - Slurry 
* L - Slight lumping 
* M - Dusty free flowing bead 
** N - Dusty, tacky; partially free flowing bead; N-1 Dusty, 
tacky, partially free 
flowing; compressible 
* O - Very dusty; compressible 
* P - Dusty; compressible; P-1 good powder properties, but 
compressible 
*** Q - Very moist; not a powder 
*** R - Creepy with small lumps; pourable 
*** S - Clumped together 
* T - Dusty; mostly free flowing with bumps 
* U - Dry; free flowing; large lumps 
** V - Granular, free flowing; slightly damp 
** W - Very slightly damp, free flowing; granular 
* X - Dusty; free flowing; medium lumps 
*** Y - Lumpy, creepy; poor powder properties 
*** Z - Creepy; very tacky bead; compressible 
______________________________________ 
* - acceptable 
** - borderline acceptable 
*** - not acceptable. 
The mixing procedure and order of addition of the detergent components 
according to the present invention are as follows: All materials are 
blended in a standard "Kitchenaid" mixer (Model No. 4C) at a slow speed 
setting (No. 1 setting). The dry components are added to the mixer first 
and allowed to co-mingle for approximately five minutes. While the mixing 
takes place, the liquid components are added, with the non-ionic 
surfactant being added last. The total mixture is allowed to be mixed for 
approximately 10 additional minutes. The flow characteristics of the 
finished composition are then determined before the product is utilized in 
a wash. 
The cleansing ability or detergency of the detergent formulations are 
determined with a Terg-O-Tometer. In the testing of the examples that 
follow, the four pots of the Terg-O-Tometer are first filled with 1000 ml 
of water of the desired hardness (e.g. 60 ppm, 120 ppm or 240 ppm, 
calculated as calcium carbonate; 2:1 Ca.sup.++ /Mg.sup.++) at the desired 
temperature (e.g. 120.degree. F. or 80.degree. F.). Next, 1.0 or 2.0 grams 
each of four test formulations are dissolved in the respective volumes of 
water to product 0.1% or 0.2% formulation concentrations. Then, four 
pieces of 41/2 inch by 6 inch dacron (65%)-cotton (35%) clothes (referred 
to herinafter as D/C VCD) soiled with a particulate/oily soil are added 
and the cloth is washed for 10 minutes at a paddle oscillation rate of 90 
cycles per minute. The cloth is then squeezed by hand and rinsed for 1 
minute in fresh water (same volume and hardness as initially used; rinse 
temperature is 100.degree. F. for runs in which 120.degree. F. washing is 
used and 80.degree. F. for runs in which 80.degree. F. washing is used). 
The cloth is again squeezed by hand to remove excess water and dried in a 
commerical clothes dryer. The reflectance of the cloth is measured by a 
Gardner Color Difference Meter Model XL10. The detergency of the 
formulation is expressed as %Detergency and is calculated from the 
following expression: 
##EQU1## 
The following examples serve to demonstrate the invention herein.