Technical Field
[0001] The present invention relates to granular detergent compositions containing a specific
mixture of alkylbenzene sulfonate surfactant, alkyl sulfate surfactant, alkali metal
silicate and water-soluble sulfate. The compositions are prepared by drying, preferably
by spray-drying, an aqueous slurry comprising the above components. While the compositions
preferably also contain detergent builder materials, there should be relatively little
or no pyrosphosphate or anhydrous Form 1 tripolyphosphate builder in that portion
of the composition prepared by drying the slurry comprising the sulfonate and sulfate
surfactants, silicate and sulfate.
[0002] Mixtures of alkylbenzene sulfonate and alkyl sulfate surfactants are desired for
optimum detergency performance. However, such mixtures tend to gel on contact with
water. This can result in poor solubility of granules having high levels of alkylbenzene
sulfonate and alkyl sulfate surfactants, particularly when such granules are incorporated
in dense detergent compositions.
[0003] It has now been found that very soluble granular detergent compositions containing
high levels of alkylbenzene sulfonate and alkyl sulfate surfactants can be obtained
by drying an aqueous slurry comprising the surfactants, silicate in a weight ratio
of surfactant to silicate within the range of from 1.5:1 to 6:1, sulfate and relatively
little or no pyrophosphate or anhydrous Form 1 tripolyphosphate detergent builder
material. In preferred compositions, these soluble detergent granules are admixed
or agglomerated with builders and other optional detergent ingredients. Particularly
preferred compositions are obtained by admixing the soluble granules with builders,
compacting the admix at relatively low pressures (e.g., 137.9 kPa to 1379 kPa and
optionally admixing additional builders and other ingredients to provide finished
granular detergent compositions.
Background Art
[0004] U.S. Patent 4,028,283, Murata et al, issued June 7, 1977, discloses granular detergents
containing surfactants having a tendency to cake and an anticaking agent formed by
reacting polyethylene glycol with an acid anhydride. The compositions can also contain
0-20% of other surfactants such as alkylbenzene sulfonates. Spray-dried detergents
containing mixtures of alkylbenzene sulfonate and alkyl ethoxy sulfate surfactants,
silicate and builders are exemplified.
[0005] U.S. Patent 4,141,841, McDanald, issued February 27, 1979, discloses granular detergents
containing particulate and antistatic/softening additives. In Example 8, the particles
are mixed with spray-dried base granule containing about 27% of a mixture of alkylbenzene
sulfonate and alkyl ethoxy sulfate surfactants, 18% silicate and about 22% sodium
tripolyphosphate.
[0006] Japanese OPI 106509, published August 21, 1979, discloses spray-dried granular detergents
containing 15-40% surfactant, 5-20% silicate and no more than 12% phosphate. The compositions
are said to have good physical properties and to cause less deposition of insolubles
on clothes.
[0007] Japanese OPI 72998 and 72999, published April 25, 1985, disclose dense granular detergents
formed by high shear mixing of alkylbenzene sulfuric acid and alkyl sulfuric acid
with sodium carbonate and water to cause neutralization, admixing other ingredients
such as builders, and then crushing and granulating the mixture.
Summary of the Invention
[0008] This invention relates to a granular detergent composition prepared by:
(1) forming base granules comprising, by weight:
(a) from 30% to % of a mixture of a C₁₁-C₁₃ alkylbenzene sulfonate surfactant and
a C₁₂-C₁₆ alkyl sulfate surfactant in a weight ratio of sulfonate surfactant to sulfate
surfactant of from 4:1 to 1:4;
(b) an alkali metal silicate having a molar ratio of SiO₂ to alkali metal oxide of
from 1.0 to 3.2;
the weight ratio of (a) to (b) being from 1.5:1 to 6:1;
(c) from 15% to 60% of a water-soluble sulfate; and
(d) from 0% to 20% of a pyrophosphate or anhydrous Form 1 tripolyphosphate detergent
builder material or mixtures thereof; said composition prepared by drying an aqueous
slurry comprising the above components.
Detailed Description of the Invention
[0009] The granular detergent compositions of the present invention contain from 30% to
85%, preferably from 35% to 60 %, more preferably from 40% to 50%, by weight of a
mixture of C₁₁-C₁₃ alkylbenzene sulfonate surfactant and C₁₂-C₁₆ alkyl sulfate surfactant
in a weight ratio of sulfonate surfactant to sulfate surfactant of from 4:1 to 1:4,
preferably from 3:1 to 1:3, more preferably from 2:1 to 1:2.
[0010] Sulfonate surfactants useful herein are the watersoluble salts, particularly the
alkali metal, ammonium and alkanolammonium (e.g., monoethanolammonium or triethanolammonium)
salts of alkylbenzene sulfonates in which the alkyl group contains from 11 to 13 carbon
atoms, in straight chain or branched chain configuration, e.g., those of the type
described in U.S. Patents 2,220,099 and 2,477,383.
[0011] Preferred are linear straight chain alkylbenzene sulfonates in which the average
number of carbon atoms in the alkyl group is from 12 to 13.
[0012] Useful alkyl sulfate surfactants are the water-soluble salts, particularly the alkali
metal, ammonium and alkanolammonium (e.g., monoethanolammonium or triethanolammonium)
salts of C₁₂-C₁₆ linear or branched alkyl sulfates. Preferred are those containing
a C₁₂-C₁₅, especially C₁₄-C₁₅, linear alkyl group.
[0013] The compositions herein can also contain minor amounts (generally less than about
30%, but preferably less than about 15%, by weight of the above sulfonate and sulfate
surfactants) of other detergent surfactants known in the art. These can include anionic,
nonionic, cationic, ampholytic and zwitterionic surfactants, such as those disclosed
in U.S. Patent 3,919,678, Laughlin, et al, issued December 30, 1975.
[0014] The compositions of the present invention also contain an alkali metal silicate having
a molar ratio of SiO₂ to alkali metal oxide of from 1.0 to 3.2, preferably from 1.6
to 2.4. Sodium silicate, particularly having a molar ratio of from 1.6 to 2.2, is
preferred.
[0015] The alkali metal silicates can be purchased in either liquid or granular form. Silicate
solutions or slurries can conveniently be used to avoid having to dissolve the dried
form in the aqueous slurry (e.g., crutcher mix) of the components herein.
[0016] In addition, the weight ratio of the alkylbenzene sulfonate plus alkyl sulfate surfactants
herein to the alkali metal silicate should be from 1.5:1 to 6:1, preferably from 2:1
to 4:1, more preferably from 2:5:1 to 3.5:1.
[0017] The present compositions further contain from 10% to 60%, preferably from 20% to
50%, by weight of a water-soluble (preferably sodium) sulfate. Sodium sulfate is usually
formed during the sulfation/sulfonation and neutralization steps in the production
of the alkylbenzene sulfonate and alkyl sulfate surfactants herein.
[0018] The compositions herein prepared by drying an aqueous slurry comprising the components.
The slurry generally contains from 25% to 70%, preferably from 40% to 60%, water,
whereas the dried granules initially contain from 1% to 10%, preferably from 1% to
3%, water. The drying operation can be accomplished by any convenient means, such
as by using spray-drying towers, both counter-current and co-current, fluid beds,
flash-drying equipment, or industrial microwave or oven-drying equipment. These are
more fully described in U.S. Patent 4,019,998, Benson et al, issued April 26, 1977
(particularly from Column 14, line 19 to Column 15, line 9).
[0019] The granular detergents herein are very soluble in the wash water even though they
contain high levels of alkylbenzene sulfonate and alkyl sulfate surfactants. Good
solubility is obtained when the weight ratio of total sulfonate plus sulfate surfactant
to silicate is within the 1.5:1 to 6:1 range specified above. While not intending
to be limited by theory, it is believed that this relatively high level of silicate
provides structure and helps to maintain integrity of the high surfactant granules
and that this minimizes gelling when the surfactants contact the wash water. However,
if the silicate level becomes too high (e.g., a surfactant to silicate ratio of 1:1),
overall solubility can suffer due to the formation of silicate insolubles. On the
other hand, granules having a surfactant to silicate ratio of, for example, 8:1, have
insufficient structure and tend to be too mushy at these high surfactant levels.
[0020] For good solubility, the amount of detergent pyrophosphate or anhydrous Form 1 tripolyphosphate
builder material in the portion of the granular detergent obtained by drying an aqueous
slurry of the essential components herein should also be minimized. Thus the compositions
can contain from 0% to 20%, preferably from 0% to 15%, more preferably from 0% to
material in the portion of the granular detergent obtained by drying an aqueous slurry
of the essential components herein should also be minimized. Thus the compositions
can contain from 0% to 20%, preferably from 0% to 15%, more preferably from 0% to
10%, by weight of such detergent builder material or mixtures thereof. Most preferably,
the compositions are substantially free of such detergent builder (e.g., they contain
less than 5%, preferably less than 3%, by weight of such builder).
[0021] The compositions can contain up to 60% preferably from 1% to 45% by weight of other
detergent builders including any of those described in U.S. Patent 3,925,262, Laughlin
et al, issued December 9, 1975. Builders are generally selected from the various water-soluble
alkali metal, ammonium or substituted ammonium phosphates, polyphosphates, phosphonates,
polyphosphonates, carbonates, borates, polyhydroxy sulfonates, polyacetates, carboxylates,
and polycarboxylates. Preferred are the alkali metal, especially sodium, salts of
the above.
[0022] Specific examples of inorganic phosphate builders are sodium and potassium tripolyphosphate,
(Form 11 or hydrated Form 1), polymeric metaphosphate having a degree of polymerization
of from about 6 to 21, and orthophosphate. Examples of polyphosphonate builders are
the sodium and potassium salts of ethylene diphosphonic acid, the sodium and potassium
salts of ethane 1-hydroxy-1,1-diphosphonic acid and the sodium and potassium salts
of ethane, 1,1,2-triphosphonic acid. Other phosphorus builder compounds are disclosed
in U.S. Patents 3,159,581; 3,213,030; 3,422,021; 3,422,137; 3,400,176; and 3,400,148.
[0023] Examples of nonphosphorus, inorganic builders are sodium and potassium carbonate,
bicarbonate, sesquicarbonate, and tetraborate decahydrate.
[0024] Water-soluble, nonphosphorus organic builders useful herein include the various alkali
metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates
and polyhydroxy sulfonates. Examples of polyacetate and polycarboxylate builders are
the sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylene
diamine tetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, mellitic acid,
benzene polycarboxylic acids, and citric acid.
[0025] Polymeric polycarboxylate builders are also described in U.S. Patent 3,308, 067,
Diehl, issued March 7, 1967. Such materials include the water-soluble salts of homo-
and copolymers of aliphatic carboxylic acids such as maleic acid, itaconic acid, mesaconic
acid, fumaric acid, aconitic acid, citraconic acid and methylenemalonic acid.
[0026] Other useful builders herein are sodium and potassium carboxymethyloxymalonate, carboxymethyloxysuccinate,
cis-cyclohexanehexacarboxylate, cis-cyclopentanetetracarboxylate, phloroglucinol
trisulfonate, and the copolymers of maleic anhydride with vinyl methyl ether or ethylene.
[0027] Other suitable polycarboxylates are the polyacetal carboxylates described in U.S.
Patent 4,144,226, issued March 13, 1979 to Crutchfield et al, and U.S. Patent 4,246,495,
issued March 27, 1979 to Crutchfield et al.
[0028] These polyacetal carboxylates can be prepared by bringing together under polymerization
conditions an ester of glyoxylic acid and a polymerization initiator. The resulting
polyacetal carboxylate ester is then attached to chemically stable end groups to stabilize
the polyacetal carboxylate against rapid depolymerization in alkaline solution and
converted to the corresponding salt.
[0029] A preferred phosphate builder is Form 11 sodium tripolyphosphate preferably anhydrous.
A preferred builder for use in compositions that are substantially free of phosphate
builders is sodium citrate.
[0030] When admixed, the builders herein should have the same particle size as the remainder
of the composition, as described hereinafter.
[0031] The above granular detergent compositions can be used as is as finished detergent
compositions or as detergent additive compositions. However, they are preferably used
as (and hereinafter referred to as) detergent base granules which are then admixed
or agglomerated with builder material and with other optional ingredients to provide
finished detergent compositions exhibiting good solubility. Such finished compositions
can comprise by weight from 5% to 50%, preferably from 10% to 40%, more preferably
from 12% to 25%, of the alkylbenzene sulfonate and alkyl sulfate surfactants herein
and from 5% to 95%, preferably from 10% to 85%, more preferably from 15% to 75%, of
detergent builder material, such as described above. However, for best solubility,
the amount of pyrophosphate and anhydrous Form 1 tripolyphosphate should be minimised
i.e. the finished compositions preferably contain from 0% to 20% preferably from 0%
to 10% of such material or mixtures thereof.
[0032] The compositions can also contain minor amounts, generally less than 30%, preferably
less than 20%, by weight of other ingredients usually included in detergent compositions.
These include auxiliary detergent surfactants, color speckles, bleaching agents, and
bleach activators, suds boosters or suds suppressors, antitarnish and anticorrosion
agents, soil suspending agents, soil release agents, dyes, fillers, optical brighteners,
germicides, pH adjusting agents, nonbuilder alkalinity sources, enzymes, enzyme-stabilizing
agents and perfumes.
[0033] Agglomeration can be accomplished by agitating in the presence of a suitable binder
(e.g., in a fluidized bed, tumble mixer, or a rotating drum or pan) or by mechanically
mixing under pressure (e.g., extruding, pressing, milling, compacting or pelletizing).
Final sizing can then be achieved by grinding and screening.
[0034] In a preferred embodiment, the detergent base granules are admixed with from 0% to
300%, preferably from 25% to 200%, more preferably from 50% to 150%, by weight of
the base granules, of a detergent builder material such as described above. The resulting
admix is then preferably compacted at a relatively low pressure of from 137.9 to 1379
preferably from 275.8 to 1034 more preferably from 344.8 to 689.4 kilo Pascals (kPa).
[0035] The composition is then preferably admixed with an additional 0% to 300%, preferably
from 25% to 200%, more preferably from 50% to 150%, by weight of the base granules,
of a detergent builder material. The above levels and types of builder material and
compaction pressure are preferably selected so that the final detergent composition
has a bulk density of from 0.55 to 1.2, preferably from 0.65 to 1.1, more preferably
from 0.70 to 0.9 g/cc and an average particle size of from 20 to 1500 microns, preferably
from 50 to 1200 microns, more preferably from 100 to 800 microns.
[0036] The above compaction step is preferably accomplished by using equipment that applies
a relatively uniform compaction pressure, for example, by using compaction rollers
with smooth (i.e., noncorrugated) surfaces. After compaction, the composition is preferably
granulated and screened to provide an average particle size similar to that desired
for the final composition.
[0037] The following nonlimiting examples illustrate the detergent compositions of the present
invention.
[0038] All percentages, parts and ratios are by weight unless otherwise specified.
Example I
[0040] The following granular detergent composition was prepared.
[0041] The base granules were produced by spray-drying an aqueous crutcher mix of the components
on a 305 cm tower using a crutcher temperature of 93°C a size 3-1/2 nozzle to make
fine granules, and silicone deaeratants. If the base granules contained more than
2% moisture, a second drying stage on a continuous fluid bed was performed to reduce
moisture to 2%.
[0042] The base granules were then admixed with powdered STP hexahydrate to form the preblend.
The preblend was compacted at 344.8 kPa roll pressure on a 10 cm by 25 cm chilsonator,
and screened to select a -14(1168 microns)/+65(208 microns) particle size cut (Tyler
mesh). Oversized particles were collected and granulated on a Fitzmill using a 1168
microns screen and low rpm's. This was screened to select a -20(833 microns)/+ 48(295
microns) particle size cut. Both materials were dedusted by blowing off fines in a
fluid bed dryer using ambient air.
[0043] The admix was prepared at 181.5 kg per batch in a drum mixer. Carbonate, granular
STP (with dye sprayed-on), brightener, enzymes, and suds suppressor prills were blended
with the compacted mainstream product cut and regranulated overs. The ratio of mainstream
product cut to overs was 7 to 1. Mineral oil was sprayed on the final admix in 13.6
to 18.1 kg batches at a 1% level using a Forberg Mixer.
[0044] The composition of Example 1 is preferably incorporated into a laminated laundry
product formed from two plies of water insoluble tissues, at least one of which is
water permeable, which are laminated together. At least one of the plies has cup like
depressions, surrounded by rims and the other ply being attached to the first ply
at the rims to physically separate the cups. In one embodiment the laminate is made
with plies of the tissue paper described by Trokhan in U.S. Patent 4,529,480, issued
July 16, 1985.
[0045] The tissue had good air permeability as set forth in U.S. Patent 4,170,565, Flesher
et al, issued October 9, 1979.
[0046] There are 12 cups, having 20 cc capacity each and at least 8 of the cups are filled
with about 9 gm (11 cc) of the detergent composition and the other cups are filled
with at least one detergent adjuvant. Other materials which can be used to form suitable
laminates and processes for forming suitable laminates are disclosed in Bahrani US
Patent No. 4571924 and European Patent Application Publication No. 0184261.
[0047] When the composition of Example 1 is incorporated in said laminated laundry product,
it exhibits superior solubility.
Example II
[0048] The following granular detergent composition can be prepared and used according to
Example I.