Field of the Invention
[0001] This invention relates to a process for making a granular detergent product and the
product of the process. More particularly, the invention relates to a process for
preparing detergent compositions which are useful in automatic dishwashing machines.
State of the Art
[0002] Detergent compositions comprising in combination an alkali metal polyphosphate such
as sodium tripolyphosphate, alkaline salts such as sodium silicate and sodium carbonate,
a surfactant and a chlorine containing compound that provides hypochlorite ion in
solution have particular utility for machine dishwashing. The production of such compositions
made of agglomerates of the ingredients has generally been accomplished by the addition
of water or an aqueous sodium silicate solution to a mixture of dry ingredients. Compositions
prepared in such manner, however, are characterized by a tendency to cake in their
cartons during storage and can also have a tendency to cake in the dispenser cups
of automatic dishwashing machines. A number of process modifications have been suggested
to reduce the caking tendency of detergent compositions prepared using water or silicate
solutions as agglomerating agents. U.S. Patent 2,895,916 discloses an order of addition
in which chlorinated trisodium phosphate is added to the composition only after the
aqueous silicate has been added to an anhydrous polyphosphate. A carton caking benefit
is said-to result from a more rapid hydration of the sodium tripolyphosphate in the
absence of chlorinated trisodium phosphate.
[0003] It has now been found that a substantial reduction in the dispenser cup caking tendency
of agglomerated detergent compositions containing sodium tripolyphosphate, an alkali
metal silicate and a low-foaming nonionic surfactant can be achieved if from 2% to
[0004] 20% of certain alkali metal salts are added to the detergent composition after the
agglomeration step comprising the addition of water or an aqueous alkali metal silicate
solution to a particulate mixture comprising sodium tripolyphosphate has commenced
and preferably is substantially complete.
[0005] It is an object of this invention to produce agglomerated granular detergent compositions
which are resistant to caking in dispenser cups.
[0006] Other objects and advantages will be apparent from the following description and
examples.
Summary of the Invention
[0007] According to the present invention there is provided a process for preparing agglomerated
granular detergent composition comprising from 15% to 50% of sodium tripolyphosphate,
from 5% to 25% silicate solids wherein the average SiO
2:M
2O weight ratio is from 1.0 to 3.6, M being an alkali metal, from 2% to 12% of a low-foaming
nonionic surfactant and from 2% to 20% of alkali metal chlorides and mixtures thereof,
wherein the said agglomerated granular detergent composition is prepared by agitating
particulate components comprising anhydrous sodium tripolyphosphate, contacting said
particulate components during said agitation with an agglomerating agent comprising
water, mixing said agglomerating agent with said particulate components by continuing
said agitation, adding a dispenser cup caking inhibitor during said agitation after
at least 30% of said agglomerating agent has been added to said particulate components,
said dispenser cup caking inhibitor comprising said one or more alkali metal chlorides
and being a dry material having a particle size such that at least 80% passes through
a screen of mesh size 0.422 mm, and recovering said agglomerated granular detergent
composition. The invention also embraces a composition prepared in accordance with
the above process.
Detailed Description of the Invention
[0008] The process of the invention is carried out in apparatus suitable. for the mixing
of dry particulate components and adapted so that liquid components such as water
or an aqueous alkali metal silicate solution agglomerating agent can be sprayed on
or otherwise added to a bed or falling curtain of one or more particulate components
during the mixing operation. Any suitable mixing device such as an inclined pan aggldmerator,
a rotating drum or any other vessel with suitable means of agitation may be used.
Methods of agitating, mixing and agglomerating particulate components are well known
to those skilled in the art. The apparatus may be designed or adapted for either continuous
or batch operation so long as the essential process steps can be achieved.
[0009] Optional process steps include screening of particulate materials before processing,
screening or grinding the composition to any desired particle size, addition of optional
ingredients such as an alkali metal dichlorocyanurate bleach and sodium carbonate,
and allowing the final composition to come to equilibrium with respect to temperature
and hydration before packing into cartons.
[0010] The theoretical basis for the unexpected improvement in dispenser cup caking resistance
provided by incorporation of the dispenser cup caking inhibitor is believed to be
at least partially related to the complex hydration characteristics of anhydrous sodium
tripolyphosphate. This compound has different hydration characteristics depending
on its method of manufacture. A so-called Form I is produced if the process of manufacture
includes a relatively high temperature calcination step. A Form II results when lower
temperatures are employed. Form I is characterized by relatively rapid hydration characteristics.
Form II, particularly in the absence of any substantial level of Form I material,
is slow to hydrate, but has a greater immediate solubility. Commercially available
sodium tripolyphosphate is generally a mixture of Form I and Form II. U.S. Patents
2,622,068, 2,961,409 and 2,961,410, disclose the hydration characteristics of Form
I and Form II sodium tripolyphosphate in the manufacture of spray-dried detergents.
[0011] The process and product of this invention apply to granular detergent compositions
comprising the following essential ingredients: (1) sodium tripolyphosphate; (2) alkali
metal silicate; (3) a low-foaming nonionic surfactant; and (4) an alkali metal salt
dispenser cup caking inhibitor.
Sodium Tripolyphosphate
[0012] The detergent compositions of the invention contain sodium tripolyphosphate at a
level of from 15% to 50% and preferably from 25% to 45% by weight.
[0013] Anhydrous sodium tripolyphosphate comprises. all or a part of the particulate components
contacted with the agglomerating agent in the process aspect. of the invention. The
sodium tripolyphosphate can be in granular form such that at least 90% is retained
on a 100 Tyler mesh screen or in powdered form such that at least 90% passes through
a 100 Tyler mesh sereen.
[0014] Optional polyphosphates useful in the practice of the invention are the water-soluble
sodium and potassium salts of pyrophosphoric acid (H
4P
2O
7) and polymeric metaphosphoric acid (HP0
3)n. The value of n is typically below - 50 in the interest of water solubility. The
sodium and potassium salts of metaphosphoric acid are often designated "glassy" phosphates
and exist as a series of polymers. Glassy phosphates may also be represented by the
formula (M
20)m(P
20
5)n wherein M is an alkali metal, n is in the range of from 5 to 50 and m:n is in the
range of 1:1 to 1:1.5 on a molar basis. An example of a glassy phosphate is sodium
hexametaphosphate (Na
6P
6O
18).
The Alkali Metal Silicate
[0015] The compositions made by the process of this invention contain alkali metal silicate
solids at a level of from 5% to 25% on an anhydrous weight basis and having an average
Si0
2:M
20 weight ratio of from 1.0 to - 3.6, M being an alkali metal. Particularly preferred
is a sodium silicate having a weight ratio of Si0
2:Na
20 of from 1.6 to 3.3, most preferably from
[0016] 2 to 3.2. Lower ratio silicates which are relatively more alkaline provide good cleaning
performance but in order to provide protection to materials such as aluminum and china,
it is desirable to have at least 10% and up to 75% of the Si0
2 present at a SiO
2:Na
2O ratio above 3.0. It is possible to add all of the silicate in the form of aqueous
solutions typically containing from 35% to 55% silicate solids but all or a portion
may be part of the particulate components comprising sodium tripolyphosphate or added
in dry form at some other point in the process. Aqueous alkali metal silicate solutions
used as agglomerating agents preferably contain at least 45% water.
[0017] Silicate solids in the compositions of the invention can be added dry in anhydrous
or hydrous form. Preferably at least a' portion of the total silicate is hydrous silicate
mixed with sodium tripolyphosphate before the addition of an agglomeration agent.
Low-Foaminq Nonionic Surfactant
[0018] The compositions of this invention contain from 2.0% to 12% of a low-foaming nonionic
surfactant by weight. A preferred level of surfactant is from 3.0% to 8.0%. Preferably
the surfactant is an alkoxylated nonionic surfactant and preferably the composition
is essentially free of sulfonated or sulfated anionic surfactants.
[0019] Examples of nonionic surfactants include:
(1) the condensation product of 1 mole of a saturated or unsaturated, straight or
branched chain, alcohol or fatty acid containing from 10 to 20 carbon atoms with from
4 to 50 moles of ethylene oxide. Specific examples of such compounds include a condensation
product of 1 mole of coconut fatty acid or tallow fatty acid with 10 moles of ethylene
oxide; the condensation of 1 mole of oleic. acid with 9 moles of ethylene oxide; the
condensation product of 1 mole of stearic acid with 25 moles of ethylene oxide; the
condensation product of 1 mole of tallow fatty alcohols with about 9 moles of ethylene
oxide; the condensation product of 1 mole of oleyl alcohol with 10 moles of ethylene
oxide; the condensation product of 1 mole of C19 alcohol and 8 moles of ethylene oxide; and the condensation product of one mole of
C18 alcohol and 9 moles of ethylene. oxide. The condensation product of a fatty alcohol
containing from 17 to 19 carbon atoms, and being substantially free of chain lengths
above and below these numbers, with from 6 to 15 moles, preferably 7 to 12 moles,
most preferably 8 moles, of ethylene oxide is particularly preferred. This can be
capped with a low molecular weight (C1-5) acid or alcohol moiety, so as to minimize or eliminate the need for a suds-suppressing
agent.
(2) Polyethylene glycols having molecular weights of from 1,400 to 30,000, e.g., 20,000; 9,500; 7,500; 6,000; 4,500; 3,400; and 1,450. All of these materials are waxlike solids which
melt between '49°C and 93°C.
(3) The condensation products of 1 mole of alkyl phenol wherein the alkyl chain contains
from 8 to 18 carbon atoms and from 4 to 50 moles of ethylene oxide. Specific examples
of these nonionics are the condensation products of 1 mole of decylphenol with 40
moles of ethylene oxide; the condensation product of 1 mole of dodecylphenol with
35 moles of ethylene oxide; the condensation product of 1 mole of tetradecylphenol
with 25 moles of ethylene oxide; the condensation product of 1 mole of heptadecylphenol
with 30 moles of ethylene oxide, etc.
(4) Polyoxypropylene, polyoxyethylene condensates having the formula.

where y equals at least 15 and (C2H4O)x+x equals 20% to 90% of the total weight of the compound and the molecular weight
is from 2,000 to 10,000, preferably from 3,000 to 6,000. These materials are, for
example, the PLURONICS which are well known in the art.
(5) The compounds of (1) which are capped- with propylene oxide, butylene oxide and/or
short chain alcohols and/or short chain fatty acids, e.g., those containing from 1
to 5 carbon atoms, and mixtures thereof.
(6) Condensation products of ethylene oxide and propylene oxide with a low molecular
weight trifunctional alcohol such as glycerine or trimethylolpropane. These materials
are, for example, the PLURADOT polygols made by the BASF Wyandotte Corporation.
[0020] Preferred surfactants are those having the formula RO-(C
2H
4O)
xR
1 wherein R is an alkyl or alkylene group containing from 17 to 19 carbon atoms, x
is a number from 6 to
[0021] 15, preferably from 7 to 12, and R is selected from hydrogen, C
l-5 alkyl groups, C
2-5 acyl groups and groups having the formula -(C
yH
2yO)
nH wherein y is 3 to 4 and n is a number from 1 to 4.
[0022] Also preferred are the low sudsing compounds of (4), the other compounds of (5),
and C
17-19 materials of (1) which have a narrow ethoxy distribution.
[0023] In addition to the above mentioned surfactants, other suitable surfactants can be
found in the disclosure of U.S. Patents 3,544,473, 3,630,923, 3,888,781 and 4,001,132.
Alkali Metal Salt Dispenser Cup Caking Inhibitor
[0024] The compositions of the invention contain from 2% to 20%, preferably from 4% to 15%,
of a dispenser cup caking inhibitor selected from alkali metal chlorides and mixtures
thereof.
[0025] Operative dispenser cup caking inhibitors are in the form of dry powders having a
particle size such that at least 80% passes through a 35 Tyler mesh screen (mesh size
0.422 mm). The dispenser cup caking inhibitor is added during the process of the invention
after at least 30%, preferably 75%, and most preferably 90%, of the water or aqueous
sodium silicate agglomerating agent has been added to the particulate components comprising
sodium tripolyphosphate.
[0026] An especially preferred material is sodium chloride having a particle size such that
at least 80% passes through a 100 Tyler mesh screen (mesh size 0.152 mm).
Water
[0027] The compositions of the invention are made by a process in which either water or
an aqueous sodium silicate solution is used as the agglomerating agent.
[0028] The finished compositions will contain water in the form of hydrated salts, preferably
from 9% to 12% by weight.
Alkali Metal Dichlorocyanurate
[0029] Sodium or potassium dichlorocyanurate is optionally but preferably incorporated in
the compositions of the invention in an amount sufficient to provide available chlorine
equal to from 0.75% to 2.5% by weight of the composition. A preferred material is
sodium dichlorocyanurate dihydrate as disclosed in U.S. Patent 3,936,386, which provides
56% available chlorine by weight. The ability of a compound to provide hypochlorite
ion in solution is generally measured as "available chlorine". The available chlorine
reflects the method of producing an inorganic hypochlorite (e.g., 2 NaOH + Cl
2→ - NaOCl + NaCl + H20).. Available chlorine is the chlorine liberated by acidification
of a solution of hypochlorite ions and at least a molar equivalent amount of chloride
ions. The usual analytical method of determining available chlorine in a solution
is addition of an excess of an iodide salt and titration of the liberated free iodine
with a reducing agent.
Optional Alkali Metal Carbonates
[0030] Optionally, the process and composition of the invention utilize alkali metal carbonate
to provide the alkalinity needed for optimum cleaning performance.
[0031] Alkali metal carbonates, particularly sodium carbonate, can be present in the compositions
at levels up to 25%, preferably from 2% to - 12% by weight.
Other Optional Ingredients
[0032] In addition to the above ingredients it can be desirable, if the product sudses too
much, to incorporate one of the many suds-suppressing ingredients disclosed in the
above mentioned patents at a level of from 0.01% to 10%, preferably from 0.05% to
3%. The preferred suds suppressing materials are mono- and distearyl acid phosphates;
the self-emulsified siloxane suds suppressors of U.S. Patent 4,126,045, and mixtures
thereof.
[0033] Organic sequestering builders such as citrates and nitrilotriacetates can be present
in the compositions, but preferably at levels no greater than 10% by weight. The presence.of
organic builders tends to hurt the performance of these compositions by leaving visible
spots and filming on glassware.
[0034] China protecting agents including aluminosilicates, aluminates, etc., can be present
in amounts up to 5%, preferably from 0.2% to 2%.
[0035] Filler materials, sodium sulfate in particular, to control product density and other
physical characteristics can also be present in amounts up to 60%, preferably not
more than 30% by weight.
[0036] Dyes, perfumes, crystal modifiers and the like can also be added in minor amounts.
[0037] As used herein, all percentages, parts and ratios are by weight unless otherwise
stated.
[0038] The following Examples illustrate the invention and facilitate its understanding.
EXAMPLE I
[0039] A. 33.1 Parts by weight of powdered anhydrous sodium tripolyphosphate and 8.0 parts
by weight of hydrous sodium silicate (82% solids, Si0
2:Na
20 weight ratio of 2.4) were added to a ribbon mixer. With the mixer in operation the
following ingredients were added during a cycle time of 180 seconds.
a) from 0 seconds to 165 seconds--added as a spray blend of 13.8 parts of an aqueous
sodium silicate solution containing 47.3% silicate solids with a SiO2:Na2O weight ratio of 2.0 and 4.7 parts of an aqueous sodium silicate solution containing
37.5%. silicate solids with a Si02:Na20 weight ratio of 3.2. This solution also con- .tained minor amounts of perfume and
dye.
. b) at 60 seconds--added dry 19.4 parts of sodium sulfate and 10.0 parts of sodium
carbonate.
c) from 60 seconds to 165 seconds--added as a spray 4.0 parts of a polyoxyalkylene
nonionic surfactant (condensation product of C18 alcohol with average of 8.25 moles ethylene oxide).
d) at 145 seconds--added dry 5.0 parts of sodium chloride having a particle size such
that at least 80% passed through a 100 Tyler mesh screen (mesh size 0.152 mm).
e) after 180 seconds
Product is discharged from mixer.
f) 2.5 parts of sodium dichlorocyanurate dihydrate was added and mixed in after drying
and aging of the product discharged from the mixer at step e).
B. The process of A was repeated with the elimination of step d). 24.4 Parts sodium
sulfate .added at step b) replaced the sodium chloride of step d).
[0040] The compositions were packed in airtight containers pending evaluation. Resistance
to automatic dishwasher dispenser cup caking was measured as indicated in the table
below.

[0041] Composition A was superior to Composition B in resistance to dispenser cup caking.
No Composition A remained in the dispenser cup at the end of the rinse cycle, the
point of principal notice of dispenser cup caking.
EXAMPLE II
[0042] The process of Example I-A was repeated with the substitution of NaCl having a particle
size such that 80% passed through a 35 Tyler mesh screen (mesh size 0.422 mm) and
less than 20% passed through a 100 Tyler mesh screen (mesh size 0.152 mm). The resultant
composition was superior to Composition B of Example I but slightly inferior to Composition
A of Example I.
EXAMPLE III
[0043] The materials listed in the table below were added to Composition B of Example I
at the levels and process cycle time indicated. 300 grams of each resultant composition
was mixed with 100 grams of 37°C distilled water and stirred in a 400 ml beaker. Viscosity
of the product slurries was measured by a Brookfield spindle viscometer (No.4 spindle/6
rpm) after seven minutes.
[0044] The reduction in viscosity for each additive was found to be predictive of the improvement
in resistance to dispenser cup caking.

[0045] All dispenser cup caking inhibitor materials listed above had a particle size such
that at least 80% by weight passed through a 100 Tyler mesh screen (mesh size 0.152
mm) except granular NaCl for which 80% passes through a 35 Tyler mesh screen (mesh
size 0.422 mm) and 50% is retained on a 65 Tyler mesh screen (mesh size 0.211 mm).
1. A process for preparing agglomerated granular detergent composition comprising
from 15% to 50% of sodium tripolyphosphate, from 5% to 25% silicate solids wherein
the average Sio2:M2o weight ratio is from 1.0 to 3.6, M being an alkali metal, from 2% to 12% of a low-foaming
nonionic surfactant and from 2% to 20% of alkali metal chlorides and mixtures thereof,
characterised in that the said agglomerated granular detergent composition is prepared
by agitating particulate components comprising anhydrous sodium tripolyphosphate,
contacting said particulate components during said agitation with an agglomerating
agent comprising water, mixing said agglomerating agent with said particulate components
by continuing said agitation, adding a dispenser cup caking inhibitor during said
agitation after at least 30% of said agglomerating agent has been added to said particulate
components, said dispenser cup caking inhibitor comprising said one or more alkali
metal chlorides and being a dry material having a particle size such that at least
80% passes through a screen of mesh size 0.422 mm, and recovering said agglomerated
granular detergent composition.
2. A process according to Claim 1 wherein the dispenser cup caking inhibitor is sodium
chloride.
3. A process according to either one of Claims 1 and 2 wherein the dispenser cup caking
inhibitor has a particle size such that at least 80% passes through a screen of mesh
size 0.152 mm.
4. A process according to any one of Claims 1-3 wherein the dispenser cup caking inhibitor
is added after at least 75% of said agglomerating agent has been added to said particulate
components.
5. A process according to any one of Claims 1-4 which additionally comprises an alkali
metal dichlorocyanurate to provide an available chlorine level of from 0.5% to 3.0%.
6. A process according to any one of Claims 1-5 wherein the low-foaming nonionic surfactant
comprises a condensation product of an alcohol or a fatty acid containing from 10
to 20 carbon atoms with from 4 to 50 moles ethylene oxide.
7. A process according to any one of Claims 1-5 wherein the low-foaming nonionic surfactant
comprises a compound having the formula RO-(CH2H4O)xR1 wherein R is an alkyl or alkylene group containing from 17 to 19 carbon atoms, x
is a number from 6 to 15 and R1 is selected from hydrogen, C1-5 alkyl groups, C2-5 acyl groups, and groups having the formula -(CyH2yO)nH wherein y is 3 to 4 and n is from 1 to 4.
8. An agglomerated granular detergent composition when prepared according to the process
of any one of Claims 1-7.