Note: Descriptions are shown in the official language in which they were submitted.
~ ~ 7'~g~6
Aqueous crutcher mixes containing substantial
proportions of bicarbonate, carbonate and silicate tend to
gel or set prematurely, sometimes before they can be thoroughly
mixed and pumped out of a crutcher to spray towers. Consequent-
ly, extensive experimentation has been undertaken to find waysto diminish the tendencies of such systems to solidify or gel
in the crutcher. Small quantities of citric acid or water
soluble citrate incorporated in ~he crutcher mix delay or
prevent gelation and setting of bicarbonate - carbonate -
lo silicate mixes and allow commercial spray drying thereof,following normal procedures for pumping ou~ the crutcher
contents to the spray nozzles. However, while the use of
citric acid or citrate was successful, it has been supplanted
by tlle present process, which represents a significant improve-
ment over it. In addition to improving the anti-gelling activity
and increasing the length of time in which a crutcher mix will be
workable without the need for significantly larger proportions
of anti-gelling agent being incorporated, 'che present invention
allows the use of a lesser proportion of organic material, there-
by decreasing the liklihood of the spray dried composition deter-
iorating in the heat of the dryer and improving the absorbency
and flowability of the product. Also, whereas the citric acid
component, if used in larger quantity, might interfere with
the absorption of liquid nonionic detergent sprayed onto the
sprny dried l~ase beads, magnesium sulfate appears to be
dcsirably absor~cnt, thereby helping to make the product
rrCc flowin~.
~ ~ 7094G
In tllo aqueous cL-utcher mix tlle various dissolved
compounds can ionize and therefore it may be considered that
in the crutcher mix there are ~resent magnesium, citrate and
sulfate ions. ~ccordingly, crutcher mixes having charged
thereto mixtures of compounds that result in the same ionic
composition are also useful for retarding and preventing
gelations of inorganic crutcher mixes. Thus, magnesium
citrate or magnesium acid citrate could be employed, preferably
with sodium sulfate, but also without the sulfate being present.
Citric acid and the various water-soluble citrates may be referred
to herein as "citric material".
In accordance with the present invention, a miscible
and pumpable crutcher slurry which does not prematurely set
~ refer~b/y
and whi~h is capable of being mixed and pumped~for a period of at
least one or two hours after making, comprises from 40 to 70%
of solids and 60 to 30% of water, of which solids content, on
a 100% solids basis, about 55 to 85% is sodium bicarbonate,
about 5 to 25% is sodium carbonate and about 5 to 25% is
sodium silicate of Na20:SiO2ratio within the range of 1:1.4
to 1 3s with the ratio of sodium bicarbonate : sodium carbonate
being within the range of about 2:1 to 8:1, the ratio of
sodium carbonate : sodium silicate being within the range of
about 1:3 to 3:1, and the ratio of sodium bicarbonate : sodium
silicate being within the range of about 3:1 to 10:1, and a
gelation retarding proportion of a combination of 0.1 to 2%
of a citric material selected from the group consistin~ of
citric acid, water soluble citrate and mixtures thereof, and
from 0.1 to 1.4% oE magnesium sulfa~e, wlth the total oi such
-- 3 --
~ ~ 7i~
citric material and magnesium sulfate, in combination, being
gelation retarding and at least 0.4~ of the slurry. The inven-
tion also relates to a method for retarding or preventing the
gela~ion of a miscible and pumpable crutcher slurry of the
general bicarbonate - carbonate - silicate type described, by
addition thereto of a citric material and magnesium sulfate, in
the described small quantities. The invention is also of simi-
lar products and methods wherein magnesium citrate is present as
an anti-gelling material.
Although the anti-gelling features oE the present
invention may also be obtained with other inorganic buildex base
compositions than those which are primarily of bicarbonate,
carbonate, silicate and water, the most significant anti-gelling
effects are noted when crutcher mixes based substantially
(preferably essentially) on such materials and water are treated
by the method of this invention, i.e., addition of citric
material and magnesium sulfate (or magnesium citrate). The
compositions so treated comprise about 40 to about 70% of solids
and are about 60 to about 30% of water. The solids contents, on
a 100% solids basis, are about 55 to about 85% of sodium bicar-
bonate, about 5 to about 25% of sodium carbonate and about 5 to
about 25% of sodium silicate, of Na20:SiO2 ratio within the
range of 1:1.4 to 1:3. In such compositions the ratio of sodium
bicarbonate : sodium carbonate is within the range of about 2:1
to about 8:1, the ratio of sodium carbonate : sodium silicate is
--4--
) ,1
within the range of about 1:3 to about 3:1, and the ratio of
sodium bicarbonate : sodium silicate is within the range of
about 2:1 to about 10:1. The proportion of citric material,
which is citric acid, water soluble citrate, mixture of such
citrates or mixture of citric acid and such citrate(s), will be
from about 0.1 to about 2% and the percentage of magnesium sul-
fate will be from 0.1 to 1.4%. The total of citric material and
magnesium sulfate will be at least 0.4% and will usually not
exceed 2.5 or 3%, with the percentages mentioned being on a
total crutcher mix or slurry basis, including the mentioned
salts, water and any adjuvants which may be present. A
preferred range of such total is 0.5 to 3%, more preferably 0.6
to 2% and most preferably, usually, 0.7 to 1.2%. Although the
employment of a combination of citric material, such as citric
acid, and magnesium sulfate is preferable, there may be used in
substitution for it from 0.3 to 3% of magnesium acid citrate
(MgHC6HsO7-5H2~) or equivalent proportion ofequivalent
magnesium citrate.
Preferably, the crutcher slurry contains from 50 to
65% of solids, with the balance being water, and of the solids
content, 55 to 80% is sodium bicarbonate, 10 to 25% is sodium
carbonate and 10 to 25% is sodium silicate, with the ratio of
sodium bicarbonate : sodium carbonate being in the range of 3:1
to 6:1, the ratio of sodium carbonate : sodium silicate being
within the range of 2:5 to 5:2 and the
1 1 7~6
ratio of sodium bicarbonate : sodium silicate being within
~he range of q:l ~o 8:1. More pre~erably, the crutcher
slurry contains from 5g to 64% of solids and 42 to 36% of
water, of which solids content 70 to 75% is sodium bicarbonaté,
13 to 19~ is sodium carbonate and 8 to 15'~ is sodium silicatc.
In such more preferred compositions the ratio of sodium
bicarbonate : sodium carbonate is within the range of 4:1 to
5:1, the ratio of sodium carbonate : sodium silicate is
within the range of 1:1 to 3:2 and the ratio of sodium
bicarbonate : sodium silicate is within the range of S:l to
7:1. The materials described herein, except for water, are
all normally solid and the percentages and ratios are on an
anhydrous basis, although the various materials may be added
to the crutcher as hydrates r OL dissolved or dispersed in
water. Normally, however, the sodium bicarbonate is anhydrous
and the sodium carbonate is soda ash. ~'et, the carbonate
monohydrate may also be employed. The silicate is usually
added to the crutcher slurry as an aqueous solution, normally
of 40 to 50~ soli~s co~l~ent, e.g., 47.5%, and is preferably
added near the end of the mix~ng process and after previous
addings and dispersings and~dissolvings of the citric material
and magnesium sulfate (or magnesium citrate). The silicate
employed ~lill preferably be of Na20:SiO2 ratio within the
range of 1:1.6 to 1:2.6, more preferably 1:1.6 to 1:2.4 and
most preferably 1:2.0 to 1:2.4.
9 ~ ~
Although it is highly preferred to make the crutcher
slurry and the base bead product of this invention (from which a
heavy duty built nonionic synthetic organic detergent composi-
tion can be produced) of essentially inorganic salts, in such
manner that they will be of bead properties that promote absorp-
tion through the bead surfaces of nonionic detergent sprayed
thereon in liquid form, and although often the adjuvants, such
as perfumes, colorants, enzymes, bleaches and flow promoting
agents, may be sprayed onto the beads with the nonionic deter-
gent or may be post-added, or stable and normally solid adju-
vants, mixing in with the inorganic salt slurry in the crutcher
may be feasible. Thus, it is contemplated that from 0 to 2S
much as 20% of the crutcher slurry may be of suitable adjuvants
or diluents (diluents including inorganic salts, such as sodium
sulfate and sodium chloride). However, if such adjuvants are
present, normally the proportion thereof will be from 0.1 to 10%
and often their content will be limited to 5%, and sometimes to
1 or 2%. Normally the organic material content of the crutcher
slurry will be limited to about 5% maximum, preferably 3~
maximum and most preferably 1 or 1.5% maximum, so as to avoid
any problems of tackiness of the base beads after spray drying
and to avoid any adverse effects on absorption of synthetic
nonionic organic detergent by the beads.
'~
I 1 7~9~6
The preferred combination cJelation prevcnting
S materials employed, which have been found to be startlingly
successful in preventing gelation, thickening, setting and
freezing up of the crutcher slurry before it can be emptied
from the crutcher alld spray dried, using nonnal crutching,
pumping and spray drying equipment, are citric material and
magnesium sulfate. Because the crutcher slurry, includin~
both dissolved and dispersed inorganic salts, is normally
alkaline, usually bcing of a p~l in the range of 9 to 12,
preferably 10 to 11, when the citric material employed is
citric acid it is considered ~o be ionized and convcrted to
the corresponding citrate or brought into equilibrium with
citrate ions. Thus, other soluble citrates may be employed
instead of citric acid, including sodium citrate, potassium
citrate and mac~nesium citrate, although for many applications
the acid is consiaered to be superior. Instead of adding
citrate, a mixture of the acid and a neutralizinc3 agent,
e.g., NaOH, I~O~I Mg(O~l)2, may be used, and instead of the
acid form, a eitrate plus an acid ean be substituted, if
desired (although this latter course of action will rarely
be followed). The proportion of citric material, in combination
with magnesium sulfate will normally be only sufficient to
accomplish the gelation preventing task in the particular
~ 3 70~46
crutcher slurry to be treated. However, for safety ' 5 sake an
excess, e.g., S to 20~ more than the sufficient quantities of
citric material and magnesium sulfate, may be employed. While
it is possible to use as much as 3.4~ of the combination of
citric material and magnesium sulfate, on a crutcher contents
weight basis, to retard or prevent gelation, usually from 0.4 to
1.5~ will suffice, preferably from 0.5 to 1.2%. When employing
a citrate, such as an alkali metal citrate, one may wish to
increase the percentage of the additive slightly to compensate
for the presence of the heavier cation but for simplicity's sake
the range of proportions of additives given will apply to both
the acid and salt forms. With respect to the magnesium com-
pound, the sulfate is highly preferred but this may be replaced
by other sources of magnesium as by the magnesium ion in mag-
nesium citrate, when that compound is used, preferably in
proportion from 0.4 to 1.2% or 0.5 to 0.8%.
The order of addition of the various components to the
crutcher is not considered to be critical, except that it is
highly desirable to add the silicate solution last, and if not
last, at least after the addition of the gel preventive combina-
tion of materials. Also, minor variations in orders of addition
may be made under certain circumstances, as when objectionable
foaming accompanies the following of a specific order. However,
such problems have not been found to be serious. In some
instances it is possible to
_9_
~, ~
~1709~
premix the ma~nesium sulfate and citric material and to add the
mixture thereof to the crutcher. In other cases the citric
material is added first, followed by the magnesium sulfate,
or vice versa. If desired, one or both of the citric material
and magnesium sulfate may be premixed with another n.~terial
or with other materials. In such instances it will be
preferred for thc anti-gelling additivc componcnts to be
mixed in with other crutcher mix matcrials before addition
of the silicate to the crutcher. Ilowever, in some instances
one can add thc anti-gelling materials after addition of the
silicate, but preerably very promptly thereafter.
Usually, during the manufacture of the crutcher
mix some water will be added to the crutcher initially,
followed by some inorganic sal~, either carbonate or bicarbonate,
more water and more salt, and then, gel preven'Live materials
and silicate, but dispersion-solutions of the individual
componcnts may be made beforehand, if ~easible. The water
employed may be city water of ordinary hardness; In theory,
it is preferable to utilize deionized water or distilled
water, if available, because some metallic impurities in the
water may havc a triggering ~ction on gcl formation, but
that is not considered to be necessary.
The temperature of the aqueous medium in the
crutcher will usually be elevated, normally to the 40 to
70C. range and preferably will be from 50 ~o 60C. Heating
- 10 -
t 1 709~6
the crutcher medium promotes solution of the water svluble
salts of the mix and thereby increascs mix mobility. Ilowever,
temperatures higher than 70C. will usually be avoided
because of the possibility of decomposition of one or more
crutcher mix components, e.g., sodium bicarbonatc. ~eating
of the crutcher mix, which may be effected by utilizing hot
aqueous medium charged and by heating the crutcher contents
by means of a heating jacket or heating coils, also helps
to increase drying tower throughput because less energy has
to be transferred to the sprayed droplets of crutcher mix in
the tower. Using higher solids mixes al~o increases production.
Crutcher mixing times to obtain good slurries can
vary widely, from as little as ten minutes for small crutchers
and for slurries of higher moisture contents, to as m ch as
four hours, in some cases. The mixing times needed to bring
all the crutchcr mix components together in one medium may
be as little as five minutes but in some cases, can take up
to an hour, although 30 minutes is a preferable upper limit.
Counting any such init;al admixing times, normal crutching
periods will be from 20 minutes to two hours, e.g., 30
minutes to one hour, but th~ crutcher mix will be such as to
be mobile, not gclled or set, for at least one hour, prefer-
ably for two hours and more preferably for four hours or
so after completion of the making of the mix, e.g., 10 to 30 hrs.
The crutched slurry, with the various salts,
dissolved or in particulate form,uniformly distributed
~ 1 709~6
therein, in part due to the desirable anti-gelling effects of
the citric compound and the magnesium sulfate, is transferred in
usual manner to a spray drying tower, which is located near the
crutcher. The slurry is normally dropped from the bottom of the
crutcher to a positive displacemen-t pump, which forces it at
high pressure through spray nozzles at the top of a conventional
spray tower (countercurrent or concurrent), wherein the droplets
of the slurry fall through a hot drying gas, which is usually
composed of fuel oil or natural gas combustion products, in
which the droplets are dried to desired absorptive bead form.
During the drying, part of the bicarbonate is converted to
carbonate, with the release of carbon dioxide, which appears to
improve the physical characteristics of the beads made so that
they become more absorptive of liquids, such as liquid nonionic
detergent, which may be post sprayed onto them subsequently.
After drying, the product is screened to desired size,
e~g., 10 to 100 mesh, United States Standard Sieve Series, and
is ready for application of nonionic detergent spray thereto,
with the beads being either in warm or cooled (to room tempera-
ture) condition. However, the nonionic detergent will usuallybe at an elevated temperature to assure that it will be liquid;
yet, upon cooling to room temperature, desirably it will be a
solid, often resembling a waxy solid. The nonionic detergent,
applied to the tumbling beads in known manner, as a spray or as
droplets, is preferably a condensation product of ethylene
-12-
~ ~ 7~)34~
oxide and higher fatty alcohol, with the higher fat-ty alcohol
being of 10 to 20 carbon atoms, preferably of 12 to 16 carbon
atoms, and more preferably averaging 12 to 13 carbon atoms, and
with the nonionic detergent containing from 3 to 20 ethylene
oxide groups per mole, preferably from 5 to 12, more preferably
6 to 8. The proportion of nonionic detergent in the final
product will usually be from 10 to 25~, such as from 20 to 25%.
Whereas when using citric acid alone as the anti-gelling agent,
without the magnesium sulfate, the absorbency of the base beads
would be good, with some base bead compositions and nonionic
detergents it would be difficult to have more than 20% of the
nonionic detergents satisfactorily absorbed by the base beads.
It has been found that the present anti-gelling treatment,
utilizing a mixture of citric material and magnesium sulfate,
e.g., citric acid and magnesium sulfate, can result in beads of
significantly greater absorbency, allowing absorption of 22% of
nonionic detergent, with the production of a free flowing
product and sometimes allowing absorption of as much as 25~ of
the nonionic detergent. In comparative tests against beads made
using citric compound alone (citric acid) as the anti-gelling
agent in the base bead crutcher mix, compositions of the present
invention, made by the methods thereof, are more absorptive, as
a general rule.
A preferred finished formulation made from base
t 1 7~946
bcads o~ this invcntion cont~ins from l5 to 25~, prefcrably
20 to 25% of the nonionic uetergent, ~.C3., Neodol 23-6.5,
made by Shell Chemical Company, 30 to 40% of sodium bicarbonate,
20 to 30~ of sodium carbonate, 5 to 15% of sodium silicate
of Na2O:SiO2 ratio of 1:2.4, 1 to 3~ of fluoresce~t brighterel,
0.5 to 2% of proteolytic enzyme, sufficient bluiny to coloi-
the product and whiten the wash, as dcsircd, 0.5 to 3% of
moisture, 0.5 to 1.2% of citric material, preferably sodium
citrate and 0.~ to 2% of magnesium sulfate. Instead of the
mixture of citric material and magnesiur,l sulfate there may
be present from 0.3 to 3% of magnesium citrate, preferably 0.4
to 1~2%. Optionally, sodium sulfate may be present, as a
diluent, but the amounts thereof will normally b~ restricted
to 20~ preferably to 10% antl most prcferably to less than
5~, if it is prcsent at all. The base bcads made, devoid of
nonionic detergent and adjuvants, will preferably comprise
from 35 or 40 to 60% of sodium bicarbonate, 15, 20 or 25 to 45%
of sodium carbonatc, 10 to 20% of sodiwn silicate, 0.1 to 3~
of sodium citrate ~u.l to 2~ of magnesium sulfate (or 0.5 to
5~ of magnesium citrate), 0 tq 10~ of adjuvant(s~ and/or
c.iluent(s) and 1 to 10~ of moisture. In such products the
prcportion of sodium bicarbonate in the sprayed beads will
normally be within the r~nge of 1.2 to 4 times that of
sodium carbonate, e.g., 1.5 to 3 times.
The highly beneficial result: of incorporating the
mcntioned small percentages of citric compound and magnesium
sulfate or magnesium citrate in the crutcher slurry in
- 14 -
I :~ 7~9~
accordance with this invention is two-fold, gelation and setting
of the crutcher mix in the vessel before complete discharge
thereof is preven-ted and additionally, higher solids content
crutcher slurries may be made. Thus, down times and cleanouts
are eliminated and enexgy savings are achieved due to less water
having to be evaporated from the crutcher droplets in the spray
dryer. Although many bicarbona~e - carbonate - silicate mix-
tures desirably employed in crutcher mixes for making base beads
for built particulate nonionic detergent compositions would
normally gel and set up in the crutcher, with the present inven-
tion, at little expense and without any detrimental effects on
the product, the desired proportions of such builder salts can
be employed and variations in such proportions can be made, as
desired, without fear of freeze-ups of the crutcher. Tests of
the final product show no adverse effects due to the presence of
the citric material and magnesium sulfate therein. In fact,
some positive results, due to metal ion sequestration and
improved absorption of nonionic detergent, may result. The
presence of the citric material is thought to promote mainten-
ance of the stability of perfumes and colors present and it mayhelp to prevent development of malodors from deteriorations of
other organic additives, such as proteolytic enzymes and
proteinaceous materials. The presence of the citric materials
and the magnesium sulfate in the base beads also has the desi-
rable effect of having the gelation preventing material present
-15-
'
i~7~ 3~
in any base beads or detergent beads being reworked, so that
such material, if off-specification (as for being undersize or
for being tower wall buildup), may be mixed wlth water and made
into a more concentrated rework mix for subsequent blending back
with the regular crutcher mix. Such mixing with water is easier
than would be the case were the anti-gelling composition not
present in the base beads to prevent or retard gelation or
excessive thickening.
The following examples illustrate but do not limit the
invention. Unless otherwise indicated all temperatures are in
C, and all parts are by weight in the examples and throughout
the specification.
EXAMPLE 1
Final Product Component Percent
~onionic Detergent (~eodol 23-6.5)18.6
Proteolytic enzyme 1.4
Moisture 1.5
NaHC03 46.0
Na2C3 19 . O
Sodium silicate (Na20:SiO2 = 1:2.4) 10.9
Sodium citrate 0.9
Magnesium sulfate (as Epsom salt)0.8
Adjuvants (fluorescent brightener, bluing,
perfume) o.g
1 00 . O
-16-
I ~ 70~6
A product of the above formula is made by spray drying
a crutcher mix comprising sodium bicarbonate, sodium carbonate,
sodium silicate, citric acid, magnesium sulfate, fluorescent
brightener and water in a spray tower to produce essentially
inorganic base beads, after which there is sprayed onto the
surfaces of such beads a nonionic detergent in liquid state,
solidifiable at room temperature, the beads and detergent are
cooled and proteolytic enzyme powder and perfume are applied to
them. The product made, of the formula given, is of a bulk
density of 0.8 g./ml. and an initial adhesion of 40~ and exhi-
bits a fines characteristic (through United States Standard
Sieve No. 50) of 15~.
The base beads are made by adding to the crutcher 308
parts of water, 15 parts of fluorescent brightener, 1.5 parts of
blue pigment, 4.5 parts of anhydrous citric acid, 10 parts of
magnesium sulfate (Epsom salt3, 403 parts of sodium bicarbonate
(anhydrous), 87.5 parts of soda ash, and 170 parts of a 47.5
solids content aqueous sodium silicate solution, the sodium
silicate of which is of Na20:SiO2 ratio of 1:2.4. During the
mixing of this base builder composition the temperature in the
crutcher is maintained at about 38C. It takes about 20 minutes
for the various materials to be mixed together in the order
given (except that the brightener, pigment and citric acid are
added in two parts, with the second halves being added after the
soda ash), and after completion of addition of the last compo-
nent the mixing is continued for about another 20 minutes, after
which spray drying of the product is begun. Some of the
crutcher mix is not sent to the spray dryer so that the time for
-17-
~370g~1~
gelation thereof may be measured. It is found that the crutcher
mix remains miscible and pumpable, ungelled and uncongealed for
30 hours. 'rhe crutcher mix, which is pumped to the spray tower,
using a Triplex positive displacement pump generating a pressure
of about 30 kg./sq. cm., is dried in drying air, which is the
combustion products of an oil burner, at a temperature ranging
from a high of 400 to 600C. to a low of about 100 to 200C. and
drying is to a moisture content of about 1.9%. The base beads
resulting are screened so as to be within the 10 to 100 mesh
United States Sieve Series range and are free flowing, non-tacky
and of a bulk density of about 0.7 g./ml. They are porous, yet
firm on the surfaces thereof and are capable of readily absorb-
ing significant proportions of liquid nonionic detergent without
becoming objectionably tacky. The detergent products made,
including absorbed nonionic detergent, are excellent heavy duty
laundry detergents, useful in washing household laundry in
automatic washing machines and in cleaning textile materials by
other methods, too.
In variations of this experiment, using the same
proportions of all components except for water, citric acid and
magnesium sulfate, when the amounts of such components are
changed to 322, 3.5 and 10, respectively, the gelation time at
37.8~C. is found to be ten hours; when changed to 313, 4.5 and
5, respectively, it is eight hours; when changed to 307, 4.5 and
11.3, respectively, it is 7.5 hours; when changed to 314, 3.5
-18-
~ ~ 709 1~
and 5, respectively, it is five hours; and when changed to 311,
2.5 and 10, respectively, it is four hours. Such crutcher mix
compositions are of excellent stability and are very useful in
commercial production of the present detergent base beads
because they allow extra time before gelation, so that any
"normal" problems associated with crutching and spray drying may
usually be overcome before gelation or setting up in the
crutcher could become a problem. When the mentioned proportions
are 30.9, 2.5 and 11.3 or 317, 4.5 and 1, respectively, the
crutching time, at 37.8C., before gelation will be 3.5 hours
and when the proportions are 316, 1.5 and 5 it will be 1.5
hours. Such formulations are also acceptable, especially the
first two, because usually the contents of the crutcher can be
completely sprayed out within 1.5 hours and almost always within
3.5 hours. However, it will usually be desirable to utilize
more citric acid or magnesium sulfate or equivalent materials
than the 1.5 and 5 parts mentioned, just to provide extra time
against untoward incidents.
When the proportions of citric acid and/or magnesium
sulfate and/or the sum thereof are outside the ranges given in
the specification, premature gelation occurs or a satisfactory
dispersion is not made. For example, when 30.2 parts of water,
2.5 parts of citric acid and 19 parts of magnesium sulfate are
employed the product gels immediately, which also occurs when
304 parts of water, 0.5 part of citric acid and 19 parts of
--19--
; ~r
~~
~ ~ 70g46
magnesium sulfate are utilized, or when such proportions are
304, 3.5 and 15 or 306, 1.5 and 15. Gelation occurs within
about 25 minutes when the proportions are 321, 0.5 and 1 and
within about 20 minutes when they are 313, 0.5 and 10. Thus, it
can be seen that the compositions of the present invention, made
by the described methods, are especially useful in the prepara-
tion of spray dried base builder beads for heavy duty laundry
detergents, without the danger of premature gelation of the
crutcher mix.
When sodium citrate is substituted for citric acid in
the formulas given above, with the magnesium sulfate being
either anhydrous or in Epsom salt, similar results are obtained.
Also, w~en equivalent proportions of magnesium citrate are em-
ployed, whether Mg2(citrate)3 or MgHC6HsO7-5H2 ~ e-g-~ 1-5%
good anti-gelling effects are obtained, although they are not as
good as those for the combination of citric acid (or sodium
citrate) and magnesium sulfate.
The crutcher mixes of this invention may be of greater
solids contents than those for similar compositions in which a
sufficient quantity of citric acid is employed (without the
magnesium sulfate) to obtain the same (or somewhat inferior)
anti-gelling effects. Thus, the presence of the magnesium sul-
fate with the citric acid appears to improve the anti-gelling
effects so that even higher contents of solids may be present in
the crutcher slurries without gelation. In the past it has been
found that solids content and gelation tendencies were directly
proportional and this is also the case when combinations of
-20-
g~
citric acid and magnesium sulfate are employed. Still, one can
utilize higher solids content crutcher mixes without objection-
able gelling, whereas similar mixes, when trea-ted with citric
acid alone, could gel prematurely. Also, when the citric acid -
magnesium sulfate mixture is employed the content of organic
material in the product may be minimized, while still maintain-
ing the crutcher slurry miscible for sufficiently long periods
of time to avoid crutcher set-ups or line blockages.
EXAMPLE 2
In comparative experiments a crutcher mix formulation
is made essentially like that of the crutcher mix which results
in a base bead for making a detergent composition of the formula
first given in Example 1, but with the solids content of the
crutcher mix being kept at 56.5%. The mix is made in the same
manner and the crutching times up to objectionable gelation are
measured when various materials are added with the citric acid
as anti-gelling agents, in replacement of the magnesium sulfate.
Using 0.25% of citric acid and 1~ of each of such other anti-
gelling "salt" additives, on an anhydrous basis, the slurry
fluidity is maintained for only about 20 minutes when either
sodium chloride or calcium chloride is the salt employed, which
is about the same time for which fluidity is maintained when the
citric acid is used alone. Wi-th sodium sulfate as the
-21-
~ ~ 7t~9L16
salt added the slurry life is extended to l.S hours and
calcium sulfate allows mixing for u~ ~o five hours. Magnesium
silicate results in an initially thin slurry, which solidifies
in about five hours. Calcium oxide and magnesium oxide'make'
very highly VisCollS slurries which solidify in a few hours.
Magnesium chloride extends the slurry life to ten hours and
magnesiti:l sulfate extends it to more than 32 hcurs. However,
when various hea~ sta~le adjuvants are present ill the crutcher
mix, such as bluing, fluorescent brightener and other normal
detergent adjuvants for crutcher mixos,it has becn found that
gelation is accelorated, sometimes occurring in one-tenth
to one-half the -time normally taken. Thus, since it is
desirable that at least an hour be provided before gelation
and preferably, that more time should be available, none of
tl~e anti-gelling salts exccpt the magnesium chloride and
magnesium sulfate is considered to be useful and of these
two the magnesium sulfate is clearly superior. On the basis
of above experiments it is within the invention to utilize
magnesium chloric'e with citric acid or to employ a mixture
of magnesium chloride and magnesium sulfate with citric acid.
EX~M~LE 3
The experiment of Example 2 is repeated but the order
of addition of the detergent builder salt components to the
crutcher is altered so that the bicarbonate, carbonate and
silicate are mixed together in the aqueous'medium before
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1 3 7g)g'1 S
addition thereto oE the magnesium sulfate and citric acid. In
such case, after a few minutes the mix becomes objectionably
thick and solidifies in an irreversible manner. However, if as
it is noted tha-t the mix is thickening, the magnesium sulfate
component or the magnesium sulfate-citric acid anti-gelling
composition is quickly added at that time, before solidifica-
tion, it will thin the mix to a workable state. This is another
advantage of the present invention because, in addition to
extending the crutching time, it allows control of the fluidity
of the crutcher mix in response to indications of gelation, as
they appear. Thus, the crutcher operator has improved process-
ing control during the period in which the mix is held in the
crutcher before spray drying. Should there be some interruption
of spray tower operation, necessitating holding the mix longer
in the crutcher than planned, he can extend the period of misci-
bility of the crutcher mix by further addition of magnesium
sulfate and citric acid or equivalent anti-gelling agent(s) of
this invention or magnesium sulfate alone, in many instances.
For example, it has been found that often as little as 0.3% of
MgSO4 or 0.6% of Epsom salt will reverse gelation, providing
that the mix is still fluid enough to permit mixing in of the
magnesium salts. Normally, from 0.3 to 1% of MgSO4 will be
added. This feature of the invention allows minimizing of the
magnesium sulfate and citric acid contents of the product, so
that product characteristics will not be changed noticeably, and
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yet assures the operator that he will not have to dig solidified
crutcher mix out of the crutcher, with the waste of material and
loss of production time that would be involved. This improve-
ment in the manufacturing process is important because if the
crutcher mix solidifies, spray tower operation can be halted,
essentially shutting down the detergent manufacturing operation.
When operations are restarted even when that is done reasonably
promptly after gelling first occurs, the spray tower will have
to be brought to equilibrium, and during the first part of such
resumed manufacturing some unacceptable product can result.
Sometimes gelation in the crutcher is not so extensive as to
solidify the mass of mix but still the production of some gel
can block spray nozzles and cause interruption of production.
Such adverse effects are avoided by use of the present process,
as herein described.
EXAMPLE 4
An attempt is made to make a crutcher mix of the type
described in Example 2, utilizing 0.25~ of citric acid and 1~ of
magnesium sulfate (anhydrous), with the order of addition of the
various components being changed so that the water, silicate,
magnesium sulfate and citric acid are first mixed together,
after which the bicarbonate and carbonate are added, plus the
fluorescent dye and pigment. However, such crutcher mixes gel
prematurely and for that reason the mentioned order of addition
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is unsatisfactory. The experiment was repeated several times
but in all cases the crutcher mix froze so that it could not be
stirred, pumped or spray dried.
EXAMPLE 5
Attempts were made to manufacture in laboratory equip-
ment crutcher mixes containing high solids contents. Thus using
the basic formulas previously given, with 0.25% of citric acid
and 1% of magnesium sulfate, and adding the components in the
operative order described in Examples 1 and 2, the builder salt
composition was 70% of sodium bicarbonate, 20% of soda ash and
10% of sodium silicate in one instance, 77%, 13% and 10% in the
second and 67%, 23% and 10% in the third, so that the bicarbon-
ate:carbonate ratios were 3.5:1, 6:1 and 3:1, respectively.
Such products could not be made in laboratory equipment but are
makable, especially with additional magnesium sulfate and citric
acid, up to twice as much as being employed initially, when
heavy duty plant equipment is utilized.
In a similar manner three other formulations were
made, lower in solids content, comprising 56%, 19% and 25% in
the one case, 60%, 15% and 25% in the second case and 60%, 20%
and 20% in the third case, of sodium bicarbonate, soda ash and
sodium silicate, so that the bicarbonate:carbonate ratios are
3:1, 4:1 and 3:1, respectively. Such products are very easily
manufactured, even in laboratory equipment, but because of the
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~ 1 7Q~'1 6
need to evaporate more water during the spray drying process
they are not as economically feasible as higher solids content
crutcher mixes. In the described experiments the silicate is
that of Example 1.
From the above experiments it is seen that the present
invention is an important one. The anti-gelling materials being
employed allow the use of higher solids content crutcher mixes
and thereby conserve energy (less drying air needed) and
increase throughputs The invention also ensures that crutcher
mix :Ereeze-ups do not occur, with the loss of time and materials
that would otherwise result. Operations at higher crutcher
temperatures are permissible despite the fact that increasing
such temperatures would otherwise increase the probability of
gelation of the crutcher mix. The magnesium salt anti-gelling
agents improve product characteristics to a significant extent
and although one will usually attempt to minimize the citric
acid or other citric material content, the presences of such
materials have good effects, too. It appears from the experi-
mental results that the solids content of the crutcher mix may
be as high as 70~ in some circumstances and good mixing and
sufficiently delayed gelation are obtainable by means of the
present invention, despite such high solids contents. Also, the
crutcher mix temperature may go as high as 70C. Of course, at
such higher solids contents and temperatures stronger mixing
would usually be used and often more anti-gelling agent will be
present.
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