Spray drying of a detergent containing a porus crystal-growth-modified carbonate

Granular spray-dried detergent compositions including a liquid component unsuitable for spray-drying are prepared by co-spray-drying a slurry of a porous crystal-growth-modified carbonate-based carrier salt and a detergent slurry containing detergent-active compounds, builders and other suitable ingredients, and then treating the resulting composite powder with the liquid component. The porous carrier salt is preferably the sodium carbonate/sodium sulphate double salt Burkeite, crystal-growth-modified by means of a polymeric polycarboxylate.

TECHNICAL FIELD OF INVENTION 
The present invention relates to a process for the preparation of granular 
detergent compositions containing a porous crystal-growth-modified 
carbonate salt, as described and claimed in EP No. 221 776A (Unilever), as 
a carrier for liquid detergent components. 
BACKGROUND AND INTRODUCTION 
EP No. 221 776A (Unilever), published on May 13, 1987, describes and claims 
novel porous materials suitable for carrying liquid components in 
detergent compositions. One such material, crystal-growth-modified 
Burkeite, is prepared by drying (preferably spray-drying) a slurry 
containing sodium carbonate and sodium sulphate in an appropriate ratio 
and a crystal growth modifier, added to the slurry not later than the 
sodium carbonate so as to influence the growth of crystals of the double 
salt Burkeite. Crystal-growth-modified Burkeite is characterised by a high 
capacity for taking up liquid detergent components and one possible way in 
which it may be used in detergent compositions is as a base or carrier for 
nonionic surfactant in an "adjunct" which is postdosed to a spray-dried 
base powder. The adjunct is prepared by spraying liquid or liquefied 
nonionic surfactant onto the modified Burkeite carrier material, and is 
then postdosed to a spray-dried base powder containing anionic surfactant, 
possibly nonionic surfactant, phosphate and/or non-phosphate builder, 
sodium silicate, fluorescer and other non-heat-sensitive ingredients: this 
procedure is especially beneficial as a method for incorporating in 
powders those nonionic surfactants that are unsuitable for spray-drying 
because of unacceptable tower emission ("pluming" or "blue smoke"). The 
adjunct may, for example, contain from 5 to 40% by weight of nonionic 
surfactant, and may itself constitute, for example, from 5 to 20% by 
weight of the final detergent powder. 
Phosphate-built and zero-phosphate powders containing such adjuncts are 
described in the aforementioned European specification in Examples 24 and 
25: in comparison with similar powders where the nonionic surfactant was 
incorporated via the slurry, both powders exhibited substantially improved 
physical properties. To prepare these powders, however, two separate 
spray-drying operations--of the Burkeite carrier, and of the base 
powder--are necessary. This can cause difficulties in factories having 
only one spray-drying tower, and may necessitate storage of the Burkeite 
carrier material on site for prolonged periods and/or transport of this 
material between different factory sites. 
It has now been discovered that powders of comparable properties can be 
prepared in a single spray-drying tower by spraying in separate slurries 
of powder and crystal-growth-modified Burkeite to form a composite 
product, and subsequently spraying liquid nonionic surfactant onto the 
composite product. The process can be used also for other porous 
carbonate-based carrier salts and other liquid detergent components. 
PRIOR ART 
Processes in which two different slurries are sprayed into a spray-drying 
tower are known in the art. EP No. 139 539A (Unilever) discloses a process 
in which a first slurry containing heat-stable components is spray-dried 
in a conventional manner from a position near the top of the tower, while 
a second slurry containing heat-sensitive components, such as soap or 
nonionic surfactant, is sprayed in at a lower level. U.S. Pat. No. 
4,129,511 (Ogoshi et al/Lion) describes a process for preparing detergent 
powders containing aluminosilicate builders, in which process a detergent 
slurry and an aluminosilicate slurry are subjected simultaneously to 
spray-drying within the same drying space. Our copending European patent 
application No. 87 308239.0 filed on Sept. 17, 1987 describes and claims a 
process in which a detergent slurry and an aqueous solution of alkali 
metal silicate are sprayed simultaneously into a spray-drying tower so as 
to form composite granules. 
DEFINITION OF THE INVENTION 
The present invention provides a process for the preparation of a granular 
detergent composition, which comprises the steps of: 
(i) preparing a first aqueous slurry comprising sodium carbonate, 
optionally together with sodium sulphate and/or sodium bicarbonate, and an 
effective amount of a crystal growth modifier which is an organic material 
having at least three carboxyl groups in the molecular, the crystal growth 
modifier being incorporated in the slurry not later than the sodium 
carbonate; 
(ii) simultaneously spray-drying the first aqueous slurry and a second 
aqueous slurry comprising one or more anionic and/or nonionic surfactants, 
one or more detergency builders and optionally one or more further 
heat-insensitive detergent components, to form a powder including a 
crystal-growth-modified carbonate-based carrier salt; 
(iii) treating the powder obtained from step (ii) with a liquid detergent 
component. 
For convenience, the first slurry will be referred to hereinafter as the 
carbonate slurry, and the second slurry as the base powder slurry. 
DESCRIPTION OF THE INVENTION 
The present invention is directed to a preferred method for preparing 
detergent powders which contain a liquid detergent component adsorbed on a 
porous carbonate-based crystal-growth-modified carrier salt, as described 
and claimed in the aforementioned EP No. 221 776A (Unilever). 
Three different porous carbonate-based crystal-growth-modified salts are of 
especial interest: sodium carbonate itself, mainly in monohydrate form but 
containing some anhydrous material; sodium sesquicarbonate, which is a 
hydrated carbonate/bicarbonate double salt of the formula 
EQU Na.sub.2 CO.sub.3.NaHCO.sub.3.2H.sub.2 O; 
and Burkeite, an anhydrous carbonate/sulphate double salt of the formula 
EQU 2Na.sub.2 SO.sub.4.Na.sub.2 CO.sub.3. 
All three salts exhibit crystal growth modification, when prepared by 
drying a slurry containing the appropriate salt(s) and a crystal growth 
modifier added to the slurry not later than the sodium carbonate. The 
crystal growth modified materials are characterised by small needle-like 
crystals interspersed with very small pores, and are very useful as 
carriers of liquid detergent components. 
The sodium carbonate/sodium sulphate double salt Burkeite represents an 
especially preferred embodiment of the invention. This material forms 
small crystals (about 10 .mu.m) but in the normal block-like crystal form 
these are packed together in dense aggregates and the material has a low 
absorptivity for liquids. As explained in the aforementioned EP No. 221 
776A (Unilever), Burkeite can be converted to a more desirable 
needle-shaped crystal form in the slurry by the addition of a low level of 
a polycarboxylate material at a particular stage in the slurry-making 
process. Crystal-growth-modified spray-dried Burkeite contains small 
needle-shaped crystals similar to those of sodium tripolyphosphate 
hexahydrate, and can be shown by mercury porosimetry to be interspersed to 
a large extent with very small (&lt;3.5 .mu.m) pores. These powders are 
capable of absorbing and retaining substantial quantities of liquid 
nonionic surfactants and other organic detergent components as a direct 
result both of a change in crystal form and of a less dense form of 
crystal packing, giving particles of greater porosity than those produced 
in the absence of a crystal growth modifier. The modified crystal 
structure can be recognised by optical or electron microscopy. 
Instead of preparing a separate adjunct by treating the 
crystal-growth-modified carrier salt with nonionic surfactant or other 
liquid detergent component and then postdosing that adjunct to a 
spray-dried base powder, in accordance with the invention the two slurries 
are simultaneously sprayed into a spray-drying tower to prepare a 
composite material containing both crystal-growth-modified carrier salt 
and base powder, and that composite material is then treated with the 
liquid detergent component. 
Although the simultaneous drying of two slurries in the same tower is known 
per se, as indicated above under "Prior Art", this procedure would not 
have been expected to be effective in the context of the present invention 
because of the low absorptivity of base powder for liquid detergent 
components, especially nonionic surfactant. Typically a spray-dried base 
power containing anionic surfactant, sodium tripolyphosphate builder and 
minor ingredients will not take up more than about 2% by weight of 
nonionic surfactant, while a porous carbonate-based carrier salt will take 
up 20% by weight or more. When a liquid nonionic surfactant is sprayed 
onto a composite material prepared in accordance with the invention, 
consisting for example of 15-20% by weight of carrier salt and 80-85% by 
weight of base powder, the probability of nonionic surfactant droplets 
encountering base powder rather than carrier salt is high and a rather 
poor uptake of nonionic surfactant would be expected, because the 
absorptivity of the carrier salt would not be utilised to its fullest 
extent. Surprisingly, however, the absorptivity of the composite material 
is considerably better than expected and, for example, a mixture having 
the typical proportions given above will take up about 5% by weight of 
nonionic surfactant without problems, indicating that the carrier salt is 
in fact operating virtually at full efficiency. It might also be expected 
that spraying of these relatively high levels of nonionic surfactant onto 
the composite mixture would give a sticky, poorly flowing product, but 
this has not been observed. 
When the carrier salt is Burkeite, which is anhydrous, further problems 
might be expected because the two slurries have to be spray-dried to very 
different powder moisture contents: the base powder will normally contain 
about 10 to 18% by weight of water, while Burkeite carrier material does 
not contain more than about 2% by weight of water. The major part of the 
water in the base powder, however, is present in bound form in builder 
salts--notably sodium tripolyphosphate hexahydrate or sodium 
aluminosilicate--and the free moisture content is comparable to that of 
the Burkeite carrier material. Consequently, no problems have been 
experienced in this regard. 
THE CARBONATE SLURRY 
The carbonate slurry contains, as essential ingredients, sodiu carbonate, 
water and a polycarboxylate crystal growth modifier. Optionally sodium 
sulphate and/or sodium bicarbonate may be present depending on the porous 
carrier salt desired. Minor amounts of other materials may also be 
included as explained below. 
It is essential that the polycarboxylate crystal growth modifier be present 
in the slurry at a sufficiently early stage to influence the crystal 
growth of the carbonate carrier salt. It must accordingly be incorporated 
in the slurry not later than the time at which the sodium carbonate is 
added. If sodium sulphate and/or sodium bicarbonate is or are present, the 
crystal growth modifier is preferably incorporated not later than the 
addition of both the sodium carbonate and the other salt(s). 
In batch slurry-making, there is no difficulty in arranging for the 
ingredients to be added in the appropriate order. In continuous 
slurry-making processes all components are added substantially 
simultaneously, but once the start-up period is over the inorganic salts 
will in practice always encounter a slurry containing some crystal growth 
modifier. 
The water used to prepare the carbonate slurry is preferably relatively 
soft. Desirably water of hardness not exceeding 15.degree. (French) is 
used. 
The sodium carbonate used in the carbonate slurry may be of any type. 
Synthetic light soda ash has been found to be especially preferred; 
natural heavy soda ash is intermediate, while synthetic granula soda ash 
is the least preferred raw material. All grades of sodium sulphate are 
suitable for use in the invention, provided that they are not heavily 
contaminated with other salts such as salts of calcium or magnesium. 
If the carrier salt is Burkeite, the extent of its formation in the slurry 
will of course depend on the ratio of sodium carbonate and sodium sulphate 
present. This must be at least 0.03:1 (by weight) in order for the 
resulting spray-dried material to have a useful level of porosity; and it 
is preferably at least 0.1:1 and more preferably at least 0.37:1, this 
latter figure representing the stoichiometric ratio for Burkeite 
formation. Thus it is preferred that as much as possible of the sodium 
sulphate present be in the form of Burkeite. Any excess sodium carbonate 
present will itself be in a crystal-growth-modified form. 
The stoichiometric weight ratio for sodium sesquicarbonate formation 
(sodium carbonate: sodium bicarbonate) is 1.26:1. During spray-drying some 
dehydration of sesquicarbonate occurs, to produce bicarbonate and 
carbonate; and some decomposition of bicarbonate to carbonate occurs. 
Furthermore, crystallisation in the slurry may not always be complete, so 
the yield of sesquicarbonate may be as low as 50% of theoretical. 
Preferably the weight ratio of sodium carbonate to sodium bicarbonate used 
in preparing a sesquicarbonate slurry is within the range of from 1.5:1 to 
1:1. 
The preferred order of addition of the salts to a Burkeite slurry is for 
sodium sulphate to be added before sodium carbonate. This has been found 
to give a higher yield of Burkeite and the Burkeite thus formed appears to 
have a higher useful porosity. In this preferred method, the crystal 
growth modifier should be added to the slurry either before the addition 
of both salts, or after the addition of the sodium sulphate ad before the 
addition of the sodium carbonate. 
Similar considerations apply to the use of crystal-growth-modified sodium 
sesquicarbonate. 
The polycarboxylate crystal growth modifier is an organic material 
containing at least three carboxyl groups in the molecule but we have 
found that it cannot be generically defined further in purely structural 
terms; it is also difficult to pedict how much will be required. It can, 
however, be defined functionally with reference to Burkeite crystal growth 
modification, as an organic material having three or more carboxyl groups 
in the molecule, which, when incorporated at a suitable level in a slurry 
to which sodium carbonate and sodium sulphate in a weight ratio of at 
least 0.3:1 are subsequently or simultaneously added, gives on a drying 
powder having a pore size distribution, as measured by mercury 
porosimetry, of at least 300 cm.sup.3 of pores &lt;3.5 .mu.m per kg of 
powder. 
This porosity figure, measured by the recognised technique of mercury 
porosimetry, has been found to correlate well with the capacity to take up 
and retain liquid detergentt components such as nonionic surfactants. 
For the purposes of selecting a crystal growth modifier on the basis of 
pore size distribution, it is necessary to use a simple slurry containing 
only sodium sulphate, sodium carbonate, the crystal growth modifier and 
water, because the presence of other materials will influence the 
porosity. This model system can then be used to select a crystal growth 
modifier for use in more complex slurries where other materials may be 
present, and/or for use in modifying the crystal growth of other carbonate 
salts, for example, sodium carbonate itself or sodium sesquicarbonate. 
As hinted above, the carbonate slurry for use in the process of the present 
invention may advantageously contain minor amounts of other components. A 
small amount of anionic surfactant, for example, increases powder porosity 
and increases slurry stability; a small amount of nonionic surfactant 
improves slurry pumpability and atomisation; and sodium silicate reduces 
the friability of the carrier material and aids in handling. 
The crystal growth modifier is a polycarbonate. Monomeric polycarboxylates, 
for example, salts of ethylenediaminetetraacetic acid, nitrilotriacetic 
acid and citric acid, may be used but the levels required are rather high, 
for example, 5 to 10% by weight based on the total amount of sodium 
carbonate and, if present, sodium sulphate and/or sodium bicarbonate. 
Preferred polycarboxylate crystal growth modifiers used in the invention 
are polymeric polycarboxylates. Amounts of from 0.1 to 20% by weight, 
preferably from 0.2 to 5% by weight, based on the total amount of sodium 
carbonate and, if present, sodium sulphate and/or sodium bicarbonate, are 
generally sufficient. 
The polycarboxylate crystal growth modifier preferably has a molculer 
weight of at least 1000, advantageously from 1000 to 300,000, especially 
from 1000 to 250,000. Powders having especially good dynamic flow rates 
may be prepared if the carbonate slurry incorporates polycarboxylate 
crystal growth modifiers having molecular weights in the 3000 to 100,000 
range, especially 3500 to 70,000 and more especially 10,000 to 70,000. All 
molecular weights quoted herein are those provided by the manufacturers. 
Preferred crystal growth modifiers are homopolymers and copolymers of 
acrylic acid or maleic acid. Of especial interest are polyacrylates, 
acrylic acid/maleic acid copolymers, and acrylic phosphinates. 
Suitable polymers, which may be used alone or in combination, include the 
following: 
salts of polyacrylic acid such as sodium polyacrylate, for example Versicol 
(Trade Mark) E5, E7, and E9b ex Allied Colloids, average molecular weights 
3500, 27,000 and 70,000; Narlex (Trade Mark) LD 30 and 34 ex National 
Adhesives and Resins Ltd, average molecular weights 5000 and 25,000 
repsectively; Acrysol (Trade Mark) LMW-10, LMW-20, LMW-45 and A-IN ex Rohm 
& Haas, average molecular weights 1000, 2000, 4500 and 60,000; and Sokalan 
(Trade Mark) PAS ex BASF, average molecular weight 250,000; 
ethylene/maleic acid copolymers, for example, the EMA (Trade Mark) series 
ex Monsanto; 
methyl vinyl ether/maleic acid copolymers, for example, Gantrez (Trade 
Mark) AN119 ex GAF Corporation; 
acrylic acid/maleic acid copolymers, for example, Sokalan (Trade Mark) CP5 
and CP7 ex BASF; and 
acrylic phosphinates, for example, the DKW range ex National Adhesives and 
Resins Ltd or the Belsperse (Trade Mark) range ex Ciba-Geigy AG, as 
disclosed in EP No. 182 421 A (Unilever). 
Mixtures of any two or more crystal growth modifiers may if desired be used 
in the compositions of the invention. 
The carbonate slurry will generally contain from 45 to 60% by weight of 
water. 
Slurry-making conditions may be chosen to maximise the yield of modified 
crystals obtained. Sodium carbonate and Burkeite slurries are best 
prepared at relatively high temperatures, preferably above 80.degree. C., 
more preferably from 85.degree. to 95.degree. C.; while a sodium 
sesquicarbonate slurry is best prepared at a temperature not exceeding 
65.degree. C., preferably from 50.degree. to 60.degree. C., in order to 
minimise decomposition of the sodium bicarbonate present. 
On drying a slurry containing crystal-growth-modified Burkeite, which is an 
anhydrous material, the double salt survives unchanged in the dried 
powder. Crystal-growth-modified sodium carbonate monohydrate and sodium 
sesquicarbonate will generally lose some water of crystallisation on 
drying, depending on the drying conditions, but this does not adversely 
affect the porosity and indeed may introduce further useful porosity. 
THE BASE POWDER SLURRY 
The base powder slurry will generally contain all ingredients desired in 
the final product that are sufficiently heat-stable to undergo 
spray-drying. It will always contain one or more anionic and/or nonionic 
surfactants and one or mlore detergency builders. 
Anionic surfactants are well known to those skilled in the detergents art. 
Examples include alkylbenzene sulphonates, particularly sodium linear 
C.sub.8 -C.sub.15 alkylbenzene sulphonates having an average chain length 
of C.sub.11 -C.sub.13 ; primary and secondary alcohol 
sulphates,particularly sodium C.sub.12 -C.sub.15 primary alcohol 
sulphates; olefin sulphonates; alkane sulphonates; and fatty acid ester 
sulphonates. 
It may also be desirable to include one or more soaps of fatty acids. The 
soaps which can be used are preferably sodium soaps derived from naturally 
occurring fatty acids, for example the fatty acids from coconut oil, beef 
tallow, sunflower or hardened rapeseed oil. 
The base powder slurry may also include one or more nonionic surfactants, 
in addition to the nonionic surfactant to be sprayed on in step (iii) of 
the process of the invention. Nonionic surfactants included in the base 
powder slurry will be of a type that does not give rise to unacceptable 
levels of tower emission, and will generally be present only at relatively 
low levels. 
Examples of suitable nonionic surfactants are the primary and secondary 
alcohol ethoxylates, especially the C.sub.12 -C.sub.15 primary and 
secondary alcohols ethoxylated with an average of from 5 to 20 moles of 
ethylene oxide per mole of alcohol. 
The sodium carbonate present in the carbonate-based carrier salt acts as a 
detergency builder, but will not generally be present in a sufficient 
amount to provide adequate building. Preferred builders for inclusion in 
the base powder slurry include phosphates, for example, orthophosphates, 
pyrophosphates and (most preferably) tripolyphosphates. Non-P builders 
that may be present include, but are not restricted to, sodium carbonate, 
crystalline and amorphous aluminosilicates, soaps, sulphonated fatty acid 
salts, citrates, nitrilotriacetates and carboxymethyloxsuccinates. 
Polymeric builders, for example, polycarboxylates such as polyacrylates, 
acrylic/maleic copolymers and acrylic phosphinates, may also be present, 
generally but not exclusively to supplement the effect of another builder 
such as sodium tripolyphosphate or sodium aluminosilicate. The polymers 
listed previously as crystal rowth modifiers generally have builder 
efficacy and any of these may with advantage also be included in the base 
powder slurry. 
Other ingredients that may be present in the base powder slurry include 
alkali metal silicates, antideposition agents, antiincrustation agents and 
fluorescers. 
The water content of the base powder slurry will typically be in the range 
of from 30 to 55% by weight, preferably from 35 to 50% by weight. In the 
process of the invention the slurry will be dried to a total moisture 
content, for example, of from 10 to 18% by weight, but the free moisture 
content will be much smaller, and of a similar order of magnitude to that 
of the carbonate-based carrier salt. 
SPRAY-DRYING PROCESS CONDITIONS 
In the process of the invention, the carbonate slurry and the base powder 
slurry are sprayed simultaneously into the same spray-drying tower. The 
relative quantities of the two slurries sprayed in may easily be chosen so 
that the final product contains the solid ingredients in the desired 
ratio: a carbonate-based carrier salt content in the composite spray-dried 
powder of from 5 to 30% by weight, preferably from 10 to 25% by weight, is 
suitable having regard for the amount of liquid detergent component to be 
incorporated subsequently. 
The base powder slurry is preferably spray-dried countercurrently in a 
conventional manner: the slurry is sprayed downwardly from a position 
ranging from around mid-height to the top of the tower, while hot air is 
blown upwardly into the tower from a position at or near the bottom. If 
desired, the slurry may be spray-dried concurrently, that is to say, with 
the slurry spray and the hot air entering the the tower together and 
flowing downwards, but that drying mode is less favoured because it is 
thermally less efficient and also tends to produce a less dense and finer 
powder. The slurry may also be dried using a combination of concurrent and 
countercurrent modes: any desired airflow pattern may be used. 
The position at which the carbonate slurry is sprayed in, and the spray 
direction, are not critical. In a tower operating in the preferred 
countercurrent mode mentioned above, the carbonate slurry may be sprayed 
in from a level higher, lower or the same as the level from which the base 
powder slurry is sprayed in. In general, a relatively high spray-in 
position for the carbonate slurry is preferred in order to ensure adequate 
drying: preferably the carbonate slurry is sprayed in from a position not 
more than 2 m below the level at which the base powder slurry is sprayed 
in. If the level of spray-in of the carbonate slurry is the same as or 
lower than that of the base powder slurry, the carbonate slurry may 
advantageously be sprayed upwardly, and this is strongly preferred when 
the Burkeite slurry spray-in level is lower than the base powder slurry 
spray-in level. It is also within the scope of the invention for either or 
both slurries to be sprayed from more than one level. 
Three specific spray-in arrangements have been investigated: 
(a) spraying the carbonate slurry downwardly from a position at the same 
level as the spray-in of base powder slurry; 
(b) spraying the carbonate slurry upwardly from a position near the bottom 
of the tower; 
(c) spraying the carbonate slurry upwardly from a position 0.5-2 m below 
the level of spray-in of the base powder slurry. 
Of the three arrangements, (a) and (c) were found to be better than (b). 
The product of the co-spray-drying process, on examination by scanning 
electron microscopy, has been found to consist of intimately mixed 
agglomerates of base powder and crystal-growth-modified carbonate-based 
carrier salt. 
TREATMENT WITH LIQUID DETERGENT COMPONENT 
In the next stage of the process of the invention, the composite 
spray-dried powder is treated with a liquid detergent component. This term 
includes components that require liquefaction by melting or dissolving in 
a solvent, as well as materials liquid at room temperature. The liquid 
component is preferably applied to the composite granules by spraying 
while the granules are agitated in apparatus, for example, a rotating 
drum, that continually provides a changing surface of powder to the 
sprayed liquid. The spray nozzle is advantageously angled so that liquid 
that penetrates the powder curtain falls on further powder rather than the 
shell of the drum itself. 
During the spraying process the temperature of the powder may range, for 
example, from 30.degree. to 95.degree. C. The powder generally leaves the 
spray-drying tower at an elevated temperature, and this may be 
advantageous when the component to be sprayed on has to be melted. 
The amount of liquid detergent component to be sprayed on will depend on 
the content of carbonate-based carrier salt in the composition; or 
alternatively it may be said that the amount of carbonate-based carrier 
salt included in the spray-dried powder is chosen to accommodate the 
desired amount of liquid detergent component(s) in the final composition. 
Preferably the amount of liquid detergent component is from 5 to 40% by 
weight based on the total of liquid detergent component and 
carbonate-based carrier salt: this is approximately equivalent to a range 
of 5 to 67% by weight based on the carbonate-based carrier salt alone. 
The liquid detergent component may be any ingredient that may 
advantageously be carried on a porous carbonate-based carrier salt: the 
term "detergent component" does not imply surface activity. However, in a 
preferred embodiment of the invention this component is a nonionic 
surfactant. 
Nonionic surfactants preferably used in the process and compositions of the 
invention are the primary and secondary alcohol ethoxylates, especially 
the C.sub.12 -C.sub.15 primary and second alcohols ethoxylated with an 
average of from 3 to 20 moles of ethylene oxide per mole of alcohol. The 
use of crystal-growth-modified carbonate-based carrier material is 
especially advantageous for nonionic surfactants having an average degree 
of ethoxylation of 10 or below, which are generally liquid at room 
temperature and often cannot be spray-dried because they give rise to 
unacceptable levels of tower emission ("blue smoke" or "pluming"). 
OTHER POST-TREATMENTS 
It will generally be desirable to add to the powder obtained from the 
nonionic spray-on stage (iii) various further ingredients, both liquid and 
solid, that are not suitable for spray-drying or that interfere with the 
spray-drying process. Examples of such ingredients are enzymes; bleaches, 
bleach precursors, or bleach activators; inorganic salts such as sodium 
sulphate, as described and claimed in EP No. 219 328A (Unilever); or 
sodium silicate as described and claimed in our copending Application Nos. 
86 08291 filed on Apr. 4, 1986 and 86 09042 and 86 09043 filed on Apr. 14, 
1986; lather suppressors; perfumes; dyes; and coloured noodles or 
speckles. Further examples of ingredients best incorporated by postdosing 
will readily suggest themselves to the skilled detergent formulator. 
PRODUCTS OF THE INVENTION 
Phosphate-built powders prepared in accordance with the invention may 
typically contain the following amounts of the following ingredients: 
______________________________________ 
weight % 
______________________________________ 
Surfactants (anionic, nonionic, 
5-40 
cationic, zwitterionic) 
Sodium tripolyphosphate 
5-40 
Sodium carbonate (in carrier salt) 
1-10 
Sodium carbonate (other) 
0-10 
Sodium sulphate or sodium bicarbonate 
0-25 
(in carrier salt) 
Sodium sulphate (other) 
0-30 
Crystal growth modifier 
0.05-5 
(polymeric polycarboxylate) 
Sodium silicate 0-15 
Bleach ingredients 0-30 
Enzyme, lather suppressor etc 
0-10 
______________________________________ 
Low or zero-phosphate aluminosilicate-built powders prepared in accordance 
with the invention may typically contain the following amounts of the 
following ingredients: 
______________________________________ 
weight % 
______________________________________ 
Surfactants (anionic, nonionic, 
5-40 
cationic, zwitterionic) 
Sodium aluminosilicate 
10-60 
Sodium tripolyphosphate 
0-25 
Sodium orthophosphate 0-20 
Sodium nitrilotriacetate 
0-20 
Sodium carbonate (in carrier salt) 
1-10 
Sodium carbonate (other) 
0-10 
Sodium sulphate or sodium 
0-25 
bicarbonate (in carrier salt) 
Sodium sulphate (other) 
0-30 
Crystal growth modifier 
0.05-10 
(polymeric polycarboxylate) 
Sodium silicate 0-10 
Bleach ingredients 0-30 
Enzyme, lather suppressor etc 
0-10 
______________________________________

EXAMPLES 
The invention is illustrated by the following non-limiting Examples, in 
which parts and percentages are by weight unless otherwise stated. 
Examples 1 to 5 
A Burkeite slurry was prepared to the following composition: 
______________________________________ 
parts 
______________________________________ 
Sodium polyacrylate (molecular 
2.0* 
weight 25 000) 
Sodium sulphate 65.5 
Sodium carbonate 24.5 
Nonionic surfactant 1.0 
Sodium alkaline silicate 
4.5 
Softened water 114.0 
211.5 
______________________________________ 
*2.2% based on sodium sulphate + sodium carbonate. The sodium carbonate t 
sodium sulphate ratio was 0.37:1 (stoichiometric). 
The order of addition of ingredients to the crutcher was as follows: water 
to 85.degree. C., sodium polyacrylate (crystal growth modifier), sodium 
sulphate, sodium carbonate, sodium silicate, nonionic surfactant. 
In another crutcher a base powder slurry was prepared to the following 
composition: 
______________________________________ 
parts 
______________________________________ 
Anionic surfactant (linear 
9.0 
alkylbenzene sulphonate) 
Nonionic surfactant 1.0 
Sodium tripolyphosphate 
21.5 
Sodium alkaline silicate 
5.5 
Sodium polyacrylate (molecular 
2.7 
weight 25 000) 
Minor ingredients (fluorescer, 
0.8 
antiredeposition agent etc) 
Water 40.0 
80.5 
______________________________________ 
In a control experiment (Comparative Example A), a base powder slurry 
similar to that above but additionally containing 10.0 parts of sodium 
sulphate was spray-dried to a powder moisture content of 8.0 parts. In 
Examples 1 to 3, base powder slurry and Burkeite slurry were co-sprayed 
using the different nozzle arrangements described previously, as follows: 
Example 1: arrangement of FIG. 1, 
Example 2: arrangement of FIG. 2, 
Example 3: arrangement of FIG. 3. 
The Burkeite slurry was sprayed in an amount corresponding to 10 parts of 
Burkeite per 48.5 parts of base powder (40.5 parts solids, 8 parts 
moisture). 
In each experiment the tower inlet temperature was 350.degree. C. and the 
outlet temperature was 95.degree.-105.degree. C. The powders were 
spray-dried to a moisture content of 14-16%. 
Each spray-dried product (58.5 parts) was then sprayed with 3 parts of 
liquid nonionic surfactant. The following ingredients were then postdosed: 
______________________________________ 
parts 
______________________________________ 
TAED granules 4.6 
Sodium carbonate (heavy ash) 
4.0 
Sodium perborate tetrahydrate 
8.0 
Minor ingredients (enzyme, bleach 
3.5 
stabilizer, lather suppressor etc) 
Sodium sulphate 18.4 
100.0 
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A second control powder B containing a postdosed nonionic 
surfactant/Burkeite adjunct was also prepared as follows. A base powder 
was prepared by spray-drying a base powder slurry as used in Examples 1, 2 
and 3, and the same materials as in those Examples (TAED granules, sodium 
carbonate, sodium perborate, minor ingredients, sodium sulphate) were 
postdosed, plus 13.0 parts of an adjunct prepared by spray-drying a 
Burkeite slurry (as in Examples 1-3) to form 10.0 parts of Burkeite, and 
then spraying 3.0 parts of nonionic surfactant onto the Burkeite. The 
control powder B thus had exactly the same chemical composition as the 
final powders of Examples 1-3, but the nonionic surfactant was carried on 
an adjunct rather than sprayed on to the whole powder. 
Some properties of the powders at various stages in the process are shown 
in the Table following Example 5, in which 
"BD" denotes bulk density (g/liter), 
"DFR" denotes dynamic flow rate (ml/s). 
Example 4 
A sodium sesquicarbonate slurry was prepared to the following composition: 
______________________________________ 
Parts 
______________________________________ 
Sodium polyacrylate (molecular weight 25 000) 
2.0* 
Sodium bicarbonate 40.0 
Sodium carbonate 40.0 
Nonionic surfactant 1.0 
Sodium alkaline silicate 4.5 
Softened water 103.0 
190.5 
______________________________________ 
*2.5% based on sodium bicarbonate + sodium carbonate. 
The order of addition of ingredients to the crutcher was as follows: water 
to 60.degree. C., sodium polyacrylate (crystal growth modifier), sodium 
bicarbonate, sodium carbonate, sodium silicate, nonionic surfactant. 
In another crutcher a base powder slurry was prepared to the composition 
given in Examples 1-3. 
Base powder slurry and sodium sesquicarbonate slurry were co-sprayed using 
the nozzle arrangement shown in FIG. 2, the sesquicarbonate slurry being 
sprayed in at an amount corresponding to 10 parts of sesquicarbonate per 
48.5 parts of base powder (40.5 parts solids, 8 parts moisture). 
Spray-drying conditions were as in Examples 1-3. 
The powder was sprayed with nonionic surfactant, and other ingredients were 
postdosed, as in Examples 1-3. Some properties of the powder at various 
stages in the process are shown in the Table following Example 5. 
Example 5 
A sodium carbonate slurry was prepared by mixing sodium carbonate (64 parts 
by weight) with an aqueous solution (64 parts by weight) made up of 62 
parts of softened water and 2 parts (3.1% based on the sodium carbonate) 
of sodium polyacrylate (molecular weight 25,000).The temperature of the 
aqueous solution was 80.degree. C. 
The slurry was co-sprayed with a base powder slurry using the same 
compositions and conditions as in Example 4, with sodium carbonate 
substituted for sesquicarbonate. The powder was treated in the same way as 
in Example 4, and powder property data are shown in the Table. 
__________________________________________________________________________ 
EXAMPLE 1-5 
Spray-dried powder + 
Final powder 
Final powder 
Spray-dried powder 
nonionic surfactant 
(fresh) 
(24 hours) 
Example 
BD DFR BD DFR BD DFR BD DFR 
__________________________________________________________________________ 
A 430 90 435 80 570 
80 574 
86 
1 456 109 440 83 594 
109 599 
104 
2 402 114 414 80 588 
114 600 
110 
3 494 100 514 100 644 
92 646 
100 
B 400 114 440 114 620 
110 630 
110 
4 440 100 455 95 580 
105 590 
110 
5 457 105 470 100 605 
110 630 
110 
__________________________________________________________________________ 
Examples 6 & 7 
The following Examples illustrate how base powders prepared by the process 
of the invention and containing co-sprayed polymer-modified Burkeite can 
take up higher levels of nonionic surfactant, without detriment to their 
flow properties, than can control base powders not containing co-sprayed 
Burkeite. In Comparative Examples A, C and D, liquid nonionic surfactant 
was sprayed, in the amount given in the Table (in parts), onto the 
comparative spray-dried base powder mentioned previously under Comparative 
Example A (58.5 parts, including 10.0 parts of sodium sulphate and 8.0 
parts of moisture). In Examples 2, 6 and 7, the nonionic surfactant was 
sprayed onto the powder prepared as described previously under Example 2 
(48.5 parts, including 10.0 parts co-sprayed polymer-modified Burkeite and 
8.0 parts moisture). The results are shown in the Table and illustrate a 
substantial difference in flow after 24 hours' weathering. 
______________________________________ 
Sprayed-on Stored powder 
nonionic Fresh powder 
(24 hours) 
Example surfactant BD DFR BD DFR 
______________________________________ 
A 3.0 435 80 440 85 
C 4.0 430 75 445 80 
D 5.0 400 50 430 65 
2 3.0 414 80 420 110 
6 4.0 420 80 424 100 
7 5.0 390 60 430 90 
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