[0001] This invention relates to the manufacture of detergent granules by dry neutralisation,
in particular to a process for the dry neutralisation of surfactant acid with Sodium
Carbonate to form detergent granules comprising anionic non-soap surfactant.
BACKGROUND
[0002] Detergent granules are normally manufactured as agglomerates of smaller particles.
This agglomeration can be achieved by spray drying, mixing, or a combination of those
processes. Many detergent granules comprise non-soap anionic surfactants, for example
alkyl benzene sulphonate. Such granules have been prepared by
in-situ neutralisation of the acid precursor of the non-soap anionic surfactant, referred
to hereafter as "surfactant acid" with a solid alkali salt, usually Sodium Carbonate.
[0003] GB 1 369 269 discloses a process for the neutralisation of synthetic organic anionic detergent
acids, such as straight chain alkyl benzene sulphonic acid, by mixing the acid with
an excess of powdered Sodium Carbonate in a modified mixer with a cutting arrangement,
for example a Lödige ploughshare mixer. A builder and/or filler salt is taught to
be added with the Sodium Carbonate in order to make the product more free flowing.
The choppers or cutters in the mixer are used during addition of the acid. Examples
1 and 2 include a sodium tripolyphosphates in the dry mix. The powders produced are
free flowing. Example 3 uses no sodium tripolyphosphate but the product requires pulverisation
and is not described as free flowing. A problem with this disclosure is that it is
now desirable to exclude phosphate from the granule, but this document does not teach
an effective process for its elimination.
[0004] GB 2 221 695 describes a dry neutralisation process for preparation of detergent powder of high
bulk density in a high speed mixer granulator, with a stirring and a cutting action.
In most of the examples, zeolite or Sodium Tripolyphosphate is used in addition to
Sodium Carbonate.
In examples 26 to 29, very high levels of Sodium Carbonate are used and a special
calcite flow aid is dosed at 4% to assist with the granulation. Despite this, the
flow properties of example 26 are very poor and addition of Sodium Tripolyphosphate
is taught as a remedy for this problem. A problem with this process is that the use
of a flow aid is a major process complication and it is now desirable to exclude phosphate
from the granule.
[0005] WO 2002/28454 describes a dry neutralisation process carried out in a horizontal thin-film evaporator
drier. Use of small particle size Sodium Carbonate is taught to reduce the amount
of unneutralised surfactant acid in the resulting product. Such unneutralised material
is known to be undesirable as it continues to react with the Sodium Carbonate and
causes powder caking. In the examples, zeolite is also added. This addition would
reduce the level of anionic surfactant in the detergent granule.
Furthermore, it is now desirable to be able to eliminate use of zeolite from a detergent
granule if it is not essential in the formulation.
[0006] US 7 053 038 describes a dry neutralisation process carried out in a gas fluidisation granulator
using small particle size Sodium Carbonate and an inorganic acid, such as sulphuric
acid. Both zeolite and sodium tripolyphosphate are included in all the examples.
[0007] EP 1 534 812 discloses dry neutralisation of preformed spray dried particles comprising a carbonate
salt and polyacrylate. The process is carried out under low shear conditions in order
to avoid agglomeration. In all of the examples, the carbonate salt is the Burkeite
double salt formed when Sodium Carbonate and sodium sulphate are spray dried together.
These particles are too strong to be used in the process of the present invention.
As further explained later this process does not make habit modified Sodium Carbonate.
[0008] EP 0 221 776 describes a process to spray dry Sodium Carbonate and a crystal growth modifier to
make, so called, habit modified carbonate granules. The crystal growth modifier is
preferably polymeric polycarboxylate. The patent describes the manufacture of habit
modified Burkeite in the majority of the examples. Only example 1 crystal habit modifies
Sodium Carbonate itself.
[0009] Habit modified Sodium Carbonate is also spray dried for use as a carrier granule
in
WO 2006/081930. Polyaspartates are used in place of the polycarboxylates of
EP 0 221 776.
[0010] Throughout this specification habit modified Sodium Carbonate is a term used to encompass
such prior art materials. The term does not include habit modified Burkeite, although
low concentrations of Burkeite could conceivably be included in admixture with the
desired habit modified Sodium Carbonate provided that the resulting admixture remains
characterised as described below.
[0011] There remains a need for a process to manufacture detergent granules by dry neutralisation,
that does not require the use of additives such as zeolite, Sodium Tripolyphosphate,
or flow aids to facilitate satisfactory granulation and at the same time provides
the required conversion of surfactant acid to surfactant.
[0012] It is an object of the present invention to provide an improved process for the manufacture
of detergent granules comprising non-soap anionic surfactant by dry neutralisation.
It is also an object to provide detergent granules comprising Sodium Carbonate and
exceptionally high levels of non-soap anionic surfactant, which exhibit improved storage
and handling properties.
SUMMARY OF THE INVENTION
[0013] According to the present invention there is provided a process for the manufacture
of detergent granules comprising anionic non-soap surfactant, the process comprising
the step of dry neutralisation of surfactant acid with habit modified Sodium Carbonate.
[0014] The invention also provides detergent granules comprising at least 30 wt% anionic
surfactant comprising a major part of anionic non-soap surfactant and habit modified
Sodium Carbonate, and with less than 10 wt%, preferably zero, zeolite, obtainable
by the process.
DETAILED DESCRIPTION OF THE INVENTION
The habit modified Sodium Carbonate (HMC)
[0015] Habit modified Sodium Carbonate is a crystal growth modified Sodium Carbonate, which
comprises a mixture of Sodium Carbonate and polymer. Its manufacture is, for example,
described in
EP 0 221 776 and
WO 2006/081930. It is not the same thing as habit modified Burkeite; the double salt of Sodium Carbonate
and Sodium Sulphate.
[0016] It is essential that the polymer used as crystal growth modifier is present when
crystallisation of the habit modified Sodium Carbonate occurs, that is to say, it
must be incorporated not later than the Sodium Carbonate.
[0017] Habit modified Sodium Carbonate is further characterised by its specific surface
area, measured by nitrogen adsorption. The specific surface area ("SSA") of the Sodium
Carbonate is measured by nitrogen absorption according to ASTM D 3663-78 standard
based upon the
Brunauer, Emmett, and Teller (BET) method described in J. Am. Chem. Soc. 60, 309 (1938). We used a Gemini Model 2360 surface area analyzer (available from Micromeritics
Instrument Corp. of Norcross, Ga.).
The Habit modified Sodium Carbonate is characterised by having a specific surface
area (SSA) of 5 m
2/g or greater, preferably 8 m
2/g or greater, even more preferably 10 m
2/g or greater.
[0018] The pore volume in pores less than 2 micron may further characterise the habit modified
Sodium carbonate. This is measured by a conventional mercury porosimetry method. Pore
volumes of 0.3 ml/g or greater are advantageous.
[0019] An alternative characterisation of the habit modified Sodium Carbonate, comprising
polymer and Sodium Carbonate, is to use it in the process of claim 1 with sulphonic
acid and to determine the maximum Sodium Sulphonate anionic non-soap surfactant levels
achievable before over-granulation occurs. Over-granulation means that the discrete
detergent granules begin to coalesce into a sticky mass and it is no longer possible
to discharge them as a free flowing product without adding flow aid or other solid
materials such as Zeolite or Sodium Tripolyphosphate. If the anionic Sodium Sulphonate
surfactant level achieved is greater than 30 wt%, preferably greater than 35 wt%,
more preferably greater than 45 wt%, then the Sodium Carbonate is habit modified for
the purposes of this invention.
[0020] Habit modified Sodium Carbonate, herein also referred to as HMC, may be made by spray
drying, as described in
EP 0 221 776 and
WO 2006/081930. Alternative drying methods, as described in those patent applications, may also
be employed: for example, air drying, oven drying, drum drying, ring drying, freeze
drying, solvent drying, or microwave drying.
[0021] HMC can also be made by precipitation of a saturated Sodium Carbonate solution, which
further comprises a growth modifying polymer, in an evaporator, separating the precipitate;
e.g. by filtration and drying the precipitate to habit modified Sodium Carbonate.
The remaining solution is augmented with fresh Sodium Carbonate solution and polymer
solution and returned to the evaporator. The advantage of a precipitation process
over one that relies entirely on drying is that energy consumption is lower.
The polymer
[0022] An essential component of habit modified Sodium Carbonate is the polymer. Suitable
crystal growth modifying polymers may be selected from polycarboxylates. Polyaspartates
and polyaspartic acid are advantageously used due to their biodegradability.
[0023] Preferred polymeric polycarboxylate crystal growth modifiers used in the invention
are used in amounts of from 0.1 to 20 wt%, preferably from 0.2 to 5 wt%, most preferably
1 to 5 wt%, based on the total amount of Sodium Carbonate. However, higher levels
of polymer, for example, up to 60% by weight based on Sodium Carbonate, may be present
in detergent granules of the invention, or full compositions comprising the detergent
granules of the invention, for reasons other than crystal growth modification, for
example, building, structuring or antiredeposition.
[0024] The polycarboxylate crystal growth modifier preferably has a molecular weight of
at least 1000, advantageously from 1000 to 300 000, especially from 1000 to 250 000.
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 are preferred.
All molecular weights quoted herein are those provided by the manufacturers.
[0025] Preferred crystal growth modifiers are homopolymers and copolymers of acrylic acid
or maleic acid. Of especial interest are polyacrylates and acrylic acid/maleic acid
copolymers.
[0026] Suitable polymers, which may be used alone or in combination, include the following:
[0027] Salts of polyacrylic acid such as sodium polyacrylate, for example Versicol (Trade
Mark) E5 E7 and E9 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 respectively; and Sokalan (Trade Mark) PA range
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 ex BASF.
[0028] A second group of polymeric crystal growth modifiers comprises polyaspartic acids
and polyaspartates.
[0029] Preferred polymeric crystal growth modifiers in this second group have a molecular
weight of at least 1000, advantageously from 3500 to 300000, especially from 4000
to 250000. HMC is preferably prepared using polyaspartate crystal growth modifiers
having molecular weights in the 3500 to 100000 range, especially 4000 to 70000 and
more especially 5000 to 70000. All molecular weights quoted herein are those provided
by the manufacturers.
[0030] Polyaspartate is a biopolymer synthesised from L-aspartic acid, a natural amino acid.
Due in part to the carboxylate groups, polyaspartate has similar properties to polyacrylate.
One preferred type of polyaspartate is thermal polyaspartate or TPA. This has the
benefit of being biodegradable to environmentally benign products, such as carbon
dioxide and water, which avoids the need for removal of TPA during sewage treatment,
and its disposal to landfill.
[0031] TPA may be made by first heating aspartic acid to temperatures above 180°C to produce
polysuccinimide. Then the polysuccinimide is ring opened to form polyaspartate. Because
the ring can open in two possible ways, two polymer linkages are observed, an [alpha]-linkage
and a [beta]-linkage.
[0032] Amounts of from 0.1 to 20 wt% of the crystal growth modifier, preferably from 0.2
to 5 wt%, most preferably 1 to 5 wt%, based on the total amount of Sodium Carbonate
are generally sufficient to produce suitable habit modified Sodium Carbonate.
[0033] Mixtures of any two or more polymeric crystal growth modifiers may, if desired, be
used in the process and detergent granule compositions of the invention.
The Sodium Carbonate
[0034] The Sodium Carbonate used to make the habit modified Sodium Carbonate may be of any
type. Synthetic light soda ash has been found to be especially preferred; natural
heavy soda ash is intermediate, while synthetic granular soda ash is the least preferred
raw material.
The surfactant acid
[0035] The surfactant acid is an acid precursor of an anionic non-soap surfactant which,
when reacted with habit modified Sodium Carbonate will be neutralised to form the
sodium salt of the anionic surfactant. Surfactant acids in liquid, pumpable, form
are preferred.
[0036] A preferred class of anionic surfactants is alkyl aryl sulphonates. The preferred
surfactant acid is linear alkyl benzene sulphonic acid, also referred to as LAS acid
and HLAS. This surfactant acid gives a corresponding linear alkyl benzene sulphonate
(LAS) upon neutralisation. Preferably, the LAS non-soap anionic surfactant has an
alkyl chain length of C8-18, more preferably C10-16 and most preferably C12-14.
[0037] A second preferred class of anionic surfactant is the alkyl and/or alkenyl sulphuric
acid half-esters (i.e. the sulphation products of primary alcohols) which give alkyl
and/or alkenyl sulphates upon neutralisation. Among such non-soap anionic surfactants
is primary alcohol sulphate (PAS), especially PAS having a chain length of C10-22,
preferably C12-14; Coco PAS is particularly desirable.
[0038] Other suitable surfactant acids include alpha-olefin sulphonic acids, internal olefin
sulphonic acids, fatty acid ester sulphonic acids and primary sulphonic acids.
[0039] It is also possible to use combinations of surfactant acids as will be apparent to
the skilled person.
[0040] Soaps formed by the dry neutralisation of carboxylic or fatty acids may be used as
secondary anionic surfactants in admixture with the non-soap anionic surfactants.
Preferred carboxylic acids are fatty acids with 12-18 carbon atoms, such as for example
fatty acids of coconut oil, palm oil, palm kernel and tallow. The fatty acids may
be saturated or unsaturated, branched or straight chain. Mixtures of fatty acids may
be used. Fatty acids may be used at levels of up to 30 wt% based on the surfactant
acid.
[0041] The surfactant acid (or mixture of surfactant acids) may be used in a partially pre-neutralised
form without loss of the advantageous effects of the invention. In effect, the surfactant
acid is then a mixture of the surfactant acid with neutralised anionic non-soap surfactant.
Optional further ingredients present during the process
[0042] The HMC dry neutralisation process has all of the advantages and flexibility of prior
art dry neutralisation processes.
[0043] The surfactant acid may be added in admixture with other liquid components. Among
these, in addition to the fatty acids and neutralised anionic surfactant already discussed,
the most important additional component that may be added as liquids with the surfactant
acid is nonionic surfactant. This is typically added to the surfactant acid to reduce
viscosity to enable it to be added at a lower temperature.
[0044] Suitable nonionic surfactants that may be used include the primary and secondary
alcohol ethoxylates, especially the C8-C20 aliphatic alcohols ethoxylated with an
average of from 1 to 50, preferably 1 to 20, moles ethylene oxide per mole of alcohol,
and more especially the do-cis primary and secondary aliphatic alcohols ethoxylated
with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol. Non-ethoxylated
nonionic surfactants include alkylpolyglycosides, glycerol monoethers, and polyhydroxyamides
(glucamide). As discussed already neutralised anionic surfactant may be mixed with
the surfactant acid. This can have the advantage of increasing throughput of the reaction
vessel/mixer.
[0045] Other liquid additives that may be added with the anionic surfactant acid, or added
as separate liquid stream(s), include inorganic acids, such as sulphuric acid, and
hydrotropes, such as para toluene sulphonic acid.
[0046] A small amount of water, sufficient to initiate the neutralisation reaction but not
sufficient to cause substantial agglomeration, may be premixed with the surfactant
acid before the latter is introduced into the mixer, but addition of water is not
essential. If a coloured product is desired, dyestuff may conveniently be premixed
with the surfactant acid and water before addition to the mixer. The amount of water
to be added may up to about 2 wt% based on the total granule ingredients.
[0047] Additional solid may be admixed with the habit modified Sodium Carbonate. This can
be done either before or during neutralisation of the surfactant acid. Unmodified
Sodium Carbonate, i.e. soda ash, may be used in admixture with the habit modified
Sodium Carbonate. Zeolite and/or other builder materials could be added, although
they are not needed to gain the good granule properties ascribed to the use of HMC.
It is preferred to avoid use of zeolite completely, except perhaps as a final whitening
coating. A complete detergent system can nevertheless be formulated into a single
simple dry neutralised granule especially when Calcium tolerant surfactant blends
are used. Calcium tolerant surfactant blends are those single or mixed surfactants,
which do not require builders to be present for effective detergency across a normal
range of water hardness. We use the following method to test a surfactant blend for
Calcium-tolerance. First 0.7 g/L of the surfactant blend are dissolved in water containing
sufficient Calcium ions to give a French hardness of 40 (4 x 10
-3 Molar Ca
2+). Other electrolytes such as Sodium Chloride, Sodium Sulphate, and Sodium hydroxide
are then added as necessary to adjust the ionic strength to 0.05M and the pH to 10.
The adsorption of light of wavelength 540 nm through 4 mm of sample is measured 15
minutes after sample preparation. Ten measurements are made and an average value is
calculated. Calcium tolerant blends are those that give an average value of less than
0.08.
[0048] Calcium tolerant surfactant blends that may be dry neutralised include mixtures of
LAS with nonionic high EO, SLES paste and/or AOS paste.
[0049] In addition to the essential habit modified Sodium Carbonate, conventional builders
and non habit modified Sodium Carbonate may also be added to the mixer. Examples of
such builders include crystalline and amorphous alkali metal aluminosilicates, alkali
metal phosphates, and mixtures thereof. The total of habit modified Sodium Carbonate
and Sodium Carbonate should always be present in excess of the amount required for
neutralisation, in order to provide alkalinity in the product: an excess of about
10 to 15 wt% is then suitable. This represents a molar excess of 3:1 or more.
[0050] The solids present in the mixer may also include other solid ingredients desired
for inclusion in the detergent granule, for example, fluorescers; polycarboxylate
polymers; antiredeposition agents, for example, sodium carboxymethyl cellulose; or
fillers such as sodium sulphate, diatomaceous earth, calcite, kaolin or bentonite.
[0051] If desired, solid particulate surfactants, for example, alkylbenzene sulphonate and/or
alkyl sulphate in powder form, may form part of the solids charge to the mixer to
further increase the activity level of surfactant in the granule, however it is preferred
to produce all the anionic surfactant by dry neutralisation.
[0052] Other anionic surfactants that may be present in detergent granules prepared by the
process of the invention include secondary alkyl sulphates, alkyl ether sulphates,
and dialkyl sulphosuccinates. Anionic surfactants are of course well known and the
skilled reader will be able to add to this list.
The dry neutralisation process
[0053] The surfactant acid is preferably used in liquid form and advantageously it is reacted
while mixing with a molar excess of habit modified Sodium Carbonate to form a sodium
salt of the anionic surfactant, while mixing. As an alternative to use of a molar
excess of habit modified Sodium Carbonate the reaction may be done with a mixture
of habit modified Sodium Carbonate and a smaller amount of other conventional Sodium
Carbonate, such as light ash and/or Burkeite, with a corresponding reduction in the
granulation benefits of the invention. Nevertheless, if large amounts of Sodium Carbonate
are to be used this hybrid process reduces the amount of specially habit modified
raw material needed.
[0054] A wider than normal range of ratios of liquid to solid ingredients may be used in
the dry neutralisation reaction. Because the system is self structuring, no zeolite
or similar structurant is needed and the process is easy to control.
[0055] The total amount of free water that can be tolerated in the process preferably should
not amount to more than 8 wt% of the total composition, preferably not more than 4
wt%.
[0056] When habit modified Sodium Carbonate is used in the dry neutralisation process then
the resulting granule will comprise neutralised anionic surfactant together with any
excess habit modified Sodium Carbonate. The habit modified Sodium Carbonate is an
excellent substrate for additional liquid components and it also functions in the
same way as Sodium Carbonate as a buffer in a detergent composition.
The invention may thus advantageously be used to prepare detergent powders in which
Sodium Carbonate is used without any other builder present - especially if a Calcium
tolerant surfactant blend or mixture is used. To ensure the presence of significant
quantities of Sodium Carbonate in the granule substantially more habit modified Sodium
Carbonate than is required for neutralisation may be present.
[0057] A process feature known to the person skilled in the art of dry neutralisation is
that the surfactant acid should be added to the mixer sufficiently gradually so that
it will be consumed immediately and will not accumulate in the mixer in unreacted
form. We have found that this applies equally to the process using habit modified
Sodium Carbonate. The time required and preferred for addition of the surfactant acid
is of course dependent on the amount to be added, but in general addition preferably
takes place over a period of at least 1 minute, more preferably over a period of from
2 to 12 minutes, most preferably from 3 to 10 minutes.
The mixer
[0058] The process is generally not sensitive to the type of mixer used, provided intensive
mixing is applied. We have found that to obtain the full advantages of the invention
the use of a mixer with a chopping action is advantageous. The HMC starting material
has a relatively low crush strength and the mixer should be selected so that it breaks
up and rapidly provides fine, material with a consequent large total surface area
for reaction and for regranulation.
Thus, a conventional fluid bed granulator would not be preferred for the dry neutralisation
process using habit modified carbonate.
[0059] Preferably, the mixing is carried out in a mixer having and using both a stirring
action and a cutting action, most preferably these actions will be separately usable,
as described below. The cutting action is the preferred chopping action. This may
be advantageously achieved by the choice of mixer to be a high-speed mixer/granulator
having both a stirring action and a cutting action. Preferably, the high-speed mixer/granulator
has rotatable stirrer and cutter elements that can be operated independently of one
another, and at separately changeable or variable speeds. Such a mixer is capable
of combining a high-energy stirring input with a cutting action, but can also be used
to provide other, gentler stirring regimes with or without the cutter in operation.
The cutters would be off during the solids pre-mixing.
[0060] A Lödige mixer is preferred, vertical or horizontal axis cutters are desirable for
high anionic loading. Also preferred are mixers of the Fukae FS-G type manufactured
by Fukae Powtech Co Ltd., Japan; this apparatus is essentially in the form of a bowl-shaped
vessel accessible via a top port, provided near its base with a stirrer having a substantially
vertical axis, and a cutter positioned on a side wall.
[0061] The stirrer and cutter may be operated independently of one another, and at separately
variable speeds. The vessel can be cooled.
[0062] Other mixers believed to be suitable for use in the process of the invention are
the Fuji (Trade Mark) VG-C series ex Fuji Sangyo Co., Japan; and the Roto (Trade Mark)
ex Zanchetta & Co srl, Italy.
[0063] Yet another mixer found to be suitable for use in the process of the invention is
the Lödige (Trade Mark) FM series batch mixer ex Morton Machine Co. Ltd., Scotland.
This differs from the mixers mentioned above in that its stirrer has a horizontal
axis. Z blade and sigma mixers (Winkworth machinery limited) are suitable mixers having
a chopping action.
[0064] The temperature of the powder mass in the mixer should be maintained throughout at
55 °C or below, preferably below 50 °C, more preferably below 47 °C, and desirably
below 40 °C. If the temperature is allowed to rise too much, agglomeration and lump
formation may occur.
The detergent granule
[0065] The granular product of the process is a particulate solid with a bulk density in
the range 450 to 720 g/litre. The particle size distribution is generally such that
at least 50 wt%, preferably at least 70 wt% and more preferably at least 85 wt%, of
particles are smaller than 1700 microns, and the level of fines is low. No further
treatment has generally been found to be necessary to remove either oversize particles
or fines.
[0066] The product generally has excellent flow properties, low compressibility and little
tendency towards caking.
[0067] The particulate detergent granules that are the direct result of the dry neutralisation
process may have an anionic surfactant content of 25 wt% to 45 wt%, or even higher.
The absence of the need for a granulation aid such as zeolite, together with the ease
that the reaction can be driven results in the potential to achieve exceptionally
high levels of anionic surfactant in the granule. For example, greater than about
30 wt%, preferably greater than 35 wt%, even greater than 40 wt%, or over 45 wt% anionic
surfactant may be incorporated into the detergent granule. It is preferred for the
anionic surfactant to comprise less than 10 wt% soap, based on the total anionic surfactant
in the detergent granule.
[0068] The detergent granules may also comprise water in an amount of 0 to 8% and preferably
0 to 4% by weight of the granules.
[0069] The detergent granules obtained from the process are storage stable at high levels
of humidity. Thus, they can be used in a wide range of detergent products.
[0070] Desirably the detergent granules have an aspect ratio not in excess of two and more
preferably are generally spherical in order to reduce segregation from other particles
in a formulated powder detergent composition and to enhance the visual appearance
of the powder.
Further processing
[0071] If desired, further ingredients may be admixed to the detergent granules after they
have been manufactured.
[0072] The detergent granules may be admixed with anything normally used in detergent formulations.
They may be dry blended with solid materials and they may advantageously have further
liquids added into them, using their spare liquid carrying capacity. It is especially
advantageous to add conventional, or even higher than conventional, levels of perfume
this way.
[0073] Other types of non-soap surfactant, for example, cationic, zwitterionic, amphoteric
or semipolar surfactants, may also be used with the granules if desired. Many suitable
detergent-active compounds are available and are fully described in the literature,
for example, in "Surface-Active Agents and Detergents", Volumes I and II, by Schwartz,
Perry and Berch.
[0074] Soap may also be present, to provide foam control and additional detergency and builder
power. The fully formulated composition may comprise up to 8 wt% soap.
[0075] Detergent compositions including the detergent granules prepared by the process of
the invention may contain conventional amounts of other detergent ingredients, for
example, bleaches, enzymes, lather boosters or lather controllers as appropriate,
antiredeposition agents such as cellulosic polymers; anti incrustation agents, perfumes,
dyes, shading dyes, fluorescers, sodium silicate; corrosion inhibitors including silicates;
inorganic salts such as sodium sulphate, enzymes; coloured speckles; foam controllers;
and fabric softening compounds. The detergent granule may if desired be mixed with
other organic or inorganic builders, typically supplied in the form of granules of
either pure builder or mixtures of builder and other ingredients. Especially preferred
organic builders are acrylic polymers, more especially acrylic/maleic copolymers,
suitably used in amounts of from 0.5 to 15 wt%, preferably from 1 to 10wt%. Such polymers
may also fulfil the function of the habit modifying polymer.
[0076] The skilled detergent formulator can decide which ingredients are suitable for admixture
in the mixer, and which are not.
[0077] The detergent granules may be mixed with another powder obtained from any conventional
detergent production process including spray drying or non spray drying processes.
For convenience, such other powder is hereinafter called a base powder. As the detergent
granules produced by the present invention may be admixed with such other powders,
a significant degree of formulation flexibility is obtained and the level of active
material in the fully formulated composition may be very high without an unnecessary
increase in builder levels.
[0078] The total amount of surfactant present in the detergent composition is suitably from
to 5 to 40 wt%, although amounts outside this range may be employed as desired.
[0079] The detergent granules may typically constitute from 30 to 100 wt% of a final fully
formulated detergent composition. Typically, the fully formulated detergent composition
incorporating the detergent granules produced by the process of the invention may
comprise from 5 to 45 wt%, preferably 10 to 35 wt% of anionic surfactant, this anionic
surfactant being derived wholly or in part from the granular product of the dry neutralisation
reaction. The process of the invention is of especial interest for the production
of detergent powders or components containing relatively high levels of anionic surfactant,
for example, 15 to 30 wt%, more especially 20 to 30 wt%. In addition, the fully formulated
detergent composition may comprise from 0 to 10 wt% of nonionic surfactant, and from
0 to 5 wt% of fatty acid soap.
[0080] Fully formulated detergent compositions, comprising other ingredients and the detergent
granules produced by dry neutralisation of habit modified Sodium Carbonate; preferably
have a bulk density of at least 400 g/l, more preferably at least 450 g/litre.
[0081] The invention will now be further described with reference to the following non limiting
examples. In the examples, in addition to the SSA, pore volume and loading tests described
above, the detergent granule properties are measured according to the following known
test protocols.
Dynamic flow rate (DFR)
[0082] This is also called flow-rate. Powder flow may be quantified by means of the dynamic
flow rate (DFR), in ml/s, measured by means of the following procedure. The apparatus
used consists of a cylindrical glass tube having an internal diameter of 35 mm and
a length of 600 mm. The tube is securely clamped in a position such that its longitudinal
axis is vertical. Its lower end is terminated by means of a smooth cone of polyvinyl
chloride having an internal angle of 15° and a lower outlet orifice of diameter 22.5
mm. A first beam sensor is positioned 150 mm above the outlet, and a second beam sensor
is positioned 250 mm above the first sensor.
[0083] To determine the dynamic flow rate of a powder sample, the outlet orifice is temporarily
closed, for example, by covering with a piece of card, and powder is poured through
a funnel into the top of the cylinder until the powder level is about 10 cm higher
than the upper sensor; a spacer between the funnel and the tube ensures that filling
is uniform. The outlet is then opened and the time t (seconds) taken for the powder
level to fall from the upper sensor to the lower sensor is measured electronically.
The measurement is normally repeated two or three times and an average value taken.
If V is the volume (ml) of the tube between the upper and lower sensors, the dynamic
flow rate DFR (ml/s) is given by the following equation:
Unconfined Compression Test (UCT)
[0084] In this test, freshly produced powder is compressed into a compact and the force
required to break the compact is measured. The powder is loaded into a cylinder and
the surface levelled. A 50 g plastic disc is placed on top of the powder and a 10
kg weighted plunger is placed slowly on top of the disc and allowed to remain in position
for 2 minutes. The weight and plunger are then removed and the cylinder removed carefully
from the powder to leave a freestanding cylinder of powder with the 50g plastic disc
on top of it. If the compact is unbroken, a second 50 g plastic disc is placed on
top of the first and left for approximately ten seconds. Then if the compact is still
unbroken a 100 g disc is added to the plastic discs and left for ten seconds. The
weight is then increased in 0.25 kg increments at 10 second intervals until the compact
collapses. The total weight (w) needed to effect collapse is noted.
Dissolution time (T90)
[0086] A 1-litre beaker is filled with 500mls of demineralised water at 20-25°C and stirred
with a magnetic stirrer adjusted to give a vortex of about 4cm. A sample of powder
is added to the water. The dissolution is measured according to solution conductivity.
The 'T90' value is the time taken to achieve 90% of the final conductivity value.
Bulk density (BD)
[0087] This is measured by taking the increase in weight of a 1 litre container when it
is filled with detergent granules and tapped lightly.
EXAMPLES
[0088] Sodium carbonate materials for use in dry neutralisation were obtained. Dense granulated
sodium carbonate (reference carbonate A) and light soda ash (reference carbonate B)
were sourced directly from Brunner Mond. Reference carbonate C and HMC 1 to 6 were
manufactured as described below.
HMC 1 - Spray dried HMC (low moisture)
[0089] HMC was prepared according to
WO 2006/081930 A1 by mixing together 29.8 kg of Sokalan CP5 solution (40% active material) with 1373.8kg
of water in a stirred tank. Into this solution was then dissolved 596.4 kg of light
Sodium Carbonate (ex Brunner Mond). The resultant solution was then spray dried in
a 2.5 m diameter spray-drying tower to a final product moisture content of 1.8 % (by
IR Balance).
HMC 2 - Spray dried HMC (high moisture)
[0090] The preparation was as for HMC 1 except that the HMC was spray dried to a final product
moisture content of 12.9 % (by IR Balance).
HMC 3 - Oven dried HMC
[0091] 0.06kg of Sokalan CP5 solution (40% active material) was mixed with 2.74 kg of water
in a stirred tank. Into this solution was then dissolved 1.2 kg of light Sodium Carbonate
(ex Brunner Mond). The resultant solution was then dried in shallow trays (solution
depth approximately 0.5cm) in an oven at 85°C.
HMC 4 - Drum dried HMC
[0092] A solution with composition by weight, 69.58% water, 0.6% Sokalan CP5 (100% active
material) and 29.82% light Sodium Carbonate (ex Brunner Mond) was dried using a 0.391m
diameter twin-drum dryer (drying time of 25.6 seconds, drum temperature 148°C).
HMC 5 - Microwave dried HMC
[0093] 1.5 g of Sokalan CP5 solution (40% active material) was mixed with 68.5 g of water
in a beaker. Into this solution was then dissolved 30g of light Sodium Carbonate (ex
Brunner Mond). The resultant solution was then dried in shallow trays (solution depth
approximately 0.5cm) in a microwave oven (Samsung MX35 1000W).
HMC 6 - Precipitated HMC
[0094] 29.8 g of Sokalan CP5 solution was dissolved in 1400 g of demin. water in glass beaker.
To this solution was added 590g of light Sodium Carbonate (ex Brunner Mond). The resultant
solution was then heated to 70°C with constant stirring and left open to atmosphere
to allow evaporation. Heating and stirring were continued until the solution volume
had reduced to approximately half its initial volume. The resultant slurry was filtered
to remove the crystals precipitated during evaporation. These crystals were then oven
dried at 85°C to produce the final product.
Reference Carbonate C - Spray dried modified Burkeite
[0095] 425.2kg of water was added to a 1m
3 mixing vessel having agitation impellers. To the water were sequentially added 25.3kg
of sodium polyacrylate solution (Sokalan PA40 ex BASF) followed by 330kg of Sodium
Sulphate. The temperature of the mixture was then raised to 60°C and agitated for
8 minutes. 123.7 kg of Sodium Carbonate (Light ash ex Brunner Mond) was then added
whilst maintaining agitation to form a slurry. The temperature of the resultant mixture
was then raised to 82°C and agitated for a further 12 minutes. 54.9kg of alkaline
silicate solution (Crystal 112 ex Ineos Silicas) was then added. The resultant 53
wt% slurry was spray-dried to form a Burkeite carrier material similar to that made
in the examples of
EP 1 534 812 (Kao).
[0096] The above prepared samples had their specific surface area (SSA) and porosity in
small pores (<2 micron diameter) measured using the BET method already described.
In addition, by dry neutralisation experiments the maximum amount of LAS acid (HLAS)
surfactant acid that could be used with the different types of Sodium Carbonate was
determined.
[0097] In Table 1 the SSA, porosity and HLAS capacity is summarised for carbonate materials
used. It can be seen that there is a correlation between SSA and the amount of surfactant
acid.
Table 1
Carbonate |
Example |
pore vol ml/g (diameter <2 micron) |
SSA (m2/g) |
LAS Capacity (gHLAS /100g carrier) |
Dense Ash |
Ref A |
0.07 |
0.46 |
9.4 |
Light Ash |
Ref B |
0.21 |
1.00 |
22.5* |
Burkeite |
Ref C |
0.48 |
3.08 |
10.0 |
Spray Dried HMC |
HMC 1 |
0.64 |
8.17 |
98.3 |
Drum Dried HMC |
HMC 4 |
0.78 |
8.69 |
80.7 |
Microwave HMC |
HMC 5 |
0.72 |
8.88 |
122.0 |
Oven Dried HMC |
HMC 3 |
0.78 |
10.86 |
157.5 |
Precipitated HMC |
HMC 6 |
0.77 |
12.36 |
135.0 |
*granulation was not possible. The product was a sticky mess, so the amount of surfactant
acid noted here is not a true granule carrying capacity. |
[0098] Throughout the examples the surfactant acid used is LAS acid: C9 to C11 Linear Alkyl
Benzene Sulphonic Acid having a mean molecular weight of 320 a purity of 97% and containing
0.8% water.
Example 1 - Neutralisation of LAS acid in Fukae mixer
[0099] 4.0 kg of HMC 1 were charged to a Fukae FS30 high shear granulator/mixer, and mixed
using an agitator speed of 200 rpm and a chopper speed of 1300 rpm. Whilst the powder
was mixing 1.8 kg of LAS acid was added at a constant rate over a period of 4 minutes
using a peristaltic pump. On completion of the addition of the LAS acid, mixing was
continued for a further 30 seconds, after which time, the solid product was discharged
from the mixer.
[0100] The granulated product was a readily soluble, free-flowing powder (flow-rate 130),
having a bulk density of 705 kg/m
3, and a dissolution time (T90) of 34 seconds.
Example 2 - Neutralisation of LAS acid in Ploughshare mixer
[0101] 12 kg of HMC 1 were charged to a Morton (130 litre) Ploughshare granulator/mixer,
and mixed using an agitator speed of 100 rpm and a chopper speed of 1000 rpm. Whilst
the powder was mixing 5.09 kg of LAS acid was added at a constant rate over a period
of 4.5 minutes using a peristaltic pump. On completion of the addition of the LAS
acid, mixing was continued for a further 30 seconds, after which time, the solid product
was discharged from the mixer.
[0102] The granulated product was a readily soluble, free-flowing powder (flow-rate 135),
having a bulk density of 532 kg/m
3, and a dissolution time (T90) of 30 seconds.
Example 3 - Neutralisation of LAS acid in Z blade mixer
[0103] 0.3 kg of HMC 1 was charged to a Winkworth (Type 2Z) z-blade mixer. Whilst the powder
was mixing 0.135 kg of LAS acid was poured in at a constant rate over a period of
4 minutes. On completion of the addition of the LAS acid, mixing was continued for
a further 30 seconds, after which time, the solid product was discharged from the
mixer.
[0104] The granulated product was a readily soluble, free-flowing powder (flow-rate 108),
having a bulk density of 496 kg/m
3, and a dissolution time (T90) of 25 seconds.
Example 4 - Neutralisation of LAS acid in high shear mixer
[0105] 1.0 kg of HMC 1 were charged to a Zanchetta RotoJunior (10 litre) high shear granulator/mixer,
and mixed using an agitator speed of 350 rpm and a chopper speed of 1350 rpm. Whilst
the powder was mixing 0.45 kg of LAS acid was added at a constant rate over a period
of 4 minutes using a peristaltic pump. On completion of the addition of the LAS acid,
mixing was continued for a further 30 seconds, after which time, the solid product
was discharged from the mixer.
[0106] The granulated product was a readily soluble, free-flowing powder (flow-rate 142),
having a bulk density of 549 kg/m
3, and a dissolution time (T90) of 32 seconds.
Example 5 - Neutralisation of LAS acid by high moisture HMC
[0107] This is essentially a repeat of Example 1, but using 4.0 kg of higher moisture HMC
2 instead of HMC 1. The HMC was charged to a Fukae FS30 high shear granulator/mixer,
and mixed using an agitator speed of 200 rpm and a chopper speed of 1300 rpm. Whilst
the powder was mixing 1.54 kg of LAS acid was added at a constant rate over a period
of 4 minutes using a peristaltic pump. On completion of the addition of the LAS acid,
mixing was continued for a further 30 seconds, after which time, the solid product
was discharged from the mixer.
[0108] The granulated product was a readily soluble, free-flowing powder (flow-rate 144),
having a bulk density of 570 kg/m
3, and a dissolution time (T90) of 34 seconds.
Example 6 - Neutralisation of HMC with a LAS acid/NI blend
[0109] 400 g of LAS acid was thoroughly mixed with 100 g of ethoxylated alcohol nonionic
surfactant (Neodol 25-7 ex Shell Chemicals) to form a liquid blend.
[0110] 1.0 kg of HMC 1 was charged to a Zanchetta RotoJunior (10 litre) high shear granulator/mixer,
and mixed using an agitator speed of 350 rpm and a chopper speed of 1350 rpm. Whilst
the powder was mixing 0.453 kg of the LAS acid/ nonionic surfactant liquid blend was
added at a constant rate over a period of 4 minutes using a peristaltic pump.
On completion of the addition of the liquid blend, mixing was continued for a further
30 seconds, after which time, the solid product was discharged from the mixer.
[0111] The granulated product was a readily soluble, free-flowing powder (flow-rate 129),
having a bulk density of 655 kg/m
3, and a dissolution time (T90) of 40 seconds.
Example 7 - Neutralisation of HMC with a LAS acid/fatty acid blend
[0112] 400 g of LAS acid was thoroughly mixed with 100 g of fatty acid (Pristerine 4916)
to form a liquid blend.
[0113] 1.0 kg of HMC 1 was charged to a Zanchetta RotoJunior (10 litre) high shear granulator/mixer,
and mixed using an agitator speed of 350 rpm and a chopper speed of 1350 rpm. Whilst
the powder was mixing 0.45 kg of the LAS acid/ fatty acid liquid blend was added at
a constant rate over a period of 4 minutes using a peristaltic pump. On completion
of the addition of the liquid blend, mixing was continued for a further 30 seconds,
after which time, the solid product was discharged from the mixer.
[0114] The granulated product was a readily soluble, free-flowing powder (flow-rate 148),
having a bulk density of 582 kg/m
3, and a dissolution time (T90) of 40 seconds.
Example 8 - Neutralisation of LAS acid in Z blade mixer
[0115] This is essentially a repeat of Example 3 using the oven dried material HMC 3 in
place of the spray dried HMC 1. 0.3 kg of oven dried HMC 3 was charged to a Winkworth
(model 2Z) z-blade mixer. Whilst the powder was mixing 0.135 kg of LAS acid was poured
at a constant rate over a period of 4 minutes. On completion of the addition of the
LAS acid, mixing was continued for a further 30 seconds, after which time, the solid
product was discharged from the mixer.
[0116] The granulated product was a readily soluble, free-flowing powder (flow-rate 111),
having a bulk density of 482 kg/m
3, and a dissolution time (T90) of 27 seconds.
Example 9 - Neutralisation of LAS acid in Z blade mixer
[0117] This is a repeat of Example 8 using more LAS acid. 0.3 kg of HMC 3 was charged to
a Winkworth (model 2Z) z-blade mixer. Whilst the powder was mixing 0.215 kg of LAS
acid was poured at a constant rate over a period of 4 minutes.
On completion of the addition of the LAS acid, mixing was continued for a further
30 seconds, after which time, the solid product was discharged from the mixer.
[0118] The granulated product was a readily soluble, free-flowing powder (flow-rate 120),
having a bulk density of 526 kg/m
3, and a dissolution time (T90) of 34 seconds.
Example 10 - Neutralisation of LAS acid in high shear mixer
[0119] This is modification of Example 9 using still more LAS acid and a different mixer.
1.0 kg of HMC 3 was charged to a Zanchetta RotoJunior (10 litre) high shear granulator/mixer,
and mixed using an agitator speed of 350 rpm and a chopper speed of 1350 rpm. Whilst
the powder was mixing 0.45 kg of LAS acid was added at a constant rate over a period
of 4 minutes using a peristaltic pump. On completion of the addition of the LAS acid,
mixing was continued for a further 30 seconds, after which time, the solid product
was discharged from the mixer.
[0120] The granulated product was a readily soluble, free-flowing powder (flow-rate 110),
having a bulk density of 557 kg/m
3, and a dissolution time (T90) of 33 seconds.
Example 11 - Neutralisation of LAS acid in high shear mixer
[0121] This is a repeat of Example 10 with even more LAS acid. 1.0 kg of HMC 3 was charged
to a Zanchetta RotoJunior (10 litre) high shear granulator/mixer, and mixed using
an agitator speed of 350 rpm and a chopper speed of 1350 rpm. Whilst the powder was
mixing 0.721 kg of LAS acid was added at a constant rate over a period of 4 minutes
using a peristaltic pump. On completion of the addition of the LAS acid, mixing was
continued for a further 30 seconds, after which time, the solid product was discharged
from the mixer.
[0122] The granulated product was a readily soluble, free-flowing powder (flow-rate 142),
having a bulk density of 655 kg/m
3, and a dissolution time (T90) of 42 seconds.
Comparative Example A - Neutralisation of LAS acid with Sodium Carbonate in Fukae
[0123] This is a comparative example that substitutes the HMC neutralisation process according
to Example 1 with an analogous process using unmodified Sodium Carbonate. 4.0 kg of
commercial light soda ash (ex Brunner Mond) with mean particle size of 110 micron
(Reference Carbonate B) were charged to a Fukae FS30 high shear granulator/mixer,
and mixed using an agitator speed of 200 rpm and a chopper speed of 1300 rpm. Whilst
the powder was being mixed, 1.032 kg of LAS acid was added at a constant rate over
a period of 4 minutes using a peristaltic pump. On completion of the addition of the
LAS acid, mixing was continued for a further 30 seconds, after which time, the product
was discharged from the mixer.
[0124] This over granulated product had very poor flow properties, having the appearance
of wet sand, and was not suitable for use as detergent granules. Even use of lower
amounts of surfactant acid did not give satisfactory granules using this process.
Examples 12 to 16 and B - Dry neutralisation of LAS acid using various carbonate materials
Example 12
[0125] 30 g of HMC 1 was placed in a laboratory scale granulator (Braun MR 500 CA) and reacted
with LAS acid, which was added manually to the granulator, via a syringe, through
a small hole drilled in the top of the granulator's lid until the onset of granulation.
The weight of LAS acid added at that point was 18 g. Further LAS acid was then added
until the granules started to stick together as dough (over-granulation). The maximum
amount of LAS acid that could be added to form detergent granules was 29.5 g.
Example 13
[0126] 20 g of HMC 3 was placed in a laboratory scale granulator (Braun MR 500 CA) and reacted
with LAS acid, which was added manually to the granulator, via a syringe, through
a small hole drilled in the top of the granulator's lid until the onset of granulation.
The weight of LAS acid added at that point was 15 g. Further LAS acid was then added
until the granules started to stick together as dough. The maximum amount of LAS acid
that could be added to form detergent granules (before over-granulation) was 31.5
g.
Example 14
[0127] 30 g of HMC 4 was placed in a laboratory scale granulator (Braun MR 500 CA) and reacted
with LAS acid, which was added manually to the granulator, via a syringe, through
a small hole drilled in the top of the granulator's lid until the onset of granulation.
The weight of LAS acid added at that point was 13 g. Further LAS acid was then added
until the granules started to stick together as dough. The maximum amount of LAS acid
that could be added to form granules (before over-granulation) was 24.2 g.
Example 15
[0128] 20 g of HMC 5 was placed in a laboratory scale granulator (Braun MR 500 CA) and reacted
with LAS acid, which was added manually to the granulator, via a syringe, through
a small hole drilled in the top of the granulator's lid until the onset of granulation.
The weight of LAS acid added at that point was 13 g. Further LAS acid was then added
until the granules started to stick together as dough. The maximum amount of LAS acid
that could be added to form granules (before over-granulation) was 24.4 g.
Example 16
[0129] This example was a repeat of Example 12 with 30 g of HMC 6 replacing the 30 g of
HMC 1.
[0130] The amount of LAS acid that could be added to the point of "maximum granulation"
(i.e.: maximum amount of LAS acid before over-granulation occurs) was determined to
be 37.0 g
Comparative Example B
[0131] 40 g of commercial anhydrous Sodium Carbonate (Light Ash ex Brunner Mond) (Reference
Carbonate B) was placed in a laboratory scale granulator (Braun MR 500 CA) and reacted
with LAS acid which was added manually to the granulator, via a syringe, through a
small hole drilled in the top of the granulator's lid until the onset of granulation.
The weight of LAS acid added at that point was 9 g. Even at this low level of addition
of LAS acid, the granules were of poor quality in terms of flow and stickiness. Addition
of further LAS acid caused the granules started to form an even stickier mass.
Examples 17-22 showing granulation over a range of LAS/Carbonate ratios.
[0132] One of the advantages of the inventive process is the ability to granulate successfully
over a wide range of HLAS carbonate ratios. This series of examples were prepared
to demonstrate this benefit. The method and materials are the same as for Example
4.
[0133] The amount of LAS acid added, and key physical properties of the resulting detergent
granules (BD - bulk density, DFR - Dynamic flow rate, d - Mean particle size, and
T90 - dissolution rate) are shown in Table 2. All samples have good granulometry,
flow-rate and dissolution properties.
Table 2
Example |
17 |
18 |
19 |
20 |
21 |
22 |
LAS acid/HMC w/w |
356g/kg |
406g/kg |
449g/kg |
502g/kg |
544g/kg |
624g/kg |
BD (kg/m3) |
594.45 |
592.425 |
619.65 |
635.625 |
663.75 |
743.625 |
DFR (ml/s) |
98 |
118 |
120 |
125 |
87 |
85 |
D (micron) |
365 |
331 |
362 |
392 |
311 |
460 |
T90 (s) |
41.7 |
37.7 |
42 |
44 |
48.5 |
57.5 |
Comparative Example C: Preparation of Detergent Granules using Burkeite (Reference
Carbonate C)
[0134] 1.5 kg of the spray-dried Reference Carbonate C were charged to a Zanchetta RotoJunior
(10 litre) high shear granulator/ mixer, and mixed using an agitator speed of 350
rpm and a chopper speed of 1350 rpm. Whilst the powder was mixing 0.15 kg of LAS acid
was added at a constant rate over a period of 2.5 minutes. On completion of the addition
of the LAS acid, mixing was continued for a further 30 seconds, after which time,
the solid product was discharged from the mixer. The granulated product was a free-flowing
powder (flow-rate 115), having a bulk density of 715 kg/m
3.
Comparative Example D: Preparation of Detergent Granules using milled ash.
[0135] 1.5kg of Sodium Carbonate (light ash ex Brunner Mond) that had previously been milled
to a mean particle size of 50 micron (Reference Carbonate D) were charged to a Zanchetta
RotoJunior (10 litre) high shear granulator/mixer, and mixed using an agitator speed
of 350 rpm and a chopper speed of 1350 rpm. Whilst the powder was mixing 0.364 kg
of LAS acid was added at a constant rate over a period of 5.75 minutes. The amount
added was just sufficient to prevent over-granulation. On completion of the addition
of the LAS acid, mixing was continued for a further 30 seconds, after which time,
the solid product was discharged from the mixer.
The granulated product was a free-flowing powder (flow-rate 90), having a bulk density
of 705 kg/m
3.
Examples 23 and 24 - Perfume loading of detergent granules
Example 23
[0136] 200 g of the detergent granules from Example 2 was sprayed in a laboratory scale
rotating pan with 6.0 g of perfume oil. The flow rate of the resultant powder was
measured as 137 g/min.
Example 24
[0137] 200 g of the detergent powder from Example 2 was sprayed in a laboratory scale rotating
pan with 10.0 g of perfume oil. The flow rate of the resultant powder was measured
as 140 g/min.
Example 25 - Neutralisation of LAS acid in high shear mixer (no chopping action)
[0138] 1.0 kg of HMC 1 were charged to a Zanchetta RotoJunior (10 litre) high shear granulator/mixer,
and mixed using an agitator speed of 350 rpm but with the choppers switched off. Whilst
the powder was mixing 0.353 kg of LAS acid was added at a constant rate over a period
of 4 minutes using a peristaltic pump. On completion of the addition of the LAS acid,
mixing was continued for a further 30 seconds, after which time, the solid product
was discharged from the mixer.
[0139] The granulated product was a readily soluble, free-flowing powder (flow-rate 146),
having a bulk density of 549 kg/m
3, and a UCT value of 2.5 kg - this means it would cake easily, for example in silo-storage.
Thus, this variant of the process is less preferred due to the lower loading of the
anionic surfactant achievable and the caking problem indicated by the high UCT result.
[0140] Note that this example is essentially a repeat of Example 4 (which has the choppers/cutters
operating) and achieves a higher surfactant content, similar DFR and same bulk density
but has been measured to have a UCT of zero and would therefore not have a caking
problem.
Example 26 and Comparative Example E - Storage stability
[0141] 398 g of the detergent granules of Example 2 was stored in an open, plain cardboard
carton (dimensions 15.4 cm wide, 7.0 cm deep and 13.0 cm high) at a temperature of
28°C and relative humidity of 70%RH for a period of 6 weeks. On removal from storage,
these detergent granules had not caked and were still free-flowing (flow rate-133).
[0142] For comparison, 388 g of the product of Comparative Example A was stored in the same
type of cardboard carton under the same conditions for a period of less than 6 weeks.
On removal from storage, this powder was heavily caked, in large lumps and did not
flow freely from the carton.
[0143] The granules according to the invention made using habit modified Sodium Carbonate
in the dry neutralisation process are non-caking at higher surfactant levels than
those made with conventional Sodium Carbonate in the dry neutralisation process.