Note: Descriptions are shown in the official language in which they were submitted.
- 1 - 2~2~3~
POLYMER-CONTAINING GRANULATES
This invention is concerned with polymer-containing granules useful
as a component for detergent formulations. In the following, "detergent
formulations" is intended to encompass deaning agents for both fabrics and
hard surfaces.
For environmental reasons it has become desirable to reduce or
eliminate the phosphate content of detergent formulations. Consequently a
replacement component which would provide similar properties, such as
inhibition of salt and soil redeposition on washed fabric, and hard surfaces
and improved whiteness, must be added. Polymeric additives, especially
polycarboxylated polymers, are suitable for this purpose.
Polymers are generally added to detergent formulations either in the
form of a dry powder, formed by spray-drying a solution, dispersion, slurry or
emulsion of polymer in a liquid ('wet polymer'), or directly as wet polymer to
a detergent formulation in slurry form before drying. In both cases, the final
product has a number of undesirable features.
The dry powder formed by spray-drying wet polymer alone is a
material which is hygroscopic and therefore tends to become 'sticky' upon
storage or in the final formulation itself. Such dry polymer also has a low
bulk density, typically 300-500 g/l, which means that in a typical detergent
formulation having density in the region of 700 g/l the polymer has a
tendency to separate out; it also reduces the bulk density of the formulation.
Furthermore, the dry polymer powder usually has a high proportion of fine
material, leading to undesirable dusting problems in the final formulation,
and further contributing to the problem of separation.
One method of adding wet polymer is to add it to other components of
the final formulation before drying, and then to spray-dry the polymer and
other components together. An example of a granulate composition made by
such a method is clisclosed in DE-A-3316513, in which a granule for use as a
phosphate substitute, containing 30-75% zeolite together with at least 5%
- 2 - 2 ~ 3 ~
polycarboxylate, is made by spray-drying a slurry of the components. Such a
spray-clrying process invariably yields a granulated product of undesirably low
density, and indeed the highest density achieved by this composition is 610
g/l; also, additional water - that introduced with the polymer - has to be
removed.
An alternative method for adding wet polymer is to add it directly to
the final formulation as it is mixed and dried in a rotating drum mixer.
However wet polyrner contains liquid (usually water) and polymer in a ratio
of about 1:1, so that adding more than 3ust a few percent of polymer requires
the addition of a significant amount of liquid also: solubilization by the
liquid of other components in the formulation tends to result in the
formulat~on of a paste in the dryer. This problem cannot be avoided by
reducing the liquid content of the polymer prior to addition, because the
viscosity of the wet polymer becomes too high for satisfactory flowability
and even distribution of the polymer amongst the other components.
The above method of adding wet polymer rnay be used when polymers
are to be employed as agglomerating agents for salts; in such a case they are
added at concentrations of only about 0.5%, so that the difficulties with excessliquid become insignificant.
The above problems also cannot be avoided by adding the polymer to
solutions of other salts to be used in the final formulation such as sulphates
and carbonates, and then drying by evaporation, because the polymers used
are effective crystallization inhibitors for those salts.
In summary therefore, forms of dry polymer hitherto produced have
proved unsatisfactory for detergent formulations in that (i) the polymer dried
alone has particle size, hygroscopicity and density disadvantages and (ii) the
polymer dried in the presence of the rernainder of the formulation induces
paste formation if dried in spray-mixing equipment or reduces to too low a
density if dried in a spray tower. There was no indication, indeed the
experience in (ii) contraindicated, that the polymer could be successfully
combined with some of the other components for the detergent formulation
into a granular forrn, having desirable particle size and bulk density, for
~2~i
- 3 -
addition to the detergent formulation.
A high density polymer-containing granulate is known, from
EP-A-368137; it contains 60-80% zeolite, 2-15% polycarboxylate, and 1~-25% by
weight of water, and has a density of 750-1000 g/l. However, the presence of
such a large proportion of water-insoluble zeolite brings disadvantages.
Water-insoluble salts have a tendency to deposit on fabrics, a problem which
the addition of polymers is at least partly intended to co~interact; in a granule
containing such a high ratio of water-insoluble salt to polymer, any effect as asuspending agent which the polymer Inight have been intended to have
would be virtually nullified by the large amount of zeolite introduced with
the polymer.
A granular detergent additive is known from US-A-4698174 which
comprises 20-80% polymer, 20-80% nitrilotriacetic acid (NTA) and optionally
up to 20% of another additive such as sodium sulphate. Densities of up to 690
g/l are disclosed, and the product is also said to have low hygroscopicity.
However, the usefulness of this additive is limited by the necessity for it to
comprise a significant proportion of NTA to obtain satisfactory performance;
large proportions of NTA may be considered undesirable on environmental
grounds. Furthermore the densities disclosed are still generally less than the
average density of a typical detergent.
In a first aspect the present invention provides a composition, useful as
a component of a detergent formulation, in the form of granules each
comprising at least 10% by weight of polymer useful in such formulations
and at least 20% by weight of at least one water-soluble inorganic component
also useful in such formulations, the bulk density of said composition being
at least 700 g/l. Preferred inorganic components are salts, such as sulphates,
carbonates and silicates. Perborates (both mono- and tetrahydrate),
percarbonates and persulphates may also be useful. In formulations where
phosphates are still present, they may also be used as carriers. For all the
above salts, the sodium form is preferred.
The present invention is also applicable to the case where the inorganic
component is zeolite or clay, which are both water-insoluble. In such a case, a
~2 ~ 2
- 4 -
greater proportion of polymer is necessary in order to counteract the tendency
of the water-insoluble component to deposit on fabrics, as indicated above.
Accordingly in a second aspect the present invention provides a composition,
useful as a component in detergent forrnulations, in the form of granules
each comprising at least 20% by weight of polymer useful in such
formulations and at least 20% by weight of zeolite, the bulk of density of said
composition being at least 700 g/l.
It will be appreciated that in both cases the granules may contain minor
amounts of other components which are suitable for use in detergent
compositions.
The density of the granulate may be as low as 300 g/l or as high as 1400
g/l, although a density in the range from 700 to 1200 g/l is preferred,
particularly over 900 g/l. The density depends on the type of inorganic
component ("carrier"), on polymer type, and on manufacturing process
conditions and equipment (discussed hereinafter), and also on the relative
proportions of polymerts) and carrier(s). Thus granules containing up to 80%
polymer by weight may be prepared. In this case, the density of such granules
will be at the bottom end of the desired range. Typically 10% to 50% by weight
polymer is present in the granule (but at least 20%, preferably at least 25%
where zeolite is present), and more typically from 20% to 40%. The most
preferred amount of polymer is 30%.
Suitable polymers include homopolymers or copolymers of
dicarboxylic acids such as maleic acid, itaconic acid, mesaconic acid, fumaric
acid, citraconic acid and the anhydrides of cis dicarboxylic acids, such as maleic
anhydride; monocarboxylic acids such as acrylic acid, methacrylic acid, vinyl
acetic acid, crotonic acid and acryloxypropionic acid; and unsaturated
non-carboxylic acids such as alkyl esters of acrylic or methacrylic acids such as
methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl
methacrylate, butyl methacrylate and isobutyl methacrylate; hydroxyalkyl
esters of acrylic or methacrylic acids such as hydroxyethyl acrylate,
hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl
methacrylate (including polyethoxylated esters); acrylamide, methacrylamide,
- 5 - 2 ~ 9
N-tertiary butyl acrylamide, N-methyl acrylamide, N,N-dimethyl acrylamide;
acrylonitrile, methacrylonitrile, allyl alcohol, allyl sulfonic acid, allyl
phosphonic acid, vinylphosphonic acid, dimethylaminoethyl acrylate,
dimethylaminoethyl methacrylate, phosphoethyl methacrylate, N-vinyl
pyrrolidone, N-vinylformamide, N-vinylimidazole, ethylene glycol
diacrylate, trimethylolpropane triacrylate, diallyl phthalate, vinyl acetate,
styrene, vinyl sulfonic acid and its salts, and 2-acrylamido-2-methyl propane
sulfonic acid (AMPS) and its salts. Monomers of 1-olefins, such as
diisobutylene and 1-octene, are also suitable, as is the polyrner "POC" (the
reaction product of acrylic acid and peroxodisulphate).
Polymers can be in acid or neutralized or partially neutralized form
with Na, K, NH4 or other counterions. Molecular weights of the polymers
may be from 500 to 5,000,000. Generally the higher molecular weight, the
greater the degree of agglomeration obtained during manufacture of the
granules and hence the larger the granules. Thus the choice of molecular
we;ght will be at least partly dependent on the granulometry of the product
required.
Examples of polymers employed in the present invention are an acrylic
acid homo-polymer having a weight-average molecular weight of 4500 and
an acrylic/maleic copolymer having a weight-average molecular weight of
about 70,000.
The granules of the present invention can have a wide range of size
distributions, from 1 micron to 2mm or more in diameter. Granulates with
up to 80-% particles on 14 U.S. mesh (mesh size 1.18 mm) or with up to 80%
particles through 100 U.S. mesh (mesh size 0.15 mm) can be produced. It is
preferred that less than 50% by weight pass through 100 U.S. mesh. In a
preferred option, the size of the granules formed is such that it approximates
to the average size of particles in a standard detergent composition (0.2-
0.4mm typically).
The granular composition of the invention provides polymer suitable
for use in detergent formulations in a form which has considerable
advantages over the prior art. The dry granule may be added direct to the
2 0 2 ~ ~ r /
- 6 -
final formulation, thereby cirCumventing all the disadvantages associated
with wet polymer. The composition can be adjusted to have a granulometry
and density very similar to that of the other components in the final
formulation, thereby avoiding the problerns of separation and dusting
associated with spray-dried polymer. Furthermore, the granular composition
of the present invention does not suffer from the problems of hygroscopicity
which affects spray-dried polymer. The larger particulate size means that
there is less surface area per unit weight to absorb moisture, and also the
proportion of hygroscopic polymer in each granule is obviously less than in
'dry polymer' powder. For the purposes of the present invention, a granulate
which absorbs less than 20% of its own weight in water when exposed to
moisture is preferred, particularly less than 10%. The method employed to
determine this percentage of water absorption is as follows:
A previously weighed container is placed in an air-conditioned room
at a temperature of 20C and humidity of 50%, filled with a thin layer
(5-20mm) of polymer and immediately reweighed, at which point the test
starts. The container and polymer are then reweighed at ten minute intervals
during the first hour, 30 minute intervals during the second hour, hourly
during the next five hours and then every 24 hours. The percentage increase
in weight gives the amount of water absorbed, and the figure quoted is that
attained when a steady state has been reached.
Thus the present invention has successfully solved the problem of
obtaining polymer in a form which is acceptable for direct addition to
detergent formulations, without the attendant problems either of the liquid
carrier associated with the polymer, or of the consequences of having
removed that liquid carrier first. Furthermore, the present invention
provides a much more flexible solution to the previous problems than
known compositions such as those described hereinabove, in that there is a
wide variety of inorganic components which can be incorporated with the
polymer, with no individual compound being an essential prerequisite.
Additionally, the density of the composition of the invention can be
significantly higher than that possible with known compositions.
- 7 -
The present invention also provides, in further aspect, a detergent
formulation containing polymer in the form of a composition as defined
above; and in a still further aspect it comprises the use of a composition as
defined above as a cormponent in a detergent formulation. The proportion of
the granulate composition of this invention re~uired in a typical detergent
formulation will generally be such as to give an active polymer con-tent in the
formulation of from 0.1 to 20% by weight, more usually between 1 and 5%.
Typical detergents for which the granular composition of the present
invention may be suitable are usually based on surfactants and, optionally, on
either precipitant or sequestrant builders. Suitable surfactants are, for
example, anionic surfactants, such as (C~ to Cl2) alkylbenzenesulfonates, (Cl2
to Cl63 alkane sulfonates, (Cl2 to Cl6) alkylsulfates, (Cl2 to Cl6)
alkylsulfosuccinates and (Cl2 to Cl6) sulfated ethoxylated alkanols. Nonionic
surfactants may be (C6 to Cl2) alkylphenol ethoxylates, (Cl2 to C20) alkanol
alko~ylates, and block copolymers of ethylene oxide and propylene oxide.
Optionally, the end groups of polyalkylene oxides can be blocked. This means
the free OH groups of the polyalkylene oxides can be etherified, esterified,
acetalised and/or aminated. Another modification consists of reacting the
free -OH groups of the polyalkylene oxides with isocyanates.
Nonionic surfactants may also include (C4 to Cl8) alkyl glucosides as
well as the alkoxylated products obtainable therefrom by alkoxylation,
particularly those obtainable by reaction of alkyl glucosides with ethylene
oxide. Surfactants useful in detergents can also have an amphoteric character
and they can be soaps. In general, the surfactants constitute from 2 to 50 wt %
of a detergent.
Sequestrant builders contained in detergents have generally been
phosphates, orthophosphates, pyrophosphates or especially sodium
tripolyphosphate. However, because of the severe environmental pollution
caused by the use of phosphates, the phosphate content of detergents and
cleaning agents is increasingly being reduced so that detergents currently
contain up to 25% of phosphates or preferably are phosphat~free. ~s
discussed previously, the composition of the present invention is primarily
2 ~ 2 ~ ~ ~
- 8 -
of value as a means for introducing into the detergent a partial or complete
replacement for phosphates, comprising polymers as previously listed. Other
builders include zeolites, sodium carbonate, nitrilotriacetic acid, citric acid,tartaric acid, the salts of the aforesaid acids and the monomeric, oligomeric orpolymeric phosphonates. Varying amounts of the individual substances are
used in the preparation of detergent formulations. For example, sodium
carbonate may be used in an amount of up to 80%, phosphates up to 80%,
zeolites up to 40%, nitrilotriacetic acid and phosphonates up to 10% and
polycarboxylic acids in an amount of up to 30% by weight based on the total
detergent formulation.
Typical detergent formulations optionally also contain corrosion
inhibitors, such as silicates as additional additives. Suitable silicates are, for
example, sodium silicate, sodium disilicate and sodium metasilicate. The
corrosion inhibitors can constitute up to 50 wt % of the detergent
formulation. Other common additives to detergent and cleaning agent
formulations are bleaching agents used in an amount of up to 30 wt %.
Suitable bleaching agents are for example, perborates, percarbonates, or
chlorine-generating substances, such as chloroisocyanurates. Another group
of additives that can be used in detergents are greying inhibitors. Known
substances of this type are carboxymethylcellulose, methylcellulose,
hydroxypropylmethylcellulose and graft copolymers of vinyl acetate and
polyalkylene oxides having a molecular weight of 1000 to 15,000. Greying
inhibitors are used in the detergent formulations in an amount of up to 5%.
Other common detergent additives that can optionally be used are optical
brighteners, enzymes and perfume. Powdered detergent formulations can
also contain up to 50 wt % of a diluent, such as sodium sulfate. The detergent
formulations can be anhydrous or they can obtain small amounts, for
example up to 10 wt %, of water.
The composition of the present invention may be made by a process
according to a further aspect of the invention, which comprises mixing
polymer useful in detergent compositions with a liquid suitable for carrying
or solubilizing said polymer and at least one solid inorganic component, the
9 2~2~J3~
ratio of polymer to inorganic component being from 1:9 to 5:1, and subjecting
the mixture to conditions of agitation and heat such that granules are ~ormed.
Generally the polymer and liquid are introduced together - as a slurry,
solution, emulsion, suspension or dispersion of polymer in liquid. Preferably
the granules formed are as defined hereinabove.
The particular conditions of heat and agitation which are required in
order to produce the desired granules are complex, and dependent on a large
nu nber of interrelated variables. It is highly important that the polymer,
liquid and inorganic component are subjected to a degree of turbulence such
that rapid and intimate mixing, plus uniform heating is achieved;
additionally a rapid and effective rate of heat transfer is required in order toevaporate the liquid very soon after the mixture is formed, especially when
the inorganic component is soluble in the liquid.
In a preferred embodiment of the process which achieves the above
requirements, the components are mixed in a horizontal cylindrical chamber
having an axial shaft which carries a series of radial blades extending almost
to the wall of the chamber, which forces the mixture into a highly turbulent
thin layer around the wall of the chamber. A pressure differential moves the
mixture along the chamber, where it is additionally subjected to heating by
one or both of hot air blown through the chamber and heating of the chamber
wall in contact with the mi~ture layer. The mixture may be subjected to
heating as soon as it enters the chamber; alternatively, heat may be applied
after the mixture has passed a little way along the chamber, so that initial
mixing occurs before the commencement of evaporation. This alternative
procedure may also be embodied by employing two chambers, in series, the
first of which subjects the mixture solely to high agitation and the second of
which subjects it both to agitation and to heating. This method allows greater
control of the degree of turbulence at each stage, although, for reasons
outlined above, care may be needed in determining the residence time in the
initial mixing chamber to ensure that evaporation does not commence too
late.
Although the chamber~s) is preferably horizontal, this is not essential
2~3 ~
- 1n -
and it may be inclined or even vertical.
The unique combination of turbulence and rate of heat transfer
provided by the process of this invention results in a product which was not
previously achievable. The granules produced are generally an
agglomeration of many particles, each particle comprising a core of inorganic
component ('carrier') coated with a layer of polymer, although under certain
conditions a homogeneous mixture may be formed. The process of the
invention is particularly advantageous in the case where the inorganic
component is soluble in the liquid (usually water) carrying the polymer. An
example is where the inorganic component is a sulphate, which is soluble in
water. In such a case, the evaporation of the liquid in this process is so rapidthat solubilization of the inorganic carrier occurs only to an extent which is
insufficient to deleteriously affect the density or particle size of the final
granulate product. This would be impossible with conventional techniques.
As mentioned above, the parameters influencing the nature of the
final product are many and complex. The relative proportions of polymer
and carrier are significant; increasing the proportion of polymer reduces the
density of the final granules, and also results in larger granules by causing
more agglomeration. The nature of the components is also significant. As
discussed previously, the molecular weight of the polymer can influence the
granulometry of the final product. It can be advantageous for the inorganic
component to be an anhydrous salt, since this will absorb water carrying the
polymer during mixing, thereby leaving less to be evaporated and speeding
the process. The two main process conditions which need to be influenced
are the rate of heat transfer to the components as they are being mixed, and
the degree of turbulence of that mixing. As a generalisation, increasing either
the rate of heat transfer or the turbulence reduces the degree of
agglomeration, and hence the size of the particles.
The rate of heat transfer may be enhanced by increasing either the
temperature or the flowrate of the hot air which is passed through the
chamber, or by increasing the temperature of the heating jacket around the
wall of the chamber. As discussed previously, the positions of the hot air
- -,1 2 (3 ~, 3 ~J ~
inl( t and tl~e heatirlg jacket may also be adjus~ed to influence the tirning and
ral~ of heat ~ranxfer. rhe initial temperature of the liquid carrying the
polymer may also be varied; increasing this not only improves the
evaporation capaci~y of the apparatus, but also the homogeneity of the final
granule by reducing the initial viscosity of the liquid/polymer system. The
rate of heat transfer is also increased by greater turbulence.
The turbulence of the rnixture in the chamber nnay be increased by
increasing the speed of rotation of the shaft and blades. It is also influenced by
the na~ure of the blades - their number, shape, orientation, etc; it will be
appreciated that the precise effect of the blades is a matter for assessment in
eacll case.
Another factor of significance is the residence time of the mixture in
the chamber - i.e. the length of time of its exposure to heating and/or
turbLIlc~llt mixing, which has to be adjusted to provide the optimum balance.
Tlle mixture is drawll throug}l the chamber largely by a pressure differential,
varialion of which will of course alter the residence time. The length of the
chamber - or separation into a mixing and a mixing/heating chamber - is
another influencing factor.
l'referred embodiments of both the process and the composition of the
invention will now be described with reference to the accornpanying
drawings, in which:
Figure 1 is a diagranlmatic representation of an agglomerating
apparatus suitable for performing a preferred plocess of the invention;
I igures 2 to 4 are graplls shvwing the granulometry of compositions of
the invention.
Referring to I igure 1, preferred apparatus for the agglomeration process
of the inventic)ll comprises a horizontal cylindrical chamber 2 having at one
end inlets 4,6 lor the liquid/polymer system and dry inorganic carrier
respectively, alld at its other end an outlet 8 for the granulated product. An
air compressor 22 pushes the air (and llence the material) along the chamber,
and a fan 10 contributes to a pressure drop which also helps to draw the
material through.
- 12 - ~ 0 ~ 3 2
Heating is accomplished partly by hot air injected into the chamber
through inlet 12, and partly by a coaxial heating jacket 1~ around the
chamber. Hot air inlet 12 and jacket 14 are spaced along the chamber from the
raw material inlets 4,6 so that materi~l in the initial portion of the chamber is
not subjected to heating, but only to mixing. As discussed previously, in an
alternative embodiment this initial mixing without heating phase (which is
not always essential) may be performed in a separate charnber.
Turbulent mixing is accomplished by means of a rapidly rotating axial
shaft 16 which carries a series of blades 18 each extending radially towards thewall of the chamber. In this embodiment each blade is substantially
rectangular, and its outer edge is spaced from the internal wall of the chamber
2 by a few millimetres (this spacing being adjustable). Shaft 16 is driven by a
motor 20. In certain embodiments movement of the material along the
chamber may be accomplished solely by the rotating blades, without the need
for a pressure differential.
The operation of the apparatus of Figure 1 is as follows, described with
reference to a preferred composition comprising a polymer/water system.
Dry carrier and a solution of polymer in water enter the chamber 2
through respective inlets 4,6. The polymer solution may already be at
elevated temperature in order to reduce its viscosity and improve mixing.
Inside the charnber the shaft 16 and its blades 18 are rotated at a high rate,
typically from 500 to 3000 rpm. The rate employed depends of course on
factors such as the diameter of the drum, since the important parameter is the
tangential velocity imparted to the mixture at the surface of the chamber wall
(in this particular embodiment the tangential velocity is generally from 10 to
30 ms~
The mixture of polymer, water and carrier is drawn through the
chamber by the combined action of compressor 22 and fan 10, whilst the
centrifugal force created by the rapdily rotating blades 18 forces the mixture
into a highly dynamic suspension in the form of a thin layer around the
internal surface of the chamber wall. The precise thickness of the layer
depends on a number of factors, particularly the degree of centrifugal force
202~
- 13 -
exerted on it, but it is app~oximately 1-2 nun. The blades are preferably
arranged to extend close enough to the chamber wall that their outer edges
contact and disrupt the layer of agglomerating mixture, thereby generating
further turbulence and inhibiting the development of excessively large
granules.
The residence time of the mixture in the initial unheated portion of
the chamber is very short - of the order of a few seconds. It is especially
important if the carrier is soluble in water that the carrier does not begin to
dissolve before evaporation of the water begins. Of course, if necessary the
apparatus may be arranged so that the mixture is subjected to heating as soon
as it enters the mixing chamber.
After this initial mixing phase, the mixture is subjected to heating by
hot air injected through inlet 12 and saturated steam passing around jacket 14.
Together these provide a very efficient combination of both convective and
conductive heat transfer, resulting in rapid evaporation of the water from the
mixture. The continuous rotation of the mixture layer and individual
particles within it provides ideal conditions of turbulence and particle
separation, permitting uniform heating and excellent agglomeration.
The mixture reaches outlet 8 after a time period of from around 10
seconds to a few minutes, by which time it has agglomerated into dense, dry
granules of polymer and carrier, with the water being removed as vapour.
Specific examples of granulated compositions of the present invention
produced by the above exemplified process are as follows:
Example 1:
A granulate containing 30% dry polymer is obtained as follows: 100
kg/h of sodium sulphate and 95 kg/h of a 45% water solution of an acrylic
acid homopolymer having a weight average molecular weight of 4500 are fed
continuously into the mixer chamber.
The shaft speed rotation is 900 rpm, the hot air is fed (co-currently with
the granule flow) into the mixing chamber at 225C and 280 m3/h. Saturated
steam at 160C is fed into the jacket.
'; 3 ~
- 14 -
Finished product ~granulates) is discharged continuously starting about
one minute after the operation start-up, at 143 kg/h, 0,5% residual moisture
and 100C. The density of the product is 1000 g/lt and the granulometry
spectrum, compared with leading fabric-wash detergents, is shown in Figure
2.
Exam~le 2:
A product containing 10% dry polymer is obtained by employing the
same process conditions as Example 1, but with 100 kg/h of sodium sulphate
and 28 kg/h of an acrylic/maleic copolymer having a weight average
molecular weight of 70,000.
Density of the granulates is 1200 g/lt, and the granulometry
distribution is shown in Figure 3.
Examp~:
~ product containing 30% dry polymer is obtained as follows: 120 kg/h
of sodium carbonate and 115 kg/h of the polymer of Example 1 are fed
continuously into the mixing chamber. The shaft speed rotation is 1800 rpm,
the hot air is fed c~currently at 200C. Saturated steam at 180C is fed into the
jacket. Finished product is obtained at 1% residual moisture at 70C. The
density of the product is 860 g/lt and the granulometry spectrum is shown in
Figure 4.
