Note: Descriptions are shown in the official language in which they were submitted.
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Process for the solvent-free continuous pre~aratior~ of a material
prepared from pol mers and from thermosets
The invention relates to a process for the solvent-free continuous
preparation of a polymeric composition comprising a polymer and a
thermoset, where the thermoset is prepared in the polymer matrix from its
corresponding starting components, by reaction in an extruder, intensive
kneader, intensive mixer, or static mixer, through intensive mixing and brief
reaction with introduction of heat and with subseguent isolation of the final
z o product by cooling.
Polymer blends (PBs) are mixtures of two or more polymers. or copolymers.
These are prepared in order to improve the properties of an underlying
polymer. PBs are divided into homologous (HPBs), miscible (MPBs),
immiscible, and compatible products, and also polymer alloys. HPBs are
mixtures which are composed of two chemically identical polymers which
differ only in their molecular weight distributions. The mixtures are always
homogeneous, and the mixture is thermodynamically stable. In contrast,
MPBs are mixtures of polymers of different chemical structure, these being
2 o nevertheless thermodynamically stable. This very unusual situation occurs,
for example, where the segments of the macromolecules to be mixed enter
into specifically attractive interactions with one another ~(e.g. hydrogen
bonds or dipole-dipole or ion-dipole interactions). The great majority of
chemically different polymers are incompatible from a very low degree of
polymerization upward, and their incompatibility continues to rise as chain
length grows, as can be demonstrated on the basis of
statistical/thermodynamic considerations and experimental ~ findings.
Decisive factors here relevant to the compatibility of the PBs are
particularly their composition and pretreatment. ~nce the mixing procedure
3 o has taken place, if the opportunity for chain-movement and time have been
sufficient to permit development of relatively large phase-separated
regions, this is mostly observable from clouding of the material. PBs which
are then generally termed compatible are those products which appear to
the naked eye as homogeneous and whose physical properties are
3 5 superior to those of the components of the mixture.
Improved compatibility of polymers A and B can be achieved through
modification of polymer A by grafting-on small proportions of polymer B, or
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through adding AB block copolymers. In this system, graft copolymers or
block copolymers form the boundary between A phases and B phases,
thus tying these to one another. In these cases the term polymer alloys is
used. Compatibility may also be brought about by adding caertain additives.
However, a maximum of homogeneous miscibility is by no means always
desirable. For example, impact-modification of polymers such as
polystyrene, or the preparation of thermoplastic elastomers, would not be
conceivable without phase separation. PBs have a very important
economic role (R~mpp Lexikon Chemie [Rompp's Chemical Encycfopedia~
z o - Version 2.0, Stuttgart/New York: Georg Thieme Verlag 1999).
Polyester surface-coating resins often bear hydroxy groups> as a functional
group. Both liquid and solid products are used. A main application sector
for these resins is the production of surface coatings and coating materials,
which are likewise either liquid (e.g. coil coatings) or solid (powder
coatings). Using appropriate hardeners which can react with the OH groups
(e.g. polyisocyanates), the polyester resins are generallly cured at an
elevated temperature after application to a substrate, to give a long-lasting
and robust film of coating.
Thermosets are plastics which are produced byr irreversible and close-knit
crosslinking via covalent bonds starting from oligomers (technically:
prepolymers), or less often from monomers or polymers. The word
"thermosets" here is applied both to the raw materials prior to crosslinking
(see reactive resins) and is also used as a collective term for the cured
resins, which are mostly completely amorphous. At low temperatures,
thermosets are energy-elastic, and even at relatively high temperatures
they cannot undergo viscous flow, but behave elastically with very limited
deformability (R~mpp Lexikon Chemie [Rompp's Chemical Encyclopedia]
3 o Version 2.0, StuttgartlNew York: Georg Thieme Verlag 1999).
Now, one way of preparing a physical mixture of polymers, and specifically
of polyester resin and thermoset, would be to use a considerable amount of
mechanical energy to grind the cured thermoset and then to incorporate
3 5 the ground material into the liquid or molten polyester (e.g. with the aid
of a
mixer or extruder). Naturally, this does not achieve genuinely
homogeneous distribution of the thermoset in the polyester extending to
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the molecular range, since the maximum achievable fineness
of the ground material sets effective limits for
polyester/thermoset distribution.
Polymeric compositions of polymers and
thermosetting resins may be prepared batchwise in a mixer.
A disadvantage of this method of preparation is that the
polymers used (e. g. polyesters) continue to have relatively
high viscosities even at temperatures of from 180 to 220°C,
and these viscosities make it considerably more difficult to
incorporate the thermoset starting materials (e. g. polyamine
and polyisocyanate) rapidly and effectively. Since as the
amount of thermoset in the reaction mixture increases the
melt viscosity rises sharply, the use of a very powerful
mixer assembly is required, and the circumstances described
also severely limit the batch size for the batch process.
For the industrial preparation of these products, the method
is therefore very complicated and extremely inef:Eective.
zt has been therefore desired to find a novel
preparation process which is free of one or more
disadvantages of the prior art.
Surprisingly, it has now been found that a very
good distribution of the thermoset in polymers, and
specifically in polyesters, occurs if the thermoset is
prepared entirely within the polymer. F'or this, the
appropriate monomers, oligomers, and/or prepolymers are
reacted within the polymers in an extruder, an intensive
kneader, an intensive mixer, or a static mixer.
The invention provides a solvent-free continuous
process for preparing a polymeric composition of:
(A) at least one polymer, and
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(B) at least one thermoset in an amount of from
0.5 to 50o by weight based on the total of (A) and (B),
which process comprises:
producing the thermoset (B) by a reaction of:
(1) at least one starting component having NH2
groups, with
(2) at least one starting component having NCO
groups,
in a matrix of the polymer (A) in an extruder, an intensive
kneader, an intensive mixer or a static mixer by an
intensive mixing for a brief reaction time of no more than
minutes with an introduction of heat, wherein the
starting components (B1) and (B2) each have a functionality
of at least 2 and at least one of the starting components
15 (B1) and (B2) having a functionality of more than 2 is
present in an amount of from 0.5 to 100% by weight based on
the total of the components (B1) and (B2); and
subsequently isolating the polymeric composition
by cooling.
According to one preferred embodiment of the
process, the polymer (A) is a polymer having OH groups,
preferably a polyester and/or polyacrylate, having an OH
functionality of at least 2.
At thermoset contents of from 0.5 to 50% by
weight, preferably from 2 to 40% by weight, homogeneous
thermoset/polymer compositions are obtained which have
physical properties (such as melting point, glass transition
temperature Tg, melt viscosity) which differ from those of
the substances present separately after physical mixing. In
contrast, the chemical reactivity of the polymer which does
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not participate in the polymerization reaction is retained.
The resultant polymeric composition may then be further
processed like the underlying polymer.
Suitable polymers (A) are in principle any of
those which are known, e.g., thermoplastic resins, such as
polyolefins, polybutadienes, polystyrenes, polysiloxanes,
polyamides, as long as their melting point is not higher
than 220°C. Copolymers and block polymers are also suitable
as polymer (A), an example being styrene-dime polymers.
Suitable polymers whose functionality is at least
2 are generally any of the polymers which have
functionalities of this type' but in particular
polyacrylates and polyesters having hydroxy groups.
The polyesters whose use is preferred and which
contain hydroxy groups may be prepared by polycondensation of
suitable di- and/or polycarboxylic acids, or corresponding
esters and/or anhydrides, with di- and/or polyols. The
condensation takes place in a manner known per se, for
example, in an inert gas atmosphere at temperatures of from
100 to 260°C, preferably from 130 to 220°C, in the melt, or
by an azeotropic method, e.g. as described in Methoden der
Organischen Chemie [Methods of organic chemistry] (Houben-
Weyl); Volume 14/2, pp. 1-5, 21-23, 40-44, Georg Thieme
Verlag, Stuttgart, 1963, or in C.R. Martens, Alkyd Resins,
pp. 51-59, Reinhold Plastics Appl. Series, Reinhold
Publishing Comp., New York, 1961. The preferred carboxylic
acids for preparing polyesters may be aliphatic,
cycloaliphatic, aromatic, andjor heterocyclic in nature, and,
where appropriate, may have substitution by halogen atoms,
and/or may have unsaturation. Examples which may be
mentioned of these are: succinic, adipic, suberi~~, azelaic,
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sebacic, phthalic, terephthalic, isophthalic, trimellitic,
pyromellitic, tetrahydrophthalic, hexahydrophthalic,
hexahydroterephthalic, di- and tetrachlorophthalic,
endomethylenetetrahydrophthalic, glutaric, and
1,4-cyclohexanedicarboxylic acid and - where obtainable -
their anhydrides or esters. Particularly highly suitable
compounds are isophthalic acid, terephthalic acid,
hexahydroterephthalic acid, and 1,4-cyclohexanedicarboxylic
acid.
Examples of polyols which may be used are ethylene
glycol, propylene 1,2- or 1,3-glycol, butylene 1,4- or
2,3-glycol, di-~i-hydroxyethylbutanediol, 1,5-pentanediol,
1,6-hexanediol, 1,8-octanediol, decanediol, dodecanediol,
neopentyl glycol, cyclohexanediol, 3(4),8(9)-bis(hydroxy-
methyl) tricyclo [5.2.1. 02'6] decane- (Dicidol*) , bis (1, 4-
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hydroxymethyl)cyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane, 2,2-
bis[4-(~i-hydroxyethoxy)phenyl]propane, 2-methyl-1,3-propanediol, 2-
methyl-1,5-pentanediol, 2,2,4(2,4,4)-trimethyl-1,6-hexanediol, glycerol,
trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol,
tris([i-hydroxyethyl) isocyanurate, pentaerythritol, mannitol, sorbitol,
diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene
glycol, polypropylene glycols, polybutylene glycols, xylylene glycol, and/or
the neopentyl glycol ester of hydroxypivalic acid. Preference is given to
monoethylene glycol, neopentyl glycol, ~icidol; cyclohexanedimethanol,
trimethylolpropane, and glycerol.
Amorphous polyesters prepared in this way preferably have an OH value of
from 15 to 200 mg KOHIg, a Tg of from 35 to 85°C, a melting point from
60 to 110°C, and an acid value of <10 mg KOH/g. The molecular weights
are preferably from 2000 to 7000.
Crystalline polyesters prepared similarly have an OH value of from 15 to
130 mg KOH/g, a Tg of from -50 to 40°C, a rnelting poirrt from 60 to
130°C, and an acid value of c8 mg KOH/g. The molecular weights are
preferably from 1800 to 6500.
The acrylates whose use is preferred and which contain hydroxy groups
and have an OH value of from 20 to 150 mg/KOH, a molecular weight of
from 1800 to 6000, and a Tg of from 30 to 90°C are prepared by
polyaddition of suitable ethyienically unsaturated monomers. Examples of
these compounds are styrene, a,-methylstyrene, C2-C4o-alkyl acrylates or
C1-C4o-alkyl methacrylates, such as methyl methacrylate, ethyl acrylate,
propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl
acrylate, tart-butyl methacrylate, pentyl methacrylate, n-hexyl rnethacrylate,
3 0 n-heptyl methacrylate, n-octyl acrylate, 2-ethylhexyl acrylate, decyl
methacrylate, lauryl methacrylate, palmityl methacrylate, phenoxyethyl
methacrylate, phenyl methacrylate, cyclohexy! methacrylate, tert-
butyicyclohexyl acrylate, butylcyclohexyl methacrylate, and
trimethylcyclohexyl methacrylate. This group also includes hydroxyalkyl
esters of a,,[i-unsaturated carboxylic acids, e.g. of acrylic acid and/or
methacrylic acid, having a primary OH group and a C~-Ci8-hydroxyalkyl
radical, e.g. hydroxyhexyl acrylate, hydroxyoctyl acrylate, and the
corresponding methacrylates, and reaction products of hydroxyethyl
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(meth)acrylate with caproiactone, and also monomers having secondary
OH functions, for example adducts of glycidyl (meth)acrylate with saturated
short-chain acids having C,-C3-alkyl radicals, e.g. acetic acid or propionic
acid.
According to the invention, the thermoset B is prepared from its starting
components in the polymer matrix A. The starting components B1 and B2
have functionality of at least 2.0, and in component B there must always be
one starting o~omponent present whose functionality is greater than 2, in
amounts of from 0.5 to 100% by weight, based on component B. It is in
principle unimportant whether the amino component or the isocyanate
component has functionality of more than twos but it is preferable for the
isocyanate component to be used. The approximate molecular weight of
the thermosets vary from 2000 to 70 000, and are preferably greater than
4000.
In the composition, the amounts generally present of the thermosets B,
based on the polymeric composition, are from 0.5 to 50% by weight,
preferably from 2 to 30% by weight.
As component B2 for preparing the thermosets, use may be made of any of
the known aliphatic, cycloaliphatic, araliphatic, or aromatic isocyanates or
their isocyanurates, where obtainable, in pure form or in the form of any
desired mixtures with one another. Examples which may be listed are:
cyclohexane diisocyanates, methylcyclohexane diisocyanates,
ethylcyclohexane diisocyanates, propylcyclohexane diisocyanates, methyl-
diethylcyclohexane diisocyanates, phenylene diisocyanates, tolylene
diisocyanates, bis(isocyanatophenyl)methane, propane diisocyanates,
butane diisocyanates, pentane diisocyanates, hexane diisoc;yanates, such
3 0 as hexamethylene diisocyanate (HDI) or 1,5-diisocyanato-2-methyipentane
(MPDI), heptane diisocyanates, octane diisocyanates, nonane
diisocyanates, such as 1,6-diisocyanato-2,4,4-trimethylhexane or 1,6-
diisocyanato-2,2,4-trimethylhexane (TMDI}, nonane triisocyanates, such as
4-isocyanatomethyl-1,8-octane diisocyanate (TIN), decane di- or
3 5 triisocyanates, undecane di- or triisocyanates, dodecane di- or
triisocyanates, isophorone diisocyanate (IPDI}, bis(isocyanato-
methylcyclohexyl)methane (Hi2MDl), isocyanat~methyl methylcyclohexyl
isocyanates, 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane (NBDI),
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g
1,3-bis(isocyanatomethyl)cyclohexane (1,3-H6-XDI), or 1,4-
bis(isocyanatomethyl)cyclohexane (1,4-H6-XDI). The fist includes ali of the
regio- and stereoisomers of the isocyanates mentioned by way of example.
Preference is given to the use of HDI, IPDI, MPDI, TAIIDI, 1,3- and 1,4-Fi6-
XDI, NBDI, and mixtures of HDI and IPDI. Preferred polyureas for the
process of the invention are those composed of IPDI, IPDI isocyanurate,
HDI, or HDI isocyanurate, or of any desired mixture of these.
For the purposes of the invention, any of the aliphatic, (cyclo)aliphatic,
cycloaliphatic, or aromatic diamines and/or polyamines (C~-C,e) may be
used as component B1.
Suitable diamines are in principle 1,2-ethylenediamine, 1,2-
propylenediamine, 1,3-propylenediamine, 1,?-butylenediamine, 1,3-
butylenediamine, 1,4-butylenediamine, 2-(ethylamino)ethylamine, 3-
(methylamino)propylamine, 3-(cyclohexylamino)propylamine, 4,4'-
diaminodicyclohexylmethane, isophoronediamine (IPD), 4,7-dioxadecane-
1,10-diamine, N-(2-aminoethyl)-1,2-ethanediamine, N-(3-aminopropyl)-1,3-
propanediamine, N,N"-1,2-ethanediylbis(1,3-propanediamine), and also
2 0 hexamethyienediamines, which may also bear one or more C,-C4-alkyl
radicals.
It is also possible to use mixtures of the diamines mentioned.
Isophoronediamine is preferably used.
Polyamines having more than 2 NHZ groups are also suitable, e.g. 4-
aminomethyl-1,8-octanediamine, diethyienetriamir~e, dipropylenetriamine,
and tetraethylenepentamine.
3 0 The thermosets prepared generally have an NCO/NH2 ratio of from 0.8 to
1.2:1. If equimolar amounts are used with an NCO/NH2 ratio of 1:1, the
thermosets obtained in .the polymers are continuously crosslinked, strong,
and brittle.
For the purposes of the invention, preferred thermosets are those
composed of IPD and IPDI, and/or IPDI isocyanurate and/or HDI, and/or
HD! isocyanurate. These have molecular weights of above 4000 and
contain at least 8% by weight, preferably 20°/~ by weight, particularly
preferably 40 to 100% by weight, of isocyanurates and/or amines with
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functionality > 2, preferably isocyanurates, preferably IPDI
isocyanurate and/or HDI isocyanurate. Polyureas composed of
pure isocyanurates and IPD are also preferred.
In the preferred embodiment of the invention, from
3 to 20o by weight, particularly preferably 4, 5, 6, 7, 8,
9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19% by weight of
thermoset are present in the polymeric composition, in
particular in the OH-containing polyester or polyacrylate,
The principle of the process consists in reacting
the reactants continuously in an extruder, intensive
kneader, intensive mixer, or static mixer, through intensive
mixing and brief reaction with introduction of heat.
The process uses temperatures from 10 to 325°C,
while the temperature may vary with the product, as shown by
the examples.
This means that the residence time of t:he starting
materials in the above mentioned reactors is usually from 3
seconds to 15 minutes, preferably from 3 seconds to 5
minutes, particularly preferably from 5 to 180 seconds. The
reactants here are briefly reacted with introduction of heat
at temperatures of from 25 to 325°C, preferably from 50 to
250°C, very particularly preferably from 70 to 220°C.
Depending on the nature of the starting materials and of the
final products, these values for residence time and
temperature may, however, also adopt other preferred ranges.
In certain embodiments, the reaction may be carried out in
the presence of catalysts and/or additives.
The resultant homogeneous, mostly crumble material
can be discharged continuously. Where appropriate, a
continuous after-reaction may be attached here downstream,
or otherwise the hot product is cooled (e. g. on a cooling
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belt) and subjected to finishing (e.g. grinding) if
required.
Reactors which are particularly suitable for the
process of the invention and whose use is preferred are
extruders, such as single- or multiscrew extruders, in
particular twin-screw extruders, planetary gear extruders,
and ring extruders, intensive kneaders, intensive mixers,
and static mixers. The abovementioned extruders are very
particularly preferred.
It is surprising that the reaction, which in the
batch process needs up to 2 hours according to the prior art,
proceeds to completion in a few seconds to several minutes in
those reactors. Furthermore, the form in which t:he product
is produced is solid and to a greater or lesser extent
Z5 particulate, and, after cooling, the product can be passed
for further treatment (e.g. milling), or else directly to
storage (silo) or else packing (bagging-off) . The fact that
brief exposure to heat combined with the mixing action of the
reactors is sufficient for very substantial or complete
reaction of the reactants is of fundamental importance.
Suitable equipment in the mixing chambers of the reactors and
suitable design of the screw geometries permit intensive and
rapid mixing at the same time as intensive heat exchange.
Secondly, uniform longitudinal through-flow is provided, with
maximum uniformity of residence time. In addition, there has
to be the possibility of control to different temperatures in
each of the sections or casings of the device.
The reactants are generally fed to the reactors in
separate streams of material. If there are more than two
streams of material, these may also be introduced in a
combination. The streams of materials may also be divided,
and thus introduced to the assemblies in varying proportions
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at different locations. This method permits the controlled
setting of concentration gradients, which can bring about
completion of the reaction. The entry point for' the product
streams is sequence-variable and can be time-shifted.
It is also possible for two or more reactors to be
combined for the purpose of pre-reaction and/or completion
of the reaction.
The cooling downstream of the rapid reaction may
have been integrated into the reaction section to give an
embodiment using two or more casings, as is the case with
extruders or Conterna* machines. Use may also be made of:
tube bundles, coiled tubes, cooling rol7_ers, air conveyers,
or conveyor belts composed of metals.
Depending on the viscosity of the product leaving
the reactors or the after-reaction zone, the first finishing
process uses the abovementioned apparatus for further
cooling to a suitable temperature. This is then followed by
pelletization or else comminution to a desired particle size
by means of a roller crusher, pinned disk mill, hammer mill,
grinding mill with size classification, flaking rollers, or
the like.
The invention also provides the polymeric
composition that is a homogeneous mixture of the thermoset
in the matrix of the polymer and that is obtained through
the abovementioned solvent-free continuous process.
The composition of the invention is used as main
component, underlying component, or added component, for
applications in coating compositions, adhesives, and
sealants and insulating materials.
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The examples below provide further illustration of
the invention:
Examples
1. Preparation of polyurea in crystalline polyester
through reaction of a solution of ~PD~ isocyanurate in
isophorone diisocyanate (IPDI) with isophoronediamine
(zPD)
The polyurea is prepared from a mixture of 40% by
weight of IPDI isocyanurate and 60% by weight of IPDI as
isocyanate component and IPD as amine.
The reaction takes place in the crysta~_line
polyester DYNACOLL* 7390. The proportion of DYNACOLL* 7390
in the entire mixing specification is 79.8% by weight.
The molar ratio of NCO groups to NH2 groups is 1:1.
Besides the NH2 groups, there are OH groups present stemming
from the polyester (OH value 31.8 mg KOH/g?.
15.99 kg/h of the polyester is fed in the form of
a coarse powder into the first barrel section of a
corotating twin-screw extruder.
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The extruder has barrel sections which are separately temperature-
controllable (heatable and coolable).
Barrel section 1 is controlled to 30°C, barrel 2 to 80°C,
and the
downstream barrel sections to 120-190°C.
The isocyanate mixture is fed into barrel section 6 at a throughput rate of
2.66 kg/h with an inlet temperature of from 60 to 80°C.
The diamine is fed into barrel section 3 at a throughput rate of 1.38 kglh
with an inlet temperature of from 70 to 95°C.
The total throughput here is 20.03 kg/h.
The discharge temperature is from 100 to 115°C.
The extruder rotation rate is from 350 to 450 rpm.
The product is discharged as a white paste, which is cooled and hardened
on a cooling belt.
y5
2. Preparation of polyurea in amorphous polyester through
reaction of a solution of IPDI isocyanurate In isophorone
diisocyanate (IPDI) with is~phoronediamine (IPD)
The polyurea is prepared from a mixture of 40% by weight of IPDI
isocyanurate and 60% by weight of IPDI as isocyanate component and IPD
as amine.
The reaction takes place in the amorphous polyester URA~AC P1580. The
proportion of URALAC P1580 is 79.9% by weight of the entire mixing
specification.
The molar ratio of NCO groups to NH2 groups is 1:1. Besides the NH2
groups, there are OH groups stemming from the polyester (OH value 78.0
mg KOH/g).
15.99 kg/h of the polyester is fed in the form of a coarse powder into the
first barrel section of a corotating twin-screw extruder.
The extruder has barrel sections which are separately temperature-
controllable (heatable and coolable).
Barrel section 1 is controlled to 30°C, barrel 2 to 80°C,
and the
3 5 downstream barrel sections to 120-190°C.
The isocyanate mixture is fed into barrel section 6 at a throughput rate of
2.66 kg/h with an inlet temperature of from 60 to 80°C.
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The diamine is fed into barrel section 3 at a throughput rate of 1.37 kg/h
with an inlet temperature of from 70 to 95°C.
The total throughput here is 20.02 kg/h.
The discharge temperature is from 170 to 260°C.
The extruder rotation rate is from 350 to 450 rpm.
The product is discharged as a milky white, viscous film, which is cooled
and hardened on a cooling belt.
