Note: Descriptions are shown in the official language in which they were submitted.
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FLAME-RETARDING COMPOSITION AND PROCESS FOR THE
PREPARATION THEREOF
The invention relates to a flame-retarding
composition and a process for the preparation thereof.
A flame-retarding composition and a process
for the preparation thereof are for example described
in the Japanese patent publication JP 59-45352, in
which the melamine condensation products melem and
melon are prepared and used as flame retardants in
polyamide compositions. In this publication melem is
prepared by heating melamine at a temperature of 400 -
500°C for several hours. Melon is prepared by heating
melamine at 500 - 550°C until no more ammonia is
released. JP 59-45352 mentions that the decomposition
temperature of melem lies above 500°C and that of melon
above 600°C. This means that melem and melon have a
particularly good thermal stability. According to
JP 59-45352, the nitrogen contents of both compounds
lie above 600, as a result of which the substances are
non-combustible. JP 59-45352 also mentions that other
known flame retardants can also be used in combination
with melem or melon, for example melamine, cyanuric
acid, melamine cyanurate or melam. JP 59-45352 does not
mention the composition of the product obtained.
Melamine and its condensation products all
have a characteristic thermal degradation curve. This
means that melamine and its condensation products
decompose to form nitrogen-containing products at a
certain temperature. These nitrogen-containing products
that are released in the thermal degradation play an
important part in the flame-retardant behaviour. To
obtain good flame-retardant behaviour in polymers it
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may be favourable to combine flame=retarding
components, such as melam, melem and the higher
condensation products of melamine and/or melem, having
different degradation characteristics, in a single
composition. The advantage of this is that,
irrespective of the temperature prevailing in a fire,
there will almost always be a component present that
degrades at the prevailing temperature and produces
sufficient nitrogen-containing components having a
flame-retarding effect. However, if the flame-retarding
composition contains volatile components, such as urea
and/or water, this will have a negative effect on the
processing properties when the composition is used in
polymers with a high melting temperature, for example
in polyesters such as polyethylene terephthalate (PET)
or polybutylene terephthalate (PBT) or in polyamides.
Such a negative effect could be foaming during
extrusion or the formation of deposits on the mould in
injection-moulding. If the flame-retarding composition
contains too high a concentrationm of higher
condensation products of melamine and/or melem, the
composition will be yellow, which is undesirable in the
case of processing in (uncoloured) polymer
compositions. The use of pure melamine condensation
products such as pure melam or melem or melon as a
flame retardant in polymers is unfavourable because it
will usually be difficult, and hence expensive, to
prepare pure compounds and because pure components have
only one mode of degradation and will hence work
optimally only in a limited temperature range.
The applicant has discovered that excellent
processing properties and excellent flame-retarding
properties and colour properties can be obtained in
polymer compositions by using a flame-retarding
composition containing:
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- 90 wt.o melem,
0.01 - 30 wt.% melam,
0.01 - 15 wt.% melamine,
0.1 - 65 wt.% higher condensation products of
5 melamine and/or melem, the concentration of volatile
components being lower than 3 wt.% and the sum of the
individual components amounting to 100 wt.%.
The concentration of volatile components is
here defined as the decrease in weight that occurs in
10 heating the flame-retarding composition from room
temperature to 300°C in a TGA measurement (TGA =
thermogravimetric analysis) at a heating rate of 200°C
per minute.
The applicant has also found a process for
preparing a flame-retarding composition comprising 10
90 wt.% melem, 0.01 - 30 wt.% melam, 0.01 - 15 wt.%
melamine, 0.1 - 65 wt.o higher condensation products of
melamine and/or melem, the concentration of volatile
components being lower than 3 wt.o and the sum of the
individual components amounting to 100 wt.%, by heating
a starting product containing melamine, for example by
passing it through a heating zone, for longer than 0.1
sec., preferably 1 sec. to 400 minutes, in particular 2
sec. to 300 minutes, at a temperature of 350 - 800°C,
preferably between 375 and 600°C and at a pressure
between 1 KPa and 50 MPa, preferably between
atmospheric pressure and 30 MPa, more in particular
between atmospheric pressure and 15 Mpa.
Examples of heating zones are heating zones
of the kind that are to be found in extruders, such as
single- and twin-screw extruders; autoclaves; turbo
mixers; plough blade mixers; tumble mixers; turbulence
mixers; ribbon-blade mixers; mixtruders; continuous and
discontinuous kneading machines; rotating drum ovens,
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etc.
A mixture of melamine, melem, melam and
higher condensation products of melamine and/or melem
can optionally be obtained by treating the product of
the heating further, to obtain a flame-retarding
composition comprising 10 - 90 wt.% melem, 0.01 - 30
wt.% melam, 0.01 - 10 wt.% melamine, 0.1 - 65 wt.%
higher condensation products of melamine and/or melem,
the concentration of volatile components being lower
than 1 wt.% and the sum of the individual components
amounting to 100 wt.o. This further treatment is
preferably washing with water to dissolve and remove
from the flame-retarding composition a portion of the
melamine and/or other water-soluble components.
As the starting material for the present
process, use can be made of virtually pure melamine, as
for example obtained from a continuously operating gas-
phase melamine plant where the melamine is purified by
means of crystallisation. A method for the preparation
of melamine via a gas-phase process is for example
known from US-A-3210352. This high degree of purity is
however not necessary. Melamine contaminated with melam
and/or melem and/or higher condensation products of
melamine and/or melem can optionally be used as the
starting material, for example the product that is
formed during start-up of a melamine plant or melamine
of the kind that is prepared in a gas-phase melamine
plant before purification by means of crystallisation
has taken place or melamine contaminated with melam
and/or melem and/or higher condensation products of
melamine and/or melem formed in some other way. It is
also possible to use melamine obtained in a liquid-
phase process as the starting material. A known process
for the preparation of melamine via a liquid-phase
process is described in US-A-4565867, of which it is
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known that the degree of purity is less than that of
the product of a gas-phase process; in particular, its
melam content is higher. Contaminants like residual
catalyst, ureidomelamine and/or guanidine carbonate may
also be present without any objection. Oxygen-
containing triazine compounds such as ammeline,
ammelide and/or cyanuric acid may also be present up to
5 wt.% without any objection. Remains of the starting
materials used for the preparation of melamine, such as
urea and/or dicyanodiamide, may also be present;
dicyanodiamide may be present up to 10 wt.% without any
objection, while the melamine may contain up to 30 wt.%
urea. The starting material for the present process may
also contain contaminants containing mixtures of urea,
oxygen-containing triazine compounds, dicyanodiamide,
guanidine carbonate, ureidomelamine and residual
catalyst.
In a preferred embodiment of the invention
the flame-retarding composition is prepared by heating
the melamine-containing starting product in an
autoclave or in an extruder. Preferably at a pressure
between atmospheric pressure and 20 Mpa, at a
temperature of 350-625°C and with a residence time of
between 0.1 sec. and 360 minutes. More in particular
the heating of the melamine-containing starting product
is carried out in an extruder with a residence time in
the extruder of between 0.1 sec. and 60 minutes.
The invention also relates to flame-
retarding polymer compositions comprising the following
components:
a. 65 - 95 wt.% polymer-containing composition
b. 5 - 35 wt.% flame-retarding composition according
to the invention
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The flame-retarding composition according
to the invention is particularly suitable for use in
polymer compositions requiring heat-resistant flame
retardants, for example in polyamides, polyimides,
polyesters, styrene-containing polymers, epoxy resins,
unsaturated polyester resins and polyurethanes.
Examples of polyamides are polyamides and
copolyamides derived from diamines and dicarboxylic
acids and/or from aminocarboxylic acids or the
corresponding lactams, such as polyamide 4, polyamide
6, polyamides 6/6, 6/10, 6/9, 6/12, 4/6, 66/6, 6/66,
polyamide 11, polyamide 12, partially aromatic
(co)polyamides, for example polyamides based on an
aromatic diamine and adipic acid; polyamides prepared
from an alkylene diamine and iso- and/or terephthalic
acid and copolyamides thereof, copolyether amides,
copolyester amides, etc.
Examples of polyesters are polyesters
derived from dicarboxylic acids and dialcohols and/or
from hydroxycarboxylic acids or the corresponding
lactones such as polyethylene terephthalate,
polybutylene terephthalate, poly-1,4-
dimethylolcyclohexane terephthalate,
polyhydroxybenzoates, polycaprolactone and copolyesters
thereof, copolyether esters, etc.
Examples of styrene-containing polymers are
polystyrene, acrylonitrile-styrene copolymer,
acrylonitrile-styrene-butadiene copolymers and mixtures
hereof.
Preferably the flame-retarding composition
is used in polyesters such as polyethylene
terephthalate and/or polybutylene terephthalate,
polybutylene terephthalate being particularly
preferable, or in polyamides such as nylon-6, nylon 6,6
or nylon 4,6.
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"Polymer-containing compositions" are
understood to be compositions which, in addition to
polymer, may also contain reinforcing agents and/or
fillers, compounds that have a synergetic effect with
the flame-retarding composition, other flame-retarding
components than those according to the invention, plus
the usual additives.
If reinforcing agents and/or fillers are
used in the polymer composition of the invention, their
concentration may vary within a wide range, partly
determined by the level of mechanical properties one
wishes to achieve. In general, the concentration of
reinforcing agents will be no more than 50 wt.% in the
reinforced flame-retarding polymer composition.
Preferably the reinforced flame-retarding polymer
composition will contain 5-50 wt.% reinforcing agents,
more preferably 15-45 wt.%. The reinforcing agents can
be chosen from the group comprising inorganic
reinforcing agents, such as mica, clay, talc or glass
fibres, or aramide fibres and/or carbon fibres. Glass
fibres are however preferable.
The flame-retarding effect of the flame-
retarding composition according to the invention can be
reinforced by the presence of a compound that has a
synergetic effect with the flame-retarding composition,
such as a carbon-forming compound, whether or not
combined with a catalyst promoting the formation of
carbon. In general the concentration of the flame-
retarding composition can then be chosen to be lower.
In principle, all the known substances that
reinforce the effect of flame-retarding compositions
can be used as carbon-forming compounds. Examples are
phenolic resins, epoxy resins, melamine resins, alkyd
resins, allyl resins, unsaturated polyester resins,
silicone resins, urethane resins, acrylate resins,
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polyphenylene ether, polycarbonate, starch, glucose and
compounds containing at least two hydroxyl groups.
Examples of compounds containing at least two hydroxyl
groups are alcohols containing at least two hydroxyl
groups, for example pentaerythritol, dipentaerythritol,
tripentaerythritol and mixtures hereof. The
concentration of the carbon-forming compound having a
synergetic effect with the flame retardant in the
overall polymer composition will generally lie between
0 and 30 wt.%, preferably between 1 and 20 wt. o.
As the catalyst promoting the formation of
carbon use can for example be made of metal salts of
tungstic acid; a complex acid oxide of tungsten with a
metalloid; salts of tin oxide; ammonium sulphamate
and/or the dimer hereof. Metal salts of tungstic acid
are preferably alkali metal salts of tungstic acid, in
particular sodium tungstate. A "complex acid oxide of
tungsten with a metalloid" is understood to be complex
acid oxides which are formed from a metalloid such as
silicon or phosphorus and tungsten, such as
silicotungstic acid or phosphorotungstic acid. The
amount of catalyst promoting the formation of carbon
that is used in the overall polymer composition is 0.1
- 5 wto, preferably 0.1 - 2.5 wt%.
The flame-retarding effect of the flame-
retarding composition according to the invention can be
further reinforced by using one or more other flame-
retarding components. In principle, all the known flame
retardants can be used as the other flame-retarding
components. Examples are antimony oxide, for example
antimony trioxide, combined with halogen compounds;
alkali earth metal oxides, for example zinc oxide,
magnesium oxide; other metal oxides, for example
alumina, silica, iron oxide and manganese oxide; metal
hydroxides, for example magnesium hydroxide and
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aluminium hydroxide; metal borates; for example zinc
borate, whether or not hydrated; and phosphorus-
containing compounds. Examples of phosphorus-containing
compounds are zinc phosphate, ammonium phosphate,
ammonium pyrophosphate, ammonium polyphosphate,
ethylene-diamine phosphate, piperazine phosphate,
piperazine pyrophosphate, melamine phosphate,
dimelamine phosphate, melamine pyrophosphate, melamine
polyphosphate, melam phosphate, melam pyrophosphate,
melam polyphosphate, melem phosphate, melem
pyrophosphate, melem polyphosphate, guanidine
phosphate, dicyanodiamide phosphate, urea phosphate and
phosphates, pyrophosphates and polyphosphates of higher
condensation products of melamine and/or melem and
mixtures of these phosphates. The acids, salts, mixed
acid salts, esters, partial esters and mixed esters of
phosphates can also be used. Use may also be made of
phosphine oxides, phosphine sulphides and
phosphorinanes and of phosphonates, phosphates and
phosphinates and of their acids, salts, mixed acid
salts, esters, partial esters and mixed esters. The
concentration of other flame-retarding components that
can be used may vary within a wide range but will
generally not be higher than the concentration of
flame-retarding composition according to the invention.
Preferably the amount will be between 0 and 35 wt.%,
more in particular 1 and 20 wt.%. Preferably use is
made of phosphates, phosphinates and phosphonates.
Examples of such compounds are for example described in
Kirk Othmer, Encyclopedia of Chemical Technology,
Volume 10, pp. 396-419 (1980). Well-known examples are:
the esters of trimethylol propane and methyl phosphonic
acid, ethyl-methyl phosphinic acid and the aluminium
salt of ethyl-methyl phosphinic acid. Many of the
compounds mentioned here may also promote the formation
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of carbon. Other known compounds present in flame-
retarding compositions such as polytetrafluoroethylene
may also be present.
The polymer composition may also contain
the other usual additives, such as heat and UV
stabilisers, mould-release agents, plasticisers,
softeners, lubricants, dispersing agents, colourants
and/or pigments, in amounts generally used for these
additives insofar as the properties are not adversely
affected.
The polymer composition according to the
invention can be prepared using the conventional
techniques known per se, by for example mixing all or
some of the components in dry condition in a tumble
mixer, followed by melting in a melt mixer, for example
a Brabender mixer or a single- or twin-screw extruder
or a kneading machine. Preferably a twin-screw extruder
is used.
The various components of the polymer
composition of the invention may be dosed to the
extruder's throat together. They may also be dosed to
the extruder in different places. Some of the
components, for example colourants, stabilisers, the
flame-retarding composition, compounds having a
synergetic effect with the flame-retarding composition
and/or other flame-retarding components may for example
be added to the polymer in the form of a masterbatch.
The polymer composition according to the
invention can be processed into semi-finished products
or end products using techniques known to a person
skilled in the art, for example injection-moulding.
The invention will be further elucidated
with reference to the following examples:
Comparative example A
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Melamine (product of a gas-phase process
from DSM) was dosed to a corotating twin-screw extruder
(Werder & Pfleiderer, type ZSK 30/33) at a rate of 3 kg
per hour. The cylinder temperature had been set to 330°C
and the screw speed to 40 rpm. The residence time of
the components dosed to the extruder was 115 seconds.
The solid mixture leaving the extruder was white and
had the following composition: 88 wt.% melamine, 6 wt.%
melam, 2 wt.% melem and 4 wt.% higher condensation
products of melamine and/or melem. The volatiles
content is 1.6 wt.%. The composition of the flame-
retarding composition was determined with the aid of
high-pressure liquid chromatography (HPLC). The values
obtained have a relative error of 5% or less.
Example 1
Melamine (product of a gas-phase process
from DSM) was dosed to a corotating twin-screw extruder
(Werder & Pfleiderer, type ZSK 30/33) at a rate of 1 kg
per hour. The cylinder temperature had been set to 400°C
and the screw speed to 40 rpm. The residence time of
the components dosed to the extruder was approximately
95 seconds. The solid mixture leaving the extruder was
white to pale beige and had the following composition:
8 wt.% melamine, 0.5 wt.% melam, 73 wt.o melem and 18.5
wt.o higher condensation products of melamine and/or
melem. The volatiles content is 0.4 wt.%. The
composition of the flame-retarding composition was
determined with the aid of high-pressure liquid
chromatography (HPLC).
Example 2
Melamine (product of a gas-phase process
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from DSM) was dosed to a corotating twin-screw extruder
(Werder & Pfleiderer, type ZSK 30/33) at a rate of 2 kg
per hour. The cylinder temperature had been set to 450°C
and the screw speed to 40 rpm. The residence time of
the components dosed to the extruder was approximately
100 seconds. The solid mixture leaving the extruder was
white to pale beige and had the following composition:
1.3 wt.% melamine, 0.1 wt.% melam, 64 wt.% melem and
23.7 wt.% higher condensation products of melamine
and/or melem. The volatiles content is 0.1 wt.%. The
composition of the flame-retarding composition was
determined with the aid of high-pressure liquid
chromatography (HPLC).
Example 3
Melamine (product of a gas-phase process
from DSM) was dosed to a corotating twin-screw extruder
(Werder & Pfleiderer, type ZSK 30/33) at a rate of 3 kg
per hour. The cylinder temperature had been set to 450°C
and the screw speed to 40 rpm. The residence time of
the components dosed to the extruder was 80 seconds.
The solid mixture leaving the extruder was white to
pale beige and had the following composition: 1 wt.%
melamine, 0.1 wt.% melam, 86 wt.% melem and 12.9 wt.%
higher condensation products of melamine and/or melem.
The volatiles content is 0.2 wt.%. The composition of
the flame-retarding composition was determined with the
aid of high-pressure liquid chromatography (HPLC).
Example 4
1008 grams (8mol) of melamine was
introduced into an autoclave with a volume of about
2000 ml. The stirrer was started at a speed of approx.
30 rpm. The reactor was then brought to the required
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temperature. The reaction temperature was 500°C. The
ammonia pressure in the autoclave, which was built up
during the reaction, was kept at approx. 2 Mpa with the
aid of a control valve. The reaction time was 60
minutes. The autoclave was then cooled. The pressure in
the autoclave was maintained during the cooling. The
ammonia pressure was relieved as soon as the
temperature dropped below 200°C. The solid mixture
leaving the autoclave was white to pale beige and had
the following composition: 0.4 wt.% melamine, 0.5 wt.%
melam, 91 wt.o melem and 8 wt.% higher condensation
products of melamine and/or melem. The volatiles
content was 0.1 wt.%. The composition of the flame-
retarding composition was determined with the aid of
high-pressure liquid chromatography (HPLC).
Example 5
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) was fed with: 45 parts
polybutylene terephthalate, 30 parts glass fibre, 15
parts ground product of Example 2 and 10 parts
Antiblaze~ 1045 (cyclic phosphonate ester from
Albright&Wilson). The cylinder temperature had been set
to 250°C and the screw speed to 200 rpm. Specimens with
a thickness of 1.6 mm were produced from the compound
obtained and tested. The burning behaviour according to
UL 94 was V-0. The modulus of elasticity was 10.1 GPa
and the elongation at break was 2.0 %(ISO 527/1).
Example 6
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) was fed with: 45 parts
polybutylene terephthalate, 30 parts glass fibre, 15
parts ground product of Example 3 and 10 parts
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Antiblaze~ 1045 (cyclic phosphonate ester from
Albright&Wilson). The cylinder temperature had been set
to 250°C and the screw speed to 200 rpm. Specimens with
a thickness of 1.6 mm were produced from the compound
obtained and tested. The burning behaviour according to
UL 94 was V-0. The modulus of elasticity was 10.0 GPa
and the elongation at break was 2.0 %(ISO 527/1).
Example 7
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) was fed with: 45 parts
polybutylene terephthalate, 30 parts glass fibre, 15
parts ground product of Example 4 and 10 parts
Antiblaze~ 1045 (cyclic phosphonate ester from
Albright&Wilson). The cylinder temperature had been set
to 250°C and the screw speed to 200 rpm. Specimens with
a thickness of 1.6 mm were produced from the compound
obtained and tested. The burning behaviour according to
UL 94 was V-0. The modulus of elasticity was 10.2 GPa
and the elongation at break was 2.1 %(ISO 527/1).
Example 8
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) was fed with: 45 parts
polyamide 6, 20 parts glass fibre, 30 parts ground
product of Example 4 and 5 parts Antiblaze~ 1045
(cyclic phosphonate ester from Albright&Wilson). The
cylinder temperature had been set to 250°C and the screw
speed to 200 rpm. Specimens with a thickness of 1.6 mm
were produced from the compound obtained and tested.
The burning behaviour according to UL 94 was V-0. The
modulus of elasticity was 11.2 GPa and the elongation
at break was 2.0 %(ISO 527/1).
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Example 9
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 25/38) was fed with: 80 parts
polyamide 4,6 arid 20 parts ground product of Example 3.
The cylinder temperature had been set to 300-315°C and
the screw speed to 270 rpm. Specimens with a thickness
of 1.6 mm were produced from the compound obtained and
tested. The burning behaviour according to UL 94 was V-
0. The modulus of elasticity was 3.6 GPa and the
elongation at break was approximately 25% (ISO 527/1).
Example 10
A corotating twin-screww extruder (Werder &
Pfleiderer, type ZSK 25/38) was fed with: 90 parts
polyamide 4,6 and 10 parts ground product of Example 3.
The cylinder temperature had been set to 300-315°C and
the screw speed to 270 rpm. Specimens with a thickness
of 1.6 mm were produced from the compound obtained and
tested. The burning behaviour according to UL 94 was V-
0. The modulus of elasticity was 2.3 GPa and the
elongation at break was 30% (ISO 527/1).
Example 11
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) was fed with: 80 parts
polyamide 6,6 and 20 parts ground product of Example 3.
The cylinder temperature had been set to 270-280°C and
the screw speed to 200 rpm. Specimens with a thickness
of 1.6 mm were produced from the compound obtained and
tested. The burning behaviour according to UL 94 was
V-0.
Example 12
A corotating twin-screw extruder (Werder &
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Pfleiderer, type ZSK 30/33) was fed with: 80 parts
acrylonitrile-butadiene-styrene (Ronfalin~ from DSM
containing 20 parts rubber) and 20 parts ground product
of Example 3. The cylinder temperature had been set to
180-210°C and the screw speed to 200 rpm. Specimens with
a thickness of 1.6 mm were produced from the compound
obtained and tested. The burning behaviour according to
UL 94 was V-0.
Example 13
A mixture of 98.0 % melamine, 0.81% urea,
0.03% C02, 0.05% ammeline-related impurities (such as
ammeline, ammelide, cyanuric acid and uridomelamine)
and 0.07% organic solids (melem, melam and other
oxygen-free compounds), as obtained in the process
according to US4565867, was dosed to a corotating twin-
screw extruder (Werder & Pfleiderer, type ZSK 30/33) at
a rate of 8 kg per hour. The cylinder speed had been
set to 450°C and the screw speed to 40 rpm. The
residence time of the components dosed to the extruder
was 110 seconds. The solid mixture leaving the extruder
was white to pale beige and had the following
composition: 7 wt.% melamine, 2 wt% melam, 76 wt.%
melem, 14 wt.% higher condensation products of melamine
and/or melem, and an unidentified residual fraction of
approx. 1 wt.% The volatiles content is 0.2 wt.%. The
composition of the flame-retarding composition was
determined with the aid of high-pressure liquid
chromatography (HPLC).
Example 14
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) was fed with: 45 parts
polybutylene terephthalate, 30 parts glass fibre, 15
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parts ground product of Example l3 and 10 parts
Antiblaze~ 1045 (cyclic phosphonate ester from
Albright&Wilson). The cylinder temperature had been set
to 250°C and the screw speed to 200 rpm. Specimens with
a thickness of 1.6 mm were produced from the compound
obtained and tested. The burning behaviour according to
UL 94 was V-0. The modulus of elasticity was 10.0 GPa
and the elongation at break was 2.4 0 (Iso 527/1).
Example 15
Melamine with a purity of 99.92 % as
obtained in the process according to US3210352 was
dosed to a corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) at a rate of 8 kg per hour.
The cylinder speed had been set to 450°C and the screw
speed to 40 rpm. The residence time of the components
dosed to the extruder was 110 seconds. The solid
mixture leaving the extruder was white to pale beige
and had the following composition: 6 wt.% melamine, 1
wt% melam, 77 wt.% melem, 16 wt.% higher condensation
products of melamine and/or melem. The volatiles
content is 0.3 wt.%. The composition of the flame-
retarding composition was determined with the aid of
high-pressure liquid chromatography (HPLC).
Example 16
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) was fed with: 45 parts
polybutylene terephthalate, 30 parts glass fibre, 15
parts ground product of Example 15 and 10 parts
Antiblaze~ 1045 (cyclic phosphonate ester from
Albright&Wilson). The cylinder temperature had been set
to 250°C and the screw speed to 200 rpm. Specimens with
a thickness of 1.6 mm were produced from the compound
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obtained and tested. The burning behaviour according to
UL 94 was V-0. The modulus of elasticity was 10.5 Mpa
and the elongation at break was 2.2 % (Iso 527/1).
Example 17
A mixture of 98.7 % melamine, 1.0 % urea,
0.06% C02, 0.1% ammeline-related compounds (such as
ammeline, ammelide and cyanuric acid) and 0.12%
organic solids (melem, melam and other compounds) and
0.02% (200ppm) residual inorganic catalyst, as obtained
after the quenching and before the crystallisation step
according to the process described in US3210352, was
dosed to a corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) at a rate of 8 kg per hour.
The cylinder speed had been set to 450°C and the screw
speed to 40 rpm. The residence time of the components
dosed to the extruder was 110 seconds. The solid
mixture leaving the extruder was white to pale beige
and had the following composition: 6 wt.% melamine, 1
wt% melam, 74 wt.% melem, 20 wt.% higher condensation
products of melamine and/or melem. The volatiles
content is 0.3 wt.%. The composition of the flame-
retarding composition was determined with the aid of
high-pressure liquid chromatography (HPLC).
Example 18
A corotating twin-screw extruder (Werder &
Pfleiderer, type ZSK 30/33) was fed with: 45 parts
polybutylene terephthalate, 30 parts glass fibre, 15
parts ground product of Example 17 and 10 parts
Antiblaze~ 1045 (cyclic phosphonate ester from
Albright&Wilson). The cylinder temperature had been set
to 250 °C and the screw speed to 200 rpm. Specimens with
a thickness of 1.6 mm were produced from the compound
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obtained and tested. The burning behaviour according to
UL 94 was V-0. The modulus of elasticity was 10.2 GPa
and the elongation at break was 2.0 % (Iso 527/1).
Example 19
Melamine (product of a gas-phase process
from DSM) was dosed to a corotating twin-screw extruder
(Werder & Pfleiderer, type ZSK 30/33) at a rate of 1 kg
per hour. The cylinder temperature had been set to 400°C
and the screw speed to 40 rpm. The residence time of
the components dosed to the extruder was 95 seconds.
The solid mixture leaving the extruder was ground. The
ground product was washed in portions of about 200
grams in 3 litres of water of approximately 90°C. After
15 minutes the hot slurry was removed through
filtration. The residue was treated three more times
according to the same procedure. The washed product was
ultimately dried at 120°C in a vacuum drying oven until
it contained less than 1 wt.% water. The product thus
obtained was white and had the following composition: 1
wt.% melamine, 2 wt.% melam, 77 wt.% melem and 20 wt.o
higher condensation products of melamine and/or melem.
The volatiles content is less than 0.3 wt.%. The
composition of the flame-retarding composition was
determined with the aid of high-pressure liquid
chromatography (HPLC).
