COMPOSITIONS AUX POLYMERES RETARDATRICES DE LA PROGRESSION DU FEU

FLAME RETARDANT POLYMERIC COMPOUNDS

Abrégé anglais

A b s t r a c t
There are described certain polymeric compositions
which are rendered flame retarding, provide an
incandescent char-forming crust, are not dropping and
do not produce or emit toxic fumes; this is achieved
by the addition, per 100 parts by weight of polymer,
of 5-40 parts by weight of the reaction product
between an acid of phosphorus and at least one
hydroxyalkyl derivative of a-t least one compound
selected from the group isocyanuric acid, melamine
and urea, and, in a modified embodiment, in addition
to the above indicated reaction product, of 5-30
parts by weight of a polymer of an ammonium poly-
phosphate of formula (NH4PO3)n9 wherein n" is greater
than 20.
In a further modified embodiment there is added amine
phosphate, such as the ortho- or pyrophosphate of
melamine, in an amount of 1 - 10 parts by weight.
The above mentioned reaction product comprises in its
molecule the formula
N-(R)n1 -O-P
wherein R is at least one linear or branched alkylene-
derivative, n' is comprised between 1 and 6, and P is
tri- or pentavalent.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Flame retardant polymeric compositions which upon contracting
a flame , provide an intumescent char-forming crust, which are
non-dripping and promote neither flame nor toxic fumes, comprising
in 100 parts in weight of a thermoplastic polymer, from 5 to 40
parts in weight of a reaction product between an acid of phosphorus
and hydroxyalkyl derivative of isocyanuric acid, said reaction
product having a chemical structure of the type
N - (R)n1 - O - P
in which R is an alkylene derivative, and n' is between 1 and 6,
said reaction product including a plurality of nitrogen atoms
interbonded through one or more carbon atoms.
2. Flame retardant polymeric compositions which upon contacting
a flame, are non-dripping and promote neither flame nor toxic fumes,
comprising, in 100 parts in weight of a thermoplastic polymer:
(a) from 5 to 40 parts in weight of a reaction product
between an acid of phosphorus and a hydroxyalkyl
derivative of isocyanuric acid, said reaction product
having a chemical structure of the type
N - (R)n1 - O - P
in which R is an alkylenderivative, and n' is between
1 and 6, said reaction product including a plurality
of nitrogen atoms interbonded through one or more
carbon atoms: and
16

(b) from 5 to 30 parts in weight of an ammonium
polyphosphate.
3. Polymeric compositions according to claim 1 or claim 2
wherein the reaction product, the nitrogen atoms and the carbon
atoms are interbonded in an heterocyclic structure.
4. Polymeric composition according to claim 1 or claim 2
wherein the hydroxyalkyl derivative of the isocyanuric acid is
the tris (2 hydroxyethyl) isocyanurate.
S. Polymeric compositions according to claim 1 or claim 2
wherein the hydroxyalkyl derivative of the isocyanuric acid
has the formula
<IMG>
wherein R', R" and R"' are the same or different and linear
or branched alkylenic radicals containing from 1 to 6 carbon
atoms.
17

6. Polymeric compositions according to claim 1 or claim 2
wherein the molar ratio between the acid of phosphorus and the
hydroxyalkyl derivative of isocyanuric acid is between 4 : 1
and 0.1 : 4.
7. Polymeric compositions according to claim 2, wherein the
ammonium polyphosphate has a chemical structure of the type
(NH4PO3)n" wherein n" is greater than 20.
8. Polymeric compositions according to claim 1 or claim 2,
wherein the acid of phosphorus is selected from the group
consisting of H3PO3 and H3 PO4.
9. Flame retardant polymeric compositions which upon contacting
a flame, provide an intumescent char-forming crust, which are
non-dripping and promote neither flame nor toxic fumes, comprising
in 100 parts in weight of a thermoplastic polymer, from 4 to 40
parts in weight of a reaction product between an acid of phosphorus
and a hydroxalkyl derivative of isocyanuric acid, said reaction
product having a chemical structure of the type
N - (R)n1 - O - P
in which R is an alkylene derivative, and n' is between 1 and 6,
said reaction product including a plurality of nitrogen atoms
interbonded through one or more carbon atoms, wherein P is
trivalent phosphorus.
18

10. Process for producing flame retardant polymeric compositions
which upon contacting the flame, provide an intumescent char-forming
crust, which is non-dripping and promote neither flame nor toxic
fumes, the process comprising the step of reacting an acid of phos-
phorus with a hydroxyalkyl derivative of isocyanuric acid to pro-
vide a reaction product from 5 to 40 parts in weight in 100 parts
in weight of a thermoplastic polymer, said reaction product having
a chemical structure of the type
N - (R)n1 - O - P
in which R is an alkylene derivative, and n' is between 1 and 6,
and wherein said reaction product includes a plurality of nitrogen
atoms interbonded through one or more carbon atoms.
19

Description

I l~tjf~7~5 ~
~ 1~
J ~ 81
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~he present invention concern~ self e~tinguishing
polymeric compo~i~ions wh~ch, upon contacting a ~lame
provide a~ ~ char-forming c~st and do not
produce flame~ nor toxic ~umes; more particularl~
it concern tho preparation o~ a ~ynthetic orga~ic
compound which contai~ pho~phoru~ and nitrogen and
which, added to ~thetic polymer~ ~uch ~3 pol~propy-
lene9 pol~eth~lene, copolymers a~d acrylonitrile-
butadiene-styrene ble~d polymers~ polye~ters, pol~-
amide~, polycarbonates, or mixture~ o~ such polymersmutuall~ added a~d/or with ela~tomer~ and/or with
con~entional ~illers a~d additive~ la polymerlc
compo~ition~ which when co~tacting a flame, ~rovide a
charformi~g ~ crust, are ~ ~an~
do not produoe ~lame~ nor toxlc fumes~
Several proce~æe~ for making fireproo~ or
uninflammable polymers are know~ i~ the art; su¢h
proce~es are generally ba~ed upon the use of
metallic compounds, particularly antimony ones~ in
combination with thermall~ unstable h~lo~enated
compou~d3~ such as ~or example chlorinaked paraf~i~
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waxes and/or bromided organic compound~a
The art has propo~ed~ to act a~ flame-retardant and
flame barrier ~everal phosphorus containing com-
pound~, for example as disclosed in the United State~Patent No. 4,010,137, the disclo~ure of which i~
herein referred toO
The combinations "metallic compound + halogenated
compound" ~ield ~atisf~ing results a~ far AS regard8
the flame-retardant properties conferred thereby to
the polymers, but the~ are ~ubject to serious draw-
backs: corrosive phenomena in the machine~ and
installations in which the treatment of the materials
i~ performed, and intense emission of toxic fumes and
gase~ when a fire occur~. Further, acceptable flame
retardanc~ levels are obtained by making use of high
concentration of such combi~ation~ only.
It has now been surpri~i~gl~ ~ound that it i3
possible to render thermoplastic pol~mer~ of the
t~pe referred to above flame-reta~da~t~ by the
addition of a particular organic compound which doe~
not at the same time give rise to the above indicated
dr~wback~. -
~he present invention concerns flame retardant pol~-
` meric compounds which upo~ contac~ with a ~lame,
,~ esc~
provide an ~n~e~e~ char-~orming cru~t~ which
30 are ~an9d do not produce flames nor toxic
fumes~ such pol~meric compounds being characterized
b;sr comprising, per 100 parts b~ weight of a thermo-
plastic pol~mer, from 5 to 40 par-ts by weight of a
reaction product having a chemical ~tructure of the

3. ~l t~ t; 7 ~a~
t~pe.
(R)nl P
in which R is an alkylene derivative~ n' is
comprised between 1 and 6, the said reaction product
including more than one nitroge~ atoms interbonded
with one another throu~h one or morè carbon atoms;
according to a particular embodime~t~ to ~aid
reaction product there may be associated fro~ 5 to 30
parts b~ weight of a pol~mer con~isting of an ammonium
polyphosphate, and9 i~ a further modified embodiment,
amine phosphate.
According to the above said modified form the pol~mer
of ammonium polyphosphate is mixed with a~ ami~e
phosphate (ortho- or melamine pyrophosphate) in an
amount o~ 1-10 part~ by weight of amine phosphate per
hundred parts by weight o~ the thermopla3tic pol~-
mer.
~he ammoniu~ polypho~phate polymer advantageou~l~con~i~ts of an ammonium polyphosphate having a
chemical ~tructure of the t~pe (~H4P03)n,l, wherein
n" i~ greater than 20.
~n the following of the pre~ent di~closure, -the above
defined reaction product i8 indicated a~ component ~,
while the ammonium pol~phosphate polymer iB indica-ted
a~ component Bo
~he prese~t invention co~cerns also a process for
producing the reaction product formin~ the component
A) con~ist~l the proces~ bei~g characterized in that
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said reaction product is preliminarily obtained by
reacting an acid of ~hosphorus with an hydroxyalk~l
derivative~
The acid of phosphorus can be a phosphorou3 acid of
formula ~3P03, i. e~ phosphoric acid~ the propertie~
and compo~i~ion of which ma~ vary according to its
P04 contant, which can vary betweèn 50 and 120 % by
weight, and preferably from 80 and 115 %.
According to a particular embodiment of the invention
the pol~eric compositio~ is characterized by the
fact that, in the component A), the alkylene
derivative is a hydroxyaIkyl derivative of an iso-
cy~nuric acid, of a melamine or o~ a~ urea.
In some particularly preferred, though not limitative
embodiments of the invention:
a) the isocya~uric acid hydroxyalkyl derivative is
preferably the tris(2-hydroxyethyl)isocyanurate
having a nitrogen content from 15 to 17 % b~
weight, and a melting point be-tween 132 C and
138 C;
b) the hydroxyalkyl derivative of the melamine i5 a
methylol deri~ative, such as the trimethylol- or
the hexamethylolmelamine;
c) the h~droxyalk~l derivative of the urea i~ also a
methylol derivative9 in particular NN' dimethylol
urea.
The reaction product between the acid of pho~phorus

7 ~
and the or the several hydrox~alkyl derivative(s) of
the isocy~nuric acid and/or of the melamine and/or of
the urea is preferably obtained by introducing -the
reagents into a reactor provided with a stirrer, of
the two-walled t~pe heated by circulati~g warm oil,
~na provided with a degassing vacuum system. The
te~perature may vary from 140 C -to 260 C duriug the
entire reaction time~ which in turn may vary between
2 and 7 hours~
~he molar ratio between the acid ~f the phosphorus
Qnd the or the several hydroxyalkyl derivative(s) of
the isocyanuric acid and/or of the melamine and/or of
the urea is compri~ed between 4:1 and 0~1:4.
It is also possible to use s~nthesis method~ such as
the esterification of the hydroxyalkyl derivatives
which phosphorus halides or b~ mean~ of trans-
esterification reactio~s between phosphoric esters
and hydroxyalkyl derivatives.
~he reaction products forming said component A) and
the ammonium polypho~phate pol~mer forming sQid
component B) 7 a~d al~o 7 i~ the de~cribed modified
embodiment7 the amine phosphate can be added to an~
type of thermoplastic pol~mer, particularly pol~mers
and copolymers (either statistioal or block polg~ers)
e. g. of ole~ines, of pol~olefines, of vin~l monomers~
of esters and of amides~ and mi~tures of said poly-
mers with elastomers; the same ~ubstance~ and com-
pounds can also be utilized for the production of
varnishes, coatings and fibers~
The respective flame retardant composition~ are
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prepared by utilizing kno~m techniques, that is by
mixing the polymer to be rendered flame retardant,
the reactio~ products of type ~) and al~o, in the
second embodiment, the ammonium pol~pho~phate and, in
the modified embodiment, amine phosphate in a
Banbury type mixer, or two-screw extruder, operating
at the plasticization temperature of the polymer. ~he
batch or mixture thus obtained is then compression
molded at the most suitable temperature for providing
the desired articles of manufacture.
The flame retarding properties of the polymeric
compositions o~ the present invention are d~termined
by compressing the granular product into sheet having
a thickness of 3 mm, by means of a ~mall press and
operating for 7 minutes with a pressure of 40 Kg/cm
at a suitable temperature which mag var~ from polymer
to pol~mer. On the thus prepared sheets the flame
retarding level is determined either b~ measuring
(according to the ~S~M D-2863 ~pecification) the
"oxYgen index", which indicates the minimal percentage
~ 2 in a mixture 02/N2, which is required for the
sample to burn continuousl~, or al~o by making use of
the U~-94 ("Underwriters ~aboratorie~" - Y.S.h.)
specification~, which provide for an evaluation of
the flame retarding property ra~ing of the elastic
materials, and rel~ on more or les~ severe testing
condition~7 whereby to classif~ the sampl~ within a
range or echelon o~ different flame retarding
levels.
In the te~ts indicated hereinbelow in ~able I use ha~
bee~ ma~e of the "Vertical Burning Test" permitting
to clas~ify the material at decreasing levels V-O,

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V-1 a~d V-2.
Each test is made on a group of 5 samples having a
thickness of 1~8 inch, which are sustained in
vertical position, and which are primed by flame at
their lower end; two ignition attempts, each of 10
seconds, are made.
~he three flame retarding levels V-0, V-1 and V-2 are
defined as follows:
V-O = ~o sample burns for more than 10 seconds, after
each application of a flame, nor do they show
an~ dropping of ignited particles.
~urther, the total combustion time is no longer
than 10 seconds for any attempt effected on the
group of 5 samples.
V-1 = At this level, combustion times up to 30
seconds are admitted for each individual test
and up to 250 seconds for 10 attempts made on
the group of 5 samples~
At this level7 too, no sample shows a~ drop-
ing of ignited particles.
V-2 = ~t this level, the admitted combustion times
are the same as for level Y-17 but the dropping
of ignited partlcle~ is admitted.
~he several aspects of the invention are illustratea
by the following ~xamples which, however~ should not
have any limitative effect nor should they be
construed limitativel~.

J~Jit~D
~xamples 1 to 6 relate to the use of component A
only, while Examples 7 to 12 relate to the use of
component B associated to component A.
Example 1
In a 2.500 cc. reactor, 70 gr. of phosphoric acid
(~3P04 - ~5 %) are reacted with 250 gr. of tris(2-
h~droxyeth~l)isoc~anurate, under stirring at a
temperature of 150 C for 1,5 hours. ~hereafter a
vacuum of 300 mm Eg is applied and the temperature is
raised to 250 C for a period of 4 hours.
During this latter period the reaction H20 is removed
and substantial cross-linking is created in the
compound between the various molecules of the
phosphoric ester which has been formed-in the ~irst
stage of the reaction. The product is then discharged
from the cooled reactor and milled into a powder of
granules having a diameter of less than 80 microns~
~xample 2
800 gr. of phosphoric acîd (H~P03 = 85 %) are reacted
with 200 grams of tris(2-h~droxymethyl)isocyanurate
and 100 grams of tri~methylolderi~ati~e of melamineO
~he reaction is conducted in accordance with ~xample
1 and ~rom the reactor a product is di~charged which
upon cooling and milling in powder ~orm has proper-
ties substantiall~ equivalent ~o that of the product
of Example 1.

~xam~le 3
350 gr. of phosphoric acid (~P04 = 100 %) are
reacted with 200 gr. of tris(2-hydroxyethyl)iso-
cyanurate and with 300 gr. of N,N'dimethylolethylen-
urea. ~he reactio~ proceeds as described in Example
1, and the respective product also is comp~ able with
those of Examples 1 and 2.
~am~le ~
600 gr. of phosphoric acid (~3P04 = 115 %) are
reacted with 150 gr. of trishydro~yethyl isocyanurate,
150 gr. of trimethylol-derivative of melamine and 50
gr. of N,N' dimethylolurea.
~he reaction is made to proceed i~ accordance with
Example 1 and a produkt is obtained having
characteristics similar to those of the products of
the preceeding ~xamples~
~xample 5
Proceeding i~ the same way a~d under the same
conditions as in Example 1, 620 gr. of phosphoric
acid (~3P03 - 90 %) are reacted with 280 gr~ of N,~'-
dimethylolurea and with 280 gr. of hexamethylol-
~elamine: a product is discharged which i~ firstly
cooled and then ground into a powder formed of
granules of diameter less than 70 microns.

'7
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Exam~le 6
Proceeding in the same way and under same conditions
as in ~xample 1~ 800 grO of phosphoric acid
(H3P04 = 85 ~) are reacted with 300 gr. of tri-
methylolderivative of melamine, A product having
characteristics comparable to those of Example 2 is
obtained.
~he powders obtained in the preceedin~ Examples are
mixed with the thermoplastic polymers in a Banbury
type mixer at the most suitable temperature for ob-
taining a granular product, such temperature varying
from one polymer to other polymer~
The results, indicated in the following ~able as not
limitative examples, are of basic value and
importance for different thermoplastic polymers.

1 1 3 ~
TABLE I
Parts by weight
____
d ive Exa ple 30
Thermoplastic
polymer 80 75 70 80 72 75
Oxygen index 28,5 28 30 26,5 29 29,5
UL 94 (1/?'') te~t V-0 V-0 V-0 V-0 V-0 V-0
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Ex~m~le 7
50 gr. of phosphoric acid (~3P04 = 85 %) are reacted
with 250 gr. of tri~(2 h~droxyethyl) isocyanurate, in
a 2.500 cc. reactor, under stirring at a temperature
of 150 C, for 1,5 hours. Thereafter a vacuum of 300
mm Hg is applied a~d the temperature is raised to
250 C for a period of 4 hour~
During this latter time period the reaction H20 is
removed and substantial cro~s linking is promoted i~
the compound between the various molecules of the
phosphoric ester, which has been formed in the first
stage of the reaction.
~he product is discharged from the cooled reactor
and ground into a powaer the granules of which have
a diameter o~ less than 80 microns.
~xample 8
200 gr. of phosphoric acid (H3P03 = 85 ~i) ~re reacted
with 250 gram~ of tri~(2 hydrox~methyl) isocyanurate.
~he reaction is allowed to proceed according to
Example 7 and a product is extracted which after
being cooled and ground in powder-like condition ha~
characteristic substantiall~ equivalent to those o~
the product of Example 7
Exam~le 9
150 grO of phosphoric acid (H3P04 = 100 %) are
reacted with 200 gr. of ~ris(2 hydro~ethyl~ iso~
cyanurate and with 300 gr. o~ N,N' dimethylol-
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eth~lenurea. ~he reaction is allowed to proceed a3
described in Example 7, and the respective product
obtained is also comparab]e to those of Examples 7
and 8.
~xample 10
80 gr~ of phosphoric acid (H3POL~ = 115 %) are reacted
1~ with 150 gr. tris hisroxyethylisocya~urate, with 150
~r. of trimethylol derivate of melamine and 50 gr. of
N,N' dimeth~lolurea. ~he reaction is allowed to
proceed according to Example 7 and a product is ob-
tained having characteristics similar to those o~ the
products of the prece0ding Eæamples.
xam~le 11
Proceeding in the same wa~ and under the same
conditions as in Example 7~ 120 gr. of phosphoric
acid (E3P03 = 90 %) are reacted with 280 gr. of
N,N' dimeth~loleth~lurea and with 280 gr~ of hexa-
methylolmelami~e. ~he extracted product after cooling
is then ground into a powder formed of granules of
diameter less than 70 mi~rons~
xample 12
Proceeding in the same way and under the sa~e
conditions a~ in Example 7, 80 gr. of phosphoric acid
(~3P04 = 85 %) are reacted with 300 gr. of tri-
meth~lolderivative of melamine~
,

~ rr~
~- 1L~
A product having characteristics comparable to those
of Example 8 is obtained.
The powders obtained from preceeding ~xamples 7 to 12
are mixed with the tnermoplast,ic pol~mers and with
ammonium polyphosphate, and~ in the described
modified embodiment in mixture with the phosphate of
amine, in a ~an~ury t~pe mixer at the temperature
which is most suitable for obtaining a granular
product, said temperature varying from one polymer to
the other.
The results are indicated as examples in the ~ollow-
ing Table II, in which pol~propvlene is used as
polymer, (but comparable results are obtained with
other thermoplastic polymers)O
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~ABLE II
.. . . . . . .
Parts b~ weight
_ . . .i . . . __ _ . _ .
Compo~ent A of
~xample 7 15
~ol~phosphate NH4 15
... _ ......... . . . _ . .
Component A of
E~ample 8 10
Polyphosphate NH4 15
Orthophosphate of
melamine 15
.
Component A of
Example 9 15
Polyphosphate ~H4 10
Pyropho~phate of
melamine 10
.. _ _ . . . . _ . _
Component A of
Example 10 20
Polyphosphate N~4 10
_ _ . . _ _ ~ _ .. . . _ _ . . _
Component A of
Example 11 18
Pol~phosphate NH4 12
Component ~ of
Example 12 20
Polyphosphate NH4 15
_ _ . . . _ _
~hermoplastic
pol~Mer
Polypropylene
Melt index 10 70 70 65 - 7 7 65
O.x~gen index 33,5 32 30 28,5 29 29,5
UL 94 (1/9ll) test V~O V-O V-O V-O V~O V-O
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