Note: Descriptions are shown in the official language in which they were submitted.
lOSZ027
Back~round of the Invention
Compounds which are useful in polymeric compositions of the
present invention can be characteri~ed as pentaerythritol cyclic
diphosphates and diphosphoramidates. The diphosphates are further
characterized by halogen substitution on the oxyaliphatic or oxy-
alicyclic groups of the ester moiety. The diphosphoramidates can
be optionally substituted with halogen atoms on the hydrocarbon
substituents attached to the nitrogen atoms.
During the past several years, a large number of flame
retardants have been developed for use with an almost equally
large number of flammable materials. Cellulosic materials such
as paper and wood and polymeric materials such as synthetic fibers
and bulkier plastic articles are just two examples of materials
for which flame retardants have been developed. For any class of
1ammable materials, such as synthetic high polymers, those
skilled in the art have long been aware that some flame retardant
additives are more effective in polymers and polymeric compositions
than other flame retardant additives. This is because the efficacy
of any flame retardant in polymers or polymeric compositions is
measured not only by the flame retarding capability of the addi-
tive but also by the ability of the additive to improve or modify,
or at least not to detract from, other physical or mechanical
properties of the polymer or polymeric composition. The mere
fact, therefore, that most flame retardants contain halogen and
-2-
1052027
phosphorus atoms does not assure that any given halogenated or
;- phosphorus-containing compound will impart useful flame retardant
characteristics to all or even to any polymeric systems. Further-
more, as those skilled in the art have improved the flame retar-
dancy of many polymeric materials, they have been simultaneously
required to provide the necessary flame retardancy with a minimal
effect upon other properties of the polymers such as their light
stability, processability and flexural, tensile and impact
strengths. Balancing all of the foregoing considerations and
thereby developing polymeric compositions with good flame retar-
dant characteristics as we~ll as a satisfactory balance of other
properties is, consequently, a task which has in the past and
presently continues to require the exercise of a high degree of
inventive skill.
, . .
Summary of the Invention
- Providing new compounds capable of imparting useful flame
retardant characteristics to natural and synthetic polymer systems
constitutes one of the principal objects of this invention. Addi-
` tional objects will become apparent from the following detailed
disclosure.
Providing a method for rendering natural and synthetic
polymers flame retardant through the addition of certain additives
is another principal object of the invention.
The present invention pertains to polymeric compositions
comprising a polymer and a flame retarding amount of a compound
having the generic formula
X X
1` ~o--CH2~ ~CH2 \/p~_y
O--CH2 CH2--'
.. .. ....
105Z027
where X and Xl are each oxygen or sulfur and Y and Yl are each
monovalent halogenated oxyaliphatic or oxyalicyclic or
R
N
.. . Rl
where R and Rl are each hydrogen, monovalent hydrocarbon or halo-
gena.ed monovalent hydrocarbon.
Another aspect of the invention pertains to a method for
rendering polymers flame retardant comprising combining said
polymers with a flame retarding amount of one or more of the
compounds described above.
Descrip _on of the Preferred Embodiments
.. .
The compounds of the above formula include both the diphos-
j phate esters and the diphosphoramidates of pentaerythritol. The
compounds can also be generically described as 3,9-substituted-
2,4,8,10-tetraoxa-3,9-diphosphaspiro ~.5] undecane-3,9-dioxide or
disulfides.
As indicated by the generic formula, the X groups attached ~-
to the phosphorus atoms can be either sulfur or oxygen. Oxygen
is the preferred substituent for most compounds included herein,
but the presence of thiophosphoryl groups, i.e.
S
may be advantageous in some situations because of the difference
in properties caused by their presence in place of the more
~ customary phosphoryl groups.
The Y groups can be monovalent halogenated oxyaliphatic or
oxalicyclic groups or an amino group of the formula
--4--
10520Z7
R
; \
Rl
where the R and Rl groups are hydrogen, monovalent hydrocarbon or
halogenated monovalent hydrocarbon. The oxyaliphatic and oxyali-
;l .
~ cyclic groups can be alkoxy, olefinicoxy and cycloalkoxy groups
., .
having any number of carbon atoms, preferably not more than about
12 carbon atoms and more preferably not more than about six carbon
atoms. The halogen atoms present on the oxyaliphatic and oxyali-
' cyclic groups include fluorine, chlorine, bromine and iodine. Of
`~ the foregoing, chlorine and bromine are preferred. The number of
~ 10 halogen substituents is limited only by the number of sites on
,~,.
the aliphatic or alicyclic group available for their substitution.
- From a practical standpoint, the number of halogen atoms present
on aliphatic or alicyclic groups having six or less carbon atoms
will usually be from about one to about six. Examples of suitable
il halogenated monovalent oxyaliphatic or oxyalicyclic groups include
bromoethoxy, dibromoethoxy, dibromopropoxy, dibromobutadieneoxy,
tribromobutoxy, dichlorocyclohexoxy, dichlorobromocyclohexoxy,
chlorodibromopropoxy, chlorodibromoeopentyloxy, difluorochloro-
ethoxy, bromoiodopropoxy, difluorochlorohexoxy, dichlorohexabromo-
iodohexenoxy, iodethoxy, chlorope~tabromocyclohexoxy, fluoro-
hexabromobutoxy, tetrafluorocyclobutoxy, diiodobuteneoxy, difluoro-
allyloxy, dibromodichlorohexeneoxy and the like
When the Y groups are oxyaliphatic groups it is preferred
that said groups each be
1052027
l H2Z 1
O--CH2-- I CH2Z2
CH2Z3
wherein Zl and Z2 are independently selected from fluorine,
chlorine, bromine, iodine, and hydrogen and Z3 is selected from
fluorine, chlorine, bromine, and iodine. Examples of suitable
groups of the above neopentyloxy structure are listed in Table I,
infra. Table I is for purposes of illustration only and is not
to be construed as a limitation on the scope of this invention.
The following is a partial listing of those preferred compounds
which have the above neopentyloxy moiety: 3,9-bis(2,2- Ldibromo-
methy~ -3-bromopropoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.3 -
undecane-3,9-dioxide, 3,9-bis(2,2- [dichloromethy~ -3-chloropropoxy)-
. 2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane-3,9-dioxide,
., . _ _
3,9-bis(2,2- dimethyl -3-chloropropoxy)-2,4,8,10-tetraoxa-3,9-
diphosphaspiro ~5.~ undecane-3,9-dioxide, 3,9-bis(2,2- ~imethy~ -3-
bromopropoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro t5.53 undecane-
3,9-dioxide, and 3,9-bis(2,2- ~ibromomethy~ -3-chloropropoxy)-2,-
4,8,10-tetraoxa-3,9-diphosphaspiro [5.~ undecane-3,9-dioxide.
TABLE I
Group Zl Z2 Z3
1 Br Br Br
2 Cl Cl Cl
3 H H Cl
4 H H Br
i 5 Br Cl Br
--6--
....~,..~ .
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The Y groups can also be amino groups of the formula
N
\
where R and Rl are hydrogen, monovalent hydrocarbon or halogenated
monovalent hydrocarbon.
The monovalent hydrocarbon groups can be aliphatic, alicyclic
or aromatic and can be of any size, preferably not more than about
twelve carbon atoms, more preferably not more than about six
carbon atoms. Preferred monovalent hydrocarbon groups are phenyl
and alkyl groups having up to about six carbon atoms. The halogen
atoms can be fluorine, chlorine, bromine or iodine and preferably
are chlorine or bromine. The number of halogen atoms present on
the R groups is limited only by the sites on the R groups available
for substitution. Preferably, each of the R groups will usually ~ -
contain a maximum of about six halogens per R group, and more
preferably a maximum of about three halogens per R group.
The monovalent hydrocarbon groups are preferably aliphatic,
halogenated aliphatic, aromatic, or halogenated aromatic groups
containing not more than about 12 carbon atoms, said halogenated
groups having up to about six halogen substituents per group.
~0 Examples of suitable amino groups include amino, diethylamino,
diphenylamino, propylamino, methylamino, dimethylamino, N-phenyl,
N-methylamino, phenylamino, p-tolylamino, bromophenylamino, chloro-
methylamino, di-(chloroethyl)amino, N-ethyl, N-tribromocyclohexyl-
amino, di-(tribromochloroethyl)amino, di-(dichlorobromoisopropyl)-
amino, butadienylamino, di-(fluorocyclopenyl)amino, di(diiodoethyl)-
amino and bis(2,3-dibromopropyl)amino.
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All of the aforedescribed and aforementioned Y and Yl groups
can be attached to the diphosphoryl or dithiophosphoryl pentaery-
thritol group, also characterized as 3,9-substituted-2,4,8,10-tetra-
oxa-3,9-diphosphaspiro [S.~ undecane-3,9-dioxide or disulfide. The
numerical designations used in naming the compounds of this inven-
tion can be ascertained by reference to the following formula
where the members of the heterocyclic rings are numbered.
X 10 11 1 2 X
/~/--CH2~ ~ CH2 ~
g \ o CH2 / 6 ~ CH2 - ~ 3
8 7 5 4
Two representative compounds are 3,9-bis(2,3-dibromopropoxy)-2,4,8,-
10-tetraoxa-3,9-diphosphaspiro ~.~ undecane-3,9-dioxide and 3,9-bis-
(N,N-diethylamino)-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.~ undecane-
3,9-dioxide. Two additional representative compounds are the 3,9-
disulfide analogs of the above two compounds. Additional 3,9-bis-
substituted compounds, formed by placing the aforementioned halo-
' genated oxyaliphatic and oxyalicyclic groups and the optionally
halogenated substituted amino groups on the diphosphoryl and dithio-
phosphoryl pentaerythritol groups, constitute additional examples
of compounds within the scope of this invention. The disulfide
analogs of the foregoing compounds are further examples.
In addition to the 3,9-bis-substituted compounds, an even
larger number of 3,9-substituted compounds where the 3- and 9-
substituents are different from each other are also included within
the scope of this invention. The substituents can be varied to
produce mixed diphosphate esters, mixed diphosphoramidates and
combination phosphate - phosphoramidate compounds. Exemplary
combinations of 3- and 9- substituents include dibromoethoxy and
--8--
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tribromochlorobutoxy; dibromopropoxy and dibromochloroneopentyloxy;
diethylamino and phenylamino; diphenylamino and tribromoethylamino;
di-(bromophenyl)amino and dibromopropoxy; bromoethylamino and di-
bromochlorobutoxy; diethylamino and dibromopropoxy; and unsubsti-
tuted amino and diiodoisopropoxy.
The compounds of the present invention can be prepared by
reacting a 3,9-dihalo-2,4,8,10-tetraoxa-3,9-diphosphaspiro ~S.~ -
undecane-3,9-dioxide or disulfide with an alcohol or an amine to
yield the appropriate diphosphate ester or diphosphoramidate.
The equation for the reaction is:
X X
., 'I`, o--CH2 ~ CH2 0 ~/~
' Hal- P \ C P- Hal + Y- H
`............................\0--CH2 CH2 0
.; J, ~
,' X X
/~ ~0 - CH2~ / CH2 \/~_ y
'~ \0--CH2 CH2 0
where Y has the meaning set forth above in the description of the
compounds and where Hal indicates a halogen atom. As an alterna-
tive reactant for the alcohol or amine, the metal salts of the
alcohol or amine can be used. If it is desired that the two Y
groups be different from each other, two different Y - H reactants
should be employed. The reaction can be carried out by simply
mixing the halophosphate and the alcohol or amine reactants
together and heating the mixture gently for a period of time.
The conditions of reaction will vary widely depending upon the
reactants, but heating the reactants under gentle refluxing
conditions for a period of time of up to three or four hours is
acceptable for preparing many of the compounds of this invention.
_g _
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Catalytic quantities of a metal salt or oxide such as magnesium
oxide, magnesium chloride, calcium oxide, calcium chloride,
titanium chloride or vanadium acetate, or stoichiometric quan-
tities of a weak organic base such as pyridine or triethylamine,
can be used to accelera~e the completion of the reaction. The
halophosphate starting reactant can be prepared by reacting
pentaerythritol with phosphorus oxyhalide.
Compounds of the present invention are useful as flame retar-
dants in polymeric compositions. Polymers applicable to the
present invention can be any of the natural or synthetic polymers.
Naturally occurring polymers include cellulosic polymers such as
cellulose, cellulose acetate and cellulose triacetate, natural
rubber and animal proteinaceous substances such as leather and
casein. Synthetic polymers useful herein include the thermo-
plastic and thermosetting polymers. Examples of suitable polymers
include the polyamides such as nylon 6, nylon 11, nylon 6,6 and
nylon 6,10; the polyolefins such as polyethylene of both the low-
and high-density types, polypropylene and poly(4-methylpentene-1);
acrylic polymers such as poly(acrylonitrile), poly(ethyl acrylate)
and poly(methyl methacrylate); vinyl polymers such as poly(vinyl
chloride) and poly(vinyl acetate); styrene polymers such as
polystyrene including both crystalline and high-impact types,
and styrene copolymers such as po`ly(styrene-butadiene) and
acrylonitrile-butadiene-styrene polymer; acetal polymers such
as poly(formaldehyde); polyesters of both the saturated and un-
saturated variety; polyethers such as polyethylene glycol, poly-
butylene glycol and chlorinated polyethers; polycarbonates; amino
~esins; polysulfones; polyurethanes; silicone polymers such as
polydimethylsiloxane, fluorosilicones and silicone rubbers;
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~ O 5Z02~7
phenolic resins such as phenol-formaldehyde and cresolfurfural
resins; polyphenylene oxides such as poly(2,6-dimethylphenylene
oxide); melamine resins such as melamine-formaldehyde polymer;
epoxy resins such as the reaction product of epichlorohydrin with
bisphenol-A and epoxy novolak polymers and p-aminophenol epoxies;
furane resins such as poly(furfuryl alcohol); allyl resins such
as poly(diallyl phthalate), poly(diallyl isophthalate) and poly-
(diallyl maleate); fluoroplastics such as polytetrafluoroethylene,
poly(chlorotrifluoroethylene), polyvinylidene fluoride and fluori-
nated ethylene-propylene polymers; polybutadiene rubbers; and a
number of specialty resins such as polyethylene ionomers and poly-
allomer copolymers. In addition to the above-mentioned polymer
systems, a much larger number of copolymers and polymer blends
are also included within the scope of the present invention.
Among the many combinations of polymer and flame retardants
within the scope of this invention, there are a number of pre-
ferred combinations. The phosphoramidates and phosphate esters
described herein are particularly useful in polyurethane, poly-
styrenes, polyesters of both the thermosetting and thermoplastic
type, polyolefins, poly(acrylic esters) and acrylonitrile-buta-
diene-styrene copolymers. Of the foregoing polymers, polyure-
thanes and polystyrenes are the polymers most preferred for
modification with the phosphoramidates of this invention. The
phosphate ester flame retardants described hereinabove are
especially useful in acrylonitrile-butadiene-styrene copolymers,
polystyrene and polyesters.
In addition to being among the preferred flame retardants
for polymeric compositions, phosphate esters containing the neo-
pentyloxy moiety are especially desirable flame retardants for
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polyolefins, including, among others, polypropylene, polyethylene
and polypropylene-polyethylene copolymers, polystyrene including
both the crystalline and high-impact types, acrylonitrile-butadiene-
sytrene polymers, polyesters of both the saturated and unsaturated
variety, Including, among others, polybutylene terephthalate, poly-
urethanes, including foamed polyurethane cellulosic polymer, and
cellulosic polymeric polyester blends. Further, 3,9-bis(2,2- Ldi-
bromomethy~ -3-chloropropoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-
~.~ undecane-3,9-dioxide and 3,9-bis(2,2-~ibromomethy~ -3-bromo-
propoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro r5.~ undecane-3,9-
dioxide are excellent flame retardants for polypropylene with 3,9-
bis(2,2- ~dibromomethy~ -3-bromopropoxy)-2,4,8,10-tetraoxa-3,9-
diphosphaspiro C5 ~ undecane-3,9-dioxide also being an excellent
flame retardant for polybutylene terphthalate. `
The flame retardant additives mentioned herein can also be
used in polymers and polymeric compositions which are further modi-
fied through the use of other additives such as fillers, fibers,
pigments, dyes, plasticizers, stabilizers, antioxidants and the
like.
The polymers which are rendered flame retardant through the
use of the flame retardant compounds described herein can be in
` any form or configuration such as fibers, filaments, films, sheets,pellets, powder, foams and finished articles. Polyurethane and
polystyrene foams constitute two of the preferred polymer config-
urations for improvement of flame resistance by the practice of
this invention. The use of the phosphoramidates described above,
particularly the non-halogenated phosphoramidates, with
polyurethane and polystyrene foams constitutes one of the
preferred embodiments of this invention. Use of the phosphor-
-12-
.
1052027
amidates, both halogenated and non-halogenated, with unfoamed
polyurethane and polystyrene, constitutes another particularly
preferred embodiment.
The amount of flame retardant which is used in the composi-
tions and in the methods of this invention is that amount necessary
to produce measurable flame retardancy in the compositions which
are so modified. Depending upon the particular compound and the
particular polymer with which it is combined, the quantity of
flame retardant employed in the compositions and methods of
this invention can be of any amount up to about 50 percent or more
by weight of the total composition. For most compositions, the
flame retardant will comprise from about one to about 25 percent
by weight of the total composition.
In addition to the flame-retardant phosphates and phosphor-
amidates described above, the flame retardancy of a polymer can
be further enhanced through the use of so-called "synergists"
which enhance the flame retardant effectiveness of the phosphates
and phosphoramidates. Effective synergists include certain metal
oxides and salts s-uch as oxides and salts of antimony, arsenic,
bismuth, tin and zinc. Examples of compounds useful herein are
antimony oxide, antimony chloride, antimony bromide, antimony
iodide, antimony oxychloride, arsenic trioxide, arsenic pentoxide,
zinc sulfate, zinc oxide, zinc borate, stannous oxide and the like.
A preferred synergist is antimony oxide. The amount of synergist
can, like the flame retardant phosphates and phosphoramidates
described above, be used in any amount, taking into account the
effect that large amounts of the material may have upon the pro-
perties of the polymeric composition. Customarily, the synergist
can be employed in concentrations as high as 50% by weight of the
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total composition, preferably from about 1 to 15%~ and more prefer-
ably from about 2 to 10%., by weight of the total composition. One
level of synergist which is often used is an amount which is from
about 25 to about 75%~ preferably from about 33 to 67%~ by weight
of the flame retardant phosphates or phosphoramidates described
above.
The flame retardants can be incorporated into the polymer
during the polymerization of the monomeric reactants as long as
care is taken to minimize any adverse side reactions between the
flame retardant and any of the other constituents of the reaction
mixture. Alternatively, the flame retardant can be mixed with
dissolved, powdered or pelleted polymer prior to molding, thereby
providing after molding a finished polymeric article with the
flame retardant intimately mixed throughout. Suitable mixing
` methods include mill rolling and dry mixing in machinery such asa Banbury mixer or the like. Adding flame retardant to a solution
or dispersion of the polymer is also acceptable. A third method
for combining polymer and flame retardant additive comprises a
topical application of the additive to the polymer in its finished
form. As an example, a textile filament, fiber, yarn or the like
can be passed through a solution, suspension or dry powder of the
additive, which is deposited on the polymer as it passes through
the medium containing the flame retardant. Instead of a textile
fiber, the polymer can be in any finished shape as long as it can
somehow be immersed or sprayed or otherwise surface-coated with
the flame retardant medium. To aid the polymer in picking up a .
sufficient quantity of the flame retardant, the surface of the
polymer can be pre-treated with a substance which will render the
polymer more receptive to the flame retardant. After the topical
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lOSZOZ7
application, the polymeric article can be subjected to a post-
treatment which results in the flame retardant additive being
firmly adhered to the surface of the polymer. Suitable post-
treatments can include the application of heat, pressure or both
to the polymeric article, or a subsequent coating of the flame
retardant-treated article with a binder to adhere the flame
retardant firmly to the polymer.
The following examples are provided for the purpose of further
illustration only and are not intended to be limitations on the dis-
closed invention. Unless otherwise specified, all temperatures are
expressed in degrees centigrade; all weights are expressed in grams;
and all volumes are expressed in millimeters.
Example 1
A quantity of 29.7 grams of 3,9-dichloro-2,4,8,10-tetraoxa-
3,9-diphosphaspiro [5.5] undecane-3,9-dioxide, 43.6 grams of 2,3-
dibromopropanol and 0.1 gram of magnesium oxide were mixed
together and heated to 110C. to drive off the hydrogen chloride
as it evolved. Hydrogen chloride evolution stopped after about
two hours, at which time the reaction mixture was permitted to
cool to room temperature. The resultant viscous product was
washed with ammonium hydroxide at 60C. and then with water.
The light brown viscous liquid was dried under vacuum. Percent
bromine c~lculated for 3,9-bis(2,3-dibromopropoxy)-2,4,8,10-
tetraoxa-3,9-diphosphaspiro ~.~ undecane-3,9-dioxide is 48.5%.
Percent bromine found by elemental analysis was 47.7%.
Example 2
Dibromopentaerythritol cyclic chlorophosphite,
-15-
105Z027
BrCH2 CH2 \
C PCl
BrCH2 2
was prepared by reacting dibromopentaerythritol with a slight
molar excess of phosphorus trichloride.
The above chlorophosphite, 380 grams, was then reacted with
a slight molar excess of gaseous chlorine, 95 grams, in the pres-
ence of 200 ml. of methylene dichloride. An ice bath was used
during the chlorine addition to hold the reaction temperature to
25 to 30C. After the chlorine addition was complete, the
methylene dichloride was evaporated, leaving the product, 2,2-di-
(bromomethyl)-3-chloropropyl dichlorophosphate, '
CH2Br ~ / Cl
ClCH2 - C - CH 0 P
CH2Br
A quantity of 279 grams (0.7 mole) of the above dichloro-
phosphate was mixed with 47.7 grams (0.35 mole) of pentaerythritol
in the presence of 300 ml. of toluene and 0.5 gram of magnesium
oxide. The reaction mixture was heated to reflux temperature to
remove hydrogen chloride. ~fter about 12 hours at reflux tempera- - ;
'` ture, the mixture was allowed to cool and was subjected to vacuum
to remove additional hydrogen chloride. The white precipitate was ~-
filtered and washed once with ammonium hydroxide and twice with -~ `
water, and then crystallized from methanol. The produce was
identified as 3,9-bis(2,2-di-bromomethyl-3-chloropropoxy)-2,4,8,10-
tetraoxa-3,9-diphosphaspiro ~.~ undecane-3,9-dioxide. Melting
point was 212C. Calculated halogen content is Br, 40.7%; Cl,
8.93%; found Br, 41.1%; Cl, 9.12%.
-16-
:
,;
105ZOZ7
Example 3
To a suspension of 29.7 grams (0.1 mole) of 3,9-dichloro-
2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.~ undecane-3,9-dioxide in
250 ml. of benzene was added 30 grams of diethylamine in 50 ml.
of benzene. The mixture was heated to reflux temperature for
three hours and then filtered to remove the precipitated amine
hydrochloride. Upon evaporation of the benzene, a clear oil
remained which crystallized upon cooling, and was subsequently
recrystallized from water.- Melting point of the white crystalline
product was 189.5 to 190.5C. Calculated elemental analysis for
3,9-bis(N,N-diethylamino)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-
[5.5~ undecane-3,9-dioxide was C, 42.2%; H, 7.6%; N, 7.6%. Found
C, 41.1%; H, 7.5%; N, 7.2%.
Example 4
To 122 grams of the chlorophosphate of Example 3 in 800 ml.
of toluene was added 146 grams of p-bromoaniline and 82 grams of
triethylamine. The mixture was heated to 95C. for four hours
and then allowed to cool. Two layers formed and the toluene was
decanted. The product layer was washed with 800 ml. of water and
then with boiling acetone to yield`a white solid with a melting
point of 276 to 278C. Bromine content calculated for 3,9-bis-
(N-p-bromophenylamino)-2,4,8,10-tetraoxa-3,9-diphosphaspiro ~
undecane-3,9-dioxide was 28.2%. Bromine content found was 30.0%.
Example 5
Preparation of 3,9-his(2,2- ~imethy~ -3-chloropropoxy)-2,4,-
8,10-tetraoxa-3,9-diphosphaspiro [5.5]undecane-3,9-dioxide.
A quantity of 2,2-dimethyl-3-chloropropyl dichlorophosphate
(748.2 gm; 3 moles) was dissolved in 800 ml. of toluene. To the
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. _ . . .. _ . . . . _ _ . . . _ _
10520Z7
above was added 209 gm (1.5 moles) of pentaerythritol and 3 gm of
magnesium oxide. The solution was refluxed at 110C. for 9 hours.
The mixture was filtered leaving a white solid. This material was
washed with 1 liter of acetone, followed by a wash with an aqueous
ammonia solution having a pH of from about 8 to about 9. This
solution was filtered and washed with 2 liters of water followed
by a final acetone wash of 1 liter. The material was dried in a
forced air oven at 105C. for 3-1/2 hours. About 442 gm of
material was recovered giving a yield of about 63%. The melting
point of the compound was determined to be 282 to 285C.
Example 6
Preparation of 3,9-bis(2,2- [dibromomethy~ -3-bromopropoxy)-
2~4,8,10-tetraoxa-3,9-diphosphaspiro [5.~ undecane-3,9-dioxide.
A quantity of phosphoryl chloride (50 gm) and 0.4 gm of
magnesium oxide were heated to 85C. Tribormoneopentyl alcohol
(300 gm; 0.924 moles) was added in increments over a 1.25 hour
period. The reaction continued at a temperature of 85C. for 6
hours. The excess phosphoryl chloride was distilled under an
aspirator vacuum to a pot temperature of 130C. The reaction
was cooled to 100C. and 0.462 mole (62.8 gm) of pentaerythritol
and 300 ml of toluene were added. Additional toluene was added
as needed. The system was refluxed for 6-1/2 hours, cooled to
room temperature, filtered, and dried at 100C. in a vented oven.
The residue was washed with about 1 liter of water. An
aqueous ammonia solution was added to give a pH of about 8. The
residue was then washed with water and then with acetone and
finally dried at 100C. in air vented oven. Yield: 335 gm (83%);
Melting point: 225 to 228C.
-18-
'. '
10520Z7
Exam~le 7
Preparation of 3,9-bis(2,2- [dichloromethy~ -3-chloropropoxy)-
2,4,8,10-tetraoxa-3,9-diphosphaspiro L5.~ undecane-3,9-dioxide.
About 1 mole of 2,2-dichloromethyl-3-chloropropyl dichloro-
phosphate was placed into a 3 liter flask. To this was added 1 gm
of magnesium oxide, 2 liters of toluene, and 0.5 mole of pentaery-
thritol. The reaction was stirred and heated at reflux until the
; acid number was less than 10. The toluene was stripped off and
the solid portion was placed in an oven and dried without being
washed. The product was ground up after having been dried for 4
hours at 110C. and washed with a 50/50 acetone/water solution.
, The resulting product had a melting point of 197 to 200C. and
j the melt remained clear until decomposition was reached at 270to
280C.
. Example 8
The following compounds were synthesized:
O O
CH3CH2CH20 P\ . X ~ P--OCH2CH2 CH3, (here ina fter
referred to as "A"),
O O
1`/ \ / \l`
F 0 / P - OCH2CH2CH2Cl, (hereinafter
` 20referred to as "B"),
.
f ~ ~, , f Ic 3
BrCH2 -CH - 0 - P \ ~ / P - 0 - CH - CH2Br, (hereinafter
referred to as "C"),
-19-
_, :
'
10520Z7
~î~ -~ r 1`
BrCH2CHBrCH20-- p ~ / P - OCH2CHBrCH2Br, (hereinafter
referred to as "D"), and
CH2Br o ICH2Br
ClCH2_ f - cH2o_p, ~ ~P-_OCH2 f CH2Cl, (here-
CH2Br CH2Br
-, inafter referred to as "E").
.
Compound D above was synthesized according to Example 1,
supra. Compound E above was synthesized according to Example 2,
supra. Compounds A, B, and C above were syntheiszed by the
general method disclosed in Example 3 of U.S. Patent 3,090,799
(hereinafter referred to as Wahl et al.) and said compounds were
identified by nuclear magnetic resonance (NMR) spectroscopy and
- were found by said technique to have a purity of greater than 95%.
, Compounds A, B, C and D above are representative of compounds
., outside the invention as claimed herein but within the scope of
Wahl et al. Compound E is representative of the pentaerythritol
cyclic diphosphates of the presently claimed invention.
.
Example 9
The hydrolytic stability of the above synthesized compounds
of Example 8 were determined by the following procedure: A mag-
netically stirred emulsion containing 4 grams of Compounds A, B,
C, D, or E, above, 1 gram of Emcol AM2-lOC emulsifier (Emcol AM2-
lOC emulsifier is a mixture of free acid of phosphated nonionic
plus nonionic; Emcol AM2-lOC is a trademark of Witco Chemical
-20-
lOSZOZ7
Corporation, New York, New York), and 45 grams of water was heated
at lOO~C. for 44 hours. The acid number of the emulsion was then
determined by titration with a standard potassium hydroxide solu-
tion and the results are tabulated in Table II, infra.
TABLE II
Hydrolytic Stability Tests
.
Acid #
Compound (m~KOHt~ Sample) Compound/E x 100%( )
A 21.6 911
B 19.3 814
C 23.4 987
D 9.45 399
E 2.37 ---
(1) Percent decrease in hydrolytic stability of
prior art compound when compared to the
pentaerythritol cyclic disphosphates of the
presently claimed invention as represented
by Compound E.
A compound's acid number is inversely proportional to the
hydrolytic stability of that compound, i.e., the larger a com-
pound's acid number, the poorer will be said compound's hydro-
lytic stability.
Example 10
The thermal stability of compounds A, B, C, D, and E, above,
as well as 3,9-bis(2,2- ~imethy~ -3-chloropropoxy)-2,4,8,10-tetra-
oxa-3,9-diphosphaspiro ~.5] undecane-3,9-dioxide (prepared in
Example 5, supra, and hereinafter referred to as "F"), 3,9-bis-
(2,2-~ibromomethy~ -3-bromopropoxy)-2,4,8,10-tetraoxa-3,9-diphos-
phaspiro ~.~ undecane-3,9-dioxide (prepared in Example 6, supra,
and hereinafter referred to as "G")? and 3,9-bis(2,2- [dichloro-
-21-
lOSZOZ7
methy~ -3-chloropropoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-
~5.~ undecane-3,9-dioxide (prepared in Example 7, supra, and
hereinafter referred to as "H") was determined by the procedure
set forth in Section 9-951, "Thermogravimetric Analyzer", of
"Instruction Manual 990, Thermal Analyzer and Modules", E. I.
Du Pont De Nemours and Co. (Inc.), Instrument Products Division,
Wilmington, Delaware 19898. The results of the thermogravi-
metric analyses (TGA) of the eight compounds at several different
weight losses are tabulated in Table III below:
., .
c~
. O
u~
~' ~
t~ o 1~ oo o o
. ~ X I ~ ~ ~ ,_
.~ o c~J
~ o o ~ u~ u~
.~ c C~l o o~ ~ ~ u,
: ~ ~ ~ ~ ~ ~ .
:; ~)
'1 O ~ U~
~ ~ ~ 1 '--
.;, ~ c~
: ~
~ oo ~ O
:3 ~ I ~ u~
C"l C~l N ~) ~
rl O O ~ ~ O ~'
. ~1 ~`I
I ~ ~ C~
,~tU O LO00 0 0
~1 ~_ ~~1 U) I~
cl~O ~1C~
,: ~ J- O ~ ~ C`l O
~1 ~` ~
5-1 ~ -1C~ C`J
E~
~ Ir~ o 00 u~
.` ¢l ~ ~),~
.,' U~
.' O
,~ ~a o o o
oo
c ~ o u~ o
H
-22-
. - .
I
10520Z7
Table III clearly indicates that compounds E, F, G, and H
have unobviously superior thermal stability when compared to close
prior art compounds.
The superior thermal and hydrolytic stability of the com-
pounds within the scope of the invention as claimed has signifi-
cant commercial implications. The superior hydrolytic stability
of the compounds within the above narrow subgroup enables said
compounds to be superior flame retardants when applied via an
; aqueous system because the surrounding aqueous environment would
not cause said compounds to break apart as readily as would the
close prior art compounds of Wahl et al.; for the same reasons,
the compounds within the narrow subgroup are also superior flame
retardants for incorporation into articles of manufacture which
have a contemplated use wherein said articles would be subject to
exposure to moisture.
The superior thermal stability of the compounds within the
above narrow subgroup enables said compounds to be processed
without significant weight losses at temperatures wherein close
prior art compounds within Wahl et al. exhibit substantial weight
losses such that said prior art compounds are not commercially
capable of being used. For example, polypropylene is typically
processed at 204C. and molded at 232C. Since compounds A, B,
C and D lose at least 10% of their weight before the molding
temperature of polypropylene, these materials cannot be used
effectively as flame retardants for polypropylene. In contrast,
compounds E and G possess excellent thermal stability and are
effective flame retardants for polypropylene as the following
Example 11 indicates.
23
- ~05Z027
Example 11
The flame retardant and Pro-fax~i~) 6823 polypropylene base
resin was compounded using a C. W. Brabender Prep-Center fitted
with a high shear compounding mixer. (Pro-fax 6823 is a trade
mark of Hercules Incorporated, 910 Market Street, Wilmington,
Delaware 19899.) The flame retardant additive was dry blended
with the polypropylene. Since the capacity of the mixing bowl was
`~ only 300 grams, a dip technique for compounding was utilized which
consisted of fluxing 300 grams of the dry blend mixture and the
removal of approximately 200 grams of the fluxed mixture followed
by the addition of more of the dry blend mixture until the total
dry blend had been compounded. Each charge was compounded under
the same conditions: 400F. temperature, 120 rmp, with 2 to 3
minute compounding time.
Each flame retarded system was then let down to the desired
level by dry blending the ground concentrate and the base resin.
The base resin and flame retarded systems were injection molded
using a Newbury 30 Ton Injection Molding machine. The following
` is a set of standard injection molding conditions by which all of
the systems were injection molded.
Rear Zone 410F.
~ Front Zone 440F.
', ~ Nozzle 60F.
Injection Speed 4 to 5 seconds
Cycle Time 60 seconds
Mold Temperature ~ 30C.
Flow Mold Time 1 to 2 seconds
The above prepared resins were subjected to various tests and the
data derived from said tests are reported in Table IV, infra.
-24-
lOSZOZ~7
TABLE IV
Flame Retardant Testin~
in Pro-fax 823 PolYpropylene
FlameRetardant Level F.R. (phr) O.I.(2) UL-94(1)
None --- 17.0 HB
E 12.5 25.5 V-O
E 15.0 23.5 V-O
G 9.0 26.5 V-O
G 12.5 27.5 V-O
G 18.0 24.0 V-O
( )UL-94 Flammability Test at a specimen thickness
of 1/8 inch, Underwriters' Laboratories, Inc.
( )Oxygen Index, ASTM D-2863-70.
;
` The difference in thermal stability is not obvious and is
the difference between a material which can be used effectively,
as the above Example 11 clearly demonstrates, and one which cannot
be effectively used because of poor thermal stability ln molding
and other processing procedures requiring the expasure of said
material to elevated temperatures.
Example 12
The following compounds were synthesized:
R \11 /C2H5
P N (hereinafter referred to as "X"),
R - / 2 5
.
O
R - O ~ 11 / CH3
P - N \ (hereinafter referred to as "Y"),
R O CH3
.
-25-
-
,
1052027
o o
C2H5~ 11,--\ ~\11 ~C2~5
N P \ ~ P - N (hereinafter referred
C H / 0 / \ - ~ / C2H5
to as "Z"),
as well as compounds A (see Example 8) and D (see Example 8).
Each R above is independently selected from the group containing
80% l-bromo-2-propyl and 20% 2-bromopropyl. Compounds A and D
were synthesized as noted in Example 8. Compound Z was synthe-
sized according to Example 3 and was found to have 41.1% carbon,
7.5% hydrogen, and 7.2% nitrogen by elemental analysis (calculated
content is 42.4% carbon, 7.6% hydrogen, and 7.6% nitrogen).
Compounds X and Y were synthesized as follows: To a mixture
of 61.3 weight parts of phosphoryl chloride and 0.1 weight parts
of anhydrous magnesium oxide was added 111.3 weight parts of bromo-
propanol mixture consisting of l-bromo-2-propanol (80%) and 2-
bromopropanol (20.0%) over a two hour period. The mixture was
heated gradually to 80 to 85C. and held at that temperature for
six hours until no further hydrogen chloride evolution was observed.
This bis(bromopropyl)chlorophosphate product was used in the
following procedures without further purification.
Synthesis of Compound X: Bis(bromopropyl)chlorophosphate
(256 grams) was dissolved in 750 ml of methylene chloride and L04
grams of diethylamine was added dropwise with mechanical stirring
while keeping the temperature of the solution below 30C. After
stirring at room temperature for one hour, the solution was ex-
tracted with water, dilute hydrochloric acid, and water, and then
dried over magnesium sulfate. The methylene chloride was evapor-
ated off. Yield: 218 grams; calculated bromine content: 40.5%;
bromine content found by elemental analysis was 38.53%; acid number
found was 1.61.
-26-
_- .
105Z027
Synthesis of Compound Y: Bis(bromopropyl)chloroPhosphate
(305 grams) was dissolved in 300 ml of benzene and 80 grams of
dimethyl amine was added dropwise with cooling over a two-hour
period. The reaction mixture was stirred at room temPerature
for three hours and the precipitated dimethyl amine hydrochloride
was filtered off. The benzene was evaporated. The product was
washed three times with 300 ml of water and dried at 80C. per
mlnute for one half hour. Yield: 145 grams; calculated bromine
content is 43.5%; bromine content found by elemental analysis was
4~.21%.
Compounds X and Y are representative of compounds having
` amino substituents similar to those disclosed in U.S. Patent
3,810,838 (hereinafter referred to as Haugen), U.S. Patent
. 3,584,085 (hereinafter referred to as Hartman) and U.S. Patent
3,645,971 (hereinafter referred to as Hindersinn) yet outside
the scope of those references but said substituents being struc-
, turally closer to the amino substituents of the pentaerythritol
, cyclic diphosphoramidate of this invention. Compounds A, supra,
and D, supra, are representative of compounds within the scope
of Wahl et al.
.
Example 13
`~ The thermal stability of compounds A, D, X, Y and Z
` prepared above, was determined by the same procedure set forth
in Example 10. The results of the thermogravimetric analyses~i
(TGA) of the five compounds at several different weight losses
are tabulated in Table V.
-27-
10520Z7
TABLE V
TGA Results
Temperature at which
Wei~ht Chan~e Occurs, C.
Compound A D X Y Z
Initial Weight Loss 45 100 35 110 239
5% Weight Loss 130180 72 142 245
10% Weight Loss 158204 110 147 252
25% Weight Loss 225224 183 174 269
50% Weight Loss 347260 215 195 296
Table V clearly indicates that Compound Z has unobviously
superior thermal stability than would be predicted from the
thermal stability of prior art compounds.
The superior thermal stability of Compound Z and compounds
within the scope of the pentaerythritol cyclic diphosphoramidates
of this invention has significant implications. The superior
! thermal stability of the compounds within the above narrow subgroup
enables said compounds to be processed into polymeric compositions
without significant weight losses at temperatures wherein the
prior art compounds within Wahl et al.,Hartman, and Hindersinn
exhibit substantial weight losses such that said prior art com-
pounds are not commercially capable of being used and therefore
- not commercially practical flame retardants for such polymeric
compositions.
Example 14
To 150 grams of a general purpose unsaturated polyester
prepolymer (Koppers 1010-5) was added 9.6 grams of antimony oxide,
40.2 grams of 3,9-bis(2,2-dibromomethyl-3-chloropropoxy)-2,4,8,10-
-28-
1052027
tetraoxa-3,9-diphosphaspiro ~.~ undecane-3,9-dioxide, 0.5 grams of
cobalt naphthenate and 1 gram of methyl ethyl ketone peroxide.
The resultant mixture was poured over three layers of random glass
mat and allowed to cure at room temperature. The polyester-glass
laminate produced thereby contained a total of 24% by weight glass
fiber. The amount of the diphosphate ester of pentaerythritol was
27 parts per hundred parts of resin. The antimony oxide present
was equal to 6.4 parts per hundred parts of resin.
The composition was tested to measure its flame retardancy
and the test results were compared with flame retardancy measure-
ments made on the same polyester without the flame retardant
additive and antimony oxide. For further comparative purDoses,
the flame retardancy of the same polyester modified with 10 parts
per 100 parts of resin of a commercially available flame retardant
commonly used with polyesters, tris(2,3-dibromopropyl)phosphate,
is also measured~ Results are reported in Table VI below.
`
Example 15
! To 209 grams of the same polyester prepolymer used in
Example 14 was added 21 grams of 3,9-bis(N,N-diethylamino)-2,4,8,-
10-tetraoxa-3,9-diphosphaspiro ~.~ undecane-3,9-dioxide, 0.5 grams
of cobalt naphthenate and 1 gram of methyl ethyl ketone peroxide. " !
A glass fiber laminate was prepared as in ExampleL4 to pro~ide a
polymeric composition containing 22% by weight glass fiber. The
flame retardant additive was present in a concentration of 10
parts per hundred parts of resin.
The composition was tested to measure its flame retardancy
and the test results are reported in Table VI below.
-29-
105ZOZ~7
Example__16
To 217 grams of a 10~/o bromine-containing unsaturated polyester
prepolymer based upon tetrabromophthalic anhydride was added 13
grams of 3,9-bis(N,N-diethylamino)-2,4,8,10-tetraoxa-3,9-diphos-
phaspiro ~.~ undecane-3,9-dioxide, 0.5 gram of cobalt naphthenate
and 1 gram of methyl ethyl ketone peroxide. A glass fiber laminate
was prepared as in Example 14 to provide a polymeric composition
containing 23% by weight glass fiber. The flame retardant additive
was present in a concentration of six parts per hundred parts of
resin. The composition was tested to measure its flame retardancy
and the test results were compared with flame retardancy measure-
ments made on the same polyester without the flame retardant addi-
tive. Results are reported in Table VI below.
The Oxygen Index reported a`bove is a test designed to measure
the percentage of oxygen in an atmosphere necessary to support com-
bustion of the material being tested. Generally speaking, a
material with an Oxygen Index of 21.0 is considered flammable under
ordinary conditions whereas a material with a higher Oxygen Index
possesses some degree of flame retardancy. The procedure for con-
ducting the Oxygen Index test is reported in ASTM D-2863-70.
The test designated "HLT-15" is a flammability test devel-
oped by Hooker Chemical Corporation to measure the flammability
of a specimen suspended in a vertical position and exposed to a
flame for increasing increments of time. The degree of flamma-
bility is measured on a scale of 100 units with 0 indicating the
most flame retardant condition measurable. The procedure for the
HLT-15 test is reported by A. J. Hammerl, "Burning Tests for
Thermosetting Resins", 17th SPI, Reinforced Plastics Division,
Section 12H, pages 1 to 6, February 1962.
-30-
.
lOSZOZ7
The data in Table VI show that the compounds described
herein are capable of producing measurable flame retardancy in
polyester resins. And not only is the flame retardancy measur-
able, but the level of flame retardancy is sufficient to be of
significant commercial interest. The significance of the flame
retardancy attained by polyester compositions with in the scope
of this invention can be recognized by comparing their flame
retardancy values of the same polyester resins modified with
tris(2,3-dibromopropyl)phosphate, a widely used commercially
available flame retardant for polyesters.
Example 17
To 90 parts by weight of crystalline polystyrene (Union
Carbide SMD-3500) was added 10 parts of 3,9-bis(2,3-dibromo-
propoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro ~.~ undecane-3,9-
dioxide and the resultant mixture mixed in a Brabender mixer and
subsequently compression molded at 400F. for five minutes at ;
578 psi followed by a temperature decreasing from 400F. to 200F.
over a ten minute period. The finished composition contained 10%
by weight of the flame retardant additive. The composition was
testèd to measure its flame retardancy and the test results com-
pared with flame retardancy measurements on unmodified polystyrene
and on polystyrene to which tris(2,3-dibromopropyl)phosphate had
been added. Results are reported in Table VII below.
-31-
105ZOZ7
U~
l ~ O O ~ ~ `D
,1 u~
~I x o o u~ n O
o~ a~
~ ~ ~ ~ O~ ~ ~ ~D I
X C C~C~l ~ C`~ ~ C`l
O H "
,C
~n .~
u~ a) ~ c~
t~ 3
J 0
~ ~1
SJ ~ ~
aJ ~D O O O O O O
, C
: ~ C
V~ Q . I
C
~ C)
.. ,~ a~
C ~
`....... H ~ C
h I~ O O O ~O O
. ~ ~, ~1 ,~, .
~ ~; O
r~
CL
O ~
O rC I ~C I rC
h O ~ O O ~ O GJ Cl
r( O rl O ~ rl O C~ O
J l ~ --~ ~3C ~ h rC ~ 5-1 C rC
C I C I ~ P G I -~ p ~. C~
t~ c~ Z ,1 u~ z ,1 u~ rl
~d ^ I .IJ ^ O ~a o ~ o ~ o
a) h ~ ~) a~ Z J~ I rC Z ~ I ~C
G~ --' I I --' a~ ~ ~ --~ a.
_~ a~ ~rl ~ X rl ~ C~l ~ '-1 ~ ~ ~I t~
1-4 P~; E-~ ~ h O .0 0 `-- ~ ,0 0
C ~I C ~ m c~ I C ~ ~ ~ ~
~1 0 ~-~ C r~ O o~ rl O X
^ aJ h ^ ~3 0 h h ^ E~ O h h O
c~ z ~ Cl. ~) ~IS Z ~,
a~
JJ
- h h ~1 1-1 0 ~a) ~1 aJ ~ O
u~ oC u~ C o~ C ~n oo
;. C) h O O h O a~ ~ O O h O O rl ~ ~1 0 ~1
0 ~ C 5-1 H C h ~C h ~I C 5-1 ~1 0 ~ O ~ O ~
P~ E~ O :~ O a) ::~ oO ~ o a~ ~ os~ o h 0 5-1 0 C`l
;. C~
~1 h CJ
.~ a)
E~ rO ~J u~
X
Z
-32 -
lOSZ027
TABLE VII
Flame
Example PolymerFlame Retardant~ Oxy~en
Number Type Retardant % wei~ht Index
17 Polystyrene 2,3-dibromo- 10 26.5
propoxy-etc.~;
; Polystyrene None 0 18.5
Polystyrene tris(2,3-di- 10 28.5
bromopropyl)-
phosphate
* etc. = 2~4~8,10-tetraoxa-3,9-diphosphaspiro-
l5.5~ undecane-3,9-dioxide.
- Example 18
. . .
To 100 grams of a polyoxypropylene triol having an average
molecular weight of 3000 was added 10 grams of 3,9-bis(N,N-diethyl-
amino)-2,4,8,10-tetraoxa-3,9-diphosphaspiro ~.~ undecane-3,9-
` dioxide as a flame retardant, one gram of a block copolymer of
dimethyl siloxane and an alkylene oxide (Union Carbide L-5403 as
a surfactant, 0.35 gram of triethylene diamine (Dabco 33-LV) as a
catalyst, 0.23 gram of stannous 2-ethylhexanoate as a catalyst
.,.,j .
`` and 30 grams of deionized water as a blowing agent. The ingred-
; ients were mixed until an even dispersion was obtained, at which
time 38.1 grams of an 80/20 blend of 2,4- and 2,6-toluene-
` diisocyanate was added with rapid mixing for a few seconds and
then transferred to a mold where the foam was allowed to form.
The foamed polyurethane product was cured at 100C. for 15 minutes.
.:~
A control composition containing all of the above ingredients
except the flame retardant was prepared in a manner identical to
the above preparation.
The compositions were tested for flame retardancy by
measuring their Oxygen Indexes. Results are reported in Table
VIII below.
-33-
10520Z7
Example 19
Three polyurethane compositions were prepared using the
procedure of Example 18 except that instead of 10 grams of the
flame retardant specified in Example 18, quantities of 10, 20
and 30 grams of 3,9-bis(N-p-bromophenylamino)-2,4,8,10-tetraoxa-
3,9-diphosphaspiro [5.~ undecane-3,9-dioxide were used to prepare
the compositions. For comparative purposes three additional poly-
urethane composi~ions were prepared using, instead of the flame
retardant specified above, the same quantities of a commercially
available flame retardant customarily used in polyurethanes,
tris(2,3 -dibromopropyl)phosphate. Results are reported in
Table VIII below.
A study of the data presented in Table VIII shows that the
effectiveness of the flame retardants of both Examples 18 and 19
at the low level of 10 parts per 100 parts of polyol is noteworthy,
particularly since the flame retardancy is achieved with a bromine
concentration which is, in the case of Example 18, non-existent
and in the case of Example 19, is far less than the bromine content
of tris(2,3 -dibromopropyl)phosphate-modified polyurethanes.
Based on this disclosure, many other modifications and
ramifications will naturally suggest themselves to those skilled
in the art. These are intended tobe comprehended as within the
scope of this invention.
-34-
~OS20Z7
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-35 -
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