Note: Descriptions are shown in the official language in which they were submitted.
1~91~
\
This invention relates to polymeric compositions,
more particularly to synthetic resins comprising a polyolefin
polymer and a flame retarding amount of a 3,9-bromophenoxy-
2,4,8,10-tetraoxa-3,9-diphosphaspiro(5.5)undecane-3,9-
dichalcogen compound.
U~S. Patent 3,090,799 (hereinafter referred to as
Wahl et al), discloses plasticizers comprising phosphoric
acid esters of the generic formula:
O O
R10--P~ X / --OR2
in which Rl and R2 represent aliphatic, cycloaliphatic,
heterocyclic or aromatic radicals, the hydrogen atoms of
which can be substituted, for example, by halogen, ester, keto,
nitrile, or amino groups. Rl and R2 can be identical or
different. Because of the relatively high phosphoric acid
content of the above compounds of Wahl et al, said compounds
are stated by Wahl et al to impart a greater reduction in the
combustibility for the same addition of plasticizer, in
other words, smaller additions of Wahl et al's compounds are
sufficient for producing the same effect.
The plasticizers of Wahl et al are stated as
being useful in the production of shaped plastic compositions,
such as foils, fiber and lacquer materials, as well as mold-
ing materials, from organic compounds of high molecular weight,
such as cellulose esters, cellulose ethers, polyvinyl com-
pounds, for example, polyvinyl chloride, polyvinyl acetate,
polystyrene, chlorinated rubber, alkyl resins, polyesters,
polymers of acrylic acid and derivatives thereof, polyethylene
polypropylene and other polymers and copolymers. Wahl et al
further state that their phosphoric acid ester compounds may
-- 1 --
be used in any suitable thermoplastic resin.
The above discussion by Wahl et al is very generic
and merely restates a general principle which is well known in
the art of ~lame retardants, i.e., that phosphorus is capable
when present in particular compounds of imparting flame `
retardant efficacy to materials treated therewith. However,
it is also well known in the flame retardant art that there
presently does not exist a universal flame retardant capable
of imparting effective flame retardancy to all polymeric
materials. Practitioners in the flame retardant art well
recognize that although a compound may be an effective flame
retardant for one polymer system, the same material may be
ineffective for another. A flame retardant art practitiOner
also knows that it takes inventive skill to determine what
particular compound is capable of imparting flame retardant
efficacy to a particular polymer system.
It has been discovered that a limited class of 3,9-
halophenoxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro(5.5)undecane-
3,9-dichalcogen compounds impart an unusual high level of
flame retardant efficacy to polyolefin polymers.
According to the present invention there is provided
a polymeric composition comprising a polyole~in polymer and a
flame retarding amount of a compound of the formula (I):
Brm X X
~ 0 ~ ~ I (I)
wherein each X is identical and either oxygen or sulfur, pre-
ferably oxygen, each m is an integer from 1 to 5, preferably
from 1 to 4, and more preferably 3, n is an integer from 1 to
5, preferably from 1 to 4, and more preferably 3, I~ is also
preferred that n equals m' it is thus especially preferred
li~91~ ,
that m and n are both 3, whereby m plus n is 6. Further, it is
preferred that both bromophenoxy groups be the same. Prefer-
ably the compound contains at least ~5% by weight of bromine.
In another aspect of the invention there is provided
a method of rendering a polyolefin polymer flame retardant
which comprises incorporating a flame retarding amount of a
compound of formula (I~ therein.
For purposes of illustration only, Table I, which
follows is designated to further help describe the flame
retardants of this invention and is neither meant nor should
it be taken to be a complete listing of all the compounds
within the scope of formula (I).
The numerical designations used in naming the
compounds of this invention can be ascertained by reference
to the following formula where the mem~ers of the hetero-
cyclic and phenoxy rings are numbered.
~ O- Pg~ O _ ~ O~ 3- 0 ~ 4
r~
1~()917~i
~mmmmmmm
~ h
~llmmmmm
h ~ h S~ h
m ~mmmmmmm
I I I I s~
~Illlmmm
- ~ h S~ ~
H ~ mmmmmmm
- ~ S l h h h
~mmmmmmm
mmmmm
. . - S~ h ~ h 5~ h S~
~mmmmmmm
:~
i I t I I ~ ~
~Illllmm
-
~mmmmmmm
X I O U~ O U~ O O U~
o
C)
- 4 -
11~91~6
The preferred compound within the scope o~ formula
(I) is 3,9-bis(2',4',6'-tribromophenoxy)-2,4,8,10-tetraoxa-
3,9-diphosphaspiro(5.5)undecane-3,9-dioxide.
In addition to the 3,9-bis-substituted compounds, an
even larger number of 3,9-substituted compounds were the 3,9-
substituents are different from each other are also included
within the scope of this invention,
The compounds of the present invention can be pre-
pared by reacting a 3,9-dihalo-2,4,8,10-tetraoxa-3,9-diphos-
phaspiro(5.5)-undecane-3,9-dioxide or disulfide with sub-
stituted halophenols to yield the appropriate diphosphate ~-
ester. The general reaction scheme is illustrated as follows:
Hal- P\ X /~ - Hal + ~ OU
~O-P~O~/\P-O-~ ~
wherein X has the meaning set forth above and wherein
Hal indicates a halogen atom and Y is 1 to 5 bromo atoms. As
an alternative reactant for the halophenol, the metal salts of
the halophenol can be used. If it is desired that the two
halophenol groups be different from each other, two different
halophenol reactants should be employed. The reaction can be
carried out by simply mixing the halophosphate and the halo-
phenol or halophenol metal salt reactants together and heating
the mixture gently at a temperature of 30 to 160C. for a
period of time of from 1 to 12 hours. The above reaction can
be conducted in the presence or absence of inert solvents.
Suitable inert solvents include aromatic solvents, e.g., benzene
toluene, etc., and dipolar aprotic solvents, e.g., dimethyl~
-- 5 --
9176
formamide, dimethylsulfoxide, acetonitrile, and the iike.
Catalytic quantities of a metal salt or oxide such
as magnesium oxide, magnesium chloride, calcium oxide,
calcium chloride, titanium chloride, or vanadium acetate,
or stochiometric quantities of a weak organic base such as
pyridine or triethylamine, can be used to accelerate the
completion of the reaction. The halophosphate starting
reactant can be prepared by reacting pentaerythritol with
a phosphorus oxyhalide.
The compounds within the scope of this invention can
also be prepared according to the following reaction scheme:
~ OH + PXCl~ ~ OPC12
Reaction A Il
2 II + C(CHzH)4--~ ~ \ o X O
-Reaction B
wherein Y and X are as defined above. As an alternative
reactant for the halophenol, the metal salts of the halo-
phenol can be used. If it is desired that the two halophenol
groups be different from each other, two different halophenol
reactants should be employed. Reaction A can be carried out
by refluxing the halophenol or halophenol metal salt with an
e~cess amount of either phosphorous oxychloride or phosphorous
thiochloride for a period of 1 to 48 hours, Catalytic
quantities of a metal salt such as potassium chloride, sodium
chloride, etc., or stochiometric quantities of a weak organic
base such as pyridine or triethylamine, can be used to
accelerate the completion of the reaction.
J - 6 -
1~9~'76
To conduct Reaction B, two moles of the crude halo-
phenyl dichlorophosphate or dichlorothiophosphate, II, are
suspended or dissolved in an inert solvent. Suitable inert
solvents include aromatic solvents, e.g., benzene, toluene,
etc., and dipolar aprotic solvents, e.g., dimethylformamide,
dimethylsulfoxide, acetonitrile, etc. One mole o~ penta-
erythritol is added and the reactants are heated at 80 to
140C. for a period of 1 to 10 hours. The final product is
separated by filtration, purified by standard techniques
well known to those skilled in the art, e.g., washing,
recrystallization, etc., and dried.
The flame retardants within the scope of this
invention as well as mixtures thereof display an unobvious
level of flame retardant efficacy in polyolefin polymeric
compositions. Exemplary polyolefin polymers with which the
flame retardants of this invention may be combined include
homopolymers of ethylene, propylene, butene, and hexene and
copolymers of two or more monomers, e.g., ethylene/propylene
copolymers, ethylene/butene copolymers, and ethylene/hexene
copolymers. A preferred class of polyolefin polymers which
can be used with the flame retardants of this invention are
propylene homo- and co-polymers thereof. A further des-
cription of polyolefin polymers capable of being used in this
invention can be found in Modern Plastics Encyclopedia, Vol,
52, No. 10A, McGraw-Hill, Inc., New York, ~ew York (1975),
and the Encyclopedia of Polymer Science and Technology,
Interscience Publishers, John Wiley & Sons, New York, N.Y.
(Vol, 2, Butylene Polymers- 1965, Vol. 6, Ethylene Polymers -
1967 and Vol, 11, Propylene Polymers - lg69).
The flame retardants of this invention can be
incorporated into or applied onto flammable polyolefin poly-
meric material by techniques which are standard or known to
g2 .
~ - 7 -
176
`:
those skilled in the art. See for example, J. M. Lyons,
"The Chemistry and Uses of Fire Retardants", Wiley-Inter-
science, New York, 1970, and Z. E, Jolles, 'Bromine and Its
Compounds", Academic Press, ~ew York, 1966. Depending on the
substrate and the amount of flame re'ardancy desired, from
about 1 to about 40 weight percent of the flame retardant
compound of formula (I) can be incorporated therewith. How-
ever, in most applications it is preferred to use from 1 to
about 25 weight percent of said compounds within the scope of
this invention. It should be noted that the optimum level
of additive of the flame retardant within the scope of this
invention depends upon the particular substrate being treated
as well as the level of flame retardancy desired. For example,
in polypropylene a flame retardant load level of from about 5
to about 25 percent by weight of the total polymeric com~
position is satisfactory.
In addition to the flame retardant compounds within
the scope of this invention, the flame retardancy of a polymer
can be further modified through the use of so-called
synergists" or enhancing agents, although preferably no
synergist or enhancing agent is used with the flame retardant
phosphates of this invention. These "enhancing agents" com-
prise the oxides and halides of groups IVA and VA of the
Periodic Table, and are further described in Modern Plastics
Encyclopedia, ibid., as well as U.S. Patents 2,993,924;
2,996,528, 3,205,196 and 3,878,165. Without limitation,
preferred enhancing agents include Sb203, SbC13, SbBr3, SbI3,
2 3' 2 5~ ZnB04, BaB204.H20, 2.ZnO.3B203,3.5H O
and stannous oxide hydrate. The more preferred enhancing
agent is antimony trioxide.
It is also within the scope of the present invention
to employ other materials in the present invention compositions
~9:17~i
where one so desired to achieve a particular end result.
Such materials include, without limitation, adhesion pro-
motors; antioxidants; antistatic agents; antimicrobials
colorants; heat stabilizers, light stabilizers and fillers.
The above mentioned materials, including filler, are more
fully described in Modern Plastics Encyclopedia, ibid,
The amount of the above described materials employed
in the present invention compositions can be any quantity
~ which will not substantially adversely affect the desired
results derived from the present invention compositions.
Thus, the amount used can be zero (0) percent, based on the
total weight of the composition, up to that percent at which
the composition can still be classified as a plastic. In
general, such amount will be from about ~/O to about 75% and
more specifically from about 1% to about 5~/O,
The following examples are provided for the purpose
of further illustration only and are not intended to be
limitations on the disclosed invention. Unless otherwise
specified, all temperatures are expressed in degrees centi-
grade, all weights are expressed in grams; and all volumes
are expressed in milliliters.
Example
Synthesis of 3,9-bis(2',4',6'-tribromophenoxy)-
2,4,8,10-tetraoxa-3,9-diphosphaspiro(5.5)undecane-3,9-dioxide
(compound 1 of Table I): !
The sodium salt of tribromophenol(282 grams) was
partially dissolved and suspended in one liter of acetonitrile.
To this mixture 119 grams of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-
diphosphaspiro(5.5)undecane-3,9-dioxide was added over a one-
half hour period. ~ slight exotherm was noted. Upon complete
addition, the mixture was stirred and heated to 70C. for three
hours. The resulting solid white mass was filtered and the
l~U~
product washed thoroughly with two liters of warm water. The
solid was subsequently washed twice with boiling acetone to
yield 322 grams (81 percent) of a white solid, m.p, 282~ to
286qC. Percent bromine calculated: 54.0, percent bromine
found: 52.06.
Example 2
Synthesis of 3,9-bis(2',3',4',5',6'-pentabromo-
phenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro(5.5)undecane-
3,9-dioxide (compound 6, Table I):
The sodium salt of pentabromophenol (460 grams) was
suspended in about 3 liters of acetonitrile in a 5-liter flask.
To the above suspension was slowly added 133.7 grams (0.45
mole) of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro-
(5.5)undecane-3,9-dioxide. The reactants were stirred for
half an hour and then heated gently. An additional liter of
acetonitrile was added to the reaction system and then said
system was heated up to 70C. and held at that temperature for
2.5 hours. The system was cooled, filtered, reslurried with
water, refiltered with a centrifuge, and then air dried. The
dried residue was given a boiling acetone wash, filtered
through a centrifuge, and then dried at 95C. A yield of
69.7 percent (377 grams) was obtained. Melting point: 324
to 326¢.
Comparative Example 3
Synthesis of 3,9-bis(2',3',4',5',6'-pentachloro-
phenoxy)-2,4j8,10-tetraoxa-3,9-diphosphaspiro(5.5)undecane-3,9-
dioxide.
Pentachlorophenol (97 grams, 0.364 mole), potassium
chloride (3.6 grams), and phosphorus oxychloride (447 grams)
were heated to the solutions refluxing temperature in a l-liter
~lask equipped with a magnetic stirrer. The reaction was re-
fluxed for 16 hours, cooled to room temperature, and then
- 10 -
lS~9176
filtered. Excess phosphorus oxychloride was removed under
vacuum. The pentachlorophenyl dichlorophosphate residue
(125 grams, 0.326 moles) was dissolved in toluene. Into
this solution was added 22.2 grams (0.163 mole) of penta-
erythritol. This reaction system was heated to reflux, held
at the reflux temperature 2.75 hours, cooled to room tempera-
ture, and then filtered. The residue was air dried and then
dried for 2 hours at 110C. Yield: 117 5 grams (95.3%),
Percent chlorine: theory: 46.9~/o' found: 46.44% melting
point: greater than 380C.
Comparative Example 4
3,9-bis-~2 14',6'-trichlorophenoxy)-2, 4 ~ 8,10-tetraoxa-3,9-di-
phosp~aspiro(5.5)undecane-3,9-dioxide.
The sodium salt of trichlorophenol (253 grams) was
partially dissolved and suspended in 1 liter of acetonitrile.
To this mixture 171 grams of 3,9-dichloro-2,4,8,10-tetraoxa-
3,9-diphosphaspiro(5.5)undecane-3,9-dioxide was added over a
one-half hour period. A slight exotherm was noted. Upon con~
plete addition, the mixture was stirred and heated to 70C.
for three hours. The resulting solid white mass was filtered
and the product washed thoroughly with warm water. The solid
was subsequently washed twice with cold acetone to yield 181
grams (51 percent) of a white solid, m.p. 283 to 28~C,
Percent chlorine calculated: 34.5 percent chlorine found:
30.9.
Comparative Example 5
3,9-bis(4'-chlorophenoxy~-2,4,8,10-tetraoxa-3,9-
diphosphaspiro(5.5)undecane-3,9-dioxide
Phosphorus oxychloride (3 kgm), potassium chloride
~40 grams), and p-chlorophenol (309 grams, 2.4 moles) were
magnetically stirred in a 3 liter flask and heated to reflux.
- 11 --
11~917~
The reactants were refluxed for 12.75 hours and then cooled to
room temperature. The reactants were filtered and excess phos-
phorus oxychloride was removed under vacuum. The crude product
(538 grams; 2.19 moles) was transferred to a 2 liter flask
into which was also added 502 ml of toluene and 152 grams
(1.09 moles) of pentaerythritol. These reactants were heated
to reflux and then held there for 5.25 hours. The reactants
were then cooled to room temperature, filtered, and the
residue dried under vacuum at 80C. The product was washed
with 3 liters of a 5~/O aqueous solution of acetone, filtered,
and then air dried. Yield: 348 grams (66.5%), Acid number:
0.86, Percent chlorine: theory: 14.~/o; found: 15.06%.
Exam~le 6
A solution of 600 grams of polystyrene, 2670 grams
of methylene chloride, and 60 grams of hexane, and 5 parts per
hundred resin (phr) of Example 1 was prepared. To the above
solution was added 3 grams of dicumyl peroxide as a flame
retardant synergist. This mixture was poured into an aluminum
dish and the methylene chloride was allowed to evaporate,
Following this, the casting was steamed to produce a crude
foam. This foam was then cut into sufficient specimens of
appropriate sizes in order to subject said foam to various
tests and the data obtained therefrom are reported in Table
II.
The same processing conditions as above were used to
maXe additional polystyrene foam samples having different flame
retardant load levels. These samples were tested in the same
manner and the results obtained are also tabulated in Table
II,
17~
The flame retardant of Example I (4~O of the total
mixture by weight) was dry mixed with high impact polystyrene
(HIPS) resin (52% by weight), and ~O by weight antimony oxide
(Cosden 825* TV-K brand HIPS Cosden Oil & Chemical Co., Big
Springs, Texas). The mixture was melt blended in a compounding
machine under the following conditions: temperature: 240C.,
rpm: 100 to 120, and mixing time: 2 to 3 minutes (Prep-Center*
brand compounding machine, C.W. Braebender Instruments, Inc.,
S. Hackensack, New Jersey). The discharge mass was cooled,
ground, let down to a flame retardant load level of l~/o by
weight and 3.6% by weight antimony oxide by dry blending the
ground concentrate discharge mass with the HIPS resin, and then
injection molded using a 30-ton Newbury 1 ounce injection
molding machine under the following parameters: screw speed:
250 rpm, injection pressure: initial: 2000 pounds per square
inch (psi), internal barrel temperature: rear zone: 440F.,
front zone: 470F.; cycle time: 60 seconds (sec.); total
injection time: 20 sec., total stroke time: 5 sec. The final
HIPS polymeric composition was subjected to various tests' and
the data obtained therefrom are reported in Table II.
The same processing conditions as above were used to
make additional HIPS Polymeric samples having different flame
retardant and antimony oxide load levels. Using the same
injection molding conditions as above save that the internal
barrel temperature rear and front zones were 420 and 470F.
respectively, HIPS samples were also prepared with neither
flame retardant additive nor antimony oxide present. The
absence of the prior melt blending step and the difference in
the rear and front zone internal barrel temperatures have no
impact on the flame retarding efficacy of the HIPS base resin.
* trademark
B
- 13 -
11'~176
These samples were tested in the same manner and the results
obtained are also tabulated in Table II.
Example 8
The flame retardant o~ Example l (36% of the total
mixture by weight) was dry mixed with low density polyethylene
(LDPE) resin (64% by weight) (Union Carbide 3900 brand LDPE,
Union Carbide Corp., New York, New York). The mixture was
melt blended in a Brabender Prep-Center compounding machine
under the following conditions: temperature: 220C., rpm: lO0~
and mixing time: 2 to 3 minutes. The discharge mass was cooled,
ground, let down to a flame retardant load level of l~/o bv
weight flame retardant by dry blending the ground concentrate
discharge mass with the LDPE resin, and then injection molded
using a 30-ton Newbury l ounce injection molding machine under
the following parameters: screw speed: 250 rpm; injection
pressure: initial: 2000 psi; internal barrel temperature:
rear zone: 410F., front zone: 440 F.; cycle time. 60 sec,,
total injection time: 20 sec., total stroke time: 3 sec. The
final LDPE polymeric composition was subjected to various tests
and the data obtained therefrom are reported in Tables II and
III.
Using the same injection molding conditions as
above, additional LDPE samples were prepared without any
flame retardant additive present. The absence o~ the prior
melt blending step has no impact on the flame retarding
efficacy of the LDPE base resin. These samples were tested
in the same manner and the results obtained are also reported
in Tables II and III.
- 14 -
Example 9
The flame retardant of Example 1 (3~/O of the total
mixture by weight) was dry mixed with polypropylene resin
(7~/O by wei~ht) (Hercules 6823 brand polypropylene, Hercules,
Inc., Wilmington, Delaware). The mixture was melt blended in
a Brabender Prep~Center compounding machine under the following
conditions: temperature: 220C.; rpm: 100, and mixing time:
1 to 2 minutes. The discharge mass was cooled, ground, let
down to a flame retardant load level of 12.5% by weight flame
retardant by dry blending the ground concentrate discharge
mass with the polypropylene resin and then injection molded
using a 30-ton Newbury 1 ounce injection molding machine under
the following parameters: screw speed: 250 rpm' injection
pressure: initial: 2000 psi, internal barrel temperature:
rear zone: 410F., front zone: 440 F,; cycle time: 45 sec.,
total injection time: 20 sec.; total stroke time: 4.5 sec.
The final polypropylene polymeric composition was subjected
to various tests and the data obtained therefrom are reported
in Tables II and III.
The same processing conditions as above, save that
in the case of compound of Example 2 the compounding parameters
were: temperature: 225C., rpm: 120, and mixing time: 2 to 3
minutes and cycle time was 60 seconds and the stroke time was
4.5 seconds, and in the case of compound of Example 3 the mixing
time was 2 to 3 minutes, the cycle time was 60 seconds and the
total stroke time was 4 seconds. The different parameters
used in preparing these additional polypropylene polymeric
samples have no impact on the flame retardant efficacy of the
flame retardant additive. Also, using the same-injection
molding conditions as above, additional polypropylene poly-
meric samples were prepared without any flame retardant
additive present, The absence of the prior melt blending step
- 15
76
has no impact on the flame retardant efficacy of the flame
retardant additive. These samples were tested in the same
manner and the results obtained are also reported in Tables
II and III.
Table II clearly demonstrates that the flame retardant
compounds within the scope of this invention, as exemplified
by Example 1, are not universal flame retardants capable of
imparting effective flame retardancy to all polymeric mate-
rials treated therewith. However, Table II clearly depicts
this invention's discovery of the unobvious flame retardant
efficacy of the flame retardant compounds within the scope
o~ this invention, as exemplified by compounds of Examples 1
and 2 in polyolefins, as exemplified by low density poly-
ethylene and polypropylene~ As vividly displayed in Table II,
of the various polymeric compositions containing an exemplary
flame retardant compound within the scope of this invention,
only flame retarded polyolefins exhibit an exceptionally high
increment in Oxygen Index. These beneficial results are
achieved without the use of an "enhancing" agent.
Other flame retardant compounds within the scope of
this invention which also impart an exceptionally high incre-
ment in Oxygen Index to flame retarded polyolefins include
3,9-bis(2',4' r 5',6'-tetrabromophenoxy)-2,4,8,10-tetraoxa-3,9-
diphosphaspiro(5.5)undecane-3,9-dioxide, and 3,9-bis(2',4',6'-
tribromophenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro(5.5)-
undecane-3,9-disulfide.
.
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Example 10
The compound of Example 4 (36% of the total mixture
by weight) was dry mixed with LDPE resin (64% by weight)
(Union Carbide 3900 brand LDPE, Union Carbide Corp., ~ew York,
New York). The mixture was melt blended in a Brabender Prep-
Center compounding machine under the following conditions:
temperature: 220~C., rpm: 100; and mixing time: 2 to 3 minutes.
The discharge mass was cooled, ground, let down to a flame
retardant load level of l8/O by weight flame retardant by dry
blending the ground concentrate discharge mass with the LDPE
resin, and then injection molded using a 30-ton Newbury 1
ounce injection molding machine under the following para-
meters: screw speed: 250 rpm; injection pressure: initial:
2000 psi; internal barrel temperature: rear zone: 410F.,
front zone: 440F.; cycle time: 60 sec., total injection
time: 20 sec., total stroke time: 3.5 sec. The final LDPE
polymeric composition was subjected to various tests and the
data obtained therefrom are reported in Table III.
The difference in parameters used to prepare the
various LDPE samples of Examples 8 and,10 has no impact on
the flame retarding efficacy of the flame retardant additive.
Example 11
The compound of Example 4 (25% of the total mixture
by weight) was dry mixed with polypropylene resin (75% by
weight) (Hercules 6823 brand polypropylene, Hercules, Inc ,
Wilmington, Delaware). The mixture was melt blended in a
Brabender Prep-Center compounding machine under the following
conditions: temperature: 220C., rmpo 100, and mixing time:
2 to 3 minutes. The discharge mass was cooled, ground, let
down to a flame retardant load level of 12.5% by weight flame
retardant by dry blending the ground concentrate discharge
mass with the polypropylene resin, and then injection molded
- 18 -
~,A
9~7~
using a 30-ton Newbury 1 ounce injection molding machine under
the following parameters: screw speed: 250 rpm' injection pres-
sure: initial: 2000 psi, internal barrel temperature: rear
zone: 410 F., front zone: 440F., cycle time: 60 sec.,
total injection time: 20 sec.' total stroke time: 4.5 sec.
The final polypropylene po.lymeric composition was subjected
to various tests and the data obtained therefrom are reported
in Table III.
The same processing conditions as above, save that
the compounding temperature was 210C,, the rpm was 120, and
the total stroke time was 4 seconds, were used to prepare
additional polypropylene samples containing compound B. The
difference in parameters used to prepare the various polypro-
pylene samples of Examples 9 and 11 has no impact on the flame
retarding efficacy of the polypropylene base resin.
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Based on this disclosure, many other modifications
and ramifications will naturally suggest themselves to those
skilled in the art. These are intended to be comprehended
as within the scope of this invention.
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