Note: Descriptions are shown in the official language in which they were submitted.
8CH-19~4
13DSO~133
This invention is directed to a flame-retardant
composition comprising in admixture a thermoplastic polymer,
a flame-retardant additive and a minor amount of an organo-
polysiloxane polymer
Background of the Invention
With tlle increasing concern for safety, there is
a positive move towards providing safe materials for public
and household use. One particular area of need is that of
providing flame resistant or flame retardant products for
use by the ultimate consumer. As a result of this demand,
many products are being required to meet'certain flame
retardant criteria both by local and féderal government
and the manufacturers of such products. One particular set
of conditions employed as a measuring standard for flame
retardancy is set forth'in Underwriters Laboratories, Inc.
Bulleti~ 94. This Bulletin sets forth certain conditions by
whi:ch'materials are rated for seIf-extinguishing characteristics.
It is known to use'organopolysiloxane in admixture
with'polycarbonates -to provide'a composition having good mold
release properties from U.S. patent 2,9g9,835. Also, U.S.
patent 3,'087,908 discloses resinous material comprising
organosiloxane in admixture with polycarbonates, which
composition facilitates the formation of clear films which
are'free from blemishes, undesirabIe color effects, b~bbles,
and craters.
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8CH-198~
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However, none of the above references disclose
that when a minor amount of a particular organopolysiloxane
polymer is mixed with a thermoplastic polymer and a flame
retardant additive, -the thermoplastic polymer is rendered
flame retardant.
The organopolysiloxane polymer additive is able
to stop the dripping of molten, flame particles from burning
thermoplastic parts. In the case of self-extinguishing
polymers, these materials can be ignited and do burn as long
as the ignition source is present but extinguish themselves
within a few seconds after its removal. ~Iowever, during
the burning period, before flame-out, the self-
extinguishing polymer tends to drip molten flaming
fragments which will ignite other material situated
below the first fire. However, the instant additive in
admixture with the aromatic polycarbonate prevents this
dripping of molten, flaming particles.
Description of the Invention
This invention relates to a flame-retardant
composition comprising in admixture (A) an alkenylaromatic
pol~mer; (B) a 1ame-retardant additive and (C) a minor
amount of diorganopolysiloxane polymer wherein the organo
substituents therein are selected from the group
consisting of alkyl, aryl and vinyl radicals and mixtures
thereof. The amount of organopolysiloxane polymer
can vary but preferably is present in from 0.5 to about
8CH-1984
~S~ 3
5.0 weight percent based on the weight of the alkenyl-
aromatic polymer.
The diorganopolysiloxane polymers employed in
the practice of this invention are gums which have a
viscosity of from abbut 80,000,000 to 100,000,000 centistokes.
These high molecular weight diorganopolysiloxane polymers
are prepared by methods known in the art, as for example,
by the methods set forth in U.S. patents 2,445,794; 2,~48,756;
2,484,595 and 3,514,424. The diorganopolysiloxane polymers
of the present invention consist essentially of silicon
atoms, oxygen atoms and organic groups selected from the
group consisting of al~l such as lower alkyl, aryl such as
phenyl, and substituted phenyl such as tetrachloro phenyl
radicals,etc. and vinyl radicals and mixtures thereof.
Preferably~ the organic groups are selected from the group
consisting of methyl, phenyl and vinyl radicals. From 0 to
35 mole percent of the organic groups being silicon-bonded
aryl radicals, preferably phenyl radicals and from 0 to 2
mole percent of the organic groups being silicon-bonded vinyl
radicals.
The "alkenylaromatic polymers" of the present
invention include polymers consisting of styrene. The
styrene polymer may be either a styrene homopolymer of
a styrene copolymer of at least 50 weight percent of
styrene with the balance being any other monomer
copolymerizeable with styrene monomer. This also includes
the high impact polystyrenes which are prepared by
8CH- 1 9 8 4
~S~33
polymerizing skyrene in the presence of polybutadiene
to graft copolymerize the polybutadiene onto the styrene
polymer chain that is formed during polymerization of the
styrene monomer. Also included are the styrene-bu-tadiene
block and random copolymers wherein the butadiene may be
present in an amount of from 10-50 weight percent of the
styrene polymer.
Also, alkenylaromatic polymers include a
terpolymer of a vinyl aromatic-acrylonitrile-butadiene.
Additionally, alkenylaromatic compounds such as
methylstyrene, the mono-, di-, tri-, tetra- and penta-
chlorostyrenes and ~ -methylstyrenes, and the nuclearly
alkylated styrenes and ~-alkylstyrenes such as ortho-
and para-methylstyrenes, ortho- and para-ethylstyrene,
ortho- and para-methyl- ~ -methylstyrene and the like may
be copolymerized with acrylonitrile, butadiene, and the
like. Alternatively, the alkenylaromatic polymers can
include a blend of a vinyl aromatic-acrylonitrile copolymer
and a vinyl aromatic-butadiene copolymer. These can range
~0 from 10-90 weight percent of either constituent of the
copolymer blend. Preferably, however, a 50-50 weight
percent is desirable.
The flame-retardant additives which may be added
to the thermoplastic resin comprise a family of chemical
compounds well known to those skilled in the art.
Generally speaking, the more important of these compounds
contain chemical elements employed for their
ability to impart flame resistance, e.g., bromine,
8CH-1984
1~50~3
chlorine, antimony, phosphorus and nitrogen. It is
preferred that the flame-retardant additive comprise a
halogenated organic compound (brominated or chlorinated);
a halogen-containing organic compound in admixture with an
organic or inorganic antimony compound, e.g., antimony
oxide; elemental phosphorus or a phosphorus compound; a
halogen-containing compound in admixture with a phosphorus
compound or compounds containing phosphorus-nitrogen bonds
or a mixture of two ore more of the foregoing.
The amount of flame-retardant additive that may
be used will be from about 10 to about 30 parts by weight
per hundred parts of resin. Synergists, e.g., inorganic
or organic antimony compounds, such as antimony oxidel will
be used at about 1 to 10 parts by weight per 100 parts of
resln
Among the useful halogen-containing compounds are
those of the formula
\ ( a ~ ~b \ ~
wherein n is 1 to 10 and R is an alkylene, alkylidene
or cyclo-aliphatic linkage, e.g., methylene, ethylene,
propylene, isopropylene, isopropylidene, butylene,
isobutylene, amylene, cyclohexylene, cyclo-
pentylidene, and the like; a linkage selected from
the group consisting of ether; carbonyl; a sulfur-containing
~CH-198~
~5~1~33
linkage, e.g., sulfide, sulfoxide, sulfone, thio-
carbona-te; a phosphorus-containing linkage, and the like.
R can also consist of two or more alkylene or alkylidene
linkages connected by such groups as aromatic, ether,
ester, carbonyl, sulfide, sulfoxide, sulfone, a phosphorus-
containing linkage, and the like. R can be derived from a
dihydric phenol, e.g., bisphenol-A, and the like.
Other groups which are represented by R will occur to those
skilled in the art.
Ar and Ar' are mono- or polycarbocyclic aromatic
groups such as phenylene, biphenylene, terphenylene,
naphthylene, and the like. Ar and Ar' may be the same or
different.
Y is a substituent selected from the group
consisting of organic, inorganic or organometallic radiccLls.
The substituents represented by ~ include (1) halogen,
e.g., chlorine, bromine, iodine, or fluorine or (2)
hydroxy or ether groups of the general formula OE,
wherein E is hydrogen or a monovalent hydrocarbon radical
similar -to X or (3) monovalent hydrocarbon groups of
the type represented by R or (~) other substituents, e.g.,
cyano, etc., said substituents being essentially inert
provided there be at least one and preferably two halogen
atoms per aryl, e.g., phenyl, nucleus.
X is a monovalent hydrocarbon groups exemplified by the
following: alkyl, such as methyl, ethyl, propyl, isopropyl, butyl,
8CH--1984
1(~5(~3
decyl, and the like; aryl groups, such as phenyl, naphthyl,
biphenyl, xylyl, tolyl, and the like; aralkyl groups, such
as benzyl, ethylphenyl, and the like; cycloaliphatic groups,
such as cyclopentyl, cyclohexyl, and the like; as well as
monovalent hydrocarbon groups containing inert substituents
therein. It will be understood that where more than one X
is used they may be alike or different.
The letter d represents a whole number xanging from
l to a maximum equivalent to the number of replaceable
hydrogens substituted on the aromatic rings comprising
Ar or Ar'. The letter e represents a whole number ranging
from 0 to a maximum controlled by the number of replaceable
hydrogens on R. The letters a, b, and c represent whvle
n~mbers including 0. When b is not 0, neither a nor c may
be 0. Otherwise either a or c, but not both, may be 0.
Where b is 0, the aromatic groups are joined by a direct
- carbon-to-carbon bond.
The ~ substi-tuents on the aromatic groups, Ar
and Ar' can be varied in the ortho, meta or para positions
on the aromatic rings and the groups can be in any possible
geometric relationship with respect to one another.
Included within the scope of the bisphenols
included in the above formula are the following:
~CH-1984
11 C~5~83
2,2-bis (4-hydroxy, 3,5-dichlorophenyl)propane
bis (4-hydroxy, 3-chlorophenyl)methane
bis (4-hydroxy, 3,4-dibromophenyl)methane
1,2-bis (4-hydroxy, 3,5-dichlorophenyl)ethane
l,l-bis (4-hydroxy, 3,5 dichlorophenyl)ethane
3,3-bis (4-hydroxy, 3,5-dichlorophenyl)pentane
bis (4-hydroxy, 3,5-dichlorophenyl)cyclohexylmethane
The preparation of these and other applicable
bisphenols are known in the art. In place of the divalent
aliphatic group in the above examples may be substituted
sulfide, sulfoxy and the like.
Included within the above structural formula
are substituted benzenes exemplified by tetrabromobenzene,
hexachIorobenzene, hexabromobenzene, and biphenyls such
as 2,2'-dichlorobiphenyl, 2,4'-dibromobiphenyl, 2,4'-
dichlorobiphenyl, hexabromobiphenyl, octabromobiphenyl,
decabromobiphenyl and halogenated diphenyl ethers, containing
2 to 10 halogen atoms.
A preferred flame-retardant additive which
may be included within this invention is a copolycarbonate
which is derived from a halogen-substituted dihydric
phenol and a dihydric phenol, said halogen preferably
being chlorine or bromine. Preferably, this copoly-
carbonate is the product of a halogenated bisphenol-A such
as tetrabromobisphenol-A and tetrachlorobisphenol-A and a
8C~I-19 8a~
:~L05~)183
dihydric phenol such as bisphenol-A. Preferably, this
copolycarbonate consists of 75 to 25 weight percent of
the product of tetrabromobisphenol-A and, correspondingly,
25 to 75 weight percent of the product of bisphenol-A
based on the weight of the copolycarbonate. The preparation
of this copolycarbonate is set forth in U.S. patent 3,334,154.
Another preferred flame-retardant additive
which may be included within this invention is low molecular
weight polymers of a carbonate of a halogenated dihydric
phenol. Such polymers may contain from 2 to 10 repeating
units of the formula
o l , )
wherein Rl and R2 are hydrogen, (lower)alkyl or phenyl,
xl and x2 are bromo or chloro and m and r are from 1 to 4.
The polymeric additives will have a low volatility when
heated above 200C., and a softening point of less than
about 300C. They will be used alone or in combination
with synergists, such as inorganic or organic antimony-
containing compounds.
8CH-1984
~61 SO~ ~33
These polymeric additives can be made by
polymerizing a mixture of a halogenated dihydric phenol
and a ehain stopper, e.g., an alcohol, carboxylic acid,
earboxylic aeid halide or, preferably a monohydric
phenol, and most preferably a halogenated phenol and
phosgene or a reaeti~e derivative thereof in the presenee
of an aeid acceptor, e.g., an amine or causticO Details
concerning the preparation and use of such compounds are
given in the Canadian patent application of Daniel W. Eox,
"Flame Retardant Compounds and Thermoplastic
Compositions Containing the Same", Serial No. 167,809,
filed on April 3r 1973.
Another preferred additive can be made by
polymerizing a mixture of tetrabromobisphenol-A and
2,4,6-tribromophenol with phosgene in either methylene
chloride in the presence of pyridine or in methylene
chloride containing triethylamine in admixture with
an aqueous caustie phase. The product of such a process
will be a polymer of the formula:
-- 10 --
8CH - 19 8 4
~a~5~ 3
m
m
o
m ~m
~$ ''
o
o~
m r~r~
8CH-1984
S~ 33
wherein the average number of repeating units, n, will
be from about 3 to about 7, and the softening point will
be in the range of from 200 to 260C.
Inorganic and organic antimony compounds are
widely available or can be made in known ways. In
preferred embodiments, the type of antimony compound
used is not critical, being a choice primarily based
on economics. For example, as inorganic antimony compounds
there can be used antimony oxide, (Sb203); antimony
phosphate; KSb(OH)6; NH4SbF6; SbS3; and the like.
A wide variety of organic antimony compounds can also be
used, such as antimony esters with organic acids; cyclic
alkyl antimonites; aryl antimonic acids, and the like~
Illustrative of the organic antimony compounds, including
inorganic salts of such compounds are: RSb tartrate,
Sb caproate; Sb(OCH2CH3)3; Sb(OCH(CH3)CH2CH3)3,
Sb polymethylene glycolate; triphenyl antimony; and
the like. Especially preferred is antimony oxide.
It is also regarded to be among the features
of this invention to include in the compositions, other
ingredients, such as fillers, mold release agents, pigments,
stabilizers, nucleating agents, and the like, in conventional
amounts for their conventionally employed purposes.
The manner of adding the flame retardant additives, and
the diorganopolysiloxane polymer to the thermoplastic resin is not
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8CH-1984
J~)5~ 3
critical; is conventional; and will be obvious to those
skilled in the art. This composition is passed through
an extruder at a temperature dependent on the needs
of the particular compositions. The resulting extrudate
is comminuted into pellets or other suitable shapes.
This mixture is then fed into a conventional molding machine
which produces a molded product.
Description o~ the Preferred Embodiment
The following Examples are set forth to illustrate
more clearly the principle and practice o~ this invention
to those skilled in the art. Unless otherwise specified,
where parts or percents are mentioned, they are parts
or percents by weight.
Example I
75 parts by weight of an acrylonitrile-
butadiene-styrene terpolymer (40, 20 and 40 weight percent,
respectively) are blended with 20 parts by weight of
resin of poly(2,2-bis (3,5-dibromo-4-hydroxyphenyl)propane
carbonate) terminated with tribromophenoxy groups
(having about 5 repeating units and prepared by reacting
0.06 moles of tetrabromobisphenol-A, 0.02 moles of
tribromophenol and phosgene in methylene chloride and
pyridine), and 5 parts by weight of antimony
oxide. The mixture is then fed into an extruder, and
the extrudate is comminuted into pellets. The
pellets are then injection molded into test bars which are
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8CH-198~
:105~ 3
.090" x .500". These bars are then subjected to
the Underwriters Laboratories Subject 94 flame test.
The results are given in the TABLE.
Example II
7S part~ by weight of an acrylonitrile-
butadiene-styrene terpolymer (40, 20 and 40 weight percent,
respectively) are blended with 20 parts by weight of
resin of poly(2/2-bis(3,5-dibromo-4-hydroxyphenyl~propane
carbonate~ terminated with tribromophenoxy groups
(having about 5 repeating units and prepared by
reacting 0.06 moles of tetrabromobisphenol-~, 0.02 moles
of tribromophenol and phosgene in methylene chloride
and pyridine), and 5 parts by weight of antimony oxide.
To this is added by dry blending 1.5 parts by weight of
high molecular weight methyl phenyl vinyl siloxane. The
mixture is extruded into test bars as in Example I and
subjected to ~he UL-94 flame test. The results are
given in the TABI,E.
Example II
Example II is repeated except that 2.5
parts by weight of high molecular weight methyl phenyl
vinyl siloxane is added instead of 1.5 parts by weight.
The mixture is extruded into test bars as in Example I and
subjected to the UL-9~ flame test. The results are given
in the TABLE.
8CH-1984
11[~56~3
Example IV
70 parts by weight of an acrylonitrile-
butadiene-styrene terpolymer (40, 20 and 20 weight
percent, respectively) are blended with 25 parts by
weight of resin of poly(2,2-bis(3,5-dibromo-4-
hydroxyphenyl)propane carbonate) terminated with tri-
bromophenoxy groups (having about 5 repeating units and
prepared by reacting 0.0~ moles of tetrabromobisphenol-A,
0.02 moles of tribromophenol and phosgene in methylene
chloride and pyridine), and 5 parts by weight of
antimony oxide. To this is added by dry blending 1.5
parts by weight of high molecular weight methyl phenyl
vinyl siloxane. The mixture is extruded into test bars
as in Example I and su~jected to the UL-9~ flame test.
The results are given in the TABLE.
Example V
Example I is repeated except that high impact
polystyrene is used instead of the acrylonitrile-
butadiene-styrene terpolymer. The mixture is extruded
into test bars as in Example I and subjected to
the UL-94 flame test. The results are given in the
TABLE'.
Example VI
Example III is repeated except that high impact poly-
styrene is used instead of the acrylonitrile butadiene-styrene
8CEI-1984
~5~)183
terpolymer~ The mixture is extruded into test bars
as in Example I and subjected to the UL-94 flame
test. The results are given in the TABLE.
Example VII
Example IV is repeated except that high
impact polystyrene is used instead of the acrylonitrile-
butadiene-styrene terpolymer. The mixture is extruded
into test bars as in Example I and subjected to the
UL-94 flame test. The results are given in the
TABLE.
Example VIII
Example IV is repeated except that the
additive is a diphenyl dimethyl siloxane fluid (viscosity
l90 centistokes) instead of the methyl phenyl vinyl
siloxane. The mixtures is extruded into test bars as
in Example I and subjected to the UL-94 flame test.
The results are given in the TABLE.
Example IX
Example VI is repeated except that the
additive is a diphenyl dimethyl siloxane fluid (viscosity
l90 centistokes) instead of the methyl phenyl vinyl
siloxane. The mixture is extruded into test bars as in
Example I and subjected to the UL-94 flame test. The
resul~s are given in the TABLE.
8CH-1984
~5~)~83
Example ~
Example IV is repeated except that the
additive is a dimethyl silicone fluid containing 3 mole
percent tetrachlorophenyl siloxy units, the remainder
being mèthyl substituents and containing trimethyl siloxy
chain stopping units (viscosity 70 centistokes) instead
of the methyl phenyl vinyl siloxane additive. The
mixture is extruded into test bars as in Example I and
subjected to the UL-94 flame test. The results are
given in the TABLE.
Example XI
Example VI is repeated except that the aclditive
is a dimethyl silicone fluid containing 3 mole percent
tetrachIorophenyl siloxy units, the remainder being
methyl substituents and containing trimethyl siloxy
chain stopping units (viscosity 70 centistokes) instead
of the methyl phenyl vinyl siloxane additive. The
mixture is extruded into test bars as in Example I
and subjected to the UL-94 flame test. The results
are given in th.e TABLE.
The test bars of the Examples are evaluated
in accordance with the test procedure of Underwriters
Laboratories, Inc. Standard UL-94, September, 1972,
Vertical Burning Test for Classifying Materials. In
accordance wi~h the test procedure, materials
are classified as either SE-O, SE-I or SE-II. The
8CEI-198~
;IL~50~3
results are based on 5 specimens, each supported
vertically. The criteria for SE rating per UL-94 is
briefly as follows:
"SE-0": Average flaming and/or glowing after removal
of the igniting flame shall not exceed 5
seconds and none of the specimens burn
for longer than 10 seconds for shall drip
flaming particles which ign.ite absorbent
cotton that is placed 12 inches below
the specimen.
"SE-I": Average flaming and/or glowing after
removal of the igniting flame shall
not exceed 25 seconds and no one sample
shall exceed 30 seconds nor shall the
specimen drip flaming particles that
ignite absorbent cotton that is placed
~ 12 inches below the specimen.
"SE-II": Average flamlng and/or glowing after
removal of the igniting flame shall not
exceed 25 seconds and no one sample
shall exceed 30 seconds but the specimens
may drip flaming particles which ignite
absorbent cotton.
Further~ UL-9~ states that if only one specimen from a set
of five specimens fails to comply with the
requirements, another set of five specimens shall
be tested. All specimens from this second
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8CH-1984
1050~83
set shall comply with the appropriate requirements in
order ~or the material in that thickness to be classified
"SE-0", "SE-I" or "SE-II".
TABLE
U.L. 94
Sam~le Classification
_
Example I SE-II
Example II SE-I
Example III SE-I
Example IV SE-0
Example V SE~II
Example VI SE-I
Example VII SE-I
Example VIII SE-II
Example IX SE-II
Example X SE-II
Example XI SE-II
As seen by the Examples, the composition of the
instant invention is classified as either SE-I or
SE-0 while the compositions with no additive (Examples
I and V) and the compositions with a low molecular weight
polysiloxane (Examples VIII to XI) are classified as
SE-II when tested by the procedure of the UL-94 test.
It will thus be seen that the objects set forth above
among those made apparent from the preceding description are
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8CH-1984
~S1~33
efficiently attained, and since certain changes may be
made in carrying out the above process and in the
composition set forth without departing from the scope
of this invention, it is intended that all matters contained
in the above description shall be interpreted as
illustrative and not in a limiting senseO
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