U.S. patent application number 16/246617 was filed with the patent office on 2019-05-16 for process for preparing bromine- containing polymers.
The applicant listed for this patent is Bromine Compounds Ltd.. Invention is credited to Ron Frim, Mark Gelmont, Lior Melamed, Renata Yelizarov, David Yoffe, Michael Yuzefovich.
Application Number | 20190144754 16/246617 |
Document ID | / |
Family ID | 53969404 |
Filed Date | 2019-05-16 |
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United States Patent
Application |
20190144754 |
Kind Code |
A1 |
Gelmont; Mark ; et
al. |
May 16, 2019 |
PROCESS FOR PREPARING BROMINE- CONTAINING POLYMERS
Abstract
The invention provides a process for preparing
bromine-containing polymers, comprising a Friedel-Crafts alkylation
reaction of pentabromobenzyl halide with a polymer reactant which
contains one or more six-membered aromatic ring(s) in its repeat
unit, in the presence of at least one Friedel-Crafts catalyst. The
so-formed bromine-containing polymers, having pendent
--CH.sub.2C.sub.6Br.sub.5 groups attached to at least a portion of
the six-membered aromatic rings of the polymer, with a carbon ring
atom of said six-membered aromatic ring being bonded to the
aliphatic carbon of said --CH.sub.2C.sub.6Br.sub.5 pendent group,
are also provided. These bromine-containing polymers are useful as
flame retarding agents.
Inventors: |
Gelmont; Mark; (Haifa,
IL) ; Yuzefovich; Michael; (Haifa, IL) ;
Yoffe; David; (Haifa, IL) ; Yelizarov; Renata;
(Kiryat Yam, IL) ; Frim; Ron; (Haifa, IL) ;
Melamed; Lior; (Beer Sheva, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bromine Compounds Ltd. |
Beer Sheva |
|
IL |
|
|
Family ID: |
53969404 |
Appl. No.: |
16/246617 |
Filed: |
January 14, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15323869 |
Jan 4, 2017 |
10227531 |
|
|
PCT/IL2015/050700 |
Jul 7, 2015 |
|
|
|
16246617 |
|
|
|
|
62021722 |
Jul 8, 2014 |
|
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Current U.S.
Class: |
524/409 ;
528/394 |
Current CPC
Class: |
C08K 5/005 20130101;
C08K 3/2279 20130101; C09K 21/14 20130101; C08G 65/485 20130101;
C08L 23/14 20130101; C08L 27/10 20130101; C09K 21/02 20130101; C08L
77/06 20130101; C08K 7/14 20130101; C08L 27/24 20130101; C08F 8/24
20130101; C08F 8/22 20130101; C08L 2201/02 20130101; C08K 5/098
20130101; C08F 8/22 20130101; C08F 8/24 20130101; C08F 112/08
20130101; C08F 8/24 20130101; C08F 112/08 20130101; C08L 77/06
20130101; C08K 3/2279 20130101; C08K 5/005 20130101; C08K 5/098
20130101; C08K 7/14 20130101; C08L 27/24 20130101; C08L 23/14
20130101; C08L 27/10 20130101; C08K 3/2279 20130101 |
International
Class: |
C09K 21/14 20060101
C09K021/14; C08L 27/24 20060101 C08L027/24; C08L 27/10 20060101
C08L027/10; C08K 7/14 20060101 C08K007/14; C08K 5/098 20060101
C08K005/098; C08K 5/00 20060101 C08K005/00; C08K 3/22 20060101
C08K003/22; C08F 8/22 20060101 C08F008/22; C09K 21/02 20060101
C09K021/02; C08L 23/14 20060101 C08L023/14; C08L 77/06 20060101
C08L077/06; C08G 65/48 20060101 C08G065/48; C08F 8/24 20060101
C08F008/24 |
Claims
1. A process for preparing bromine-containing polymers, comprising
a Friedel-Crafts alkylation reaction of pentabromobenzyl halide
with a polymer reactant having one or more six-membered aromatic
ring(s) in its repeat unit, wherein said reaction takes place in a
solvent in the presence of at least one Friedel-Crafts
catalyst.
2. A process according to claim 1, wherein the pentabromobenzyl
halide is pentabromobenzyl bromide.
3. A process according to claim 1, wherein the polymer starting
material is represented by Formula III or Formula IV: ##STR00007##
wherein in Formula III, R is a linear or branched aliphatic chain
or bromine; k is independently an integer from 0 to 4; A is
selected from the group consisting of null, --CH.sub.2CH.sub.2--,
--CH.sub.2CH.dbd.CHCH.sub.2--, --CH(CH.sub.3)CH.sub.2-- and
--CH.sub.2--CH.dbd.C(CH.sub.3)CH.sub.2--; n and m are the number of
units in the polymer chain; and wherein in Formula IV, X is
selected from the group consisting of null, O, S, --CH.sub.2--,
--CH.sub.2CH.sub.2--, and n is the number of units in the polymer
chain.
4. A process according to claim 3, wherein the polymer starting
material is either a polymer of Formula III, with k=0, A=null and
m=0 (polystyrene) or a polymer of Formula IV, with X.dbd.O
(poly(phenylether)).
5. A process according to claim 4, comprising charging a reaction
vessel with a solvent, a polymer starting material which is
polystyrene, pentabromobenzyl halide and one or more catalysts used
for Friedel-Crafts alkylation, allowing the Friedel-Crafts
alkylation to reach completion and recovering bromine-containing
polystyrene having pendent --CH.sub.2C.sub.6Br.sub.5 groups.
6. A process according to claim 1, wherein a mixture of AlCl.sub.3
and SnCl.sub.4 is used to catalyze the reaction.
7. A process according to claim 1, further comprising a step of
subjecting the so-formed pentabromobenzyl-substituted polymer to
bromination reaction.
Description
[0001] This application is a divisional of U.S. application Ser.
No. 15/323,869, which is the U.S. national stage of International
Application No. PCT/IL2015/050700 filed Jul. 7, 2015, which claims
the priority benefit of U.S. 62/021,722 filed Jul. 8, 2014, the
entire respective disclosures of which are incorporated herein by
reference.
[0002] The present invention provides a novel class of high
molecular weight polymers having pendent pentabromobenzyl groups,
which are suitable for use as flame retardants in flammable
materials (e.g., polyamide, polypropylene and
acrylonitrile-butadiene-styrene compositions).
[0003] Brominated compounds are known to be highly effective as
flame retardants, and in many cases they constitute the only viable
option for reducing the fire risk of synthetic materials. There
exists a need to develop new, polymeric high molecular weight,
brominated flame retardants. It is postulated that the higher the
molecular weight of the brominated flame retardant, the lower is
its volatility and its ability to bio-accumulate in living
tissues.
[0004] Low molecular weight compounds containing a pentabromobenzyl
moiety are known in the art. Pentabromobenzyl acrylate (EP 481126),
pentabromobenzyl terephthalate (DE 33 20 333) and pentabromobenzyl
tetrabromophthalate (EP 47866) have been reported to be useful in
flame retarded polymer compositions. Furthermore, poly
(pentabromobenzyl acrylate) is used as a flame retardant agent in
flammable materials. Hereinafter, the pentabromobenzyl group is
sometimes described by its molecular structure:
##STR00001##
[0005] or its molecular formula --CH.sub.2C.sub.6Br.sub.5.
[0006] In a co-assigned international patent application
PCT/IL2014/000002 (=WO 2014/106841), the use of pentabromobenzyl
halide as alkylating reagent in Friedel-Crafts alkylation reaction
of low molecular weight aromatic compounds such as
alkyl-substituted benzene (e.g., toluene, xylene, ethylbenzene) and
diphenylalkane has been illustrated.
[0007] We have now found that the --CH.sub.2C.sub.6Br.sub.5 group
can be incorporated into aromatic rings-containing polymers via a
synthetic pathway based on an electrophilic aromatic C-alkylation
(also known as Friedel-Crafts alkylation), to produce bromine-rich
polymers useful as flame retardants. The present invention thus
provides a polymer comprising six-membered aromatic rings, either
in the form of side chains (like in polystyrene) or as part of its
backbone chain (like in poly (phenylether)), characterized in that
pendent --CH.sub.2C.sub.6Br.sub.5 groups are attached to at least a
portion of said six-membered aromatic rings of the polymer, with a
carbon ring atom being bonded to the aliphatic (benzylic) carbon of
said --CH.sub.2C.sub.6Br.sub.5 pendent group. The pentabromobenzyl
group-containing polymers of the invention have high molecular
weight, preferably not less than 1,800, e.g., not less than 3,500
(e.g., >6,000), their bromine content is preferably not less
than 60%, they are insoluble in water and they are also quite
stable against hydrolysis and/or decomposition.
[0008] It should be noted that the invention pertains also to
copolymers having two or more different types of repeat units,
provided, of course, that at least one of said repeat units
contains an aromatic ring with a --CH.sub.2C.sub.6Br.sub.5 pendent
group bonded through its benzylic carbon to a carbon atom of the
aromatic ring in said at least one repeat unit.
[0009] The polymers of the invention fall into two broad
categories: (I) polymers where the aromatic rings (bearing the
--CH.sub.2C.sub.6Br.sub.5 moiety) constitute side groups, and (II)
polymers where the aromatic rings (bearing the
--CH.sub.2C.sub.6Br.sub.5 groups) constitute part of the polymer
backbone chain, as illustrated more specifically by Formulas I and
II, respectively:
##STR00002##
[0010] In the polymer of Formula I, the benzene ring bearing
--CH.sub.2C.sub.6Br.sub.5 group(s) constitutes a side group; R is
Br or a linear or branched aliphatic chain, k is independently an
integer from 0 to 4, preferably 0 or 1, y is an integer from 1 to
(5-k), A=null, ethylene --CH.sub.2CH.sub.2--, butylene
--CH.sub.2CH.dbd.CHCH.sub.2--; propylene --CH(CH.sub.3)CH.sub.2--;
isoprene --CH.sub.2--CH.dbd.C(CH.sub.3)CH.sub.2--, and n and m are
the number of units in the polymer chain (e.g., in Formula I,
3.ltoreq.n.ltoreq.1000 and m=0 or 0.1.ltoreq.m.ltoreq.0.8n; in
Formula II, 3.ltoreq.n.ltoreq.1000).
[0011] In the polymer of Formula II, the benzene ring bearing
--CH.sub.2C.sub.6Br.sub.5 group(s) constitutes part of the backbone
chain; X=null, O, S, CH.sub.2, CH.sub.2CH.sub.2, and n is the
number of units in the polymer chain.
[0012] It should be noted that the representation of the polymers
of the invention by the conventional notation --[--B--]-n is not
intended to imply that each and every unit in the polymer contains
a pendent --CH.sub.2C.sub.6Br.sub.5 group.
[0013] The polymer compounds of the invention are prepared by
reacting pentabromobenzyl halide, especially pentabromobenzyl
bromide (chemically named
1-(bromomethyl)-2,3,4,5,6-pentabromobenzene and abbreviated herein
PBBBr) with a polymer starting material which comprises at least
one six-membered aromatic ring in its repeat unit, as set out
above, in the presence of a suitable Friedel-Crafts catalyst (Lewis
acids) such as AlCl.sub.3, AlBr.sub.3, GaCl.sub.3, FeCl.sub.3,
SnCl.sub.4, SbCl.sub.3, ZnCl.sub.2, CuCl.sub.2 and HF, or a mixture
thereof. The use of AlCl.sub.3, either alone or in combination with
one or more other catalysts, especially SnCl.sub.4, is preferred.
For example, a mixture consisting of AlCl.sub.3 and SnCl.sub.4, in
1:3-3:1 molar ratio, e.g., around 1:1, has been successfully used
to catalyze the reaction.
[0014] Thus, another aspect of the invention is a process for
preparing bromine-containing polymers, comprising a Friedel-Crafts
alkylation reaction of pentabromobenzyl halide
(HaICH.sub.2C.sub.6Br.sub.5, wherein HaI indicates halide such as
chloride or bromide) with a polymer reactant having one or more
six-membered aromatic ring(s) in its repeat unit, wherein said
reaction takes place in a solvent in the presence of at least one
Friedel-Crafts catalyst. The so-formed products (Formulas I and II)
are characterized by the presence of bonds between carbon ring
atoms of the aromatic rings of the polymer, and the benzylic carbon
of the pentabromobenzyl groups.
[0015] Regarding the pentabromobenzyl bromide starting material, it
is commercially available (e.g., from ICL-IP) or it can be prepared
by methods known in the art (e.g., U.S. Pat. Nos. 6,028,156 and
7,601,774), according to a route of synthesis involving the
aromatic bromination of toluene, for example in halogenated
solvent(s), using elemental bromine, in the presence of a Lewis
acid catalyst, e.g. AlCl.sub.3, to form pentabromotoluene
(abbreviated herein 5-BT), which is then brominated at the benzylic
carbon using elemental bromine and a radical source e.g.
azobisisobutyronitrile, as illustrated by the following scheme (see
U.S. Pat. No. 7,601,774):
##STR00003##
[0016] Regarding the starting material which undergoes the aromatic
substitution reaction, namely, electrophilic aromatic C-alkylation
according to the invention, it is a polymer comprising an aromatic
ring in its repeat unit (or in at least one of its repeat units, in
the case of a copolymer starting material). Preferably, the polymer
starting material is represented by formulas III or IV:
##STR00004##
[0017] In Formula III, R is a linear or branched aliphatic chain or
bromine, k is independently an integer from 0 to 4, preferably 0 or
1, A=null, ethylene --CH.sub.2CH.sub.2--, butylene
--CH.sub.2CH.dbd.CHCH.sub.2--; propylene --CH(CH.sub.3)CH.sub.2--;
or isoprene --CH.sub.2--CH.dbd.C(CH.sub.3)CH.sub.2--, n and m are
the number of repeat units in the polymer chain.
[0018] In formula IV, X=null, O, S, CH.sub.2, CH.sub.2CH.sub.2, and
n is the number of repeat units in the polymer chain.
[0019] Exemplary starting materials of formula III include:
[0020] Polystyrene, where k=0, A=null and m=0;
[0021] Styrene copolymers, such as poly(styrene-co-ethylene), where
k=0 and A is --CH.sub.2CH.sub.2--; poly(styrene-co-butadiene),
where k=0 and A is --CH.sub.2CH.dbd.CHCH.sub.2--, (CAS 9003-55-8);
and poly(styrene-co-isoprene), where k=0 and A is
--CH.sub.2--CH.dbd.C(CH.sub.3)CH.sub.2--, (CAS 250038-32-8).
[0022] Exemplary starting materials of formula IV include
poly(phenyl ether), where X.dbd.O.
[0023] The Friedel-Crafts alkylation reaction according to the
invention takes place in a solvent or in a mixture of solvents,
e.g., in a halogenated aliphatic hydrocarbon which is preferably
selected from the group consisting of dichloromethane (DCM),
dibromomethane (DBM), bromochloromethane and dichloroethane (DCE).
The molar ratio between the polymer starting material and
HaICH.sub.2C.sub.6Br.sub.5 is suitably adjusted to satisfy the
desired degree of substitution on the aromatic ring(s) of said
polymer starting material. In general, it is desired to attach not
less than one --CH.sub.2C.sub.6Br.sub.5 group to each six-membered
aromatic ring present in the polymer starting material. The amount
of the catalyst, e.g. AlCl.sub.3 or a mixture of catalysts, is
preferably between 0.5% wt/wt and 2% wt/wt relative to the
HaICH.sub.2C.sub.6Br.sub.5 (e.g., PBBBr amount). The reaction is
run under anhydrous conditions.
[0024] A reaction vessel is charged with a solvent, the polymer
starting material (e.g., polystyrene), HaICH.sub.2C.sub.6Br.sub.5
(e.g., PBBBr) and the catalyst(s). The reactants are dissolved
under heating, following which the catalyst is added. The polymer
starting material and HaICH.sub.2C.sub.6Br.sub.5 may be fed either
simultaneously or successively to the reaction mixture. For
example, in some cases it may be more expedient first to dissolve
the polymer starting material in the solvent, and on formation of a
clear solution, to proceed with the addition of the
HaICH.sub.2C.sub.6Br.sub.5 (e.g., PBBBr) to the solution, or
addition of the polymer solution to the HaICH.sub.2C.sub.6Br.sub.5.
The reaction reaches completion at a temperature of not less
40.degree. C., e.g. from 40.degree. C-90.degree. C., more
specifically from 60.degree. C-90.degree. C. In general, the
reaction time is from 2 to 8 hours. The Friedel-Crafts alkylation
reaction is accompanied by the generation of hydrogen bromide. The
end of the reaction is indicated by either the complete consumption
of the PBBBr (its disappearance can be determined by gas
chromatography analysis) or by the cessation of hydrogen bromide
evolution.
[0025] The product is isolated from the reaction mixture by means
of conventional techniques. The reaction mixture is repeatedly
washed with water, aqueous sodium bisulfite (SBS) or alkaline
solutions (e.g., sodium carbonate or sodium hydrogen carbonate),
whereby excess catalyst is destroyed. In the event that the polymer
product does not spontaneously precipitate from the halogenated
aliphatic hydrocarbon reaction solvent, then its precipitation can
be induced by combining the reaction mixture with a non-solvent
i.e., a solvent in which the product is essentially insoluble.
Polar solvents such as acetone and lower alcohols such as
isopropanol, which are sufficiently miscible with halogenated
aliphatic hydrocarbon, are useful as non-solvents. On cooling, the
polymer product precipitates from mixtures of halogenated aliphatic
hydrocarbon and acetone or isopropanol. The polymer product is
collected by filtration, and optionally washed and dried.
[0026] The invention also relates to the use of pentabromobenzyl
halide HaICH.sub.2C.sub.6Br.sub.5 (e.g., PBBBr) as an alkylation
reagent in a Friedel-Crafts alkylation of a polymer having an
aromatic ring-containing repeat unit, such as those identified by
Formulas III and IV. Preferred polymers starting materials are
polystyrene grades with weight average molecular weight from 170000
to 350000 and polyphenylether grades with weight average molecular
weight from 400 to about 350000.
[0027] In a preferred embodiment, the invention provides a process
comprising charging a reaction vessel with a solvent (e.g.,
halogenated aliphatic hydrocarbon), a polymer starting material
selected from the group consisting of polystyrene and
poly(phenylether), pentabromobenzyl halide
HaICH.sub.2C.sub.6Br.sub.5 (e.g., PBBBr) and one or more catalysts
used for Friedel-Crafts alkylation, allowing the Friedel-Crafts
alkylation to reach completion and recovering bromine-containing
polymer product, i.e., with pendent --CH.sub.2C.sub.6Br.sub.5
groups. Preferably, the number of moles of
HaICH.sub.2C.sub.6Br.sub.5 used is the reaction is not less than
the total number of moles of the aromatic rings in the polymer
starting material. For example, if a grade of polystyrene with an
weight average molecular weight of about 200,000 is used, then the
average number of repeat units in the polymer chain is
approximately 2000 (as the molecular weight of the repeat unit of
polystyrene is around 100). Thus, not less than one mol of
HaICH.sub.2C.sub.6Br.sub.5 would be used per 0.0005 mol of the
polystyrene starting material.
[0028] Preferred bromine-containing polymers of the invention are
those of Formula I, with k=0, m=0 and y=1, as represented by
Formula V:
##STR00005##
[0029] Pentabromobenzyl-substituted polystyrene provided by the
invention is characterized by bromine content of not less than 60%,
e.g., from 65 to 70% by weight. The thermal stability profile of
preferred pentabromobenzyl-substituted polystyrene of the
invention, as indicated by thermogravimetric analysis (TGA), which
measures the weight loss of a sample as sample temperature is
increased, is typically as follows:
TABLE-US-00001 temperature T1 .gtoreq. 360.degree. C. T2 .gtoreq.
370.degree. C. T3 .gtoreq. 380.degree. C. % weight loss 2.0 5.0
10.0
[0030] Other preferred bromine-containing polymers of the invention
are those of Formula II, with X.dbd.O and y=2, as shown by Formula
VI:
##STR00006##
[0031] Pentabromobenzyl-substituted polyphenylether provided by the
invention is characterized by bromine content of not less than 70%
e.g., from 70 to 75% by weight. The thermal stability profile of
preferred pentabromobenzyl-substituted polyphenylether of the
invention is typically as follows:
TABLE-US-00002 temperature T1 .gtoreq. 345.degree. C. T2 .gtoreq.
355.degree. C. T3 .gtoreq. 365.degree. C. % weight loss 2.0 5.0
10.0
[0032] Especially preferred bromine-containing polymer of the
invention is pentabromobenzyl-substituted polystyrene with bromine
content from 65 to 70% by weight, showing 5% weight loss at a
temperature equal to or higher than 370.degree. C. (preferably
>375.degree. C.) and/or 10% weight loss at a temperature higher
than 380.degree. C. (preferably >385.degree. C.), when subjected
to TGA at heating rate of 10.degree. C./min. Bromine content of the
product is measured by the Parr Bomb method, involving the
decomposition of bromine-containing organic compounds to give
bromides, followed by argentometric titration, as described further
below. The experimental results reported below indicate that
pentabromobenzyl-substituted polystyrene is successfully added to
plastic materials to reduce their flammability.
[0033] It is possible to incorporate additional bromine atoms into
the polymers of the invention by subjecting the bromine-containing
polymers produced by the Friedel-Crafts alkylation to a bromination
reaction (e.g., with elemental bromine). One specific embodiment of
the invention is therefore concerned with a process for preparing
bromine-containing polymers, comprising:
[0034] (i) a Friedel-Crafts alkylation reaction of pentabromobenzyl
halide with a polymer reactant having one or more six-membered
aromatic ring(s) in its repeat unit, wherein said reaction takes
place in a solvent in the presence of at least one Friedel-Crafts
catalyst, to obtain pentabromobenzyl-substituted polymer; and
[0035] (ii) subjecting the so-formed pentabromobenzyl-substituted
polymer to bromination reaction.
[0036] The bromination reaction may also take place in halogenated
hydrocarbon, or a mixture of halogenated hydrocarbons, such as
those used for the alkylation reaction. The reaction vessel is
charged with the solvent(s) and pentabromobenzyl-substituted
polymer (e.g., pentabromobenzyl-substituted polystyrene). Elemental
bromine and a suitable catalyst (e.g., one or more Lewis acid
catalysts as identified above, especially AlCl.sub.3 and mixtures
thereof with other catalysts) are charged to the reaction vessel.
Elemental bromine is gradually added to the reaction vessel in an
amount sufficient to provide the degree of bromination sought,
e.g., one or two bromine atoms per aromatic ring in the polymer.
The completion of the bromination reaction is indicated by the
cessation of the HBr evolution. The product is recovered by
conventional methods. In this way it is possible to produce
bromine-containing polymer of Formula I, with the benzene rings
bearing --CH.sub.2C.sub.6Br.sub.5 group(s) and also bromine atoms
(i.e., R is Br and k=1 or 2), with bromine content exceeding 70%
(from 70 to 75% by weight).
[0037] Thus, the bromine-rich polymers of the invention are useful
as flame retardant agents in a flammable material. Accordingly,
another aspect of the present invention is a flame-retarded
composition which comprises a flammable material and the novel
polymer of the invention. For example, the bromine-containing
polymers of the invention can be used to reduce the flammability of
polyamide, polypropylene and acrylonitrile-butadiene-styrene
(ABS).
[0038] A flame-retarded composition of the invention comprises an
effective flame-retarding amount of the novel bromine-containing
polymer of the invention, e.g., the compounds of Formula I and II,
and specifically, V and VI. The concentration the
bromine-containing polymer of the invention in the plastic
formulation is adjusted to secure a bromine content of least 5 wt
%, and preferably at least 10 wt %, for example, from 10 to 25% by
weight, and more specifically, from 10 to 20% by weight (relative
to the total weight of the flame-retarded plastic formulation).
[0039] Other conventional additives may also be included in the
formulation. For example, an inorganic compound (typically a metal
oxide) capable of cooperating with the novel bromine-containing
polymer is preferably also incorporated into the formulation. A
preferred example of a suitable inorganic compound, which is
generally considered as an "inorganic synergist", is antimony
trioxide.
[0040] Specifically, the novel bromine-containing polymers of the
invention display good activity in polyamide. Polyamide-based
composition of the invention comprises at least 30% polyamide,
e.g., between 40% and 70% wt %. The polyamide formulation further
comprises reinforcing fillers, namely, glass fibers, which are
typically pre-coated prior to their use by methods known in the art
in order to improve their compatibility with the polyamide matrix.
Such modified forms of glass fibers are available in the market,
e.g., GF Chop Vantage 3660 from PPG. The glass fibers comprise
filaments with diameters in the range from 2.mu. to 20.mu., and are
applied in the form of pieces with lengths in the range from 2 to
10 mm, e.g., from 3 to 4.5 mm. For example, the major constituents
of glass fibers applied for reinforcing polyamide are
alumino-borosilicates; such a type of glass is known as E-glass.
The concentration of the glass fibers is from 5% to 40% of the
total weight of the polyamide composition.
[0041] In addition to the polyamide, the reinforcing fillers, the
bromine-containing polymer (e.g., compounds of Formula I or II) and
antimony trioxide, the polyamide formulation of this invention may
further contain lubricants, antioxidants (e.g., of a hindered
phenol or phosphite type), pigments, UV stabilizers and heat
stabilizers. The concentration of each of the conventional
additives listed above is typically between 0.05 and 10 wt %.
[0042] The polyamide compositions are produced by melt-mixing the
components, e.g., in a co-kneader or twin screw extruder, wherein
the mixing temperature is in the range from 200 to 300.degree. C.
For example, the polyamide, the bromine containing flame retardant
and the conventional additives (with the exception of the glass
fibers) are dry blended and the blend is fed to the extruder
throat. The glass fibers are the last to be added, i.e.,
downstream.
[0043] Preferred polyamide compositions of the invention comprise
100 parts-by-weight of polyamide (e.g., polyamide 6,6); from 40 to
70 parts-by-weight of glass fibers; from 5 to 50 parts-by-weight of
pentabromobenzyl-substituted polystyrene of Formula V; and from 3
to 15 parts-by-weight of an inorganic synergist (e.g.,
Sb.sub.2O.sub.3).
[0044] The novel bromine-containing polymers of the invention also
demonstrate good activity in reducing the flammability of
polypropylene. Polypropylene composition of the invention
preferably comprises a polypropylene copolymer in an amount of not
less than 50 wt % (relative to the total weight of the
composition), e.g., from 50 to 85 wt %, more specifically from 50
to 70 wt %. Suitable polypropylene impact copolymers which can be
used in the present invention can be in the form of block
copolymers comprising a first block (or phase), which is
essentially the polypropylene homopolymer component and a second
block (or phase), which is an ethylene-propylene copolymer
component. A polypropylene impact copolymer is produced by means of
sequential polymerization reactions under conditions known in the
art. The first reaction produces the homopolymer component and the
second reaction produces the copolymer component. Thus, the
copolymer component is chemically incorporated within the matrix of
the homopolymer component. Different grades of polypropylene impact
copolymers in the form of block copolymers are commercially
available (Carmel Olefins, Israel, under the name Capilene.RTM. SE
50E, TR 50 and SL 50). Impact modified polypropylenes can be
prepared by admixing a polypropylene homopolymer and a rubber. The
compounds of the invention can be used to reduce the flammability
of either filler-free or filler-containing polypropylene-based
formulations.
[0045] Preferred polypropylene compositions of the invention
comprise 100 parts-by-weight polypropylene copolymer; from 5 to 50
parts-by-weight pentabromobenzyl-substituted polystyrene of Formula
V and from 2 to 20 parts-by-weight of an inorganic synergist (e.g.,
Sb.sub.2O.sub.3). Filler-containing polypropylene further comprises
from 5 to 25 parts-by-weight talc, added either in a powder form or
in the form of masterbatch pellets.
[0046] ABS compositions of the invention preferably comprise not
less than 50 wt % ABS (relative to the total weight of the
formulation), e.g., from 50 to 85 wt % ABS. The term ABS refers in
the context of the present invention to copolymers and terpolymers
that include the structural units corresponding to (optionally
substituted) styrene, acrylonitrile and butadiene, regardless of
the composition and method of production of said polymers.
Characteristics and compositions of ABS are described, for example,
in the Encyclopedia of Polymer Science and Engineering, Volume 16,
pages 72-74 (1985). ABS with MFI between 1 and 50 g/10 min
(measured according to ISO 1133 at 220.degree. C./10 kg) are
used.
[0047] The ABS formulation according to the present invention also
includes one or more anti-dripping agents such as
polytetrafluoroethylene (abbreviated PTFE) in a preferred amount
between 0.025 and 0.4 wt %, more preferably between 0.025 and 0.3
wt %, and even more preferably between 0.05 and 0.2 wt %. PTFE is
described, for example, in U.S. Pat. No. 6,503,988.
[0048] The plastic formulations set forth above are readily
prepared by methods known in the art. The various ingredients of
the formulation are blended together, according to their respective
amounts. The ingredients may be first dry blended using suitable
mixing machines, such as Henschel mixer. The resulting mixture may
then be processed and compounded to form homogeneous pellets, for
example, by using a twin screw extruder. The pellets obtained are
dried, and are suitable for feed to an article shaping process such
as injection molding. Other blending and shaping techniques can
also be applied. Articles molded from the polymer formulations form
another aspect of the invention.
EXAMPLES
Methods
[0049] The TGA analysis was performed by a Mettler-toledo
instrument model 850. .about.10 mg sample were heated in aluminum
oxide crucible from 35.degree. C. to about 700.degree. C. with
heating rate of 10.degree. C./min in nitrogen atmosphere.
[0050] Bromine content of the compounds is measured by the Parr
Bomb method. The sample (.about.0.08-0.12 g) is placed in a
peroxide bomb vessel. Sucrose (0.5 g) is added and the full dipper
of sodium peroxide is also added. The sample is subjected to
oxidizing with sodium peroxide while a burner flame is applied to
the bottom of the bomb; the bomb is heated up to about 200.degree.
C. and the burner is then turned off. The bomb is placed in cold
water (2 liters). Gaseous products are absorbed by the alkaline
mixture and are retained within the bomb, mostly in the form of
sodium bromide. The content of the bomb is then combined with warm
water. Hydrazine sulfate is added to destroy residual sodium
peroxide. Nitric acid is added in portions, until the solution is
completely neutralized and becomes acidic. The solution is cooled
to room temperature and then subjected to titration with AgNO.sub.3
(0.1 N) to determine bromine content.
Example 1
Reaction of Polystyrene with PBBBr using AlCl.sub.3 and
SnCl.sub.4
[0051] DBM (1.8 L) and polystyrene with MW of 170000-350000 (104.15
g) were placed in a 2 L reactor fitted with a mechanical stirrer,
thermometer, condenser, HBr trap and N.sub.2 inlet. The mixture was
heated to 66.degree. C. to give a clear solution. PBBBr (565.5 g)
was then dissolved in the solution. AlCl.sub.3 (3.1 g) and
SnCl.sub.4(4.8 g) were added and the mixture was heated to
84.degree. C., following which the vigorous evolution of HBr
started. The mixture was heated at 80.degree. C. for about 6 hours
until the PBBBr disappeared (by GC or HPLC). The reaction mixture
was washed three times: with water (1.5 L), saturated NaHCO.sub.3
solution (1.5 L) to give pH=7, and again with water (1.5 L), taking
30 minutes for each washing. After that, the reaction mixture was
added dropwise to acetone (6 L) to induce precipitation. The
reaction mixture was cooled to 20.degree. C. and the solid was
filtered off and dried in an oven at 105.degree. C. under reduced
pressure for 12 hours, to give 509 g, corresponding to an
.about.86% yield, based on PBBBr. According to elemental analysis,
the content of bromine is about 68%, corresponding to about one
PBBBr molecule per aromatic ring. The TGA profile of the product is
tabulated below:
TABLE-US-00003 Temperature T1 = 365.degree. C. T2 = 381.degree. C.
T3 = 391.degree. C. % weight loss 2.0 5.0 10.0
Example 2
Reaction of Polystyrene with PBBBr using AlCl.sub.3
[0052] The procedure of Example 1 was repeated, but using PBBBr
(27.1 g), polystyrene (10.0 g), AlCl.sub.3 (0.2 g) and
dichloroethane (100 ml) as the solvent. The weight of the product
was 24.0 g, corresponding to 72% yield, based on PBBBr. The content
of bromine is about 60.0%.
Example 3
Reaction of Polyphenylether with PBBBr
[0053] Polyphenylether [Santovac 7, available from Santolubes LLC,
MW.about.450 (30 g)], PBBBr (366.4 g) and DBM (700 ml) were placed
in a 1 L reactor fitted with a mechanical stirrer, thermometer,
condenser, HBr trap and N.sub.2 inlet. The mixture was heated to
70.degree. C. and AlCl.sub.3 (3.5 g) was added by portions. The
mixture was stirred at 90.degree. C. until the PBBBr disappeared
(5-6 h). The reaction mixture was washed at 50.degree. C. with
water (250 ml) and SBS (2.5 ml, .about.28%), water (250 ml), 5%
Na.sub.2CO.sub.3 (250 ml) and water (250 ml), taking 20 minutes for
each washing. The solvent (.about.150 ml) was evaporated under
reduced pressure. The remainder, heated at 40-50.degree. C., was
added dropwise to IPA (450 ml) at 50.degree. C., over 1 h, under
vigorous stirring. The mixture was stirred at 50.degree. C. for 1 h
then cooled to 18.degree. C. The solid was filtered off and washed
with IPA (150 ml) on the filter. The solid was dried in the oven at
105.degree. C., and at 150.degree. C. under reduced pressure, for 3
and 7 hours respectively, to give a white powder product (318 g,
corresponding to .about.92% yield, based on PBBBr). The content of
bromine is about 75.0%. The TGA profile of the product is tabulated
below:
TABLE-US-00004 Temperature T1 = 351.degree. C. T2 = 368.degree. C.
T3 = 375.degree. C. % weight loss 2.0 5.0 10.0
Example 4
Bromination of the Product from Example 1
[0054] DBM/DCM (1495 g/96 g) and product of Example 1 (191.3 g)
were placed in a 2 L reactor fitted with a mechanical stirrer, a
dropping funnel, thermometer, condenser, HBr trap and N.sub.2
inlet. The mixture was heated to 60.degree. C. to give a clear
solution. Br.sub.2 (38.2 g) was then added dropwise to the solution
over 0.5 h. AlCl.sub.3 (1.0 g) and SnCl.sub.4 (2.0 g) were added
and the mixture was heated to 65.degree. C. and additional Br.sub.2
(76.4 g) was added dropwise, following which the vigorous evolution
of HBr started. The mixture was heated at 65.degree. C. for about 6
hours until the HBr evaluation was observed (by titration). The
reaction mixture was washed: with water (1.0 L), saturated
NaHCO.sub.3 solution (1.0 L) and again with water (1.0 L) to give
pH=7, taking 30 minutes for each washing.
[0055] After that, the reaction mixture was added dropwise to
isopropanol (1.5 L) to induce precipitation. The reaction mixture
was cooled to 20.degree. C. and the solid was filtered off and
dried in an oven at 105.degree. C. under reduced pressure for 12
hours, to give 218 g, corresponding to an -89% yield.
[0056] According to analysis, the content of bromine is about 72%,
corresponding to about two bromine atoms per aromatic ring. The TGA
profile of the product is tabulated below:
TABLE-US-00005 Temperature T1 = 267.degree. C. T2 = 330.degree. C.
T3 = 375.degree. C. % weight loss 2.0 5.0 10.0
[0057] In the studies reported in the following examples, the
ability of pentabromobenzyl-substituted polystyrene of Example 1 to
reduce the flammability of different thermoplastics was evaluated.
Test specimens were prepared and subjected to the following
tests:
Flammability Test
[0058] The flammability test was carried out according to the
Underwriters-Laboratories standard UL 94, applying the vertical
burn on specimens of 0.8 mm or 1.6 mm thickness.
[0059] Mechanical Properties
[0060] Impact strength was measured using the Izod notched test
according to ASTM D-256-81, using pendulum impact tester type 5102
(Zwick).
[0061] Tensile properties (tensile strength, tensile modulus,
elongation at break) were measured in Zwick 1435 material testing
machine according to ASTM D-638-95 (v=5 mm/min).
[0062] Other Properties
[0063] HDT (heat distortion temperature; this is the temperature at
which a polymer sample deforms under a specific load) was measured
according to ASTM D-648-72 with load of 1820 kPa and heating rate
of 120.degree. C./hour; the instrument is HDT/Vicat-plus from
Davenport, Lloyd instruments.
[0064] MFI (melt flow index) was determined according to ASTM D1238
(230.degree. C./2.16 kg for PP; 250.degree. C./1.2 kg for
polyamide); the instrument is Meltflixer 2000 from Thermo Hake.
Example 5 (Comparative) and Example 6 (of the Invention)
V-0 Rated Polyamide 6,6 Formulation
[0065] In this set of examples, pentabromobenzyl-substituted
polystyrene of Example 1 was tested to evaluate its ability to
reduce the flammability of polyamide 6,6. For the purpose of
comparison, corresponding formulation was also prepared, where the
flame retarding agent was another bromine-containing polymer
(FR-803P; brominated polystyrene commercially available from
IC-IP).
Ingredients Used to Prepare the Compositions
[0066] The materials employed in the experimental work are set out
in Table 1 (the abbreviation "FR" indicates flame retardant):
TABLE-US-00006 TABLE 1 Product (manufacturer) description function
P-50FL (Nilit) Polyamide 66 Plastic matrix GF Chop Vantage Glass
fibers Reinforcing agents 3660 (PPG) FR-803P (ICL-IP) Brominated
polystyrene FR Product of Pentabromobenzyl-substituted FR Example 1
polystyrene AO M-0112 Antimony trioxide masterbatch FR-synergist
(Kafrit) which contains 80% by weight Sb.sub.2O.sub.3 Ca stearate
(Ciba) Calcium Stearate Lubricant Acrawax C Nitrogen-containing,
hindered Antioxidant & heat (Lonza) phenol stabilizer Irganox
1171B N,N' ethylene bisstearamide Antioxidant & heat (Ciba)
stabilizer
Preparation of Polyamide Compositions and Test Specimens
[0067] The ingredients were compounded in a twin-screw co-rotating
extruder (Berstorff ZE25) with L/D=32. The polyamide, the
bromine-containing flame retardant and all other additives - with
the exception of glass fibers--were weighed and mixed, and the
resultant blend was fed into the main feeding port of the extruder.
The glass fibers were fed into the fifth section of the extruder
via lateral side feeding. A set temperature profile of
250-260-265-265-265-270-275-280.degree. C. was employed. The screw
speed was 350 rpm, and the feeding rate was 12 kg per hour.
[0068] The extrudates obtained were pelletized in pelletizer 750/3
(Accrapac Systems Limited). The resultant pellets were dried in a
circulating air oven at 120.degree. C. for four hours and at
80.degree. C. in a vacuum oven overnight.
[0069] The dried pellets were injection molded into test specimens
using Allrounder 500-150 (Arburg). The conditions of the injection
molding are set out in Table 2.
TABLE-US-00007 TABLE 2 PARAMETER UNITS Set values T.sub.1 (Feeding
zone) .degree. C. 265 T.sub.2 .degree. C. 270 T.sub.3 .degree. C.
275 T.sub.4 .degree. C. 280 T.sub.5 (nozzle) .degree. C. 285 Mold
temperature .degree. C. 85 Injection pressure bar 1200 Holding
pressure bar 500 Back pressure bar 80 Holding time sec 2 Cooling
time sec 13 Filling volume ccm 19 (portion) Injection speed ccm/sec
35 Switch over point [ccm] 12
[0070] The specimens produced were conditioned at 23.degree. C. for
a week and were then subjected to a series of tests. The
compositions produced and the results of the tests are set out in
Table 3.
TABLE-US-00008 TABLE 3 Examples and FR used Example 5 Example 6
(comparative) (invention) Composition Polyamide 66 (P-50FL) 43.8
44.3 Glass fibers (GF Chop Vantage 3660) 30.0 30.0 Flame retardant
19.5 (Brominated polystyrene FR-803P) Flame retardant 19.1
(Pentabromobenzyl-substituted polystyrene of Example 1)
Sb.sub.2O.sub.3 (as M-0112; containing 80% 6.0 6.0 Sb.sub.2O.sub.3)
Antioxidant & heat stabilizer (Acrawax C) 0.2 0.2 Antioxidant
& heat stabilizer (Irganox 0.2 0.2 B1171) Lubricant (calcium
stearate) 0.2 0.2 Bromine (calculated wt %) 13.0 13.0
Sb.sub.2O.sub.3 (calculated wt %) 4.8 4.8 properties Flammability
test: UL-94 vertical burning test at 0.8 mm thickness Max flaming
time (s) 1 1 Total flaming time (s) 10 10 Number of specimens
dripped 5 5 Number of specimens igniting cotton 0 0 UL 94 Rating
V-0 V-0 Mechanical properties Izod notched impact (J/m) 96 97
Tensile strength (MPa) 149 137 Tensile modulus (MPa) 10462 10450
elongation at break (%) 3.7 3.5
[0071] The results set out in Table 3 indicate that
pentabromobenzyl-substituted polystyrene and commercial brominated
polystyrene show equally good performance as flame retarding agents
in polyamide. The flammability and mechanical properties of the
exemplified polyamide formulations are comparable.
Example 7-8 (Comparative) and Example 9 (of the Invention)
V-0 Rated Talc-Free Polypropylene Formulations
[0072] Pentabromobenzyl-substituted polystyrene of Example 1 was
tested to evaluate its ability to reduce the flammability of
polypropylene copolymers (talc-free). For the purpose of
comparison, two corresponding formulations was prepared, using
decabromodiphenyl ethane and poly(pentabromobenzyl acrylate) as
flame retarding agents (FR-1410 and FR-1025, respectively; both are
commercially available from ICL-IP). Materials used for preparing
the compositions are tabulated in Table 4.
TABLE-US-00009 TABLE 4 Material (manufacturer) GENERAL DESCRIPTION
FUNCTION PP Capilene SL-50 polypropylene impact copolymer plastic
matrix (Caol) FR 1410 decabromodiphenyl ethane FR FR 1025
poly(pentabromobenzyl acrylate FR Product of
pentabromobenzyl-substituted FR Example 1 polystyrene M0112
Antimony trioxide masterbatch FR synergist (Kafrit) which contains
80% by weight Sb.sub.2O.sub.3 Irganox B 225 50% tris(2,4-ditert-
Antioxidant & (Ciba) butylphenyl)phosphite and 50% heat
stabilizer. pentaerythritol tetrakis[3-[3,5-di- tert-butyl-4-
hydroxyphenyl]propionate]
Preparation of Polypropylene Compositions and Test Specimens
[0073] The compounding was performed in a twin-screw co-rotating
extruder ZE25 with L/D=32. Temperature profile of
120-180-200-200-200-210-220-230.degree. C. was employed. The screw
speed was 350 rpm, and the feeding rate was 12 kg per hour.
[0074] The extrudtaes produced were pelletized in a pelletizer
750/3 from Accrapak Systems Ltd. The resultant pellets were dried
in a circulating air oven at 80.degree. C. for 3 hours. The dried
pellets were injection molded into test specimens (1.6 mm thick)
using Allrounder 500-150 from Arburg as tabulated in Table 5.
TABLE-US-00010 TABLE 5 PARAMETER UNITS Set values T.sub.1 (Feeding
zone) .degree. C. 210 T.sub.2 .degree. C. 215 T.sub.3 .degree. C.
220 T.sub.4 .degree. C. 225 T.sub.5 (nozzle) .degree. C. 230 Mold
temperature .degree. C. 35 Injection pressure bar 1300 Holding
pressure bar 600 Back pressure bar 60 Holding time sec 7 Cooling
time sec 13 Filling volume (portion) ccm 38 Injection speed ccm/sec
35
[0075] The specimens were conditioned for one week at 23.degree.
C., and were subjected to a set of tests. The results are shown in
Table 7.
TABLE-US-00011 TABLE 7 Example 7 8 9 (comparative) (comparative)
(invention) Composition (by weight %) Polypropylene 57.4 57.4 60 FR
1410 28 FR 1025 28 product of Example 1 27.9 Sb.sub.2O.sub.3 (as
M-0112; 14.4 14.4 11.9 containing 80% Sb.sub.2O.sub.3) Irganox B
225 0.2 0.2 0.2 Br content, % calculated 22 20 19.0
Sb.sub.2O.sub.3, % calculated 11.5 11.5 9.5 Properties Flammability
test: UL-94 vertical burning test at 1.6 mm thickness Maximal
flaming time 6 8 9 (sec) Total Flaming time (sec) 17 47 63 Maximal
glow time + 25 35 3 second flaming (sec) Number of specimen 5 5 5
Number of Specimens 4 0 5 dripped Number of cotton 0 0 0 ignition
Rating V-0 V-0 V-0 Mechanical Properties Impact strength (J/m) 34
29 44 Tensile strength (MPa) 21 24 20 Elongation at break (%) 46 7
61 Tensile modulus (MPa) 2010 1725 1478 Other properties HDT
(.degree. C.) 58 85 62 MFI (gr/10 min) 4.8 7.7 4.12
[0076] The results show that pentabromobenzyl-substituted
polystyrene is successfully added to polypropylene copolymer at a
relatively low concentration in comparison to other
bromine-containing flame retarding agents, to pass the UL-94 V-0
flammability test. Pentabromobenzyl-substituted polystyrene of the
invention is able to achieve UL-94 V-0 rating in polypropylene
copolymers at a bromine content of 19% by weight, with the aid of
9.5% by weight antimony trioxide. The comparative brominated flame
retardants tested require higher bromine and antimony trioxide
loading to impart UL-94 V-0 rating to polypropylene copolymers.
Examples 10-12 (of the Invention)
V-1 Rated Talc-Containing Polypropylene Formulations
[0077] The aim of this set of examples is to evaluate the ability
of pentabromobenzyl-substituted polystyrene of Example 1 to reduce
the flammability of talc-containing polypropylene formulations.
Ingredients used to Prepare the Compositions
[0078] The materials used for preparing the polypropylene
compositions are tabulated in Table 8.
TABLE-US-00012 TABLE 8 Component (manufacturer) GENERAL DESCRIPTION
FUNCTION PP Capilene polypropylene impact copolymer plastic SL-50
(Caol) matrix Product of Pentabromobenzyl-substituted FR Example 1
polystyrene M0112 Antimony trioxide masterbatch which FR synergist
(Kafrit) contains 80% by weight Sb.sub.2O.sub.3 Talc MB Talc
masterbatch of IOTALC Filler (Kafrit) IOTALC Talc powder Filler
Irganox B 225 50% tris(2,4-ditert-butylphenyl)phosphite Antioxidant
(Ciba) and 50% pentaerythritol tetrakis[3-[3,5-di- & heat
tert-butyl-4-hydroxyphenyl]propionate] stabilizer.
Preparation of Polypropylene Compositions and Test Specimens
[0079] The ingredients were compounded in a twin-screw co-rotating
extruder (Berstorff ZE25) with L/D=32. Temperature profile of
120-180-200-200-200-210-220-230.degree. C. was employed. The screw
speed was 350 rpm, and the feeding rate was 12 kg per hour.
[0080] The extrudates produced were pelletized in a pelletizer
750/3 from Accrapak Systems Ltd. The resultant pellets were dried
in a circulating air oven at 80.degree. C. for 3 hours.
[0081] The dried pellets were injection molded into test specimens
using Allrounder 500-150 from Arburg according to the parameters
set out in Table 9.
TABLE-US-00013 TABLE 9 PARAMETER UNITS Set values T.sub.1 (Feeding
zone) .degree. C. 210 T.sub.2 .degree. C. 215 T.sub.3 .degree. C.
220 T.sub.4 .degree. C. 225 T.sub.5 (nozzle) .degree. C. 230 Mold
temperature .degree. C. 35 Injection pressure bar 1300 Holding
pressure bar 600 Back pressure bar 60 Holding time sec 7 Cooling
time sec 13 Filling volume (portion) ccm 38 Injection speed ccm/sec
35
[0082] The specimens were conditioned for one week at 23.degree.
C., and were then tested. The compositions and the results of the
tests are set out in Table 10.
TABLE-US-00014 TABLE 10 Example 10 11 12 Composition (by weight %)
Polypropylene 59.6 55.8 49.2 product of Example 1 23.5 26.5 26.5
Sb.sub.2O.sub.3 (as M-0112; containing 80% Sb.sub.2O.sub.3) 6.7 7.5
7.5 IOtalc 10.0 10.0 Talc masterbatch 16.7 Irganox B 225 0.2 0.2
0.2 Bromine content, % calculated 16 18 18.0 Antimony trioxide, %
calculated 5.3 6.0 6.0 Talc, % calculated 10 10 10 Properties
Flammability test: UL-94 vertical burning test at 1.6 mm thickness
Maximal flaming time (sec) 16 19 15 Total Flaming time (sec) -- 73
67 Maximal glow time + second flaming 0 6 28 Number of specimen 2 5
5 Number of Specimens dripped 2 5 5 Number of cotton ignition 2 0 0
Rating V-2 V-1 V-1 Mechanical Properties Impact strength (J/m) ND
32 35 Tensile strength (MPa) ND 21 18 Elongation at break (%) ND 30
55 Tensile modulus (MPa) ND 1924 1616 Other properties HDT
(.degree. C.) ND 62 57 MFI (g/10 min) ND 3.45 3.08
* * * * *