U.S. patent application number 12/009052 was filed with the patent office on 2008-09-11 for flame retardant composition for use in styrenics.
Invention is credited to Steven Bakeis, David W. Bartley, Stephen B. Falloon, Julia E. Holland, Wayne Meyer.
Application Number | 20080221239 12/009052 |
Document ID | / |
Family ID | 39742280 |
Filed Date | 2008-09-11 |
United States Patent
Application |
20080221239 |
Kind Code |
A1 |
Falloon; Stephen B. ; et
al. |
September 11, 2008 |
Flame retardant composition for use in styrenics
Abstract
A method for flame-retarding styrenic resins is disclosed
wherein the method comprises incorporating in compositions an
effective amount of at least one flame retardant compound
comprising both aliphatic and aromatic bromine.
Inventors: |
Falloon; Stephen B.;
(Lafayette, IN) ; Bartley; David W.; (West
Lafayette, IN) ; Holland; Julia E.; (Indianapolis,
IN) ; Meyer; Wayne; (West Lafayette, IN) ;
Bakeis; Steven; (West Lafayette, IN) |
Correspondence
Address: |
Daniel Reitenbach;CHEMTURA CORPORATION
199 Benson Road
Middlebury
CT
06749
US
|
Family ID: |
39742280 |
Appl. No.: |
12/009052 |
Filed: |
January 15, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60905328 |
Mar 7, 2007 |
|
|
|
Current U.S.
Class: |
524/81 |
Current CPC
Class: |
C07C 17/14 20130101;
C08K 5/03 20130101; C08K 5/02 20130101; C07C 17/12 20130101; C08K
5/03 20130101; C08L 25/04 20130101; C08L 25/04 20130101; C08K 5/02
20130101 |
Class at
Publication: |
524/81 |
International
Class: |
C08K 5/03 20060101
C08K005/03; C08K 5/02 20060101 C08K005/02 |
Claims
1. A method for flame-retarding styrenic resins and foamed styrenic
resins comprising incorporating an effective amount of at least one
flame retardant compound comprising both aliphatic and aromatic
bromine.
2. The method of claim 1 wherein the flame retardant compound is
selected from the group consisting of: ##STR00012## wherein
R.sup.1, R.sup.2, R.sup.3, R.sup.5, and R.sup.6 are independently
selected from the group consisting of hydrogen and bromine, and
R.sup.4 is selected from the group consisting of hydrogen, bromine,
and CH.sub.2Br; ##STR00013## wherein R.sup.7 through R.sup.14 are
independently selected from the group consisting of hydrogen and
bromine, R.sup.15 is selected from the group consisting of CH.sub.2
and CHBr, and R.sup.16 is selected from the group consisting of
CH.sub.2, CHBr, and a fused ring; ##STR00014## wherein R.sup.17
through R.sup.26 are independently selected from the group
consisting of hydrogen and bromine, provided that no more than
seven of R.sup.17 through R.sup.26 are bromine; ##STR00015##
wherein R.sup.27 is selected from the group consisting of alkyl,
aryl, alkaryl, and SO.sub.2, R.sup.28 and R.sup.29 are
independently selected from the group consisting of hydrogen and
alkyl, R.sup.30, R.sup.31, R.sup.36, and R.sup.37 are independently
selected from the group consisting of methyl and CH.sub.2Br, and
R.sup.32 through R.sup.35 are independently selected from the group
consisting of hydrogen and bromine; ##STR00016## wherein R.sup.38
through R.sup.42 are independently selected from the group
consisting of hydrogen, bromine, CH.sub.2Br, and alkyl, and
R.sup.43 through R.sup.47 are independently selected from the group
consisting of hydrogen and bromine; and ##STR00017## wherein
R.sup.48 is selected from the group consisting of alkyl, aryl,
alkaryl, and SO.sub.2, R.sup.49 through R.sup.52 are independently
selected from the group consisting of CH.sub.3 and CH.sub.2Br,
R.sup.53 through R.sup.56 are independently selected from the group
consisting of hydrogen and bromine, and R.sup.57 and R.sup.58 are
independently selected from the group consisting of hydrogen and
alkyl; provided that in each of the foregoing structures, there is
at least one aliphatic bromine and at least one aromatic
bromine.
3. The method of claim 1 wherein the flame retardant compound is
selected from the group consisting of: ##STR00018##
4. The method of claim 1 wherein the flame retardant compound is
selected from the group consisting of
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene, 1-bromoethyl
dibromobenzene, 1-bromoethyl tribromobenzene, 1-bromoethyl
tetrabromobenzene, bis-(1-bromoethyl)benzene,
bis-(1-bromoethyl)bromobenzene, bis-(1-bromoethyl)dibromobenzene,
bis-(1-bromoethyl)tribromobenzene,
bis-(1-bromoethyl)tetrabromobenzene, 9,10-dibromo-9,10-dihydro
octabromoanthracene, 9,10-dibromo-9,10-dihydro
septabromoanthracene, 9,10-dibromo-9,10-dihydro
hexabromoanthracene, 9,10-dibromo-9,10-dihydro
pentabromoanthracene, 4-bromomethyl tetrabromobenzyl
2,4,6-tribromophenyl ether, and 4-bromomethyl benzyl
2,4,6-tribromophenyl ether.
5. The method of claim 4 wherein the flame retardant compound is
selected from the group consisting of 1,1
'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene and
9,10-dibromo-9,10-dihydrooctabromo anthracene.
6. The method of claim 5 wherein the flame retardant compound is
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene.
7. The method of claim 1 wherein the flame retardant compound has
an LOI of greater than 26 @ 5 phr and a 5% weight loss based on TGA
analysis of above 215.degree. C.
8. An article of manufacture comprising a styrenic resin
composition or foamed styrenic resin composition wherein said
composition comprises an effective amount of at least one flame
retardant compound comprising both aliphatic and aromatic
bromine.
9. The article of claim 8 wherein the flame retardant compound is
selected from the group consisting of: ##STR00019## wherein
R.sup.1, R.sup.2, R.sup.3, R.sup.5, and R.sup.6 are independently
selected from the group consisting of hydrogen and bromine, and
R.sup.4 is selected from the group consisting of hydrogen, bromine,
and CH.sub.2Br; ##STR00020## wherein R.sup.7 through R.sup.14 are
independently selected from the group consisting of hydrogen and
bromine, R.sup.15 is selected from the group consisting of CH.sub.2
and CHBr, and R.sup.16 is selected from the group consisting of
CH.sub.2, CHBr, and a fused ring; ##STR00021## wherein R.sup.17
through R.sup.26 are independently selected from the group
consisting of hydrogen and bromine, provided that no more than
seven of R.sup.17 through R.sup.26 are bromine; ##STR00022##
wherein R.sup.27 is selected from the group consisting of alkyl,
aryl, alkaryl, and SO.sub.2, R.sup.28 and R.sup.29 are
independently selected from the group consisting of hydrogen and
alkyl, R.sup.30, R.sup.31, R.sup.36, and R.sup.37 are independently
selected from the group consisting of methyl and CH.sub.2Br, and
R.sup.32 through R.sup.35 are independently selected from the group
consisting of hydrogen and bromine; ##STR00023## wherein R.sup.38
through R.sup.42 are independently selected from the group
consisting of hydrogen, bromine, CH.sub.2Br, and alkyl, and
R.sup.43 through R.sup.47 are independently selected from the group
consisting of hydrogen and bromine; and ##STR00024## wherein
R.sup.48 is selected from the group consisting of alkyl, aryl,
alkaryl, and SO.sub.2, R.sup.49 through R.sup.52 are independently
selected from the group consisting of CH.sub.3 and CH.sub.2Br,
R.sup.53 through R.sup.56 are independently selected from the group
consisting of hydrogen and bromine, and R.sup.57 and R.sup.58 are
independently selected from the group consisting of hydrogen and
alkyl; provided that in each of the foregoing structures, there is
at least one aliphatic bromine and at least one aromatic
bromine.
10. The article of claim 8 wherein the flame retardant compound is
selected from the group consisting of: ##STR00025##
11. The article of claim 8 wherein the flame retardant compound is
selected from the group consisting of
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene, 1-bromoethyl
dibromobenzene, 1-bromoethyl tribromobenzene, 1-bromoethyl
tetrabromobenzene, bis-(1-bromoethyl)benzene,
bis-(1-bromoethyl)bromobenzene, bis-(1-bromoethyl)dibromobenzene,
bis-(1-bromoethyl)tribromobenzene,
bis-(1-bromoethyl)tetrabromobenzene, 9,10-dibromo-9,10-dihydro
octabromoanthracene, 9,10-dibromo-9,10-dihydro
septabromoanthracene, 9,10-dibromo-9,10-dihydro
hexabromoanthracene, 9,10-dibromo-9,10-dihydro
pentabromoanthracene, 4-bromomethyl tetrabromobenzyl
2,4,6-tribromophenyl ether, and 4-bromomethyl benzyl
2,4,6-tribromophenyl ether.
12. The article of claim 11 wherein the flame retardant compound is
selected from the group consisting of
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene and
9,10-dibromo-9,10-dihydrooctabromo anthracene.
13. The article of claim 12 wherein the flame retardant compound is
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene.
14. The article of claim 8 wherein the flame retardant compound has
an LOI of greater than 24 @ 5 phr when formulated into the resin in
the range of 2-10 phr and a 5% weight loss based on TGA analysis of
above 200.degree. C.
Description
[0001] I claim the benefit under Title 35, United States Code,
.sctn.119 to U.S. Provisional Application Number 60/905,328; filed
Mar. 7, 2007; entitled New Flame Retardant Composition for use in
Styrenics.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is related to flame retardants. More
particularly, the present invention is related to flame retardants
comprising both aliphatic and aromatic bromine for use with
styrenic resins.
[0004] 2. Description of Related Art
[0005] Styrenic resins are well known in the synthetic organic
polymer art as a class of thermoplastics that offer excellent
mechanical properties as well as good chemical resistance. The
properties that make styrenics useful for many applications as
solid polymers also make them very desirable as foamed polymers. A
number of processes have been developed over the last forty years
to prepare styrenic foams for a variety of applications, some of
which require the use of flame retardants.
[0006] A flame retardant, such as a halogenated organic compound,
is often incorporated into a formulated resin in order to render
the resin resistant to ignition. It is known that brominated
aliphatic compounds, brominated aromatic compounds, and mixtures
thereof have been used in solid and foamed styrenic applications.
Hexabromocyclododecane (HBCD) is one such known aliphatic
brominated flame retardant that has been used in foamed styrenic
applications. HBCD is a highly brominated aliphatic flame retardant
that has unusually high thermal stability, which results in
excellent performance at low loading levels with a minimum effect
on polymer properties.
[0007] Recently there have been concerns about the health and
environmental impact of some flame retardants including HBCD.
Although scientific studies have not necessarily shown significant
risks to human health or the environment, there are ongoing reviews
by various regulatory agencies that may result in reduced usage of
HBCD. In the event that these agencies limit the usage of HBCD,
extruded polystyrene foam and expanded polystyrene foam
manufacturers may be required to choose an alternative flame
retardant, and many may adopt a substitute before any regulatory
mandate. Thus, there exists a need for a flame retardant
alternative to HBCD that is more environmentally friendly and
maintains all of the performance properties of HBCD.
[0008] WO 2007/057900 discloses polybrominated bisaryl compounds
containing bromomethyl or bromomethylene groups, as well as
flameproof polymeric formulations comprising the compounds. These
compounds are said to exhibit good thermal stability and to be
particularly suitable for flame-retarding polystyrene thermoplastic
foams. A process for making the polybrominated bisaryl compounds is
also disclosed.
[0009] WO 2006/008738 discloses a process for the preparation of
highly pure pentabromobenzyl bromide, wherein the benzylic
bromination reaction is carried out in a suitable organic solvent
in the presence of water and wherein the reaction temperature is
such that it is sufficient to activate the initiator but not high
enough to consume a substantial amount thereof.
[0010] WO 2006/013554 discloses a styrenic polymer composition
comprising a flame-retardant effective amount of a compound of
formula (I): (C.sub.6H(.sub.5-n)Y.sub.n)CH.sub.2X, wherein X is Cl
or Br; Y is Cl or Br; and n is an integer between 1 and 5; or a
mixture of two or more of said compounds of formula (I) or their
homologues and derivatives or other Br-FRs.
[0011] GB 1,107,283 discloses a granular expandable polystyrene
composition that contains as a fire-retardant a minor amount of a
compound of formula Ar(Br).sub.m(Cl).sub.nR or
Ar(Br).sub.x(Cl).sub.yOR where Ar is an aryl residue, m is 1-4, n
is 0-2, x is 1 or more, y is 0 or an integer and R is hydrogen, a
straight or branched chain alkyl group which may be halogenated, a
straight or branched chain alkenyl group or a halogenated aryl
group; there being at least 2 nuclear bromine atoms per molecule of
the above compound. The compound may be tetrabromobenzene,
tribromophenol, pentabromophenyl (allyl, ethyl or n-propyl) ether,
an isomer of tribromotoluene or tribromophenyl allyl ether,
chlorodibromotoluene, chlorodibromophenyl allyl ether,
hexabromodiphenyl ether, dibromodiphenyl, dibromonaphthalene;
2,4-dibromo-1-methylnaphthalene; 1,5-dibromoanthracene;
pentabromophenyl dibromopropyl ether, pentabromophenol or
tetrabromochlorophenol. The composition may also contain dicumyl or
di-tert. butyl peroxide, tert. butyl peracetate or cumene
hydroperoxide. The compositions may be made by polymerizing styrene
in the presence of the fire-retardant compound, polystyrene
granules, benzoyl peroxide, water and petroleum ether as expanding
agent and the resulting polymer may be granulated, expanded by
heating in steam and then moulded into a block.
[0012] GB 1,394,787 discloses a flame resistant polystyrene or
styrene-containing copolymer containing hexabromoxylene. There is
further disclosed a self-extinguishing mouldable composition or
moulding comprising polystyrene or a styrene-containing copolymers
and hexabromoxylene in an amount of from 0.5 to 8.0 percent by
weight, based on the total weight of the mould able composition or
moulding.
[0013] EP 0502333 discloses a process for preparing a mixture of
brominated, non-condensed ring polyaromatics, which process
comprises brominating the precursor non-condensed ring polyaromatic
in the presence of a bromination catalyst. The mixture has an
average bromine number of 5.8 to 6.2, more than about 55 GC area
percent of the hexabromo homolog, and a reduced amount of light-end
impurities.
[0014] U.S. Pat. No. 4,024,092 discloses polymer compositions
having enhanced oxygen index values as measured by ASTM Method
D-2863-70, which compositions contain effective amounts of a bromo
or chloro derivative of stilbene.
[0015] U.S. Pat. No. 5,039,729 discloses mixtures of brominated
diphenyl ethanes, such mixtures containing a predominant amount of
hexabromodiphenyl ethane and having an average bromine number,
based upon GC area percent, of from about 6.7 to about 7.3. ABS
based formulations containing such mixtures and articles made from
such formulations are also disclosed.
[0016] U.S. Pat. No. 5,055,235 discloses a process for preparing a
mixture of brominated, non-condensed ring polyaromatics, which
process features multiple bromination temperatures and multiple
catalyst additions for brominating the precursor non-condensed ring
polyaromatic. The mixture has an average bromine number of about 6
to about 8 bromine atoms per molecule, a low melting point range,
and a low amount of light end impurities.
[0017] U.S. Pat. Nos. 5,741,949 and 6,117,371 disclose a process
for producing a brominated, non-fused aromatic composition that
involves a continuous bromination in a continuous, mixed reactor
such as a continuous stirred tank reactor. Bromine and the aromatic
substrate, and optionally a bromination catalyst, are continuously
fed to a reaction zone to form a reaction mixture, and the reaction
mixture is continuously withdrawn from the reaction zone after an
established average residence time. Bromination levels can be
readily controlled by controlling the average residence time of the
reaction mixture within the reaction zone. Preferred continuous
processes also provide mixed, brominated compositions having
product distributions which are substantially broader than that
obtained by batch brominations conducted to achieve the same level
of bromination. Preferred products thus have broad melting ranges
which are advantageous in compounding operations.
[0018] U.S. Pat. No. 5,821,393 discloses a process for the
preparation of an aromatic bromoalkyl-substituted hydrocarbon
compound, in which an alkyl-substituted aromatic hydrocarbon
compound is reacted with a brominating agent in the presence of
water.
[0019] U.S. Pat. No. 6,743,825 discloses an additive mixture said
to be useful as a flame retardant. The mixture is comprised of (i)
a poly(bromophenyl)alkane having in the molecule in the range of 13
to 60 carbon atoms and in the range of two to four aryl groups and
(ii) a poly(bromophenyl)bromoalkane having in the molecule in the
range of 13 to 60 carbon atoms and in the range of two to four aryl
groups, said poly(bromophenyl)bromoalkane being in an amount which
is greater than 25wt %, based on the total weight of the additive
mixture. A process for making the poly(bromophenyl)bromoalkane is
also disclosed.
[0020] The disclosures of the foregoing are incorporated herein by
reference in their entirety.
SUMMARY OF THE INVENTION
[0021] In evaluating alternatives for HBCD, it is important to
maintain the good properties of high efficiency at low usage levels
and high thermal stability. According to the present invention, it
has been found that a single flame retardant compound containing
both aliphatic and aromatic bromine can be used to flame retard
styrenic resins, in particular, foamed styrenic resins. More
surprisingly, the molecules containing aromatic bromine and
benzylic bromine have been found to have the necessary thermal
stability and to be most efficient when compared by lab scale
flammability tests.
[0022] More particularly, the present invention is directed to a
method for flame retarding styrenic resins comprising incorporating
an effective amount of at least one flame retardant compound
comprising both aliphatic and aromatic bromine.
[0023] In another aspect, the present invention is directed to an
article of manufacture comprising a styrenic resin composition or
foamed styrenic resin composition wherein said composition
comprises an effective amount of at least one flame retardant
compound comprising both aliphatic and aromatic bromine. In a
preferred embodiment, in the article the flame retardant compound
has an LOI of greater than 24 @ 5 phr when formulated into the
resin in the range of 2-10 phr and a 5% weight loss based on TGA
analysis of above 200.degree. C.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0024] As noted above, the present invention relates to the use of
compounds comprising both aliphatic and aromatic bromine to flame
retard styrenic resins.
[0025] Examples of target molecules within the scope of the present
invention are shown below:
##STR00001##
wherein R.sup.1, R.sup.2, R.sup.3, R.sup.5, and R.sup.6 are
independently selected from the group consisting of hydrogen and
bromine, and R.sup.4 is selected from the group consisting of
hydrogen, bromine, and CH.sub.2Br;
##STR00002##
wherein R.sup.7 through R.sup.14 are independently selected from
the group consisting of hydrogen and bromine, R.sup.15 is selected
from the group consisting of CH.sub.2 and CHBr, and R.sup.16 is
selected from the group consisting of CH.sub.2, CHBr, and a fused
ring;
##STR00003##
wherein R.sup.17 through R.sup.26 are independently selected from
the group consisting of hydrogen and bromine, provided that no more
than seven of R.sup.17 through R.sup.26 are bromine;
##STR00004##
wherein R.sup.27 is selected from the group consisting of alkyl,
aryl, alkaryl, and SO.sub.2, R.sup.28 and R.sup.29 are
independently selected from the group consisting of hydrogen and
alkyl, R.sup.30, R.sup.31, R.sup.36, and R.sup.37 are independently
selected from the group consisting of methyl and CH.sub.2Br, and
R.sup.32 through R.sup.35 are independently selected from the group
consisting of hydrogen and bromine;
##STR00005##
wherein R.sup.38 through R.sup.42 are independently selected from
the group consisting of hydrogen, bromine, CH.sub.2Br, and alkyl,
and R.sup.43 through R.sup.47 are independently selected from the
group consisting of hydrogen and bromine; and
##STR00006##
wherein R.sup.48 is selected from the group consisting of alkyl,
aryl, alkaryl, and SO.sub.2, R.sup.49 through R.sup.52 are
independently selected from the group consisting of CH.sub.3 and
CH2Br, R.sup.53 through R.sup.56 are independently selected from
the group consisting of hydrogen and bromine, and R.sup.57 and
R.sup.58 are independently selected from the group consisting of
hydrogen and alkyl; provided that in each of the foregoing
structures, there is at least one aliphatic bromine and at least
one aromatic bromine.
[0026] In the foregoing structural formulae, where an R group is:
[0027] a "fused ring", it is a fused ring of from 5 to 8 carbon
atoms; [0028] "alkyl", it is an alkyl group of from 1 to 6 carbon
atoms; [0029] "alkaryl", it is an alkaryl group comprising at least
one alkyl group side chain of from 1 to 6 carbon atoms.
[0030] Examples of specific molecules that can be employed in the
practice of the present invention include, but are not limited to,
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene, 1-bromoethyl
dibromobenzene, 1-bromoethyl tribromobenzene, 1-bromoethyl
tetrabromobenzene, bis-(1-bromoethyl)benzene,
bis-(1-bromoethyl)bromobenzene, bis-(1-bromoethyl)dibromobenzene,
bis-(1-bromoethyl)tribromobenzene,
bis-(1-bromoethyl)tetrabromobenzene, 9,10-dibromo-9,10-dihydro
octabromoanthracene, 9,10-dibromo-9,10-dihydro
septabromoanthracene, 9,10-dibromo9,10-dihydro hexabromoanthracene,
9,10-dibromo-9,10-dihydro pentabromoanthracene, 4-bromomethyl
tetrabromobenzyl 2,4,6-tribromophenyl ether, 4-bromomethyl benzyl
2,4,6-tribromophenyl ether, and the like.
[0031] The most preferred molecules, owing to their balance of
efficiency and thermal stability, are
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene and
9,10-dibromo-9,10-dihydrooctabromo anthracene. The
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene is prepared in
such a away that there are eight major components and several minor
components that average to an aromatic bromine content of 5.5-6
bromine atoms and an average amount of 1.7-1.9 aliphatic bromine
atoms.
[0032] The styrene resins employed in the practice of the present
invention are styrenic polymers, such as polystyrene,
poly-(p-methylstyrene), poly-(.alpha.-methylstyrene), copolymers of
styrene or .alpha.-methylstyrene with dienes or acrylic
derivatives, such as, for example, styrene/butadiene,
styrene/acrylonitrile, styrene/alkyl methacrylate, styrene/maleic
anhydride,
styrene/butadiene/ethylacrylate/styrene/acrylonitrile/methylacrylate,
mixtures of high impact strength from styrene copolymers and
another polymer, such as, for example, from a polyacrylate, a diene
polymer or an ethylene/propylene/diene terpolymer; and block
copolymers of styrene, such as, for example,
styrene/-butadiene/styrene, styrene/isoprene/styrene,
styrene/ethylene/butylene/styrene or styrene/ethylene/propoylene
styrene. Styrenic polymers may additionally or alternatively
include graft copolymers of styrene or .alpha.-methylstyrene such
as, for example, styrene on polybutadiene, styrene on
polybutadiene-styrene or polybutadieneacrylonitrile; styrene and
acrylonitrile (or methacrylonitrile) on polybutadiene and
copolymers thereof; styrene and maleic anhydride or maleimide on
polybutadiene; sytrene, acrylonitrile, and maleic anhydride or
maleimide on polybutadiene; styrene, acrylonitrile, and methyl
methacrylate on polybutadiene, styrene and alkyl acrylates or
methacrylates on polybutadiene, styrene and acrylonitrile on
ethylene/-propylene/diene terpolymers, styrene and acrylonitrile on
polyacrylates or polymethacrylates, styrene and acrylonitrile on
acrylate/butadiene copolymers, and the like.
[0033] Additionally, the styrenic resins can be in the form of
foamed resins. These foamed resins can be comprised of any of the
aforementioned styrenic resins. Processes for making foamed resins
are of two main classes: expanded polystyrene foams (EPS) and
extruded polystyrene foams (XPS). The specific procedures for
forming the foamed resins are well defined in the art.
[0034] The flame retardants of the invention can be conventionally
incorporated into the styrenic materials in flame retardant
amounts. The amount of these flame retardants necessary for flame
retardancy will depend upon the particular brominated substrate
employed and styrenic material involved, as well as other flame
retardants that might be included. Those of ordinary skill in the
art will be readily able to incorporate an amount of the flame
retardant which is necessary to achieve the desired level of flame
retardancy. As is well known, it is often preferred to incorporate
a brominated flame retardant with another flame retardant material,
such as an inorganic compound, e.g. ferric oxide, zinc oxide, zinc
borate, a group V element oxide such as a bismuth, arsenic,
phosphorus or an antimony oxide.
[0035] In addition, foamed resins generally require additional
materials to achieve the desired properties of the foam. These can
include catalysts for polymerization, blowing agents, emulsifiers,
and stabilizers. The exact compositions and quantities of other
additives are known to those skilled in the art.
[0036] When selecting target molecules for screening, molecules
containing only aliphatic, only aromatic, and a mix of aliphatic
and aromatic bromine were considered. Examples of molecules used in
the screening evaluations are shown below:
Aliphatic only:
##STR00007##
##STR00008##
Aromatic only:
##STR00009##
Aliphatic/Aromatic
##STR00010##
[0037] Polymeric Aliphatic/Aromatic
##STR00011##
[0039] In the above, the values of m and n were not rigorously
specified in the analytical data, but approximate numbers would be
m=1 and n=1 in the first molecule and m=10 and n=1 in the second.
This means that there is a higher amount of aliphatic (benzylic)
bromine in the first molecule and a relatively low level of
aliphatic (benzylic) bromine in the second molecule. The LOI data
support the premise that one needs both aliphatic and aromatic
bromine, and that benzylic bromine is even better.
[0040] In the above structures, the notation Br.sub.2 is intended
to mean two bromine atoms, each attached at separate points to the
phenyl ring. Similarly, Br.sub.3, Br.sub.x, and Br.sub.y refer to 3
bromines, x bromines, and y bromines, respectively, where x and y
are independently integers of from 1 to3.
[0041] The target molecule must have an Limiting Oxygen Index (LOI)
of more than 26 @ 5 phr and a 5% wt loss based on TGA analysis of
more than 215.degree. C. in order to be considered comparable to
HBCD in end use EPS and XPS applications. When evaluating molecules
that contain only aliphatic bromine, the molecules were determined
to be efficient as demonstrated by the LOI performance shown above;
however, the molecules did not meet the thermal criteria. Molecules
containing only aromatic bromine were found to be more thermally
stable; however, did not appear to have the necessary efficiency as
determined by LOI.
[0042] Molecules containing both aliphatic and aromatic bromine
were found to have the best balance of efficiency and thermal
stability. It was surprisingly found that molecules containing
aromatic bromine and benzylic bromine have the best balance of
efficiency and thermal stability. This is demonstrated by the
series of dibromostyrene molecules shown above where the LOI
performance drops from 28-31 to 23 when the benzylic bromine is
removed. This observation is also confirmed in the diphenylethane
series shown above wherein, when the benzylic bromine is removed,
the LOI drops from 29 to 25. This series of molecules also
demonstrates the necessity for having aromatic bromine on the
molecule in order to increase the thermal stability of the
molecule.
EXAMPLES
[0043] Typical laboratory hand cast foams were prepared using the
formulations listed below. Lab preparation yielded foams with
comparable densities. The foams were then evaluated by ASTM
D2863-00 and UL-94. ASTM D2863-00 is a test method used to
determine the LOI, which is an indication of flame retardant
effectiveness. Thermal stability is another critical property and
is measured using thernogravimetric analysis (TGA) in a dynamic
mode. Values from this test are reported as the temperature at
which the test specimen lost five percent of its initial
weight.
TABLE-US-00001 Formulations Hand Cast Nova 1994 PS resin 40 g
Methylene chloride 178 g Flame Retardant 0.2 g-10 g Pentane 4 g
Experimental
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene
Step 1: General Procedure for Aromatic Bromination of
Diphenylethane (DPE):
[0044] A 500 mL round-bottom, 4-neck flask equipped masterflex
pump, mechanical stirrer, thermocouple, siltherm condenser, and HBr
scrubber was charged with DPE (50 g, 0.274 mol), 100 mL of
halocarbon solvent (dibromomethane (DBM), dichloroethane (EDC), or
bromochloromethane (BCM)). The mixture was stirred to dissolve the
DPE and FeBr.sub.3 or Fe (0.0075 mole) was added. Bromine (5.5
equivalents) was added dropwise over two hours. The temperature of
the reaction increased via exotherm from 22.degree. C. to
35.degree. C. HBr evolution was measured to gage the reaction.
After the reaction, additional solvent was added to the reaction
(enough to make up a 1 gram/3 mL product/solvent ratio) and 100 mL
of deionized (DI) water or 5% HBr was added. The reaction was
stirred until it turned light orange. The layers were then phase
separated. Approximately 10% (by weight) of the product was removed
and dried under vacuum using a rotary evaporator (rotovap). The
dried sample was analyzed for total organic bromide and iron
content.
TABLE-US-00002 Theoretical Formula Weight 616.3 g/mol Molecular
Formula C.sub.14H.sub.8.5Br.sub.5.5 Organic Bromide 71.3 Fe (by
ICP) <20 ppm
1,1 '-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene
Step 2: Photolytic Procedure for Aliphatic Bromination of
BromoDPE:
[0045] A 1 L round-bottom, 4-neck flask equipped with a 250 mL
addition funnel, mechanical stirrer, thermocouple, siltherm
condenser, and HBr scrubber was charged with multibrominated DPE
(152.2g; 0.245 mol) and 456 mL of halocarbon solvent (DBM, EDC, or
BCM). The reaction mixture was heated to reflux. Either a GE 250
watt reflector lamp or Hanovia UV blacklights were used to catalyze
the aliphatic bromination. Bromine (2 molar equivalents) was added
dropwise over two hours. If solids were present at the beginning of
the reaction, they dissolved after about 10% of the bromine was
added. If using EDC or BCM, some solids may precipitate during the
last 10% of the bromine addition. Stirring of the reaction was
continued for 3-4 hours after the bromine addition and was
monitored by HBr evolution. The reaction mixture was either
rotovapped or solvent evaporated and filtered to isolate the
product. Yield of the reaction was 50-95% depending on the method
of isolation.
1,1'-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene
Step 2: AIBN Procedure for Aliphatic Bromination of BromoDPE:
[0046] A 1 L round-bottom, 4-neck flask equipped with a mechanical
stirrer, thermocouple, and a siltherm condenser was charged with
multibrominated DPE (50 g; 0.81 mole) and 40 mL of halocarbon
solvent (DBM, EDC, or BCM), bromine (28.5 g; 0.18 mol), and 40 mL
of DI water. The reaction mixture was heated to 70.degree. C. A
slurry of 1.1 g AIBN and 5 mL of water was added over three hours.
The reaction was stirred at 70.degree. C. for two additional hours
after the last AIBN charge. The reaction mixture was then cooled
and the aqueous layer was phase separated. The reaction mixture was
washed with DI water and NaHSO.sub.3 to remove any residual
bromine, then DI water. The solvent was removed by rotovap or
filtered to isolate the product. Yield of the reaction ranged from
62-95%.
The target analysis of the final product is:
TABLE-US-00003 Theoretical Formula Weight 774.1 g/mol Molecular
Formula C.sub.14H.sub.6.5Br.sub.7.5 Organic Bromide 76.7
Hydrolizable Bromide >15% Target Aromatic Bromine 5.5-6 Target
Aliphatic Bromine 1.5-2.0 Average Aromatic Bromine 6.0 Average
Aliphatic Bromine 1.6 Inorganic Bromide <1% TGA (5% weight loss)
>210.degree. C. Isothermal TGA (200.degree. C./30 min) ~88%
[0047] In view of the many changes and modifications that can be
made without departing from principles underlying the invention,
reference should be made to the appended claims for an
understanding of the scope of the protection to be afforded the
invention.
* * * * *