U.S. patent application number 10/251547 was filed with the patent office on 2003-02-13 for flame retardants and flame retardant compositions formed therewith.
Invention is credited to Landry, Susan D..
Application Number | 20030030043 10/251547 |
Document ID | / |
Family ID | 25335553 |
Filed Date | 2003-02-13 |
United States Patent
Application |
20030030043 |
Kind Code |
A1 |
Landry, Susan D. |
February 13, 2003 |
Flame retardants and flame retardant compositions formed
therewith
Abstract
The flame retardant additive compositions comprise (a) one or
more bromocycloaliphatic flame retardants; (b) one or more
bromoaromatic flame retardants; and (c) one or more synthetic
zeolites. Flame retardant polymer compositions comprising at least
one thermoplastic polymer such as HIPS with which has been blended,
singly and/or in one or more combinations, a flame retardant amount
of at least (a), (b), and (c) have a very desirable balance of
properties.
Inventors: |
Landry, Susan D.; (Baton
Rouge, LA) |
Correspondence
Address: |
Mr. Philip M. Pippenger
Patent & Trademark Division
Albemarle Corporation
451 Florida Street
Baton Rouge
LA
70801-1765
US
|
Family ID: |
25335553 |
Appl. No.: |
10/251547 |
Filed: |
September 19, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10251547 |
Sep 19, 2002 |
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09861348 |
May 18, 2001 |
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6489390 |
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Current U.S.
Class: |
252/609 |
Current CPC
Class: |
C08K 3/34 20130101; C08K
5/02 20130101; C08K 5/03 20130101 |
Class at
Publication: |
252/609 |
International
Class: |
C09K 021/00 |
Claims
That which is claimed is:
1. A flame retardant additive composition which comprises (a) one
or more bromocycloaliphatic flame retardants, (b) one or more
bromoaromatic flame retardants, and (c) one or more synthetic
zeolites; in proportions in the range of about 15 to about 50 wt %
of(a), in the range of about 35 to about 70 wt % of (b), and in the
range of about 5 to about 25 wt % of (c), with the total of (a),
(b), and (c) being 100 wt %.
2. A composition of claim 1 wherein said proportions are in the
range of about 20 to about 40 wt % of (a), in the range of about 45
to about 65 wt % of (b), and in the range of about 7 to about 20 wt
%, of (c), with the total of (a), (b), and (c) being 100 wt %.
3. A composition of claim 1 wherein said proportions are in the
range of about 30 to about 40 wt % of (a), in the range of about 50
to about 55 wt % of (b), and in the range of about 8 to about 15 wt
%, of (c), with the total of (a), (b), and (c) being 100 wt %.
4. A composition of any of claims 1, 2, or 3 wherein (b) consists
essentially of a bromoaromatic compound containing at least two
polybromoaromatic groups in the molecule.
5. A composition of claim 4 wherein (a) consists essentially of
1,2,5,6,9,10-hexabromocyclododecane.
6. A composition of claim 4 wherein (a) is
1,2,5,6,9,10-hexabromocyclodode- cane, (b) is
1,2-bis(pentabromophenyl)ethane, and (c) is zeolite-A.
7. A composition of any of claims 1, 2, or 3 further comprising at
least one flame retardant synergist and at least one tin-containing
thermal stabilizer.
8. A composition of claim 7 wherein (a) is
1,2,5,6,9,10-hexabromo-cyclodod- ecane, (b) is
1,2-bis(pentabromophenyl)ethane, and (c) is zeolite-A.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This is a division of prior commonly-owned co-pending
application Ser. No. 09/861,348, filed May 18, 2001, incorporated
herein by reference.
TECHNICAL FIELD
[0002] This invention relates to additive compositions that serve
as flame retardants and that have the capability, when blended with
suitable thermoplastic polymers, of providing thermoplastic polymer
compositions having a balance of excellent properties in addition
to flame resistance. This invention also relates to the resultant
flame retarded polymer compositions.
BACKGROUND
[0003] Over the years much effort has been devoted to the discovery
and development of effective flame retardants for use in
thermoplastic polymers. While in many cases effective flame
retardancy can be achieved, one or more other properties of the
resultant polymer compositions in which the flame retardant is used
are often sacrificed. For example, significant loss may occur in
the thermal stability, the impact, tensile, or flexural strength
properties, the melt flow characteristics, or the recyclability of
polymer processing residues.
[0004] Thus a welcome contribution to the art of would be the
provision of new additive compositions having the capability, when
blended with suitable thermoplastic polymers, of providing
thermoplastic polymer compositions having a balance of excellent
properties in addition to flame resistance. This invention is
deemed to constitute such a contribution.
BRIEF SUMMARY OF THE INVENTION
[0005] Provided by this invention is a flame retardant additive
composition which comprises: (a) at least one bromocycloaliphatic
flame retardant; (b) at least one bromoaromatic flame retardant;
and (c) at least one synthetic zeolite. Also provided by this
invention is a flame retardant polymer composition comprising at
least one thermoplastic polymer which contains at least polymerized
ethylenic linkages therein, with which polymer has been blended at
least (a) one or more bromocycloaliphatic flame retardants; (b) one
or more bromoaromatic flame retardants; and (c) one or more
synthetic zeolites, (a), (b), and (c) being blended with said
thermoplastic polymer individually or in any combination of at
least any two or at least any three of (a), (b) and (c).
[0006] Other embodiments and features of this invention will be
still further apparent from the ensuing description, accompanying
drawings, and appended claims.
FURTHER DETAILED DESCRIPTION OF THE INVENTION
[0007] Preferred bromocycloaliphatic flame retardant compounds for
use in this invention have a plurality of bromine atoms directly
bonded to a cycloaliphatic ring. Non-limiting examples of such
flame retardants include pentabromocyclohexane,
pentabromochlorocyclohexane, hexabromocyclohexane,
1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane,
tetrabromo-cyclooctane, hexabromocyclooctane,
hexabromocyclododecane, and analogous bromine-containing
cycloaliphatic compounds having at least two, and preferably at
least four, bromine atoms directly bonded to a cycloaliphatic ring
system. Optionally, the bromocycloaliphatic flame retardant
compound also has one or more chlorine atoms in the molecule. The
cycloaliphatic ring can have one or more alkyl side chains which
can, but need not, be substituted by one or more bromine or
chlorine atoms. Mixtures of two or more such compounds can be used,
and the components of such mixtures can be in any proportions
relative to each other. Most preferred in the practice of this
invention is 1,2,5,6,9,10-hexabromocycl- ododecane, which is a
commercially-available flame retardant.
[0008] The one or more bromoaromatic flame retardants used in the
practice of this invention can contain a single aromatic ring or
two or more aromatic rings in the molecule, and preferably have a
plurality of bromine atoms directly bonded to at least one aromatic
ring. These compounds may also contain one or more chlorine atoms
in the molecule, although it is preferred that all of the halogen
atoms in the compound be bromine atoms. The aromatic ring(s) may in
turn have one or more alkyl substituents which may themselves be
substituted by one or more bromine or chlorine atoms. Among
suitable bromoaromatic flame retardants having a single aromatic
ring in the molecule are such non-limiting examples as
1,3,5-tribromobenzene, 1,2,4-tribromobenzene,
1,2,4,5-tetrabromobenzene, 2,3,5,6-tetrabromo-p-xylene,
pentabromobenzene, pentabromochlorobenzene, hexabromobenzene, and
similar bromoaromatic hydrocarbons having at least 3 and preferably
at least 4 bromine atoms in the molecule, at least two of which are
bonded to the aromatic ring itself These mononuclear
polybromoaromatics preferably contain carbon, bromine, and
optionally hydrogen and/or chlorine atoms in the molecule.
[0009] More preferred bromoaromatic compounds contain at least two
polybromoaromatic groups in the molecule which maybe fused ring
compounds or compounds in which the aromatic groups are bonded
together through (i) a carbon-to-carbon bond from one aromatic ring
to another, (ii) a divalent oxygen atom (--O--), (iii) an alkylene
group having in the range of 1 to 3 carbon atoms, e.g., methylene
(--CH.sub.2--), ethylene (--CH.sub.2CH.sub.2--), ethylidene,
2,2-propylidene, etc., or (iv) bisimide functionality. Thus these
compounds typically contain carbon, bromine, and optionally
hydrogen, ether oxygen, thioether sulfur, imido nitrogen atoms
bonded to carbonyl groups, and/or chlorine atoms in the molecule.
Non-limiting examples of such flame retardants include
perbromobiphenyl, perbromonaphthalene, bis(tetrabromophenyl) ether,
bis(pentabromophenyl) ether, bis(pentabromophenyl)thioether,
bis(pentabromophenyl)methane, 1,1-bis(pentabromophenyl)ethane,
1,2-bis(pentabromo-phenyl)ethane,
1,3-bis(pentabromophenyl)-propane, tetradecabromodiphenoxybenzene,
ethylenebistetrabromophthalimide, and analogous compounds.
Bis(pentabromophenyl)ether and 1,2-bis(pentabromophenyl)ethane are
preferred bromoaromatic compounds for use in this invention.
[0010] Various synthetic zeolites can be used including the
following: Zeolites A, X, M, F, B, H, J, W, Y, and L described
respectively in U.S. Pat. Nos. 2,822,243; 2,822,244; 2,995,423,
2,996,358; 3,008,803; 3,010,789; 3,011,869; 3,102,853; 3,130,007;
and 3,216,789, respectively. Still other synthetic zeolites are
known, such as ZSM-5, and these can be used. In all cases, the
zeolite should be used in the form of a fine dry powder, free of
lumps or clumps. From the cost-effectiveness standpoint zeolite-A
is a preferred material. In a preferred embodiment, the selected
zeolite is calcined before use in order to reduce its water content
without materially disrupting its physical structure or average
pore size. For example, zeolite-A typically contains about 18.5%
water, and calcining can prove useful in reducing this water
content, thereby increasing its usefulness in the compositions of
this invention. Other zeolites such as zeolite-X which typically
contains about 24% water, and zeolite-Y which has a typical water
content of about 25% may also be improved for use in this invention
by calcining them prior to use to reduce their water contents but
without destroying their structure. An advantage of zeolite ZSM-5
is its normal low content of water, about 5%.
[0011] The relative proportions among (a) at least one
bromocycloaliphatic flame retardant; (b) at least one bromoaromatic
flame retardant; and (c) at least one synthetic zeolite can be
varied. However typically in the range of about 15 to about 50 wt
%, and preferably in the range of about 20 to about 40 wt %, of
this mixture is one or more components of (a), typically in the
range of about 35 to about 70 wt %, and preferably in the range of
about 45 to about 65 wt %, of this mixture is one or more
components of (b), and typically in the range of about 5 to about
25 wt %, and preferably in the range of about 7 to about 20 wt %,
of this mixture is one or more components of (c), with the total of
(a), (b), and (c) being 100 wt %. Particularly preferred relative
proportions are about 30-40 wt % of (a), about 50-55 wt % of (b),
and about 8-15 wt % of (c), again with the total of (a), (b), and
(c) being 100 wt %. It will be understood that the foregoing 100 wt
% values just referred to relate to the combination of (a), (b),
and (c)--other flame retardants which do not detract materially
from the effectiveness of the combination of (a), (b), and (c) can
also be present independently of this 100% value. In other words,
the total of 100% is away of expressing the relative proportions of
components (a), (b), and (c) only. Other flame retardant
components, if used, are not to be included within this total of
100%.
[0012] The thermoplastic polymer compositions to which this
invention is especially adapted are thermoplastic polymers having
polymerized ethylenic linkages. By this is meant that the structure
of the polymer includes polymer units formed from one or more
monomers having a polymerizable terminal CH.sub.2.dbd.CR-- group
which enters into the formation of the polymer. Such polymers are
typified by (i) polyolefin polymers, (ii) vinylaromatic polymers,
(iii) functionally-substituted alpha-olefin polymers, and (iv)
elastomers derived at least in part from diene monomers
copolymerized with one or more monomers of (i), (ii), and/or (iii).
Polyolefin polymers are formed by homopolymerization or
copolymerization of alpha-olefin monomers having in the range of 2
to about 8 carbon atoms, non-limiting examples of which are
polyethylene, polypropylene, polybutene, polyisobutylene, and
copolymers such as ethylene-propylene copolymers, and ethylene
copolymerized with one or more such monomers as 1-pentene,
3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene,
1-octene, or analogs thereof. The vinylaromatic polymers (also
sometimes referred to as styrenic polymers) are homopolymers or
copolymers formed from vinylaromatic monomers having 8 to about 16
carbon atoms per molecule, such as styrene, 2-methylstyrene,
3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene,
alpha-methylstyrene, 4-tert-butylstyrene, 3,5-diethylstyrene,
2,4,5-trimethylstyrene, vinylnaphthalene, or analogs thereof
Functionally-substituted alpha-olefin polymers which may be used in
the practice of this invention are copolymers of at least one
1-olefin and/or styrenic monomer and at least one copolymerizable
carboxylic acid, carboxylic acid ester and/or nitrile, non-limiting
examples of which include ethylene-acrylic acid copolymer,
ethylene-vinylacetate copolymer, ethylene-acrylonitrile copolymer,
ABS, MABS, SAN, and similar materials. Elastomers derived at least
in part from polymerized diene monomers which may be used in the
practice of this invention include elastomeric terpolymers of
ethylene, propylene, and at least one diene such as norbornadiene
or hexadiene, butadiene-styrene elastomers, butadiene-acrylonitrile
elastomers, and similar materials.
[0013] It is contemplated that it maybe possible to form flame
retardant compositions of this invention using polymer blends
containing substantial proportions of one or more styrenic polymers
such as polyphenylene ether/polystyrene, polyphenylene ether/HIPS,
or aromatic polycarbonate/ABS blends.
[0014] Preferred substrate or host polymers are the polyolefin
homopolymers and copolymers, especially those based in whole or in
part on ethylene or propylene. More preferred are the vinylaromatic
polymers. These can be homopolymers, copolymers or block polymers
and such polymers can be formed from such vinylaromatic monomers as
styrene, ring-substituted styrenes in which the substituents are
one or more C.sub.1-6 alkyl groups and/or one or more halogen
atoms, such as chlorine or bromine atoms, alpha-methylstyrene,
ring-substituted alpha-methylstyrenes in which the substituents are
one or more C.sub.1-6 alkyl groups and/or one or more halogen
atoms, such as chlorine or bromine atoms, vinylnaphthalene, and
similar polymerizable styrenic monomers--i.e., styrenic compounds
capable of being polymerized by means of peroxide or like catalysts
into thermoplastic resins. Homopolymers and copolymers of simple
styrenic monomers (e.g., styrene, p-methylstyrene,
2,4-dimethylstyrene, alpha-methyl-styrene, p-chloro-styrene, etc.)
are preferred from the standpoints of cost and availability.
[0015] Impact-modified polystyrenes (IPS) that are preferably used
may be medium-impact polystyrene (MIPS), high-impact polystyrene
(HIPS), or blends of HIPS and GPPS (sometimes referred to as
crystal polystyrene). These are all conventional materials. The
rubber used in effecting impact modification is most often, but
need not be, a butadiene rubber. High-impact polystyrene or blends
containing a major amount (greater than 50 wt %) of high-impact
polystyrene together with a minor amount (less than 50 wt %) of
crystal polystyrene are among preferred substrate or host polymers.
Particularly preferred thermoplastic polymers in which the flame
retardant additive compositions of this invention are used are the
high-impact polystyrene polymers (HIPS), whether or not they
contain crystal polystyrene.
[0016] The quantity of the (a), (b) and (c) additive components in
the thermoplastic polymer composition having polymerized ethylenic
linkages will vary somewhat depending on such factors as the
identity and relative proportions of the particular components of
(a), (b) and (c) used, the identity of the thermoplastic polymer in
which these components are being used, the amount and type of flame
retardant synergist, if any, being used, and the amount of flame
retardancy desired in the finished blend. In all cases however the
quantity used must be a flame retardant amount, i.e., an amount
that increases the flame retardancy in the particular thermoplastic
polymer composition being flame retarded. In preferred embodiments
a flame retardant amount is an amount which provides test specimens
giving at least a V-2 rating in the standard UL test procedure as
described in UL-94 Standard for Tests for Flammability of Plastic
Materials for Parts in Devices and Appliances. Without limiting the
scope of this invention, the amount of the flame retardant
compositions of this invention proportioned as above in the
substrate or host polymer will usually be such as to provide a
bromine content (as Br) in the range of about 2 to about 8 wt %,
more usually a bromine content of about 3 to about 6 wt %, such as
about 4 wt % especially in the case of some types of HIPS.
[0017] The additive and polymer compositions of this invention can
contain additional components. One preferred additional component
is one or more flame retardant synergists such as, for example,
antimony trioxide, antimony pentoxide, antimony phosphate,
KSb(OH).sub.6, NH.sub.4SbF.sub.3, sodium antimonate, potassium
antimonate, zinc antimonate, nickel antimonate, KSb tartrate, zinc
borate, or a mixed oxide of boron and zinc which can contain water
of hydration, or which can be anhydrous, such as dodecaboron
tetrazinc docosaoxide heptahydrate (4ZnO.6B.sub.2O.sub.3.7H.s-
ub.2O); zinc boratemonohydrate (4ZnO.B.sub.2O.sub.3.H.sub.2O); and
anhydrous zinc borate (2ZnO.3B.sub.2O.sub.3). Amounts of
synergist(s) in the range of about 10 to about 40 wt % based on the
total weight of (a), (b), and (c) will usually suffice. Preferred
amounts are in the range of about 20 to about 40 wt % based on the
total weight of (a), (b), and (c).
[0018] Another preferred type of additive is at least one tin-based
thermal stabilizer, such as an alkyltin mercaptoalkanoate. It is
believed on the basis of available information that such compounds
have two alkyl groups and at least one mercaptoalkanoate group
bonded to an atom of tin. According to this hypothesis, the
compounds may exist either as a cyclic compound, as a non-cyclic
compound, or as a mixture of such compounds. The preferred alkyltin
mercaptoalkanoates are those which are solids at room temperature
as they have no adverse plasticizing effect upon the styrenic
polymer compositions of this invention. However, for some
applications liquid alkyltin mercaptoalkanoates can be used.
Preferred solid materials that are available from commercial
sources include, for example, Brostab M36, which is described by
its manufacturer as a butyltin mercaptopropionate, Brostab OM36,
which is described by the manufacturer as an octyltin
mercaptopropionate, and equivalent materials. Products like Brostab
M36 have also been variously described by one manufacturer as a
butyltin mercaptide, butyltin (3-mercaptopropionate), and
dibutyltin (3-mercaptopropionate). It is indicated by that
manufacturer to contain approximately 35% wt % of tin, and it melts
at about 120-123.degree. C. The manufacturer has also referred to
Brostab OM36 as an octyltin mercaptide, a dioctyltin thioester, and
as octyltin mercaptopropionate, and has indicated that it contains
approximately 26.5 wt % of tin. It is reasonable to expect that
compounds of this type with other alkyl groups (e.g., C.sub.5-7,
and C.sub.9 and above) can be produced that exist as solids at room
temperature. Compounds which are understood to be equivalent or
suitably similar to Brostab M36 from Brlocher GmbH, are Tinstab BTS
261 from Akcros Chemicals, Thermolite 35 from Elf Atochem S. A.,
and Prosper M36 or Okstan M36, from Comtin. The thermal
decomposition temperature of Tinstab BTS 261 is reported to be
317.degree. C. Amounts of such tin-based thermal stabilizers are
typically in the range of about 4 to about 9 wt % based on the
total weight of (a), (b), and (c). Preferred amounts are in the
range of about 5 to about 8 wt % based on the total weight of (a),
(b), and (c).
[0019] Other additives which may be used if desired include, for
example, antioxidants, metal scavengers or deactivators, pigments,
fillers, impact modifiers, dyes, anti-static agents, processing
aids, mold release agents, lubricants, anti-blocking agents, other
flame retardants, other thermal stabilizers, and similar materials.
Such components are usually used in conventional quantities in
accordance with customary practice in the industry, or such as may
be recommended by the additive manufacturer. Conduct of a few
preliminary optimization tests using different proportions of the
selected components can also prove useful. Any additive which would
materially detract from one or more of the advantageous performance
properties of the composition of this invention when devoid of such
additive, should not be included in the composition.
[0020] When preparing flame-retarded polymer compositions of this
invention, the individual components of the flame retardant
composition of this invention can be blended separately and/or in
subcombinations with the substrate or host polymer in appropriate
proportions. However, it is definitely preferable to blend a
preformed additive composition of this invention with the polymer
as this minimizes the possibility of blending errors, and is a
simpler and less time-consuming blending operation.
[0021] The additive compositions of this invention can be
formulated as powder blends of the additive components using
conventional blending apparatus and techniques. Granular blends can
be produced using conventional compactors. Alternatively, the
components can be melt blended together, with the inclusion, where
necessary or appropriate, of some of the substrate polymer in which
the additive composition is to blended. Preferred additive
compositions of this invention are composed of compacted granules
of at least above components (a), (b) and (c), such as for example,
granules composed of about 30-40 wt % of
1,2,5,6,9,10-hexabromocyclododecane, about 50-55 wt % of
bis(pentabromophenyl)ether or 1,2-bis(pentabromophenyl)ethane, and
about 8-15 wt % of a synthetic zeolite such as zeolite A, the total
of (a), (b), and (c) being 100 wt %. These compositions can also
contain one of more flame retardant synergists and one or more
tin-based stabilizers proportioned as indicated above, as well as
one or more other additives that are useful for improving the
properties or processing characteristics of polymers.
[0022] Various known procedures can be used to prepare the
flame-retardant polymer blends or formulations of this invention.
For example the substrate or host polymer and an additive
composition of this invention(i.e., a preformed additive
composition comprising at least components (a), (b), and (c))
together with whatever suitable auxiliary additive components as
maybe selected can be mixed in suitable proportions in a powder
blender and then melt extruded. Although less preferable, the
substrate or host polymer and the individual components (a), (b),
and (c) and whatever suitable auxiliary additive components as may
be selected can be added separately and/or in subcombinations
(i.e., other than in a combination of(a), (b), and (c) of this
invention) to the blending apparatus and mixed during and/or
subsequent to the additions. Alternatively the materials,
preferably comprising a preformed additive composition of this
invention comprising at least components (a), (b), and (c) rather
than the individual components, can be compounded using an
extruder, most preferably a twin-screw extruder. However, other
apparatus such as a Buss kneader may be found useful for such
compounding. If glass fibers are being used as a component, it is
desirable to add the glass fibers at a downstream portion of the
extruder in order to avoid excessive glass fiber breakage. The
other additive components utilized in the practice of this
invention can be added with the polymer in the initial feed port of
the extruder or they can be added to the extruder further
downstream. The extrudate from the extruder is typically converted
into granules or pellets either by cooling strands of the extruding
polymer and subdividing the solidified strands into granules or
pellets, or by subjecting the extrudate to concurrent die-faced
pelletizing and water-cooling or air-cooling.
[0023] The compounded polymers of this invention can be processed
in conventional ways. For example, the compounds can be transformed
into the final articles by appropriate processing techniques such
as injection molding, compression molding, extrusion, or like
procedures.
[0024] The practice and advantages of this invention are
illustrated by the following non-limiting Examples.
EXAMPLE 1
[0025] A flame retardant composition of this invention is formed by
blending together 1,2,5,6,9,10-hexabromocyclododecane,
decabromodiphenyl-1,2-ethane, and zeolite-A in proportions of
35:53:12 parts by weight, respectively.
EXAMPLE 2
[0026] A flame retardant composition of this invention is formed by
blending together 1,2,5,6,9,10-hexabromocyclododecane,
decabromodiphenyl-1,1-ethane, and zeolite-A in proportions of
35:53:12 parts by weight, respectively.
EXAMPLE 3
[0027] A flame retardant composition of this invention is formed by
blending together 1,2,5,6,9,10-hexabromocyclododecane,
decabromodiphenyl-1,2-ethane, and zeolite-A in proportions of
38:52:10 parts by weight, respectively.
EXAMPLE 4
[0028] A flame retardant composition of this invention is formed by
blending together 1,2,5,6,9,10-hexabromocyclododecane,
decabromodiphenyl-1,1-ethane, and zeolite-A in proportions of
32:57:11 parts by weight, respectively.
EXAMPLE 5
[0029] A flame retardant composition of this invention is formed by
blending together 1,2,5,6,9,10-hexabromocyclododecane,
decabromodiphenyloxide, and zeolite-A in proportions of 35:53:12
parts by weight, respectively.
EXAMPLE 6
[0030] With individual samples of each of the five compositions of
Examples 1-5 is blended antimony trioxide in proportions of 1 part
by weight antimony trioxide per each 5 parts by weight of the
respective compositions of Examples 1-5, to thereby form five
Sb.sub.2O.sub.3-containing compositions of this invention.
EXAMPLE 7
[0031] With individual samples of each of the five compositions of
Examples 1-5 is blended anhydrous sodium borate in proportions of 1
part by weight of the sodium borate per each 5 parts by weight of
the respective compositions of Examples 1-5, to thereby form five
2ZnO.3B.sub.2O.sub.3-containing compositions of this invention.
EXAMPLE 8
[0032] With individual samples of each of the five compositions of
Examples 1-5 are blended antimony trioxide and butyltin
mercaptopropionate solids (e.g., Brostab OM36), in proportions of 1
part by weight of the antimony oxide and 0.35 part by weight of the
butyltin mercaptopropionate solids per each 5 parts by weight of
the respective compositions of Examples 1-5, to thereby form five
compositions of this invention containing a flame retardant
synergist and a tin-containing thermal stabilizer.
EXAMPLE 9
[0033] Eight flame retardant polymer compositions of this invention
are formed having the following respective compositions:
[0034] 1) HIPS with which is blended 5 wt % of the composition of
Example 1.
[0035] 2) HIPS with which is blended 5 wt % of the composition of
Example 2.
[0036] 3) HIPS with which is blended 5 wt % of the composition of
Example 3.
[0037] 4) HIPS with which is blended 5 wt % of the composition of
Example 4.
[0038] 5) HIPS with which is blended 5 wt % of the composition of
Example 5.
[0039] 6) HIPS with which is blended 6 wt % of the composition of
Example 6.
[0040] 7) HIPS with which is blended 6 wt % of the composition of
Example 7.
[0041] 8) HIPS with which is blended 6.35 wt % of the composition
of Example 8.
EXAMPLE 10
[0042] The practice and advantages of this invention were
demonstrated in a series of tests in which a high-impact
polystyrene composition of this invention was prepared and
subjected to a number of evaluations. This composition was composed
of 93.65 wt % of high-impact polystyrene, 5 wt % of a mixture
prepared as in Example 1,1 wt % of antimony trioxide, 0.1 wt % of
Barostab M36 (Brlocher GmbH),0.1 wt % Thermolite 42 (Elf Atochem S.
A.), and 0.15 wt % Mark 645, a dibutyltin maleate (Witco
Corporation). Table 1 summarizes the results of a group of tests to
which extruded and injection molded test specimens of this polymer
composition (Polymer A) were subjected. Also shown in Table 1 are
results of parallel control tests conducted with extruded and
injection molded test specimens made from additive-free portions of
the same high-impact polystyrene (Polymer B).
1TABLE 1 Property Polymer A Polymer B UL-94 Rating, 1/8-inch V-2
Burn UL-94 Rating, 1/16-inch V-2 Burn Melt Flow Index, g/10 min
(200.degree. C./5 kg) 4.6 3.8 IZOD Impact Strength, ft-lb/in 2.2
2.4 DTUL, .degree. C. 74 76 Gloss (60.degree. Angle) 51 53
[0043] In melt stability determinations by capillary rheometry at
250.degree. C. and a shear rate of 500/second, the viscosity of
Polymer A remained at about 115 Pa-s for about 20 minutes and then
slowly dropped to about 105 Pa-s afterabout 33 minutes. Polymer B
remained at about 180 Pa-s during the same period of time.
Isothermal TGA melt stability determinations at 250.degree. C.
under nitrogen showed a 1.6 wt % weight loss for Polymer A after 1
hour. Under the same conditions Polymer B showed a 0.9 wt % weight
loss in one hour. Thus Polymer A showed good thermal stability over
extended periods.
[0044] In another series of evaluations, the high-impact
polystyrene composition of this invention (Polymer C) was composed
of 92.95 wt % of high-impact polystyrene, 5.7 wt % of a mixture
prepared as in Example 1, 1 wt % of antimony trioxide, 0.1 wt %
Barostab M36 (Barlocher GmbH), 0.1 Thermolite 42 (Elf Atochem), and
0.15 wt % Mark 645 (Witco). Table 2 summarizes the results of a
group of tests to which extruded and injection molded test
specimens of this polymer composition (Polymer C) were subjected.
Also shown in Table 2 are results of parallel control tests
conducted with extruded and injection molded test speci-mens made
from additive-free portions of the same high-impact polystyrene
(Polymer D).
2TABLE 2 Property Polymer C Polymer D UL-94 Rating, 1/8-inch V-2
Burn UL-94 Rating, 1/16-inch V-2 Burn Melt Flow Index, g/10 min
(200.degree. C./5 kg) 4.5 3.8 IZOD Impact Strength, ft-lb/in 2.3
2.8 DTUL, .degree. C. 73 74 Vicat Softening Temperature, .degree.
C. (1 kg) 101 103 Tensile Strength, psi .times. 10.sup.3 3.6 3.6
Tensile Modulus, psi .times. 10.sup.5 3.1 3.1 Elongation at Break,
% 36 30 Flexural Strength, psi .times. 10.sup.3 7.3 7.0 Flexural
Modulus, psi .times. 10.sup.5 3.1 3.0
[0045] In melt stability determinations by capillary rheometry at
250.degree. C. and a shear rate of 500/second, the viscosity of
Polymer C remained at about 149 Pa-s for about 25 minutes and then
slowly dropped to about 1135 Pa-s after about 33 minutes. Polymer D
remained at about 170 Pa-s during the same period of time.
Isothermal TGA melt-stability determinations at 250.degree. C.
under nitrogen showed an weight loss of about 2.7 wt % for Polymer
C after 1 hour. Under the same conditions Polymer D showed a 1 wt %
weight loss in one hour.
[0046] In injection molding trials conducted at increasing
temperatures it was found that at 247.degree. C. no signs of
discoloration occurred in Polymer C.
[0047] Recyclability tests were conducted in order to assess the
extent of change in properties of Polymers C and D during repeated
injection molding cycles. Thus after each of four consecutive
injection molding cycles the test pieces were ground to a small
particle size and then the particles were injection molded again,
thus giving 5 repetitions of injection molding on the same
polymeric materials. After the first, third and fifth injection
moldings, the properties of test specimens from those runs were
determined. It was observed that very little change in tensile,
flexural, UL-94 LOI, DTUL, or Vicat softening properties occurred
in either Polymer C or D after these multiple recycles. Table 3
shows the results of the recyclability tests on Polymers C and D in
which property changes were observed.
3TABLE 3 Polymer Polymer Property C D Melt Flow Index, g/10 min
(200.degree. C./5 kg), after 1 pass 4.5 3.8 Melt Flow Index, g/10
min (200.degree. C./5 kg), after 4.8 4.1 3 passes Melt Flow Index,
g/10 min (200.degree. C./5 kg), after 5.1 4.1 5 passes IZOD Impact
Strength, ft-lb/in, after 1 pass 2.3 2.8 IZOD Impact Strength,
ft-lb/in, after 3 passes 2.2 2.8 IZOD Impact Strength, ft-lb/in,
after 5 passes 2.0 2.6 Color Change after 3 passes, .DELTA.E
(relative to color after 1.9 2.4 1st pass) Color Change after 5
passes, .DELTA.E (relative to color after 2.9 4.0 1st pass)
[0048] From the foregoing tests with Polymers C and D it was
concluded that the composition of Polymer C achieved V-2 ratings at
1/8-inch and {fraction (1/16)}-inch at low loadings, that impact
strength and DTUL were very similar to the neat HIPS resin (Polymer
D), that the additive combination of this invention increased melt
flow, that melt stability by capillary rheometry and isothermal TGA
was good over extended periods, and that the composition of this
invention has extremely good recyclability characteristics since
very little change in flammability, physical properties, and color
were observed after five injection molding cycles.
* * * * *