Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-05-18
2002-12-03
Anthony, Joseph D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S469000, C524S492000, C524S464000, C252S609000
Reexamination Certificate
active
06489390
ABSTRACT:
TECHNICAL FIELD
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
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.
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
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).
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
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, tetrabromocyclooctane, 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-hexabromocyclododecane, which is a commercially-available flame retardant.
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-trimbromobenzene, 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.
More preferred bromoaromatic compounds contain at least two polybromoaromatic groups in the molecule which may be 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
2
—), ethylene (—CH
2
CH
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 -bisrpentabromophenyl)ethane, 1,2-bis(pentabromophenyl)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.
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%.
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
Albemarle Corporation
Anthony Joseph D.
Spielman, Jr. Edgar E.
LandOfFree
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