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
2000-08-18
2003-02-11
Szekely, Peter (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...
C524S147000, C524S153000, C524S281000, C524S303000, C524S304000, C524S371000, C524S373000, C524S397000, C524S399000, C524S400000, C524S405000, C524S410000, C524S411000, C524S412000, C524S414000, C524S436000, C524S151000, C524S152000
Reexamination Certificate
active
06518344
ABSTRACT:
FILED OF INVENTION
The present invention concerns a polyolefin composition. More particularly, the present invention concerns a flame retarded polyolefin composition that retains good physical properties after long-term heat aging and enhanced as-molded flammability properties.
BACKGROUND OF THE INVENTION
The use of flame retardant additives in polymer resin systems is well-known in the prior art. A number of different flame retardant additive systems are commercially available for incorporation into polymer resin systems or blends. Such additives serve to impart flame retardant/resistant properties to the polymers they are added to, reducing the ease of ignition and decreasing the time for the polymer to extinguish after application and removal of an ignition source.
The use of flame retardant additives in polyolefin systems, such as polypropylene containing and/or based polymer systems, is also well-known in the prior art. Flame retarded polypropylenes are used in a wide variety of applications where flame retarded properties are required. Examples of such applications include, for example, electronic components and parts, household fixtures and accessories such as furniture and fabric, automotive and appliance parts such as control panels, clothes baskets, drums, dashboards, seat covers, and carpeting.
Unfortunately, the use of flame retardant additives in polyolefin compositions, such as polypropylene, can result in a meaningful loss in the physical properties of the composition. The flame retardant additive can detrimentally affect the retention of physical properties of the polyolefin composition, particularly after long-term heat aging. In many applications, this detrimental affect on the retention of physical properties is undesirable and/or unacceptable.
SUMMARY OF INVENTION
The present invention provides a new and improved flame retarded polyolefin composition that exhibits excellent retention of physical properties after long-term heat aging. The composition according to the invention exhibits excellent moldability and may be easily colored. Moreover, the composition exhibits little or no undesirable change in the original as-molded color after long term heat aging or prolonged use at temperatures above normal room temperatures.
In a preferred embodiment the composition comprises: (I) at least one polyolefin; (II) a halogen-containing flame retardant additive; (III) from at least about 1.00% by weight to about 2.5% by weight of a stabilizer package; and (IV) from about 0% to about 1.0% by weight of an acid/halogen scavenger. The stabilizer package (III) comprises by weight from about 20% to about 80% of a hindered phenolic antioxidant (IIIa), from about 20% to about 80% of a phosphite-containing phenolic antioxidant (IIIb), and from about 0% to about 40% of a thio-ester antioxidant (IIIc). In addition to displaying excellent color and physical property retention characteristics upon long-term heat aging, the composition of the present invention displays an improved UL94 burn rating.
The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
As further discussed in greater detail below, the inventive composition of the present invention comprises a blend of: (I) at least one polyolefin, (II) a halogen-containing flame retardant additive; (III) from at least about 1.00% by weight to about 2.5% by weight of a stabilizer package; and (IV) from about 0% to about 1.0% by weight of an acid/halogen scavenger. Each component of the composition is separately discussed below:
(I) Polyolefin
The flame retarded polyolefin composition according to the present invention comprises at least one polyolefin. Preferably, the polyolefin comprises a conventional semicrystalline homopolymer or copolymer of polypropylene, a metallocene polyolefin or mixtures of such homopolymer, copolymer and metallocene materials. The composition comprises in weight percent from about 26.5% to about 95%, preferably from about 75% to about 93%, and more preferably from about 75% to about 90% of such polyolefin materials.
The number average molecular weight of the polypropylene polymers is preferably above about 10,000 and more preferably above about 50,000. Such polypropylene polymers are preferably produced using a Ziegler catalyst. The polypropylene polymers useful in preparing the polymer blends of the present invention are well-known to those skilled in the art and many are commercially available. Examples of such commercially available semicrystalline polypropylenes include Aristech F007S and F007F, Shell 7C06 and 5A97, Exxon PD7/32, Lyondell X0200 and X0201, Aristech 4007F and 4040F and Union Carbide 7C50 (copolymer of propylene and ethylene). Equistar PP8480HU (ethylene-propylene copolymer), Equistar 51S12A (polypropylene homopolymer) and Quantum PP8479HV.
The polyolefin portion of the composition may also include metallocene polyolefins. Specifically, such polyolefins comprise an ethylene copolymer made using a metallocene catalyst or an equivalent single site metal catalyst. Such copolymers include ethylene-butene, propylene, hexene or octene copolymers made using a metallocene or equivalent single site catalyst. Such ethylene copolymers suitable for use in the present invention display a melting point below about 105° C. Such ethylene-butene or hexene copolymers are available commercially from Exxon Chemicals of Houston, Tex., under the trade designation Exact. An example of another commercially available ethylene copolymer suitable for use in the present invention is a saturated ethylene-octene copolymer sold under the trade designation Engage 8100 or POE-8999 by DuPont Dow Elastomers of Wilmington, Del.
The metallocene ethylene copolymer may be present in the polyolefin portion of the composition in an amount from about 0.5%, or about 1% up to about 30%, or to about 20% by weight of the polyolefin portion of the flame retarded polyolefin composition. Also, it will be appreciated that depending upon the particular application, regrind, recycled or other wide specification materials maybe used to form compositions of the present invention.
(II) Flame Retardant Additive
Various halogen-containing flame retardants may be utilized in the composition. Applicants do not view the selection of a particular type of halogen-containing material as being critical to the invention. Examples of suitable halogen-containing flame retardants include brominated dipentaerithritol, tetrabromobisphenol A, ethylenebistetrabromophthalimide, ethylenebisdibromonorbornane-dicarboximide, tetrabromobisphenol A-bis(2,3-dibromopropyl ether), octabromodiphenyl oxide hexabromocyclododecane, hexabromodiphenoxy ethane, decabromodiphenoxy ethane, decabromodiphenyloxide, tris(tribromoneopentyl) phosphate and other halogenated bisphenol derivatives, tetradecabromodiphenoxy benzene, brominated polystyrene, tetradecabromodiphenyloxide, polydibromophenylene oxide, phenoxy terminated bisphenol A carbonate oligomers containing from about 50% to about 60% by weight bromine, brominated epoxy resins containing from about 30% to about 60% by weight bromine, and mixtures thereof.
The halogen-containing flame retardant additive is generally purchased and utilized as a blend in combination with other materials (e.g., a polymer carrier and a synergist). Accordingly, as used in the specification and in the appended claims, the term “halogen-containing flame retardant additive” is intended to reference the halogen-containing flame retardant compound as well as any other materials (e.g., carriers and synergists) that may also be included in the additive as used. For example, Endura 6289 (PP-100) which is available from Polymer Products comprises by weight about 49% to about 54% tetrabrombisphenol A-bis
Chundury Deenadayalu
Mendel Ann
Munro Howard E.
Sanford Roy C.
Ferro Corporation
Rankin, Hill Porter & Clark LLP
Szekely Peter
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