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
2001-04-19
2002-06-11
Wu, David W. (Department: 1713)
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...
C524S425000, C524S447000, C524S449000, C524S445000, C524S495000, C524S497000, C524S492000, C524S494000, C524S413000, C525S240000
Reexamination Certificate
active
06403692
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to filled thermoplastic compositions and fabricated articles thereof.
BACKGROUND OF THE INVENTION
Molded or extruded articles comprising thermoplastic polymers find wide use in a large variety of applications, for example in automobiles, boats, snow mobiles, personal water crafts, all terrain vehicles, home appliances, electronic housings, furniture, floor coverings, wall coverings, footwear such as shoes, boots, ski boots and skates.
Physical property requirements for such articles are varied and application dependent. It is well known to this art that thermoplastic polymers can contain non-polymeric materials as fillers, in order to alter certain of their properties. Thus, various mineral or inorganic fillers can be used in order to change one or more mechanical property of a thermoplastic polymer, such as coefficient of linear thermal expansion; modulus; impact, especially low temperature impact; tensile strength; flexural strength and resilience. For instance, see U.S. Pat. No. 4,528,303 which discloses a polymer matrix comprising a filler prepared by the calcination of clay and, for optimal property performance, the use of a coupling agent.
One important property, especially for the surface of the article, is the resistance to scuffing, sometimes referred to as scratch and mar resistance. “Scuffing” is a surface deformation caused by sliding contacts between two surfaces resulting in a surface or “scuff” mark. For example, when a thermoplastic material used in a vacuum cleaner housing, an automotive bumper fascia, a floor covering or ski boots has a low resistance to scuffing, scuff marks become visible when the vacuum cleaner or bumper occasionally bumps into other objects or when people walk on the floor or when the right ski boot contacts the left ski boot. Such scuff marks are highly undesirable.
SUMMARY OF THE INVENTION
Accordingly, a major object of the present invention is the provision of a filled thermoplastic composition having a balance of mechanical properties, such as processability, stiffness, toughness and scuff resistance, in extruded or molded articles previously unknown to this art.
The filled thermoplastic composition of the present invention comprises (a) a thermoplastic polymer, (b) an uncalcined filler, (c) a calcined filler having an average particle size less than about 2.5 microns and a maximum particle size equal to or less than about 13 microns, optionally (d) an impact modifier and optionally (e) a slip agent.
In another aspect, the present invention involves a method of fabricating (e.g., extruding or molding) articles from a filled thermoplastic composition described hereinabove.
In a further aspect, the invention involves fabricated (e.g., extruded or molded) articles of a filled thermoplastic composition described hereinabove.
The filled thermoplastic compositions of the present invention are especially useful in the preparation of molded objects notably articles having large surfaces prepared by injection molding techniques requiring a good balance of strength and toughness and good scratch and mar resistance. Such properties are particularly desired for fabricated articles in automotive applications such as trims, bumper beams, bumper fascia, pillars, instrument panels and the like; in snow mobile, personal water craft and all terrain vehicle applications such as cowlings, fenders, panels, body covers, and the like; in boats; in electrical and electrical equipment device housing and covers; as well as other household and personal articles, including, for example, appliance housings such as vacuum cleaner housings, housewares, freezer containers, and crates; lawn and garden furniture; building and construction sheet, including floor coverings and wall coverings; footwear such as shoes, boots and outer shells for ski boots, roller skates and ice skates.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Component (a) in the filled thermoplastic composition of the present invention is a thermoplastic polymer. The thermoplastic polymer can be a homopolymer or a copolymer. Preferably, the thermoplastic polymer is a polyolefin (PO), a polycarbonate (PC), a polystyrene (PS), a polyphenylene oxide (PPO), a styrene and acrylonitrile copolymer (SAN), an acrylonitrile, butadiene and styrene copolymer (ABS), a polyester, a polyamide (e.g., Nylon), a thermoplastic polyurethane (TPU, e.g., PELLATHANETM™ or ISOPLASTTM™ made by The Dow Chemical Company), or blends thereof (e.g., PC/ABS, PC/polyester, PPO/PS, Nylon/PPO, Nylon/PO, PO/PS and the like). Generally the polyolefin polymers which are most frequently used are polyethylene (PE) and polypropylene (PP) made by conventional Ziegler-Natta or metallocene catalysts. Polypropylene is most preferred.
The polypropylene suitable for use in this invention is well known in the literature and can be prepared by known techniques. In general, the polypropylene is in the isotatic form, although other forms can also be used (e.g., syndiotatic or atatic). The polypropylene used for the present invention is preferably a homopolymer of polypropylene or a copolymer, for example, a random or block copolymer, of propylene and an alpha-olefin, preferably a C
2
, or C
4
to C
20
alpha-olefin. The alpha-olefm is present in the polypropylene of the present invention in an amount of not more than 20 percent by mole, preferably not more than 15 percent, even more preferably not more than 10 percent and most preferably not more than 5 percent by mole.
Examples of the C
2
, and C
4
to C
20
alpha-olefins for constituting the propylene and alpha-olefin copolymer include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1 -hexadodecene, 4-methyl-1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, diethyl-1-butene, trimethyl-1-butene, 3-methyl-1-pentene, ethyl-1-pentene, propyl-1-pentene, dimethyl-1-pentene, methylethyl-1-pentene, diethyl-1-hexene, trimethyl-1-pentene, 3-methyl-1-hexene, dimethyl-1-hexene, 3,5,5-trimethyl-1-hexene, methylethyl-1-heptene, trimethyl-1-heptene, dimethyloctene, ethyl-1-octene, methyl-1-nonene, vinylcyclopentene, vinylcyclohexene and vinylnorbornene, where alkyl branching position is not specified it is generally on position 3 or higher of the alkene.
Preferably the polypropylene of the present invention is an isotactic polypropylene having a high degree of crystallinity. A preferable method of determining the degree of crystallinity in polypropylene is by differential scanning calorimetry (DSC). A small sample (milligram size) of the polypropylene is sealed into an aluminum DSC pan. The sample is placed into a DSC cell with a 25 centimeter per minute nitrogen purge and cooled to about −100° C. A standard thermal history is established for the sample by heating at 10° C. per minute to 225° C. The sample is then cooled to about −100° C. and reheated at 10° C. per minute to 225° C. The observed heat of fusion (&Dgr;H
observed
) for the second scan is recorded. The observed heat of fusion is related to the degree of crystallinity in weight percent based on the weight of the polypropylene sample by the following equation:
Crystallinity, percent
=
Δ
H
observed
Δ
H
isotactic
PP
×
100
where the heat of fusion for isotactic polypropylene (&Dgr;H
isotactic PP
), as reported in B. Wunderlich, Macromolecular Physics, Volume 3, Crystal Melting, Academic Press, New Your, 1980, p 48, is 165 Joules per gram (J/g) of polymer.
As defined herein, a high degree of crystallinity, as determined by DSC, is at least about 62 weight percent, more preferably at least about 64 weight percent, even more preferably at least about 66 weight percent, even more preferably at least about 68 weight percent and most preferably at least about 70 weight percent based on the weight of the polypropylene. The degree of crystallinity for the polypropylene as determined by DSC is less than or equal to about 100 weight percent, preferably less than or equal to about 90 wei
Novak Leo R.
Traugott Thomas D.
Dow Global Technologies Inc.
Lee Rip A
Wu David W.
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