Polyolefin compositions having variable density and methods...

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

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C524S440000, C524S441000, C524S494000, C523S218000, C523S219000

Reexamination Certificate

active

06525125

ABSTRACT:

FIELD OF THE INVENTION
The invention is directed generally to polyolefin compositions having variable density properties and to methods of producing and using the same. More specifically, the invention relates to the use of density modulators and, in a preferred form to polymer-based compositions based on dicyclopentadiene (DCPD) and other cyclic olefins comprising such density modulators.
BACKGROUND OF THE INVENTION
During the past 25 years, research efforts have enabled the elucidation of olefin metathesis reactions catalyzed by transition metal complexes. In particular, certain ruthenium and osmium carbene compounds have been identified as effective catalysts for olefin metathesis reactions such as, for example, ring opening metathesis polymerization (ROMP). Examples of such metathesis catalysts have been previously described in, for example, U.S. Pat. Nos. 5,312,940, 5,342,909, 5,728,917, 5,710,298, 5,831,108, and 6,001,909; PCT Publications WO 97/20865, WO 97/29135 and WO 99/51344; in United States Provisional Patent Application No. 60/142,713 filed Jul. 7, 1999 entitled “ROMP Reactions Using Imidazolidine-Based Metal Carbene Metathesis Catalysts;” and by Furstner, Picquet, Bruneau, and Dixneuf in Chemical Communications, 1998, pages 1315-1316, the disclosures of each of which are incorporated herein by reference.
Density-modulated polymer compositions can be advantageous in a variety of applications, especially where “weight” or “balance” of a polymeric part or article is a critical consideration. For example, density-modulated polymers would be useful materials for the production of equipment for the sports, recreation, and marine industries, particularly where dense, heavy articles or, alternatively, low-density, light foam articles are desired. Traditionally, numerous density-modulating additives have been used to effect these changes. However, where these traditional density modulators have been used in conjunction with typical thermoset or thermoplastic resins, numerous limitations or problems have arisen. Traditional thermoset resin systems lack inherent toughness and, once filled with conventional density modulators, become even more brittle in nature. Moreover, the high viscosity of these traditional resins prevents either the high loading of density modulators or the production of void-free articles. Thus, it has not been possible to combine the performance advantages provided by certain physical properties of polymers with the ability to vary the density of the polymer composition over a wide range without dramatically decreasing the practical value by increasing brittleness or void content of the articles produced.
In light of the foregoing, there exists a need for polymer compositions, and articles of made therefrom, which may be formulated to have variable densities for use in a wide range of commercial applications, especially those related to the sports, recreation, and marine industries.
SUMMARY OF THE INVENTION
This invention relates to novel polyolefin compositions having variable density, as well as to methods for producing and using the same. In particular, the invention provides for the inclusion of density modulators, which may be added to polyolefin resins. We have now found that these density modulators permit controllable modulation when used with a selected range of polymeric materials, of the density or “weight” of a resulting polyolefin article. Such modified polyolefin compositions are useful in a variety of applications and products, particularly those in the sports, recreational, and marine fields.
In certain preferred embodiments, the polyolefin compositions of the invention are prepared by the ring-opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) and related cyclic olefins, polymerized with a metal catalyst system. Ruthenium and osmium carbene compounds have been identified as effective catalysts for olefin metathesis reactions such as, for example, ROMP. Such metal carbene metathesis catalysts have been previously described in, for example, U.S. Pat. Nos. 5,312,940, 5,342,909, 5,728,917, 5,710,298, 5,831,108, and 6,001,909; PCT Publications WO 97/20865, WO 97/29135 and WO 99/51344; in United States Provisional Patent Application No. 60/142,713 filed Jul. 7, 1999 entitled “ROMP Reactions Using Imidazolidine-Based Metal Carbene Metathesis Catalysts;” and by Fuirstner, Picquet, Bruneau, and Dixneuf in Chemical Communications, 1998, pages 1315-1316, the disclosures of each of which are incorporated herein by reference.
Examples of olefin monomers that may be polymerized using the aforementioned metathesis catalysts include dicyclopentadiene (DCPD), in addition to other cyclic olefin compounds. Polymer compositions, and articles or parts produced therefrom, are useful in a wide variety of applications because of their unique physical properties and ease of fabrication. In particular, DCPD-based polymer (poly-DCPD) compositions show promise for applications requiring a combination of toughness, hardness, variable density, and/or corrosion resistance. In addition, the low viscosity of DCPD-based compositions makes these resins particularly well-suited to the fabrication of complex shapes and composites.
In preferred embodiments, the invention involves ROMP reactions where olefin (such as DCPD resin) compositions are cast into product molds or infused into a fiber preform. For certain applications, pigments, dyes, antioxidants, flame retardants, toughness modulators, hardness modulators, among other additives, may optionally be included in the polyolefin composition. In its preferred forms, the invention includes two main groups of modified polyolefin compositions: (1) polyolefin compositions that are lighter in density or weight than the unmodified polyolefin resins and (2) polyolefin compositions that are higher in density or weight than the unmodified polyolefin resins. The modulating additives are dispersed in the polyolefin resin matrix to alter various physical properties of the native polyolefin.
Particularly preferred density modulators include, for example, metallic density modulators (in the case of increased-density polyolefin compositions), microparticulate density modulators, such as, for example, microspheres (in the case of increased- or decreased-density polyolefin compositions), and macroparticulate density modulators, such as, for example, glass or ceramic beads (in the case of increased- or decreased-density polyolefin compositions). Metallic density modulators include, but are not limited to, powdered, sintered, shaved, flaked, filed, particulated, or granulated metals, metal oxides, metal nitrides, and/or metal carbides, and the like. Microparticulate density modulators include, but are not limited to, glass, metal, thermoplastic (either expandable or pre-expanded) or thermoset, and/or ceramic/silicate microspheres. Macroparticulate density modulators include, but are not limited to, glass, plastic, or ceramic beads; metal rods, chunks, pieces, or shot; hollow glass, ceramic, plastic, or metallic spheres, balls, or tubes; and the like. Density modulators of the invention may optionally comprise sizings, finishes, coatings, and/or surface treatments to enhance their compatibility with and/or adhesion to the polyolefin matrix resins.
One aspect of the invention is a novel polyolefin composition having variable density properties through the addition of density modulators. Another aspect of the invention is a process for preparing such variable-density polyolefin compositions, wherein the process includes the step of adding to a polyolefin resin various density modulators. A further aspect is an article of manufacture, such as a molded part, comprising the aforementioned polyolefin composition. These and other aspect of the invention will be apparent to one skilled in the art in light of the following detailed description of the preferred embodiments.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention is directed to polyolefin compositions having variable density properties and to methods for t

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