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
1999-12-01
2002-05-07
Cain, Edward J. (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...
C524S447000, C501S148000
Reexamination Certificate
active
06384121
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a nanocomposite comprising a matrix polymer, a functionalized polymer or oligomer and a clay material. This invention also relates to articles produced from the nanocomposite and processes for producing the nanocomposite.
BACKGROUND OF THE INVENTION
There is much interest in layered, clay-based polymer nanocomposites because of the improved properties exhibited by the nanocomposites. It is desirable to maximize delamination of the platelet particles into individual platelets in order to maximize some property improvements, including barrier improvements, and to minimize deleterious effects on some properties including elongation-at-break. Ideally, the clay is exfoliated into particles with size less than about 100 nm in order to achieve clarity in the polymer that is comparable to the clay-free polymer. To date, the only polymer/clay nanocomposites that meet this expectation are prepared by incorporation of organically treated clays during synthesis of the polymer from monomer.
It is widely known, however, that the amount of clay that can be admixed in a polymer and still exhibit exfoliation of the layered clay is limited and some mechanical properties, such as elongation-at-break, are often reduced considerably upon the addition of the clay. Researchers recognized the value of inventing melt compounding processes that provide exfoliated polymer/platelet particle composites, namely more versatility of polymer choice and clay loading and the potential for cost savings. However, the melt compounding processes explored to date do not provide sufficient exfoliation of the platelet particles.
Polyesters such as poly(ethylene terephthalate) (PET) are widely used in bottles and containers which are used for carbonated beverages, fruit juices, and certain foods. Useful polyesters have high inherent viscosities (I.V.s) that allow polyesters to be formed into parisons and subsequently molded into containers. Because of the limited barrier properties with regard to oxygen, carbon dioxide and the like, PET containers are not generally used for products requiring long shelf life. For example, oxygen transmission into PET bottles that contain beer, wine and certain food products causes these products to spoil. There have been attempts to improve the barrier properties of PET containers by use of multilayer structures comprising one or more barrier layers and one or more structural layers of PET. However, multilayer structures have not found wide use and are not suitable for use as a container for beer due to the high cost, the large thickness of the barrier layer required, and poor adhesion of the barrier layer with the structural layer.
There are examples in the literature of polymer/clay nanocomposites prepared from monomers and treated clays. For example, U.S. Pat. No. 4,739,007 discloses the preparation of Nylon-6/clay nanocomposites from caprolactam and alkyl ammonium treated montmorillonite. U.S. Pat. No. 4,889,885 describes the polymerization of various vinyl monomers such as methyl methacrylate and isoprene in the presence of sodium montmorillonite
Some patents describe the blending of up to 60 weight percent of intercalated clay materials with a wide range of polymers including polyamides, polyesters, polyurethanes, polyearbonates, polyolefins, vinyl polymers, thermosetting resins and the like. Such high loadings with modified clays are impractical and useless with most polymers because the melt viscosities of the blends increase so much that they cannot be molded.
WO 93/04117 discloses a wide range of polymers melt blended with up to 60 weight percent of dispersed platelet particles. WO 93/04118 discloses nanocomposite materials of a melt processable polymer and up to 60 weight percent of a clay that is intercalated with organic onium salts. The use of functionalized polymers in the melt blending operation is neither contemplated nor disclosed.
U.S. Pat. No. 5,552,469 describes the preparation of intercalates derived from certain clays and water-soluble polymers such as polyvinyl pyrrolidone, polyvinyl alcohol, and polyacrylic acid. Although the specification describes a wide range of thermoplastic resins including polyesters and rubbers that can be used in blends with these intercalates, there are no examples teaching how to make such blends. The use of ammonium containing materials is specifically excluded; thus, the use of ammonium functionalized polymers is neither contemplated nor disclosed.
The use of a hydroxy functionalized polypropylene oligomer and an organoclay in the preparation of a polypropylene/clay nanocomposite is disclosed by A. Usuki, M. Kato, T. Kurauchi,
J. Appl. Polym. Sci. Letters,
15, 1481 (1996). The use of a maleic anhydride-modified polypropylene oligomer and a stearylammonium-intercalated clay in the preparation of a polypropylene/clay nanocomposite is disclosed by M. Kawasumi, N. Hasegawa, M. Kato, A. Usuki, and A. Okada,
Macromolecules,
30, 6333 (1997). The use of ammonium-functionalized polymers or oligomers is neither contemplated nor disclosed.
JP Kokai patent no. 9-176461 discloses polyester bottles wherein the polyester contains unmodified sodium montmorillonite. Incorporation of the clay into the polyester by melt compounding is disclosed; however, the use of functionalized polymer was neither contemplated nor disclosed.
The following references are of interest with regard to chemically modified organoclay materials: U.S. Pat. Nos. 4,472,538; 4,546,126; 4,676,929; 4,739,007; 4,777,206; 4,810,734; 4,889,885; 4,894,411; 5,091,462; 5,102,948; 5,153,062; 5,164,440; 5,164,460; 5,248,720; 5,382,650; 5,385,776; 5,414,042; 5,552,469; WO Pat. Application Nos. 93/04117; 93/04118; 93/11190; 94/11430; 95/06090; 95/14733; D. J. Greenland, J. Colloid Sci. 18, 647 (1963); Y. Sugahara et al., J. Ceramic Society of Japan 100, 413 (1992); P. B. Massersmith et al., J. Polymer Sci.: Polymer Chem., 33, 1047 (1995); C. O. Sriakli et al., J. Mater. Chem. 6, 103(1996).
SUMMARY OF THE INVENTION
This invention seeks to meet the need for a melt compounding process that provides polymer/clay nanocomposites with sufficient exfoliation for improved properties and clarity for commercial applications, including film, bottles, and containers. The polymer nanocomposite materials of this invention are useful for forming packages that have improved gas barrier properties. Containers made from these polymer composite materials are ideally suited for protecting consumable products, such as foodstuffs, soft drinks, and medicines. This invention also seeks to provide a cost-effective method for producing layers with sufficient oxygen barrier and clarity for wide spread applications as multilayer bottles and containers, including beer bottles.
As embodied and broadly described herein, this invention, in one embodiment, relates to a polymer-clay nanocomposite comprising (i) a melt-processible matrix polymer, (ii) a layered clay material, and (iii) a matrix polymer-compatible functionalized oligomer or polymer.
In another embodiment, this invention relates to a polymer-clay nanocomposite comprising (i) a melt-processible matrix polymer, and incorporated therein (ii) a concentrate comprising a layered clay material and a matrix polymer-compatible functionalized oligomer or polymer.
In another embodiment, this invention comprises a process comprising the steps of (i) forming a concentrate comprising a layered clay material and a functionalized oligomer or polymer, and (ii) melt mixing the concentrate with a melt-processible matrix polymer to form a polymer-clay nanocomposite.
In yet another embodiment, this invention comprises a process comprising the step of melt mixing a layered clay material, a functionalized oligomer or polymer, and a melt-processible matrix polymer to form a polymer-clay nanocomposite material.
Additional advantages of the invention will be set forth in part in the detailed description, including the examples which follow, and in part will be obvious from the description, or may be learned by practice of
Barbee Robert Boyd
Gilmer John Walker
Matayabas, Jr. James Christopher
Turner Sam Richard
Cain Edward J.
Eastman Chemical Company
Graves, Jr. Esq. Bernard J.
Lee K. Wyroszebski
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