Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
2003-02-07
2004-12-07
Kiliman, Leszek B (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C428S325000, C428S327000, C428S402000, C428S403000, C428S404000, C428S407000, C106S436000, C106S472000, C106S474000, C106S478000
Reexamination Certificate
active
06828015
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a composite containing thin film particles having a carbon skeleton, a method for reducing the thin film particles and a process for the production of the composite. More specifically, it relates to a composite containing thin film particles having a carbon skeleton which composite is suitable for various uses such as a high strength material, a material having a small heat-deformation, a material having high barrierability to small molecules or the like, a material having a high thermal conductivity and an electrically-conductive material used for a circuit or the like, a method for reducing the above thin film particles and a process for the production of the above composite.
BACKGROUND OF THE INVENTION
In recent years, searches for materials having high anisotropy of shape and applications thereof are proceeding rapidly. As an anisotropic shape material having carbon atoms as a skeleton, there are known one-dimensional materials such as a graphite fiber or a carbon nanotube being an especially slender graphite fiber and two-dimensional materials such as graphite, graphite fluoride and graphite oxide. Of these, each of graphite, graphite fluoride and graphite oxide is a multi-layer structure matter in which two-dimensional fundamental layers are laminated, and multi-layer structure matters having so many layers are generally known. Concerning graphite oxide, very thin graphite oxide having a small number of layers has been made (for example, N. A. Kotov et al., Adv.Mater., 8,637(1996)). The present inventors also have found a process for producing thin film particles of such graphite oxide (when the number of layers is one, e.g., it is preferred to call it “graphene oxide” (“graphene” is the name for one graphite layer)) in high yield and produced thin film particles having a very small number of layers similar to graphite (when the number of layers is one, it is preferred to call it “graphene”) by reducing the above thin film particles (JP-A-2002-53313). Further, the present inventors have produced especially broad thin film particles, a lamination layer aggregate in which the thin film particles are laminated and broad, and reductants of these (Japanese Patent Application No. 2001-374537, Japanese Patent Application No. 2001-374538).
The fundamental layer of graphite oxide is thought to have a structure in which acidic hydroxyl groups, etc., are bonded to both sides of a carbon skeleton (composed of sp
3
carbon and sp
2
carbon, sp
3
carbon is larger in amount) having a thickness equivalent to one carbon atom or two carbon atoms (for example, T. Nakajima et al., Carbon, 26, 357(1988); M. Mermoux et al., Carbon, 29, 469(1991)). When the thickness of the carbon skeleton is equivalent to the size of one carbon atom, and hydroxyl groups are bonded to both sides of the carbon skeleton and interlayer water is remarkably little in amount, the thickness of the fundamental layer is 0.61 nm. Further, when graphite oxide has a high oxidation degree and is dried sufficiently, the content of oxygen in the graphite oxide is approximately 30 to 40 wt %.
Although the above graphite oxide having an oxygen content of approximately 30 to 40 wt % generally has a high resistivity of about 10
6
to 10
8
&OHgr;·cm and has remarkably low electric conductivity, it is known that the above graphite oxide comes to have an electronic state having many sp
2
bonds analogous to graphite by partial or complete reduction and is thus increased in electric conductivity. The graphite oxide increased in electric conductivity by the reduction can be applied, as a semiconductor or a conductor, in various fields such as semiconductor devices, wiring materials, fillers for anti-electrification and anti-electrostatic, so that it is remarkably useful.
The present inventors have disclosed thin film particles which are obtained by oxidizing graphite and which have a thickness of 0.4 to 10 nm and a planar direction size of 20 nm or more, are dispersible in a liquid having a relative dielectric constant of 15 or more and have a carbon skeleton in JP-A-2002-53313. In the specification thereof, the present inventors indicate that heating, a reducing agent or an electrode reaction can reduce the thin film particles. Further, the present inventors have disclosed large-sized thin film particles having a carbon skeleton of a planar-direction size of 500 &mgr;m or more in Japanese Patent Application No. 2001-374537 and similarly indicated that heating, a reducing agent or an electrode reaction can reduce these thin film particles too.
The above thin film particles of graphite oxide (to be referred to as “oxidized form thin film particles” hereinafter) are increased in electric conductivity by partial or complete reduction, as described above. In particular, as a general behavior of graphite oxide, reduction by heating can convert even the inside of a multi-layer particle into a structure similar to that of graphite. It is known that, when heating is carried out in a state where a plurality of the particles are bonded to each other, intermolecular forces arise in an interlayer inside each multi-layer particle or between a plurality of the particles so that a macroscopic shape like a general graphite film can be provided (J. Maire et al., Carbon, 6,555(1968)). The oxidized form thin film particles are converted into reduced form thin film particles by similar heating (JP-A-2002-53313).
Here, when the thin film particles are completely reduced, each fundamental layer of the thin film particles becomes almost graphite's fundamental layer (graphene). When the thin film particles are multi-layer particles, the interlayer distance is almost equal to the interlayer distance of graphite. However, each multi-layer particle has a structure of a turbostratic tendency in which the mutual positional relationship of respective layers is more turbulent than that of graphite. Further, when the thin film particles are partially reduced, oxygen and the like remain in each fundamental layer and its interlayer distance becomes larger than that of graphite.
The above oxidized form and reduced form thin film particles can be called “graphite oxide nanofilm” (“graphene oxide nanofilm”, when the number of layers is one), when the fraction of oxygen is high. When the oxygen fraction is low or no oxygen is contained, the thin film particles can be called “graphite nanofilm” (“graphene nanofilm”, when the number of layers is one). Further, uniformly, these thin film particles are respectively called an oxidized form single-layer carbon nanofilm or multilayer carbon nanofilm and a reduced form single-layer carbon nanofilm or multilayer carbon nanofilm. Using the name of “carbon nanofilm” can prevent any confusion from being caused by calling the thin film particles having a turbostratic tendency “graphite”, as described above.
Concerning such oxidized form and reduced form thin film particles, there have been synthesized some composites with a macromolecule. These composites are intercalation compounds of the thin film particles and the macromolecule. Although their interlayer distances (interval of a fundamental period of a layer structure) depend upon a mixing ratio or additives at the time of synthesis, it is reported that the interlayer distance of a composite with poly(ethylene oxide) is 1.28 nm (Y. Matsuo et al., Carbon, 34, 672(1996), polyethylene oxide is added), that the interlayer distance of a composite with polyaniline is 1.2 nm (S. Higashika et al., Carbon, 37, 351(1999), aniline (monomer) is polymerized in interlayer spaces), and that the interlayer distance of a composite with poly(vinyl acetate) is 1.15 nm (P. Liu et al., Carbon, 37, 2073(1999), vinyl acetate (monomer) is polymerized in interlayer spaces).
However, each of these synthesis examples contains a relatively high fraction of the thin film particles. These examples target a composite having high periodicity, the whole of which is an intercalation compound. In contrast, there have not been reported a composite with
Goto Takuya
Hirata Masukazu
Horiuchi Shigeo
Iwasaki Ryu
Takenaka Kouji
Kiliman Leszek B
Mitsubishi Gas Chemical Company Inc.
Wenderoth , Lind & Ponack, L.L.P.
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