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
1999-06-01
2001-05-01
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...
C524S446000, C524S447000
Reexamination Certificate
active
06225394
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to intercalated layered materials and, optionally, exfoliates thereof, prepared by contacting, and thereby intercalating, a layered silicate material, e.g., a phyllosilicate, such as a smectite clay, with an alkyl ammonium onium ion, preferably with an alkoxylated onium ion spacing/coupling agent and co-intercalation of the layered material with a melt of ethylene vinyl alcohol (EVOH) (as polymerizable reactants, or as the EVOH oligomer or polymer) to form nanocomposite materials with new and improved gas (particularly O
2
) barrier properties. The EVOH copolymer can be intercalated in the form of the reactants (ethylene and vinyl acetate polymerizable monomers) or, can be unexpectedly easily intercalated as the EVOH oligomer or polymer by direct compounding, e.g., by combining the onium ion-intercalated layered material and a melt of EVOH in a mixing or extruding device to produce the co-intercalated layered material and the nanocomposite.
The interlaminar spacing of adjacent layers (platelets) of the layered material is expanded at least about 3 Å, preferably at least about 5 Å, to a basal spacing of at least about 13 Å, preferably to at least about 15 Å, and usually to about 18 Åby contacting the layered material with the onium ion spacing/coupling agent for subsequent intercalation with EVOH. The onium ion may be primary, secondary, tertiary or quaternary and preferably is a long chain (C
6
+) alkoxylated onium ion spacing/coupling agent having at least one binding (ion-exchange) site capable of ion-exchanging or replacing Li
+
, Na
+
, K
+
, Ca
+
, Mg
+2
, or other inorganic cations that occur within the interlayer spaces between adjacent layers or platelets of the layered materials. The association of the layered material inorganic cations with the onium ion spacing/coupling agent via ion-exchange enables the conversion of the hydrophilic interior clay platelet surfaces to hydrophobic platelet surfaces. Therefore, polymerizable EVOH oligomers, or polymers, or ethylene and vinyl acetate monomers capable of reacting to form EVOH, can be easily intercalated between adjacent platelets of the layered material, e.g., smectite clay platelets.
In accordance with the preferred embodiment of the present invention, the fully polymerized EVOH polymer having a weight average molecular weight between about 100 and about 5 million, preferably about 1,000 to about 500,000, is intercalated between adjacent platelets of the onium ion-treated layered material, preferably simultaneously with dispersing the intercalate into an EVOH matrix polymer, i.e., by direct compounding of the onium ion-treated layered material with the EVOH polymer melt. The co-intercalation of the onium ions and EVOH, or its monomeric reactants, or EVOH polymerizable oligomers, results in a completely homogeneous dispersion of intercalated layered material and/or exfoliated platelets.
Optionally, the nanocomposite material can be sheared to exfoliate up to 100% of the tactoids or platelet clusters into individual platelets, preferably such that more than 80%; or more than 90% by weight of the layered material can be completely exfoliated into single platelet layers. Quick, easy, and completely homogeneous dispersion of the alkoxylated onium ion/EVOH co-intercalated layered material in the EVOH matrix polymer is achieved and the resulting nanocomposite has unexpected O
2
-impermeability. For example, a film of the EVOH polymer with the layered material, particularly an alkyl ammonium ion-exchanged, preferably alkoxylated onium ion-exchanged, smectite clay can be formed by direct compounding to provide a sheet of the EVOH without any visible intercalate filler that has completely unexpected, extremely low gas permeability. Such films are also effective in reducing the permeability of other gases such as CO
2
, H
2
O, and hydrocarbons, such as gasoline vapors, and the like.
The intercalates of the present invention can be dispersed uniformly into EVOH materials to form EVOH polymer/clay intercalate nanocomposites by direct compounding of the onium ion-intercalated clay with sufficient EVOH for intercalation of the clay to form an EVOH intercalated clay, as a concentrate, that can later be mixed with EVOH and/or other polymeric materials to form a nanocomposite. Alternatively, the onium ion-intercalated clay can be intercalated with monomer reactants that are polymerizable to form EVOH to form the EVOH co-intercalate.
In another embodiment of the present invention, the EVOH intercalates can be dispersed in one or more matrix monomers followed by polymerization of the matrix monomer(s), e.g., ethylene and vinyl acetate, with in-situ polymerization of the monomer reactants to form the polymer, in situ, between the platelets of the layered material, and to form the matrix polymer, e.g., by adding a polymerization initiator or catalyst, to form the nanocomposite material. For example, polymerization initiators or catalysts can be directly incorporated into the monomeric EVOH reactants that are intercalated between platelets of the onium ion-intercalated clay followed by polymerization of the EVOH reactant intercalant monomers that have been intercalated into the clay interlayer galleries. In accordance with an important feature of the present invention, if an intercalant EVOH polymer is intercalated into the onium ion-intercalated clay galleries, the EVOH intercalate can be directly compounded with the pristine matrix polymer, preferably an EVOH matrix polymer, to form a nanocomposite easily, while achieving a nanocomposite material with unexpected of gas (O
2
) impermeability. If the ethylene and vinyl acetate polymerizable intercalant monomers, or a polymerizable EVOH oligomer intercalant is intercalated into the clay galleries, the intercalant(s) can be polymerized together with a desired monomer, oligomer or polymer matrix material, preferably EVOH and the combination then can be compounded to form the nanocomposites.
BACKGROUND OF THE INVENTION AND PRIOR ART
It is well known that phyllosilicates, such as smectite clays, e.g., sodium montmorillonite and calcium montmorillonite, can be treated with organic molecules, such as organic ammonium ions, to intercalate the organic molecules between adjacent, planar silicate layers, for bonding the organic molecules with a polymer, for intercalation of the polymer between the layers, thereby substantially increasing the interlayer (interlaminar) spacing between the adjacent silicate layers. The thus-treated, intercalated phyllosilicates, having interlayer spacings increased by at least 3 Å, preferable at least 5 Å, e.g., to an interlayer (interlaminar) spacing of at least about 10-25 Åand up to about 100 Angstroms, then can be exfoliated, e.g., the silicate layers are separated, e.g., mechanically, by high shear mixing. The individual silicate layers, when admixed with a matrix polymer, before, after or during the polymerization of the matrix polymer have been found to substantially improve one or more properties of the polymer, such as mechanical strength and/or high temperature characteristics.
Exemplary prior art composites, also called “nanocomposites”, are disclosed in published PCT disclosure of Allied Signal, Inc. WO 93/04118 and U.S. Pat. No. 5,385,776, disclosing the admixture of individual platelet particles derived from intercalated layered silicate materials, with a polymer to form a polymer matrix having one or more properties of the matrix polymer improved by the addition of the exfoliated intercalate. As disclosed in WO 93/04118, the intercalate is formed (the interlayer spacing between adjacent silicate platelets is increased) by adsorption of a silane coupling agent or an onium cation, such as a quaternary ammonium compound, having a reactive group which is compatible with the matrix polymer. Such quaternary ammonium cations are well known to convert a highly hydrophilic clay, such as sodium or calcium montmorillonite, into an org
Lan Tie
Psihogios Vasiliki
Tomlin Anthony S.
Amcol International Corporation
Cain Edward J.
Marshall O'Toole Gerstein Murray & Borun
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