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
2000-03-01
2002-10-08
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...
C523S215000, C523S216000, C524S446000, C524S447000, C524S492000
Reexamination Certificate
active
06462122
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to intercalated layered materials and, optionally, exfoliates thereof, prepared by intercalating a layered material, e.g., a phyllosilicate, such as a smectite clay, with polypropylene and maleic anhydride-modified polypropylene intercalants. The intercalated layered material, in the form of a concentrate, is combined with a polypropylene matrix polymer since the addition of polypropylene matrix polymer, after shearing the concentrate for exfoliation, avoids degradation of the later added polypropylene matrix polymer, added after shearing of the concentrate. The polypropylene and maleic anhydride-modified polypropylene polymer can be intercalated in the form of a polymer or an oligomer capable of polymerization to form the polymer, (e.g., an ethylene oligomer or polymer and/or a propylene oligomer or polymer and/or copolymers thereof) or, can be unexpectedly easily intercalated as the oligomer or polymer by direct compounding, e.g., by combining the polypropylene oligomers and/or polymers in a mixing or extruding device at or above the polypropylene polymer melt temperature, to produce the intercalated layered material and, subsequently, the nanocomposite by addition of matrix polypropylene polymer.
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 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, preferably at least 5 Å, e.g., to an interlayer (interlaminar) spacing of at least about 10-25 Å and 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, e.g., a polyamide—see U.S. Pat. Nos. 4,739,007; 4,810,734; and 5,385,776—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 (exfoliated platelets) 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 organophilic clay capable of sorbing organic molecules.
Maxfield U.S. Pat. No. 5,514,734 ('734) discloses intercalation of clay with both a coupling agent (silane, titanate or zirconate) and onium ions together with in-situ polymerization of a nylon polymer precursor, such as polymerizable nylon monomers, e.g., &egr;-caprolactam, capable of in-situ polymerization to form a polymer that is reactive with the coupling agent to tether the polymer to the clay platelets. In accordance with the present invention, a coupling agent-reacted and onium compound-intercalated layered silicate material is polymer melt processed for unexpectedly better dispersibility of the exfoliated platelets throughout a matrix polymer, particularly non-polar matrix polymers, such as polyolefins, especially polypropylene. In accordance with the present invention, the coupling agent preferably is not reactive with the matrix polymer, so that the matrix polymer is not tethered to the clay platelets. The Maxfield '734 patent is hereby incorporated by reference for its disclosure of coupling agents useful in accordance with the present invention.
OPTIONAL COUPLING AGENT REACTION
Edges of clay layered materials are replete with hydroxy groups (—OH) that make it extremely difficult to intercalate non-polar and low polarity oligomers and polymers. In accordance with the preferred embodiment of the present invention, as disclosed in copending application 28682/10296 filed concurrently herewith, it has been found that by reacting the —OH groups at the edges of clay platelets with a coupling agent, to form coupling agent covalent bonds at the clay edges, the clay becomes much more receptive to intercalation of such non-polar and low polarity oligomers and polymers, such as ethylene and propylene homopolymers and copolymers. It should be understood, however, that it is not essential to react the layered material edges with a coupling agent in accordance with the present invention since polyolefin intercalant(s) can be intercalated without the coupling agent reaction, particularly when incorporating a relatively small percentage, e.g., about 1-9% by weight, preferably about 1% to about 5% by weight, of maleic anhydride-modified polypropylene in addition to the polypropylene intercalant.
Useful coupling agents include those selected from the group consisting of silanes, titanates, aluminates, zirconates, and mixtures thereof; particularly the organosilanes, organotitanates, organoaluminates and/or organozirconates. The coupling agent(s) can be reacted with the —OH functionalities at the edges of the layered material platelets by contacting the layered material, before, during, or after onium ion intercalation, with the coupling agents, in the form of a gas, neat liquid, finely divided (e.g., non-colloidal) solid, or solute in a solvent. While onium ion intercalation is preferred, it should be understood that onium ion intercalation also is not necessary in accordance with the present invention when maleic anhydride-modified polypropylene is incorporated into the clay together with the polypropylene. The concentration of coupling agent, when used, should be at least about 0.1%, preferably in the range of about 0.1% to about 10% by weight, more preferably in the range of about 0.5% to about 6% by weight, and most preferably about 1% to about 4% by weight, based on the dry weight of the layered material. The preferred coupling agents have a structure as follows:
wherein R
1
is an organic radical, preferably an alkyl radical or an amine radical, bonded directly to the Si, Ti, Zr or Al atom (x) and at least one of R
2
, R
3
and R
4
is a radical containing a functionality, preferably an organic functionality, capable of a condensation reaction with a hydrogen from the —OH groups at the edges of the layered material, preferably selected from H, halogen, alkoxy, acyloxy and amine.
The —OH reaction of the coupling agent, e.g., silane, can be accomplished by either adding the silane to a dry onium-intercalated clay, i.e., organoclay, or by adding the silane to a water slurry of the organoclay, followed by removal of by-products and solvent during heat treatment. Alternatively, the silane also be added to the polymer-organoclay nanocomposite by integral blend methods. In this method, undiluted silane is added to the polymer either before or after introduction of the onium-intercalated clay or organoclay. It is preferable to add the silane before introduction of the clay because this allows for better dispersion and distribution of the silane into the polymer.
In addition to platelet edge —OH reaction with a coupling agent, the layered material also is intercalated with onium ions, e.g., ammonium ions, having a general structure of:
Where R
1
is a C
2
-C
22
alkyl chain, straight chain or branche
Fay Aaron M.
Lan Tie
Qian Guoqiang
Tomlin Anthony S.
AMCOL International Corporation
Cain Edward J.
Marshall Gerstein & Borun
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