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
2002-06-18
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, C524S445000, C524S446000, C524S447000, C524S412000, C524S528000
Reexamination Certificate
active
06407155
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to intercalated layered materials and, optionally, exfoliates thereof, prepared by contacting, and thereby reacting, a layered material, e.g., a phyllosilicate, such as a smectite clay, with a coupling agent, such as a silane coupling agent, to replace platelet edge —OH groups with —O—Si—R groups; intercalation of an onium ion spacing/compatibilizing agent and co-intercalation of the layered material with an oligomer or polymer, particularly a non-polar polymer, (e.g., as a polyolefin polymer, oligomer or copolymer) for ease of polymer intercalation. The polymer can be intercalated in the form of a polymer or 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 coupling agent reacted and onium ion-intercalated layered material and the oligomer and/or polymer in a mixing or extruding device preferably at or above the polymer melt temperature, to produce the co-intercalated layered material and the nanocomposite.
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 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 reactive 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, hereinafter “CAO 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.
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 an important feature of the present invention, 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.
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. The concentration of coupling agent 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 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 branched, and R
2
, R
3
and R
4
, same or different, are hydrogen or an alkyl aryl or alkyl moiety, preferably a C
1
-C
8
alkyl chain.
Where the intercalant polymer is a polyolefin, in accordance with the preferred embodiment, it is preferred to add 0.2% to 10% modified polyolefin, e.g., maleic anhydride-modified polyolefin, based on the total weight of the polymer, including intercalated polymer and matrix polymer, to increase the interaction between polyolefin and the silane-reacted, onium ion-intercalated layered material. The new silane-reacted, onium ion-intercalated (CAO Material) and polyolefin-intercalated organoclay nanocomposite has improved mechanical properties and heat stability over traditional polyolefin-organoclay nanocomposites, it is theorized due to the silane reaction enabling easier and more complete intercalation of the non-polar polymer between clay platelets for surprisingly better dis
Fay Aaron M.
Lan Tie
Qian Guoqiang
Tomlin Anthony S.
Amcol International Corporation
Cain Edward J.
Marshall Gerstein & Borun
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