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
1999-11-16
2001-11-27
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...
C501S148000, C524S446000, C524S447000
Reexamination Certificate
active
06323270
ABSTRACT:
FIELD OF THE INVENTION
The invention herein described relates generally to nanocomposites and/or blends of benzoxazines (monomer, oligomer and/or polymer) and clays. The invention described relates to nanocomposites and/or blends of benzoxazines and clay in which spacing between the platelet structure of the clay is increased by the benzoxazine compounds, thus indicating that the benzoxazine is either encompassing the clay particles or being inserted in between the platelets of the clay.
BACKGROUND OF THE INVENTION
Nanocomposites have recently attracted considerable attention as a means of enhancing polymer properties. In general there are two types of nanocomposite structures, intercalated and exfoliated. Such structures are classified according to the separation of the clay layers. In an intercalated nanocomposite, extended polymer chains are inserted between the host clay layers resulting in a well ordered multilayer nanostructure where the insertion of a polymer into the clay structure occurs in a crystallographically regular fashion regardless of the clay to polymer ratio. Intercalation of various monomers into the silicate galleries, followed by in-situ polymerization, yields highly oriented multi-layers consisting of the polymer alternately stacked with the layers of the host.
The host layers of exfoliated nanocomposites are dispersed in a continuous polymer matrix. The individual one nanometer thick clay layers of an exfoliated nanocomposite are separated by average distances that depend on loading. Exfoliated polymer-clay nanocomposites form when adjacent clay nanolayers are separated by a distance that precludes the possibility of interlayer interaction through the association of gallery cations.
For many technologically important polymers, the monomer intercalation/exfoliation approach is limited because a suitable monomer is not always available. However, various monomers have been used, yielding linear and crosslinked polymer matrices. This technique has been investigated with a number of vinyl monomers including tetrafluoroethylene, cis- and trans- butene, butadiene, 4-vinyl pyrridine, acrylamide, methyl methacrylate, acrylonitrile, and styrene. However, because the adsorption of monomer molecules between clay layers or lamellae is dependent on the dipole moment of the monomer, low yields are generated when any one of the above polymers are physically inserted into clay. The most successful polymerizations within silicate galleries tend to proceed by ring-opening mechanisms, for example the well known epoxy and Nylon-6 nanocomposites.
The use of high performance, high temperature polymers as the organic phase in nanocomposites presents special problems. One of the challenges in the area of high performance polymers is to obtain significant improvements in these classes of polymers, since many already have superb thermal and mechanical properties.
Polyimides are an example of a class of high performance polymers that have been used as matrices for nanocomposites. Since polyimides are used largely for microelectronics it is desirable to reduce the coefficient of thermal expansion, the amount of moisture absorption and the dielectric constant. The preparation of polyimide nanocomposites has shown a significant increase in the gas barrier properties and a decrease in the thermal conductivity. However, the water absorption ratio has not been improved remarkably, and mechanical properties of such nanocomposites have not yet been examined. Additionally, the thermal properties of a polyetherimide, specifically its fire retardant nature, has been examined in both intercalated and exfoliated nanocomposites. Both structures exhibited a delayed decomposition temperature compared to the unfilled polymer, and the immiscible hybrid containing the same amount of silicate showed no improvement, suggesting that formation of the nano-structure is responsible for the increase in the thermal stability.
Preparation of nanocomposites with “traditional” phenolic resins tends to produce an undesirable amount of water during polymerization, have poor processability, require the use of a strong catalyst(s), and have poor mechanical design flexibility.
Thus, there is a need for a compound which can be used to produce intercalated, exfoliated and intercalated/exfoliated nano-structures which possess superior processability, do not require the use of a strong catalyst(s), and have superior mechanical design flexibility. Additionally, there is a need for a monomer that can produce both intercalates and exfoliates in an organo-clay system and which upon polymerization does not produce an undesirable amount of water.
SUMMARY OF THE INVENTION
The invention herein described relates generally to nanocomposites and/or blends of benzoxazines (monomer, oligomer and/or polymer) and clays. More specifically, the invention described herein relates to clay which is dispersed in polybenzoxazines yielding either an intercalated, exfoliated or combination nanocomposite structure.
In accordance with one aspect of the invention, a nanocomposite composition comprises clay and an effective amount of a benzoxazine monomer, oligomer, and/or polymer.
In accordance with another aspect of the invention, the presence of the benzoxazine monomer, oligomer, and/or polymer in the clay results in an at least about 5% increase in the spacing between the platelets of the clay. Alternatively, the presence of the benzoxazine monomer, oligomer, and/or polymer in the clay results in at least about 5 wt. % of the clay being exfoliated.
In another aspect of the invention, the benzoxazine monomer, oligomer, and/or polymer is either bis(3,4-dihydro-2H-3-phenyl-1,3-benzoxazinyl) isopropane or is formed therefrom.
In another aspect of the invention, a nanocomposite composition comprises clay and an effective amount of a benzoxazine monomer, oligomer, and/or polymer wherein the benzoxazine monomer, oligomer, and/or polymer is either bis(3,4-dihydro-2H-3-phenyl-1,3-benzoxazinyl)isopropane or is formed therefrom and wherein the presence of the benzoxazine monomer, oligomer, and/or polymer in the clay results in an at least about 5% increase in the spacing between the platelets of the clay.
In another aspect of the invention, a method for preparing a nanocomposite clay composition comprises the steps of: (A) providing a mixture comprising (1) benzoxazine oligomer or polymer and clay or (2) at least one phenolic compound, at least one primary amine, at least one aldehyde and clay; and (B) curing the mixture to produce a nanocomposite composition.
In another aspect of the invention, step (B) comprises the steps of: (B-1) curing the reaction mixture at a temperature of about 140° C.; (B-2) curing the reaction mixture at a temperature of about 160° C.; and (B-3) curing the reaction mixture at a temperature of about 190° C.
In another aspect of the invention, a method of forming a nanocomposite of clay with at least one benzoxazine compound comprises blending the clay with a benzoxazine monomer, oligomer, and/or polymer or benzoxazine precursors or combinations thereof with the benzoxazine component being in a liquid form such that the benzoxazine component can enter between the platelets of the clay under blending conditions.
REFERENCES:
patent: 4105578 (1978-08-01), Finlayson
patent: 4450095 (1984-05-01), Finlayson
patent: 5514734 (1996-05-01), Maxfield et al.
patent: 5830528 (1998-11-01), Beall et al.
patent: 6057396 (2000-05-01), Lan et al.
Agag, T; Takeichi, T; J of Polymer Science “Polybenzoxazine-Montmorillonites Hybrid Nanocomposites: Synthesis and Characterization” vol. 41 (2000) pp 7038-7090.
Cain Edward J.
Case Western Reserve University
Lee Katarzyna W.
Renner Otto Boisselle & Sklar
LandOfFree
Polybenzoxazine nanocomposites of clay and method for making... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polybenzoxazine nanocomposites of clay and method for making..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polybenzoxazine nanocomposites of clay and method for making... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2580156