Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Reexamination Certificate
2000-03-28
2002-07-16
Wu, Shean C. (Department: 1756)
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
C252S299670, C524S539000, C524S540000, C528S173000, C528S176000, C528S180000, C528S272000
Reexamination Certificate
active
06419851
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to melt processable liquid crystalline terpolyesters and a process for the preparation thereof. The terpolyesters of the invention have the structure shown in formula I below:
The terpolyesters prepared by the process of the present invention are poly(4-phenylene naphthalene-2,6-carboxylate-co-8(3-oxyphenyl)octanoate), poly(4-phenylene, 2-methoxynaphthalene-2,6-carboxylate-co-8(3-oxyphenyl)octanoate), poly(4-phenylene2-phenyl naphthalene-2,6-carboxylate-co-8(3-oxyphenyl)octanoate) and related terpolyesters. The terpolyesters prepared by the process of the present invention are liquid crystalline polymers which can be used in electronics (eg. surface mount units, connectors, printing wiring boards etc. where low coefficient of thermal expansion and low dielectric properties are required), in computer fields, in industry for making chemically resistant parts (eg. tower packing saddles to replace ceramics). The industries to which the invention can apply are plastic industries/electronic industries/computer industries.
BACKGROUND OF THE INVENTION
Thermotropic liquid crystalline terpolyesters obtained from rigid monomers, such as 4-hydroxybenzoic acid are intractable, insoluble and not processable because they decompose prior to melting and their transition temperatures are too high for the existing equipment to process them. (A. I. Isayev, T. Kyu and S. Z. D. Cheng,
Liquid Crystalline Polymer Systems: Technological Advances,
American Chemical Society, Washington, D.C., 1996; H. Stegemeyer, Guest Ed.,
Liquid Crystals,
in Topics in Physical Chemistry (Eds. H. Baumgartel, E. U. Franck and W. Grunbein), Vol. 3, Steinkopff Darmstadt, Springer, New York, 1994; L. L. Chapoy, Ed.: “
Recent Advances in Liquid Crystalline Polymers”
Elsevier, London, 1985 A. Blumstein (Ed), Polymeric Liquid Crystals, Plenum Press, New York (1985); C. Noel and P. Navard,
Progr. Polym. Sci.,
16, 55-110 (1991); Jan Frank, Zbigniew J. Jedlinski and J. Majnus in Hand Book of Polymer Synthesis, H. R. Kricheldorf (Ed), (1991); W. J. Jackson, Jr. and H. F. Kuhfuss,
J. Appl. Polym. Sci.,
25, 1685 (1985); A. J. East, L. F. Charbenneau and G. W. Calundann,
Mol. Cryst. Liq. Inc. Non Linear Opt,
157, 615 (1988); A. Roviello and A. Sirigu,
J. Polym. Sci. Polym. Lett. Edn.,
13, 455 (1975); C. K. Ober, J. I. Jin and R. W. Lenz,
Adv. Polym. Sci.,
13, 103 (1984); A. Blumstein, K. N. Sivaramakrishnan, S. B. Cloughand R. B. Blumstein,
Mol. Cryst. Liq. Cryst.
(
Lett
), 49, 255 (1979); H. R. Kricheldorf and L. G. Wilson,
Macromolecules,
27, 1669 (1994); P. K. Bhowmilk and H. Han,
J. Polym. Sci. Part A: Polym. Chem.
33, 415 (1995); V. Percec and H. Oda,
J. Polym. Sci. Part A: Polym. Chem.
33, 2359 (1995); J. Economy and K. Goranov,
Advances in Polymer Science, Vol.
117, High Performance Polymers, Springer verlag, Berlin, Heidelberg, 1994; C. K. S. Pillai, D. C. Sherrington and A. Sneddon,
Polymer,
33, 3968 (1992); M. Saminathan, C. K. S. Pillai and C. Pavithran,
Macromolecules,
26, 7103 (1993); J. D. Sudha, C. K. S. Pillai and S. Bera,
J. Polym. Mater.,
13, 317 (1996); H. Zhang, G. R. Davies and I. M. Ward,
Polymer,
33, 2651 (1992)).
There have been a large number of attempts to bring down the transition temperatures to a processable range (W. J. Jackson, Jr. and H. F. Kuhfuss,
J. Appl. Polym. Sci.,
25, 1685 (1985); A. J. East, L. F. Charbenneau and G. W. Calundann,
Mol. Cryst. Liq. Inc. Non Linear Opt,
157, 615 (1988); A. Roviello and A. Sirigu,
J. Polym. Sci. Polym. Lett. Edn.,
13, 455 (1975); C. K. Ober, J. J. Jin and R. W. Lenz,
Adv. Polym. Sci.,
13, 103 (1984); A. Blumstein, K. N. Sivaramakrishnan, S. B. Ceough and R. B. Blumstein,
Mol. Cryst. Liq. Cryst.
(
Lett
). 49, 255 (1979); H. R. Kricheldorf and L. G. Wilson,
Macromolecules,
27, 1669 (1994); P. K. Bhowmik and H. Han,
J. Polym. Sci. Part A: Polym. Chem.
33, 415 (1995); V. Percec and H. Oda,
J. Polym. Sci. Part A: Polym. Chem.
33, 2359 (1995); J. Economy and K. Goranov,
Advances in Polymer Science,
Vol. 117, High Performance Polymers, Springer verlag, Berlin, Heidelberg, 1994; C. K. S. Pillai, D. C. Sherrington and A. Sneddon,
Polymer,
33, 3968 (1992)). A number of chemical approaches have been devised to arrive at structures that have lower transition temperatures and lower symmetries. These approaches involve disrupting the ordered structures of the homopolyesters by introducing chain disruptors such as flexible unit, a kink structure, or crank shaft structures etc. or by copolymerising with suitable comonomers that bring down the transition temperatures (W. J. Jackson, Jr. and H. F. Kuhfuss,
J. Appl. Polym. Sci.,
25, 1685 (1985); A. J. East, L. F. Charbenneau and G. W. Calundann,
Mol. Cryst. Liq. Inc. Non Linear Opt,
157, 615 (1998); A. Roviello and A. Sirigu,
J. Polym. Sci. Polym. Lett. Edn.,
13, 455 (1975); C. K. Ober, J. J. Jin and R. W. Lenz,
Adv. Polym. Sci.,
13, 103 (1984); A. Blumstein, K. N. Sivaramakrishnan, S. B. Clough and R. B. Blumstein,
Mol. Cryst. Liq. Cryst.
(
Lett
), 49, 255 (1979); H. R. Kricheldorf and L. G. Wilson,
Macromolecules,
27, 1669 (1994); P. K. Bhowmilk and H. Han,
J. Polym. Sci. Part A: Polym. Chem.
33, 415 (1995); V. Percec and H. Oda,
J. Polym. Sci. Part A: Polym. Chem.
33, 2359 (1995); J. Economy and K. Goranov,
Advances in Polymer Science, Vol.
117, High Performance Polymers, Springer verlag, Berlin, Heidelberg, 1994; C. K. S. Pillai, D. C. Sherrington and A. Sneddon,
Polymer,
33, 3968 (1992)). A number of copolyesters have thus been prepared out of which a few commercial polymers such as Vectra®, and Xydar®, are well known. It is, however, now realised that these copolyesters still have a processing temperature above 300° C. and hence require newer methods or structures to overcome this problem. It is well known that introduction of disruptors such as a “kink” or flexible segments brings down the transition temperature of liquid crystalline polyesters to a processable range (J. Economy and K. Goranov,
Advances in Polymer Science, Vol.
117, High Performance Polymers, Springer verlag, Berlin, Heidelberg, 1994; A. I. Isayev, T. Kyu and S. Z. D. Cheng,
Liquid Crystalline Polymer Systems: Technological Advances,
American Chemical Society, Washington, D.C., 1996). It has been shown that copolymerisation of hydroxy benzoic acid with comonomers having kink or flexible structures gives rise to decrease in the transition temperatures. Although a variety of comonomers containing such structural features have been employed for the synthesis of liquid crystalline copolyesters, use of a comonomer having both a kink and flexible segment built into the same molecule is rare. 8(3-hydroxyphenyl)octanoic acid is, thus, a comonomer having both kink and flexible segments in its structure which when copolymerised with hydroxy benzoic acid gave a transition temperature as low as 256° C. (C. K. S. Pillai, D. C. Sherrington and A. Sneddon,
Polymer,
33, 3968 (1992)); However, it was noted that this polymer although liquid crystalline, decompose before melting (Rajalekshmi, M. Saminathan, C. K. S. Pillai and C. P. Prabhakaran, J. Polym. Sci., Polym. Chem., 34, (2851) 1996). It was therefore thought that appropriate substitution in the phenolic ring may give rise to meltable polymers and hence expected to bring down the transition temperature when copolymerised stands a significant chance for contributing to solving this problem. The drawbacks of the currently marketed liquid crystalline polyesters are that polyesters of 4-hydroxy benzoic acid do not form a melt below its decomposition temperature and liquid crystalline copolyesters like 4-hydroxy benzoic acid/polyethylene terepthalate system (Eastman X76) has several shortcomings in that the heat distortion temp is low (<90° C.) and the thermal stability is low because esters of aliphatc diols decompose above 300° C. via cis-beta elimination to yield olefins. Besides at mole ratios 4-hydroxybenzoic acid/polyethylene terepthalate greater than 1.5:1.0, heterogeneous materials
Pillai Chennakkattu Krishna Sadasivan
Prasad Vadakkethonippurathu Sivankutty Nair
Vijayanathan Veena
Council of Scientific and Industrial Research
Ladas & Parry
Wu Shean C.
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