Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Reexamination Certificate
2000-03-28
2002-06-25
Wu, Shean C. (Department: 1756)
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
C252S299640, C252S299650, C252S299660, C524S176000, C524S193000, C524S194000, C528S219000
Reexamination Certificate
active
06409937
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to melt processible thermotropic liquid crystalline terpolyesters and processes for the preparation thereof. The terpolyesters of the invention have the structure shown in formula I
The terpolyesters prepared by the process of the present invention are poly (4-phenylene terephthalate-co-oxyphenyl acetate/propionate)s, poly (4,4′-biphenylene terephthalate-co-oxyphenyl acetate/propionate)s, poly (2,6-naphthylene terephthalate-co-oxyphenyl acetate/propionate)s and are liquid crystalline polymers that 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 invention can be applied in plastic, electronics and 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. (Fr. 1568 152 (May 23, 1969), Carborundum Co., invs.: J. Economy, B. E. Novak; Chem. Abstr. 72, 13412x (1970); Ger. Offen, 2025948, (Dec. 3, 1970), Carborundum Co., invs.: J. Economy, S. G. Cottis, B. E. Novak: Chem. Abstr. 74, 54559k (1971); U.S. Pat. No. 3,962,314 (Jun. 8, 1976), Carborundum Co., invs. J. Economy, S. G. Cottis, B. E. Novak; Chem. Abstr. 85, 193510c (1976) Ger. Offen. 2157696, (Jun. 15, 1976), Carborundum Co., invs.: J. Economy, S. G. Cottis, B. E. Novak: Chem. Abstr. 77, 140738m (1972); U.S. Pat. No. 2,728,747 (Dec. 27, 1955), General Mills Inc., invs.: D. Aelony, M. M. Renfrew; Chem. Abstr. 50, 6098c (1956); Jap.7400397 (Jan. 5, 1974), Mitsubishi Rayon Co., invs.: K. Chimurva, S. Takashima, K. Tamuera; Chem. Abstr. 81, 14001k (1974), Ger. Offen 2907613 (Sep. 4, 1980), BASF, invs.: H. R. Kricheldorf, G. Schwarz; Chem. Abstr. 93, 240249b (1980); H. F. Kuhfuss and W. J. Jackson, Jr., U.S. Pat. No. 3,778,410 (Dec. 11, 1973) to Eastman Kodak: Chem. Abstr. 80, 146894t (1974); H. F. Kuhfuss and W. J. Jackson, Jr., U.S. Pat. No. 3,804,805 (Apr. 16, 1974) to Eastman Kodak: Chem. Abstr. 83, 60301x (1975), ICI Ltd. (Goodman, I., McIntyre, J. E. and Aldred, D. H. ) Bri. Pat. 993272 (priority May 22, 1962), Du Pont (Schaefgen, J. R. et al.) Brit. Pat. 1507207 (priority May 10, 1974, USA); Du Pont (Kleinschuster, J. J.) U.S. Pat. No. 3,991,014 (priority Jul. 16, 1975); A., Blumstein (Ed), Polymeric Liquid Crystals, Plenum Press, New York (1985); C. Noel and P. Navard,
Progr. Polym. Sci.
, 16, 55-110 (1991); Frank, J. Jedlinski and J. Majnus in Hand Book of Polymer Synthesis, H. F. Kricheldorf (Ed), (1991); W. J. Jackson, Jr. and H. F. Kuhfuss,
J. Polym. Sci., Polym. Chem. Ed.
, 14:2043 (1976); W. J. Jackson, Jr.
Macromolecules
, 16:1027 (1983); 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. 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. 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); 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. I. 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. 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
; Handbook of polymer science
, N. P. Cheremisinoff (Ed.), vol. 3, synthesis and characterization of Aromatic polyesters; 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 structure etc. or by copolymerising with suitable comonomers that bring down the transition temperatures. 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. In this situation, 4-hydroxy phenyl acetic acid, and 3(4-hydroxyphenyl propionic acid), the monomers that possesses a CH
2
-unit between the carboxyl and the rigid phenyl unit 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 X7G) has several short comings in that the heat distortion temp is low (<90° C.) and the thermal stability is low because esters of aliphatic diols decompose above 300° C. via cis &bgr; elimination to yield olefins. Besides at mole ratios 4-hydroxybenzoic acid/polyethylene terepthalate of greater than 1.5: 1.0, heterogeneous materials are obtained containing crystallites of nearly pure poly (4-hydroxybenzoates). Recently, one fully aromatic LC copolyester (Vectra®) and terpolyester (Xydar®) of 4-hydroxy benzoic acid were commercialised possessing high heat distortion temperatures and high thermal stabilities. However, due to the high melting points of these polyesters (>300° C.) processing is rather difficult.
The homopolyester of 4-hydroxyphenyl acetic acid and its polyester with 4-hydroxy benzoic acid are melt processable liquid crystalline polymers exhibiting clear nematic phase. The terpolyesters of 4-hydroxyphenyl acetic acid and 3(4-hydroxy phenyl)propionic acid with hydroquinone/4,4′ biphenol/2,6-naphthylene diol and terephthalic acid are expected to be melt processable with lower melt transition temperatures than that of commercial terpolyesters like Xydar®. Although this is the easiest route to achieve melt processability, there is no publication or patent on the preparation of the terpolyester. Though homopolymerisation of 4-hydroxybenzoic acid is well studied, only a few reports are available on the polymerisation and characterisation of 4-hydroxyben
Pillai Chennakkattu Krishna Sadasivan
Prasad Vadakkethonippurathu Sivankutty Nair
Ravindranathan Marayil
Council of Scientific & Industrial Research
Ladas & Parry
Wu Shean C.
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