Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-05-17
2002-07-16
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S179000, C528S180000, C528S190000, C528S191000
Reexamination Certificate
active
06420511
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the preparation of aromatic polyesters (polyarylates) based on polar group substituted aromatic dicarboxylic acids which are used for preparing membranes having improved gas permeation properties.
This is the continuation-in-part of our U.S. patent application Ser. No. 09/181,900 filed on Oct. 29, 1998.
1. Background
Polyesters are high performance engineering plastics with good combination of thermal, mechanical and gas permeation properties. Aromatic polyesters are engineering thermoplastics prepared from aromatic diols and aromatic dicarboxylic acids. Polyarylates based on polar group substituted bisphenols have been widely investigated. However, polyarylates with polar group substituted acid moieties have been paid less attention. One of the advantage of introducing polar groups in the polymer backbone is that it increases solubility in common solvents.
Aromatic polyesters based on polar group (such as halogen atoms, nitro group, sulfo group or a similar polar group or combination of these polar groups) substituted acid can have wide range of applications. One application is their use as membrane materials for the separation of mixture of gases or liquids. Membranes made of these polyarylates have generally superior permeation properties for separations such as hydrogen from methane, helium from nitrogen, or oxygen from nitrogen.
2. Prior Art
In the prior art, aromatic polyester (polyarylates) are prepared either by one phase (solution or melt) or two phase (interfacial) polycondensation methods [G. Allen et al, eds. Comprehensive Polymer Science, 1st ed, Pergaman press, Oxford, (1989); P. W. Morgan, Condensation Polymers by Interscience, NY (1965)]. P. K. Bhowmik et al (Macromolecules 26, 5287-5287-5294, 1993) have synthesized polyarylates based on bromoterephthalic acid and biphenyls or binaphthyls in 90-95% yields and moderate intrinsic viscosities by melt condensation method. Polyarylates based on bisphenol-A, hexaflurobisphenol-A, 9,9-bis(4-hydroxy phenyl) fluorene and 3-(4-hydroxyphenyl)-1,1,3-trimethyl-5-indanol have been synthesized with tetrafluoro isophthalic acid (M. Kakimoto et al,
J. Polym. Sci.: Part A: Polym. Chem.,
25, 2747-2753, 1987) and with tetrafluoroterephthalic acid (Y. Oishi et al,
J. Polym. Sci.: Part A: Polym. Chem.,
27, 1425-1428, 1989) by interfacial and solution polymerization in good yields.
In the prior art, efforts to incorporate polar groups in the polymer have been reported in the literature for various types of polymers as typified in the following examples: Kawakami et al (Eur. Pat. Appln EP 444, 690,04 September 1991, CA: 115-257902) showed that the polyarylate based on tetrabromobisphenl-A and iso/terephthalic acid had a good oxygen selectivity over nitrogen. In an another report (Kawakami et al Eur. Pat. appln. EP 376, 234, on July 1990; CV: 114-63781) the use of tetrabromobisphenol-A and tetrachlorohexafluorobisphenol-A for making polyarylates with isophthalic acid is taught. Structural variations in other types of polymers are also reported in the literature. U.S. Pat. No. 4,840,686 (J. N. Anand et al, dated Jun. 20, 1989, CA: 112-9941) teaches the use of polycarbonate made from tetrabromobisphenol-A and iso/terephthalic acid (l/l) had permselectivity of O
2
over N
2
of 8.0 with O
2
permeability of 1.4 barrers. In an another report (Kawakami et al
Eur. Pat. appl. EP
376, 234, Jul. 4, 1990, CA: 114-63781) use of tetrabromohexafluorobisphenol-A (TBrHFbisA) and tetrachlorohexafluorobisphenol-A (TClHFbisA) for making polyarylates with isophthalic acid is taught. The polyarylate TBrHFbisA-1 had O
2
/N
2
selectivity of 6.7 with O
2
permeability of 5.25 barrers; while the polyarylate based on TClHFbisA-1 had O
2
/N
2
selectivity of 6.1 with O
2
permeability of 5.64 barrers. Polar group substituted bisphenols are also reported in other types of polymers. U.S. Pat. No. 4,840,686 (J. N. Anand et al, dated Jun. 20, 1989, CA: 112-9441) teaches the use of polycarbonate made from tetrabromobisphenol-A and phosgene. This polymer gave O
2
/N
2
selectivity of 7.4.
Gas permeation properties of polyarylates prepared from isophthalic and terephthalic acid or the mixture of the above acids with various substituted bisphenols have been reported in the literature. Gas permeation properties of polyarylates based on isophthalic acid or t-butyl-isophthalic acid and various substituted bisphenols have been studied (M. R. Pixton and D. R. Paul,
Macromolecules,
28 (1995) pp 8277-8286). The effect of halogenation of bisphenol and phenolphthalein on the gas permeation properties of iso/terephthalic acid based polyarylates has been reported (R. T. Chern and C. N. Provan,
J. Membr. Sci.,
59, (1991) pp 293-304). The effect of bisphenol bridge substitution on the gas permeation properties of resulting iso/terephthalates has also been reported. (A. Y. Houde et al,
J. Membr. Sci.,
103, (1995) pp 167-174) The effect of bisphenol ring substitution on the gas permeation properties of iso/terephthalates has been studied (U. K. Kharul and S. S. Kulkarni,
Polymer,
submitted).
None of the previous efforts have examined the effect of polar group substitutions on the acid moiety in polyarylates as a method of obtaining polymers with attractive gas permeation characteristics.
Preparation of aromatic polyesters based on polar group substituted aromatic dicarboxylic acid
A very few reports are found in the literature in which the nitro or bromo substituted 1,3- or 1,4-benzene dicarboxylic acid (iso or terephthalic acid) have been used for the preparation of polyesters. Preparation of liquid crystalline polyarylates based on various hydroquinones (Hq, methoxy-HQ, t-butyl-Hq, Hq-sulfonic acid) with bromo or nitro substituted terephthalic acids have been reported (Makromol. Chem. 191, 1990, pp 225-235; Macromolecules, 25, 1992, p 7107-7113). A liquid crystalline copolymer based on Br-TPA and TPA with 1, 2-benzene diol and 1,4-benzene diol has been reported (JP 07,233,249; Sep. 5, 1995; CA: 124:57077). The synthesis of polymers based on bisphenol-A with nitro-isophthalic acid or nitro-terephthalic acid have been cited in the literature (Polymer International, 29, 1992, pp 61-68; Alexandria J. Pharm. Sci. 5, 1991, pp 78-82). No transport properties for any of these polymers have been measured. None of the previous efforts have examined the effect of polar group substitutions on the acid moiety in polyarylates as a method of obtaining polymers with attractive gas permeation characteristics. In other words, no report were found on polymers prepared from polar group substituted acids with various substituted bisphenols (i.e., bisphenols having different bridge/ring substitution, substituted bisphenols containing cardo groups, bisphenols based on fluorenone).
OBJECTS OF THE INVENTION
To overcome the drawbacks associated with the prior art process, the present invention provides an improved process for the preparation of aromatic polyesters by polymerization of the bisphenol along with a suitable additive in order to obtain aromatic polyesters having high intrinsic viscosity.
Another object of present invention is to provide an improved process for the preparation of aromatic polyesters based on tetra-substituted bisphenol and polar group substituted aromatic dicarboxylic acid having high viscosity and yield.
In a further object of the present invention is to prepare aromatic polyesters (polyarylates) based on a polar group substituted aromatic dicarboxylic acids with substituted bisphenols having high gas permeability as well as selectivity.
Another object of the invention is to prepare such type of polyarylates to achieve high solubility of these polyarylates in common solvents.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a novel process for the preparation of a polyarylates (aromatic polyesters) with high gas permeability as well as selectivity based on polar groups substituted aromatic dicarboxylic acids with substituted disphenols.
The said process for the preparation
Kharul Ulhas K.
Kulkarni Sudhir S.
Acquah Samuel A.
Council of Scientific and Industrial Research
Ladas & Parry
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