Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2001-08-27
2003-01-28
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S176000, C528S190000, C528S193000, C528S271000
Reexamination Certificate
active
06512079
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a liquid crystalline polyester and a method of producing the same.
BACKGROUND OF THE INVENTION
Liquid crystalline polyesters having an aromatic ring skeleton are used recently in electric and electronic fields as materials excellent in heat resistance and tensile strength. Liquid crystalline polyesters are produced, for example, by a method of adding acetic anhydride to phenolic hydroxyl groups of an aromatic hydroxycarboxylic acid such as p-hydroxybenzoic acid and the like and/or an aromatic diol such as 4,4′-dihydroxybiphenyl and the like for acylation of the phenolic hydroxyl groups to give an acylated substance and trans-esterifying the acylated substance with an aromatic dicarboxylic acid such as terephthalic acid and the like, and other methods.
However, in this method, time required for acylation is long, leading to a problem in productivity, and there is further a problem that a liquid crystalline polyester having an aromatic skeleton obtained by this method has not necessarily sufficient impact strength though it has excellent heat resistance and tensile strength.
For solving such problems, there is known a method in which an organometal compound such as sodium acetate and the like is added as a catalyst in an acylation reaction to decrease the reaction time (JP-A No. 11-246654). However, this method has a problem that a metal ion remains in a resin, leading to poor insulation ability, and there is further a problem that a liquid crystalline polyester having an aromatic skeleton obtained by this method has not necessarily sufficient impact strength.
Further, there is also known a method in which an organic compound having low boiling point such as pyridine and the like is added as a catalyst in an acylation reaction to decrease the reaction time (JP-A No. 6-1836). However, this method has problems that time for trans-esterification is delayed and coloration owing to a side-reaction occurs and there is further a problem that a liquid crystalline polyester having an aromatic skeleton obtained by this method has not necessarily sufficient impact strength.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a liquid crystalline polyester manifesting excellent impact strength without deteriorating excellent heat resistance and tensile strength, and a method for producing a liquid crystalline polyester having excellent productivity and causing no coloration.
The present inventors have intensively studied a liquid crystalline polyester which does not have the above-described problems, and resultantly found that a liquid crystalline polyester obtained by conducting acylation, trans-esterification, or the acylation and trans-esterification in the presence of a heterocyclic organic base compound containing two or more nitrogen atoms, manifests excellent impact strength while maintaining excellent heat resistance and tensile strength, and also that a liquid crystalline polyester can be produced efficiently without causing coloration due to a side reaction by conducting acylation, trans-esterification, or acylation and trans-esterification in the presence of a heterocyclic organic base compound containing two or more nitrogen atoms, and have completed the present invention.
Namely, the present invention provides
[1] a method for producing a liquid crystalline polyester comprising the steps of
acylating phenolic hydroxyl groups of an aromatic diol, an aromatic hydroxycarboxylic acid, or an aromatic diol and aromatic hydroxycarboxylic acid with a fatty anhydride to obtain an acylated substance, and
trans-esterifying said acylated substance with an aromatic dicarboxylic acid, an aromatic hydroxycarboxylic acid, or an aromatic dicarboxylic acid and aromatic hydroxycarboxylic acid,
wherein the acylation, the trans-esterification, or the acylation and trans-esterification is conducted in the presence of a heterocyclic organic base compound containing two or more nitrogen atoms, and
[2] a liquid crystalline polyester obtained by the method [1].
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The liquid crystalline polyester of the present invention has an aromatic ring skeleton which forms a melted phase having optical anisotropy, is excellent in heat resistance and tensile strength, further, excellent also in impact strength.
The liquid crystalline polyester of the present invention can be obtained by polycondensation by trans-esterifying an aromatic dicarboxylic acid and/or an aromatic hydroxycarboxylic acid with an acylated substance obtained by acylating phenolic hydroxyl groups of an aromatic diol and/or an aromatic hydroxycarboxylic acid with a fatty anhydride, and is characterized in that it is obtained by conducting acylation, trans-esterification, or acylation and trans-esterification in the presence of a heterocyclic organic base compound containing two or more nitrogen atoms.
First, a process in which phenolic hydroxyl groups of an aromatic diol and/or an aromatic hydroxycarboxylic acid are acylated with a fatty anhydride will be described.
Examples of the aromatic diol include 4,4′-dihydroxybiphenyl (hereinafter, abbreviated as (C1) in some cases), hydroquinone (hereinafter, abbreviated as (C2) in some cases), resorcin (hereinafter, abbreviated as (C3) in some cases), methylhydroquinone, chlorohydroquinone, acetoxyhydroquinone, nitrohydroquinone, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene (hereinafter, abbreviated as (C4) in some cases), 2,7-dihydroxynaphthalene, 2,2-bis(4-hydroxyphenyl)propane (hereinafter, abbreviated as (C5) in some cases), 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, bis-(4-hydroxyphenyl)methane, bis-(4-hydroxy-3,5-dimethylphenyl)methane, bis-(4-hydroxy-3,5-dichlorophenyl)methane, bis-(4-hydroxy-3,5-dibromophenyl)methane, bis-(4-hydroxy-3-methylphenyl)methane, bis-(4-hydroxy-3-chlorophenyl)methane, 1,1-bis(4-hydroxyphenyl)cyclohexane,bis-(4-hydroxyphenyl) ketone,bis-(4-hydroxy-3,5-dimethylphenyl)ketone, bis-(4-hydroxy-3,5-dichlorophenyl)ketone, bis-(4-hydroxyphenyl)sulfide,bis-(4-hydroxyphenyl) sulfone (hereinafter, abbreviated as (C6) in some cases) and the like. These may be used singly or in combination of two or more.
Among them, 4,4′-dihydroxybiphenyl, hydroquinone, resorcin, 2,6-dihydroxynaphthalene, 2,2-bis(4-hydroxyphenyl)propane and bis-(4-hydroxyphenyl) sulfone are preferably used because of easy availability.
Examples of the aromatic hydroxycarboxylic acid include p-hydroxybenzoic acid (hereinafter, abbreviated as (A1) in some cases), m-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid (hereinafter, abbreviated as (A2) in some cases), 2-hydroxy-3-naphthoic acid,1-hydroxy-4-naphthoic acid, 4-hydroxy-4′-carboxydiphenyl ether, 2,6-dichloro-p-hydroxybenzoic acid, 2-chloro-p-hydroxybenzoic acid, 2,6-difluoro-p-hydroxybenzoic acid, 4-hydroxy-4′-biphenylcarboxylic acid and the like. These may be used alone or in combination of two or more. Of them, p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid are preferably used because of easy availability.
Examples of the fatty anhydride include, but are not limited to, acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, pivalic anhydride, 2-ethylhexanoic anhydride, monochloroacetic anhydride, dichloroacetic anhydride, trichloroacetic anhydride, monobromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, &bgr;-bromopropionic anhydride, and the like. These may be used in admixture of two or more. Acetic anhydride, propionic anhydride, butyric anhydride and isobutyric anhydride are preferably used from the standpoint of cost and handling property, and acetic anhydride is more preferabl
Hirakawa Manabu
Okamoto Satoshi
Birch & Stewart Kolasch & Birch, LLP
Boykin Terressa M.
Sumitomo Chemical Company Limited
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