Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-12-19
2002-07-09
Killos, Paul J. (Department: 1623)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C528S173000, C528S179000
Reexamination Certificate
active
06417291
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing a polyarylate. More specifically, the present invention relates to a process for producing a polyarylate of high-molecular weight having excellent color tone and hue stability by modifying a part or the whole part of the terminal carboxylic groups and the terminal hydroxyl groups existing at terminals of polymer chains with a specific salicylic acid ester compound.
A polyarylate is one of the engineering plastics, and it is used in various fields recently due to that it is excellent in mechanical properties and moldability, and further in properties such as chemical resistance, impact resistance and electric properties.
As processes for producing such polyarylates, many processes including an interfacial (solution) method in which a halide of an aromatic dicarboxylic acid is made to react with an aromatic dihydroxy compound in the presence of a basic compound, a method (melt-polycondensation method) in which a diaryl ester of an aromatic dicarboxylic acid and an aromatic dihydroxy compound are polymerized with each other by removing a phenolic compound (aromatic monohydroxy compound) and a method (melt-polycondensation method) in which a polymer is formed from a molten mixture of an aromatic dicarboxylic acid, an aromatic dihydroxy compound and a diaryl carbonate by removing a phenolic compound (aromatic monohydroxy compound) are known.
Among them, the method (melt-polycondensation method) in which a polymer is formed from a molten mixture of an aromatic dicarboxylic acid, an aromatic dihydroxy compound and a diaryl carbonate by removing a phenolic compound has the possibility of less expensive production since it needs to use no solvent, and a diphenyl carbonate which is a raw material for aromatic polycarbonate production or the like can be used as the diaryl carbonate of the raw material of this method, and thus the method is considered to be promising in future.
BACKGROUND ART
However, a polyarylate polymerization through a melt-polycondensation method has commonly a trouble that the melt viscosity of a polymer characteristically becomes extremely higher than that of another polycondensation polymer, for example, such as polyethylene terephthalate or aromatic polycarbonate with increasing of a polymerization degree, and thereby it is necessary to carry out a special operation, for example, polymerization with an elevated temperature (by reducing viscosity), and as a result, coloring of the polymer occurs.
It has been known that on the coloring during molten state, terminal groups of a polymer has a strong influence. For example, JP-A 4-288324 (JP-A, means Japanese unexamined patent application) has described that coloring is prevented by reducing the amount of phenolic terminal groups of a polyarylate. JP-A 4-222821 discloses a process for producing a polycarbonate useful for molding, by decreasing the concentrations of terminal carboxyl groups and phenolic terminal hydroxyl groups. Further, JP-A 3-64317 discloses a method for controlling the terminal groups by controlling mole balances of raw materials during melt polycondensation.
Also regarding methods using a specific compound as a terminal blocking agent, some investigations have been carried out. For example, JP-A 2-238020 has described a method for reducing the amount of terminal carboxylic acid groups by using an agent selected from the group consisting of diphenyl carbonate, unsubstituted polyaryl carbonate oligomers, unsubstituted polyaryl carbonate polymers, substituted polyaryl carbonate oligomers and substituted polyaryl carbonate polymers. JP-B 6-99548 (JP-B means Japanese examined patent application) discloses a process for producing a polyarylate whose terminal group has been converted to a benzoate group using phenyl benzoate.
Further, JP-A 10-36497 discloses a process for producing a polycarbonate having excellent hue and an increased polymerization degree by using a specific salicylic acid ester derivative when a polycarbonate is produced by a molten method.
However, presently, a truly useful method for preventing coloring has not been proposed yet for polyarylates.
The object of the present invention is to obtain a polyarylate having excellent color tone and hue stability in a process for producing a polycarbonate through the polycondensation of an aromatic dihydroxy compound and an aromatic ester bond forming precursor.
According to the present invention, a modified polyarylate of high-molecular weight, having excellent color tone and hue stability can be produced by modifying a part or the whole part of the terminal carboxylic groups and/or hydroxy groups quickly and sufficiently with a terminal modifying agent by melt polycondensation.
Further, needless to say, in the present invention, “a process for producing a polyarylate through the polycondensation of an aromatic dihydroxy compound and an aromatic ester bond forming precursor” includes the above-mentioned methods, that is, the method (melt-polycondensation method) in which a diaryl ester of an aromatic dicarboxylic acid and an aromatic dihydroxy compound are polymerized with each other by removing a phenolic compound (aromatic monohydroxy compound) and the method (melt-polycondensation method) in which a polymer is formed from a molten mixture of an aromatic dicarboxylic acid, an aromatic dihydroxy compound and a diaryl carbonate by removing a phenolic compound (aromatic monohydroxy compound).
DISCLOSURE OF THE INVENTION
The inventors of the present invention found that hue stability during molten state is improved by blocking polymer terminal groups such as carboxyl groups and hydroxyl groups, which affect strong influences on coloring during molten state, using a salicylic acid ester compound having a specific structure as a terminal modifying agent in a process for producing a polyarylate through the polycondensation of an aromatic dihydroxy compound and an aromatic ester bond forming precursor, and further, that a polyarylate having a high polymerization degree and at the same time excellent in color tone can be obtained by allowing polymer terminal groups to couple to each other through a specific structural part of the salicylic acid ester compound to convert the polymer to the one having higher degree of polymerization in a short time. In addition, in the latter case, the polyarylate has a reduced amount of the polymer terminal groups such as carboxyl groups and hydroxyl groups, which affect strong influences on coloring during molten state, owing to the coupling, and also has an improved hue stability during molten state.
That is, the present invention comprises the following.
1. A process for producing a polyarylate through the polycondensation of an aromatic dihydroxy compound and an aromatic ester bond forming precursor, characterized in that terminal modification reaction is carried out by using a salicylic acid ester compound expressed by the following formula (1) as a terminal modifying agent,
[wherein R
a
is ethyl or methyl; R
b
is a C
1 to 30
alkyl group (hereinafter, C
x to y
means x to y of carbon number), a C
1 to 30
alkoxy group, a C
6 to 30
aryl group or a C
6 to 30
aryloxy group; R
b
is optionally substituted with methoxycarbonyl, ethoxycarbonyl, 2-(methoxycarbonyl)phenyloxycarbonyl, 2-(methoxycarbonyl)phenyloxycarbonyloxy, 2-(ethoxycarbonyl)phenyloxycarbonyl, 2-(ethoxycarbonyl)phenyloxycarbonyloxy, a C
1 to 30
alkyl group, a C
6 to 30
aryl group or a C
6 to 30
aralkyl group].
2. A process for producing a polyarylate described in the description 1, characterized in that a catalyst is used in the polycondensation and/or the terminal modification reaction, and the catalyst is at least one compound selected from the group consisting of all combinations of alkali metal compounds, nitrogen-containing basic compounds, and compounds of a metal element of the group 3, 14 or 15 of the periodic table.
3. A process for producing a polyarylate described in the description 2, characterized in that the nitrogen-containing basic compound includ
Funakoshi Wataru
Kageyama Yuichi
Kaneko Hiroaki
Sasaki Katsushi
Killos Paul J.
Oh Taylor V.
Sughrue & Mion, PLLC
Teijin Limited
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