Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
1999-10-04
2002-06-25
Killos, Paul J. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C558S274000
Reexamination Certificate
active
06410777
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a salicylic acid ester derivative having an impurity concentration not more than a specific level and its production process, more particularly, the present invention relates to a salicylic acid ester derivative having a quality and a reactivity sufficiently high to be usable as a terminal blocking agent or a polymerization promoter in the production process of an aromatic polycarbonate and to its production process.
An aromatic polycarbonate especially useful for optical materials can be produced by the use of the salicylic acid ester derivative disclosed in the present invention. The aromatic polycarbonate produced by using the derivative is preferable especially for optical disks among the optical materials.
BACKGROUND ARTS
Polycarbonates are widely used owing to the excellent mechanical properties such as impact resistance as well as heat-resistance, transparency, etc. Especially, a polycarbonate having bisphenol A (2,2-bis(4-hydroxyphenyl)propane) as a repeating unit is recently increasing its demand mainly in the optical media use such as compact disk and CD-ROM.
The coupling reaction of an aromatic diol such as bisphenol A with phosgene (interfacial polymerization process), the transesterification reaction of an aromatic diol with a diaryl carbonate such as diphenyl carbonate in molten state (melt process), etc., are known as the process for the production of the polycarbonate.
Among the production processes, the melt process is expected to be promising in future compared with interfacial polymerization process because the melt process is free from the problem of the use of toxic phosgene and halogen compounds such as methylene chloride as a solvent to enable the production of polycarbonate at a low cost.
There are several disclosed examples to improve the physical properties of polycarbonate produced by the melt process by controlling the structure of the terminal group of the polymer.
For example, JP-B 7-39483 (hereunder, JP-B means “Japanese Examined Patent Publication”) and JP-A 6-157739 (hereunder, JP-A means “Japanese Unexamined Patent Publication”) describe the blocking of the terminal groups with specific compounds expressed by the following formula (a carbonic acid diester having a carbon number of from 17 to 50)
[R
X
is a hydrocarbon group having a carbon number of from 3 to 36] or the following formula
[R
Y
is a hydrocarbon group having a carbon number of from 1 to 30, and R
Z
is a hydrocarbon group having a carbon number of from 1 to 20]. However, the terminal blocking agents disclosed in the above specifications have defects which its reaction needs long time, etc., and there is no disclosure of the influence of impurity concentration in the blocking agent on the terminal blocking reaction rate and the color of the produced polymer in the case of using the above compound as the terminal blocking agent.
The inventors of the present invention have disclosed in JP-A 10-36497 and U.S. Pat. No. 5,696,222, etc., that a specific carbonic acid diester derivative containing a salicylic acid ester derivative as an eliminable group in the constituent component is effective as a terminal blocking agent in the process for the production of polycarbonate by melt process. However, the influence of impurities in these specific carbonic acid diester derivatives on the polymer and the influence of impurities on the production of the derivative were left unexamined in the above specifications.
A carbonic acid diester compound can be synthesized generally by a known method, as disclosed in JP-A 52-111540 for example, comprising the coupling of a chloroformate expressed by the following general formula
(R is phenyl or benzyl) with an alcohol expressed by the following formula
R—OH
(R is an alkyl) in the presence of a base such as an amine.
Since the raw materials contains large amounts of chlorine and nitrogen, chlorine and nitrogen impurities may be included in the carbonic acid diester synthesized by this process according to the synthetic conditions and purification method.
The use of such carbonic acid diester containing large amount of impurities as the terminal blocking agent of a polycarbonate creates various problems such as the insufficient progress of the reaction and the deterioration of the color of the produced polymer. However, the means for solving these problems are left uninvestigated.
Problems to be Solved by the Invention
The object of the present invention is to produce a polycarbonate having good color and suitable for optical materials, especially for optical disk substrate without lowering the terminal blocking reaction rate or the polymerization promoting reaction rate in the case of using a specific salicylic acid ester derivative as a terminal blocking agent or a polymerization promoter by decreasing the impurity content of the salicylic acid ester derivative effective as a terminal blocking agent or a polymerization promoting agent of polycarbonate to or below a specific level.
Means for Solving the Problems
The present invention discloses a specific salicylic acid ester derivative effective as a terminal blocking agent or a polymerization promoting agent of a polycarbonate and having an impurity concentration decreased to or below a specific level.
Salicylic Acid Ester Derivative
The specific salicylic acid ester derivative compound in the present invention means a compound expressed by the following formula (1)
(wherein R
1
is methyl or ethyl, R
2
is an alkyl group having a carbon number of from 1 to 30, an alkoxy group having a carbon number of from 1 to 30, an aryl group having a carbon number of from 6 to 30, an aryloxy group having a carbon number of from 6 to 30, an aralkyl group having a carbon number of from 6 to 30 or an aralkyloxy group having a carbon number of from 6 to 30. The group R
2
may have, as a substituent, methoxycarbonyl group, ethoxycarbonyl group, 2-(methoxycarbonyl)-phenyloxycarbonyl group, 2-(methoxycarbonyl)phenyloxycarbonyloxy group, 2-(ethoxycarbonyl)phenyloxycarbonyl group, 2-(ethoxycarbonyl)-phenyloxycarbonyloxy group or an aryloxycarbonyl group or an aralkyloxycarbonyl group having a carbon number of from 6 to 10).
The alkyl group having a carbon number of from 1 to 30 may have straight-chain form, branched form or cyclic form and may contain unsaturated group. Examples of such alkyl groups are straight-chain alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-nonyl group, n-lauryl group, n-stearyl group, n-docosanyl group and n-heptacosanyl group, branched-chain alkyl groups such as isopropyl group, t-butyl group, 3-hexyldecanyl group and 6-butyltetracosanyl group, unsaturated alkyl groups such as allyl group, butenyl group, pentenyl group, hexenyl group, dodecenyl group, oleyl group and 6-docosenyl group, cyclic alkyl groups such as cyclohexyl group, 4-nonylcyclohexyl group, 4-pentenylcyclohexyl group and norbornyl group, etc.
The alkoxy groups having a carbon number of from 1 to 30 may have straight-chain form, branched form or cyclic form and may contain unsaturated group. Examples of such alkoxy groups are straight-chain alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, n-hexyloxy group, n-octyloxy group, n-nonyloxy group, n-stearyloxy group, n-docosanyloxy group and n-hexacosanyloxy group, branched-chain alkoxy groups such as isopropyloxy group and 3-hexyldodecanyloxy group, unsaturated alkoxy groups such as allyloxy group, butenyloxy group, pentenyloxy group, hexenyloxy group and dodecenyloxy group, cyclic alkyloxy groups such as cyclohexyloxy group, etc.
The aryl group having a carbon number of from 6 to 30 are, for example, phenyl group, naphthyl group, anthranyl group, biphenyl group and pyrenyl group.
Examples of the aryloxy groups having a carbon number of from 6 to 30 are phenyloxy group, naphthyloxy group, anthranyloxy group, biphenyloxy group and pyrenyloxy group.
The aralkyl groups having a carbon number of from 6 to
Funakoshi Wataru
Kaneko Hiroaki
Sasaki Katsushi
Killos Paul J.
Teijin Limited
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