Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-01-21
2001-10-09
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S198000
Reexamination Certificate
active
06300459
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for the production of an aromatic polycarbonate having high molecular weight, more particularly, to a process for the production of an aromatic polycarbonate having high molecular weight, by increasing the terminal hydroxyl group content of an aromatic polycarbonate followed by application of a salicylic acid ester derivative having a specific structure as a condensation agent. The present invention is effectively utilizable especially for the recycling of an aromatic polycarbonate.
BACKGROUND TECHNOLOGY
Polycarbonate is widely used owing to its excellent mechanical characteristics such as impact resistance as well as high heat-resistance, transparency, etc. Aromatic polycarbonate has recently been used for recording materials such as optical disks and the demand has been increasing sharply.
Known methods for the production of such polycarbonate include the direct reaction of an aromatic diol such as bisphenol A with phosgene (the interfacial polymerization method) and the transesterification reaction of an aromatic diol with a diaryl carbonate such as diphenyl carbonate (the melt method).
Regarding polycarbonate produced by the above methods, U.S. Pat. No. 5,521,275 discloses a process for converting the molecular weight of an aromatic polycarbonate in the presence of a catalyst using an extruder with a polymer seal section and a venting section under a reduced pressure, and European Patent No. 0,595,608 discloses a process for reacting several kinds of diaryl carbonates in the conversion of the molecular weight. However, the processes disclosed in these patent specifications cannot significantly increase the molecular weight of polycarbonate.
DISCLOSURE OF INVENTION
The present invention have been accomplished by the finding of the inventors that the molecular weight of a polymer is remarkably increased by controlling the number of hydroxyl terminals in the polymer and using a specific salicylic acid compound.
The present invention comprises a process to produce an aromatic polycarbonate having a high molecular weight by treating, in the presence of a transesterification catalyst, an aromatic polycarbonate with an active-hydrogen compound to perform transesterification reaction under a reduced pressure and using a salicylic acid ester derivative having a specific structure as a condensation agent.
This process enables conversion to a polymer having a high molecular weight after remelting, of an aromatic polycarbonate which has been once polymerized and molded into a shaped article. Thus a reclaimed polycarbonate obtained from recovered molded disks, etc. can be recycled to a polycarbonate having high molecular weight. Since the present invention allows for a shortened time necessary for increasing the molecular weight, a polymer having excellent hue can be obtained by this process.
The polycarbonate disclosed in the present invention can be favorably used for applications such as various molded articles, sheets and films, produced by injection molding, blow molding, extrusion molding, injection blow molding, rotational molding, compression molding, etc. When employed in these applications, a polycarbonate obtained by the present invention can be used either singly or as a blend with other polymers. In some applications, various types of processing such as hard coating or lamination may be favorably used.
Examples of the molded articles include optical media such as a compact disk, a digital video disk, a mini-disk and a magneto-optical disk, optical communication media such as an optical fiber, optical parts such as a head lamp lens of an automobile and a lens of a camera, optical instrument parts such as a cover of a siren and light system and an illumination lamp cover, alternatives to window glass panes for vehicles such as an electric car and an automobile, alternatives to home window glass panes, daylighting parts such as a sunroof and a roof of a greenhouse, lenses and casings of goggles, sunglasses and eyeglasses, casings of OA instruments such as a copying machine, a facsimile machine and a personal computer, casings of domestic appliances such as a television set and a microwave oven, electronic parts such as a connector and an IC tray, protection tools such as a helmet, a protector and a protective faceshield, tableware such as a tray, and medical instruments such as an artificial dialysis casing and an artificial denture. The present invention, however, is by no means restricted by the above examples.
The inventors of the present invention have found that an aromatic polycarbonate having a high molecular weight can be produced by treating an aromatic polycarbonate with an active-hydrogen compound in the presence of a transesterification catalyst, to perform transesterification reaction under a reduced pressure followed by reaction with a salicylic acid ester derivative expressed by the following formula (1)
{wherein X is a methyl group or an ethyl group and Y is a carbonyl group or a divalent functional group expressed by the following formula (2),
(where Z is an alkylene group having a carbon number of 1 to 30, an arylene group having a carbon number of 6 to 30 or an aralkylene group having a carbon number of 7 to 30)}. In the present invention, the aromatic polycarbonate prior to the reaction refers to a polymer expressed by the following formula (3)
In the formula, the groups R
1
and R
2
are, each same or different, a hydrogen atom, a halogen atom or a hydrocarbon group having a carbon number of 1 to 12. The hydrocarbon group is preferably an aliphatic hydrocarbon group having a carbon number of 1 to 12 or an aromatic hydrocarbon group having a carbon number of 6 to 12. The halogen atom is preferably chlorine, bromine, iodine, etc.
In the formula, m and n are, each same or different, a number selected from 0 and integers from 1 to 4.
For the A in the above formula (3), the groups R
3
and R
4
are, same or different, a halogen atom or a monovalent hydrocarbon group having a carbon number of 1 to 12. As the hydrocarbon group enumerated are aliphatic hydrocarbon groups having a carbon number of 1 to 12 and aromatic hydrocarbon groups having a carbon number of from 6 to 12. Examples of the halogen atom are chlorine, bromine and iodine.
The group R
5
is an alkylene group having a carbon number of 3 to 8, such as pentylene group or hexylene group.
A polymer prior to the reaction in the present invention may be synthesized by the interfacial polymerization method, melt method, solid-phase polymerization method or thin-film polymerization method. A reclaimed polymer can also be used as the polymer prior to the reaction provided that the polymer falls within the scope of the present invention. These polycarbonates may be mixed with each other for use as the polymer prior to the reaction. For example, a polymer polymerized by the interfacial method may be mixed with a polymer polymerized by the melt method, or a polymer polymerized by the melt method may be mixed with a polymer obtained through recovery of molded disks.
The intrinsic viscosity (&eegr;) of the polycarbonate is preferably in the range of 0.2 to 0.6, more preferably 0.25 to 0.50. The intrinsic viscosity (&eegr;) of the polymer can be determined by measuring the viscosity in methylene chloride at 20° C. using a Ubbellohde viscometer.
The aromatic polycarbonate used in the present invention refers to a polycondensate having a reaction product of an aromatic dihydroxy compound with a carbonate-bond forming compound as the main recurring unit. The aromatic dihydroxy compound is preferably a compound expressed by the following general formula (4)
(wherein R′
1
, R′
2
, R′
3
and R′
4
are each a hydrogen atom, or an alkyl group, an aralkyl group or an aryl group each having a carbon number of 1 to 10; and W is an alkylidene group, an alkylene group, a cycloalkylidene group, a cycloalkylene group or a phenyl-substituted alkylene group having a carbon number of 1 to 30, oxygen atom, sulfur atom, sulfoxide group, s
Funakoshi Wataru
Kaneko Hiroaki
Sasaki Katsushi
Boykin Terressa M.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Teijin Limited
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