Aromatic polycarbonate

Details Aromatic polycarbonate Aromatic polycarbonate

1999-11-22

2001-07-03

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

06255436

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an aromatic polycarbonate and in particular, to an aromatic polycarbonate which is improved in color tone and heat resistance.
Polycarbonate resins have been extensively used in various application fields because of excellent impact resistance, transparency or the like. Among others, these polycarbonate resins are especially useful as transparent materials such as optical discs, sheets, molding materials, alternate materials for glass products or the like. However, the polycarbonate resins have to be kneaded and molded at a high temperature of 250 to 380° C. due to a high melting viscosity thereof. Therefore, there arises such a problem that these resins tend to be discolored when kneaded with additives and molded.
In order to solve the above problem, in the case where polycarbonate resins are produced by a so-called interfacial polymerization method of reacting an aromatic dihydroxy compound with phosgene, it has been attempted to improve the heat resistance of these resins by reducing an amount of methylene chloride used as a solvent, an amount of chlorine components derived from phosgene, or the like. On the other hand, in the transesterification method of heat-reacting the aromatic dihydroxy compound with the carbonic acid diester compound under a reduced pressure, it has been attempted to improve properties of the obtained polycarbonate resins by reducing a content of the carbonic acid diester as a raw material, deactivating the catalyst, etc. (Japanese Patent Application Laid-Open (KOKAI) No. 7-126374(1995)). However, these methods have failed to obtain polycarbonate resins having a sufficient thermal stability. Therefore, there has been demanded a further improvement in the production of polycarbonate.
As a result of the present inventors' earnest studies concerning the improvement of color tone, heat resistance and the like of polycarbonate resins for solving the above problems, it has been found that by reducing the content of a cyclic oligomer which is produced under specific conditions upon the production of polycarbonate resins, to not more than a specific value, and reducing the percentage of the cyclic oligomer content based on a total oligomer content, to not more than a specific percentage, the obtained polycarbonate resins can be considerably improved in color tone and heat resistance. The present invention has been attained on the basis of the finding.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a polycarbonate resin which is improved in color tone, heat resistance and the like.
In an aspect of the present invention, there is provided an aromatic polycarbonate which is produced by reacting an aromatic dihydroxy compound with a compound capable of introducing a carbonate bond, and has a viscosity-average molecular weight of 12,000 to 40,000 and a content of a cyclic oligomer represented by the following formula (1) of not more than 1,000 ppm, and
in which the percentage of the content of said cyclic oligomer represented by the formula (1) based on the total contents of said cyclic oligomer represented by the formula (1), an oligomer represented by the following formula (2) and an oligomer represented by the following formula (3) satisfies the following relational formula [I]:
0
<
(
1
)
(
1
)
+
(
2
)
+
(
3
)
×
100
<
3.6
×
10
-
8
×
(
Mv
)
2
[
I
]
wherein (1), (2) and (3) are contents of the oligomers represented by the formulae (1), (2) and (3), respectively; and Mv is a viscosity-average molecular weight of said aromatic polycarbonate.
wherein B is a divalent group selected from the group consisting of a halogen-substituted or unsubstituted C
1
to C
15
hydrocarbon group, O, S, CO, SO and SO
2
; X is a monovalent group selected from the group consisting of a halogen atom, a substituted or unsubstituted C
1
to C
14
aliphatic group, a substituted or unsubstituted C
6
to C
18
aromatic group, a C
1
to C
8
oxyalkyl group and a C
6
to C
18
oxyaryl group; m is an integer of 2 to 8; p is an integer of 0 to 4; s is an integer of 0 or 1; and X's and p's are respectively the same or different.
wherein A and A′ are independently a monovalent group selected from the group consisting of a substituted or unsubstituted C
1
to C
18
aliphatic group and a substituted or unsubstituted C
6
to C
18
aromatic group, and may be the same or different; n is an integer of 1 to 7; and B, X, p and s have the same meanings as set forth in the above formula (1).
wherein A″ is a monovalent group selected from the group consisting of a substituted or unsubstituted C
1
to C
18
aliphatic group and a substituted or unsubstituted C
6
to C
18
aromatic group; n′ is an integer of 1 to 7; and B, X, p and s have the same meanings as set forth in the above formula (1).


REFERENCES:
patent: 4789730 (1988-12-01), Priddy
patent: 0524380 (1993-01-01), None
patent: 0708128 (1996-04-01), None
patent: 0719816 (1996-07-01), None
patent: 0719815 (1996-07-01), None
patent: 62-190222 (1987-08-01), None
patent: 62-190220 (1987-08-01), None
patent: 62-190221 (1987-08-01), None
patent: 002135120 (1995-04-01), None
patent: 7-126374 (1995-05-01), None

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