Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-12-06
2001-08-07
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S147000, C524S151000, C524S156000, C524S157000, C524S158000, C524S317000, C524S414000
Reexamination Certificate
active
06271290
ABSTRACT:
BACKGROUND OF THE INVENTION
The present application is a U.S. non-provisional application based upon and claiming priority from Japanese Application No. HEI 10-348852 is hereby incorporated by reference.
The present invention concerns a polycarbonate resin for optical use, and more specifically concerns a polycarbonate resin for optical use that has excellent color tone stability and forming properties, and is particularly suited for the substrates of optical disks.
Polycarbonate has excellent mechanical properties such as impact resistance, and it also has excellent heat resistance and transparency; therefore, it is widely used for the parts of many kinds of machines and equipment, optical disks, automobile parts, etc. Research has been conducted extensively in great anticipation of its application to optical uses, particularly optical disks for memory storage, optical fibers, lenses, etc.
Well-known methods for manufacturing polycarbonate include a process in which a bisphenol such as bisphenol A is reacted directly with phosgene (interface method) and a process in which a bisphenol such as bisphenol A undergoes a melt polycondensation reaction with a carbonic acid diester such as diphenyl carbonate (ester substitution reaction).
Among these methods, the interface method that uses phosgene requires large quantities of solvent such as methylene chloride, and because the removal of the chlorine is extremely difficult, the polycarbonate produced is not always satisfactory for optical use.
On the other hand, one advantage of the melt polycondensation reaction method is that polycarbonate can be manufactured relatively inexpensively compared with the interface method. Moreover, because it does not utilize toxic substances such as phosphene or large quantities of a solvent such as methyl chloride, it shows great promise as a manufacturing method for polycarbonate for optical use.
However, a polycarbonate resin composition that can be used for optical applications must have excellent color tone stability and not be discolored by heating during the forming process.
The addition of various types of phosphorous acid ester compounds to the polycarbonate has been proposed in JP Kokai 98-60247 and JP Kokai 92-81457 as attempts to improve the color tone stability of polycarbonate during the forming process, but both these procedures concern polycarbonate that is obtained by the interface method that utilizes phosgene, and when these procedures were applied without modification to the melt polycondensation method, sufficient improvement in the color tone stability of the polycarbonate resin could not be obtained.
Therefore, the applicants have discovered that a polycarbonate with improved color tone stability can be obtained by the addition of an acidic compound to the reaction product obtained in a melt polycondensation process, and have proposed this solution in JP Kokai 92-175368, JP Kokai 92-328156, and JP Kokai 93-262969.
However, although these kinds of polycarbonate resins have color tone stability at relatively low temperatures, they are not always satisfactory for applications that require excellent color tone stability and working properties at higher temperatures such as the high density DVD and DVD-R disks that have been developed in recent years, and therefore an improvement was needed.
The inventors considered this problem carefully, and after diligent research discovered that a polycarbonate resin composition with excellent color tone stability at high temperatures can be obtained by the further addition of a specified amount of acidic compound when various types of lubricants are blended into the polycarbonate, thus completing the present invention.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a manufacturing method for a polycarbonate for optical use that has excellent color tone stability and working properties at high temperatures.
The polycarbonate resin composition for optical use in the present invention comprises (A) polycarbonate, (B) phosphorous acid, (C) a sulfur-containing acidic compound or its derivative with a pKa of less than 3, and (D) an ester derived from a mono-fatty acid of 10 to 22 carbon atoms and a polyhydric alcohol.
DETAILED DESCRIPTION OF THE INVENTION
The polycarbonate resin for optical use comprises:
(A) a polycarbonate obtained by the addition of 0.1 to 4.5 ppm of a sulfur-containing acidic compound, or its derivative having a pKa of less than 3, to the reaction product obtained by melt polycondensation of bisphenol and a carbonic acid diester in the presence of an alkaline catalyst. After preparation, the following further ingredients are blended together with the reaction product:
(B) Phosphorous acid,
(C) A sulfur-containing acidic compound or its derivative having a pKa of less than 3, and
(D) An ester derived from a mono-fatty acid of 10 to 22 carbon atoms and a polyhydric alcohol.
The proportions of ingredients are as follows. With respect to the polycarbonate constituent (A), the content of the phosphorous acid constituent (B) is 0.1 to 10 ppm, the content of the acidic compound constituent (C) is 0.1 to 3 ppm,
and the content of the ester constituent (D) is 50 to 1000 ppm.
The polycarbonate resin composition for optical use preferably contains 10 to 1000 ppm of constituent (E), at least one type of compound selected from a group consisting of phosphorous acid ester and trimethyl phosphate.
The polycarbonate resin composition for optical use preferably contains 50 to 500 ppm of constituent (F), an ester derived from a mono-fatty acid of 8 to 22 carbon atoms and polyethylene glycol.
The polycarbonate resin composition in the present invention is explained below in specific terms.
Constituent A: Polycarbonate
The polycarbonate used in the present invention is obtained by the addition of 0.1 to 4.5 ppm of a sulfur-containing acidic compound or its derivative with a pKa of less than 3 to the reaction product obtained by the polycondensation of a bisphenol and a carbonic acid diester in the presence of an alkaline catalyst.
No particular restriction is placed on the bisphenol, and it is represented, for example, by Formula [I] below.
(Wherein, R
a
and R
b
represent the same or different halogen atoms or single-bonded hydrocarbon groups. Items p and q are integers from 0 to 4. X represents the group
in which R
c
and R
d
are hydrogen atoms or single-bonded hydrocarbon groups, R
c
and R
d
may have a cyclic structure, and R
e
is a double-bonded hydrocarbon group.)
For the bisphenol shown in Formula [I], specific examples include bis (hydroxyaryl) alkanes such as 1,1-bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A), 2,2-bis (4hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, 1,1-bis (4hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) N-butane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-1-methylphenyl) propane, 1,1-bis (4-hydroxy-t-butylphenyl) propane, 2,2-bis (4hydroxy-3-bromophenyl) propane, etc., and bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, etc.
In the present invention, bisphenols in which X in the above formula represents —O—, —S, —SO— or —SO
2
include, for example, bis (hydroxy diaryl) ethers such as 4,4′-dihydroxy diphenyl ether, 4,4′-dihydroxy-3,3′-dimethyl diphenyl ether, etc., bis (hydroxy diaryl) sulfides such as 4,4′-dihydroxy diphenyl sulfide, 4,4′-dihydroxy-3,3′-dimethyl diphenyl sulfide, etc., bis (hydroxy diaryl) sulfoxides such as 4,4′-dihydroxy diphenyl sulfoxide, 4,4′-dihydroxy-3,3′-dimethyl diphenyl sulfoxide, etc., and bis (hydroxy diaryl) sulfones such as 4,4′-dihydroxy diphenyl sulfone, 4,4′-dihydroxy-3,3′-dimethyl diphenyl sulfone, etc.
Moreover, the types of bisphenols shown in Formula [II] below may also be used.
(wherein, R
f
is a halogen atom, or a hydrocarbon or halogen-substituted hydrocarbon group of 1 t
Hoeks Theodorus Lambertus
Inoue Kazushige
Ishida Hiromi
Markestein Lennard Alexander
Buttner David J.
General Electric Company
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