Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-04-30
2002-01-22
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
06340738
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 10-374458, which is hereby incorporated by reference.
The present invention relates to a continuous polycarbonate manufacturing method in which a polycarbonate with few admixtures is manufactured continuously, stably, and efficiently.
Polycarbonates have excellent mechanical properties such as impact resistance, as well as excellent heat resistance, transparency and other properties. They are widely used in applications such as various types of mechanical components, optical disks, and automotive parts. They are particularly promising for optical applications such as miemory-use optical disks, optical fibers, and lenses.
Known methods for manufacturing these polycarbonates include a method in which a bisphenol such as bisphenol A is allowed to react directly with phosgene (interfacial method), and a method in which a bisphenol such as bisphenol A is subjected to a melt polyconciensation reaction (transesterification reaction) with a carbonic faiester s uch as diphenyl carbonate.
Of these two, the interfacial method using, phosgene is the more commonly implemented. On tLhe other hand, an advantage of the transesterification method is that a polycarbonate can be manulfactured more inexpensively than with the interfacial method, and because transesterification does not invole the use of a toxic substance such as phosgene, it is very promising as a polycarbonate manufacturing method.
Still, if the manufacture of a polycarbonate is carried out continuously over an extended period by this transesterification method, white foreign material can become admixed in the manufactured polycarbonate and can clog the piping lines, thereby lowering the manufacturing efficiency.
As a result of diligent research conducted in light of these problems, the inventors discovered that the lower polycarbonate polycondensate produced in the intermediate stage of a polycondensation reaction can crystallize when heated and become a source of white foreign material, and can crystallize on the pipe surfaces and become a cause of pipe clogging.
Upon further research, the inventors arrived at the present invention upon discovering that a lower polycarbonate polycondensate having an intrinsic viscosity between 0.1 and 0.4 dL/g readily undergoes crystallization at temperatures below 230° C., and therefore found that if the polycondensation of a polycarbonate is carried out by setting the temperature to be at least 230° C. on the surface of the reaction ecluipmnent in direct contact with a lower polycarbonate polycondensate having an intrinsic viscosity between 0.1 and 0.4 dL/g, then the admixture of white foreign material and the clogging of the piping due to polycarbonate crystallization will be suppressed, and a polycarbonate with excellent hue stability will be obtained efficiently.
BRIEF SUMMARY OF THE INVENTION
The present invention was conceived on the basis of the above-mentioned problems, and provides a method with wvlich a polycarbonate can be manufactured efficiently without any pipe clogging or foreign material admixture in the course of the continuous manufacture of a polycarbonate.
The continuous method for manufacturing a polycarbonate pertaining to the present invention is characterized in that, in the continuous manufacture of a polycarbonate by transesterification from a dihydroxy compound and a carbonic diester, the crystallization of a polycarbonate lower polycondensate produced in the intermediate stage of a polycondensation reaction whose intrinsic viscosity (IV) measured at 20° C. in metlhylene chloride is between 0.1 and 0.4 dL/g is suppressed by setting the temperature to be at least 230°C. on the surface of the reactor equipment in contact with the polycarbonate lower polycondensate.
DETAILED DESCRIPTION OF THE INVENTION
The continuous method for manufacturing a polycarbonate pertaining to the present invention will now be described in specific terms.
The continuous method for manufacturing a polycarbonate pertaining to the present invention is characterized in that the crystallization of a polycarbonate lower polycondensate produced in the intermediate stage of a polycondensation reaction whose intrinsic viscosity (IV) measured at 20° C. in methylene chloride is between 0.1 and 0.4 dL/g is suppressed by setting the temperature to be at least 230° C. on the surface of the reactor equipment in contact with the polycarbonate lower polycondensate.
First, the raw materials used in the manufacture of a polycarbonate by transesterification will be described.
Polycarbonate Polycondensation Raw Materials
The raw materials used in the polycarbonate manufacturing method pertaining to the present invention are a bisphenol, a carbonic diester, and an alkaline compound catalyst. Preferred bisphenols have the following formula (I).
Bisphenol
(In the formula, R
a
and R
b
are the same or different, and are each a halogen atom or a univalent hydrocarbon group. p and q are integers from 0 to 4. X is
or
R
c
and R
d
are each a hydrogen atom or a univalent hydrocarbon group, R
c
and R
d
may form a ring structure, and R
e
is a divalent hydrocarbon group.)
Specific examples of the bisphenols expressed by the above formula (I) 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(4-hydroxyphenyl)-butane,
2,2-bis(4-hydroxyphenyl)octane,
1,1-bis(4-hydroxyphenyl)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, and
2,2-bis(4-hydroxy-3-bromophenyl)propane; and
bis-(hydroxyaryl)cycloalkanes such as:
1,1-bis (hydroxyphenyl)cyclopentane and
1,1-bis(4-hydroxyphenyl)cyclohexane.
Other bisphenols that can be used with the present invention are those in which X in the above formula is —O—, —S—, —SO—, or —SO
2
—, examples of which include:
dihydroxyaryl ethers such as:
4,4′-dihydroxydiphenyl ether and
4,4′-dihydroxy-3,3′-dimethyiphenyl ether;
dihydroxydiaryl sulfides such as:
4,4′-dihydroxydiphenyl sulfide and
4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfide;
dihydroxydiaryl sulfoxides such as:
4,4′-dihydroxydiphenyl sulfoxide and
4,4′-dihydroxy-33,′-dimethyldiplienyl sulfoxide; and
dihydroxydiarylsulfones such as:
4,4′-dihydroxydiphenylsulfone and
4,4′-dihydroxy-3,3′-dimethyldiphenylsulfone.
Other examples of bisphenols are the compounds expressed by the following formula (II).
(In the formula, R
f
is a halogen atom or a C
1
to C
10
hydrocarbon group or halogen-substituted hydrocarbon group, and n is an integer from 0 to 4. When n is equal to or greater than 2, the R
f
groups may be the same or different.)
Specific examples of the bisphenols expressed by this formula (II) include:
resorcin and substituted resorcins such as 3-methylresorcin, 3-ethylresorcin, 3-propylresorcin, 3-butylresorcin, 3-t-butylresorcin, 3-phenylresorcin, 3-cumylresorcin, 2,3,4,6-tetrafluororesorcin, and 2,3,4,6-tetrabromoresorcin;
catechol; and
hydroquinone and substituted hydroqluiniones such as 3-methylhydroquinone, 3-ethylhydroquinone, 3-propylhydroquinone, 3-butylhydroquinone, 3-t-butylhydro-quinone, 3-phenyihydroquinone, 3-cumylhydroquinone, 2,3,5,6-tetramethylhydroquinone, and 2,3,5,6-tetra-t-butylhydroquinone, 2,3,5,6-tetrafluorohydroquinone, and 2,3,5,6-tetrabromohydroquinone.
Furthermore, the 2,2,2′,2′-tetralhydro-3,3,3′,3′-tetramethyl-1,1
40
-spirobi-[IH-indene]-6,6′-diol expressed by the following formula (III) can also be used as the bisphenol.
Of these compounds, a bisphenol expressed by the above-mentioned formula (I) is preferable, and bisphenol A is particularly favorable.
Carbonic Diester
Specific examples of carbonic diesters that can be used include diphenyl carbonate, ditolyl carbonate, bis(chloroplIenyl) car
Sakashita Takeshi
Shimoda Tomoaki
LandOfFree
Continuous method for manufacturing polycarbonate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuous method for manufacturing polycarbonate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuous method for manufacturing polycarbonate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2847811