Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-10-14
2002-01-15
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
06339138
ABSTRACT:
The present application is a U.S. non-provisional application based upon and claiming priority from Japanese Application Nos. HEI 10-313705, HEI 10-313706, HEI 10-313707, and HEI 10-313708, which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
This invention relates to a manufacturing method of polycarbonates by an ester interchange reaction. More specifically, it relates to a manufacturing method of high molecular weight aromatic polycarbonates with improved color by an ester interchange reaction of an aromatic dihydroxy compound with a carbonic acid diester.
Recently, aromatic polycarbonates have been widely adopted for use as engineering plastics in many fields because of their excellent mechanical properties such as high impact resistance and other excellent characteristics such as heat resistance and transparency.
The so-called phosgene method of manufacturing aromatic polycarbonates is used commercially, whereby an aromatic dihydroxy compound such as bisphenol is reacted with phosgene by interfacial polycondensation. However, the phosgene method currently employed in industry is associated with a number of problems, including the highly toxic nature of phosgene, the need for handling of large quantities of sodium chloride generated as a by product, and the public health and environmental issues associated with methylene chloride, the solvent conventionally used in this reaction.
In addition to use of the phosgene method, it is known that an ester interchange reaction (melt method) between an aromatic dihydroxy compound and a carbonate diester using an alkali metal salt as the catalyst may be utilized to manufacture aromatic polycarbonates. This method of manufacturing aromatic polycarbonates has attracted recent attention because it is inexpensive. Also, toxic substances such as phosgene and methylene chloride are not required, so it is more advantageous from a health and environmental perspective.
To achieve high molecular weight polycarbonates with excellent mechanical properties when manufacturing polycarbonates by this melt method, the unreacted monomers such as bisphenol and diphenyl carbonate must be distilled from the highly viscous polycarbonate melt. This requires that the polycarbonate products be subjected to high temperatures of 250 to 330° C., under a high vacuum over long periods under high vacuum. However, the melt method is often associated with problems in achieving excellent quality in terms of a balance between color and high molecular weight. This is due to the alkali metal acting as a catalyst in the ester interchange reaction and the occurrence of side reactions such as decarboxylation and the Kolbe-Schmitt reaction. These side reactions produce branched polycarbonates (as shown in the formula below), generate cross linked products and cause coloring of the polycarbonate produced (“Polycarbonate Resins,” Nikkan Kogyo Shinbun, Sep. 30, 1969.)
(X indicates a linear or branched chain hydrocarbon group).
As a means to solve these problems, Japanese Patent No. H4-89824 disclosed the use of (1) nitrogen containing basic compounds, (2) alkali metal compounds or alkaline earth metal compounds, and (3) boric acid or borate ester compounds as catalysts. Japanese Patent No. H4-46928 disclosed the use of (1) electron donor amine compounds and (2) alkali metal compounds or allkaline earth metal compounds as catalysts. Japanese Patent No. H4-175368 disclosed a method whereby melt polymerization in the presence of an alkaline compound catalyst was carried out, followed by the addition of acidic compounds and epoxy compounds to the reaction products.
However, although the above disclosed methods helped to improve problems such as coloring, they did not always produce satisfactory results.
In addition, Japanese Patent No. H7-53704 disclosed a method of manufacturing polycarbonates that reduced side reactions and improved color. That manufacturing method of polycarbonates described (1) a single compound produced from (a) an alkali metal compound or al alkaline earth metal compound and (b) a non-volatile acid; or (2) a mixture from (a) an alkali metal compound or an alkaline earth metal compound and (b) a non-volatile acid. The described single compound or the mixture was then rendered weakly acidic in an aqueous solution and used as a catalyst. However, the rate of polymerization achieved by that disclosed method was not completely satisfactory.
We (the inventors) successfully accomplished the present invention through diligent research efforts, taking into consideration the various types of problems described above. We have invented a means to efficiently manufacture polycarbonates wherein side reactions are inhibited and color is improved.
BRIEF SUMMARY OF THE INVENTION
This invention is a method to manufacture polycarbonates by means of an ester interchange reaction of a dihydroxy compound and carbonate diester. The method utilizes a dihydroxy compound and a carbonate diester as raw materials, in which the total amount of impurities (alkali metal compounds and alkaline earth metal compounds) is no greater than 1×10
−7
mole per 1 mole of the dihydroxy compound. The reaction is catalyzed by an alkali metal phosphite per 1 mole of the dihydroxy compound. Preferably, 1×10
−7
to 2×10
−6
mole of alkali metal phosphite per 1 mole of the dihydroxy compound should be used. The alkali metal phosphite should be at least one compound selected from among the group of lithium dihydrogen phosphite, sodium dihydrogen phosphite, and potassium dihydrogen phosphite.
DETAILED DESCRIPTION OF THE INVENTION
The following are further details of this invention relating to a method for manufacturing polycarbonates.
First, an explanation is presented about the raw materials for polycondensation used as the manufacturing method for polycarbonates related to this invention.
Raw Material For Polycondensation
A dihydroxy compound and a carbonic acid diester are used as raw materials for the polycondensation.
There is no particular restriction on the type of dihydroxy compound that can be employed. For example, bisphenol compounds represented by the general formula (I) below can be used
(In the formula R
a
and R
b
each represent a halogen atom or a monovalent hydrocarbon group and may be the same or different. The p and q represent integers from 0 to 4.
The X represents
or
R
c
and R
d
each represent a hydrogen atom or a monovalent hydrocarbon group, and may form cyclic structure. R
e
is a divalent hydrocarbon group.)
Specific examples of the types of bisphenol compounds that may be represented by formula [I] above include the following:
1,1-bis(4-hydroxypenyl) methane;
1,1-bis(4-hydroxypenyl) ethane;
2,2-bis(4-hydroxypenyl) propane (hereinafter referred to as “bisphenol A”);
2,2-bis(4-hydroxypenyl) butane;
2,2-bis(4-hydroxypenyl) octane;
1,1-bis(4-hydroxypenyl) propane;
1,1-bis(4-hydroxypenyl) n-butane;
bis(4-hydroxypenyl) phenylmethane;
2,2-bis(4-hydroxy-1-methylpenyl) propane;
1,1-bis(4-hydroxy-t-butylpenyl) propane;
2,2-bis(4-hydroxy-3-bromophenyl) propane and other bis(hydroxyalyl) alkanes;
1,1-bis(4-hydroxypenyl) cyclopentane;
1,1-bis(4-hydroxypenyl) cyclohexane and other bis(hydroxyaryl) cycloalkanes;
The X in the bisphenol shown in the above formula may represent and —O—, —S—, —SO—, or —SO
2
— group, for example:
4,4′-dihyrdoxydiphenyl ether;
4,4′-dihyrdoxy-3,3′-dimethyldiphenyl ether and other bis(hydroxyaryl) ether;
4,4′-dihyrdoxydiphenyl sulfide;
4,4′-dihyrdoxy-3,3′-dimethyldiplhenyl sulfide and other bis(hydroxydiaryl) sulfide;
4,4′-dihyrdoxydiphenyl sulfoxide;
4,4′-dihyrdoxy-3,3′-dimethyldiphenyl sulfoxide and other bis(hydroxydiaryl) sulfoxide;
4,4′-dihyrdoxydiphenyl sulfone;
or 4,4′-dihyrdoxy-3,3′-dimethyldiphenyl sulfone and other bis(hydroxydiaryl) sulfone.
In addition, the bisphenol used may be a compound represented by formula [II] below.
(In the formula, R
f
may represent a halogen atom, a hydrocarbon group containing
Ikeda Akio
Kimura Takato
McCloskey Patrick Joseph
Shimoda Tomoaki
van Hout Henricus Hubertus Maria
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