Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-12-21
2001-02-13
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
C528S196000
Reexamination Certificate
active
06187896
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aromatic polycarbonate composition. More particularly, this invention relates to an aromatic polycarbonate composition excellent in hue and thermal stability.
BACKGROUND OF THE INVENTION
Known as representative prior art techniques for producing an aromatic polycarbonate are processes in which 2,2-bis(4-hydroxyphenyl)propane (hereinafter abbreviated as bisphenol A) is reacted with a compound capable of incorporating a carbonate bond, such as phosgene or a carbonic diester. Of those processes, a transesterification process has advantages in operation and cost over a phosgene process (interfacial polymerization process) because the steps thereof are relatively simple. In addition, the transesterification process has recently come to be thought better of from the standpoint of environmental protection, because neither phosgene, which is highly toxic, nor a halogenated solvent, e.g., methylene chloride, is used in the process.
However, practical use of the transesterification process for large-scale industrial production is still limited because it has some drawbacks over the phosgene process concerning polycarbonate properties and the process itself. In particular, a serious problem concerning properties of the polycarbonate obtained by the transesterification process is that the hue of the polycarbonate deteriorates upon heating.
Various investigations have been made so far in order to overcome the above problem. Examples thereof include addition of an acidic compound and an epoxy compound (see JP-A-4-175368; the term “JP-A” as used herein means an “unexamined published Japanese patent application”), addition of a phosphite compound (see JP-A-3-265625), and addition of a hindered phenol compound (see JP-A-4-41525). However, even with the incorporation of these additives into a polycarbonate, it has still been difficult to obtain a polycarbonate composition having sufficient thermal stability.
SUMMARY OF THE INVENTION
In view of the problems described above, an object of the present invention is to provide a highly thermally stable, aromatic polycarbonate composition which maintains high transparency and a satisfactory hue even in a high temperature and high humidity atmosphere and is suitable for use in applications such as optical disks and medical apparatuses.
As a result of intensive investigations in seeking for more effective additives, it has been found that exceedingly high thermal stability can be imparted to a polycarbonate by adding thereto a given amount of a phosphorus compound having a structure represented by the following formula (1). The present invention has been completed based on this finding.
wherein the eight R's may be the same or different and each represent a hydrogen atom or an optionally substituted, aliphatic or aromatic, univalent group having 1 to 18 carbon atoms.
Accordingly, the present invention provides an aromatic polycarbonate composition comprising: a polycarbonate obtained by reacting at least one aromatic dihydroxy compound with a compound capable of incorporating a carbonate bond; and a phosphorus compound represented by the above formula (1).
DETAILED DESCRIPTION OF THE INVENTION
The polycarbonate as a constituent component of the composition of the present invention is obtained by reacting at least one aromatic dihydroxy compound with a compound capable of incorporating a carbonate bond. The “aromatic dihydroxy compound” is represented by the following general formula (2):
wherein A is a single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms or a bivalent atom or group represented by —O—, —S—, —CO—, —SO— or —SO
2
—; X and Y are the same or different and each are a halogen atom or a hydrocarbon group having 1 to 6 carbon atoms; and p and q are the same or different and each are an integer of 0 to 2.
Typical examples of the aromatic dihydroxy compound include bisphenols such as bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane [bisphenol A], 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-t-butylphenyl) propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane,4,4-bis(4-hydroxyphenyl)heptane, and 1,1-bis(4-hydroxyphenyl)-cyclohexane; biphenols such as 4,4′-dihydroxybiphenyl and 3,3′,5,5′-tetramethyl-4,4′-dihydroxybiphenyl; and bis(4-hydroxyphenyl) sulfone, bis(4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ether, and bis(4-hydroxyphenyl) ketone. Of those, bisphenol A is preferable. Although those aromatic dihydroxy compounds are generally used alone, a mixture of two or more of those may be used according to need to obtain a copolymer.
Typical examples of the “compound capable of incorporating a carbonate bond” include phosgene; carbonic diesters such as diphenyl carbonate, di-p-tolyl carbonate, phenyl p-tolyl carbonate, dimethyl carbonate and diethyl carbonate; and the bischloroformates of aromatic dihydroxy compounds. Of those, phosgene and diphenyl carbonate are preferable.
Where a carbonic diester is used in the reaction (transesterification process) as the compound capable of incorporating a carbonate bond, a dicarboxylic acid or a dicarboxylic acid ester may be used together with the carbonic diester in an amount of preferably 50 mol % or smaller, and more preferably 30 mol % or smaller. Examples of the dicarboxylic acid or dicarboxylic acid ester include terephthalic acid, isophthalic acid, diphenyl terephthalate and diphenyl isophthalate. Where such a carboxylic acid or carboxylic acid ester is used in combination with a carbonic diester, a polyester carbonate is obtained.
Where phosgene is used in the reaction (phosgene process) as the compound capable of incorporating a carbonate bond, this reaction is generally conducted in the presence of an acid acceptor and a solvent. Examples of the acid acceptor include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and pyridine. Examples of the solvent include halogenated hydrocarbons such as methylene chloride and chlorobenzene. For the purpose of accelerating the reaction, a catalyst may be used, such as a tertiary amine or a quaternary ammonium salt. It is desirable to use as a molecular weight regulator a chain terminator such as phenol, p-t-butylphenol, p-cumylphenol or isooctylphenol. The reaction is preferably conducted at a temperature of generally from 0 to 40° C. for from several minutes to 5 hours while maintaining the pH of the system generally at 10 or higher.
Where the aromatic dihydroxy compound and the carbonic diester are subjected to melt polycondensation to produce a polycarbonate by the transesterification process, a catalyst is generally used. In polycarbonate production according to the present invention, there is no limitation on the kind of catalyst. However, catalysts generally used are basic compounds such as alkali metal compounds, alkaline earth metal compounds, basic boron compounds, basic phosphorus compounds, basic ammonium compounds and amine compounds. Those may be used alone or in combination of two or more thereof. The amount of the catalyst used is generally from 1×10
−9
to 1×10
−3
mol, and preferably from 1×10
−7
to 1×10
−4
mol, per mole of the aromatic dihydroxy compound.
Examples of the alkali metal compounds include inorganic alkali metal compounds such as the hydroxides, carbonates and hydrogen carbonates of lithium, sodium, potassium, rubidium and cesium, and organic alkali metal compounds such as the salts of these alkali metals with alcohols, phenols and organic carboxylic acids. Of those alkali metal compounds, cesium compounds are preferable. Specifically, the most preferred cesium compounds are cesium carbonate, cesium hydrogen carbonate and cesium hydroxide.
Examples of the alkaline earth metal compounds include inorganic alkaline earth metal compou
Hayashi Katsushige
Kawai Michio
Nakajima Masayuki
Takano Junji
Boykin Terressa M.
Mitsubishi Gas Chemical Company Inc.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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