Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2003-03-18
2004-09-14
Boykin, Terressa (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S198000, C558S085000, C558S089000
Reexamination Certificate
active
06790928
ABSTRACT:
TECHNICAL FIELD
The present invention relates to improvements in the thermal stability of polycarbonate resins produced by transesterification.
BACKGROUND ART
Polycarbonates obtained by interfacial polymerization of an aromatic dihydroxy compound such as 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as BPA) with phosgene in the presence of an acid binder have satisfactory impact resistance and other mechanical properties, and exhibit high thermal resistance and transparency. They are thereby used as optical materials in, for example, lenses, prisms, and optical disk substrates.
However, such polycarbonates prepared by using BPA alone as the aromatic dihydroxy compound have a high photoelastic constant and a relatively low melt flowability to thereby yield molded articles showing a high degree of double refraction. In addition, they suffer an imbalance between refractive index and Abbe's number indicating the degree of dispersion, with a low Abbe's number of 30 but a high reflective index of 1.58, so they do not have sufficient capabilities for wide use in, for example, optical recording materials and optical lenses. To avoid these disadvantages of BPA-derived polycarbonates, a copolycarbonate of BPA and tricyclo(5.2.1.0
2,6
)decane-dimethanol (hereinafter referred to as TCDDM) has been proposed (Japanese Patent Application Laid-open No. 64-66234).
However, the production process for copolycarbonates only teaches (1) polycondensation of a bischloroformate of BPA with TCDDM or TCDDM and BPA, (2) polycondensation of a bischloroformate of TCDDM with BPA or BPA and TCDDM, and (3) polycondensation of a mixture of a bischloroformate of BPA and a bischloroformate of TCDDM with BPA and/or TCDDM. To produce copolymers of an aliphatic dihydroxy compound and an aromatic dihydroxy compound in this type of two-stage reaction, a bischloroformate of a dihydroxy compound is initially produced, and the bischloroformate is then polycondensed with a dihydroxy compound. The two-stage reaction therefore complicates production process steps and thereby invites increased production cost.
A transesterification process of polycondensing a carbonic acid diester with a dihydroxy compound in a molten state is known as another possible production process. However, in the production process, the polymerization is performed at high temperatures for a long time to thereby often result in colored reaction products, and a catalyst remained in the polymer causes deterioration in physical properties of the polymer. This tendency is noticeable especially in polycarbonates having an aliphatic structure.
DISCLOSURE OF INVENTION
Accordingly, an object of the present invention is to provide a process for stabilizing a polycarbonate produced by transesterification.
After intensive investigations under these circumstances, the present inventors have found that very satisfactory thermal stability can be imparted to a polycarbonate prepared by transesterification by adding a specific phosphite compound to the polycarbonate. The present invention has been accomplished based on these findings.
Specifically, the present invention provides, in one aspect, a process for producing a polycarbonate, comprising the steps of melt polycondensing a carbonic acid diester and a dihydroxy compound in the presence of a catalytic alkali metal and/or alkaline earth metal to yield a polycarbonate, and incorporating 0.0001 to 0.1 part by weight of a phosphite compound represented by following Formula (I) into 100 parts by weight of the polycarbonate:
wherein Rs are each one of a hydrogen atom, an alkyl group containing 1 to 18 carbon atoms, an aryl group, and an oxyalkyl group containing 1 to 8 carbon atoms, where the two Rs are not concurrently hydrogen atoms.
The present invention also provides, in another aspect, the process for producing a polycarbonate in which the dihydroxy compound is one of an aromatic dihydroxy compound, an aliphatic dihydroxy compound, and a mixture of both.
The present invention provides, in yet another aspect, the process for producing a polycarbonate in which 0.0001 to 0.3 part by weight of one of a phosphonium salt of an aromatic sulfonic acid, an aromatic sulfonic acid ester, or an alkylsulfuric acid is incorporated into 100 parts by weight of the polycarbonate.
Best Mode for Carrying Out the Invention
The present invention will be described in detail below.
Aromatic carbonic acid diesters for use in the present invention are compounds represented by following Formula (II):
wherein Ars are the same or different and are each a monovalent aromatic group.
Examples of the aromatic carbonic acid diesters represented by Formula (II) include diphenyl carbonate, ditolyl carbonate, dixylyl carbonate, bis(propylphenyl) carbonate, bis(octylphenyl) carbonate, bis(nonylphenyl) carbonate, bis(methoxyphenyl) carbonate, and bis(ethoxyphenyl) carbonate, of which diphenyl carbonate is typically preferred. The chlorine content in the aromatic carbonic acid diester is preferably less than or equal to 1 ppm. The amount of the aromatic carbonic acid diester is preferably from 0.97 to 1.2 mole and more preferably from 0.99 to 1.10 mole per mole of the total dihydroxy compound(s).
Dihydroxy compounds for use in reactions according to the present invention include aromatic dihydroxy compounds and aliphatic dihydroxy compounds.
Such aromatic dihydroxy compounds for use in the reactions according to the present invention include compounds represented by following Formula (III):
wherein X is a single bond or
wherein R
3
and R
4
are each one of a hydrogen atom, an alkyl group containing 1 to 10 carbon atoms, and a phenyl group, where R
3
and R
4
may be combined to form a ring; R
1
and R
2
are the same or different and are each one of a hydrogen atom, an alkyl group containing 1 to 10 carbon atoms, and a halogen; and m and n are each a number of substituents and are each an integer from 0 to 4.
Examples of the dihydroxy compounds represented by Formula (III) include bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane, 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, 1,1-bis(4-hydroxyphenyl)cyclohexane, and other bisphenols; 4,4′-dihydroxydibiphenyl, 3,3′,5,5′-tetramethyl-4,4′-dihydroxybiphenyl, and other biphenols; bis(4-hydroxyphenyl) sulfone, bis(4-hydroxyphenyl) sulfoxide, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl) ether, and bis(4-hydroxyphenyl) ketone. Among them, 1,1-bis(4-hydroxyphenyl)cyclohexane (hereinafter briefly referred to as BPZ) is typically preferred. Two or more of the aromatic dihydroxy compounds represented by Formula (III) can be used in combination.
The aliphatic dihydroxy compounds include dihydroxy compounds having an alicyclic structure. Examples of such dihydroxy compounds having an alicyclic structure are tricyclo(5.2.1.0
2,6
)decanedimethanol, &bgr;,&bgr;,&bgr;′,&bgr;′-tetramethyl-2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-diethanol (spiroglycol), entacyclo[9.2.1.1
3,9
.0
2,10
.0
4,8
]-pentadecane-dimethanol, pentacyclo[9.2.1.1
4,7
.0
2,1
.0.0
3,8
]pentadecane-dimethanol, 2,6-decalindimethanol, and 1,4-cyclohexane-dimethanol. Among them, tricyclo(5.2.1.0
2,6
)decanedimethanol represented by following Formula (IV) is typically preferred.
These dihydroxy compounds having an alicyclic structure contain a carbonyl group, if any, as an impurity in an amount in terms of KOH of less than or equal to 1.0 mg/g, preferably less than or equal to 0.5 mg, and more preferably less than or equal to 0.1 mg. The contents of chlorine and metallic ions are preferably each less than or equal to 1 ppm.
Copolycarbonates can be prepared by using two or more of these dihydroxy compounds in combination. Among such copolycarbonates, aromatic-aliphatic copolycarbonates using an aromatic dihydroxy compound and an aliphatic dihydroxy compound as raw materials are suitable
Tanaka Hiroaki
Yoshida Shu
Boykin Terressa
Mitsubishi Gas Chemical Company Inc.
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