Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2002-11-01
2003-12-02
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
C264S219000, C528S198000
Reexamination Certificate
active
06657038
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the preparation of copolycarbonates prepared by the melt polymerization reaction of at least two dihydroxy aromatic compounds with one or more diaryl carbonates, at least one of the dihydroxy aromatic compounds being having a substantial degree of volatility and thus being difficult to incorporate into the product copolycarbonate by conventional methods.
Polycarbonates have excellent impact resistance and other mechanical properties as well as excellent heat resistance and transparency. Polycarbonates are widely used in applications ranging from football helmets to automobile parts to transparent security windows. More recently, polycarbonates have also proven to be the material of choice for optical media applications such as optical discs, for example compact discs (CD) and digital versatile discs (DVD). Conventional polycarbonates are usually produced by (1) an interfacial polymerization, in which bisphenol A (BPA) is reacted directly with phosgene or (2) a melt polymerization process in which BPA is transesterified with a carbonic acid diester such as diphenyl carbonate (DPC). For many applications, there has been a need for materials possessing the fundamental characteristics of transparency and toughness inherent in BPA polycarbonate but possessing, in addition, certain improvements in physical properties relative those possessed by bisphenol A polycarbonate (BPA-PC), for example birefringence. For some applications improved chemical resistance relative to BPA polycarbonate is required, for example in certain medical and automotive applications. Copolycarbonates are materials frequently possessing the fundamental traits of BPA polycarbonate, transparency and toughness, but in certain instances also possessing improved performance characteristics for a given application relative to BPA polycarbonate.
One example of such a copolycarbonate comprises repeat units derived from resorcinol or hydroquinone in addition to repeat units derived from bisphenol A. The incorporation of resorcinol-derived and hydroquinone-derived repeat units into a BPA-polycarbonate confers excellent melt flow properties, molding properties, solvent and heat resistance, while maintaining the excellent mechanical properties and transparency inherent in bisphenol A polycarbonate. Such copolycarbonates can be prepared by interfacial polymerization, melt polymerization, or solid state polymerization. The present invention relates to an improved method to prepare these and related copolycarbonates using the melt polymerization method.
In conventional melt polycondensation processes, bisphenol A polycarbonate is prepared by reacting bisphenol A with diphenyl carbonate in a molten state. Generally a catalyst comprising a quaternary ammonium salt such as tetramethylammonium hydroxide (TMAH), and an alkali or alkali earth metal hydroxide, such as sodium hydroxide (NaOH), is used to catalyze the polymerization reaction. During the melt polymerization process the reactants and products are subjected to high temperature and low pressure while by-product phenol is distilled from the reaction mixture. While copolycarbonates comprising repeat units derived from relatively volatile dihydroxy aromatic compounds, such as resorcinol and hydroquinone, may be prepared in a similar fashion much of the volatile comonomer may be lost during the polymerization reaction. Loss of the volatile comonomer presents significant engineering challenges, and with them stark economic penalties, when attempting to manufacture copolycarbonate comprising repeat units derived from one or more relatively volatile dihydroxy aromatic compounds via the melt polymerization process. The present invention solves these and other problems and provides a method for preparing copolycarbonates which incorporates volatile comonomers with greater efficiency than known methods.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a method of preparing a copolycarbonate, said method comprising contacting under melt polymerization conditions at least one first dihydroxy aromatic compound, and at least one second dihydroxy aromatic compound, with at least one diaryl carbonate having structure I
wherein R
1
is independently at each occurrence a halogen atom, nitro group, cyano group, C
1
-C
20
alkyl group, C
4
-C
20
cycloalkyl group, or C
6
-C
20
aryl group; and p and q are independently integers 0-5;
and at least one melt polymerization catalyst, said catalyst comprising at least one metal hydroxide and at least one quaternary phosphonium salt having structure II
wherein R
2
-R
5
are independently a C
1
-C
20
aliphatic radical, C
4
-C
20
cycloaliphatic radical or a C
4
-C
20
aromatic radical, and X
−
is an organic or inorganic anion;
said first dihydroxy aromatic compound having a boiling point at atmospheric pressure, said boiling point being less than about 340° C.
In a further aspect the present invention relates to copolycarbonates prepared by the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. In the following specification and the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings:
The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
As used herein the term “copolycarbonate” refers to polycarbonates incorporating repeat units derived from at least two dihydroxy aromatic compounds and includes and copolyestercarbonates, for example a polycarbonate comprising repeat units derived from resorcinol, bisphenol A, and dodecandioic acid.
“BPA” is herein defined as bisphenol A or 2,2-bis(4-hydroxyphenyl)propane.
As used herein, the term “copolycarbonate of bisphenol A” refers to a copolycarbonate comprising repeat units derived from BPA and at least one other dihydroxy aromatic compound.
As used herein, the term “melt polycarbonate” refers to a polycarbonate made by the transesterification of a diaryl carbonate with a dihydroxy aromatic compound.
“Catalyst system” as used herein refers to a catalyst or catalysts that catalyze the transesterification of a dihydroxy aromatic compound with a diaryl carbonate in the preparation of melt polycarbonate.
“Catalytically effective amount” refers to an amount of a catalyst at which catalytic performance is exhibited.
As used herein the term “Fries product” is defined as a structural unit of the product polycarbonate which upon hydrolysis of the product polycarbonate affords a carboxy-substituted dihydroxy aromatic compound bearing a carboxy group adjacent to one or both of the hydroxy groups of said carboxy-substituted dihydroxy aromatic compound. For example, bisphenol A polycarbonate prepared by a melt reaction method in which Fries reaction occurs, affords 2-carboxy bisphenol A upon complete hydrolysis of the product polycarbonate.
The terms “Fries product” and “Fries group” are used interchangeably herein.
The terms “Fries reaction” and “Fries rearrangement” are used interchangeably herein.
As used herein the term “dihydroxy aromatic compound” means a an aromatic compound which comprises two hydroxy groups, for example a bisphenol such as bisphenol A or a dihydroxy benzene such as resorcinol.
As used herein the term “hydroxy aromatic compound” means a phenol, such as phenol or p-cresol, comprising a single reactive hydroxy group.
As used herein the term “aliphatic radical” refers to a radical having a valence of at least one comprising a linear or branched array of atoms which is not cyclic. The array may include heteroatoms such as nitrogen, sulfur and oxygen or may be composed exclusively of carbon and hydrog
Kamps Jan Henk
Lens Jan Pleun
Boykin Terressa M.
Caruso Andrew J.
General Electric Company
Patnode Patrick K.
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