Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-05-05
2001-09-11
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
06288203
ABSTRACT:
TECHNICAL FIELD
The present invention relates to processes for producing polycarbonate, and more precisely, to a process for producing polycarbonate by direct solid-phase polymerization of an amorphous prepolymer, and to a process for producing polycarbonate by solid-phase polymerization of a mixture comprising an amorphous prepolymer and a crystalline prepolymer.
BACKGROUND ART
At present, the main current of polycarbonate production is interfacial polycondensation that starts from phosgene and bisphenol A and uses a reaction solvent of methylene chloride.
However, phosgene to be used in the interfacial polycondensation is highly toxic, and methylene chloride to be used therein is a halide solvent of which the use shall be much restricted for the protection of the environment. Therefore, the development of novel techniques substitutable for this is desired.
Recently proposed were melt interesterification (transesterification) and solid-phase polymerization.
The melt interesterification is to polymerize a dihydroxy compound and a dicarbonate compound through interesterification of the two in the presence of no solvent; while the solid-phase polymerization is to polymerize a prepolymer under heat in a solid phase.
It is expected that those new techniques solve the problems of the conventional interfacial polymerization and stably give polycarbonate of high quality.
Some methods of solid-phase polymerization have been disclosed, in which a starting, amorphous polycarbonate prepolymer is processed with a solvent or heated for crystallization to make it have a degree of crystallinity of about 20% (melting point: 190 to 210° C.), and then polymerized in a solid phase at about 200° C. or so in an inert gas stream of, for example, nitrogen, argon, helium or carbon dioxide (see Japanese Patent Application Laid-Open (JP-A) Nos. Sho-63-223035, Sho-64-16826, Sho-64-38433). In those, the starting prepolymer is crystallized prior to the solid-phase polymerization to have an elevated melting point so that it can be polymerized in a solid phase at high temperatures within a shortened period of time.
However, where the crystallization treatment is effected under heat in an inert gas stream such as that mentioned above, it is said that it takes a long period of time of from several tens hours to several hundreds hours since the crystallization rate of the prepolymer is very low (see Polycarbonate Resin Handbook, published by Nikkan Kogyo Shinbun Co.).
As in the above, the crystallization treatment is an indispensable pre-treatment for the conventional solid-phase polymerization.
The conventional solid-phase polymerization is effected in an inert gas stream (see Japanese Patent Publication (JP-B) No. Hei-6-99551). The inert gas includes nitrogen, carbon dioxide, argon and helium. However, the essential function of the inert gas used is to lower the partial pressure of the side product formed in a gaseous phase, or that is, to control the diffusion of the side product into the particulate prepolymer being polymerized.
Having known the prior art as above, we, the inventors herein provide the present invention, of which the object is to provide improved processes for producing polycarbonate through solid-phase polymerization. The processes of the invention simplify the step of pre-treatment for crystallization of prepolymers to be effected prior to the solid-phase polymerization, and the time for the processes is much shortened.
DISCLOSURE OF THE INVENTION
The present inventors have assiduously studied, and, as a result, have found that a particulate, substantially amorphous polycarbonate prepolymer, or a mixture comprising such a powder amorphous polycarbonate prepolymer and a particulate crystalline prepolymer can be polymerized in a solid phase, while being kept in a fluid state under an atmosphere containing a swelling solvent gas, with no troubles of fusion or blocking of the prepolymer grains being polymerized. On the basis of this finding, the inventors have completed the present invention.
Specifically, the present invention is summarized as follows.
1. A process for producing polycarbonate, which comprises polymerizing a substantially amorphous polycarbonate prepolymer in a solid phase under an atmosphere containing a swelling solvent gas.
2. A process for producing polycarbonate, which comprises polymerizing a substantially amorphous polycarbonate prepolymer in a solid phase under an atmosphere containing a swelling solvent gas, while the prepolymer is kept in a fluid state.
3. The process for producing polycarbonate of 1 or 2, wherein the solid-phase polymerization is effected under an atmosphere containing a swelling solvent gas and at least one gas selected from poor solvent gases and inert gases.
4. The process for producing polycarbonate of any one of 1 to 3, wherein a mixture comprising a substantially amorphous polycarbonate prepolymer and a crystalline polycarbonate prepolymer is polymerized.
5. The process for producing polycarbonate of any one of 1 to 4, wherein the substantially amorphous polycarbonate prepolymer is a particulate one.
6. The process for producing polycarbonate of 4 or 5, wherein the crystalline polycarbonate prepolymer is a particulate one.
BEST MODES OF CARRYING OUT THE INVENTION
Typical embodiments of the present invention are described in detail hereinunder.
The processes for producing polycarbonate of the invention include (A) a step of preparing a starting material of an amorphous polycarbonate prepolymer, (B) a step of preparing a starting material of a mixture comprising an amorphous polycarbonate prepolymer and a crystalline polycarbonate prepolymer, and (C) a step of polymerizing particulates of the starting material in a swollen solid phase under an atmosphere containing a swelling solvent gas to give polycarbonate. These steps are described in detail.
(A) Step of Preparing Amorphous Polycarbonate Prepolymer
The amorphous polycarbonate prepolymer to be subjected to solid-phase polymerization in the invention may be prepared in any known method of, for example, interfacial polymerization or melt interesterification.
The solid-phase polymerization in the invention is for condensation of prepolymer, and consists essentially of interesterification of the carbonate group, such as an aryl or alkyl carbonate group constituting one terminal of the prepolymer with the hydroxyl group constituting the other terminal thereof. Therefore, for this, the constitutional ratio of the terminal groups of the prepolymer, or that is, the ratio of the former to the latter is generally from 0.1/1 to 5/1, but preferably from 0.5/1 to 2/1, more preferably from 0.8/1 to 1.4/1, by mol, in view of the reaction efficiency.
In order to produce the prepolymer having such a predetermined constitutional ratio of the terminal groups through interfacial polymerization, prepolymers having been once prepared must be so processed that they have the desired, predetermined constitutional ratio of the terminal groups, for example, by blending a phenol-terminated carbonate prepolymer and a hydroxyl-terminated carbonate prepolymer both having been prepared separately, in a suitable ratio to make the prepolymer blend have the intended constitutional ratio of the terminal groups. As opposed to the interfacial polymerization that requires the post-treatment, preferred is interesterification capable of easily producing the intended prepolymer having the intended constitutional ratio of the terminal groups.
Therefore, hereinunder described in detail is the interesterification to give the prepolymer for use in the invention.
As the starting materials, most generally used are aromatic dihydroxy compounds as combined with dicarbonate compounds.
Of those, the aromatic dihydroxy compounds include, for example, bis(hydroxyaryl)alkanes such as bis(4-hydroxyphenyl)methane, bis(3-methyl-4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(2-t-butyl-4-hydroxy-3-methylphenyl)ethane, 1,1-bis(2-t-butyl-4-hydroxy-3-methylphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A: BPA), 2,2-bis(3-me
Shishikura Akihiro
Takahashi Seiji
Boykin Terressa M.
Idemitsu Petrochemical Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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