Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-08-01
2002-06-25
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
06410678
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aromatic polycarbonate which has a small content of a specific metal element and high durability and stability particularly when it is used at a high temperature and a high humidity for a long time, production method and molded products thereof.
DESCRIPTION OF THE PRIOR ART
Aromatic polycarbonates are excellent engineering plastics which are excellent in color, transparency and mechanical strength. Since they have recently been used for various purposes and under wider environmental conditions, high durability and stability are required of the polycarbonates to retain the above characteristic properties even when they are used under high-temperature and high-humidity conditions for a long time.
It is reported that conventional aromatic polycarbonates have problems with durability and stability because they experience a reduction in molecular weight and deterioration in color and transparency when they are used under high-temperature and high-humidity conditions for a long time. A reduction in molecular weight lowers the mechanical strength of a polymer and deterioration in color and transparency detracts greatly from the advantages of the aromatic polycarbonates.
Since it is apprehended that deterioration by moist heat is caused by trace amounts of impurities contained in the polymer, especially metal compounds though the definite chemical structures of chemical species existent in the polymer are unknown, studies are being made on the method of purifying raw materials and the polymer and the effect of reducing the contents of metals for heat resistant stability.
JP-A 5-148355 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses an aromatic polycarbonate having an iron content of 5 ppm or less and a sodium content of 1 ppm or less and JP-A 6-32885 discloses a polycarbonate having a total content of iron, chromium and molybdenum of 10 ppm or less and a total content of nickel and copper of 50 ppm or less.
JP-A 2-175722 teaches that a polycarbonate having an improved color tone is obtained by reducing the total content of hydrolyzable chlorine the content of sodium ions and iron ions in raw materials.
JP-A 11-310630 discloses a method of producing an aromatic polycarbonate by reducing impurities contained in bisphenol A as a raw material, such as iron to 10 ppb by weight and chroman-based impurities to 40 ppm by weight. In the method, some results are achieved by improving color tone, heat resistant stability and gel.
In any one of the above cases, the contents of metals disclosed in examples in which the optimal conditions are realized are still high in the order of ppm and unsatisfactory to retain the excellent color, transparency and mechanical strength of an aromatic polycarbonate for a long time under a severe moist heat condition disclosed by the present invention.
Metal species to be reduced as impurities are limited to sodium, iron and some transition metals. Required durability and stability cannot be achieved under severe conditions simply by reducing the contents of these metals.
Further, it has been revealed from researches conducted by the present inventors that the stability of a polymer is not achieved simply by reducing the amounts of impurities and that the relationship between the amount of a specific impurity contained in the raw materials and an ester exchange catalyst as well as the structural characteristics of a polycarbonate molecule are important factors. Attempts have been made to reduce the number of terminal phenolic hydroxyl groups in the molecule of a polycarbonate and not more than that is made.
Problems to be Solved by of the Invention
It is an object of the present invention to provide an aromatic polycarbonate which has excellent durability and stability and can retain its excellent color, transparency and mechanical strength for a long time under a moist heat condition which cannot be conceived in the prior art.
It is another object of the present invention to provide an industrially advantageous method of producing the above aromatic polycarbonate of the present invention.
It is still another object of the present invention to provide a molded product, for example, injection molded product of the above aromatic polycarbonate of the present invention.
Other objects and advantages of the present invention will become apparent from the following description.
Means for Solving the Problems
Firstly, according to the present invention, the above objects and advantages of the present invention are attained by an aromatic polycarbonate which comprises a main recurring unit represented by the following formula (1):
wherein R
1
and R
2
are each independently a hydrogen atom, alkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, cycloalkyl group having 6 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms, cycloalkoxy group having 6 to 20 carbon atoms or aryloxy group having 6 to 20 carbon atoms, m and n are each independently an integer of 0 to 4, and X is a single bond, oxygen atom, carbonyl group, alkylene group having 1 to 20 carbon atoms, alkylidene group having 2 to 20 carbon atoms, cycloalkylene group having 6 to 20 carbon atoms, cycloalkylidene group having 6 to 20 carbon atoms, arylene group having 6 to 20 carbon atoms or alkylene-arylene-alkylene group having 6 to 20 carbon atoms, and terminal groups consisting essentially of aryloxy groups (A) and phenolic hydroxyl groups (B), the (A)/(B) molar ratio being 95/5 to 40/60, and which has a melt viscosity stability of 0.5% or less, a sodium metal element content of 100 ppb or less and a content of each of first elements, Ni, Pb, Cr, Mn and Fe of 70 ppb or less.
Secondly, according to the present invention, the above objects and advantages of the present invention are attained by molded products of the aromatic polycarbonate of the present invention.
Thirdly, the above objects and advantages for the present invention are attained by a method for producing a polycarbonate which comprises polycondensing an aromatic dihydroxy compound and a carbonic acid diester in the presence of a catalyst containing a) at least one basic compound selected from the group consisting of a nitrogen-containing basic compound and a phosphorus-containing basic compound in an amount of 10 to 1,000&mgr; chemical equivalents based on 1 mol of the aromatic dihydroxy compound and b) at least one compound selected from the group consisting of an alkali metal compound and an alkali earth metal compound in an amount of 0.05 to 5&mgr; chemical equivalents based on 1 mol of the aromatic dihydroxy compound, wherein
the aromatic dihydroxy compound and the carbonic acid diester having 1) a sodium metal element content of 52 ppb or less and 2) a content of each of first elements Fe, Cr, Mn, Ni and Pb of 40 ppb or less are used, and 3) the amount of the basic compound based on 1 mol of the aromatic dihydroxy compound is not more than 20×(Fe*)+200 based on the total weight Fe* (ppb) of Fe contained in the aromatic dihydroxy compound and Fe contained in the carbonic acid diester.
THE PREFERRED EMBODIMENT OF THE INVENTION
The present invention will be described in detail hereinafter.
The aromatic polycarbonate of the present invention comprises the main recurring unit represented by the following formula (1):
wherein R
1
and R
2
are each independently an alkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, cycloalkyl group having 6 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms, cycloalkoxy group having 6 to 20 carbon atoms or aryloxy group having 6 to 20 carbon atoms, m and n are each independently an integer of 0 to 4, and X is a single bond, oxygen atom, carbonyl group, alkylene group having 1 to 20 carbon atoms, alkylidene group having 2 to 20 carbon atoms, cycloalkylene group having 6 to 20 carbon atoms, cycloalkylidene group having 6 to 20 carbon atoms, arylene group having 6 to 20 carbon atoms or alkylene-arylene-alkylene group hav
Funakoshi Wataru
Ishida Makoto
Ishihata Koji
Kageyama Yuichi
Kaneko Hiroaki
Boykin Terressa M.
Teijin Limited
LandOfFree
Aromatic polycarbonate, production method and molded... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aromatic polycarbonate, production method and molded..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aromatic polycarbonate, production method and molded... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2926555