Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-11-08
2002-09-10
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
C428S064200, C428S066500, C528S198000
Reexamination Certificate
active
06448365
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aromatic polycarbonate composition and to an injection molded product thereof. More specifically, it relates to an aromatic polycarbonate composition having excellent transparency, color stability and residence stability during molding and to an injection molded product thereof.
PRIOR ART
A polycarbonate resin is excellent in optical properties, electric properties and dimensional stability, and has self-extinguishing properties and excellent mechanical properties such as impact resistance and rupture strength, as well as excellent heat resistance and transparency. Therefore, it is used for various purposes in large quantities. Making use of its transparency in particular, it is used in lenses, prisms, optical disks, sheets, films and the like in great quantities.
Particularly for optical resin applications such as lenses and optical disks, excellent transparency and color are required of molded products. Stated more specifically, residence stability during the molding of a resin composition, particularly thermal stability and color stability during residence, further moldability at the time of molding, that is, transferability and releasability which give precision molded products having a designed shape and size and further environmental stability such as wet heat durability are required of molded products.
To produce a molded product of a polycarbonate resin composition, a fatty acid ester-based releasing agent has been used advantageously. This releasing agent is very effective in improving releasability between a metal mold and a molded product when a precision molded product such as a disk is molded and suppresses reductions in the physical properties such as color, transparency and surface properties of a molded product. However, the fatty acid ester-based compound is characterized that it has low heat resistance and is readily thermally decomposed though it has relatively high releasability.
Particularly, a fatty acid ester-based releasing agent involves such a problem that it decomposes at a molding temperature of a polycarbonate resin, particularly a temperature higher than 340° C., in the presence of an acidic or basic compound or metal compound, thereby reducing its releasability or causing the color development of a molded product in an extreme case to contaminate a metal mold.
There are known methods of producing a polycarbonate resin: one in which phosgene is directly reacted with an aromatic dihydroxy compound (interfacial polymerization method) and one in which an ester exchange reaction between an aromatic dihydroxy compound and a diaryl carbonate such as diphenyl carbonate is carried out in a molten state (melting method).
To solve the above problem, the interfacial polymerization method succeeded in reducing impurities contained in a polycarbonate resin by making purification treatments on the resin and suppressing the decomposition of the above releasing agent by using stabilizers to a certain extent.
However, due to the recent appearance of a new standard-based DVD disk, a substrate must be molded at a high temperature of 350° C. or higher than that of the prior art and the decomposition and color development of the releasing agent or the resin composition at the time of forming the substrate are becoming new problems to be solved.
In the melting method for producing a polycarbonate through an ester exchange reaction, general ester exchange catalysts are used as disclosed by literature such as “Polycarbonate of Plastic Material Lecture 17”, pp. 48-53 to improve production efficiency. It can be said that a catalyst system in which a nitrogen-containing basic compound or a phosphorus-containing basic compound and an alkali metal compound are used in combination out of the ester exchange catalysts is preferred because it improves the productivity and color of a polycarbonate resin, suppresses the formation of a branched structure in the polymer molecule, has excellent quality such as flowability and rarely forms foreign matter such as a gel.
However, a polycarbonate resin produced by the melt polymerization method is unsatisfactory in terms of stability under a high-temperature or oxidative atmosphere or hydrolytic conditions due to its secondary reactivity derived from an alkali metal compound used as an ester exchange catalyst or additives. In addition, a releasing agent added as a precision molding aid cannot exhibit its own capability very often compared with a polycarbonate resin produced by the interfacial polymerization method or its resin composition because the releasing agent causes the above decomposition or the like.
To solve these problems, JP-A 4-328124 and JP-A 4-328156 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) propose a method of neutralizing an ester exchange catalyst with an acidic compound containing a sulfonic acid ester.
JP-A 8-59975 proposes use of a combination of a sulfonic acid phosphonium salt and a phosphorous acid ester-based compound or phenol-based antioxidant.
Further, JP-A 4-36346 discloses an aromatic polycarbonate-based resin composition which contains 100 parts by weight of an aromatic polycarbonate resin produced through an ester exchange reaction in a molten state between an aromatic organic dihydroxy compound and a carbonic acid diester in the presence of a catalytic system containing a nitrogen-containing basic compound (a) and an alkali metal compound or alkali earth metal compound (b), or a catalytic system containing (a), (b) and boric acid or boric acid ester and 0.005 to 0.5 part by weight of a phosphorus-based antioxidant.
When a precision molded product is to be produced from the above polycarbonate resin produced by the melt polymerization method using a fatty acid ester-based releasing agent, the releasing agent causes a secondary reaction such as decomposition and cannot exhibit expected parting performance to the full, thereby causing frequently such problems as the deformation of a molded product, further the color development of the molded product and the great contamination of the surface of the metal mold of a molding machine. Particularly, this tendency is marked under a high-temperature condition which is required for the molding of a DVD substrate. The above defects are very serious because they cause a transfer failure such as a groove or pit at the time of forming a precision molded product such as an optical disk.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an aromatic polycarbonate composition having excellent stability at the time of melt molding.
It is another object of the present invention to provide an aromatic polycarbonate composition which has excellent stability at the time of melt molding and suppresses decomposition and color development, a reduction in its molecular weight and the formation of black foreign matter at the time of melt molding.
It is still another object of the present invention to provide an aromatic polycarbonate composition which rarely contaminates a metal mold during molding and has excellent releasability from the metal mold.
It is a further object of the present invention to provide an aromatic polycarbonate composition which is suitable for precision molding and has excellent molding efficiency.
It is a still further object of the present invention to provide a molded product, particularly an injection molded product of the aromatic polycarbonate composition of the present invention.
Other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are attained by an aromatic polycarbonate composition comprising:
(A) 100 parts by weight of an aromatic polycarbonate
(1) which comprises mainly a recurring unit represented by the following formula (1):
wherein R
1
, R
2
, R
3
and R
4
are each independently a hydrogen atom, alkyl group having 1 to 10 carbon atoms, aryl group h
Funakoshi Wataru
Hirata Masumi
Kageyama Yuichi
Kaneko Hiroaki
Sasaki Katsushi
Boykin Terressa M.
Teijin Limited
LandOfFree
Aromatic polycarbonate composition 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 composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aromatic polycarbonate composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2862771