Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-01-26
2002-06-18
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, C428S064200
Reexamination Certificate
active
06407199
ABSTRACT:
The present invention relates to a polycarbonate resin composition, an optical recording medium comprising the same and a substrate for the optical recording medium. More specifically, it relates to a novel polycarbonate resin composition which is satisfactory in terms of thermal stability such as color retention during molding and excellent in moldability such as releasability and transferability, an optical recording medium comprising the composition and a substrate for the optical recording medium.
PRIOR ARTS
Aromatic polycarbonates are widely used in various fields including optical parts, mechanical parts and auto parts, thanks to their excellent mechanical properties such as impact resistance, heat resistance and transparency.
The aromatic polycarbonates have recently been in great demand as optical moldings. owing to their excellent optical properties and widely used in optical disks, information disks, optical lenses, prisms and the like. Along with this, higher thermal stability, releasability and transferability have been required of the aromatic polycarbonates.
Since optical disks, information disks, optical lenses and the like are mainly produced by injection molding, if mold release resistance is large when these moldings are removed from a mold, they are warped, causing optical distortion. Therefore, a release agent must be used.Particularly in the production of an optical recording disk such as a compact disk (CD) or laser disk (LD), it is injection molded at a temperature higher than 300° C. to accurately transfer 1 &mgr;m or less fine irregularities of a stamper. Therefore, thermal stability is also required of a resin used in addition to releasability.
Paraffin, silicone oil, fatty acid, fatty acid esters, fatty acid partial esters and the like have been known as release agents for polycarbonate resins. Particularly, fatty acid esters, specifically partial esters of polyhydric alcohols have recently been used to improve the releasability of polycarbonate resins for optical disks.
JP-B 47-41092 (the term “JP-B” as used herein means an “examined Japanese patent publication”) discloses a lubricating polycarbonate resin composition prepared by adding 0.05 to 5 wt % of an ester or partial ester of an aliphatic saturated monocarboxylic acid having 12 to 30 carbon atoms and an aliphatic saturated monohydric alcohol or polyhydric alcohol having 30 or less carbon atoms to a polycarbonate resin.
JP-B 2-48081 discloses a polycarbonate resin composition which contains a monoglyceride of a saturated monovalent fatty acid having 16 to 22 carbon atoms in an amount of 0.01 to 0.2 part by weight based on 100 parts by weight of a polycarbonate having a viscosity average molecular weight of about 12,000 to about 19,000 and provides moldings having excellent mold transferability and an unscratched surface as well as optical moldings thereof.
JP-A 8-73724 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a polycarbonate resin composition which contains a partial ester of an aliphatic carboxylic acid and a polyhydric alcohol in an amount of 0.01 to 0.1 part by weight based on 100 parts by weight of an aromatic polycarbonate resin having a terminal hydroxyl concentration of 2 to 40 molt and a molecular weight distribution (Mw/Mn) of 2.0 to 2.8 and has excellent releasability, heat resistance and transferability.
JP-B 55-4141 discloses an antistatic polycarbonate composition which contains an aliphatic monoglyceride in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of a polycarbonate to improve the antistatic properties of the polycarbonate.
The partial ester of a saturated aliphatic monocarboxylic acid and a polyhydric alcohol disclosed by the above prior art readily thermally decomposes of itself or readily reacts with a polymer to cause thermal decomposition or ester exchange reaction. Therefore, when a conventional partial ester of a saturated monocarboxylic acid and a polyhydric alcohol is added to a polycarbonate resin, such inconvenience may occur as an increase in the amount of the residual phenol, deterioration in the quality of a molded product at the time of melt molding at a high temperature, and the formation of a silver streak as the case may be.
When other release agent, for example, a complete ester of a polyhydric alcohol is used, if the amount of the release agent is the same as that of a partial ester of a saturated aliphatic monocarboxylic acid and a polyhydric alcohol, there will be no problem with thermal stability but sufficient releasability cannot be obtained.
For the above reasons, a polycarbonate resin composition which has excellent thermal stability and releasability at the time of melt molding and a release agent satisfactory for use with the polycarbonate resin composition have been desired.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to provide a polycarbonate resin composition which solves the above problems of the prior art and has sufficient releasability and thermal stability.
It is another object of the present invention to provide a polycarbonate resin composition which is excellent in both thermal stability such as color retention, for example, prevention -of yellowing at the time of melt molding and moldability such as releasability and transferability and is suitable for the production of precision optical moldings such as optical disk substrates and lenses.
It is still another object of the present invention to provide a substrate for optical recording media made from the polycarbonate resin composition of the present invention.
It is a further object of the present invention to provide an optical recording medium comprising the substrate of the present invention.
It is a still further object of the present invention to provide a novel releasability modifier for improving the releasability of a polycarbonate resin.
It is a still further object of the present invention to provide a novel thermal yellowing inhibitor for preventing the thermal yellowing of a polycarbonate resin.
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 resin composition (may be referred to as “first composition of the present invention” hereinafter) comprising:
(A) 100 parts by weight of an aromatic polycarbonate; and
(B) 5×10
−4
to 0.5 part by weight of at least one compound selected from the group consisting of a cyclic carbonate compound represented by the following formula (1), a monoester compound of a divalent aliphatic alcohol having 3 to 14 carbon atoms and an aliphatic monocarboxylic acid having 12 to 24 carbon atoms, and an ether compound obtained by converting at least one hydroxyl group of a polyvalent. aliphatic alcohol having 2 to 14 carbon atoms into an aliphatic oxy group having 1 to 18 carbon atoms:
wherein R
1
is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R
2
and R
3
are the same or different and each a hydrogen atom or monovalent hydrocarbon group having 1 to 10 carbon atoms, and Y is a single bond, ether bond, ester bond or carbonate bond.
Secondly, the above objects and advantages. of the present invention are attained by an aromatic polycarbonate resin composition (may be referred to as “second composition of the present invention” hereinafter) comprising:
(A) 100 parts by weight of an aromatic polycarbonate:
(D) 5×10
−4
to 0.5 part by weight of a partial ester compound of an aliphatic alcohol having a valence of 2 to 6 and 2 to 14 carbon atoms and an aliphatic monocarboxylic acid having 12 to 24 carbon atoms; and
(C) 1×10
−5
to 1×10
−2
part by weight of a cyclic compound represented by the following formula (3):
wherein R
8
is a hydrogen atom or hydrocarbon group having 1 to 4 carbon atoms, and n is a number of 4 to 20, or at least one compound selected from the group con
Funakoshi Wataru
Hirata Masumi
Matsuo Jyuhou
Sasaki Katsushi
Sawaki Toru
Boykin Terressa M.
Teijin Limited
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