Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-04-28
2002-03-12
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
06355766
ABSTRACT:
TECHNICAL FIELD
The present invention relates to polycarbonate compositions, and especially relates to polycarbonate compositions for use in data storage media.
BACKGROUND OF THE INVENTION
Optical, magnetic and magneto-optic media are primary sources of high performance storage technology which enables high storage capacity coupled with a reasonable price per megabyte of storage. Areal density, typically expressed as billions of bits per square inch of disk surface area (gigabits per square inch (Gbits/in
2
)), is equivalent to the linear density (bits of information per inch of track) multiplied by the track density in tracks per inch. Improved areal density has been one of the key factors in the price reduction per megabyte, and further increases in areal density continue to be demanded by the industry.
In the area of optical storage, advances focus on access time, system volume, and competitive costing. Increasing areal density is being addressed by focusing on the diffraction limits of optics (using near-field optics), investigating three dimensional storage, investigating potential holographic recording methods and other techniques.
Polycarbonate data storage media has been employed in areas such as compact disks (CD) and recordable compact discs (e.g., CD-RW), and similar relatively low areal density devices, e.g. less than about 1 Gbits/in
2
, which are typically read-through devices requiring the employment of a good optical quality substrate having low birefringence, heat resistance, and moldability. Next generation storage media, however, are anticipated to possess more stringent specifications and tolerances on pit/groove replication, birefringence, and dimensional stability.
What is needed in the art are advances in polycarbonate compositions and/or moldabiltiy to birefringence, dimensional stability, and replications.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a polycarbonate composition and a data storage media using the same. The polycarbonate composition comprises, based upon 100 pbw: about 50 to about 96 pbw of polycarbonate resin (A) having a weight average molecular weight (M
w
) of about 14,000 atomic mass units (AMU) to about 40,000 AMU; about 4 pbw to about 30 pbw of polycarbonate resin (B) having a M
w
of about 1,000 AMU to about 10,000 AMU; and 0 to about 20 pbw of polycarbonate resin (C) having a M
w
of greater than about 23,000 AMU.
The data storage media comprises: a polycarbonate substrate comprising, based upon 100 pbw: about 50 to about 96 pbw of polycarbonate resin (A) having a M
w
of about 12,000 AMU to about 40,000 AMU, about 4 pbw to about 30 pbw of polycarbonate resin (B) having a M
w
of about 1,000 AMU to about 14,000 AMU; and about 0 to about 20 pbw of polycarbonate resin (C) having a M
w
of greater than about 23,000 AMU; and a data storage layer disposed on at least one side of said substrate.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a polycarbonate composition and a storage media substrate comprising the same. The polycarbonate composition comprises, based upon 100 parts by weight (pbw): about 50 to about 96 pbw polycarbonate resin (A), with about 75 to about 96 pbw preferred, and about 84 to about 92 pbw most preferred, wherein polycarbonate resin (A) has a weight average molecular weight (M
w
) of about 12,000 AMU to about 40,000 AMU, with about 14,000 AMU to about 20,000 AMU preferred; about 4 pbw to about 30 pbw of polycarbonate resin (B), with about 4 to about 15 pbw preferred, and about 8 pbw to about 12 pbw especially preferred, wherein polycarbonate resin (B) has a M
w
of about 1,000 AMU to about 14,000 AMU, with about 5,000 AMU to about 10,000 AMU preferred; and 0 to about 20 pbw of polycarbonate resin (C), with about 0.05 to about 10 pbw preferred, and about 0.1 to about 4 pbw especially preferred, wherein polycarbonate resin (C) has a M
w
of greater than about 23,000 AMU, with about 23,000 AMU to about 125,000 AMU preferred.
As used herein, the terms “polycarbonate”, “polycarbonate composition”, and “composition comprising aromatic carbonate chain units” includes compositions having structural units of the formula (I):
in which at least about 60 percent of the total number of R
1
groups are aromatic organic radicals and the balance thereof are aliphatic, alicyclic, or aromatic radicals. Preferably, R
1
is an aromatic organic radical and, more preferably, a radical of the formula (II):
—A
1
—Y
1
—A
2
— (II)
wherein each of A
1
and A
2
is a monocyclic divalent aryl radical and Y
1
is a bridging radical having one or two atoms which separate A
1
from A
2
. In an exemplary embodiment, one atom separates A
1
from A
2
. Illustrative, non-limiting examples of radicals of this type are —O—, —S—, —S(O)—, —S(O
2
)—, —C(O)—, methylene, cyclohexyl-methylene, 2-[2,2,1]-bicycloheptylidene, ethylidene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene, cyclododecylidene, and adamantylidene. The bridging radical Y
1
can be a hydrocarbon group or a saturated hydrocarbon group such as methylene, cyclohexylidene or isopropylidene.
Polycarbonates can be produced by the interfacial reaction of dihydroxy compounds in which only one atom separates A
1
and A
2
. As used herein, the term “dihydroxy compound” includes, for example, bisphenol compounds having general formula (III) as follows:
wherein R
a
and R
b
each represent a halogen atom or a monovalent hydrocarbon group and may be the same or different; p and q are each independently integers from 0 to 4; and X
a
represents one of the groups of formula (IV):
wherein R
c
and R
d
each independently represent a hydrogen atom or a monovalent linear or cyclic hydrocarbon group and R
e
is a divalent hydrocarbon group.
Some illustrative, non-limiting examples of suitable dihydroxy compounds include the dihydroxy-substituted aromatic hydrocarbons disclosed by name or formula (generic or specific) in U.S. Pat. No. 4,217,438, which is incorporated herein by reference. A nonexclusive list of specific examples of the types of bisphenol compounds that may be represented by formula (III) includes the following: 1,1-bis(4-hydroxyphenyl)methane; 1,1-bis(4-hydroxyphenyl)ethane; 2,2-bis(4-hydroxyphenyl)propane (hereinafter “bisphenol A” or “BPA”); 2,2-bis(4-hydroxyphenyl)butane; 2,2-bis(4-hydroxyphenyl)octane; 1,1-bis(4-hydroxyphenyl)propane; 1,1-bis(4-hydroxyphenyl)n-butane; bis(4-hydroxyphenyl)phenylmethane; 2,2-bis(4-hydroxy-1-methylphenyl)propane; 1,1-bis(4-hydroxy-t-butylphenyl)propane; bis(hydroxyaryl)alkanes such as 2,2-bis(4-hydroxy-3-bromophenyl)propane; 1,1-bis(4-hydroxyphenyl)cyclopentane; and bis(hydroxyaryl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)cyclohexane; and the like as well as combinations comprising at least one of the foregoing. Preferred polycarbonates are based on bisphenol A, in which each of A
1
and A
2
is p-phenylene and Y
1
is isopropylidene.
In addition to the polycarbonate, the composition may optionally include various additives ordinarily incorporated in resin compositions of this type. Such additives may include antioxidants, heat stabilizers, antistatic agents, mold releasing agents (pentaerythritol tetrastearate; glycerol monstearate, and the like), and the like, and combinations comprising at least one of the foregoing. For example, about 0.01 to about 0.1 pbw of a heat stabilizer; about 0.01 to about 0.2 pbw of an antistatic agent; about 0.1 to about 1 pbw of a mold releasing agent. The above amounts of the additives are based on 100 pbw of the polycarbonate resin.
Some possible antioxidants include, for example, organophosphites, for example, tris(nonyl-phenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite and the like; alkylated monophenols, polyphenols and alkylated reaction products of polyphenols with dienes, such as, for example, tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, 3,5-di-tert-butyl-4-hydroxyhydrocinnamate octadecyl,
Boykin Terressa M.
General Electric Company
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