Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-06-18
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
06355768
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polycarbonate resin with transparency, heat resistance, a low photoelastic constant and impact resistance and a process for producing the same. The polycarbonate resin is suitably applicable to materials of plastic optical products such as optical disc substrates, various lenses, prisms and optical fibers.
BACKGROUND ART
A polycarbonate resin from 2,2-bis(4-hydroxy-phenyl) propane (so-called bisphenol A) obtained by reaction of bisphenol A with phosgene or carbonic acid diester is applied widely to not only structural materials, but also optical materials such as optical disc substrates, various lenses, prisms and optical fibers, since it has excellent heat resistance, excellent transparency and furthermore excellent mechanical properties such as impact resistance.
However, the polycarbonate resin made from bisphenol A has a problem in which double refraction becomes large due to molecular orientation and residual stress during molding, since it is a material with a high photoelastic constant and a low flowability. Thus, when an optical material composed of the polycarbonate resin made from bisphenol A is molded, a method for lowering double refraction of its product by molding at a high temperature using a polycarbonate resin with comparatively low molecular weight has been applied. However, since there is a limit for lowering double refraction of the polycarbonate resin produced from bisphenol A, even when the above-mentioned method is applied, a material with further low photoelastic constant and high flowability has been earnestly required in a partial field of optical material, particularly in the field of optical disc with recent expansion of use of optical material.
As a method for lowering a photoelastic constant of a polycarbonate resin, for example, as shown in Japanese Patent Kokai (Laid-open) No.64-66234, copolymerizing bisphenol A with tricyclo (5.2.1.0
2,6
) decane dimethanol is known. However, this method causes deterioration of heat resistance and does not provide sufficient effects in lowering photoelastic constant.
Further, as disclosed in Japanese Patent Kokai (Laid-open) Nos. 6-25398 and 7-109342, processes for copolymerizing bisphenols having a fluorene structure on side chains with other bisphenols are known, but these processes have problems that a glass transition point becomes high and furthermore flowability during melting is low, so that it is difficult to form a thin molded article such as an optical disc substrate since bisphenols containing a fluorene structure are used in a high proportion in order to lower a photoelastic constant.
DISCLOSURE OF THE INVENTION
An object of the present invention is to solve above-mentioned prior art problems and provide a polycarbonate resin which has a lower photoelastic constant than a polycarbonate resin from bisphenol A and a process for producing the same.
As a result of extensive studies to solve above-mentioned prior art problems, the inventors have found that the problems can be solved by providing a polycarbonate resin consisting essentially of structural units of the structure formula (1) and the structure formula (2) wherein a molar ratio of the structure formula (1)/structure formula (2) is 70/30 to 5/95, and have accomplished the present invention.
That is, the present invention provides a polycarbonate resin consisting essentially of structural units of the structure formula (1) and the structure formula (2), wherein a molar ratio of the structure formula (1)/the structure formula (2) is 70/30 to 5/95.
wherein R
1
and R
2
are, each independently, hydrogen atom, halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, an cycloalkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a cycloalkoxyl group having 6 to 20 carbon atoms or an aryloxy group having 6 to 20 carbon atoms and m and n are an integer of 0 to 4.
wherein W is an cycloalkylene group having 6 to 20 carbon atoms and 1 to 4 cyclo rings.
The present invention provides also a polycarbonate resin consisting essentially of structural units represented by the above-mentioned structure formula (1) and structure formula (2) and a structural unit represented by the structure formula (3), wherein a molar ratio (3)/[(1)+(2)] of the structure unit represented by the structure formula (3)/the structural units represented by the structure formula (1) and the structure formula (2) is 50/50 to 10/90.
wherein X is:
R
5
and R
6
are, each independently, hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; a combination of R
5
and R
6
may form a ring; R
3
and R
4
are, each independently, hydrogen atom, halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms; a cycloalkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a cycloalkoxyl group having 6 to 20 carbon atoms or an aryloxy group having 6 to 20 carbon atoms and p and q are an integer of 0 to 4.
Further the present invention provides a process for producing above-mentioned polycarbonate resin.
The polycarbonate resin of the present invention will be described in detail below.
The polycarbonate resin of the present invention is obtained by polycondensation of structural units derived from an aromatic dihydroxy compound represented by the general formula (4) and an aliphatic dihydroxy compound represented by the general formula (5) and a carbonic acid diester.
wherein R
1
and R
2
are, each independently, hydrogen atom, halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, a cycloalkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a cycloalkoxyl group having 6 to 20 carbon atoms or an aryloxy having 6 to 20 carbon atoms and m and n are an integer of 0 to 4.
HO—CH
2
—W—CH
2
—OH (5)
wherein W is a cycloalkylene group having 6 to 20 carbon atoms and 1 to 4 cyclo rings.
Examples of aromatic dihydroxy compound represented by the general formula (4) include 9,9-bis(4-hydroxyphenyl) fluorene, 9,9-bis(4-hydroxy-3-methylphenyl) fluorene and 9,9-bis(4-hydroxy-3-ethylphenyl) fluorene.
Examples of aliphatic dihydroxy compound represented by the general formula (5) include cyclohexane-1,4-dimethanol, norbornane dimethanol, tricyclo(5.2.1.0
2,6
) decane dimethanol and decalin-2,6-dimethanol.
A molar ratio (1)/(2) of structural unit(1) derived from the aromatic dihydroxy compound represented by the general formula (4) to structural unit (2) derived from the aliphatic dihydroxy compound represented by the general formula (5) is usually 70/30 to 5/95, preferably 70/30 to 10/90 and more preferably 70/30 to 20/80. That is, when a molar ratio (1)/(2) of structural unit (1) derived from the aromatic dihydroxy compound represented by the general formula (4) to structural unit (2) derived from the aliphatic dihydroxy compound in a polycarbonate resin is above 70/30, a glass transition temperature becomes high, so that it is not preferable since flowability during molding is deteriorated. Further, when it is below 5/95, a glass transition temperature becomes low, so that it is not preferable since it becomes difficult to use practically it due to deterioration of heat resistance.
In the polycarbonate resin of the present invention, it is preferable from the viewpoint of property balance to introduce a structural unit of an aromatic dihydroxy compound represented by the below general formula (6) in addition to a structural unit derived the aromatic dihydroxy compound represented by the above-mentioned general formula (4), a structural unit derived from the aliphatic dihydroxy compound represented by the above-mentioned general formula (5) and a structural unit derived from carbonic acid diester.
wherein X is:
R
5
and R
6
are, each independently, hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; a combin
Fujimori Takayasu
Hirata Masukazu
Boykin Terressa M.
Mitsubishi Gas Chemical Company Inc.
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