Polycarbonate resin and process for producing the same

Details Polycarbonate resin and process for producing the same Polycarbonate resin and process for producing the same

2000-01-04

2001-11-13

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

06316576

ABSTRACT:

BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to a polycarbonate resin with transparency, heat resistance, a low photoelastic constant and a good property balance between refractive index and Abbe's number, which is suitably applicable to plastic optical products including optical disc substrates, various lenses, prisms and optical fibers and a process for producing the same.
2) Prior Art
Polycarbonate resin from 2,2-bis(4-hydroxyphenyl)propane (the so-called bisphenol A) obtainable by reaction of bisphenol A with phosgene or carbonic acid diester is applied in a wide range to structure materials and optical disc substrates, various lenses, prisms and optical fibers as optical materials since it has excellent heat resistance, transparency and furthermore excellent mechanical properties such as impact resistance.
However, the polycarbonate resin from bisphenol A causes a problem in which double refraction becomes large due to molecular orientation or residual stress during molding since it is a material with low flowability and has a high photoelastic constant. Thus, when an optical material composed of the polycarbonate resin 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 in the above-mentioned method, 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, a method for copolymerizing bisphenol A with tricyclo (5.2.1.0
2·6
)decane dimethanol is known. However, the method causes deterioration of heat resistance and does not provide sufficient effects in lowering of photoelastic constant.
Further, as lens materials, particularly a spectacle lens material, CR-39 (diethyleneglycol bisarylcarbonate) has been widely used, but it causes a problem of low productivity since it is a thermosetting resin with a low refractive index of 1.50. Thus, it has been desired to solve such problem.
SUMMARY OF THE INVENTION
An object of the present invention is to solve above-mentioned prior art problems and provide a polycarbonate resin having a lower photoelastic constant than a polycarbonate resin from bisphenol A and a good balance between refractive index and Abbe's number 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 derived from pentacyclopentadecanedimethanol, and has accomplished the present invention.
That is, the present invention provides a polycarbonate resin obtainable by reaction of pentacyclopentadecanedimethanol with carbonic acid diester.
The present invention provides also a polycarbonate resin obtainable by reaction of pentacyclopentadecanedimethanol, an aromatic dihydroxy compound represented by the general formula (1) and carbonic acid diester.
wherein each R
1
and R
2
, independently, is a hydrogen atom, a 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 represent the number of substituent which is an integer of 0 to 4, and X is:
and each R
3
and R
4
, independently, is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 20 carbon atoms and R
5
and R
6
, independently, is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and n is an integer of 4 to 9.
DETAILED DESCRIPTION OF THE INVENTION
The polycarbonate resin of the present invention is obtained by pentacyclopentadecanedimethanol (hereinafter, referred to as “PCPDM”) and carbonic acid diester.
PCPDM is a compound(s) represented by the following formulas (2) and/or (3) and may be a single substance and a mixture of each isomer thereof in an optional ratio.
It is preferable from the viewpoint of property balance to introduce an aromatic dihydroxy compound represented by the following general formula(1) (hereinafter, referred to as “aromatic dihydroxy compound) as a reactant in addition to PCPDM and carbonic acid diester.
wherein each R
1
and R
2
, independently, is a hydrogen atom, a 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 represent the number of substituent which is an integer of 0 to 4, and X is:
and each R
3
and R
4
, independently, is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 20 carbon atoms and R
5
and R
6
, independently, is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and n is an integer of 4 to 9.
The molar ratio of the aromatic hydroxy compound/PCPDM is 0/100 to 70/30 and preferably 5/95 to 60/40. When the molar ratio of the aromatic hydroxy compound/PCPDM is above 70/30, it is not preferable since the photoelastic constant of the polycarbonate resin becomes large and furthermore the balance between refractive index and Abbe's number becomes bad.
In the polycarbonate resin of the present invention, it is possible to improve impact strength by containing the aromatic dihydroxy compound as a reactant. That is, it is preferable that the molar ratio of the aromatic hydroxy compound/PCPDM is 30/70 to 70/30 from the viewpoint of impact strength. When the molar ratio is below 30/70, effects for impact strength becomes small.
Examples of the aromatic dihydroxy compound include bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, 1,1-bis (4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydroxy-3-tert-butylphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-phenylphenyl)propane,2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane,1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxy-3-methoxyphenyl)propane, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 4,4′-dihydroxydiphenylether, 4,4′-dihydroxy-3,3′-dimethyldiphenylether, 4,4′-dihydroxyphenyl sulfide, 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfide, 4,4′-dihydroxydiphenyl sulfoxide, 4,4′-dihydroxy-3,3′-dimethyl diphenyl sulfoxide, 4,4′-dihydroxy diphenyl sulfone and 4,4′-dihydroxy-3,3′-dimethyl diphenyl sulfone.
As the aromatic dihydroxy compound, particularly 2,2-bis(4-hydroxyphenyl)propane(the so-called bisphenol A) is suitably used. Bisphenol A is very useful since it has been produced in a large amount in a low price as a raw material of polycarbonate resin and use of bisphenol A makes possible increase of impact resistance without impairing heat resistance.
In the present invention, other species of dihydroxy compound than the aromatic dihydroxy compound represented by the general formula (1) may be copolymerized with PCPDM, the aromatic hydroxy compound and carbonic acid diester in the range not to impair various properties. Examples of other species of dihydroxy compound include tricyclo

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