Process for producing polycarbonate and optical-disk substrate

Details Process for producing polycarbonate and optical-disk substrate Process for producing polycarbonate and optical-disk substrate

2000-06-29

2001-07-10

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

C528S198000

Reexamination Certificate

active

06258922

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a process for producing polycarbonates with well-balanced fluidity and impact resistance, and to optical-disk substrates as obtained by molding the polycarbonates produced in the process.
BACKGROUND ART
Polycarbonate resins are used for substrates for optical information-recording media on which information data are written, read or rewritten by the use of laser rays, including, for example, audio disks, laser disks, optical memory disks, magnet optical disks, etc, because the polycarbonate resins have good moldability, good transparency, good heat resistance and good mechanical properties. In particular, the substrates for DVDs (digital video disks or digital versatile disks) shall be thinner than those for ordinary CDs. Therefore, polycarbonates for substrates for DVDs are required to have good fluidity so that they could satisfy the requirements of reduced birefringence, good transcriptional ability and good cracking resistance in molding. To increase their fluidity, polycarbonates may be so controlled as to have a lowered molecular weight. However, the problem with polycarbonates having a lowered molecular weight is that their impact resistance is poor. Therefore, polycarbonates for DVD substrates are required to have well-balanced and improved fluidity and impact resistance.
For producing polycarbonates, known are a method of directly reacting a dihydroxy compound such as a diphenol or the like with phosgene (interfacial polycondensation), and a method of transesterifying a dicarbonate with a dihydroxy compound such as a diphenol or the like in a melt phase (melt polymerization). We, the present inventors have proposed DVD substrates produced through interfacial polycondensation (see Japanese Patent Laid-Open No. 276037/1990).
However, the DVD substrates proposed are problematic in that the interfacial polycondensationmethod for them requires toxic phosgene as one reactant and is therefore unfavorable. In addition, although their properties are good in some degree, they are not yet on the satisfactory level.
One object of the present invention is to provide a process for producing polycarbonates having well-balanced fluidity and impact resistance, without requiring toxic phosgene as the reactant. Another object of the invention is to provide optical-disk substrates with reduced birefringence and improved transcriptional ability, by molding the polycarbonates produced in the process.
DISCLOSURE OF THE INVENTION
We, the present inventors have found that, when a dicarbonate is transesterified with a dihydroxy compound to produce a polycarbonate in the presence of a chain terminator having a specific structure, then the polycarbonate produced can have well-balanced fluidity and impact resistance. On the basis of this finding, we have completed the invention.
Specifically, the invention provides a process for producing polycarbonates, and optical-disk substrates, which are as follows:
1. A process for producing a polycarbonate, which comprises transesterifying a dicarbonate with a dihydroxy compound in the presence of a compound having a structure of the following general formula (1) and serving as a chain terminator:
wherein X represents —OH, —COOH, —COCl or —NH
2
; R represents an alkyl group having a branched structure with from 5 to 20 carbon atoms; and n indicates an integer of from 1 to 5.
2. The process for producing a polycarbonate of above 1, wherein the transesterification of a dicarbonate with a dihydroxy compound is effected in the presence of at least one catalyst selected from the group consisting of nitrogen-containing organic basic compounds and phosphorus-containing basic compounds.
3. A process for producing a polycarbonate, which comprises preparing a polycarbonate prepolymer through prepolymerization of a dihydroxy compound with a dicarbonate followed by polymerizing the resulting prepolymer in a solid phase or in a swollen solid phase in the presence of a compound having a structure of the following general formula (1) and serving as a chain terminator:
wherein X represents —OH, —COOH, —COCl or —NH
2
; R represents an alkyl group having a branched structure with from 5 to 20 carbon atoms; and n indicates an integer of from 1 to 5.
4. The process for producing a polycarbonate of above 3, wherein the prepolymerization of a dihydroxy compound with a dicarbonate to give a polycarbonate prepolymer followed by the polymerization of the resulting prepolymer in a solid phase or in a swollen solid phase is effected in the presence of at least one catalyst selected from the group consisting of nitrogen-containing organic basic compounds and phosphorus-containing basic compounds.
5. The process for producing a polycarbonate of above 2 or 4, wherein the phosphorus-containing basic compounds are quaternary phosphonium salts.
6. An optical-disk substrate as produced by molding the polycarbonate prepared in the process of any one of above 1 to 5.
7. The optical-disk substrate of above 6, which is for DVDs (digital video disks or digital versatile disks).
BEST MODES OF CARRYING OUT THE INVENTION
The invention is described in detail hereinunder.
1. Process for Producing Polycarbonates:
(1) Starting Materials:
(A) Dihydroxy Compounds:
For example, aromatic dihydroxy compounds and aliphatic dihydroxy compounds are mentioned, and at least one selected from them is used in the invention.
As examples of the aromatic dihydroxy compounds usable as the component (A), mentioned are those of a general formula (2):
In formula (2), R
l
and R
2
each represent a halogen atom such as a fluorine, chlorine, bromine or iodine atom, or an alkyl group having from 1 to 8 carbon atoms such as a methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl, cyclohexyl, heptyl or octyl group. R
1
and R
2
may be the same or different ones. Plural R
1
's, if any, may be the same or different ones; and plural R
2
's, if any, may be the same or different ones. m and n each represent an integer of from 0 to 4. Z represents a single bond, an alkylene group having from 1 to 8 carbon atoms, an alkylidene group having from 2 to 8 carbon atoms, a cycloalkylene group having from 5 to 15 carbon atoms, a cycloalkylidene group having from 5 to 15 carbon atoms, or a bond of —S—, —SO—, —SO
2
—, —O— or —CO—, or a bond of the following formula (3) or (4):
The alkylene group having from 1 to 8 carbon atoms and the alkylidene group having from 2 to 8 carbon atoms include, for example, methylene, ethylene, propylene, butylene, pentylene, hexylene, ethylidene and isopropylidene groups. The cycloalkylene group having from 5 to 15 carbon atoms and the cycloalkylidene group having from 5 to 15 carbon atoms include, for example, cyclopentylene, cyclohexylene, cyclopentylidene and cyclohexylidene groups.
Concretely, the compounds include hydroquinone, 4,4′-dihydroxydiphenyl, bis(4-hydroxyphenyl)alkanes, bis(4-hydroxyphenyl)cycloalkanes, bis(4-hydroxyphenyl) oxide, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl) sulfone, bis(4-hydroxyphenyl) ketone, 9,9-bis(4-hydroxyphenyl)fluorene and their halide derivatives. Of those, preferred is 2,2-bis(4-hydroxyphenyl)propane (bisphenol A). One or more of the compounds mentioned above are suitably selected and used as the dihydroxy compounds for the component (A).
(B) Dicarbonates:
Various types of dicarbonates are usable in the invention. For example, used is at least one selected from the group consisting of diaryl carbonates, dialkyl carbonates and alkylaryl carbonates.
The diaryl carbonates usable for the component (B) include compounds of a general formula (5):
wherein Ar
1
and Ar
2
each represent an aryl group, and these may be the same or different ones;
and compounds of a general formula (6):
wherein Ar
3
and Ar
4
each represent an aryl group, and these may be the same or different ones; and D
1
represents a residue of an aromatic dihydroxy compound of those noted above from which two hydroxyl groups are removed.
The dialkyl carbonates include compounds of a general f

Affiliated with

Also associated with

Rating

Process for producing polycarbonate and optical-disk substrate does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for producing polycarbonate and optical-disk substrate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing polycarbonate and optical-disk substrate will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2543229