Method of crystallizing low-molecular polycarbonate and process for producing polycarbonate resin from the same

A polycarbonate, low-molecular-weight technology for the production of high-molecular-weight polycarbonates with excellent color tone with less gel content

Inactive Publication Date: 2002-10-23
TEIJIN LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The object of the present invention is to solve the above-mentioned problems caused by the conventional methods and to provide a method for effectively crystallizing low-molecular-weight aromatic polycarbonate in an uncrystallized state and a method for efficiently producing polycarbonate resins using the crystallization method Methods

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0112]228 parts by weight of 2,2-bis(hydroxyphenyl)propane, 223 parts by weight of diphenyl carbonate, 0.009 parts by weight of tetramethyl Ammonium hydroxide and 0.00014 parts by weight of bisphenol A disodium salt were dissolved by stirring the mixture at 180° C. for 30 minutes under nitrogen. Subsequently, the pressure was gradually lowered while the temperature was raised, and they were reacted while the phenol produced was distilled off until the final state of 220° C. and 30 mmHg was reached. The low molecular weight polycarbonate (oligomer) obtained at this time had an intrinsic viscosity [η] of 0.015 and a glass transition temperature (Tg) of 116°C. Reference Example 2: Synthesis Example of Crystallized Aromatic Polycarbonate

Embodiment 2

[0112]228 parts by weight of 2,2-bis(hydroxyphenyl)propane, 223 parts by weight of diphenyl carbonate, 0.009 parts by weight of tetramethyl Ammonium hydroxide and 0.00014 parts by weight of bisphenol A disodium salt were dissolved by stirring the mixture at 180° C. for 30 minutes under nitrogen. Subsequently, the pressure was gradually lowered while the temperature was raised, and they were reacted while the phenol produced was distilled off until the final state of 220° C. and 30 mmHg was reached. The low molecular weight polycarbonate (oligomer) obtained at this time had an intrinsic viscosity [η] of 0.015 and a glass transition temperature (Tg) of 116°C. Reference Example 2: Synthesis Example of Crystallized Aromatic Polycarbonate

[0113] A part of the low-molecular-weight polycarbonate (oligomer) obtained in the above-mentioned Reference Example 1 was taken out and subjected to heat treatment at 180° C. for 4 hours in a nitrogen atmosphere. During the 1 hour heat treatm...

Embodiment 3

[0119] By using a twin-screw extruder, 475 parts by weight of the low-molecular-weight polycarbonate obtained in the above-mentioned Reference Example 1 and 25 parts by weight of the crystalline polycarbonate powder obtained in Reference Example 2 were melt-mixed, and then Extrude at 220°C, and dip the extruded product in a phenol bath heated at 60°C for 5 minutes after cutting. After impregnation, the phenol was removed by filtration and the polymer was dried at 90°C for 1 hour to obtain a crystalline product with a particle size of 0.6-1.4 mm. The resulting crystalline product was further heated at 180°C for 1 hour to promote crystallization. The crystalline product had an intrinsic viscosity [η] of 0.25, a melting point of 240.2°C, a ΔH of 47.5 J / g, and a crystallinity of 23%, during which generation of fine particles was hardly detectable.

[0120] By using the obtained polycarbonate, solid phase polymerization was carried out at 220°C for 10 hours in the same manner as i...

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Abstract

A method of efficiently crystallizing a low molecular weight aromatic polycarbonate; and a method of producing a polycarbonate resin having a desired intrinsic viscosity from the polycarbonate obtained by the crystallization method. A low molecular weight aromatic polycarbonate, preferably produced by melt polycondensation, is contacted with an aromatic monohydroxy compound or a mixture of said compound and water to crystallize the polycarbonate. Alternatively, the low-molecular-weight aromatic polycarbonate is melt-mixed with at least one compound selected from aromatic monohydroxy compounds, carbonic acid diester compounds, and aromatic dihydroxy compounds to crystallize the polycarbonate. Crystallized polycarbonate is polymerized to a higher degree by heating it at a temperature below its melting point under reduced pressure or in an inert gas stream. A polycarbonate resin having a desired intrinsic viscosity is thereby produced.

Description

technical field [0001] The present invention relates to the crystallization of low molecular weight polycarbonates and a method for preparing polycarbonate resins using the crystallization method. More specifically, the present invention relates to a crystallization method in which the engineering design of the recovery method is simple and short-time crystallization is easy, and a high-productivity product having an excellent color tone accompanied by less gel components by using the crystallization method. Molecular weight polycarbonate method. Background of the invention [0002] Aromatic polycarbonates are materials excellent in transparency, heat resistance, and mechanical properties, and are currently used in optical applications such as CDs (Compact Discs), optical discs, or lenses, and they are used as engineering plastics in the automotive field, electrician and Various fields such as electronic applications and various containers. [0003] Such aromatic polycarbo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G64/20C08G64/40
CPCC08G64/20C08G64/40
Inventor 樱井智德城户伸明松村俊一石渡丰明河野一辉铃木启高芳贺宏典彦坂彻
Owner TEIJIN LTD
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