Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
1999-10-13
2001-06-26
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S272000
Reexamination Certificate
active
06252036
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Technical Field
This invention relates to a process for producing a polycarbonate resin. More particularly, this invention relates to a process for producing a stabilized terminal-blocked polycarbonate resin having low hydroxy terminal group content and excellent thermal stability, color stability and hydrolysis resistance by an industrially desirable method using a terminal blocking agent.
2. Background Arts
Polycarbonate resin is being used in various uses owing to its excellent mechanical properties such as impact resistance and transparency. Known processes for the production of polycarbonate resin include an interfacial process comprising the direct reaction of a dihydroxy compound with phosgene and a melt process comprising the transesterification of a dihydroxy compound with a carbonic acid diester by heating under reduced pressure.
Production of polycarbonate resin usually passes kneading a stabilizer into a polymerized polycarbonate, however, the process has a problem to deteriorate polymer qualities such as thermal stability, color stability and hydrolysis resistance when hydroxy terminal groups remain in the final product of the polycarbonate.
The specification of the Japanese Patent Laid-Open TOKKAIHEI 6-157739 discloses a process for solving the above problem by using at least two reactors in series and adding a terminal blocking agent to at least one reactor containing a polymer having an intrinsic viscosity of 0.20 dl/g or above at the inlet side of the reactor in the case of producing an aromatic polycarbonate resin by the melt-polycondensation of an aromatic dihydroxy compound with a carbonic acid diester. However, the control of the intrinsic viscosity of the final polycarbonate resin is difficult by this process owing to the decomposition of the polycarbonate caused by the reaction by-products, and a satisfiable solution is not yet found at present.
MEANS FOR SOLVING THE PROBLEMS
The object of the present invention relates to a process for producing a polycarbonate resin and is to provide an industrial process for producing a stabilized terminal-blocked polycarbonate resin having a limited number of terminal hydroxy groups and excellent thermal stability, color stability and hydrolysis resistance by blocking the terminal groups taking advantage of the reactivity of the hydroxy terminal groups of a polycarbonate and adding a stabilizer to the terminal blocked polymer.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention comprises a process for producing a polycarbonate resin characterized by adding a terminal blocking agent under reduced pressure to a polycarbonate produced by melt polycondensation of an aromatic dihydroxy compound with an aromatic carbonic acid diester in the presence of a polycondensation catalyst, kneading of the mixture thereof and then adding a stabilizer to the kneaded mixture.
A stabilized terminal-blocked polycarbonate resin having a limited number of hydroxy terminal groups on the polycarbonate with excellent thermal stability, color stability and hydrolysis resistance can be produced by the polycarbonate resin production process of the present invention.
In the present invention, the polycarbonate subjected to the terminal blocking reaction is a polymer produced by the transesterification of an aromatic dihydroxy compound with an aromatic carbonic acid diester in the presence of a polymerization catalyst in a molten state.
There is no particular restriction to the aromatic dihydroxy compound to be used in the melt polymerization, and examples of the compound are bis(hydroxyaryl)alkanes such as 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane and 1,1-bis(4-hydroxy-t-butylphenyl)propane, bis(hydroxyaryl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)cyclopentane and 1,1-bis(hydroxyphenyl)cyclohexane, dihydroxyaryl ethers such as 4,4′-dihydroxydiphenyl ether, dihydroxyaryl sulfides such as 4,4′-dihydroxydiphenyl sulfide, dihydroxyaryl sulfoxides such as 4,4′-dihydroxydiphenyl sulfoxide, and dihydroxyaryl sulfones such as 4,4′-dihydroxydiphenyl sulfone. 2,2-Bis(4-hydroxyphenyl)propane is especially preferable among the above compounds.
The aromatic carbonic acid diester to be used in the melt polymerization is an ester of an optionally substituted aryl group, aralkyl group, etc., having a carbon number of from 6 to 10. Concrete examples of the ester are diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonate, m-cresyl carbonate, dinaphthyl carbonate and bis(diphenyl)carbonate.
The amount of the above aromatic carbonic acid diester is 1.00 to 1.30 mol, preferably 1.05 to 1.10 mol based on 1 mol of the aromatic dihydroxy compound.
In a melt-polymerization process, a polymerization catalyst is used for increasing the polymerization speed in the case of producing a polycarbonate by the transesterification reaction of an aromatic dihydroxy compound with an aromatic carbonic acid diester.
The polymerization catalyst is composed of an alkali metal compound and/or an alkaline earth metal compound as a main component and, as is necessary, a nitrogen-containing basic compound as a subsidiary component.
Examples of the alkali metal compound are sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium salt, potassium salt or lithium salt of bisphenol A, sodium benzoate, potassium benzoate and lithium benzoate.
Examples of the alkaline earth metal compound are calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium bicarbonate, magnesium bicarbonate, strontium bicarbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate and strontium stearate.
Examples of the nitrogen-containing basic compound are tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylamine, triethylamine, dimethylbenzylamine and triphenylamine.
The above polymerization catalysts may be used singly or in combination.
The amount of the polymerization catalyst is selected in the range of from 1×10
−8
to 1×10
−4
equivalent, preferably from 1×10
−7
to 1×10
−4
equivalent, more preferably 1×10
−6
to 5×10
−5
equivalent in the case of an alkali metal compound and/or an alkaline earth metal compound based on 1 mol of the aromatic dihydroxy compound.
In the case of using a nitrogen-containing basic compound as a subsidiary component, its amount is selected within the range between 1×10
−5
and 1×10
−3
equivalent, preferably 1×10
−5
and 5×10
−4
equivalent based on 1 mol of the aromatic dihydroxy compound.
In the case of using an alkali metal compound and/or an alkaline earth metal compound in combination with a nitrogen-containing basic compound, the total amount of both components is 1×10
−8
to 1×10
−3
equivalent, preferably 1×10
−7
to 1×10
−3
equivalent, more preferably 1×10
−6
to 5×10
−4
equivalent based on 1 mol of the aromatic dihydroxy compound.
Other compounds may be used as cocatalysts as necessary in the melt-polymerization process. Conventional catalysts for esterification reaction and transesterification reaction such as an alkali metal or alkaline earth metal salt of boron or aluminum hydroxide, a quaternary ammonium salt, an alkali metal or alkaline earth metal alkoxide, an organic acid salt of an alkali metal or alkaline earth metal, a zinc compound, a boron c
Hatono Kazuki
Kaneko Hiroaki
Sasaki Katsushi
Sawaki Toru
Boykin Terressa M.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Teijin Limited
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