A method for manufacturing polycarbonate by melt-polycondensing bisphenol and carbonic acid diester uses as catalyst an alkali metal compound and/or alkaline earth metal compound (a). The catalyst is added to the bisphenol prior to the melt polycondensation, in an effective amount, i.e., the amount of alkali metal compound and/or alkaline earth metal compound (a) that acts effectively as a catalyst, is contained in said bisphenol, and is controlled to have the same catalytic activity as 1×10
−8
to 1×10
−6
mole of bisphenol disodium salt per mole of pure bisphenol A. The method conducts the reaction efficiently from the initial stage in a stable manner to obtain polycarbonate with good color, good heat stability and color stability during molding and the like.
According to the present invention, there is provided an improvement which comprises adding an acid compound and if necessary an epoxy compound to a reaction product resulting from melt polycondensation reaction of an aromatic dihydroxy compound with a carbonic acid diester in the presence of an alkaline compound catalyst.
A method for preparing polycarbonates, which method is characterized by inducing the melt polycondensation of an aromatic dihydroxy compound and a diester carbonate in the presence of a total amount in the reaction system of 5x10-8 to 8x10-7 mole of alkali metal compounds and/or alkaline earth metal compounds per mole of the aromatic dihydroxy compound, and adding to the polycarbonate which is the reaction product thereof; a sulfonic acid compound having formula (III) below in an amount of 0.05-10 ppm, based on the polycarbonate
where R7 is a hydrocarbon group having 1-6 carbons (in which the hydrogens may be substituted with halogens), R8 is a hydrocarbon group with 1-8 carbons (in which the hydrogens may be substituted with halogens), and n is an integer from 0 to 3.
An optical polycarbonate composition is obtained by :
formulating
[B] a boron compound in an amount of 0.00001-0.2 part by weight per 100 parts by weight of
[A] a polycarbonate resin having an intrinsic viscosity of 0.30-0.65 dL/g, as measured in 20°C methylene chloride;
or by replacing [B] by, or by adding to [A] and [B], an acid compound having a pKa value of 3 or less and/or a derivative formed from said compound in an amount of 0.00001-0.0005 part by weight.
The acid compound may be a sulfonic acid compound. Other substances may also be added.
Polycarbonate resin compositions containing A) 100 wt. parts polycarbonates, and B) 0.001∼5 wt. parts esters of aliphatic carboxylic acids and alcohols, in which the polycarbonates are products of melt polymerization of aromatic dihydroxy compounds with carbonate diesters, are provided. These resin compositions are characterized by good mold release and thermal stability, and very little discoloration during molding.
提供了含有 A) 100 重量份聚碳酸酯和 B) 0.001∼5 重量份脂肪族羧酸和醇酯的聚碳酸酯树脂组合物,其中聚碳酸酯是芳香族二羟基化合物与碳酸酯二酯熔融聚合的产物。这些树脂组合物具有良好的脱模性和热稳定性,在成型过程中很少变色。