Method for preparing a polycarbonate oligomer mixture at low temperature for manufacturing polycarbonate

A method for preparing polycarbonate, comprising the steps of:

• (i) preparing a polycarbonate oligomer mixture comprising the steps of:
• (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises,
• i. a melted activated diaryl carbonate composition, and
• ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers,
• (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system,
• (c) maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting point of the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and
• (d) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture, and
• (ii) introducing the polycarbonate oligomer mixture from step (i) to a polycondensation system to build molecular weight, thereby producing polycarbonate.

A molded article formed from polycarbonate produced by the method, comprising the steps of:

• (i) preparing a polycarbonate oligomer mixture comprising the steps of:
• (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises,
• i. a melted activated diaryl carbonate composition, and
• ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers,
• (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system,
• (c) maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting points of the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and
• (d) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture, and
• (ii) introducing the polycarbonate oligomer mixture from step (i) to a polycondensation system to build molecular weight, thereby producing polycarbonate, and
• (iii) forming a molded article from the polycarbonate.

A method for making a molded article formed from polycarbonate produced by the method, comprising the steps of:

• (i) preparing a polycarbonate oligomer mixture comprising the steps of:
• (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises,
• i. a melted activated diaryl carbonate composition, and
• ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers,
• (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system,
• (c) maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting point of the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and
• (d) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture, and
• (ii) introducing the polycarbonate oligomer mixture from step (a) to a polycondensation system to build molecular weight, thereby producing polycarbonate, and
• (iii) forming a molded article from the polycarbonate.

An apparatus for making polycarbonate comprising:

• (a) one or more melters containing either separately or in combination an activated diaryl carbonate composition and a dihydroxy composition;
• (b) a equilibration vessel connected to the one or more melters and receiving melted activated diaryl carbonate composition and melted dihydroxy composition therefrom via one or more monomer feed lines;
• (c) a feed line connected to the equilibration vessel and containing a polymerization catalyst;
• (d) a polycondensation system, wherein the polycondensation system is connected at one end to the equilibration vessel;
• and
• (e) a transfer line connecting the equilibration vessel to the polycondensation system and containing an oligomer stream;
• wherein the equilibration vessel has a size and the apparatus has a flow rate that are selected in combination such that the residence time of the activated diaryl carbonate composition and the dihydroxy composition in the equilibration vessel is sufficient to produce polycarbonate oligomers within the equilibration vessel.

A method of preparing a polycarbonate oligomer mixture comprising the steps of:

• (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises,
• i. a melted activated diaryl carbonate composition, and
• ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers,
• (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system, wherein the dihydroxy composition is selected from the group consisting of 2,6-dihydroxy naphthalene;
• 2,6-dihydroxy-3-methyl naphthalene;
• and 2,6-dihydroxy-3-phenyl naphthalene, and
• (c) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture, wherein the melted dihydroxy compound is provided from a melting apparatus, and wherein the dihydroxy compound has a total residence time in the melting apparatus and the equilibration system such that the polycarbonate oligomer mixture has a Yellowness Index (YI) of less than 10.