Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Patent
1998-03-02
1999-11-09
Acquah, Samuel A.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
528491, 528492, 528493, 528494, 528495, 528496, 528502, 528503, 524 81, 524220, 524222, 524356, 524366, 524367, 428143, 428147, 428402, B32B 326
Patent
active
059810513
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for producing a granular prepolymer that is suitable as a material to be put into a polymerization reactor to be polymerized therein into polycarbonate through solid-phase polymerization.
BACKGROUND ART
For protecting the environment, many novel processes of producing polycarbonate are being developed in place of conventional interfacial polymerization using methylene chloride, and melt transesterification and solid-phase polymerization have been proposed.
Of those, solid-phase polymerization is specifically noted, as being effected at relatively low temperatures to give polycarbonate products of high quality.
It has heretofore been said that the starting polycarbonate prepolymer to be put into a polymerization reactor to be polymerized therein into polycarbonate through solid-phase polymerization is desirably a porous crystalline one having a number-average molecular weight of from 1,000 to 15,000, having a hydroxyl group and an arylcarbonate group at its terminals in a ratio of from 5/95 to 95/5, having a specific surface area of not smaller than 0.2 m.sup.2 /g, and having a degree of crystallinity of not smaller than 5 (see Unexamined Published Japanese Patent Application No. Hei-3-223330).
For producing such a porous and crystalline polycarbonate prepolymer of that type, disclosed is a method comprising introducing a solid or melt of a prepolymer as obtained through prepolymerization, into a crystallizing solvent, followed by grinding it therein under high shear into porous and crystalline prepolymer grains having an average grain size of not larger than 250.mu..
However, solid-phase polymerization using the granular prepolymer obtained in this method is problematic in that the granular prepolymer is partly fused thereby having some negative influences on the polymerization rate and making it difficult to take the polymer product out of the reactor.
Such technical troubles are peculiar to the solid-phase polymerization, and it is desired to clarify the reasons for those troubles and to solve them.
DISCLOSURE OF THE INVENTION
We, the present inventors have assiduously studied in order to solve the problems noted above, and, as a result, have found that the partial fusion of the granular prepolymer in its solid-phase polymerization would be caused by much fine powder existing in the granular prepolymer, that the solid-phase polymerization rate is often governed by the diffusion rate of phenol, and that the increase in the specific surface area of the prepolymer grains to be polymerized is effective in increasing the polymerization rate of the prepolymer. On the basis of these findings, we have developed a method for producing a granular prepolymer having an increased specific surface area and containing a reduced amount of fine powder, and have completed the present invention.
Specifically, the invention is summarized as follows:
(1) A method for producing a granular polycarbonate prepolymer for solid-phase polymerization, comprising dissolving a polycarbonate prepolymer in a solvent under heat, then cooling it to be crystallized, and thereafter shaping it to be granular.
(2) The method for producing a granular polycarbonate prepolymer for solid-phase polymerization of (1), wherein the solvent is a sole aromatic solvent or a mixture of an aromatic solvent and a poor solvent for the polycarbonate prepolymer.
(3) The method for producing a granular polycarbonate prepolymer for solid-phase polymerization of (1) or (2), wherein the concentration of the polycarbonate prepolymer in its solution is from 20 to 90% by weight.
(4) The method for producing a granular polycarbonate prepolymer for solid-phase polymerization of any of (1) to (3), wherein the hot prepolymer solution is passed through a tubular condenser to make the prepolymer crystallized therethrough, and the resulting strand is taken out and cut into pieces having a predetermined length.
(5) The method for producing a granular polycarbonate prepolymer for solid-phase polymerization of a
REFERENCES:
patent: 5204377 (1993-04-01), Fukawa et al.
Kunishi Noriyuki
Motegi Hiroaki
Shishikura Akihiro
Acquah Samuel A.
Idemitsu Petrochemical Co. Ltd.
LandOfFree
Method for producing granular polycarbonate prepolymer for solid does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing granular polycarbonate prepolymer for solid, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing granular polycarbonate prepolymer for solid will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1452952