Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2002-05-02
2004-03-23
Boykin, Terressa (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C525S461000, C525S462000, C525S463000, C528S198000, C528S199000
Reexamination Certificate
active
06710152
ABSTRACT:
The present invention relates to solid particles which contain dihydroxy compounds and carbonic acid esters and to a process for the production thereof and to an apparatus for the production thereof and to the use thereof for the production of polycarbonate using the transesterification process and to a process for the production of polycarbonate using the transesterification process.
It is known to produce polycarbonate by transesterifying carbonic acid esters with dihydroxy compounds. The process is described, for example, in the monograph by H. Schnell,
Chemistry
&
Physics of Polycarbonate, Polymer Reviews
, volume 9, John Wiley & Sons, 1964, pp. 44-51. The process is also described in
Encyclopedia of Polymer Science
, volume 10, 1969.
The process for the production of polycarbonate by transesterification is in particular suitable for producing the bisphenol A homopolycarbonate. To this end, bisphenol A is transesterified with carbonic acid esters, preferably diphenyl carbonate. The process for the production of polycarbonate by transesterification is also suitable for producing copolycarbonates based on bisphenol A and further dihydroxy compounds as copolymerisation partners. To this end, bisphenol A and the further dihydroxy compounds are transesterified with carbonic acid esters, preferably diphenyl carbonate.
When producing polycarbonate by transesterification, the reactants (dihydroxy compounds and carbonic acid esters and optionally further auxiliary substances and additives, such as for example branching agents) are reacted in a multistage reaction, preferably as a melt, preferably with the addition of a transesterification catalyst or a combination of two or more transesterification catalysts with elimination of a hydroxy compound from the carbonic acid ester. If diphenyl carbonate is used as the carbonic acid ester, the hydroxy compound eliminated is phenol. The equilibrium of the reaction is steadily displaced by varying the temperature and pressure above the reaction mixture. In this manner, light-coloured, solvent-free polycarbonates may be obtained by continued condensation
Numerous catalysts, embodiments of the process and of the apparatus used have been described for the transesterification process for the production of polycarbonates.
The transesterification process for the production of polycarbonates has the advantage that neither solvents nor phosgene are required, as is the case with the “phase interface process” for the production of polycarbonates. The transesterification process for the production of polycarbonates thus allows polycarbonate to be produced in an economical and environmentally friendly manner, which polycarbonate additionally has the advantage that it contains no chlorine.
The process for the production of polycarbonate by transesterification generally places stringent requirements upon the purity of the starting materials and of the auxiliary substances used. Even the particular presentation of the starting materials and the auxiliary substances may have an influence upon the process and the quality of the polycarbonate produced.
The raw materials, dihydroxy compounds and carbonic acid esters used in the process for the production of polycarbonates by transesterification are, for example, introduced into the process as separate components and mixed, for example, during melting of the components. They may also both be introduced into the process as melts, such that the melts are mixed before the reaction. Such processes are described, for example, in EP-A 0 861 863.
A melt of a dihydroxy compound may be cooled to produce granules, flakes or prills in order to facilitate packaging, transport and storage, wherein prills exhibit advantages over granules or flakes due to their lower dust content and better flow characteristics.
It is known to produce solid particles, for example “prills”, which contain only one material for the production of polycarbonates by the transesterification process, for example bisphenol A.
Prills of dihydroxy compounds, in particular bisphenol A prills, may for example be produced by introducing molten dihydroxy compounds, in particular molten bisphenol A, into the top of a prilling tower via a spray head having a plurality of nozzles, into which prilling tower is introduced a countercurrently recirculated stream of cooling gas, wherein the prills which have cooled approximately to room temperature are collected at and discharged from the bottom of the prilling tower.
JP-6-107 581 discloses a process for the production of bisphenol A prills in which molten bisphenol A is introduced into the top zone of a prilling tower and cooling gas is introduced countercurrently at the bottom of the prilling tower, which gas draws the heat of fusion from the falling droplets of melt. The solidified prills are discharged from the bottom of the prilling tower.
Separate storage and separate transport of the two raw materials, dihydroxy compound and carbonic acid ester, for the process for the production of polycarbonate by transesterification entail significant logistical costs. Separate introduction of the two raw materials into the process for the production of polycarbonate by transesterification is likewise associated with elevated plant and equipment costs.
The object underlying the present invention was accordingly to provide a process for the production of polycarbonate by transesterification of dihydroxy compounds and carbonic acid esters, which process does not exhibit the disadvantages arising from the use of the two separate raw materials, dihydroxy compounds and carbonic acid esters, of the processes known from the prior art.
Said object of the invention is achieved by a process for the production of polycarbonate by transesterification of dihydroxy compounds and carbonic acid esters, wherein the dihydroxy compounds and the carbonic acid esters are introduced into the process in the form of solid particles which contain both dihydroxy compounds and carbonic acid esters.
The present invention accordingly provides a process for the production of polycarbonate by transesterifying carbonic acid esters with dihydroxy compounds, characterised in that the raw material used comprises solid particles which contain 10 to 90 parts by weight of a dihydroxy compound and 10 to 90 parts by weight of a carbonic acid ester.
It is possible in this process that further raw materials, other than the stated solid particles, are used for the process according to the invention. These may also comprise further dihydroxy compounds and/or carbonic acid esters. It is preferred to introduce the entire quantity of carbonic acid ester and dihydroxy compound required as starting material in the form of the solid particles according to the invention.
The present invention furthermore provides the use of solid particles which contain 10 to 90 parts by weight of a dihydroxy compound and 10 to 90 parts by weight of a carbonic acid ester for the production of polycarbonate by transesterification of carbonic acid esters with dihydroxy compounds.
The present invention furthermore provides solid particles, characterised in that they contain 10 to 90 parts by weight of a dihydroxy compound and 10 to 90 parts by weight of a carbonic acid ester.
The present invention furthermore provides a process for the production of solid particles, characterised in that a melt which contains 10 to 90 parts by weight of the dihydroxy compound and 10 to 90 parts by weight of the carbonic acid ester is cooled.
The present invention furthermore provides an apparatus for the production of solid particles which contain 10 to 90 parts by weight of a dihydroxy compound and 10 to 90 parts by weight of a carbonic acid ester, characterised in that the apparatus has two separate feed lines for the melt of the carbonic acid ester and for the melt of the dihydroxy compound and that these feed lines open into two separate heat exchangers and that the lines to convey the carbonic acid ester and the dihydroxy compound away from their particular heat exchangers are joined to combine the
Hucks Uwe
Lanze Rolf
Prein Michael
Bayer Aktiengesellschaft
Boykin Terressa
Gil Joseph C.
Preis Aron
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