Process for producing a high molecular weight condensation...

Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...

Reexamination Certificate

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Reexamination Certificate

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06262226

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a process for producing a high molecular weight condensation polymer.
The weight average molecular weight (Mw) of a condensation polymer is frequently limited by the formation and presence of by-products during the polycondensation reaction. In these types of polycondensation equilibrium reactions, which are driven by the removal of a by-product, e.g. water, alcohol, phenol, etc., removal of the by-product enables the polymer chain end to react further, thus building the molecular weight of the polymer produced. However, methods of removing by-product(s) during the reaction process are difficult and costly due to the increased viscosity of the polymer produced. For example, DE-4,236,039 discloses a method for the production of condensation polymers by circulating the reaction mixture through tubular heat exchangers to remove a majority of the water by-product, further completing the reaction, and removing additional water by-product in a secondary similar stage. This process requires multiple reactors, and water removal stages. Other methods of solving the problem associated with removing unwanted by-products from polycondensation equilibrium reactions include diffusion and solid state polymerization processes. However, these methods incorporate long residence times, which can cause other additional by-products, such as color bodies or gels, to form.
Therefore, there remains a need for a more efficient and rapid process for removing by-product(s) from polycondensation equilibrium reaction mixtures and thus increasing the molecular weight of the condensation polymer produced.
SUMMARY OF THE INVENTION
The present invention is a process for producing a high molecular weight condensation polymer utilizing a centrifugal force device. The centrifugal force device causes the condensation polymer reaction mixture to flow such that thin films are formed and unwanted by-product(s) is rapidly diffused from the polymer reaction mixture to a vapor phase where it is removed via vacuum, allowing further reaction and molecular weight build-up of the polymer produced.
This process is an efficient and rapid method of removing unwanted by-product(s) from the polycondensation equilibrium reaction. This process further provides very short residence times and increased mass transfer.


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Melt Polycondensation of Poly(Ethylene Terephthalate) in a Rotatingdisk Reactor, S. I. Cheong et al, Journal of Applied Polymer Science, vol. 58, No. 9, pp. 1473-1483, 1995, John Wiley and Sons Inc., New York.
Chemical Abstract AN 110:24424,Analysis of the Rotating Drum Polycondensation Reactor for PET Synthesis, Kwan Han Yoon et al, Chemistry of Synthetic High Polymers.
Haw, Jimkuo; Mass Transfer of Centrifugally Enhanced Polymer Devolatilization by Using Foam Metal Packed Bed; Jan. 1995; Case Western Reserve University.

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