Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Reexamination Certificate
2000-04-13
2001-07-17
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
Reexamination Certificate
active
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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Cummings Clark J.
Moore Eugene R.
Quarderer, Jr. George J.
Tirtowidjojo Danil
Boykin Terressa M.
The Dow Chemical Company
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