Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Patent
1992-01-22
1994-03-08
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
528486, 528488, C08F 626
Patent
active
052928624
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method for pyrolytically decomposing a polymer to continuously produce a low molecular weight polymer of quality in a simplified apparatus through simple steps, and more particularly, to a method for producing a pyrolytic wax by pyrolytically decomposing an olefin polymer and effectively removing volatile components resulting from the pyrolytic reaction from the reaction mixture using a simplified apparatus whereby a pyrolytic wax of quality having satisfactory hue and a minimal content of contaminants is continuously produced in a stable manner for a long period.
BACKGROUND OF THE INVENTION
Heretofore, low molecular weight polymers, for example, low molecular weight polyolefins such as polyethylene and polypropylene have been widely used as waxes in a variety of applications, for example, such as pigment dispersants, rubber processing aids, resin processing aids, additives to ink and coating compositions, fiber treating agents, and electrostatographic toners. In the recent years, the demand for such low molecular weight polymers in these applications is increasing and more strict requirements are imposed on their quality.
Known methods for producing low molecular weight polyolefins include telomerization of olefins, thermal degradation of high molecular weight polymers, and separation and purification of low molecular weight polymers by-produced during the preparation of high molecular weight polymers.
However, the previously proposed processes based on thermal degradation suffer from several problems in that the size of reactor is increased when a tank type reactor is used for batchwise mass production, and that control of reaction conditions such as temperature is difficult when a tubular reactor is used.
In the pyrolytic processes, volatile components including low molecular weight hydrocarbons are produced during pyrolysis of polyolefins, and if such volatile components, even in minor amounts, are left in the final product of pyrolytic wax, the pyrolytic wax becomes deteriorated in quality with respect to residual volatile content, smell, flash point, molecular weight distribution and the like. Further, the low molecular weight hydrocarbons can be oxidized with air entrained with the polyolefin feed and air incidentally admitted on the way of the process to thereby produce oxygenated hydrocarbons which will adversely affect the hue of the pyrolytic wax product, and the degree of separation of such hydrocarbons varies among separating techniques. It is thus necessary to effectively remove the volatile components in the production process.
Moreover, since the thermal degradation processes generally use severe reaction conditions, it is likely that low molecular weight fractions of the resulting polyolefin have poor hue due to thermal history and thermally deteriorated contaminants are formed in the reactor, and consequently, a continuous mode of production is difficult. To overcome this problem, a method of carrying out pyrolysis in the presence of steam-containing inert gas was proposed (Japanese Patent Publication No. 9368/1968). This method, however, imposes substantial limitations on the protection of apparatus against corrosion and the selection of apparatus material and adds complexity to reaction operation, leaving practical problems.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a method capable of pyrolytically decomposing a polymer to continuously produce low molecular weight polymers of quality in a simplified apparatus through simple steps.
A second object of the present invention is to provide a method capable of continuously producing a pyrolytic wax of quality having satisfactory hue and a minimal content of contaminants, due to controlled formation of thermally deteriorated contaminants in the reactor, in a stable manner for a long period.
A third object of the present invention is to provide a method capable of producing a pyrolytic wax of quality by pyrolytically decomposing a polymer, especially
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Inagaki Hajime
Itoh Yoshikuni
Miura Eigo
Morita Yoshinori
Nishiwaki Kenichi
Mitsui Petrochemical Industries Ltd.
Schofer Joseph L.
Weber Tom
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