A process for reducing the volatile organic compound content of granular plastomers having a density of equal to or lower than 883 kg/m.sup.3 and a MFR.sub.2 of 100.0 g/10 min or lower (ISO 1133 at 2.16 kg load and 190 C.), to below 65 ppm (VOC, VDA277), the process comprising the steps of providing a granular raw plastomer in a treatment vessel, the granular raw plastomer having a density of equal to or lower than 883 kg/m.sup.3, and a MFR.sub.2 of 100.0 g/10 min or lower (ISO 1133 at 2.16 kg load and 190 C.), and a volatile organic compound content (VOC, VDA277) of above 150 ppm, subjecting said granular raw plastomer to a gasflow within the range of 30 m.sup.3/(h t) to 150 m.sup.3/(h t) for an aeration time of less than 96 hours, whereby the gas has a minimum temperature of at least 26 C. measured at a gas inlet of the treatment vessel and a maximum temperature of 4 C. below the Vicat temperature (10 N, ISO 306) of the granular raw plastomer or 35 C. measured at the gas inlet of the treatment vessel, whatever value is lower; and recovering the granular plastomer.

The present application relates to a method for removing an unreacted vinyl chloride monomer (VCM) in polyvinyl chloride (PVC). According to an illustrative stripping apparatus and a stripping method using the stripping apparatus of the present application, in a stripping process using steam, a temperature difference between a raw material including a target substance to be removed and steam is minimized to suppress foam generation in the stripping process, thereby increasing efficiency of removing the target substance to be removed, particularly, an unreacted VCM in PVC. In addition, a cleansing cycle to remove foams generated in the stripping apparatus can be reduced, thereby not only securing economic feasibility of the process, but also preventing degradation in quality of a final product that may occur when an antifoamer to remove the foams is used.

The present application relates to a method for removing an unreacted vinyl chloride monomer (VCM) in polyvinyl chloride (PVC). According to an illustrative stripping apparatus and a stripping method using the stripping apparatus of the present application, in a stripping process using steam, a temperature difference between a raw material including a target substance to be removed and steam is minimized to suppress foam generation in the stripping process, thereby increasing efficiency of removing the target substance to be removed, particularly, an unreacted VCM in PVC. In addition, a cleansing cycle to remove foams generated in the stripping apparatus can be reduced, thereby not only securing economic feasibility of the process, but also preventing degradation in quality of a final product that may occur when an antifoamer to remove the foams is used.

A process for producing cycloalkenamer-containing compositions involves converting at least one cycloalkene by ring-opening metathetic polymerization to obtain a polyalkenamer-containing product mixture. The product mixture is worked up to remove monomers and oligomers of the cycloalkenes to obtain the polyalkenamer-containing composition by extraction with CO.sub.2. The extraction involves at least two stages: an extraction with liquid CO.sub.2 under the supercritical conditions, and then an extraction with supercritical CO.sub.2. Such cycloalkenamer-containing compositions can be used, for example, in the field of packaging materials, especially for food and drink.

This disclosure describes processes for producing polymer using non-polar and condensable stripping agents to remove volatile components, such as solvent and unreacted monomer, from the produced polymer. Systems for performing these processes are also disclosed.

Disclosed is a method for producing a polyolefin including: (1) a step (1) of polymerizing one or more olefins in solution polymerization or slurry polymerization in the presence of a polymerization catalyst to produce a polymer solution, (2) a step (2) of taking out the polymer solution obtained in the step (1), and adding a catalyst deactivator in the polymer solution to deactivate the polymerization catalyst, and (3) a step (3) of removing volatile components in vacuum from the polymer solution where the polymerization catalyst has been deactivated, and including, between the step (2) and the step (3), a step of adding an additive to the polymer solution when the water concentration in the polymer solution is 5 ppm by mass or less.

Methods according to the present invention decolorize a polymer by mixing a solution of the polymer with a photocatalyst and exposing the mixture to ultraviolet light; by way of non-limiting example, the polymer may be a star polymer and the photocatalyst may be titanium dioxide. Methods according to the present invention also utilize a metal scavenger, in some embodiments a solid-phase metal scavenger, to remove a metal catalyst from a polymer solution; by way of non-limiting example, the metal catalyst may be a tin catalyst. The decolorization methods and the catalyst removal methods of the present invention may be practiced separately, sequentially in any order, or simultaneously.

A method for controlling the temperature of the inner surface of a transfer line dryer, and thus controlling the temperature of a polymer product flowing through the transfer line dryer, is explained. Also provided is a transfer line dryer apparatus that is useful for implementing the disclosed method.

A method for controlling a residual monomer content of a polymer, wherein when a hot-air temperature and a hot-air velocity are maintained, the controlling method can predict the content of the residual monomer by controlling a hot-air mass ratio without influence of other external factors.

A method for controlling a residual monomer content of a polymer, wherein when a hot-air temperature and a hot-air velocity are maintained, the controlling method can predict the content of the residual monomer by controlling a hot-air mass ratio without influence of other external factors.