METHOD OF PRODUCING POLYMERS Russian patent published in 2013 - IPC C08F6/00 C08F2/34 

FIELD: chemistry.

SUBSTANCE: apparatus includes a reaction vessel and a degassing vessel. In the method, each of the first and second processes includes the following steps: (a) bringing a main olefin and a comonomer into contact with a catalyst in gas-phase polymerisation conditions in a reaction vessel to obtain a first polymer or a second polymer, respectively, wherein said first and second methods employ the same main olefin, the difference between the two methods being at least one of the following factors: (1) the comonomer used and (2) the reaction temperature at which the polymer is obtained, and (b) subsequently bringing the first or second polymer, respectively, into contact with a blowout gas in a degassing vessel. The transition method involves changing the flow rate of the blowout gas in the degassing vessel from a first value X₁, which is used when degassing the first polymer, to a second value X₂, which is used when degassing the second polymer. The second value is determined relative the flow rate X_i and temperature T_i used at earlier steps of producing the polymer during transitional polymerisation using the same comonomer as in the second process, and reaction temperature T₂ in the second process. The method is characterised by that, (a) if T₂ increases relative T_i, X₂ is at least 1% lower than X_i when T₂ is raised every 1°C compared to T_i, (b) if T₂ drops relative T_i, X₂ is at least 1% higher than X_i when T₂ is decreased every 1°C compared to T_i, (c) if T₂ is equal to T_i, X₂ is equal to or greater than X_i, preferably equal to X_i.

EFFECT: if values X_i and T_i for earlier polymers are set for each comonomer to be used in successive polymerisation to obtain different polymers, the subsequent values of flow rate of the blowout gas X₂ for other polymers to be obtained can easily be determined based on said values and temperature T₂.

11 cl, 2 tbl, 1 ex