Process for polymerising olefins in the presence of an olefin polymerisation catalyst

1. A process for producing olefin polymers, said process comprising the steps of:

(i) forming in a catalyst feed vessel catalyst slurry comprising oil and a solid catalyst component;

(ii) maintaining the catalyst slurry in the catalyst feed vessel in a homogeneous state;

(iii) continuously withdrawing a portion of the catalyst slurry from the catalyst feed vessel and introducing the withdrawn portion of the catalyst slurry into a polymerization reactor;

(iv) continuously introducing at least one olefin monomer into the polymerization reactor;

(v) optionally, continuously introducing diluent and/or hydrogen into the polymerization reactor;

(vi) operating the polymerization reactor in such conditions that the at least one olefin monomer is polymerized by the polymerization catalyst to form a reaction mixture containing the catalyst, unreacted monomer(s), formed polymer and optionally diluent and/or hydrogen;

(vii) withdrawing a portion of the reaction mixture from the polymerization reactor, characterized in that the oil has a dynamic viscosity of from 30 to 990 mPa·s at the conditions within the catalyst feed vessel and the catalyst slurry is transferred by using a valveless piston pump from the catalyst feed vessel into the polymerization reactor.

2. The process according to claim 1 , wherein the polymerization is conducted in a loop reactor.

3. A process for producing olefin polymers, said process comprising the steps of:

(i) forming in a catalyst feed vessel catalyst slurry comprising oil, a solid catalyst component, and a drag reducing agent;

(ii) maintaining the catalyst slurry in the catalyst feed vessel in a homogeneous state;

(iii) continuously withdrawing a portion of the catalyst slurry from the catalyst feed vessel and introducing the withdrawn portion of the catalyst slurry into a polymerization reactor;

(iv) continuously introducing at least one olefin monomer into the polymerization reactor;

(v) optionally, continuously introducing diluent and/or hydrogen into the polymerization reactor;

(vi) operating the polymerization reactor in such conditions that the at least one olefin monomer is polymerized by the polymerization catalyst to form a reaction mixture containing the catalyst, unreacted monomer(s), formed polymer and optionally diluent and/or hydrogen; and

(vii) withdrawing a portion of the reaction mixture from the polymerization reactor, characterized in that the oil has a dynamic viscosity of from 20 to 1500 mPa·s at the conditions within the catalyst feed vessel and the catalyst slurry is transferred by using a valveless piston pump from the catalyst feed vessel into the polymerization reactor;

wherein the drag reducing agent is a polymer of one or more C 6 to C 15 alpha-olefins, and the drag reducing agent is present in an amount of 0.1 to 1000 parts per million by weight of the catalyst slurry.

4. The process according to claim 1 , wherein the reaction mixture is passed through a concentration device after it has been withdrawn from the reactor.

5. The process according to claim 1 , wherein the reaction mixture, is withdrawn continuously.

6. A process for producing olefin polymers, said process comprising the steps of:

(i) forming in a catalyst feed vessel catalyst slurry comprising oil and a solid catalyst component;

(ii) maintaining the catalyst slurry in the catalyst feed vessel in a homogeneous state;

(iii) continuously withdrawing a portion of the catalyst slurry from the catalyst feed vessel and introducing the withdrawn portion of the catalyst slurry into a polymerization reactor;

(iv) continuously introducing at least one olefin monomer into the polymerization reactor;

(v) optionally, continuously introducing diluent and/or hydrogen into the polymerization reactor;

(vi) operating the polymerization reactor in such conditions that the at least one olefin monomer is polymerized by the polymerization catalyst to form a reaction mixture containing the catalyst, unreacted monomer(s), formed polymer and optionally diluent and/or hydrogen;

(vii) withdrawing a portion of the reaction mixture from the polymerization reactor, characterized in that the oil has a dynamic viscosity of from 20 to 1500 mPa·s at the conditions within the catalyst feed vessel and the catalyst slurry is transferred by using a valveless piston pump from the catalyst feed vessel into the polymerization reactor and the catalyst slurry further comprises a drag reducing agent, which is a polymer of one or more C 6 to C 15 alpha-olefins.

7. A process for producing olefin polymers, said process comprising the steps of:

(i) forming in a catalyst feed vessel catalyst slurry comprising oil and a solid catalyst component;

(ii) maintaining the catalyst slurry in the catalyst feed vessel in a homogeneous state;

(iii) continuously withdrawing a portion of the catalyst slurry from the catalyst feed vessel and introducing the withdrawn portion of the catalyst slurry into a polymerization reactor;

(iv) continuously introducing at least one olefin monomer into the polymerization reactor;

(v) optionally, continuously introducing diluent and/or hydrogen into the polymerization reactor;

(vi) operating the polymerization reactor in such conditions that the at least one olefin monomer is polymerized by the polymerization catalyst to form a reaction mixture containing the catalyst, unreacted monomer(s), formed polymer and optionally diluent and/or hydrogen;

(vii) withdrawing a portion of the reaction mixture from the polymerization reactor, characterized in that the oil has a dynamic viscosity of from 30 to 990 mPa·s at the conditions within the catalyst feed vessel and the catalyst slurry is transferred by using a valveless piston pump from the catalyst feed vessel into the polymerization reactor and the catalyst slurry is contacted with one or more coactivator in a static mixer before introduction into the polymerization reactor.

8. The process according to claim 7 , wherein at least one coactivator is a trialkylaluminium.

9. The process according to claim 7 , wherein the catalyst system comprising the coactivator and the solid catalyst component has productivity of at least 3 kg polymer/g.

10. A composition comprising

(i) from 10 to 30% by weight of the total composition, a solid catalyst component;

(ii) from about 70 to about 90% by weight of the total composition, an oil having a viscosity of 20 to 1500 mPa·s; and

(iii) from 0.1 to 1000 part per million, based on the night of the total composition, a drag reducing agent, dissolved in said oil, which drag reducing agent is either a polymer comprising a majority of units derived from C 6 to C 15 alpha-olefins and/or an olefin polymer having an inherent viscosity of at least 10 dl/g.

11. The composition according to claim 10 , wherein the composition comprises from 0.5 to 100 parts per million by night of the drag reducing agent.

12. The composition according to claim 10 , wherein the drag reducing agent has a night average molecular night of at least 250000 g/mol.