Abstract:
The invention relates to a process for the preparation of porous ethylene polymers and to a specific group of ethylene polymers therefrom obtained. In particular, the present invention relates to a process for the preparation of ethylene (co)polymers characterized by: prepolymerizing propylene in the presence of a Mg, Ti, and halogen containing solid catalyst component having a porosity, higher than 0.25 cc/g up to producing from 0.1 to 15 g of propylene pre-polymer per g of catalyst component; and polymerizing ethylene in the presence of the propylene pre-polymer obtained in step (i) up to an amount of ethylene polymer ranging from 10 g to 2.5 kg per g of propylene pre-polymer.
Abstract:
A method of discharging polymer from a continuously operated polymerization reactor, wherein at least a monomer is polymerized to form polymer particles, the method comprising adjusting the discharge rate of the polymer particles by means of a piston valve having a piston element connected to an actuator, said actuator being able to modulate the piston stroke inside said piston valve.
Abstract:
The present invention relates to a solid catalyst component for the polymerization of olefins CH2=CHR in which R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms, comprising Mg, Ti, halogen and an electron donor selected from β-keto-ester derivatives of a particular formula. Said catalyst components when used in the polymerization of olefins, and in particular of propylene, are capable to give polymers in high yields and with high isotactic index expressed in terms of high xylene insolubility.
Abstract:
The present invention relates to propylene polymers made by using catalyst components for the polymerization of olefins comprising Mg, Ti, halogen and at least two electron donor compounds, said catalyst component being characterized by the fact that at least one of the electron donor compounds, present in an amount from 20 to 50% by mol with respect to the total amount of donors, is selected from esters of succinic acids which are not extractable, under the conditions described below, for more than 25% by mol and at least another electron donor compound which is extractable, under the same conditions, for more than 35%. The said catalyst component are capable to give polymers with high xylene insolubility, high stereoblock content and broad MWD suitable for making the polymers usable in the BOPP sector.
Abstract:
A process for preparing a catalyst component, comprising a Mg compound a Ti compound and an electron donor compound (ED) selected from alcohol, glycols, esters, ketones, amines, amides, nitrites, alkoxysilanes and aliphatic ethers as essential compounds, comprising two or more steps of reaction involving the use of at least one of said essential compounds as fresh reactant alone or in a mixture in which it constitutes the main component, said process being characterized by the fact that in the last of said one or more reaction steps the essential compound used as a fresh reactant is the ED compound.
Abstract:
A continuous process for minimizing the agglomeration of freshly manufactured polyolefin pellets comprising the steps of: feeding an aqueous stream containing polyolefin pellets to a tower, cooling said polyolefin pellets during their upward flow along said tower by means of a downward flow of a cooling agent having a density higher than said polyolefin, collecting the cooled pellets from the top of said tower after a residence time in the tower comprised between 2 and 20 minutes.
Abstract:
The present invention relates to MgCl2.(EtOH),m(ROH)n(H20)p adduct in which R is a C1-C15 hydrocarbon group different from ethyl, n and m are indexes, higher than 0, satisfying the equations (n+m)≧0.7 and 0.05≦n/(n+m)≦0.95 and p is a number ranging from 0 to 0.7 with the proviso that when R is methyl and (n+m) is in the range of 0.7 to 1, the value of n/(n+m) ranges from 0.05 to 0.45. The catalyst components obtained from the adducts of the present invention are capable to give catalysts for the polymerization of olefins characterized by enhanced activity with respect to the catalysts prepared from the adducts of the prior art.
Abstract:
Cyclopolyenic 1,3-diethers wherein the carbon atom in position 2 belongs to a particular cyclic or polycyclic structure containing two or three unsaturations, solid catalyst components and catalysts therefrom, the catalysts comprising the reaction product of: i. a solid catalyst component containing an internal donor; ii. an Al-alkyl compound, and optionally iii. an external donor; the internal donor and/or the external donor being cyclopolyenic 1,3-diethers. The catalysts are useful for the polymerization of alpha-olefins.
Abstract:
Biaxially oriented polypropylene films (BOPP) having at least one layer of a propylene polymer containing at least 0.8% by weight of ethylene and, optionally, one or more C4-C10 α-olefins, or a propylene polymer composition containing at least 0.8% by weight of one or more comonomers selected from the group consisting of ethylene and C4-C10 α-olefins, and having I) a melting temperature of 155° C. or higher; and II) a xylene soluble fraction at room temperature lower than 3% by weight, and a value of the ratio of the polymer fraction collected at the temperature range from 25° C. to 95° C. (by TREF) to the said xylene soluble fraction higher than 8.
Abstract:
A solid catalyst component for the polymerization of olefins made from or containing a magnesium halide, a titanium compound having at least a Ti-halogen bond, a first electron donor compound selected from 1,3 diethers (DE), and a second electron donor compound selected from dicarbamates (DC), wherein the first and second electron donor compounds are present in a molar ratio DE:DC ranging from 4.5:1 to 20:1.