Abstract:
A process for the preparation of random copolymer of propylene containing up to 6.0 % by weight of ethylene units, suitable for the manufacture of pipes, by copolymerizing propylene and ethylene in the presence of a catalyst system comprising the product obtained by contacting the following components: (a) a solid catalyst component comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least two electron donor compounds one of which being present in an amount from 40 to 90% by mol with respect to the total amount of donors and selected from succinates and the other being selected from 1,3 diethers, (b) n aluminum hydrocarbyl compound, and (c) optionally an external electron donor compound.
Abstract:
Fibers comprising a polypropylene obtainable by a process comprising the steps of: (i) polymerizing propylene in the presence of a catalyst system comprising the product obtained by contacting the following components: (a) a solid catalyst component comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least two electron donor compounds one of which being present in an amount from 40 to 90% by mol with respect to the total amount of donors and selected from succinates and the other being selected from 1,3 diethers, (b) an aluminum hydrocarbyl compound, and (c) optionally an external electron donor compound, to obtain a polypropylene precursor having a melt flow rate MFRl; (ii) subjecting the thus-obtained polypropylene precursor to visbreaking to obtain a visbroken polypropylene having a melt flow rate MFR2; (iii) spinning the visbroken polypropylene obtained in the previous step; wherein MFR2 is comprised between from 15 to 40 g/10min, the ratio MFR2/MFR1 is comprised between 8 and 18, both MFRl and MFR2 being measured according to ISO method 1133 (230° C, 2.16 kg).
Abstract:
There is described a method for monitoring and controlling the polymerization in a polymerization vessel by using a camera viewing unit to detect features of the polymer particles, or of their environment, compare them to pre-defined acceptable values of these features, or of their environment, and, if a variation from said pre-defined values is detected, acting on process parameters to reduce or eliminate said variation.
Abstract:
A propylene ethylene copolymer having: (i) an ethylene derived units content ranging from 2.0 wt% to 11.0 wt%; (ii) ) the fraction soluble in xylene at 25°C (Xs) ranging from 7.1 wt% to 28.5 wt%; (iii) the intrinsic viscosity of the fraction soluble in xylene at 25°C ranges from 3.2 dl/g to 5.6 dl/g; (iv) the melting point is higher than 140.0 °C and fulfils the following relation (I): Tm>155-1.4xC2 (I) (v) the flexural modulus is higher than 500MPa and fulfils the following relation (II) TM> 1900 - 285xC2+50xXs (II).
Abstract:
Process for the preparation of heterophasic propylene copolymer compositions (RAH ECO) comprising a random propylene copolymer (RACO) and an elastomeric propylene copolymer (BlPO), the process being carried out in a reactor having two interconnected polymerization zones, a riser and a down- comer, wherein the growing polymer particles: (a) flow through the first of said polymerization zones, the riser, under fast fluidization conditions in the presence of propylene and of ethylene and/or an alpha-olefin having from 4 to 10 carbon atoms, thus obtaining the random propylene copolymer (RACO); (b) leave the riser and enter the second of said polymerization zones, the downcomer, through which they flow downward in a densified form in the presence of propylene and of ethylene and/or an alpha-olefin having from 4 to 10 carbon atoms, wherein the concentration of ethylene and/or of the alpha-olefin in the downcomer is higher than in the riser, thus obtaining the elastomeric propylene copolymer (Bl PO); (c) leave the downcomer and are reintroduced into the riser, thus establishing a circulation of polymer between the riser and the downcomer.
Abstract:
A polyolefin composition, particularly fit for the production of extrusion blow molded articles, comprising (a) a propylene-ethylene copolymer having a content of units deriving from ethylene of 4.0 % by weight or higher, and (b) a nucleating agent and having a crystallization temperature (Tc) higher than 117°C can be obtained by copolymerizing propylene and ethylene in the presence of a catalyst system obtained by contacting a solid catalyst component comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least two electron donor compounds one of which being present in an amount from 40 to 90% by mol with respect to the total amount of donors and selected from succinates and the other selected from 1,3 diethers, an aluminum hydrocarbyl compound, and optionally an external electron donor compound.
Abstract:
A process and apparatus for producing olefin polymers are disclosed, comprising: a. polymerizing one or more olefins in the gas phase, in the presence of an olefin polymerization catalyst, whereby growing polymer particles flow along a cylindrically- shaped downward path in densified form under the action of gravity so as to form a densified bed of downward-flowing polymer particles b. allowing said polymer particles to flow through a restriction of the densified bed, such restriction being positioned in a restriction zone extending from the bed upward to a distance of 15% of the total height of the densified bed; and c. metering an antistatic agent through a feed line connected to the densified bed at a feed point being located in a feed zone extending from the top of the restriction upward, to a distance five times the diameter of the section of the densified bed above the restriction.
Abstract:
A processfor the preparation of propylene polymer compositions comprising from 50 to 90 % by weight of a propylene (co)polymer fraction insoluble in xylene at 25°C, and from 10 to 50% by weight of an ethylene copolymer fraction soluble in xylene at 25°C, said process comprising: (i)a first step of polymerizing propylene in the optional presence of ethylene and/or C 4 - C 10 alpha olefins, to produce a propylene (co)polymer being for at least 85% by weight insoluble in xylene at 25°C; and (ii)a successive step, carried out in gas-phase, in the presence of the product coming from step (i), of copolymerizing a mixture of ethylene with one or more α-olefins CH 2 =CHR in which R is a hydrocarbon radical having 1-10 carbon atoms, to produce an ethylene copolymer; the process being carried out in the presence of a catalyst system comprising: the product obtained by contacting: (a) a solid catalyst component comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least two internal electron donor compounds one of which being present in an amount from 35 to 90% by mol with respect to the total amount of donors and being selected from succinates and the other being selected from 1,3-diethers, the total amount of internal electron donor compounds being lower than 14.0% by weight with respect to the total weight of the solid catalyst component; with (b) an aluminum hydrocarbyl compound, and optionally with (c) an external electron donor compound.
Abstract:
A process for the gas-phase polymerization of α-olefms carried out in two interconnected polymerization zones, wherein the growing polymer particles flow through the first of said polymerization zones (riser) under fast fluidization conditions, leave said riser and enter the second of said polymerization zones (downcomer) through which they flow downward in a densified form, the process being characterized in that: (a) the gas mixture present in the riser is totally or partially prevented from entering the downcomer by introducing into the upper part of said downcomer a liquid stream LB having a composition different from the gaseous mixture present in the riser; (b) the ratio R between the flow rate F p of polymer circulated between said downcomer and said riser and the flow rate LB of said liquid being adjusted in a range from 10 to 50.
Abstract:
A process for the preparation of polyolefins carried out in the presence of an antistatic composition comprising: a) a compound of formula R-OH wherein R represents hydrogen or a linear or branched, saturated alkyl group having from 1 to 15 carbon atoms; and b) an oligomeric or polymeric organic compound having one or more terminal hydroxyl groups and a viscosity at 40 °C of at least 20 mm 2 /sec (DIN 51562).