Modified polypropylenes of improved processability
AssigneeBorealis AG
InventorsManfred Raetzsch, Hartmut Bucka, Achim Hesse, Ulf Panzer, Norbert Reichelt
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Abstract
Modified polypropylenes of improved processability are produced by a continuous method by absorptively charging polypropylene particles at 20° to 120° C. with a gas mixture, which contains oxygen and bifunctional, unsaturated monomers, and melting the mixture. The modified polypropylenes of improved processability as well as mixtures with unmodified polypropylenes are suitable for the production of films, sheets, fibers, panels, coatings, pipes, hollow objects and foamed materials.
Claims14
A modified propylene homopolymer of improved processability produced by a continuous method from a propylene homopolymer having a melt index of 0.05 to 35 g/10 min at 230° C./2.16 kg and an ethylenically unsaturated, multifunctional monomer, in which the propylene homopolymer, in particulate form as powder, granulate or grit having particle sizes in the range of 0.001 to 7 mm, is treated with a gas mixture which consists of 5 to 65% by volume of ethylenically unsaturated, multifunctional monomer, which is readily volatile, and 95 to 35% by volume of inert gas or oxygen or an inert gas-oxygen mixture in any mixing ratio, wherein
- a) the treatment is conducted in a continuous mixer, with the gas mixture at a temperature of 20° C. to 120° C. and an average residence time of 10 seconds to 1,000 seconds and the particulate propylene homopolymer is in the solid phase, whereby the readily volatile, ethylenically unsaturated monomer is absorbed into the particulate propylene homopolymer without condensation of the readily volatile, ethylenically unsaturated monomer at the surfaces of the particulate propylene homopolymer in a proportion of 0.05 to 2% by weight, based on the weight of the particulate propylene homopolymer, without grafting thereonto,
- b) the particulate propylene homopolymer into which the readily volatile, multifunctional, ethylenically unsaturated monomer has been absorbed is melted under an atmosphere of said gas mixture at 110° C. to 210° C. during a residence time of 0.3 to 8.0 minutes whereby at least most of the multifunctional, ethylenically unsaturated monomer grafts onto the propylene homopolymer,
- c) the melt thereupon is heated to a temperature of 220° C. to 300° C. during a period of 0.3 to 7.0 minutes, unreacted, readily volatile, multifunctional, ethylenically unsaturated monomer and decomposition products being removed, and
- d) the melt is granulated.
A modified propylene copolymer of improved processability produced by a continuous method from a propylene copolymer of 85.0 to 99.9% by weight of propylene and 0.1 to 15.0% by weight of an α-olefin having 2 or 4 to 18 carbon atoms, the propylene copolymer having a melt index of 0.05 to 45 g/10 min at 230° C./2.16 kg, and an ethylenically unsaturated, multifunctional monomer in which the propylene copolymer, in particulate form as powder, granulate or grit having particle sizes in the range of 0.001 to 7 mm, is treated with a gas mixture which consists of 5 to 65% by volume of ethylenically unsaturated, multifunctional monomer, which is readily volatile, and 95 to 35% by volume of inert gas or oxygen or an inert gas-oxygen mixture in any mixing ratio, wherein
- a) the treatment is conducted in a continuous mixer, with the gas mixture at a temperature of 20° C. to 120° C. and an average residence time of 10 seconds to 1,000 seconds and the particulate propylene copolymer is in the solid phase, whereby the relatively volatile, ethylenically unsaturated monomer is absorbed into the particulate propylene copolymer without condensation of the readily volatile, ethylenically unsaturated monomer at the surfaces of the particular propylene homopolymer in a proportion of 0.05 to 2% by weight, based on the weight of the particulate propylene copolymer, without grafting thereonto,
- b) the particulate propylene copolymer into which the readily volatile, multifunctional, ethylenically unsaturated monomer has been absorbed is melted under an atmosphere of said gas mixture at 110° C. to 210° C. during a residence time of 0.3 to 8.0 minutes whereby at least most of the multifunctional, ethylenically unsaturated monomer grafts onto the propylene copolymer,
- c) the melt thereupon is heated to a temperature of 220° C. to 300° C. during a period of 0.3 to 7.0 minutes, unreacted, readily volatile, multifunctional, ethylenically unsaturated monomer and decomposition products being removed, and
- d) the melt is granulated.
Dependencies are inferred from the claim text.