SOFT POLYOLEFIN COMPOSITIONS Russian patent published in 2007 - IPC C08L23/10 C08L23/16 C08F297/08 

FIELD: polymer materials.

SUBSTANCE: invention relates to polyolefin compositions for manufacturing elastic articles including following fractions: (A) 5 to 25% (everywhere by weight) crystalline polymer fraction selected from group consisting of propylene homopolymer having solubility in xylene below 10% at room temperature and copolymer of propylene and at least one α-olefin of general formula H₂C=CHR, wherein R represents H or linear or branched C₂-C₆-alkyl, comprising at least 80% propylene and having solubility in xylene below 15% at room temperature; (B) 75-92% elastomer fraction consisting of: (1) first elastomeric propylene copolymer with at least one α-olefin of general formula H₂C=CHR, wherein R represents H or linear or branched C₂-C₆-alkyl, optionally comprising 0.5 to 5% diene, said first elastomeric propylene copolymer containing 15 to 32% α-olefin, possessing solubility above 50% in xylene at room temperature and intrinsic viscosity of fraction dissolved in xylene from 3.0 to 5.0 dL/g; and (2) second elastomeric propylene copolymer with at least one α-olefin of general formula H₂C=CHR, wherein R is as above, optionally comprising 0.5 to 5% diene, said second elastomeric propylene copolymer containing 15 to 32% α-olefin, possessing solubility above 80% in xylene at room temperature and intrinsic viscosity of fraction dissolved in xylene from 4.0 to 6.5 dL/g. Weight ratio (1)/(2) lies within a range 1:5 to 5:1, bend elasticity module is below 60 MPa, Shore A hardness below 90, and residual 100% tensile deformation below 35%. A method for preparing such composition via consecutive polymerization conducted in presence of polymeric substance obtained in preceding step in presence of catalyst including trialkylaluminum compound, optionally electron donor, and solid catalytic component including titanium halide or halogen-alkoholate and electron donor compound deposited on anhydrous magnesium chloride. Described is also article, namely container for plasma or internal solutions, or instillation tube.

EFFECT: increased flexibility of polyolefin compositions and reduced modulus of elasticity at the same acceptable optical properties preserved.

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