Patent ID: 6593442
Filing Date: 2003-07-15
Classification: C08F,C08L,Y10S

Abstract:
A semicrystalline propylene polymer composition with good suitability for producing biaxially oriented films and prepared by polymerizing propylene, ethylene and/or C4-C18-1-alkenes, where at least 50 mol % of the monomer units present arise from the polymerization of propylene,and with a melting point TM of from 135 to 165Â° C., where the melting point TM is determined by Differential Scanning Calorimetry (DSC) to ISO 3146 by heating a previously melted specimen at a heating rate of 20Â° C./min, and is measured in Â° C., and is the maximum of the resultant curve, and where the semicrystalline propylene polymer composition can be broken down into from 40 to 85% by weight of a principal component A, from 0 to 55% by weight of an ancillary component B, and from 0 to 55% by weight of an ancillary component C, where the proportions of components A, B and C are determined by carrying out TREF (temperature rising elution fractionation) in which the polymers are firstly dissolved in boiling xylene and the solution is then cooled at a cooling rate of 10Â° C./h to 25Â° C., and then, as the temperature rises, that fraction of the propylene polymer composition which is soluble in xylene at (TM/2)+7.5Â° C. is then dissolved and separated off from the remaining solid, and then, as the temperature rises, at all of the higher temperatures 70Â° C., 75Â° C., 80Â° C., 85Â° C., 90Â° C., 94Â° C., 98Â° C., 102Â° C., 107Â° C., 112Â° C., 117Â° C., 122Â° C. and 125Â° C. the fractions soluble within the temperature range between this elution temperature and the preceding elution temperature are eluted, and the fractions taken into consideration during the evaluation which follows are those whose proportion by weight is at least 1% by weight of the initial weight of the propylene polymer composition specimen, and gel permeation chromatography (GPO) at 145Â° C. in 1,2,4-trichlorobenzene is used to measure the molar mass distribution of all of the fractions to be taken into consideration, and the principal component A is formed by all of the fractions which are eluted at above (TM/2)+7.5Â° C. and have an average molar mass Mn (number average)&gE;120,000 g/mol, the ancillary component B is formed by the fraction which is eluted at (TM/2)+7.5Â° C, and the ancillary component C is formed by all of the fractions to be taken into consideration which are eluted at above (TM/2)+7.5Â° C. and have an average molar mass Mn (number average)<120,000 g/mol, and where at least one of the fractions forming the principal component A has a ratio between weight-average (Mw) and number-average (Mn) molar masses of the polymers Mw/Mn>4.5.