POLYMERS OF ETHYLENE AND ESTERS THAT ARE NOT NECESSARILY ABLE TO COPOLYMERISE, FILMS PRODUCED WITH APPLICATION OF SUCH POLYMERS, AND METHODS OF STRETCHING PACKAGE IN FORM OF COVER WITH APPLICATION OF SUCH FILMS

摘要

FIELD: technological processes.;SUBSTANCE: present invention is related to polymers of ethylene and esters that are able to copolymerise, to films produced with application of such polymers. Polymer is described, which includes links derived from ethylene and possesses the following characteristics: a) flow-behavior index from 0.05 to 20 g/10 min, defined according to standard ASTM-1238, condition E; b) availability of at least 10 per 1000 C-atoms of short-chain branches that contain five or less carbon atoms, defined by ¹³C-NMR, and from 1 to 3 mole % of links derived from ester able to copolymerise and unsaturated with ethylene, c) density from 0.90 to 0.94 g/cm, defined according to standard ASTM D1505, and d) time of relaxation of at least 10 sec, calculated on the basis of shift speed and viscosity at the temperature of 230°C, with application of Cross model. Method is also described for free radical polymerisation for production of above mentioned polymer, and also multi-layer film is described, which includes the main layer with at least 50 wt % (per total mass of polymers in the main layer) of polymer by one of cl.1-8, at that specified film is characterised by elastic restoration after 100% stretching of at least 40% and provides for normalised retaining force for previous stretching at 100 mcm thickness at 85 % stretching after initial stretching for 100% of at least 20 N/50 mm, where above mentioned normalized retaining force is defined according to standard ASTM D5459, during a) stretching of film sample to 100% extension at the rate of slider motion of 1,000 mm/min, b) extension holding for 5 seconds, c) sample return to 85% extension, d) measurement of weight in N/50 mm after 60 second waiting time, e) calculation of normalised retaining force is done at measurement of retaining force provided that thickness of film makes 100 mcm.;EFFECT: improvement of operational properties of stretching packing films, improved balance between ability to stretch and retaining force.;26 cl, 9 dwg, 13 tbl, 1 ex