COMPOSITION BASED ON CC STATISTICAL COPOLYMER Russian patent published in 2021 - IPC C08L23/08 C08L23/14 C08J5/18 B32B27/32 

FIELD: material engineering.

SUBSTANCE: group of inventions includes a composition based on C₂C₃ statistical copolymer for use in the manufacture of a film, a method for obtaining this composition, the use of this composition, a sterilizable or sterilized film and a flexible packaging system. This composition includes: (A) from 70.0 to 99.9, wt. %, of C₂C₃ statistical copolymer, (B) from 0.0 to 30.0, wt. %, of ethylene-α-olefin plastomer with a density from 860 to 900 kg/m³ and melt flow index (MFI₂) at 190°C/2.16 kg, measured in accordance with ISO 1133, from 0.5 to 50.0 g/10 min and (C) one or more additives in a total amount from 0.1 to 5.0, wt. %, per composition. Static copolymer C₂C₃ (A) has (a) ethylene content from 2.0 to 4.8, wt. %; (b) MFI₂ at 230°C/2.16 kg, measured in accordance with ISO 1133, from 4.0 to 12.0 g/10 min; (c) the melting point determined by differential scanning calorimetry (DSC) in accordance with ISO 11357, from 120 to 135°C; (d) the content of the fraction soluble in cold xylene (XCS) is less than 10.0, wt. %. The additive (C) was selected from a group including antifriction agents, anti-adhesives, UV stabilizers, antistatic agents, alpha-nucleating agents and antioxidants. The method for obtaining this composition includes the steps: (i) obtaining a C₂C₃ statistical copolymer (A) by polymerization of propylene and ethylene through a sequential polymerization process involving at least two sequentially connected reactors in the presence of a metallocene catalyst; (ii) possibly mixing the specified C₂C₃ statistical copolymer (A) with an ethylene-α-olefin plastomer (B); (iii) addition of one or more additives (C) to obtain a mixture (A), possible (B) and (C) and (iv) extrusion of the specified mixture to obtain a composition based on the C₂C₃ statistical copolymer. Flexible packaging systems are selected from sacks or bags for packaging food and medicines.

EFFECT: development of a material having improved welding characteristics due to the low seal initiation temperature (SIT) and a high separation force in the hot state, as well as with excellent sterilization characteristics, that is maintaining a low level of turbidity after sterilization.

15 cl, 4 tbl, 4 ex