METHOD OF PRODUCING LID OR CAP Russian patent published in 2024 - IPC C08J5/00 C08K5/00 C08L23/14 B65D41/00 C08F110/06 C08F210/06 C08F4/651 C08F4/646 C08F4/654 B29C45/00 

FIELD: packing and storage.

SUBSTANCE: invention relates to a method of producing a lid or cap. Method involves obtaining a polypropylene composition through sequential polymerisation, which involves the following steps: A) polymerisation in a first reactor, which is a loop reactor, in the presence of a Ziegler-Natta catalyst, propylene-containing monomers, and, optionally, one or more comonomers selected from ethylene and C₄-C₁₀ alpha-olefins, to obtain a first fraction of propylene polymer having a comonomer content of 0.0 to 1.8 wt.% and MFR 2 from 12.0 to 40.0 g/10 min, measured in accordance with ISO 1133 at 230 °C load 2.16 kg; B1) polymerisation in a second reactor, which is a first gas-phase reactor, of monomers containing propylene, and one or more comonomers selected from ethylene and C₄-C₁₀ alpha-olefins, in the presence of said first propylene polymer fraction, to obtain a second propylene polymer fraction, C) melting, extruding and moulding the polypropylene composition in the presence of at least one nucleating agent to form a lid or cap; and D) cooling the lid or cap obtained in step (C) at rate of 50 K/s or more. Polypropylene composition containing said first and second fractions of propylene polymer has MFR2 from 12.0 to 60.0 g/10 min, measured in accordance with ISO 1133 at 230 °C under load of 2.16 kg, has comonomer content from 2.2 to 5.0 wt.%, and ratio of comonomer content in component A) to comonomer content in said polypropylene composition is 0.35 or less.

EFFECT: providing a method of producing a lid or a cap with a shorter cycle for making the lid or cap due to faster crystallisation of the polypropylene composition in a wide range of cooling rates and especially at high cooling rates.

11 cl, 2 dwg, 4 tbl, 2 ex