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EP-4737488-A1 - POLYETHYLENE-BASED MODIFIER, RECYCLED RESIN COMPOSITION, AND BLOWN CONTAINER

EP4737488A1EP 4737488 A1EP4737488 A1EP 4737488A1EP-4737488-A1

Abstract

In the molding of a polyethylene-based blow molded container, a recycled material is applied to the blow molded product, the usage of plastics is reduced, and the problem of plastic waste (waste plastics) is solved. In addition, by modifying the recycled material, a blow molded container with excellent durability is provided.

Inventors

  • TOMITA, Kota

Assignees

  • Japan Polyethylene Corporation

Dates

Publication Date
20260506
Application Date
20240628

Claims (7)

  1. A polyethylene-based modifier configured to modify a polyethylene-based recycled material satisfying the following properties (1-1) and (1-2): property (1-1): the polyethylene-based recycled material has a density of from 0.930 g/cm 3 to 0.980 g/cm 3 , and property (1-2): the polyethylene-based recycled material has a melt flow rate (MFR) of from 0.1 g/10 min to 10.0 g/10 min, which is measured at a temperature of 190°C under a load of 2.16 kg, and it has a high load melt flow rate (HLMFR) of from 1 g/10 min to 100 g/10 min, which is measured at a temperature of 190°C under a load of 21.6 kg, wherein the polyethylene-based modifier satisfies the following property (2-1): property (2-1): the polyethylene-based modifier has a b/a ratio of 0.90 or more where, a is the maximum of a component having 10 5 or less in a differential molecular weight distribution curve in a GPC measurement for polyethylene equivalent mass, and b is the maximum of a component having 10 5 or more.
  2. The polyethylene-based modifier according to claim 1, wherein the polyethylene-based modifier has a high load melt flow rate (HLMFR) of from 1 g/10 min to 20 g/10 min, which is measured at a temperature of 190°C under a load of 21.6 kg.
  3. The polyethylene-based modifier according to claim 1 or 2, wherein the polyethylene-based modifier has a melt flow rate (MFR) of 0.05 g/10 min or less, which is measured at a temperature of 190°C under a load of 2.16 kg.
  4. The polyethylene-based modifier according to any one of claims 1 to 3, wherein, when a total amount of the polyethylene contained in the polyethylene-based modifier is 100% by mass, an amount of a polyethylene component polymerized by a metallocene-based catalyst and contained in the polyethylene-based modifier is 40% by mass or more.
  5. A recycled resin composition comprising 1% by mass to 50% by mass of the polyethylene-based modifier according to any one of claims 1 to 4 and 99% by mass to 50% by mass of the polyethylene-based recycled material.
  6. The recycled resin composition according to claim 5, wherein the recycled resin composition satisfies the following properties (i) to (iii): property (i): a tensile impact strength is 120 kJ/m 2 or more, property (ii): a tensile strength by a full notch creep test (FNCT) is 16 hours or more, which is measured at 3.7 MPa according to ISO16770, and property (iii): a HLMFR is 10 g/10 min or more.
  7. A blow molded container comprising the recycled resin composition according to claim 5 or 6.

Description

Technical Field The present invention relates to a polyethylene-based modifier, a recycled resin composition and a blow molded container. Background Art In the field of blow molded containers, various kinds of thermoplastic resins are used. Of them, polyethylene has been subjected to various studies and widely used due to its excellent mechanical properties, thermal properties, chemical resistance and so on. In recent years, plastic waste (waste plastics) is a growing global problem, and a reduction in the usage of plastics and the introduction of new materials are under consideration. Some companies show attempts to review raw materials and build a new recycling system. Under such circumstances, the application of recycled materials to products has been studied in the field of blow molded containers made of synthetic resins. For example, Patent Document 1 discloses a polyolefin-based recycled resin composition comprising a polyolefin-based recycled resin and a copolymer of ethylene and an α-olefin containing 3 to 18 carbon atoms, the copolymer having specific properties and being produced in the presence of a metallocene-based catalyst. However, there is no suggestion of the amount of a high-molecular-weight component which is required from the viewpoint of modifying impact resistance and environmental stress cracking resistance, and the recycled polyolefin resin composition is not enough to be modified for blow molded containers. Also, Patent Document 2 discloses a resin composition for blow molding, comprising [A] a modifier for high-density polyethylenes and [B] a high-density polyethylene for blow molding which is other than [A]. The modifier for high-density polyethylenes comprises an ethylene polymer having the following properties: (1) a unit derived from a C3-C6 α-olefin may be contained in an amount of less than 10% by mole, (2) the density of the ethylene polymer is from 0.92 g/cm3 to 0.98 g/cm3, (3) the intrinsic viscosity [η] thereof is from 0.4 dl/g to 10 dl/g, and (4) the ethylene polymer is produced by use of a catalyst containing a metallocene compound represented by a specific structural formula. However, since the modifier has a wide range of properties, it cannot be said that the modifier is enough to provide, by modifying a recycled material, a blow molded container with excellent durability. As for polyethylene resins, for example, Patent Document 3 discloses a polyethylene resin composition which contains a specific polyethylene component (A) of from 10% by mass to 40% by mass, a specific polyethylene component (B) of from 5% by mass to 50% by mass, and a specific polyethylene component (C) of from 40% by mass to 85% by mass, and which satisfies the following properties (1) to (5). Property (1): the MFR is from 0.1 g/10 min to 1 g/10 min. Property (2): the HLMFR is from 10 g/10 min to 50 g/10 min. Property (3): the HLMFR/MFR ratio is from 50 to 140. Property (4): the density is from 0.940 g/cm to 0.965 g/cm. Property (5): an inflection point of elongation viscosity caused by strain hardening is observed in a double logarithmic plot of elongation viscosity η(t) (unit: Pa·sec) and elongation time t (unit: sec) measured at temperature of 170°C and an elongation strain rate of 0.1 (unit: 1/sec). Patent Document 3 also discloses that a molded body consisting of the polyethylene resin composition can be produced by various kinds of molding methods such as blow molding, injection molding, inflation molding and extrusion molding. However, there is no suggestion of the application of the polyethylene resin composition to the field of recycled materials. For example, Patent Document 4 discloses a polyethylene-based resin composition and a modifier, wherein the polyethylene-based resin composition is an ethylene-α-olefin copolymer obtained by multi-stage polymerization of specific components (A) and (B) in this order by use of a metallocene catalyst, and it satisfies specific characteristics including (i) density and (ii) HLMFR. However, there is no suggestion of their application to a specific recycled material and its field of use. For example, Patent Document 5 discloses a method for producing a recycled resin composition by mixing a recycled polyolefin resin with a resin composition containing a metallocene-based polyethylene. In particular, as the resin composition containing the metallocene-based polyethylene, a resin composition having the following properties is disclosed: a density of from 0.940 g/cm3 to 0.970 g/cm3, a MFR of from 0.1 g/10 min to 10 g/10 min, a HLMFR of from 10 g/10 min to 100 g/10 min, a HLMFR/MFR ratio of from 40 to 140, and a tensile impact strength of 300 kJ/m2 or more. However, since a resin composition (B) containing the metallocene-based polyethylene, which was used in "Examples", contained small amounts of high-molecular-weight components, it cannot be said that the recycled resin composition is enough to provide blow molded containers with excellent durability