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CN-115803391-B - Adhesive polyethylene composition

CN115803391BCN 115803391 BCN115803391 BCN 115803391BCN-115803391-B

Abstract

The present invention relates to an adhesive polyethylene composition comprising (A) 60 to 90% by weight of a non-elastomeric polyethylene, (B) 9.0 to 38% by weight of a vinyl elastomer being a copolymer of ethylene and an alpha-olefin comonomer unit having 4 to 12 carbon atoms, wherein an acidic grafting agent (C) has been grafted onto component (A) or components (A) and (B) in an amount of 0.01 to 3.0% by weight, all amounts being based on the total weight of the adhesive polyethylene composition, a multilayer structure comprising the adhesive polyethylene composition and the use of the adhesive polyethylene composition for producing a multilayer structure.

Inventors

  • Kajia Klimk
  • JOHN JAMISON
  • Jari Giuseppe rosskinimi
  • Flora Prade
  • Noureddine Agerald
  • TUA Sandholm
  • Juni pomonen
  • Angelica Legolas
  • ALBRECHT ANDREAS

Assignees

  • 博里利斯股份公司

Dates

Publication Date
20260508
Application Date
20210708
Priority Date
20200713

Claims (16)

  1. 1. An adhesive polyethylene composition comprising (A) 60 to 90 weight percent of a non-elastomeric polyethylene; (B) 9.0 to 38 weight percent of a vinyl elastomer which is a copolymer of ethylene and 1-octene; wherein the acidic grafting agent (C) has been grafted onto components (A) and (B) in an amount of from 0.01 to 3.0% by weight, all amounts being based on the total weight of the adhesive polyethylene composition.
  2. 2. The adhesive polyethylene composition of claim 1, wherein the non-elastomeric polyethylene is a copolymer of ethylene and one or more comonomer units selected from alpha-olefins having 4 to 12 carbon atoms.
  3. 3. The adhesive polyethylene composition according to claim 1 or 2, wherein the vinyl elastomer has a density of 840 to 900 kg/m 3 .
  4. 4. The adhesive polyethylene composition according to claim 1 or 2, wherein the acidic grafting agent (C) is selected from unsaturated carboxylic acids or derivatives thereof.
  5. 5. The adhesive polyethylene composition according to claim 1 or 2, having a polydispersity index PDI, i.e. the ratio of Mw/Mn, measured by GPC-VISC-LS analysis, of 1.5 to 4.5.
  6. 6. The adhesive polyethylene composition according to claim 1 or 2, having an elastic index EI at loss modulus g″=0.5 kPa of 75 to 320 Pa.
  7. 7. The adhesive polyethylene composition according to claim 1 or 2, having only one peak in a GPC curve, the GPC curve being defined as the concentration normalized LS 15 signal along the molecular weight of conventional GPC obtained from GPC-VISC-LS analysis.
  8. 8. The adhesive polyethylene composition according to claim 1 or 2, wherein the non-elastomeric polyethylene is a copolymer of ethylene and one comonomer selected from alpha-olefins having 4 to 12 carbon atoms.
  9. 9. The adhesive polyethylene composition according to claim 1 or 2, wherein the non-elastomeric polyethylene is a terpolymer of ethylene and two comonomers selected from alpha-olefins having 4 to 12 carbon atoms.
  10. 10. The adhesive polyethylene composition according to claim 1 or 2, obtainable by a process comprising the steps of -Feeding components (a), (B) and (C) into an extruder, into the feed section of the extruder comprising a feed section, a barrel section and a die plate, wherein the barrel section of the extruder downstream of the feed section and upstream of the die plate is divided into a plurality of control zones, a first control zone representing a first control zone within the barrel section downstream of the feed zone in which the components (a) and/or (B) fed start to melt; compounding the components (A) and (B) in the extruder to form the adhesive polyethylene composition, and -Grafting said components (a) and (B) with said component (C) during said compounding step.
  11. 11. The adhesive polyethylene composition according to claim 10, wherein the temperature of the second to last control zone in the barrel section is kept constant in all of these control zones, the total deviation not exceeding 20 ℃.
  12. 12. The adhesive polyethylene composition according to claim 10, wherein the method further comprises the steps of -Independently controlling the temperature of each of the plurality of control zones of the barrel section of the extruder such that A) The temperature of the first control zone of the barrel section downstream of the feed section is in the range of greater than 85 ℃ to 180 ℃, B) The temperature of the control zone of the barrel section from the first control zone of the barrel section downstream of the feed section to the control zone of the middle of the barrel section increases in two or more steps over the length of the barrel section such that the temperature of the control zone of the middle of the barrel section is 105% to 145% of the temperature of the first control zone of the barrel section downstream of the feed section, and C) The temperature of the control zone of the barrel section from the control zone in the middle of the barrel section to the control zone of the barrel section immediately upstream of the die plate is maintained at the same temperature or raised to a temperature of no more than 120% of the temperature of the control zone in the middle of the barrel section.
  13. 13. A multilayer structure comprising a layer comprising the adhesive polyethylene composition according to any one of claims 1 to 12.
  14. 14. The multilayer structure of claim 13, which is a three-layer coating of a metal tube.
  15. 15. The multilayer structure according to claim 13 or 14 having a peel strength at 23 ℃ of at least 350N/cm and/or a peel strength at 80 ℃ of at least 60N/cm.
  16. 16. Use of the adhesive polyethylene composition according to any one of claims 1 to 12 for producing a multilayer structure.

Description

Adhesive polyethylene composition Technical Field The present invention relates to an adhesive polyethylene composition, a multilayer coating comprising one layer comprising said adhesive polyethylene composition and the use of said adhesive polyethylene composition for producing an adhesive layer of a multilayer structure, such as a three-layer metal tube coating, having improved peel strength. Background Multilayer structures comprising two, three, four or more layers are known for a variety of applications. In these multilayer structures, the different layers are generally composed of different materials and thus have different physical and chemical properties. This causes problems in that adjacent layers do not adhere to each other or do not adhere to each other to an insufficient extent. It is therefore well known to construct a multilayer structure with an intermediate adhesive layer to improve the adhesion of adjacent layers composed of different materials to avoid delamination. A prominent example of a multilayer structure is a coating for metal tubes. Three layers of coating are typically provided on the outer surface of the metal pipe to protect the pipe from mechanical damage and corrosion. The three-layer coating is typically composed of an epoxy layer designed to adhere firmly to the outer surface of the pipe metal wall, an intermediate adhesive layer, and an outer polyolefin protective layer, typically high density polyethylene, crosslinked polyethylene or polypropylene. The three-layer structure shows improved properties compared to previously known single-layer coatings. On the one hand, the epoxy layer shows an improved bond with the metal wall, avoids cathodic disbonding and provides less oxygen permeation, while on the other hand, the outer polyolefin protective layer provides good mechanical protection and less water permeation. However, in order to avoid delamination of the polyolefin protective layer and the epoxy layer, which would lead to damage of the multilayer coating, an adhesive layer is required between the two layers. Adhesive compositions and methods for producing such adhesive compositions are known from EP 1,316,598 A1. Such adhesive compositions comprise a blend of a non-elastomeric polyethylene and an elastomer polymerized in the presence of a single site catalyst, wherein the non-elastomeric polyethylene or blend has been grafted with an acidic grafting agent. The coating layer comprising the adhesive composition shows good adhesion properties in the form of good peel strength. For three layer pipe coatings, ISO 21809-1:2011 specifies a minimum requirement for peel strength, wherein the peel strength of the class A coating is at least 100N/cm at 23 ℃, the peel strength of the class B coating is at least 150N/cm at 23 ℃, the peel strength of the class C coating is at least 250N/cm at 23 ℃, the peel strength of the class A coating is at least 20N/cm at 60 ℃, the peel strength of the class B coating is at least 30N/cm at 80 ℃, and the peel strength of the class C coating is at least 40N/cm at 90 ℃. Conversion technologies in the metal pipe coating market, and in particular in the steel pipe coating market, are moving towards faster line speeds and thicker steel pipes, which results in shorter water cooling times and often limits the available cooling capacity of the coating. Adhesive compositions currently used, such as for example the compositions disclosed in EP 1 316 598 A1, exhibit sensitivity to these conditions and often do not meet the peel strength requirements. Thus, there is a need for an adhesive composition suitable for use in multilayer structures such as three-layer metal pipe coatings that improves the peel strength of the coating over a shorter water cooling time. Surprisingly, it was found that adhesive compositions comprising a blend of non-elastomeric polyethylene and vinyl elastomer that have been grafted with an acidic grafting agent show improved adhesive properties, e.g. still show improved peel strength when used in coatings that have undergone a shorter water cooling time. Disclosure of Invention The present invention relates to an adhesive polyethylene composition comprising (A) 60 to 90 weight percent of a non-elastomeric polyethylene; (B) 9.0 to 38 weight percent of a vinyl elastomer which is a copolymer of ethylene and alpha-olefin comonomer units having 4 to 12 carbon atoms; Wherein the acidic grafting agent (C) has been grafted onto component (A) or components (A) and (B) in an amount of from 0.01 to 3.0% by weight, all amounts being based on the total weight of the adhesive polyethylene composition. Furthermore, the present invention relates to a multilayer structure comprising one layer comprising the adhesive polyethylene composition as described above or as described below. Furthermore, the present invention relates to the use of the adhesive polyethylene composition as described above or as described below for producing a multilayer struc