RU2811037C1 - Adhesive polyethylene composition - Google Patents

Abstract

FIELD: polymers.

SUBSTANCE: polyethylene adhesive composition suitable for multi-layer structures. The specified composition contains (A) from 60 to 90 wt.% non-elastomeric polyethylene, which is a ternary copolymer of ethylene with two different alpha-olefin comonomer units having from 4 to 12 carbon atoms and (B) from 9.0 to 38 wt.% elastomer. Component (A) or components (A) and (B) are grafted with an acid grafting agent (C) in an amount of 0.01 to 3.0 wt.%, all based on the total weight of the adhesive polyethylene composition.

EFFECT: resulting adhesive compositions improve the peel strength of coatings subjected to reduced water cooling times.

15 cl, 2 dwg, 7 tbl, 2 ex

Description

The present invention relates to a polyethylene adhesive composition, a multilayer coating comprising one layer containing said polyethylene adhesive composition, and the use of said polyethylene adhesive composition to obtain a multilayer structure, such as an adhesive layer of a three-layer coating of metal pipes with increased peel strength.

State of the art

Multilayer structures comprising two, three, four or more layers are known for many applications. In these multilayer structures, the different layers are most often composed of different materials, which accordingly have different physical and chemical properties. This leads to the problem that adjacent layers do not adhere or only insufficiently adhere to each other. Therefore, it is common practice to create multilayer structures with intermediate adhesive layers to improve the adhesion of adjacent layers consisting of different materials and thus prevent delamination.

One well-known example of multilayer structures is coatings for metal pipes. Typically, a three-layer coating is applied to the outer surface of metal pipes to protect the pipe from mechanical damage and corrosion. The three-layer coating typically consists of an epoxy layer designed to firmly adhere to the outer surface of the metal pipe wall, an intermediate adhesive layer, and an outer polyolefin protective layer, which is usually high-density polyethylene, cross-linked polyethylene, or polypropylene. The three-layer structure shows improved properties compared to previously known single-layer coatings. On the one hand, the epoxy layer exhibits improved adhesion to the metal wall, prevents cathodic disbondment and provides less oxygen penetration, while on the other hand, the outer polyolefin protective layer provides good mechanical protection and less water penetration. However, to avoid delamination of the polyolefin protective layer and the epoxy layer, which could lead to damage to the multi-layer coating, an adhesive layer is required between both layers.

Adhesive compositions and methods for producing such adhesive compositions are known from EP 1316598 A1. This adhesive composition contains a mixture of non-elastomeric polyethylene polymerized in the presence of a single site catalyst and an elastomer where either the non-elastomeric polyethylene or the mixture is grafted with an acid grafting agent. The coating containing the adhesive layer containing the specified adhesive composition showed good adhesive properties in the form of good peel strength.

For three-layer pipe coatings, ISO 21809-1:2011 specifies minimum peel strength requirements of at least 100 Ncm at 23°C for class A coatings, at least 150 Ncm at 23°C for class B coatings and at least 250 N/cm at 23°C for class C coatings, and at least 20 N/cm at 60°C for class A coatings, at least 30 N/cm at 80°C for class B coatings and at least 40 N/cm at 90°C for class C coatings.

Technology transformation in the metal pipe coating market, especially in the steel pipe coating market, is changing towards higher line speeds and thicker steel pipes, resulting in shorter water cooling times and generally limiting the cooling capacity available to the coating. Currently used adhesive compositions, such as, for example, those disclosed in EP 1316598 A1, are sensitive to these conditions and often do not meet the requirements for peel strength.

Thus, there is a need for adhesive compositions suitable for multi-layer structures, such as three-layer coatings for metal pipes, that improve the peel strength of coatings subject to reduced water cooling times.

Surprisingly, it has been discovered that adhesive compositions comprising a mixture of a non-elastomeric polyethylene terpolymer, wherein the terpolymer is defined as a copolymer of ethylene with two different alpha-olefin comonomer units selected from alpha-olefins having from 4 to 12 carbon atoms, and an ethylene-based plastomer exhibit improved adhesive properties, such as increased peel strength, also when used in coatings that are subject to reduced water cooling times.

Brief description of the invention

The present invention relates to an adhesive polyethylene composition comprising

(A) from 60 to 90 wt. % non-elastomeric polyethylene, which is a ternary copolymer of ethylene with two different alpha-olefin comonomer units selected from alpha-olefins containing from 4 to 12 carbon atoms;

(B) from 9.0 to 38 wt. % elastomer;

wherein component (A) or components (A) and (B) are grafted with an acid grafting agent (C) in an amount from 0.01 to 3.0 wt. %, all based on the total weight of the adhesive polyethylene composition.

Moreover, the present invention relates to a multilayer structure including one layer containing an adhesive polyethylene composition as described above or below.

Moreover, the present invention relates to the use of a polyethylene adhesive composition, as described above or below, to obtain a multilayer structure.

Definitions

Polyethylene is a polymer in which molar amounts of monomer units are added to the total amount of at least 50 mol% ethylene monomer units.

"Ethylene homopolymer" means a polymer consisting primarily of ethylene monomer units. Due to the requirements of large scale polymerization, it may be possible that the ethylene homopolymer includes a minor amount of comonomer units, which is typically below 0.1 mol%, preferably below 0.05 mol%, most preferably below 0.01 mol% ethylene homopolymer .

A polymer is referred to as an "ethylene copolymer" if the polymer is derived from ethylene monomer units and at least one alpha-olefin comonomer.

A polymer is referred to as an "ethylene terpolymer" if the polymer is derived from ethylene monomer units and two different alpha-olefin comonomer units. An ethylene terpolymer with 1-butene comonomer units and 1-hexene comonomer units is a polymer containing, preferably consisting of, ethylene monomer units in a predominant molar amount, and 1-butene and 1-hexene comonomer units, each present in a lesser molar amount. quantity.

A polymer containing more than one fraction that differs from each other in at least one property, such as weight average molecular weight or comonomer content, is called "multimodal". If a multimodal polymer includes two different fractions, it is called "bimodal" and, accordingly, if it includes three different fractions, it is called "trimodal". The shape of the molecular weight distribution curve, i.e. the plot of the mass fraction of a polymer versus its molecular weight, such a multimodal polymer has two or more maxima depending on the modality or is at least clearly expanded compared to the curves of individual fractions.

Unlike a multimodal polymer, a unimodal polymer has only one maximum on the molecular weight distribution curve. A unimodal polymer includes only one polymer fraction, which cannot be distinguished by weight average molecular weight or comonomer content.

An elastomer is a polymer with viscoelasticity (i.e., both toughness and elasticity) and very weak intermolecular forces, and typically a low Young's modulus and high strain at failure compared to other materials. Elastomers are amorphous polymers maintained at temperatures above their glass transition temperature.

An acid grafting agent is a component containing an acid-based functional group that is grafted onto the polymer backbone. Suitable grafting methods include chemical treatment, photoirradiation or high-energy irradiation, whereby a radical is formed on the polymer backbone. The acid grafting agent then reacts with the radical and forms a bond with the polymer backbone. Most preferred is a chemical treatment initiated by an organic peroxide.

Extruders are conveyor devices that, using the principle of an Archimedean screw, uniformly extrude masses from solid to viscous from the molding hole under high pressure and high temperature. The extruder is mainly composed of a screw shaft, also called auger. It is located in the so-called cylinder. The nominal diameter of the cylinder bore is equal to the outer diameter of the screw. At the downstream end of the cylinder is a forming outlet, commonly called a die plate. At the downstream end of the cylinder there is a drive, in most cases an electric motor with a gearbox (extruder gearbox), which ensures rotation of the screw. The auger itself is usually divided into three sections that perform different tasks. In the part of the cylinder located downstream there is the so-called loading section. In the feed section, the material to be extruded is fed into the extruder through a hopper (“feed”). This is followed by a compression section in which the material is moved, melted and compacted. Further downstream in the compression section, the material is further compressed by the reduced thread depth of the screw, and thus the pressure necessary for unloading in the device is created. Finally, the discharge section ensures a uniform flow of material onto the spun plate. In the present invention, the term "cylindrical section" covers the portions of the cylinder that surround the compression section and the discharge section of the screw upstream of the feed section and downstream of the spinneret plate. The cylindrical section is heated. The heating of the cylindrical section can be independently controlled in so-called “control zones”. In the present invention, the so-called “first control zone” is a first control zone in the cylindrical section downstream of the feed zone in which the material, typically components (A) and/or (B) and possibly component (C), begins to melt. Therefore, the temperature of the first control zone is set at a level from above 85°C to 180°C.

The amounts below are given in % by weight (wt%) unless otherwise noted.

Brief Description of the Drawings Figure 1 shows a comparison of the GPC curve on a graph of normalized CP 15 concentration versus log M of examples CE1, IE1 and IE2.

Figure 2 shows the GPC curve for determining molecular weights plotting dW/dlog M versus log M (CP) of examples CE1, IE1 and IE2.

DETAILED DESCRIPTION OF THE INVENTION In one aspect, the present invention relates to a polyethylene adhesive composition comprising

(A) from 60 to 90 wt. % non-elastomeric polyethylene, which is a ternary copolymer of ethylene with two different alpha-olefin comonomer units selected from alpha-olefins containing from 4 to 12 carbon atoms;

(B) from 9.0 to 38 wt. % elastomer;

wherein component (A) or components (A) and (B) are grafted with an acid grafting agent (C) in an amount from 0.01 to 3.0 wt. %, all based on the total weight of the adhesive polyethylene composition.

Non-elastomeric polyethylene (A)

Non-elastomeric polyethylene (A) is a ternary copolymer of ethylene with two different alpha-olefin comonomer units selected from alpha-olefins containing from 4 to 12 carbon atoms.

"Different" in this context means that the alpha-olefin comonomer units differ in the number of carbon atoms and therefore in the length of the short-chain branches in the polymer chain of the terpolymer.

The two different alpha-olefin comonomer units are preferably selected from 1-butene, 1-hexene, 1-octene, 1-decene, most preferably 1-butene and 1-hexene. It is therefore particularly preferred that the non-elastomeric polyethylene is a terpolymer of ethylene with 1-butene comonomer units and 1-hexene comonomer units.

A terpolymer of ethylene with two different alpha-olefin comonomer units selected from alpha-olefins containing from 4 to 12 carbon atoms, preferably 1-butene and 1-hexene, may contain additional comonomer units selected from alpha-olefins other than said two different alpha-olefin comonomer units, such as propylene, 1-pentene, 4-methyl-1-pentene, 1-octene, 1-decene, styrene and mixtures thereof.

However, preferably the ternary copolymer of ethylene with two different alpha-olefin comonomer units selected from alpha-olefins containing from 4 to 12 carbon atoms, consists of ethylene and said two different alpha-olefin comonomer units, preferably consists of ethylene, 1-butene and 1-hexene.

Typically, the total number of comonomer units in a ternary copolymer is up to 30.0 wt. % of the total weight of the copolymer, more preferably up to 10.0 wt. % of the total weight of the ternary copolymer and most preferably up to 6.0 wt. % of the total mass of the ternary copolymer.

The lower limit of the total number of comonomer units in a copolymer is usually 0.5 wt. % of the total weight of the terpolymer, more preferably 1.0 wt. % of the total mass of the ternary copolymer.

The number of first alpha-olefin comonomer units, preferably 1-butene comonomer units, is preferably up to 10.0 wt. in the terpolymer. % of the total weight of the ternary copolymer, more preferably up to 4.0 wt. % of the total weight of the ternary copolymer and most preferably is up to 1.5 wt. % of the total mass of the ternary copolymer.

The lower limit of the total number of first alpha-olefin comonomer units, preferably 1-butene comonomer units, is typically 0.1 wt. % of the total weight of the terpolymer, more preferably 0.3 wt. % of the total mass of the ternary copolymer.

The number of second alpha-olefin comonomer units, preferably 1-hexene comonomer units, is preferably up to 20.0 wt. in the terpolymer. % of the total weight of the terpolymer, more preferably up to 6.0 wt. % of the total weight of the ternary copolymer and most preferably is up to 4.5 wt. % of the total mass of the ternary copolymer.

The lower limit of the total number of second alpha-olefin comonomer units, preferably 1-hexene comonomer units, is typically 0.4 wt. % of the total weight of the terpolymer, more preferably 0.7 wt. % of the total mass of the ternary copolymer.

Non-elastomeric polyethylene (A) is preferably present in the adhesive polyethylene composition in an amount of from 60 to 90 wt. %, preferably from 65 to 85 wt. % and, in particular, from 70 to 80 wt. % of the total amount of adhesive polyethylene composition.

Moreover, preferably, the non-elastomeric polyethylene (A) has a melt flow index MFR ₂ of 1.0 to 10.0 g/10 min, more preferably 3.0 to 8.0 g/10 min, before grafting. MFR ₂ is measured in accordance with ISO 1133 at a temperature of 190°C under a load of 2.16 kg.

The density of the non-elastomeric polyethylene (A) is preferably 900 to 960 kg/m ³ , more preferably 920 to 950 kg/m ³ and most preferably 925 to 945 kg/m ³ .

In addition, the non-elastomeric polyethylene (A) preferably has a polydispersity (PD), defined as the ratio of weight average molecular weight to number average molecular weight, Mw/Mn, from 1.5 to 5.0, more preferably from 1.7 to 4.0 and most preferably 1.9 to 3.0 as determined by GPC-VIASC-CP analysis.

The weight average molecular weight Mw (CP) of the non-elastomeric polyethylene (A) is preferably 30,000 g/mol to 75,000 g/mol, more preferably 40,000 g/mol to 65,000 g/mol, and most preferably 45,000 g/mol to 60,000 g/mol when determined using GPC-VIAZK-SR analysis.

The Z average molecular weight Mz (CP) of the non-elastomer polyethylene (A) is preferably 75,000 g/mol to 200,000 g/mol, more preferably 80,000 g/mol to 175,000 g/mol, and most preferably 85,000 g/mol to 150,000 g/ mole as determined by GPC-VIASK-CP analysis.

Non-elastomeric polyethylene (A) preferably has a single peak in a GPC measurement, where the GPC curve is defined as the concentration-normalized CP 15 signal to the molecular weight of conventional GPC obtained from the GPC-VIASK-CP analysis.

Moreover, the non-elastomeric polyethylene (A) preferably has a vinyl group content per 100,000 carbon atoms of greater than 0.6, such as 1.0 to 15.0, more preferably 2.5 to 10.0, most preferably 4.0 to 7.5.

When polymerized in the presence of a Ziegler-Natta catalyst, the non-elastomeric polyethylene (A) preferably has a higher vinyl group content per 100,000 carbon atoms of 17.5 to 50.0, more preferably 20.0 to 45.0, most preferably 25.0 up to 40.0.

In addition, the non-elastomeric polyethylene (A) preferably has a total number of unsaturated bonds per 100,000 carbon atoms from 7.5 to 30.0, for example from 10.0 to 27.5, more preferably from 15.0 to 22.5, most preferably 15.0 to 22.5, determined by quantitative nuclear magnetic resonance (NMR) spectroscopy in solution.

The non-elastomeric polyethylene (A) adhesive resin composition is preferably produced in a process including a metal single site catalyst.

In this case, non-elastomeric polyethylene (A) can be produced in a multiphase polymerization method using, for example, suspension and/or gas-phase reactors or in a single-phase method, such as a solution polymerization method.

In one embodiment, non-elastomeric polyethylene (A) is polymerized in a multiphase polymerization process using a single site metal polymerization catalyst.

Preferably, in said embodiment, the non-elastomeric polyethylene (A) is produced in a process containing a metallocene catalyst. In addition, preferably the catalyst includes a metallocene component on a porous support and an aluminoxane component.

Preferred catalysts are those described in EP 0678103, WO 97/28170, WO 98/56831 and/or WO 00/34341.

Preferably, non-elastomeric polyethylene (A) is produced by the process described in EP 0678103, which is characterized in that ethylene is polymerized in suspension using a supported olefin polymerization catalyst obtained by

(1) providing a porous support that is an inorganic oxide of an element selected from groups 2 to 4 and 13 to 14 of the Periodic Table of the Elements, preferably alumina or silicon dioxide,

(2) obtaining a solution containing (2.1) the reaction product (2.1.1) of the metallocene of formula (1)

where Cp is an unsubstituted or substituted and/or fused homo- or heterocyclopentadienyl, R is a group of 1-4 atoms connecting two rings of Cp, M is a transition metal of group 4, 5 or 6 of the Periodic Table of the Elements, preferably zirconium or hafnium , R' represents a hydrocarbyl or hydrocarboxyl group having 1-20 carbon atoms, and X represents a halogen atom, wherein m=1-3, n=0 or 1, o=0-3, p=0-3 and sum m+n+p=oxidation state M, and

(2.1.2) alumoxane of formula (2)

where formula (II) describes a linear connection, and/or formula (3)

where formula (III) describes a cyclic compound, and in formulas (2) and (3) x is 1-40, preferably 10-20, y is 3-40, preferably 3-20, and R'' represents an alkyl group, having 1-20 carbon atoms and

(2.2) a solvent capable of dissolving the specified reaction product,

(3) impregnating the porous support with a volume of solution not exceeding the total pore volume of the porous support, and

(4) removing the impregnated porous carrier, the pores of which are filled with the specified solution.

The preferred embodiments of the catalyst given in EP 0678103 are also preferred for the production of non-elastomeric polyethylene (A).

Other preferred metal single site catalysts are described in EP 688794, EP 949274, WO 95/12622, WO 00/34341 and WO 00/40620. Most preferred is the catalyst described in WO 95/12622, and its preferred embodiments described therein.

In another embodiment, non-elastomeric polyethylene (A) is polymerized in a single-phase polymerization process using a single site metal polymerization catalyst.

Preferably, in said embodiment, the non-elastomeric polyethylene (A) is produced in a process including a metallocene catalyst.

Thus, the polymerization catalyst system may be a metallocene catalyst as described in WO-A-1993025590, US-A-5001205, WO-A1987003604 and US-A-5001244, or it may be combinations thereof.

Other suitable catalysts, such as late transition metal catalysts, can also be used.

Preferably, the polymerization catalyst system includes a metallocene catalyst.

According to one embodiment, the catalyst system for polymerization comprises

(i) at least one metallocene complex of formula (I)

Where

Mt1 represents Hf,

X represents a sigma donor ligand,

R1, R2, R3 are the same or different and may be hydrogen or saturated linear or branched C1-C10 alkyl, wherein the alkyl group may optionally contain up to 2 heteroatoms belonging to groups 14-16 of the Periodic Table, or R1 and R2 or R2 and R3 can form a ring containing from 4 to 6 carbon atoms and from 1 to 3 double bonds,

R4 and R5 are the same or different and may be saturated linear or branched C1-C10 alkyl, C5-C10 aryl, C6-C20 alkylaryl or C6-C20 arylalkyl groups, which may optionally contain up to 2 heteroatoms belonging to groups 14-16 of the Periodic Table elements,

n can be from 1 to 5,

Ar represents a C6-C20 aryl or -heteroaryl group, which may be unsubstituted or substituted with 1 to 5 linear or branched C1-C10 alkyl groups,

And

(ii) an alumoxane cocatalyst and

(iii) optionally an aluminum alkyl compound A1(R7)3, where R7 represents a linear or branched C2-C8 alkyl group.

This type of catalyst is described in more detail in WO 2018/178151 A1, the contents of which are incorporated herein by reference.

According to one embodiment, the catalyst system for polymerization comprises

(i) at least one metallocene complex of formula (II)

Where

Mt1 represents Hf,

X is a sigma donor ligand,

R1, R2, R3 are the same or different and may be hydrogen or saturated linear or branched C1-C10 alkyl, wherein the alkyl group may optionally contain up to 2 heteroatoms belonging to groups 14-16 of the Periodic Table of the Elements, or R1 and R2 or R2 and R3 can form a ring containing 4 to 6 carbon atoms and 1 to 3 double bonds,

R4 and R5 are the same or different and may be saturated linear or branched C1-C10 alkyl, C5-C10 aryl, C6-C20 alkylaryl or C6-C20 arylalkyl groups, which may optionally contain up to 2 heteroatoms belonging to groups 14-16 of the Periodic Table elements,

n can be from 1 to 5,

Ar represents a C6-C20 aryl or heteroaryl group, which may be unsubstituted or substituted with 1 to 5 linear or branched C1-C10 alkyl groups,

And

(ii) boron-containing cocatalyst.

This type of catalyst is described in more detail in WO 2018/178152 A1, the contents of which are incorporated herein by reference.

According to one embodiment, the catalyst system for polymerization comprises

(i) metallocene complex of formula (III)

Where

M represents Hf or a mixture with Zr, provided that more than 50 mol. % of the complex of formula I has M=Hf,

X represents a sigma ligand,

R are the same or different and may be saturated linear or branched C1-C10 alkyl, C5-C10 aryl, C6-C20 alkylaryl or C6-C20 arylalkyl groups, which may optionally contain up to 2 heteroatoms or silicon atoms,

R1 is C6-C20 aryl, which may be unsubstituted or substituted with one or up to 5 linear or branched C1-C10 alkyl groups,

R2 is a saturated linear or cyclic C3-C20 alkyl group or a branched CR3R4R5 group, where R3 is hydrogen or a C1-C20 alkyl group, and R4 and R5 are the same or different and may represent a C1-C20 alkyl group.

And

(ii) boron-containing cocatalyst.

This type of catalyst is described in more detail in WO 2018/108917 A1, the contents of which are incorporated herein by reference.

According to one embodiment, the polymerization catalyst system comprises

(i) metallocene complex of formula (IV)

Where

M represents Hf or a mixture with Zr, provided that more than 50 mol. % of the complex of formula I has M=Hf;

X represents a sigma ligand;

R are the same or different and may be saturated linear or branched C1-C10 alkyl, C6-C10 aryl, C4-C10 heteroaryl, C6-C20 alkylaryl or C6-C20 arylalkyl groups, which may optionally contain up to 2 heteroatoms or silicon atoms;

R1 represents a C6-C10 aryl or C6-C20 alkylaryl group, optionally containing up to 2 heteroatoms or silicon atoms, or a C4-C10 heteroaryl group;

R2 represents a C4-C20 cycloalkyl group, optionally containing alkyl substituents at the beta positions, formula (V)

where R' may be the same or different and may be hydrogen, or is defined as R, and n is from 1 to 17; And

(ii) boron-containing cocatalyst.

A catalyst of this type is described in more detail in WO 2018/108918 A1, the contents of which are incorporated herein by reference.

Other suitable metallocene catalysts are described in WO 2015/158790 A1 and WO 2015/158791 A1.

When producing non-elastomeric polyethylene (A) in a multi-phase process, non-elastomeric polyethylene (A) is preferably produced in a multi-stage process in a multi-stage reaction sequence such as described in WO 92/12182. In this process, in the first stage, ethylene and one of two comonomer units, preferably 1-butene, are polymerized in a loop reactor in the liquid phase of an inert low-boiling hydrocarbon medium, preferably to produce an ethylene-alpha-olefin copolymer fraction, preferably an ethylene-1-butene copolymer fraction . The reaction mixture after polymerization is then discharged from the loop reactor and at least a substantial portion of the inert hydrocarbon is separated from the polymer fraction. The polymer fraction is then transferred to a second or subsequent stage in one or more gas phase reactors where polymerization continues in the presence of ethylene gas and the second of the two comonomer units, preferably 1-hexene, to produce an ethylene-alpha-olefin copolymer fraction, preferably the ethylene-1 fraction -hexene copolymer. The polymer obtained in accordance with this process has excellent homogeneity with respect to the distribution of the various polymer fractions, which cannot be achieved, for example, with a polymer mixture. In another embodiment of this multiphase process, in both stages polymer fractions are polymerized from ethylene and both alpha-olefin comonomer units, preferably 1-butene and 1-hexene, resulting in two terpolymer fractions.

In yet another embodiment of this multiphase process, in one step, preferably the first step, the ethylene homopolymer fraction is polymerized, while in another step, preferably the second step, the terpolymer fraction of ethylene and both alpha-olefin comonomer units, preferably 1-butene, is polymerized and 1-hexene.

In this case, the first embodiment of the polymerization of two fractions of ethylene comonomer with different alpha-olefin comonomer units in two stages is preferred.

When producing non-elastomeric polyethylene (A) in a single-phase process, non-elastomeric polyethylene (A) is preferably produced by a solution method, for example as described in WO 2017/108951 A1 or WO 2017/108969 A1. Here, a solution containing the catalyst components, ethylene monomer, two different alpha-olefin comonomers, preferably 1-butene and 1-hexene, and hydrogen, is usually introduced into a polymerization reactor operating at a temperature of from 120°C to 250°C, for example , from 140°C to 220°C, most preferably from 150°C to 200°C, depending on the content of comonomer units in the polymer, and pressure from 5 to 30 MPa (50 to 300 bar), preferably from 6 to 25 MPa (60 to 250 bar) and more preferably 7 to 20 MPa (70 to 200 bar).

The non-elastomeric polyethylene (A) may be a unimodal polyethylene or a multimodal polyethylene.

In one embodiment, the non-elastomeric polyethylene (A) may be a multimodal polyethylene. Moreover, a preferred multimodal polyethylene is bimodal polyethylene.

The expression “polymer modality” in this regard preferably does not refer to the shape of its molecular weight distribution (MWD) curve, i.e. the appearance of a graph of the dependence of the mass fraction of a polymer on its molecular weight, but to the comonomer units in the polymer chain. Preferably, the terpolymer of ethylene and 1-butene comonomer units and 1-hexene comonomer units as described above is composed of two kinds of polymer chains, one kind is a polymer chain of ethylene monomer units and 1-butene comonomer units, and the other kind is is a polymer chain of ethylene monomer units and 1-hexene comonomer units.

It is preferable that the polymerization conditions in different polymerization reactors do not differ too much, so that the molecular weights of the various polymer fractions are in a comparable range.

In another embodiment, the non-elastomeric polyethylene (A) is a unimodal polyethylene.

In this embodiment, a unimodal polyethylene, such as a terpolymer of ethylene and 1-butene comonomers and 1-hexene comonomers as described above, is typically polymerized in a single polymerization reactor.

Unimodal polyethylene can also be polymerized in two or more polymerization reactors using polymerization conditions that allow the polymerization of polyethylene fractions having substantially the same properties.

Elastomer (B)

The elastomer (B) is preferably selected from copolymers of ethylene with polar comonomer units, olefin block copolymers or mixtures thereof, more preferably from copolymers of ethylene with polar comonomer units.

The elastomer (B) may be olefin block copolymers such as a propylene block copolymer or an ethylene block copolymer. Examples of such elastomers include ethylene propylene rubber, ethylene propylene diene rubber (EPDM) and ethylene propylene norbornadiene rubber.

More preferably, the elastomer (B) is an elastomeric copolymer of ethylene with one or more polar comonomer units. The polar comonomer units are preferably selected from alkyl acrylates, alkyl methacrylates and alkyl acetates. Preferred examples of such elastomers are ethylene alkyl acrylates, ethylene alkyl methacrylates and ethylene alkyl acetates. In addition, preferably the comonomer has a polar moiety of the formula

-O(CO)C1-C6-alkyl or -C(O)-OC1-C6-alkyl.

Particularly preferred elastomers are ethylene vinyl acetate (EVA), ethylene methyl acrylate (EMA), ethylene methyl methacrylate (EMMA), ethylene propyl acrylate and ethylene butyl acrylate (EBA), in particular EBA.

The number of polar comonomer units in the elastomer (B) is preferably from 15 to 40 mass. %, more preferably from 17 to 35 wt. %, most preferably from 20 to 30 wt. %.

The elastomer (B) may further contain at least one alpha-olefin comonomer selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene , 1,4-butadiene and 1,4-hexadiene.

The elastomer (B) typically has a density of from 900 to 960 kg/m ³ , preferably from 910 to 945 kg/m ³ , more preferably from 915 to 935 kg/m ³ , most preferably in the range from 920 to 930 kg/m ³ .

MFR ₂ (ISO 1133; 190°C; 2.16 kg) of elastomer (B) before grafting is from 0.5 to 10.0 g/10 min, preferably from 0.7 to 9.0 g/10 min, more preferably from 0.9 to 8.0 g/10 min and even more preferably from 1.0 to 7.5 g/10 min.

Polydispersity (PD), Mw/Mn of the elastomer (B) is most often from 7.5 to 17.5, more preferably from 9.0 to 15.0 and most preferably from 10.0 to 13.0, when determined using GPC-VIAZK-SR analysis.

The weight average molecular weight Mw (CP) of the elastomer (B) is preferably 100,000 g/mol to 300,000 g/mol, more preferably 125,000 g/mol to 275,000 g/mol, and most preferably 150,000 g/mol to 250,000 g/mol at determination using GPC-VIAZK-SR analysis.

The Z average molecular weight Mz (CP) of the elastomer (B) is preferably 500,000 g/mol to 1,500,000 g/mol, more preferably 750,000 g/mol to 1,300,000 g/mol, and most preferably 1,000,000 g/mol to 1,250,000 g/mol , when determined using GPC-VIAZK-SR analysis.

The elastomer (B) preferably has a Z-score of 2.5 to 20, more preferably 3.5 to 17.5, and most preferably 5.0 to 15.0 when measured by GPC, where the GPC curve is defined as concentration normalized CP signal 15 by traditional GPC molecular weight obtained from GPC-VIASK-SR analysis.

The elastomer (B) preferably has a slope of 0.1 to 5.0, more preferably 0.5 to 4.0, and most preferably 1.0 to 3.0 when measured by GPC, where the GPC curve is defined as concentration normalized CP 15 molecular weight signal of traditional GPC obtained from GPC-VIASK-SR analysis.

In addition, the elastomer (B) preferably has a vinyl group content per 1000 carbon atoms of 2.0 to 25.0, more preferably 3.5 to 20.0, most preferably 5.0 to 15.0, as determined by quantitative spectroscopy nuclear magnetic resonance (NMR) in solution.

In addition, the elastomer (B) preferably has a total number of unsaturated bonds per 100,000 carbon atoms from 10.0 to 75.0, for example from 15.0 to 60.0, most preferably from 20.0 to 50.0, determined by quantitative nuclear magnetic resonance (NMR) spectroscopy in solution.

The elastomer elastomer (B) can be produced by any suitable method known in the art.

Preferably, the elastomer (B) is present in the adhesive polyethylene composition in an amount of from 9.0 to 38 wt. %, more preferably from 15 to 35 wt. % and most preferably from 20 to 30 wt. % based on the total amount of adhesive polyethylene composition.

Acid Grafting Agent (C) The acid grafting agent can be any such agent known to one skilled in the art to be suitable for this purpose.

Preferably, the acid grafting agent is an unsaturated carboxylic acid or a derivative thereof, such as anhydrides, esters and salts (both metallic and non-metallic). Preferably, the unsaturated group is conjugated with a carboxyl group.

Examples of such grafting agents include acrylic acid, methacrylic acid, fumaric acid, maleic acid, nadic acid, citraconic acid, itaconic acid, crotonic acid and their anhydrides, metal salts, esters, amides or imides.

Preferred grafting agents are maleic acid and its derivatives such as maleic anhydride and in particular maleic anhydride.

Preferably, the acid grafting agent (C) is present in the adhesive polyethylene composition in an amount of from 0.01 to 3.0 wt. %, more preferably from 0.03 to 1.5 wt. % and most preferably from 0.05 to 1.0 wt. % based on the total amount of adhesive polyethylene composition.

Component (D)

Grafting can be carried out in the presence or absence of a radical initiator (D), but is preferably carried out in the presence of a radical initiator (D), such as an organic peroxide, an organic perester or an organic hydroperoxide.

The most preferred radical initiator (D) is selected from organic peroxides.

Preferably, the radical initiator (D), more preferably an organic peroxide, is dissolved in a solvent before being introduced into the extruder feed zone.

A suitable organic peroxide may be selected from dialkyl peroxides such as, for example, lauroyl peroxide, didecanoyl peroxide, tert-butyl cumyl peroxide, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane, 2,5-bis(tert-butylperoxy)-2 ,5-dimethylhexane, tert-butylcumyl peroxide, tert-butylperoxypivalate, di(tert-butylperoxyisopropyl)benzene and mixtures thereof, preferably 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane, 2,5-bis(tert- butylperoxy)-2,5-dimethylhexane, di(tert-butylperoxyisopropyl)benzene and mixtures thereof. Solid radical initiators (D) can be dissolved in a solvent such as isododecane.

The amount of radical initiator is preferably from 0 wt. % up to 0.50 wt. %), more preferably from 0.001 wt. % up to 0.40 wt. % and most preferably from 0.01 wt. % up to 0.25 wt. %, based on the total amount of adhesive polyethylene composition.

Supplements

The adhesive polyethylene composition may contain additional additives.

Suitable additives are those customary for use with polyolefins, such as stabilizers (eg antioxidants), metal scavengers and/or UV stabilizers, antistatic agents and auxiliary agents (such as processing aids). The additives are preferably selected so that they cannot react with the radical initiator (D) under the conditions of the process for producing the polyethylene adhesive composition according to the invention, as described above or below.

The amount of additives is preferably from 0 wt. % up to 1 wt. %, more preferably from 0.001 wt. % up to 0.8 wt. %, based on the total amount of adhesive polyethylene composition.

Vaccination method

An adhesive polyethylene composition as described above or below is prepared by grafting an acid grafting agent (C) onto component (A) or both components (A) and (B).

The grafting can be carried out by any method known in the art, such as melt grafting without a solvent, or in a solution, or in a dispersion, or in a fluidized bed. Typically, grafting is carried out in a heated extruder or mixer, such as described in US 3236917 A, US 4639495 A, US 4950541 A or US 5194509 A. The contents of these documents are incorporated herein by reference. Typically grafting is carried out in a twin-screw extruder such as that described in US 4,950,541 A.

Preferably, the polyethylene adhesive composition as defined above or below can be produced by a method for producing a polyethylene adhesive composition as described above or below, comprising the steps

- feeding components (A), (B) and (C) into the extruder;

- compounding components (A) and (B) in an extruder to obtain an adhesive polyethylene composition and

- grafting component (A) or components (A) and (B) with component (C) during the compounding step.

The extruder preferably includes a feed section, a cylindrical section and a spun plate, wherein the cylindrical section of the extruder downstream of the feed section and upstream of the spun plate is divided into a plurality of control zones, and the first control zone is a first control zone in the downstream cylindrical section. flow from the loading zone in which the feed component(s) (A) and/or (B) begin to melt.

Components (A), (B) and (C) are preferably fed together into the feed section of the extruder.

Components (A), (B) and (C) are preferably mixed to form a mixture of components (A), (B) and (C). The specified mixture is the material supplied to the loading section of the extruder.

Preferably, components (A), (B) and (C), preferably a mixture of components (A), (B) and (C), are supplied to the extruder feed section through a hopper.

Alternatively, components (A) and (B) are preferably supplied to the loading section. Then component (C) can also be supplied to the loading section as well as to the cylindrical section, preferably to the control zone of the cylindrical section set to a temperature of 180°C or lower.

Preferably, components (A) and (B) are supplied to the feed section of the extruder, and component (C) is supplied to the barrel section, preferably to a control zone of the barrel section set to a temperature of 180° C. or lower.

If necessary, additional additives can be supplied to the extruder as described above or below. Preferably, additional additives are supplied to the cylindrical section of the extruder. These additional additives or other polymer components can also be supplied along with component (C) to the control zone of the cylindrical section set at a temperature of 180°C or lower. However, preferably these additional additives or other polymer components are supplied to one of the downstream control zones of the extruder barrel, preferably a barrel control zone set at a temperature greater than 180°C.

The temperature in the loading section is preferably below 100°C, for example from 20°C to 70°C, more preferably from 20°C to 60°C, even more preferably from 25°C to 60°C, even more preferably from 30°C C to 60°C and most preferably from 35°C to 50°C.

Preferably, the grafting reaction is initiated by feeding a radical initiator (D) into the extruder. The radical initiator (D) can be supplied to the extruder feed section separately from components (A), (B) and (C), for example, through a side feeder. The radical initiator (D) can also be supplied to the extruder barrel, for example, together with component (C), for example, in a control zone set at a temperature of 180°C or lower.

The extruder is preferably a twin screw extruder, more preferably a co-rotating twin screw extruder.

The extruder may be, for example, any commonly used extruder. As an example of an extruder for the present compounding step, extruders supplied by Japan Steel Works or Coperion, such as ZSK co-rotating twin screw extruders with different screw diameters, can be used.

An extruder suitable for the method of the present invention may be a laboratory scale extruder or an industrial scale extruder.

In a laboratory scale extruder, the extrusion step is usually carried out at a feed rate of 1 kg/h to 100 kg/h, more preferably 5 kg/h to 50 kg/h. In an industrial scale extruder, the throughput is typically from 1 to 50 t/h, more preferably from 1.5 to 10 t/h.

The extruder screw speed is preferably 170 to 550 rpm, more preferably 200 to 500 rpm.

Preferably, at said extrusion stage, the SPI (Specific Power Input) of the extruder may be from 150 kWh/t to 350 kWh/t, more preferably from 170 kWh/t to 300 kWh/t, wherein the SPI is calculated directly from the power consumption of the extruder without taking given its inherent limited effectiveness.

The extruder temperature at the die plate is preferably 180°C to 250°C, more preferably 185°C to 230°C, most preferably 195°C to 230°C.

The cylindrical section of the extruder preferably includes at least 5 control zones, in each of which the temperature is controlled independently. Suitably the cylindrical section contains from 5 to 15 control zones, preferably from 6 to 12 control zones.

The temperature profile in the cylindrical section can be adjusted in two different embodiments, which typically results in different grafting patterns of the adhesive polyethylene composition depending on needs.

In the first embodiment, the temperature from the second to the last control zone in the cylindrical section is maintained constant in all these control zones with a total deviation of no more than 20°C, preferably no more than 15°C, most preferably no more than 10°C (constant temperature profile).

The temperature of the first control zone of the cylindrical section downstream of the loading zone may be lower or in the same range as the temperature of the second to last control zone in the cylindrical section.

The temperature of the first control zone is preferably from 165°C to 210°C, preferably from 170°C to 200°C, and most preferably from 175°C to 190°C.

The temperature from the second to last control zone in the cylindrical section is preferably 180°C to 250°C, more preferably 185°C to 230°C, most preferably 195°C to 230°C.

In a second embodiment, the temperature of the control zones in the cylindrical section from the first control zone in the cylindrical section downstream of the loading section to the control zone in the middle of the cylindrical section increases along the length of the cylindrical section in 2 or more stages (temperature rise profile).

This means that for a cylindrical section consisting of 5 or 6 control zones, the temperature of control zones 1-3 increases.

For a cylindrical section consisting of 7 or 8 control zones, the temperature of control zones 1-4 increases.

For a cylindrical section consisting of 9 or 10 control zones, the temperature of control zones 1-5 increases.

For a cylindrical section consisting of 11 or 12 control zones, the temperature of control zones 1-6 increases.

For a cylindrical section consisting of 13 or 14 control zones, the temperature of control zones 1-7 increases.

For a cylindrical section consisting of 15 control zones, the temperature of control zones 1-8 increases.

A temperature increase in two or more stages means that along the length of the cylindrical section from the first control zone of the cylindrical section downstream of the loading section to the control zone in the middle of the cylindrical section, the temperature of two or more cylinders, for example, from two to five cylinders, preferably two or three cylinders, most preferably two cylinders, are set higher than the cylinder temperature upstream of said two or more cylinders.

The temperature of the control zones of the cylindrical section from the first control zone of the cylindrical section downstream of the loading section to the control zone in the middle of the cylindrical section is usually increased in two to five stages, for example, in two stages, three stages, four stages or five stages, preferably in two stages - four stages and more preferably two or three stages. In most extruders, two temperature steps are sufficient for the process described above or below.

The temperature increase in the two or more temperature raising steps is preferably 5°C to 30°C, more preferably 7.5°C to 25°C, most preferably 10°C to 20°C independently for each step.

The temperature of the control zones of the cylindrical section from the first control zone of the cylindrical section downstream of the loading section to the control zone in the middle of the cylindrical section is increased in two or more stages so that the temperature of the control zone in the middle of the cylindrical section is from 105% to 145%, more preferably from 110% to 140% and most preferably from 110% to 135% of the temperature in the first control zone of the cylindrical section downstream of the loading section.

The temperature of the first control zone of the cylindrical section downstream of the loading section is from greater than 85°C to 180°C, preferably from 120°C to 180°C, more preferably from 130°C to 175°C, and most preferably from 140°C up to 170°C.

The temperature of the control zone in the middle of the cylindrical section is preferably 15-60°C higher, more preferably 20-40°C higher, than the temperature in the first control zone of the cylindrical section.

Preferably, the temperature of the control zones increases from the first control zone of the cylindrical section to the control zone in the middle of the cylindrical section in increments of 5 to 20°C from the control zone to the adjacent control zone.

The temperature of the control zones of the cylindrical section from the control zone in the middle of the cylindrical section to the control zone of the cylindrical section immediately in front of the spun plate is maintained at the same level or increased to a temperature of no more than 120%, more preferably no more than 115%, even more preferably no more than 110% of the zone temperature regulation in the middle of the cylindrical section.

This means that for a cylindrical section including 5 or 6 control zones, the temperature of control zones 3-5 or 6 is maintained the same or increased to a temperature of no more than 120% of the temperature of control zone 3.

For a cylindrical section including 7 or 8 control zones, the temperature of control zones 4-7 or 8 is maintained the same or increased to a temperature of no more than 120% of the temperature of control zone 4.

For a cylindrical section including 9 or 10 control zones, the temperature of control zones 5-9 or 10 is maintained the same or increased to a temperature of no more than 120% of the temperature of control zone 5.

For a cylindrical section including 11 or 12 control zones, the temperature of control zones 6-11 or 12 is maintained the same or increased to a temperature of no more than 120% of the temperature of control zone 5.

For a cylindrical section including 13 or 14 control zones, the temperature of control zones 7-13 or 14 is maintained the same or increased to a temperature of no more than 120% of the temperature of control zone 5.

For a cylindrical section including 15 control zones, the temperature of control zones 8-15 is maintained the same or increased to a temperature of no more than 120% of the temperature of control zone 5.

When increasing, the temperature of the last control zone of the cylindrical section is preferably 5°C - 30°C higher, more preferably 10°C - 20°C, than the temperature in the control zone in the middle of the cylindrical section.

When maintained, the temperature in the last control zone of the cylindrical section is the same as the temperature in the control zone in the middle of the cylindrical section.

From the first to the last control zone of the cylindrical section, the temperature is preferably increased by 115-150%, more preferably from 120% to 145%, and most preferably from 125% to 135% of the temperature of the first control zone of the cylindrical section.

The temperature of the last control zone of the cylindrical section is preferably 30°C to 75°C higher, more preferably 35°C to 70°C, and most preferably 40°C to 60°C higher than the temperature of the first control zone of the cylindrical section.

The temperature of the last control zone of the cylindrical section may be the same as the temperature of the die plate.

In one particularly preferred embodiment, the cylindrical section has 6 control zones in which the temperature is independently controlled.

The loading zone is preferably set at 35°C - 50°C.

The control zone 1 is preferably set to 140°C - 170°C.

The control zone 2 is preferably set to 170°C - 180°C.

The control zone 3 is preferably set to 180°C - 190°C.

The control zone 4 is preferably set to 190°C - 200°C.

The control zone 5 is preferably set to 190°C - 210°C.

The control zone 6 is preferably set to 190°C - 210°C.

The spin plate is preferably set at 190°C - 210°C.

The measured temperature in the control zones of all embodiments, as discussed above, may differ from the set temperatures by ±5°C, preferably ±4°C.

Adhesive polyethylene composition

The adhesive polyethylene composition contains a non-elastomeric polyethylene (A) and an ethylene-based elastomer (B) that is grafted with an acid grafting agent (C) as described above or below. Components (A), (B) and (C) of the polyethylene adhesive composition are preferably as defined above or below.

The adhesive polyethylene composition may further contain the additives specified above or below.

The adhesive polyethylene composition preferably has a MFI ₂ value of the final composition (after grafting) from 0.1 to 10.0 g/10 min, more preferably from 0.8 to 6.0 g/10 min, and most preferably from 1.0 to 5 .0 g/10 min.

The adhesive polyethylene composition preferably has a density of from 900 to 960 kg/m ³ , more preferably from 920 to 950 kg/m ³ and most preferably from 925 to 945 kg/m ³ .

In addition, the adhesive polyethylene composition preferably has a rheological polydispersity index 1111 of less than 1.50, such as 0.50 to 1.40, more preferably 0.65 to 1.25, most preferably 0.75 to 1.00.

The adhesive polyethylene composition preferably has a shear thinning index ORS _(1/100) of not more than 20.0, for example from 5.0 to 17.5, more preferably from 7.5 to 16.5, and most preferably from 10.0 up to 15.0.

The adhesive polyethylene composition preferably has a shear thinning index ORS _(2.7/210) of not more than 25.0, for example from 7.5 to 22.5, more preferably from 10.0 to 20.0, and most preferably from 12 .5 to 17.5.

In addition, the adhesive polyethylene composition preferably has an elasticity index with a loss modulus G''=0.5 kPa PE(0.5 kPa) from 250 to 500 Pa, more preferably from 275 to 450 Pa, most preferably from 300 to 400 Pa.

In addition, the adhesive polyethylene composition preferably has an elasticity index with a loss modulus G''=2 kPa PE (2 kPa) from 750 to 1500 Pa, more preferably from 850 to 1350 Pa, most preferably from 950 to 1200 Pa.

In addition, the adhesive polyethylene composition preferably has an elasticity index with a loss modulus G''=5 kPa PE (5 kPa) from 1750 to 4000 Pa, more preferably from 2000 to 3500 Pa, most preferably from 2200 to 3250 Pa.

In addition, the adhesive polyethylene composition preferably has a melting point Tm from 110 to 150°C, more preferably from 115 to 135°C, most preferably from 120 to 130°C. The heat of fusion of Npl is preferably 90 to 125 J/g, more preferably 95 to 115 J/g, most preferably 100 to 110 J/g.

In addition, the adhesive polyethylene composition preferably has a crystallization temperature Tcr of 90 to 130°C, more preferably 95 to 120°C, most preferably 100 to 115°C. The heat of crystallization Hcr is preferably 95 to 130 J/g, more preferably 100 to 125 J/g, most preferably 105 to 120 J/g.

Moreover, the adhesive polyethylene composition preferably has a glass transition temperature of -30.0°C to -60.0°C, more preferably -40.0°C to -55.0°C, and most preferably -42.5°C C to -50.0°C, when measured using dynamic mechanical thermal analysis (DMTA).

In addition, the adhesive polyethylene composition preferably has a dynamic modulus of elasticity at 23°C of 150 to 300 MPa, more preferably 165 to 250 MPa, most preferably 180 to 225 MPa, as measured by dynamic mechanical thermal analysis (DMTA).

Preferably, the adhesive polyethylene composition has a vinyl group content per 100,000 carbon atoms of 1.0 to 15.0, more preferably 2.0 to 12.5, even more preferably 3.0 to 10.0, most preferably 4.0 up to 7.5, determined by quantitative nuclear magnetic resonance (NMR) spectroscopy in solution.

In addition, the adhesive polyethylene composition preferably has a total number of unsaturated bonds per 100,000 carbon atoms from 10.0 to 30.0, more preferably from 12.5 to 27.5, most preferably from 15.0 to 25.0, as determined by quantitative spectroscopy nuclear magnetic resonance (NMR) in solution.

As discussed above, two different embodiments of the temperature profile in the extruder barrel during the grafting process, a constant temperature profile and a ramped temperature profile, typically result in different grafting patterns. This different nature of grafting affects the GPC data, especially when it is obtained from the GPC-VIASK-SR analysis, as described below in the section related to measurement methods.

In general, regardless of the temperature profile in the cylindrical section, the adhesive polyethylene composition has the following GPC properties.

The adhesive polyethylene composition preferably has a mean molecular weight Mz (CP) of 300,000 g/mol to 1,250,000 g/mol, more preferably 350,000 g/mol to 1,100,000 g/mol, even more preferably 375,000 g/mol to 1,000,000 g/mol and most preferably from 400,000 to 900,000 g/mol as determined by GPC-VIASC-CP analysis.

In addition, the adhesive polyethylene composition preferably has a weight average molecular weight Mw (CP) of 90,000 to 175,000 g/mol, more preferably 100,000 to 150,000 g/mol, and most preferably 117,000 to 135,000 g/mol as determined by GPC-YNAD analysis -SR.

The polydispersity index (PDI), which is the Mw/Mn ratio, of the polyethylene adhesive composition is preferably 2.5 to 8.5, more preferably 3.5 to 7.5, and most preferably 4.0 to 6.5 , when determined using GPC-VIAZK-SR analysis.

The adhesive polyethylene composition preferably has two distinct peaks and a valley between said peaks in the GPC curve. The GPC curve is defined below in the section on measurement methods as the concentration-normalized CP 15 signal to the molecular weight of conventional GPC, obtained from the GPC-VIAZK-SR analysis.

The adhesive polyethylene composition preferably has a Z value of -5.0 or higher, more preferably at least -4.0, even more preferably at least -3.5, most preferably at least -3.0. The Z value can be as high as 5.0, preferably 2.5, more preferably 1.5.

The slope s between the two peaks of the GPC curve of the polyethylene adhesive composition is preferably -1.00 or greater, more preferably at least -0.85, even more preferably at least -0.75, most preferably at least -0.70.

The slope s between two peaks of the GPC curve can be as high as 0.30, preferably 0.20, more preferably 0.15.

The adhesive polyethylene composition may have a cumulative light scattering signal fraction CP at an angle of 15° above 1 million g/mol (CDSR-1M) from 7.5 to 25.0, preferably from 8.5 to 22.5 and most preferably from 10.0 up to 20.0.

The adhesive polyethylene composition may have a cumulative light scattering signal fraction CP at an angle of 15° above 2 million g/mol (CDSR-2M) from 0.1 to 10.0, preferably from 0.3 to 8.5 and most preferably from 0.4 up to 6.0.

When grafted according to the first embodiment of the temperature profile in the cylindrical section (constant temperature profile), the adhesive polyethylene composition has the following GPC properties.

The adhesive polyethylene composition preferably has a mean molecular weight Mz (CP) greater than 525,000 g/mol, for example 550,000 g/mol to 1,250,000 g/mol, preferably 600,000 g/mol to 1,100,000 g/mol, more preferably 650,000 g/mol mol to 1,000,000 g/mol, even more preferably 700,000 g/mol to 950,000 g/mol, most preferably 700,000 to 900,000 g/mol as determined by GPC-VIASC-CP analysis.

In addition, the adhesive polyethylene composition preferably has a weight average molecular weight Mw (CP) of 90,000 to 175,000 g/mol, more preferably 100,000 to 150,000 g/mol, and most preferably 117,000 to 135,000 g/mol as determined by GPC-YNAD analysis -SR.

The polydispersity index (PDI), which is the Mw/Mn ratio, of the polyethylene adhesive composition is preferably 2.5 to 8.5, more preferably 3.5 to 7.5, and most preferably 4.0 to 6.5 , when determined using GPC-VIAZK-SR analysis.

The adhesive polyethylene composition preferably has two distinct peaks and a valley between said peaks in the GPC curve. The GPC curve is defined below in the section on measurement methods as the concentration-normalized CP 15 signal to the molecular weight of conventional GPC obtained from the GPC-VIAZK-CP analysis.

The adhesive polyethylene composition preferably has a Z value of -5.0 or higher, more preferably at least -4.0, even more preferably at least -3.5, most preferably at least -3.0. The Z value can be as high as 0, preferably -0.5, more preferably -1.0.

The slope s between the two peaks of the GPC curve of the polyethylene adhesive composition is preferably -1.00 or greater, more preferably at least -0.85, even more preferably at least -0.75, most preferably at least -0.70.

The slope s between two peaks of the GPC curve can be as high as -0.30, preferably -0.50, more preferably -0.45.

The adhesive polyethylene composition may have a cumulative light scattering signal fraction CP at an angle of 15° above 1 million g/mol (CDSR-1M) from 10.0 to 25.0, preferably from 12.5 to 22.5 and most preferably from 15.0 up to 20.0.

The adhesive polyethylene composition may have a cumulative light scattering signal fraction CP at an angle of 15° above 2 million g/mol (CDSR-2M) from 1.5 to 10.0, preferably from 2.0 to 8.5 and most preferably from 2.5 up to 6.0.

The adhesive polyethylene composition may have a cumulative light scattering signal fraction CP at an angle of 15° above 3 million g/mol (CDSR-3M) from 0.1 to 7.5, preferably from 0.5 to 5.0 and most preferably from 1.0 up to 4.0.

When grafted according to the second embodiment of the temperature profile in the cylindrical section (temperature rise profile), the adhesive polyethylene composition has the following GPC properties. The adhesive polyethylene composition preferably has a z average molecular weight Mz (CP) equal to or less than 525,000 g/mol, for example from 250,000 g/ mol to 5,100,000 g/mol, preferably 300,000 g/mol to 500,000 g/mol, more preferably 350,000 g/mol to 485,000 g/mol, even more preferably 375,000 g/mol to 475,000 g/mol, most preferably 400,000 up to 460,000 g/mol when determined using GPC-VIASK-CP analysis.

In addition, the adhesive polyethylene composition preferably has a weight average molecular weight Mw (CP) of 90,000 to 175,000 g/mol, more preferably 100,000 to 150,000 g/mol, and most preferably 117,000 to 135,000 g/mol as determined by GPC-YNAD analysis -SR.

The adhesive polyethylene composition preferably has two distinct peaks and a valley between said peaks in the GPC curve. In this case, the GPC curve is defined below in the section relating to measurement methods as the concentration-normalized CP 15 signal to the molecular weight of conventional GPC, obtained from the GPC-VIASK-CP analysis.

The adhesive polyethylene composition preferably has a Z value of 0 or higher, more preferably at least 0.1, even more preferably at least 0.3, most preferably at least 0.4. The Z value can be as high as 5.0, preferably 2.5, more preferably 1.5.

The slope s between the two peaks of the GPC curve of the polyethylene adhesive composition is preferably greater than -0.30 or greater, more preferably at least -0.20, even more preferably at least -0.10, most preferably at least 0.

The slope s between two peaks of the GPC curve can be as high as 0.30, preferably 0.20, more preferably 0.15.

The adhesive polyethylene composition may have a cumulative light scattering signal fraction CP at an angle of 15° above 1 million g/mol (CDSR-1M) from 7.5 to 20.0, preferably from 8.5 to 17.5 and most preferably from 10.0 up to 15.0.

The adhesive polyethylene composition may have a cumulative light scattering signal fraction CP at an angle of 15° above 2 million g/mol (CDSR-2M) from 0.1 to 5.0, preferably from 0.3 to 3.5 and most preferably from 0.4 up to 2.0.

The adhesive polyethylene composition according to the present invention, as described above or below, is particularly suitable for producing an adhesive layer in multi-layer structures, such as, for example, a three-layer coating of a metal pipe, such as a steel pipe.

Multilayer structure

Moreover, the present invention relates to a multilayer structure including one layer containing a polyethylene adhesive composition as defined above or below.

Preferably, the multilayer structure is a pipe coating, such as a three-layer metal pipe coating. The most preferred multilayer structure is three-layer coating of steel pipe.

The layer containing the adhesive polyethylene composition as defined above or below is preferably an adhesive layer.

Preferably, the multilayer structure, more preferably a coated metal pipe, most preferably a coated steel pipe, has a peel strength at 23°C of at least 200 N/cm, more preferably 250 N/cm, even more preferably at least 275 N/cm cm and most preferably at least 300 N/cm.

The upper limit of peel strength at 23°C usually does not exceed 750 N/cm.

In addition, the multilayer structure, more preferably a coated metal pipe, most preferably a coated steel pipe, has a peel strength at 80° C. of at least 110 N/cm, more preferably at least 120 N/cm, and most preferably at least at least 150 N/cm.

The upper limit of peel strength at 80°C usually does not exceed 350 N/cm.

Herein, the multi-layer structure, more preferably a coated metal pipe, most preferably a coated steel pipe, comprising a layer which contains an adhesive polyethylene composition grafted according to the second embodiment of the temperature profile of the cylindrical section of the extruder (temperature rise profile) shows higher peel strength at 23 °C and 80°C.

In said embodiment, preferably the multilayer structure, more preferably a coated metal pipe, most preferably a coated steel pipe, has a peel strength at 23°C of at least 350 N/cm, more preferably at least 400 N/cm and most preferably at least 500 N/cm.

The upper limit of peel strength at 23°C usually does not exceed 750 N/cm.

Moreover, in said embodiment, the multilayer structure, more preferably a coated metal pipe, most preferably a coated steel pipe, has a peel strength at 80°C of at least 135 N/cm, more preferably at least 160 N/cm and most preferably at least 180 N/cm.

The upper limit of peel strength at 80°C usually does not exceed 350 N/cm.

Preferably, the multilayer structure, more preferably the coated metal pipe, most preferably the coated steel pipe, has a peel strength within the stated range regardless of the cooling procedure of the multilayer structure or the coated pipe, i.e. at normal cooling rates and at higher cooling rates.

Pipes, preferably metal pipes and most preferably steel pipes, are coated with a three-layer coating, usually in accordance with the following procedure.

It is preferable to properly prepare the pipe surface before coating, as is known in the art. The pipe surface is usually inspected for rust, dirt, imperfections, breaks in surface continuity, and metal defects. All excess material must be removed from the surface of the pipe to ensure that the coating will adhere securely to the pipe. Suitable cleaning methods include air blasting and high pressure water washing, sandblasting or shot blasting, and mechanical brushing. Acid washing and chromate pretreatment are also sometimes used.

Typically the pipes are heated by induction heating to approximately 200-220°C. The temperature is adjusted depending on the line speed and the material used in the anti-corrosion layer. When using Teknos Infralit EP8054 epoxy resin, the steel pipe is preferably heated to 190°C. During the coating process, the temperature decreases slightly.

If epoxy powder is used (at 23°C), it is usually sprayed using epoxy resin sprayers where the rotation speed of the pipe is approximately 9 m/min. The thickness of epoxy resin and other coating materials is set according to the specified end application requirements. Normal epoxy layer thickness (onshore installations) is 70 to 200 microns, eg 135 to 160 microns.

Materials that can be used in the anti-corrosion layer are, for example, epoxy resins and organosilicon compounds. Examples of suitable epoxy resins are phenol-based epoxy resins and amine-based epoxy resins. These types of epoxy resins are sold under the trade names Infralit EP8054 (from Teknos), Scotchkote 6233P (from 3M) and PE50-7191 (from BASF), among others. Suitable organosilicon compounds are described in EP-A-1 859 926.

The extrusion of the adhesive layer and the topcoat layer can be carried out, for example, using two single-screw extruders. They may have a diameter, for example, from 30 to 100 mm, for example 60 mm, and a length from 15 to 50 L/D, for example 30 L/D. The temperature is usually controlled in several zones, and the temperature of the PE adhesive material and the coating layer after the spun plate is from 190 to 300°C, for example, from 210°C to 250°C, respectively. The width of the spun plate is from 50 to 300 mm, for example 80 mm and 200 mm for the adhesive layer and the coating layer, respectively. Both the adhesive layer and the coating layer are usually rolled tightly onto the pipe using a silicone pressure roller. The thickness of the adhesive layer is usually from 200 to 600 µm, for example from 250 to 500 µm. The thickness of the coating layer is usually from 1 to 6 mm, preferably from 2 to 5 mm.

The adhesive layer preferably contains a polymer composition, preferably an adhesive polymer composition according to the present invention.

The topcoat layer preferably contains a polyethylene polymer, such as a HDPE polymer or a cross-linked polyethylene polymer, or a polypropylene polymer.

After coating, the coated pipe is cooled, for example by applying water to the surface of the coated pipe.

Examples

1.Measurement methods

a) Melt flow rate.

The melt flow index (MFI) is determined according to ISO 1133-1, method B, and is reported in g/10 min. MFR is an indicator of the fluidity and, therefore, the manufacturability of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. MFI ₂ of polyethylene is measured at a temperature of 190°C and a load of 2.16 kg. The MFR _{of 21} polyethylene is measured at a temperature of 190°C and a load of 21.6 kg.

b) Density.

The polymer density was measured according to ISO 1183-1:2004 Method A on a compression molded sample according to EN ISO 1872-2 (February 2007) and expressed in kg/m ³ .

c) Peel strength.

Peel strength refers to the relative bond strength between the epoxy layer and the adhesive layer. The peel strength of the coating compositions was measured at 23°C in accordance with ISO 21809-1:2011 using a Zwick Roell tensile testing machine with the following modifications to the method. The peel strength was recorded for three minutes and the average of the peel strength recorded over those three minutes was calculated. The average value corresponds to the presented peel strength of the composition.

d) Melting point Melting point.

Melting temperature Tm, crystallization temperature Tcr and degree of crystallinity were measured in accordance with ISO 11357 using differential scanning calorimetry (DSC) on a Mettler TA820 instrument on samples from 5 to 10 mg, typically 8 ± 0.5 mg. Both crystallization and melting curves were obtained during scanning at a rate of 10°C/min while cooling and heating from 30°C to 225°C. The peaks of endotherms and ectotherms were taken as melting and crystallization temperatures.

f) GPC measurement.

PL 220 (Agilent) GPC instrument, equipped with an infrared detector (IR4 (PolymerChar, Spain), built-in four-capillary bridge viscometer (PL-BV 400-HT) and dual light scattering detector (light scattering detector PL-LS 15/90) with angles of 15 ° and 90° Used 3 Olexis columns and 1x Olexis Guard from Agilent as stationary phase and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg/L 2,6-di-tert-butyl-4-methylphenol) in as the mobile phase at 160°C and a constant flow rate of 1 ml/min. 200 μl of the sample solution was injected for analysis.

All samples were prepared in the concentration range of 1.0-1.25 mg/ml and dissolved in 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg/l 2,6-di-tert-butyl-4-methylphenol) at 160 °C for 3 hours with continuous gentle shaking. The concentration of the injected polymer solution at 160°C (c _160°C ) was adjusted for volumetric expansion at 160°C compared to 25°C as follows:

where w ₂₅ (weight of polymer) and V ₂₅ (volume of TCB at 25°C).

Average molecular weights, polydispersity (Mn, Mw, Mz, MWD), determined using traditional GPC analysis (GPC _trad ).

For the traditional GPC approach (GPC _trad ), a set of columns was calibrated using a universal calibration (according to ISO 16014-2:2003) with 19 polystyrene (PS) standards with a narrow MWD from 0.5 kg/mol to 11500 kg/mol. PS standards were dissolved at 160°C for 15 min or alternatively at room temperature at a concentration of 0.2 mg/ml for molecular weights greater than and equal to 899 kg/mol and at a concentration of 1 mg/ml for molecular weights below 899 kg/mol. Conversion of peak maximum molecular weight of polystyrene to molecular weight of polyethylene is performed using the Marc-Houwink equation and the following Marc-Houwink constants:

K _PS =19×10 ^-3 ml/g, α _PS =0.655

K _PE =39×10 ^-3 ml/g, α _PE =0.725

A third-order polynomial fit was used to fit the calibration data.

Average molecular weights (Mz, Mw and Mn), molecular weight distribution (MWD) and its width, described by the polydispersity index, PD=Mw/Mn (where Mn is the number average molecular weight and Mw is the mass average molecular weight) were determined with using the following formulas:

GPC-VIAZK-SR analysis

For the light scattering GPC ( _LS GPC) approach, delay volumes between detectors were determined using a narrow PS standard (MWD = 1.01) with a molecular weight of 130,000 g/mol. The corresponding detector constants for the light scattering detector and the built-in viscometer were determined using the broad standard NIST1475A (Mw=52000 g/mol and IV=1.01 dl/g). The corresponding dn/dc used for the PE standard used in TCB was 0.094 cm ³ /g. The calculation was performed using Cirrus Multi-Offline SEC version 3.2 software (Agilent). The molar mass at each thin elution layer was calculated using a light scattering angle of 15°. Data collection, data processing and calculations were performed using Cirrus Multi SEC version 3.2 software. Molecular weight was calculated using the option in the Cirrus software “use CP angle 15” in the “calculation options” field, subfield “MW data from thin layer”. The dn/dc value used to determine the molecular weight was 0.094.

This molecular weight in each thin layer is calculated in the manner described by C. Jackson and H. G. Barth, "Molecular Weight Sensitive Detectors" in: Handbook of Size Exclusion Chromatography and Related Methods, CS. Wu, 2 ^nd ed ., Marcel Dekker, New York, 2004, p.103) at a low angle. For low and high molecular weight regions where less CP or RI detector signal was achieved, respectively, a linear fit was used to correlate the elution volume with the corresponding molecular weight. The linear fit region was adjusted depending on the sample.

Average molecular weights (Mz(CP), Mw(CP) and Mn(CP)), molecular weight distribution (MWD) and its width described by polydispersity, PD(CP)=Mw(CP)/Mn(CP) (where Mn(CP) is the number average molecular weight and Mw(CP) is the weight average molecular weight obtained by GPC-CP) was calculated by gel permeation chromatography (GPC) using the following formulas:

For a constant elution volume interval ΔVi, where A _i and M _i(CP) are the thin layer chromatographic peak area and the polyolefin molecular weight (MW) determined by GPC-CP.

For the average molecular weight values Mz, Mw and Mn, the polyolefin molecular weight (MW) was determined using GPC _trad , where Mz(CP), Mw(CP) and Mn(CP) mean that these average molecular weight values were obtained using the approach GPC _SR .

Calculation of the slope value (z) from the slope (s) of CP 15 and areas A and B To analyze the slope and areas of a concentration-normalized 15° light scattering detector from molecular weight determined by GPC is a useful tool for distinguishing between different production settings and recipes and especially identifying structural differences in the high molecular weight region.

To determine the slope of CP 15 and the areas A and B, the first step is to plot the normalized concentration of the light scattering detector at an angle of 15° relative to the molecular weight determined using conventional GPC. The resulting concentration-normalized CP 15 signal can then be used to calculate the slope s and areas A and B by applying the following 4 steps.

Stage 1 is to create a concentration-normalized CP chromatogram. Thus, the detector response to the CP 15 mV signal must be normalized by the concentration of the polymer solution being analyzed, which means that the detector signal is divided by the mg/mL concentration of the polymer solution obtained from the concentration detector. The normalized CP 15 signal is then plotted against the logarithmic molecular weight values in g/mol obtained by conventional GPC analysis.

The 2nd step is to calculate the slope between the concentration normalized CP 15 signal at logM(trad) 5.1 and the peak maximum of the 2nd peak of the CP 15 signal at high molecular weight (logM(trad) at 6).

The 3rd stage is to determine the line (1) To do this, the line is determined as follows.

The line parallel to the MW axis is determined by the value of y, which is identical to the value at which the CP 15 signal shows a minimum in the range of logM(trad.) between 5.1 and 6. The corresponding logM(trad.) of this point is defined as logM(min.) . The value of × ranges from 5.1 to the value of logM(trad.) at which the line intersects the CP concentration normal 15 (logM(CP)), where CP denotes the point of intersection.

The 4th stage is to determine the areas A and B (see Fig. 2).

The A+B area is defined as the area between line 1 and the concentration-normalized CP signal. Area A is the area ranging from logM(trad) 5.1 to logM(trad) logM(min), where area B is the area from logM(min) to logM(CP).

The 5th stage is to calculate the z value of the CP slope, which is determined

Where

Abs(B-A)=absolute value (B-A);

A=area between the tangent parallel to the MW axis passing through logM(min) and the CP signal 15 from a logM value of 5.1 to the logM value at which the CP signal is the minimum logM(min), in the logM range of 5 ,1 to 6;

B=area between the tangent parallel to the MW axis passing through logM(min) and the CP signal 15, from logM(min) to the point where the CP signal intersects again,

And

s is the slope between the two peaks of the GPC curve, determined at logM of 5.1 and 6.

KDSR values

The cumulative fraction of the light scattering signal at an CP angle of 15° (CDSR) is defined as the relative area above 10 ⁶ (g/mol) or, respectively, above 2*10 ⁶ (2M) and 3*10 ⁶ (3M) g/mol to the total area of the CP15 signal and calculated as follows from the normalized CP 15 signal.

where CP(15) _i represents the CP 15 signal at the corresponding conventional molecular weight.

f) Comonomer content

Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the content of 1-butene and 1-hexene comonomers in the ethylene-1-butene-1-hexene terpolymer.

Quantitative ^13C { ^1H } NMR spectra recorded in the molten state using a Bruker Avance III 500 NMR spectrometer operating at frequencies of 500.13 and 125.76 MHz for ^1H and ^13C , respectively. All spectra were recorded using a ^13C optimized 7mm magic angle spinning (MAS) probe head at 150°C using nitrogen gas for all pneumatic devices. Approximately 200 mg of material was placed in a zirconia MAS rotor with an outer diameter of 7 mm and rotated at 4 kHz. This setup was chosen primarily due to the high sensitivity required for rapid identification and accurate quantification {klimke06, parkinson07, castignolles09}. A standard single-pulse excitation was used using NOE with short recycle delays of 3 s {pollard04, klimke06} and an RS-HEPT decoupling scheme {fillip05, griffin07}. A total of 1024 (1k) transition states were obtained per spectrum.

Quantitative ^13C { ^1H } NMR spectra were processed, integrated, and the corresponding quantitative properties were determined from the integrals. All chemical shifts are internally correlated with the bulk methylene signal (8+) at 30.00 ppm {randall89}.

Characteristic signals corresponding to the incorporation of 1-butene {randall89} were observed, and the comonomer fraction was calculated as the fraction of 1-butene in the polymer relative to all monomers in the polymer.

The amount of isolated 1-butene included in the EEBEE sequences was quantified using the *B2 [I _*B2 ] center integral at 39.8 ppm, taking into account the number of reporting centers per comonomer:

B=I _*B2

In the absence of other signals indicating other comonomer sequences, i.e. observed continuous comonomer incorporation, total 1-butene comonomer content was calculated solely based on the number of isolated 1-butene sequences:

Total=V

Then the total mole fraction of 1-butene in the polymer was calculated as: fB=Total/(Etotal+Total+Htotal).

Characteristic signals corresponding to the incorporation of 1-hexene {randall89} were observed, and the comonomer fraction was calculated as the fraction of 1-hexene in the polymer relative to the total amount of monomers in the polymer.

The amount of isolated 1-hexene included in the EEEE sequences was quantified using the *B4 [I _*B4 ] center integral at 38.2 ppm, taking into account the number of reporting centers per comonomer:

Н=I* _В4

In the absence of other signals indicating other comonomer sequences, i.e. observed sequential incorporation of comonomers, the total content of 1-hexene comonomers was calculated based solely on the number of isolated 1-hexene sequences:

Ntotal=N

Then the total mole fraction of 1-hexene in the polymer was calculated as: fH=Htotal/(Etotal+Total+Htotal).

Total ethylene content was quantified using the integral of bulk methylene centers (δ+) at 30.00 ppm. This integral included the y center, as well as the 3 B4 centers of 1-hexene. Total ethylene content was calculated based on the volume integral with compensation for the observed 1-butene and 1-hexene sequences and end groups:

E=I _δ+ /2

Characteristic signals resulting from saturation of the end groups were observed. The content of such saturated end groups was quantified using the average value of the integral of the signals at 22.8 [I _2S ] and 32.2 ppm [I _3S ], assigned to the 2s- and 3s centers, respectively:

S=(1/2)*(I _2S +I _3S )

The presence of isolated comonomer units is adjusted based on the number of comonomer units and the saturated end groups present:

Etotal=E+(3/2)*B+(2/2)*H+(3/2)*S

The molar percentage of included comonomer is calculated from the mole fraction:

B[mol%]=100*fBH[mol%]=100*fH

The mass percentage of included comonomer is calculated from the mole fraction:

B[mass%]=100*(fB*56.11)/((fB*56.11)+(fH*84.16)+((1-(fB+fH))*28.05))

H[mass%]=100*(fH*84.16)/((fB*56.11)+(fH*84.16)+((1-(fB+fH))*28.05))

randall89

J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.

klimke06

Klimke, K., Parkinson, M., Piel, S., Kaminsky, W., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2006;207:382.

parkinson07

Parkinson, M., Klimke, K., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2007;208:2128.

pollard04

Pollard, M., Klimke, K., Graf, R., Spiess, H.W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004;37:813.

filip05

Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239

griffin07

Griffin, J. M., Tripon, C., Samoson, A., Filip, C., and Brown, S. P., Mag. Res. in Chem. 2007 45, S1, S198

castignolles09

Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373

Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the 1-octene comonomer content of the ethylene-1-octene copolymer.

Quantitative ^13C { ^1H } NMR spectra recorded in the molten state using a Bruker Avance III 500 NMR spectrometer operating at frequencies of 500.13 and 125.76 MHz for ^1H and ^13C , respectively. All spectra were recorded using a ^13C optimized 7mm magic angle spinning (MAS) probe head at 150°C using nitrogen gas for all pneumatic devices. Approximately 200 mg of material was placed in a zirconia MAS rotor with an outer diameter of 7 mm and rotated at 4 kHz. This setup was chosen primarily due to the high sensitivity required for rapid identification and accurate quantification {klimke06, parkinson07, castignolles09, parkinson11}. Standard single-pulse excitation was used using transient NOE with short recycle delays of 3 s {pollard04, klimke06} and RS-HEPT decoupling circuit {fillip05, griffin07}. A total of 1024 (1k) transition states per spectrum were obtained.

Quantitative ^13C { ^1H } NMR spectra were processed, integrated, and quantified using special spectral analysis automation programs. All chemical shifts are internally correlated with the bulk methylene signal (δ+) at 30.00 ppm {randall89}.

Characteristic signals corresponding to 1-octene incorporation (randall89, liu01, qiu07) were observed and all comonomer contents were calculated relative to all other monomers present in the polymer.

Characteristic signals resulting from isolated inclusion of 1-octene were observed, i.e. EEOEE comonomer sequences. Isolated 1-octene inclusion was quantified using the integral of the signal at 38.3 ppm. This integral is attributed to the unresolved signals corresponding to the *B6 and *βB6B6 centers of isolated (EEOEE) and isolated double non-consecutive (EEOOEE) 1-octene sequences, respectively. To compensate for the influence of two *РВ6 В6 centers, use the integral of the ββВ6В6 center at 24.6 ppm:

О=I _*B6+*βB6B6 -2*I _ββB6B6

When the characteristic signals resulting from successive 1-octene incorporation, that is, the comonomer sequence EOOEEE, were observed, such sequential 1-octene incorporation was quantified using the integral of the signal at 40.4 ppm attributable to the ααB6B6 center, with taking into account the number of reporting centers per comonomer:

OO=2*I _ααВ6В6

When characteristic signals resulting from isolated non-sequential inclusion of 1-octene were observed, i.e. sequence of comonomers EEOOEE, such isolated non-sequential inclusion of 1-octene was quantified using the integral of the signal at 24.6 ppm assigned to ββB6B6 centers, taking into account the number of reporting centers per comonomer:

OEO=2*I _ββB6B6

When the characteristic signals resulting from an isolated ternary successive incorporation of 1-octene were observed, i.e. comonomer sequence EOOOOOEE, this isolated triple sequential 1-octene incorporation was quantified using the integral of the signal at 41.2 ppm assigned to αγγB6B6B6 centers, taking into account the number of reporting centers per comonomer:

LLC=3/2*IαγγВ6В6В6

In the absence of other signals indicating other comonomer sequences observed, the total 1-octene comonomer content was calculated solely based on the number of isolated (EEOEE), isolated double sequential (EEOOEE), isolated non-sequential (EEOOEE) and isolated triple consecutive (EEOOOOEE) sequences of 1-octene comonomers:

O _total =O+OO+OEO+OOO

Characteristic signals resulting from saturation of the end groups were observed. Such saturated end groups were quantified using the average integral of the two resolved signals at 22.9 and 32.23 ppm. The integral at 22.84 ppm is attributed to unresolved signals corresponding to both 2B6 and 2S 1-octene centers and the saturated end of the chain, respectively. The integral at 32.2 ppm is attributed to unresolved signals corresponding to both 3B6 and 3S 1-octene centers and the saturated end of the chain, respectively. To compensate for the influence of 1-octene centers 2B6 and 3B6, the total content of 1-octene is used:

S=(1/2)*(I _2S+2B6 +I _3S+3B6 -2*O _total )

Ethylene comonomer content was quantified using the integral of the (volume) signals of bulk methylene at 30.00 ppm. This integral included the γ and 4B6 centers from 1-octene, as well as the δ+ centers. The total ethylene comonomer content was calculated based on the volume integral and taking into account the observed 1-octene sequences and end groups:

E _total =(1/2)*[I _volume +2*O+1*OO+3*OEO+0*OOO+3*S]

It should be noted that compensation of the volume integral for the presence of isolated triple inclusion sequences (EEOOOOEE) of 1-octene is not required, since the number of undercounted and overcounted ethylene units is the same.

The total mole fraction of 1-octene in the polymer was then calculated as:

fO=O _total /(E _total +O _total )

The total incorporation of 1-octene comonomer in mass percent was calculated from the mole fraction using the standard method:

О[wt%]=100*(fO*112.21)/((fO* 112.21)+((1-fO)*28.05))

klimke06

Klimke, K., Parkinson, M., Piel, S., Kaminsky, W., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2006;207:382.

parkinson07

Parkinson, M., Klimke, K., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2007;208:2128. parkinson11

NMR Spectroscopy of Polymers: Innovative Strategies for Complex Macromolecules, Chapter 24, 401 (2011)

pollard04

Pollard, M., Klimke, K., Graf, R., Spiess, H.W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004;37:813.

filip05

Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239

griffin07

Griffin, J. M., Tripon, C., Samoson, A., Filip, C., and Brown, S. P., Mag. Res. in Chem. 2007 45, S1, S198

castignolles09

Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373

zhou07

Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, V., J. Mag. Reason. 187 (2007) 225

busico07

Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128

randall89

J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.

qui07

Qiu, X., Redwine, D., Gobbi, G., Nuamthanom, A., Rinaldi, P., Macromolecules 2007, 40, 6879

liu01

Liu, W., Rinaldi, P., Mcintosh, L., Quirk, P., Macromolecules 2001, 34, 4757.

Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the acrylate comonomer content of the ethylene butyl acrylate elastomer.

Quantitative ¹ H NMR spectra were recorded in the molten state using a Bruker Avance III 500 NMR spectrometer operating at a frequency of 500.13 MHz. All spectra were recorded using a ^13C optimized 7mm magic angle spinning (MAS) probe head at 150°C using nitrogen gas for all pneumatic devices. Approximately 200 mg of material was placed in a zirconia MAS rotor with an outer diameter of 7 mm and rotated at 4 kHz. This setup was chosen primarily due to the high sensitivity required for rapid identification and accurate quantification {klimke06, parkinson07, castignolles09}. We used standard single-pulse excitation with a recycle delay of 2 s {pollard04, klimke06}. A total of 64 transition states were obtained for each spectrum.

Quantitative ^1H NMR spectra were processed, integrated, and quantified using special spectral analysis automation programs. All chemical shifts are internally correlated with the bulk ethylene methylene signal at 1.33 ppm.

Attribution of butyl acrylate (BA) inclusion to {brandolini01}:

Butyl acrylate (BA) incorporation was quantified using the integral of the signal at 4.06 ppm assigned to 4BA sites, taking into account the number of reporting sites per comonomer:

VA=I _4BA /2

Ethylene content was quantified using the integral of the volumetric aliphatic signal (I _volume ) in the range of 0.00–3.00 ppm. This integral includes the 1BA (3), 2BA (2), 3BA (2), *BA (1) and αBA (2) centers from the isolated butyl acrylate inclusion, as well as centers from polyethylene sequences. The total ethylene content was calculated based on the volume integral and with compensation for the above VA centers:

E=(1/4)*[I _volume -10*VA]

The total mole fractions of butyl acrylate (BA) in the polymer were calculated as:

fBA=BA/(E+BA)

The total incorporation of butyl acrylate (BA) comonomer in mole percent was calculated from the mole fractions using the standard method:

VA[mol.%]=100*fBA

The total inclusion of butyl acrylate (BA) comonomer in mass percent was calculated from the mole fractions and molecular weight of the monomers in a standard way:

VA[mass%]=100*(fBA*128.17)/((fBA*128.17)+(1-fBA)*28.05))

klimke06

Klimke, K., Parkinson, M., Piel, S., Kaminsky, W., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2006;207:382.

parkinson07

Parkinson, M., Klimke, K., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2007;208:2128.

pollard04

Pollard, M., Klimke, K., Graf, R., Spiess, H.W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004;37:813.

castignolles09

Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373

brandolini01

A.J. Brandolini, D.D. Hills, "NMR spectra of polymers and polymer additives", Marcel Deker Inc., 2000.

g) Quantification of unsaturated bonds using NMR spectroscopy.

Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the content of unsaturated groups present in the polymers.

Quantitative ¹ H NMR spectra were recorded in the dissolved state using a Bruker Avance III 400 NMR spectrometer operating at a frequency of 400.15 MHz. All spectra were recorded using a ^13C optimized 10mm selective excitation head at 125°C using nitrogen gas for all pneumatic devices. Approximately 200 mg of material was dissolved in 1,2-tetrachloroethane-d2 (TCE-d2) using approximately 3 mg of Hostanox 03 (CAS 32509-66-3) as a stabilizer. Standard single-pulse excitation was used using a 30° pulse, a relaxation delay of 10 s, and a sample rotation of 10 Hz. A total of 128 transition states were obtained per spectrum using 4 model scans. This setup was chosen primarily due to the high resolution required for quantification of unsaturations and stability of vinylidene groups {he10a, busico05a}. All chemical shifts were indirectly referred to TMS at 0.00 ppm using the signal obtained from the residual protonated solvent at 5.95 ppm.

Characteristic signals corresponding to the presence of terminal aliphatic vinyl groups (R-CH=CH2) were observed and the quantity was determined using the integral of the two bound nonequivalent terminal CH ₂ protons (Va and Vb) at 4.95, 4.98 and 5.00 and 5 .05 ppm taking into account the number of reporting centers per functional group:

Nvinyl=IVab/2

When characteristic signals consistent with the presence of internal vinylidene groups (RR'C=CH2) were observed, their quantity was determined using the integral of the two _CH2 protons (D) at 4.74 ppm, taking into account the number of reporting sites per functional group:

Nvinylidene=ID/2

When characteristic signals consistent with the presence of internal cis-vinylene groups (E-RCH=CHR') or related structure were observed, the amount was determined using the integral of the two CH(C) protons at 5.39 ppm, taking into account the number of reporting sites per functional group:

Ncis=IC/2

When characteristic signals corresponding to the presence of internal trans-vinylene groups (Z-RCH=CHR') were observed, their quantity was determined using the integral of two CH(T) protons at 5.45 ppm, taking into account the number of reporting sites per functional group:

Ntrans=IT/2

When characteristic signals corresponding to the presence of internal trisubstituted vinylene groups (RCH=CHR'R'') or related structure were observed, their quantity was determined using the CH proton integral (Tris) at 5.14 ppm, taking into account the number of reporting sites per functional group:

Ntris=ITris

Hostanox 03 stabilizer was quantified using the multiplet integral of aromatic protons (A) at 6.92, 6.91, 6.90 and 6.89 ppm and taking into account the number of reporting sites per molecule:

H=IA/4

As is typical for the quantification of unsaturated bonds in polyolefins, the degree of unsaturation was determined relative to the total number of carbon atoms, although quantified using ¹ H NMR spectroscopy. This allows direct comparison with other microstructure values obtained directly from ¹³ C NMR spectroscopy.

The total number of carbon atoms was calculated from the integral of the bulk aliphatic signal between 2.85 and -1.00 ppm, compensating for methyl signals from the stabilizer and carbon atoms related to unsaturated functionality not included in this scope:

NCtotal = (Ivolume-42*H)/2+2*Nvinyl+2*Nvinylidene+2*Ncis+2*Ntrans+2*Ntris

The content of unsaturated groups (U) was calculated as the number of unsaturated groups in the polymer per thousand total carbon atoms (kCHn):

U=1000*N/NCtot.

The total number of unsaturated groups was calculated as the sum of the individual observed unsaturated groups and thus also presented per thousand total carbon atoms:

Utotal=Uvinyl+Uvinylidene+Ucis+Utrans+Utris

The relative content of a particular unsaturated group (U) is indicated as the proportion or percentage of that unsaturated group relative to the total amount of unsaturated groups:

[U]=Ux/Utot.

Bibliography

he10a

Nie, Y., Qiu, X., and Zhou, Z., Mag. Res. Chem. 2010, 48, 537-542.

busico05a

Busico, V. et al. Macromolecules, 2005, 38(16), 6988-6996.

h) Rheological parameters Characterization of polymer melts using dynamic shear measurements is in accordance with ISO standards 6721-1 and 6721-10. Measurements were performed on an Anton Paar MCR501 stress-controlled rotational rheometer equipped with a 25 mm parallel plate geometry. The measurements were carried out on plates obtained by pressing, in a nitrogen atmosphere and when the deformation was established in the linear viscoelastic regime. Oscillatory shear tests were performed at 190°C using a frequency range from 0.01 to 600 rad/s and a gap setting of 1.3 mm. In a dynamic shear experiment, the probe is subjected to uniform deformation under a sinusoidal variable shear strain or shear stress (controlled strain and stress mode, respectively). In a strain-controlled experiment, the probe is subjected to a sinusoidal strain, which can be expressed as

If the applied strain is within the linear viscoelastic regime, the resulting sinusoidal stress response can be given by

where σ ₀ and γ ₀ represent the stress and strain amplitudes, respectively; ω represents the angular frequency; δ represents the phase shift (loss angle between the applied strain and the stress response); t represents time.

The results of dynamic tests are usually expressed using several different rheological functions, namely dynamic shear modulus G', shear loss modulus G'', complex shear modulus G*, complex shear viscosity η*, dynamic shear viscosity η' non-synchronous component of complex shear viscosity η'' and loss tangent tan η, which can be expressed as follows:

Determination of the so-called shear thinning index, which correlates with MWD and is independent of Mw, is performed as described in equation 9.

For example, PRS _(2.7/210) is determined by the complex viscosity in Pa⋅s determined for a G* value of 2.7 kPa divided by the complex viscosity in Pa⋅s determined for a G* value of 210 kPa .

Accordingly, the ORV _(1/100) is determined by the complex viscosity value, in Pa⋅c, determined at a G* value of 1 kPa, divided by the complex viscosity value, in Pa⋅c, determined at a G* value equal to 100 kPa.

The values of dynamic elastic modulus (G'), loss modulus (G''), complex modulus (G*) and complex viscosity (η*) were obtained as a function of frequency (ω).

In this case, for example, η* _{300 rad/s} (eta* _{300 rad/s} ) is used as an abbreviation for complex viscosity at a frequency of 300 rad/s, and η* _{0.05 rad/s} (eta* _{0.05 rad/s} ) is used as an abbreviation designation of complex viscosity at a frequency of 0.05 rad/s.

The loss tangent tan (delta) is defined as the ratio of the loss modulus (G'') and the dynamic modulus of elasticity (G') at a given frequency. In this case, for example, tan _0.05 is used as an abbreviation for the ratio of the loss modulus (G'') and the dynamic modulus of elasticity (G) at 0.05 rad/s, and tan ₃₀₀ is used as an abbreviation for the ratio of the loss modulus (G'' ) and dynamic modulus of elasticity (G') at 300 rad/s.

The elasticity balance tan _0.05 /tan ₃₀₀ is defined as the ratio of the loss tangent tan _0.05 and the loss tangent tan ₃₀₀ .

In addition to the rheological functions mentioned above, it is also possible to determine other rheological parameters, such as the so-called elasticity index PE(x). The elasticity index PE(x) is the value of the dynamic modulus of elasticity G', determined for the value of the loss modulus G'' for x kPa, and can be described by equation 10.

For example, PE(5 kPa) is determined by the value of the dynamic modulus of elasticity G', determined for a value of G'' equal to 5 kPa, PE(2 kPa) is determined by the value of the dynamic modulus of elasticity G', determined for a value of G'' equal to 2 kPa, and PE(0.5 kPa) is determined by the value of the dynamic modulus of elasticity G, determined for a value of G'' equal to 0.5 kPa.

The polydispersity index of PP is determined by equation 11.

where ω _ср represents the cross angular frequency, defined as the angular frequency for which the dynamic modulus of elasticity G' is equal to the loss modulus G''.

The values are determined using a single point interpolation procedure as defined by the Rheoplus software. In situations where a given value of G* is not achieved experimentally, the value is determined by extrapolation using the same procedure as before. In both cases (interpolation or extrapolation), the Rheoplus option “Interpolate y values into x values from parameter” and “logarithmic interpolation type” were used.

Bibliography

[1] "Rheological characterization of polyethylene fractions", Heino, EX., Lehtinen, A., Tanner J., Seppala, J., Neste Oy, Porvoo, Finland, Theor. Appl. Rheol., Proc. Int. Congr. Rheol, 11th (1992), 1, 360-362.

[2] "The influence of molecular structure on some rheological properties of polyethylene", Heino, E.L., Borealis Polymers Oy, Porvoo, Finland, Annual Transactions of the Nordic Rheology Society, 1995.

[3] "Definition of terms relating to the non-ultimate mechanical properties of polymers", Pure & Appl. Chem., Vol.70, No. 3, pp.701-754, 1998.

i) Dynamic Mechanical Thermal Analysis (DMTA) The elastic modulus G' and glass transition temperature Tg were measured using DMTA. Evaluation of DMTA and measurement of the dynamic modulus of elasticity G' was carried out in torsion mode on samples obtained by pressing at temperatures from -130°C to +150°C at a heating rate of 2°C/min and a frequency of 1 Hz in accordance with ISO 6721-02 and ISO 6721-07. The measurements were carried out on an Anton Paar MCR 301 instrument. The pressed samples have the following dimensions: 40x10x1 mm and are manufactured in accordance with ISO 1872 2:2007. The elastic modulus G' 23 was measured at 23°C.

2. Components of the polymer composition For the manufacture of polymer compositions of the examples, the following components were used: PE1:

A ternary copolymer of ethylene, 1-butene and 1-hexene was polymerized in a sequential multi-stage loop reactor followed by a gas phase reactor using a single site metal polymerization catalyst prepared as follows.

130 g of metallocene complex bis(1-methyl-3-n-butylcyclopentadienyl) zirconium(IV) dichloride (CAS No. 151840-68-5) and 9.67 kg of a 30% solution of commercially available methylaluminoxane (MAO) in toluene were combined and added 3.18 kg of dry purified toluene. The complex solution thus obtained was applied to 17 kg of Sylopol 55 SJ silica carrier (supplied by Grace) by very slow, uniform spraying over 2 hours. The temperature was maintained below 30°C. The mixture was reacted for 3 hours after adding the complex at 30°C.

The loop reactor was operated at a temperature of 85°C and a pressure of 6.4 MPa (64 bar). Ethylene was introduced into the reactor along with the 1-butene-hydrogen comonomer and catalyst such that the molar ratio of hydrogen to ethylene was 0.2 mol/kmol and the ratio of 1-butene to ethylene was 98.4 mol/kmol.

The suspension was periodically withdrawn from the loop reactor using settling branches and sent to a flash vessel operated at a temperature of 50°C and a pressure of 0.3 MPa (3 bar). From there, the polymer was sent to a gas-phase reactor (GPR), operated at a pressure of 2 MPa (20 bar) and a temperature of 75°C. Ethylene was introduced into the reactor along with the comonomer 1-hexene and hydrogen such that the molar ratio of hydrogen to ethylene was 0.4 mol/kmol and the ratio of 1-hexene to ethylene was 12.2 mol/kmol.

The polymerization conditions and properties of the PE1 polymer are shown in Tables 2 and 3 below.

PE2: Ethylene-1-octene copolymer was polymerized in a solution polymerization process using a Ziegler-Natta catalyst as described in Example III of WO 95/09191 A. The catalyst/donor feed into the reactor (on average) was BOMAG, SEAC, TBT. The catalyst/donor feed into the reactor (on average) was BOMAG, SEAC, TBT, 2-chlorobutane and TEA as activator. The resulting copolymer has a density of 935 kg/m ³ , MTRg of 7.3 g/10 min and a melting point Tm 124°C.

The polymerization conditions and polymer properties are shown in Tables 1 and 3 below.

EBA: Ethylene butyl acrylate elastomer having a butyl acrylate content of 27 wt. %, density 927 kg/m ³ and MFR value ₂ 4 g/10 min.

The properties of EBA are shown in Table 3 below.

MAN: Maleic anhydride was used as an acid grafting agent.

POX: Perkadox 14S-fl supplied by Akzo Nobel (10 wt% dissolved in isododecane) was used as the radical initiator.

The following feed amounts of components shown in Table 4 were used to prepare the adhesive resin components in the examples.

3. Compounding and Grafting of the Example Polymer Compositions The Example polymer compositions were compounded and grafted in a Werner & Pfleiderer ZSK 30 parallel rotating twin screw extruder having an L/D 38 with 6 temperature control sections.

Example IE2 of the invention differs from Example IE1 of the invention only by compounding the composition using a temperature profile in the control zones of the extruder, starting with a lower temperature of 160°C in control zone 1 and gradually increasing the temperature to 200°C in control zone 4. The temperature was then slightly increased in subsequent control zones to a temperature of 210° C. in control zone 6 and on the spun plate. The composition of Inventive Example IE1 and Comparative Example CE1 was compounded using a uniform temperature profile at approximately 200°C in control zones 2-6 and on the die plate, starting at a temperature of 180°C in control zone 1.

For the examples, the following mixing conditions were used, and the following properties of the resulting polyethylene adhesive compositions were obtained, shown below in Table 5.

The polymer compositions of Examples CE1, IE1 and IE2 prepared above were subjected to GPC measurements and GPC-VIASC-CP analysis. Figure 1 shows the CP signal 15 obtained from GPC-VIASC-CP analysis of examples CE1, IE1 and IE2.

The different grafting processes in Examples IE1 and IE2 of the invention result in different grafting patterns, which can be identified by GPC-VIASC-SR in FIG. 1. Example IE1 of the invention shows a higher first peak on the left side (lower Mw) with increased area A under said peak and a lower second peak on the right side (higher Mw) with reduced area B under said peak. Compared to inventive example IE1, inventive example IE2 shows a more uniform distribution of the two areas A and B. These differences are believed to result from the higher proportion of low molecular weight compound in the polymer composition of inventive example. Both examples IE1 and IE2 of the invention exhibit a lower second peak on the right side with a reduced area B compared to that of comparative example CE1.

From the CP 15 signal obtained from the GPC-VIASC-CP analysis of examples CE1, IE1 and IE2, the Z values are calculated by obtaining the areas A and B and the slope s between the first and second peaks from the resulting CP 15 signal from the GPC-VIASC-CP analysis . The Z values and slope are given in Table 5 below.

In the GPC curve in FIG. 2, a shift towards higher weight average molecular weights can be observed for examples IE1 and IE2 of the invention compared to CE1. The molecular weights of Mw, Mn, Mz and PPD (Mw/Mn) are given in Table 5 below.

4. Pipe coating

The resin compositions prepared as described above were used as adhesive resin compositions in adhesive layers in a three-layer pipe coating.

First, steel pipes with a diameter of 114.3 mm and a wall thickness of 5 mm were heated in a rotating steel pipeline at a line speed of 9 m/min to a temperature of 200-220°C and sprayed with epoxy powder as corrosion protection. The polymer compositions prepared above and conventional high-density polyethylene were then co-extruded onto an epoxy layer as an adhesive layer and outer protective layer. Co-extrusion was carried out using a KM-45 single-screw extruder for the high-density polyethylene topcoat and an Extron 50 single-screw extruder for the polymer compositions prepared above. The temperature at the extruder head of the polymer compositions was 215°C. The temperature at the extruder head of the high density polyethylene composition was 215°C.

The following layer thicknesses were chosen:

Epoxy layer: 150 microns

Adhesive layer: 480 microns

Protective outer layer: 4.2 mm

Both the adhesive layer and the protective outer layer were pressed tightly onto the coating surface using a silicone pressure roller.

The coated pipes were subjected to two different cooling procedures as described below in Table 6.

In both cooling procedures, the coated pipe is subjected to a water cooling step in which the pipe is cooled in a water spray chamber until it reaches a target temperature of about 40°C for normal cooling and about 85°C for short-term cooling. Compared to the conventional cooling procedure, in the short-term cooling procedure the water cooling step is significantly reduced until the pipe reaches a temperature of approximately 85°C instead of approximately 40°C in the conventional cooling procedure to simulate higher line speeds in the cooling bath. Instead, the coated pipe is removed from the water spray chamber and allowed to cool from about 80° C. to about 23° C. in ambient air, which takes about 90-120 minutes. In the conventional cooling step, the pipe that was cooled in the water cooling step to a temperature of about 40° C. is also removed from the water spray chamber and allowed to cool from about 40° C. to about 23° C. in ambient air.

After cooling, the pipe coatings were subjected to peel strength tests at 23°C. The results are presented below in Table 7.

It can be seen that coatings comprising adhesive layers made from the polymer compositions of the present invention IE1 and IE2 exhibit higher peel strength after both normal and short-term cooling procedures at 80°C compared to coatings including adhesive layers made from a comparative polymer composition CE1 using ethylene-1-octene copolymer instead of ethylene-1-butene-1-hexene terpolymer as the non-elastomeric polyethylene.

Moreover, the composition IE2 according to the invention shows particularly high peel strength at 23°C and 80°C after a short-term cooling procedure, almost no difference from the peel strength after a conventional cooling procedure.

Thus, the polymer compositions obtained in accordance with the present invention satisfy the requirements of ISO 21809-1:2011, class C, with regard to peel strength measurements at 23°C and 80°C, also after a short-term cooling procedure.

Claims (26)

1. Adhesive polyethylene composition, suitable for multi-layer structures, containing (A) from 60 to 90 wt. % non-elastomeric polyethylene, which is a ternary copolymer of ethylene with two different alpha-olefins having from 4 to 12 carbon atoms; (B) from 9.0 to 38 wt. % elastomer; wherein component (A) or components (A) and (B) are grafted with an acid grafting agent (C) in an amount from 0.01 to 3.0 wt. %, all based on the total weight of the adhesive polyethylene composition. 2. The adhesive polyethylene composition according to claim 1, in which the non-elastomeric polyethylene is a ternary copolymer of ethylene with 1-butene and 1-hexene. 3. The adhesive polyethylene composition according to claim 1, in which the elastomer (B) is a copolymer of ethylene with polar comonomer units, where the number of polar comonomer units is from 15 to 40 wt. %. 4. The adhesive polyethylene composition according to claim 1, wherein the acid grafting agent (C) is selected from unsaturated carboxylic acids or derivatives thereof, such as anhydrides, esters and metallic or non-metallic salts. 5. An adhesive polyethylene composition according to claim 1, having a melt flow index PTR ₂ (190°C, 2.16 kg) from 0.1 to 10.0 g/10 min and/or a density from 900 kg/m ³ to 960 kg/ ^m3 . 6. An adhesive polyethylene composition according to claim 1, having a rheological polydispersity index of PP less than 1.50. 7. The adhesive polyethylene composition according to claim 1, having a weight average molecular weight Mw (CP) of 90,000 g/mol to 175,000 g/mol, determined by GPC-VIASC-CP analysis. 8. The adhesive polyethylene composition according to claim 1, having a z-value from -5.0 to 5.0 and/or a slope from -1.00 to 0.30 when measuring GPC, where the GPC curve is defined as the concentration of the normalized SP 15 signal according to molecular weight of traditional GPC obtained from GPC-VIASK-CP analysis. 9. An adhesive polyethylene composition according to claim 1, obtained by a method including the stages - feeding components (A), (B) and (C) into the extruder into a feed section of an extruder comprising a feed section, a cylindrical section and a die plate, wherein the cylindrical section of the extruder is downstream of the feed section and upstream of the die plate, divided into a plurality of control zones, and the first control zone is a first control zone within a cylindrical section downstream of the loading zone in which the feed component or components (A) and/or (B) begin to melt; - compounding components (A) and (B) in an extruder to obtain an adhesive polyethylene composition and - grafting component (A) or components (A) and (B) with component (C) during the compounding step. 10. The adhesive polyethylene composition according to claim 9, where the temperature from the second to the last control zone in the cylindrical section is maintained constant across all these control zones with a total deviation of no more than 20°C and the adhesive polyethylene composition has an average molecular weight Mz (CP) of more than 525,000 g/mol determined by GPC-VIASK-SR analysis, and/or a z value of -5.0 to 5.0 and/or a slope of -1.00 to -0.30 by GPC measurement, where the GPC curve is defined as the concentration of the normalized CP 15 signal to the molecular weight of conventional GPC, obtained from the GPC-VIASK-CP analysis. 11. Adhesive polyethylene composition according to claim 9, where the method additionally includes the stages - independent temperature control of each control zone from the plurality of control zones of the cylindrical section of the extruder so that a) the temperature in the first control zone of the cylindrical section after the loading section is from more than 85°C to 180°C, b) the temperature of the control zones of the cylindrical section from the first control zone of the cylindrical section downstream of the loading section to the control zone in the middle of the cylindrical section is increased along the length of the cylindrical section in two or more stages so that the temperature of the control zone in the middle of the cylindrical section is between 105% up to 145% of the temperature in the first control zone of the cylindrical section downstream of the loading section, and c) the temperature of the control zones of the cylindrical section from the control zone in the middle of the cylindrical section to the control zone of the cylindrical section immediately upstream of the spun plate is maintained at the same level or increased to a temperature of not more than 120% of the temperature of the control zone in the middle of the cylindrical section, and the adhesive polyethylene composition has a z-average molecular weight Mz (CP) equal to or less than 525,000 g/mol, determined by GPC-VYAZK-CP analysis, and/or a z-value of greater than 0 to 5.0 and/or a slope of greater than - 0.30 to 0.30 in GPC measurement, where the GPC curve is defined as the concentration of the normalized CP 15 signal over the molecular weight of conventional GPC, obtained from the GPC-VIASK-CP analysis. 12. Multilayer structure containing one layer including an adhesive polyethylene composition according to any one of paragraphs. 1-11. 13. Multilayer structure according to claim 12, which is a three-layer coating of a metal pipe. 14. Multilayer structure according to claim 12 or 13, having a peel strength at 23°C of at least 200 N/cm and/or a peel strength at 80°C of at least 110 N/cm. 15. Use of an adhesive polyethylene composition according to any one of paragraphs. 1-11 to obtain a multilayer structure.

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