WO2020096475A1

WO2020096475A1 - Adhesive polyethylene composition, process for manufacturing and use of the same

Info

Publication number: WO2020096475A1
Application number: PCT/RU2018/000725
Authority: WO
Inventors: Alexey Mikhailovich VOLKOV; Irina Gennadievna RYZHIKOVA; Nikolay Alexandrovich BAUMAN
Original assignee: Public Joint Stock Company "Sibur Holding"
Priority date: 2018-11-06
Filing date: 2018-11-06
Publication date: 2020-05-14

Abstract

The present invention relates to an adhesive polyethylene composition for use as an adhesive layer in multilayer articles. The adhesive composition according to the invention comprises, relative to its total weight: A) from 59.9 to 81.2 wt.% of a linear low-density polyethylene (LLDPE) having a density in the range from 0.915 to 0.925 g/cm³ and characterised by a branched hydrocarbon chain with side branches comprising at least 4 carbon atoms; B) from 15 to 20 wt.% of a high-density polyethylene (HDPE) grafted with a functional monomer having a density of at least 0.955 g/cm³; C) from 3 to 20 wt.% of an elastomer; D) up to 100% of optional additives, wherein the LLDPE and the HDPE have an MFI_190/2.16 in the range from 0.8 to 1.2 g/10 min. The composition is manufactured by blending and processing the components into a homogeneous melt using mixing equipment and an extruder. The so-obtained adhesive composition has high peel strength, including at elevated temperatures. The invention also relates to use of the adhesive polyethylene composition as an adhesive layer in multilayer coatings, in particular, as multilayer insulation of tubes for constructing main gas- and oil pipelines.

Description

ADHESIVE POLYETHYLENE COMPOSITION, PROCESS FOR MANUFACTURING AND USE OF THE SAME

Field of the invention

The present invention relates to an adhesive polyethylene composition for use as an adhesive layer to be coated onto various metal surfaces to provide anticorrosive protection, and to a process for manufacturing said composition. In particular, the adhesive compositions of the present invention are used for insulating tubes, in construction of main gas- and oil pipelines. In addition to tube insulation, the compositions of the present invention are useful as an adhesive layer in other multilayer systems, for example, in coatings, films, plastics, and ceramics.

Prior art

Patent US 6855432, 03.08.1990, [1], discloses polyethylene compositions that are suitable as adhesive coatings. For instance, patent [1] discloses such a composition used as an adhesive layer between a metal and a polymer, comprising polyethylene or its copolymers with a-olefms. The known composition comprises: (A) 20 to 60 parts by weight of polyethylene; (B) 10 to 30 parts by weight of maleic anhydride grafted polyethylene; (C) 10 to 35 parts by weight of high impact polystyrene; (D) 10 to 25 parts by weight of an elastomer. US 6855432 teaches using polymer components grafted with various functional monomers in the composition so as to achieve higher bind strength and to produce such polymer components by means of catalysts of different nature. The peel strength range achievable in [1] is from 16.4 to 36.3 N/mm.

Patent RU 2265618, 10.01.2002, [2], discloses a composition suitable for multilayer coatings of metals, glass, plastic, and ceramics. The known composition has a multi-component formulation based on polyethylene or its copolymers with a-olefms, and comprises: A) a copolymer of ethylene and acrylic acid and/or a terpolymer of ethylene, acrylic acid and acrylic acid ether in an amount from 10 to 50 wt.%, relative to the total weight of the mixture; B) a copolymer of ethylene with an a-olefm in an amount from 50 to 90 wt.%, relative to the total weight of the mixture; C) ethylenically unsaturated dicarboxylic acids and/or anhydrides thereof. The known invention is directed to the use of polymer components grafted with various functional monomers in the composition to achieve higher peel strength and to obtain such polymer components using catalysts of different nature. The technical result of the invention described in [2] is peel strength of 27.5 N/mm at 23°C and 25 N/mm at 80°C; said technical result is achievable through grafting two components A) and B) of the composition with maleic anhydride in a single step.

Patent EA 007577, 29.12.2006, [3], discloses a multi-component polyethylene composition suitable for various uses, in particular, for insulation of metal tubes, the composition having the following formulation: A) a non-elastomeric polyethylene comprising from 40 to 97 wt.% of the total weight of the composition, and B) an elastomer comprising an elastomeric copolymer of ethylene with polar comonomer moieties, wherein the component A) or the components A) and B) are grafted using a functional monomer (modifier). The composition disclosed in [3] provides for use of polymer components grafted with various functional monomers in the composition to achieve higher peel strength and to obtain such polymer components using catalysts of different nature. The engineering solution described in [3] ensures peel strength in wide temperature ranges, for example, it is equal to 46.8 N/mm at 23°C, 22.2 N/mm at 70°C, 13.1 N/mm at 85°C, and 9.5 - 6 N/mm at 95-lOO°C. Said peel strength values are obtained by manufacturing a maleic anhydride grafted polyethylene on a catalyst with one active site, particularly, when a metallocene component on a porous support is used as the catalyst.

Adhesive compositions used as coatings perform a protective function; a number of requirements are imposed thereupon; first and foremost, they must provide the firmest adherence of the composition to a surface of a protected material. Firm adherence as a property may be characterised by peel strength, i.e. tearing strength of a specific material, in particular, steel within the framework of the present invention. It should be noted that said peel strength values do not suffice to protect metal surfaces from mechanical damages and corrosion in a wide range of temperatures, especially from 23°C to 80°C.

As evident from the prior art, it is a conventionally accepted practice to modify polyethylene with maleic anhydride, which latter is employed virtually in all modem adhesive compositions. It is used both as a finished maleinized product, for example, Polybond 3009 (US 5637410, [4], WO 9509212, [5]), and is prepared immediately prior to use by grafting maleic anhydride to polyethylenes of various grades during a two-step process for manufacturing an adhesive composition. The concentration of a maleic anhydride grafted polyethylene has a considerable effect on composition properties. Prior art references [l]-[5] require lowering the concentration of the maleic anhydride grafted polyethylene both from the viewpoint of economic attractiveness of such a composition, and from the viewpoint of reducing the concentration of toxic maleic anhydride in the composition. For instance, in patent RU 2265618 [2], the concentration of polymers grafted with functional monomers is from 0.05 to 0.15 wt.%, relative to the total weight of the components. However, none of the references [l]-[5] sheds light on a relationship between the reduction in the concentration of the maleic anhydride grafted polymer and the peel strength.

Patent US 8247053, [6], which was selected as a prototype of the present invention, is the closest in terms of technical essence and discloses an adhesive polyethylene composition comprising from 1 to 40 wt.% of polyethylene or its copolymers with a-olefms (component A) grafted with a functional monomer, or a blend of polyethylene (component Al) with a second polymer (component A2) different from Al, in which the components Al and A2 are co-grafted with an unsaturated polar monomer selected from unsaturated carboxylic acids and anhydrides thereof. The content of the unsaturated polar monomer is from 0 to 10,000 parts per million (ppm). The composition described in [6] comprises from 25 to 98 wt.% of a non-grafted polyethylene (component B) obtained by metallocene catalysis, having a density in the range from 0.910 to 0.930 g/cm³, from 1 to 35 wt.% of an elastomeric product (component C), which is either a copolymer of ethylene with a-olefms having a density in the range of 0.860 to 0.900 g/cm³, or ethylene-alkyl(meth)acrylate copolymers or ethylene-alkyl(meth)acrylates-maleic anhydride terpolymers, and a peroxide.

Patent [6] also discloses that lubricant additives are used to improve processability of the adhesive polyethylene composition. Stearamide, oleamide, erucinamide, calcium stearate, zinc stearate, aluminium stearate, magnesium stearate, and polyethylene wax in an amount from 0.01 to 1 wt.% are mentioned as said lubricants.

The process for manufacturing the adhesive composition according to US 8247053 is a two-step process, comprising a step of blending and modifying one or more of polyethylenes A, then diluting the resulting blend with polymers B and the component C. The blending takes place in a twin-screw extruder. The so-obtained known composition is useful as an adhesive layer in epoxy-coated metal tubes for their protection from corrosion.

The disadvantageous feature of the composition described in [6] is insufficiently high peel strength values, not more than 37 N/mm. In addition, the process for making the non-grafted polyethylene component (component B) of the known composition is limited, particularly, by use of a metallocene catalyst.

There is therefore a need to provide an adhesive polyethylene composition having high peel strength, both at normal and elevated temperatures.

It is an object of the present invention to provide an adhesive polyethylene composition having high peel strength, including at elevated temperatures.

The technical result of the present invention is improvement of the peel strength of the polyethylene composition, particularly, improvement of the peel strength to steel to the range from 41 to 62 N/mm at 23°C, to the range from 20 to 45 N/mm at 60°C, to the range from 15 to 25 N/mm at 80°C. A further technical result is a decrease in the concentration of the functional monomer grafted polyethylene used in the composition, which is economically attractive.

What is essential for the achievement of the technical result of the present invention is: 1) density values of polyethylenes used in the compositions; 2) MFI of polyethylenes, and 3) the branched structure of the hydrocarbon chain of a linear low- density polyethylene (LLDPE). Said technical result can be achieved by using in the composition a binary blend of polyethylenes consisting of a linear low-density polyethylene (LLDPE) and a high-density polyethylene (HDPE) that considerably differ from one another by density and are characterized by melt flow indices (MFI190_/2_.16) in the range from 0.8 to 1.2 g/lO min.

The authors of the present invention have surprisingly discovered that the peel strength of the composition improves greatly due to use of a linear low-density polyethylene characterised by a branched hydrocarbon chain with side branches comprising at least 4 carbon atoms. At that, the best technical result is achieved from using an LLDPE characterised by the presence of long-chain branches of hydrocarbon chains, i.e. side branches comprising 100 or more carbon atoms.

Detailed description of the invention The adhesive composition according to the present invention comprises the following components, relative to its total weight:

A) from 59 to 82 wt.% of a linear low-density polyethylene (LLDPE), having a density in the range from 0.915 to 0.925 g/cm³ and characterised by a branched hydrocarbon chain with side branches comprising at least 4 carbon atoms;

B) from 15 to 20 wt.% of a high-density polyethylene (HDPE) grafted with a functional monomer, having a density of at least 0.955 g/cm³;

C) from 3 to 20 wt.% of an elastomer,

D) up to 100% of optional additives,

wherein the LLDPE and the HDPE have a MFI190_/2.16 ranging from 0.8 to 1.2 g/lO min.

Copolymers of ethylene with an a-olefm comprising at least four carbon atoms are used as the linear LLDPE according to the invention. In particular, an a-olefm selected from the group consisting of butene- 1, butene-2, isobutene, pentene-l, cis-pentene-2, trans-pentene-2, 2-methylbutene-l, 3-methylbutene-l, 2-methylbutene-2, hexene-l, cis- hexene-2, trans-hexene-2, cis-hexene-3, trans-hexene-2, cis-hexene-3, trans-hexene-3, 2-methylpentene-l, 3-methylpentene-l, 4-methylpentene-l, 2-methylpentene-2, cis-3- mthylpentene-2, trans-3-methyl-pentene-2, cis-4-methylpentene-2, trans-4- methylpentene-2, 2-ethylbutyl-l, 2,3-dimethylbutene-l, 3,3-dimeyhylbutene-l, 2,3- dimethylbutene-2, heptene-lO, octene-l and other similar a-olefms may be used . The most preferable is a copolymer of ethylene and octene-l.

The content of the a-olefm copolymer in the LLDPE is from 2.5 to 8 wt.%, preferably from 3 to 6 wt.%, most preferably from 3.5 to 5 wt.%.

Meanwhile, a polyethylene obtained by copolymerization of ethylene with a- olefins on Ziegler-Natta catalysts or on metallocene catalysts according to the known techniques may be used as the LLDPE.

The LLDPE content based on the total weight of the composition is from 59 to 82 wt.%, preferably from 70 to 82 wt.%, most preferably from 75 to 80 wt.%.

The HDPE grafted with a functional monomer is a homopolymer of ethylene to the macromolecule of which a functional monomer is grafted. Exemplary functional monomers are unsaturated carboxylic acids and their derivatives. The unsaturated carboxylic acids according to the invention include acids comprising 2 to 20 carbon atoms, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. Functional derivatives of these acids include, for example, ethers and anhydrides of unsaturated carboxylic acids. An exemplary unsaturated carboxylic acid ester is alkyl(meth)acrylate, wherein the alkyl comprises up to 24 carbon atoms. Examples of the alkylacrylate and alkyl(meth)acrylate are, particularly, methylmethacrylate, ethylacrylate, n-butylacrylate, isobutylacrylate, 2-ethylhexylacrylate. Examples of anhydrides of an unsaturated carboxylic acid are, particularly, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride. The most preferable functional monomer of the present invention is maleic anhydride.

The amount of the functional monomer grafted to HDPE is at from 0.5 to 2 wt.%, preferably from 1.0 to 1.5 wt.%, relative to the total weight of the HDPE grafted with a functional monomer.

Polyethylene obtained by anionic coordinate polymerization of ethylene at a low pressure in Ziegler-Natta catalyst systems according to the known techniques is used as the HDPE. A functional monomer is grafted on HDPE in conformity with the techniques that are well-known to those skilled in the art, by a periodic or continuous method, using a device for mixing the melt. According to the invention, the graft is effected by reactive extrusion in the presence or in the absence of a radical initiator. A functional monomer is preferably grafted in the presence of a radical initiator, such as an organic peroxide. Examples of the organic peroxide include, but are not limited to, the following products: tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-tert-butyl hydroperoxide, dicumene peroxide, l,3-l,4-bis-(tert-butylperoxyisopropyl)benzene, acetyl peroxide, benzoyl peroxide, isobutyryl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, methylethylketone peroxide, and other organic peroxides. Peroxides may be used in their pure form and may be coated onto a mineral or polymeric filler (peroxide concentrate). Examples of suitable peroxides are commercially available products marketed under such trademarks as Trigonox 301, Luperox DCP, Luperox DC40, Luperox DC40KE, Luperox DC40MG, Luperox DC40P-SP2, Luperox DI, Luperox DTA, Luperox F, Luperox F40, Luperox F40MG, Luperox MIX, Luperox 101, Luperox 101SIL45, Luperox 130XL45, Luperox 801. The amount of said pure initiator added to the composition is preferably in the range from 0.01 to 0.4 wt.%, most preferably from 0.05 to 0.15 wt.%, relative to the total weight of the composition.

The adhesive composition according to the invention the HDPE grafted with a functional monomer in the amount by from 15 to 20 wt.%, preferably from 15 to 18 wt.%, most preferably from 15 to 17 wt.%, relative to the total weight of the composition. The content of the HDPE grafted with a functional monomer of less than 15 wt.% reduces the concentration of functional polar moieties in the interface zone in the vicinity of the protected material that contacts the adhesive composition and, as a consequence, results in a decrease of peel strength. If the content of the HDPE grafted with a functional monomer exceeds 20 wt.%, its compatibility with the LLDPE deteriorates considerably due to heterogeneity of their structures thereby causing adverse changes in morphology of said blend. If the content of the HDPE grafted with a functional monomer is greater than 20 wt.%, the coarsely dispersed and heterogeneous HDPE phase formed in the LLDPE matrix worsensthe structure and properties of the adhesive layer with a polar support (protected material), which deteriorates peel strength accordingly.

Use of polyethylenes that remarkably differ in their density permits enhancing peel strength of the composition. According to the present invention, an LLDPE having a density in the range from 0.915 to 0.925 g/cm³, preferably from 0.916 to 0.920 g/cm³, and an HDPE grafted with a functional monomer, having a density of at least 0.955 g/cm³, preferably at least 0.960 g/cm³, are used as polyethylenes in the adhesive composition. Otherwise, convergence of density values for the polyethylenes (less than 0.955 g/cm³ for the HDPE and more than 0.925 g/cm³ for the LLDPE) will hinder diffusion of the HDPE grafted with a functional monomer to a surface of a material with which the adhesive composition contacts, thereby deteriorating its peel strength.

An MFI is essential for achievement of the technical result of the present invention, too. It has been found that the MFI 190_/2_.1₆ of the HDPE grafted with a functional monomer, as well as the MFL90_/2.16 of the LLDPE, must vary in the range from 0.8 to 1.2 g/lO min, preferably from 0.9 to 1.1 g/lO min.

Meanwhile, it is preferable that the MFI ratios of the LLDPE and the HDPE grafted with a functional monomer are close to or equal to 1. While not wishing to be bound by any particular theory, the authors of the present invention believe that the important role of the MFI values is associated, among others, with optimal molecular weight values of polyethylenes, which, under the conditions of mixing structurally different LLDPE and HDPE, ensures the highest peel strength of the obtained composition. A decrease in melt viscosity (an increase of the MFI) and molecular weight of polyethylenes below the required values results in inevitable deterioration of adhesive characteristics of the composition. As the MFI decreases and the molecular weight grows above the required thresholds, adhesive characteristics of the composition become worse, too, which may be due to the growth of diffusion limitations and a drop in dispersibility of the phase of the HDPE grafted with a functional monomer within the LLDPE matrix.

Therefore, molecular weights of the LLDPE and the HDPE grafted with a functional monomer that are optimal for carrying out the present invention are in the range from 65,000 to 80,000 g/mol, preferably from 70,000 to 75,000 g/mol. The molecular weight distribution for the HDPE grafted with a functional monomer is at least 5.9, preferably at least 6.2.

The authors of the present invention have also discovered that one of the factors influencing the peel strength of the composition, in addition to density and MFI values, is LLDPE branching, i.e. the presence of side branches on the hydrocarbon backbone. As the hydrocarbon chain of an a-olefm, which latter is used as a comonomer in the LLDPE, gets longer, the peel strength of the composition increases monotonically. The highest peel strength is exhibited by compositions in which a copolymer of ethylene with an a-olefm, preferably octene-l, is used as the LLDPE. Octene-l is characterised by the presence of long-chain branches of hydrocarbon chains, i.e. side branches comprising 100 or more carbon atoms, and is preferably produced by reversible chain transfer.

Apart from the LLDPE and the HDPE grafted with a functional monomer, the composition also comprises an elastomer in an amount from 3 to 20 wt.%, preferably from 5 to 15 wt.%, most preferably from 5 to 10 wt.%, relative to the total weight of the composition. This amount of an elastomer is conventionally accepted for such compositions and is disclosed, for example, in prior art references US 8247053, WO0118141. At that, the elastomer is used at a ratio to the HDPE grafted with a functional monomer of from 1 : 1 to 1 :5, preferably from 1 :2 to 1 :3. In the authors’ opinion, the elastomer used within the claimed composition improves compatibility of the LLDPE and the HDPE grafted with a functional monomer and enhances plasticity of the adhesive layer thereby enhancing its strength under external influence.

Copolymers of ethylene with a-olefms comprising 4 to 8 carbon atoms (for example, Engage, Exact and the like) and/or copolymers of ethylene with unsaturated carboxylic acid esters (for example, those manufactured by Du Pont, Exxon Mobil, Dow Chem. under Elvaloy, Lotryl trademarks, and the like) are used as the elastomers according to the invention.

Copolymers of ethylene with unsaturated carboxylic acid esters, which are employed as the elastomers, are random copolymers comprising from 5 to 40 wt.% of an ester comonomer. Exemplary unsaturated carboxylic acid esters are alkylacrylate and/or alkylmethacrylate, wherein the alkyl contains up to 24 carbon atoms. Examples of the alkylacrylate and alkyl(meth)acrylate are, particularly, methylmethacrylate, ethylacrylate, n-butylacrylate, isobutylacrylate, 2-ethylhexylacrylate.

The claimed composition may optionally comprise various additives, for example, antioxidants, UV-absorbers, antistatic agents, crystallization agents, fillers, lubricants, flame retardants, and other additives in an amount from 0 to 1 wt.%, preferably from 0.1 to 0.5 wt.%.

Examples of suitable antioxidants include 2,6-di-tert-butyl-p-cresol, tetrakis- [methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, p-naphthylamine, and paraphenylenediamine.

Examples of UV-absorbers include 2,4-dihydroxybenzophenone, 2-(2’ -hydroxy- 3’5’ -di-t-butylphenyl)-5 -chlorobenzotriazole, 2-(2-hydroxy-3 -t-butyl-5 -methylphenyl)- 5-chlorobenzotriazole, and bis-(2,2’,6,6’-tetramethyl-4-piperidine)sebate.

Examples of antistatic agents include lauryl diethanolamine, palmityl diethanolamine, stearyl diethanolamine, oleyl diethanolamine, behenyl diethanolamine, polyoxyethylene-alkylamines, stearyl-monoglycerides, and 2-hydroxy-4-n- octoxybenzophenone.

Examples of crystallization agents include aluminum p-tert-butylbenzoate, aluminum dibenzylidene-sorbitol, and aluminum hydroxy-di-p-t-butylbenzoate. Fillers that are included in the composition are, in particular, glass fiber, carbon fiber, talc, clay, silica, calcium carbonate, barium sulfate, magnesium hydroxide, calcium hydroxide, and calcium oxide.

Lubricants are utilized to facilitate the manufacture of the composition, in particular, its extrusion. Examples of lubricants include stearamides, oleamides, erucamides, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, polyethylene wax, petrolatum oil.

Examples of flame retardants are metal hydroxides, halogenating agents, antimony oxide, decabromodiphenyl ether, and bis-(3,5-dibromo-4- bromopropyloxyphenyl)sulfone.

The adhesive composition according to the present invention is obtained by blending all components, using the known thermoplastic blending techniques, for example, extrusion, or blending in mixers of various designs. Internal mixers with blades or rotors, external mixers, single-screw extruders, counter-rotating or co-rotating twin-screw extruders may be used.

In accordance with the present invention, the claimed adhesive composition is manufactured in a two-step process by blending and processing the components into a homogeneous melt by means of prior art equipment, for example, mixing equipment (mixers with blades, rolling mills, Banbury mixers, Brabender mixers), single-screw extruders, twin-screw extruders, and similar mixers. Blending is preferably performed in mixing equipment, while the further processing into a homogeneous melt is carried out in an extruder, for example, as described below.

Step 1. Production of an HDPE grafted with a functional monomer

An HDPE and a functional monomer selected from the compounds described above are blended. The functional monomer is grafted either in the presence or in the absence of a radical initiator. The functional monomer is preferably grafted in the presence of a radical initiator, such as an organic peroxide.

The other optional additives may be used before or after the functional monomer has been grafted.

Said components are loaded into mixing equipment and blended for a period of time from 1 to 20 minutes, preferably from 2 to 10 minutes at a temperature from 10 to l00°C, preferably from 20 to 50°C. The so-obtained blend is then processed into a homogeneous melt, preferably in an extruder, at a temperature from 190 to 240°C, preferably from 220 to 230°C. The speed of rotation of the screw is about 250 min ¹.

Step 2. Production of an adhesive composition

The HDPE grafted with a functional monomer obtained in step 1 , an LLDPE and an elastomer are loaded into mixing equipment and blended for a period of time from 1 to 20 minutes, preferably from 2 to 10 minutes, at a temperature from 10 to l00°C, preferably from 20 to 50°C. The so-obtained blend is then processed into a homogeneous melt, preferably in an extruder, at a temperature from 190 to 240°C, preferably from 220 to 230°C. The speed of rotation of the screw is about 250 min ¹. The resultant adhesive composition is granulated and used according to its intended purpose.

The adhesive composition manufactured according to the present invention may be used as a co-extruded adhesive layer in multilayer coatings, preferably in insulation, in particular, for protection of tubes intended for construction of main gas- and oil pipelines.

The present invention also relates to an article that includes an adhesive layer comprising the adhesive composition described above. Such articles include, for example, tubes, cables, films, articles manufactured by extrusion coating the adhesive composition. In particular, the present invention relates to a multilayer tube comprising a multilayer coating with two, three, four, five or more layers, the coating including a polyolefin layer and an adhesive layer adjacent to the polyolefin layer and containing the adhesive composition described above.

The invention will be explained by examples below that are given for illustrative purposes and are not intended to limit the scope of the present disclosure.

Examples

The polyethylenes listed in Table 1 were used as the LLDPE.

N)

Elvaloy AC3427, a copolymer of ethylene and butylacrylate, is used as the elastomer.

Petrolatum oil is used as an optional additive.

Example 1 (comparative)

Step 1. A product manufactured by Du Pont under the Fusabond 100 trademark, having MFI190/2.16 = 2 and a grafted maleic anhydride content of 1 wt.% is used as the maleic anhydride grafted HDPE (see Table 2).

Step 2. A blend comprising 15 wt.% of a maleic anhydride grafted HDPE (Fusabond 100, see its properties in Table 2), 80 wt.% of an LLDPE (PE 5118Q) (see its properties in Table 1), 5 wt.% of a copolymer of ethylene and butylacrylate (for example, Elvaloy AC3427) is provided in a mixer with blades and mixed for 2-10 minutes at a temperature from 10 to 50°C. The resultant blend of components is processed in a LTE-20-44 twin-screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min ¹.

The so-obtained composition is characterised by peel strength to steel of 32.9 N/mm at 23°C.

Example 2 (comparative)

The composition according to Example 1 is provided, save that Sabic 318B (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 30.9 N/mm at 23°C.

Example 3 (comparative)

The composition according to Example 1 is provided, save that Sabic 118 J (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 36.9 N/mm at 23°C.

Example 4 (comparative)

The composition according to Example 1 is provided, save that Daelim XP 9400 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 29.0 N/mm at 23°C.

Example 5 (comparative) The composition according to Example 1 is provided, save that Daelim XP 9200 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 36.7 N/mm at 23°C.

Example 6 (comparative)

The composition according to Example 1 is provided, save that DOW ELITE 5400GS (see its properties in Table 1) is used as the LLDPE.

Example 7 (comparative)

The composition according to Example 1 is provided, save that Bondyram 5108 (see its properties in Table 2) is used as the maleic anhydride grafted HDPE and Daelim XP 9400 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 23.6 N/mm at 23°C.

Example 8 (comparative)

The composition according to Example 7 is provided, save that Daelim XP 9200 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 28.6 N/mm at 23°C.

Example 9 (comparative)

The composition according to Example 1 is provided, save that BIG Scona (see its properties in Table 2) is used as the maleic anhydride grafted HDPE and Sabic 118NJ (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 21.0 N/mm at 23°C.

Example 10 (comparative)

Step 1. Synthesis of MA-PEVP-l (see its properties in Table 2).

A blend consisting of the following components is provided in a mixer with blades: up to 100 wt.% of an HDPE of the PE2NT22-12 grade (Kazannefteorgsintez OAO), 1.0 wt.% of maleic anhydride, 0.125 wt.% of a Trigonox 301 organic peroxide, 0.1 wt.% of petrolactum oil. The resulting blend is mixed for 2 to 10 minutes at a temperature from 10 to 50°C. The finished blend is then processed in a LTE-20-44 twin- screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min ¹. The produced strands are cooled in a water bath and granulated on equipment supplied with the extruder.

Step 2. A blend comprising 15 wt.% of the maleic anhydride functionalized

HDPE produced in step 1, 80.0 wt.% of an LLDPE (PE 5118Q) and 5 wt.% of a copolymer of ethylene and butylacrylate (Elvaloy AC3427) is provided in a mixer with blades and mixed for 2-10 minutes at a temperature from 10 to 50°C. The resultant blend of components is processed in a LTE-20-44 twin-screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min 1

The so-obtained composition is characterised by peel strength to steel of 31.3 N/mm at 23°C.

Example 11 (comparative)

The composition according to Example 10 is provided, save that Sabic 318B (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 35.1 N/mm at 23°C.

Example 12 (comparative)

The composition according to Example 10 is provided, save that Sabic 118 J (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 41.9 N/mm at 23°C.

Example 13 (according to the invention)

The composition according to Example 10 is provided, save that DOWLEX 5056 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 44.1 N/mm at 23°C.

Example 14 (comparative)

The composition according to Example 10 is provided, save that Daelim XP9400 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 29.9 N/mm at 23°C.

Example 15 (according to the invention)

The composition according to Example 10 is provided, save that Daelim XP 9200 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 42.9

N/mm at 23°C.

Example 16 (according to the invention)

The composition according to Example 10 is provided, save that DOW ELITE 5400GS (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 58.7

N/mm at 23°C.

Example 17 (comparative)

Step 1. Synthesis of MA-PEVP-2 (see its properties in Table 2).

A blend consisting of the following components is provided in a mixer with blades: up to 100 wt.% of an HDPE of the PE2NT22-12 grade (Kazannefteorgsintez OAO), 1.0 wt.% of maleic anhydride, 0.20 wt.% of an organic peroxide (Trigonox 301), 0.1 wt.% of petrolactum oil. The resulting blend is mixed for 2 to 10 minutes at a temperature from 10 to 50°C. The finished blend is then processed in a LTE-20-44 twin- screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min ¹. The produced strands are cooled in a water bath and granulated on equipment supplied with the extruder.

Step 2. A blend comprising 15 wt.% of the maleic anhydride functionalized

HDPE produced in step 1, 80.0 wt.% of an LLDPE (Daelim XP 9400) and 5 wt.% of a copolymer of ethylene and butylacrylate (Elvaloy AC3427) is provided in a mixer with blades and mixed for 2-10 minutes at a temperature from 10 to 50°C. The resultant blend of components is processed in a LTE-20-44 twin-screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min 1

The so-obtained composition is characterised by peel strength to steel of 29.3 N/mm at 23°C.

Example 18 (comparative)

The composition according to Example 17 is provided, save that Daelim XP9200 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 31.6 N/mm at 23°C.

Example 19 (comparative)

Step 1. Synthesis of MA-PEVP-3 (see its properties in Table 2).

A blend consisting of the following components is provided in a mixer with blades: up to 100 wt.% of an HDPE of the PE2NT22-12 grade (Kazannefteorgsintez OAO), 1.0 wt.% of maleic anhydride, 0.05 wt.% of an organic peroxide (Trigonox 301), 0.1 wt.% of petrolactum oil. The resulting blend is mixed for 2 to 10 minutes at a temperature from 10 to 50°C. The finished blend is then processed in a LTE-20-44 twin- screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min ¹. The produced strands are cooled in a water bath and granulated on equipment supplied with the extruder.

Step 2. A blend comprising 15 wt.% of the maleic anhydride functionalized

HDPE produced in step 1, 80.0 wt.% of an LLDPE (Sabic 318B) and 5 wt.% of a copolymer of ethylene and butyl acrylate (Elvaloy AC3427) is provided in a mixer with blades and mixed for 2-10 minutes at a temperature from 10 to 50°C. The resultant blend of components is processed in a LTE-20-44 twin-screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min 1

The so-obtained composition is characterised by peel strength to steel of 32.4 N/mm at 23°C.

Example 20 (comparative)

The composition according to Example 19 is provided, save that DOWLEX 5056 (see its properties in Table 1) is used as the LLDPE.

Example 21 (comparative)

The composition according to Example 19 is provided, save that Daelim XP 9400 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 24.3 N/mm at 23°C. Example 22 (comparative)

The composition according to Example 19 is provided, save that Daelim XP 9200 (see its properties in Table 1) is used as the LLDPE.

The so-obtained composition is characterised by peel strength to steel of 36.8 N/mm at 23°C.

Example 23 (comparative)

Step 1. Synthesis of MA-PEVP-4 (see its properties in Table 2).

A blend consisting of the following components is provided in a mixer with blades: up to 100 wt.% of an HDPE of the PE2NT22-12 grade (Kazannefiteorgsintez OAO), 1.0 wt.% of maleic anhydride, 0.02 wt.% of an organic peroxide (Trigonox 301), 0.1 wt.% of petrolactum oil. The resulting blend is mixed for 2 to 10 minutes at a temperature from 10 to 50°C. The finished blend is then processed in a LTE-20-44 twin- screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min ¹. The produced strands are cooled in a water bath and granulated on equipment supplied with the extruder.

Step 2. A blend comprising 15 wt.% of the maleic anhydride functionalized

HDPE produced in step 1, 80.0 wt.% of an LLDPE (DOWLEX 5056) and 5 wt.% of a copolymer of ethylene and butylacrylate (Elvaloy AC3427) is provided in a mixer with blades and mixed for 2-10 minutes at a temperature from 10 to 50°C. The resultant blend of components is processed in a LTE-20-44 twin-screw extruder at a maximum temperature in roller zones of 240°C and at a speed of rotation of the screw of 250 min 1

The so-obtained composition is characterised by peel strength to steel of 27.2 N/mm at 23°C.

Example 24 (comparative)

The composition according to Example 10 is provided, save that a linear medium-density polyethylene (Lumicene mPE) (see its properties in Table 1) is used instead of the LLDPE (PE 5118Q).

The so-obtained composition is characterised by peel strength to steel of 31.5 N/mm at 23°C.

Example 25 (comparative)

The composition according to Example 10 is provided, save that a linear medium-density polyethylene (DOWLEX 5066) (see its properties in Table 1) is used instead of the LLDPE (PE 5118Q).

The so-obtained composition is characterised by peel strength to steel of 30.1 N/mm at 23°C.

Example 26 (according to the invention)

The composition according to Example 10 is provided, save that 17 wt.% instead of 15 wt.% of MA-PEVP-l and 78 wt.% instead of 80 wt.% of the LLDPE (DOW ELITE 5400GS) is used in the second step of manufacturing the adhesive composition.

The so-obtained composition is characterised by peel strength to steel of 62.2 N/mm at 23°C.

Example 27 (according to the invention)

The composition according to Example 16 is provided, save that 20 wt.% instead of 15 wt.% of MA-PEVP-l and 75 wt.% instead of 80 wt.% of the LLDPE (DOW ELITE 5400GS) is used in the second step of manufacturing the adhesive composition.

The so-obtained composition is characterised by peel strength to steel of 52.0 N/mm at 23°C.

Example 28 (comparative)

The composition according to Example 16 is provided, save that 13 wt.% instead of 15 wt.% of MA-PEVP-l and 82 wt.% instead of 80 wt.% of the LLDPE (DOW ELITE 5400GS) is used in the second step of manufacturing the adhesive composition.

The so-obtained composition is characterised by peel strength to steel of 39.5 N/mm at 23°C.

Example 29 (comparative)

The composition according to Example 16 is provided, save that 23 wt.% instead of 15 wt.% of MA-PEVP-l and 72 wt.% instead of 80 wt.% of the LLDPE (DOW ELITE 5400GS) is used in the second step of manufacturing the adhesive composition.

The so-obtained composition is characterised by peel strength to steel of 35.8 N/mm at 23°C.

Example 30 (comparative)

The composition according to Example 16 is provided, save that the Elvaloy AC 3427 elastomer is not used and 85 wt.% instead of 80 wt.% of the LLDPE (DOW ELITE 5400GS) is used in the second step of manufacturing the adhesive composition. The so-obtained composition is characterised by peel strength to steel of 32.4 N/mm at 23°C.

Table 3 show formulations of PE compositions (Examples 1-30) and results of their peel strength determination.

N>

U>



k>

Therefore, as demonstrated by the experimental data above, the claimed adhesive polyethylene composition has increased values of the peel strength to steel and other polar supports (protected materials) in comparison with the prototype and analogues. The values of the peel strength to steel achieved according to the invention are the following: peel strength to steel from 40 to 65 N/mm at 23°C, from 30 to 45 N/mm at 60°C, and from 10 to 25 N/mm at 80°C.

The advantages of the proposed composition are illustrated by the examples given in Table 3.

The examples of the present invention (Examples 12, 13, 15, 16, 26, and 27) demonstrate that the technical result is achievable provided that the following conditions are satisfied:

1) densities of the used polyethylenes must differ considerably from each other; the LLDPE density must be in the range from 0.915 to 0.925 g/cm³, preferably from 0.916 to 0.920 g/cm³, whereas the density of the HDPE grafted with a functional monomer must be at least 0.955 g/cm³, preferably at least 0.960 g/cm³;

2) the MFIi9o_/2_.i6 of the polyethylenes must be in the range from 0.8 to 1.2 g/lO min, preferably from 0.9 to 1.1 g/lO min;

3) the LLDPE must be characterised by a branched structure, i.e. the presence of side chains on the hydrocarbon backbone. An increase in the length of the hydrocarbon chain of an a-olefm used in the LLDPE enhances peel strength, wherein the best technical result is achieved from using an LLDPE that is a copolymer of ethylene with octene-l comprising long-chain branches (Cioo and more).

Claims

1. An adhesive composition comprising, relative to its total weight:

B) from 15 to 20 wt.% of a high-density polyethylene (HDPE) grafted with a functional monomer, having a density of at least 0.955 g/cm³,

C) from 3 to 20 wt.% of an elastomer,

D) up to 100% of optional additives,

wherein the LLDPE and the HDPE have a MFI190/2.16 in the range from 0.8 to 1.2 g/lO min.

2. The adhesive composition according to claim 1, wherein the content of the LLDPE, relative to the total weight of the composition, is from 70 to 82 wt.%.

3. The adhesive composition according to claim 2, wherein the content of the LLDPE, relative to the total weight of the composition, is from 75 to 80 wt.%.

4. The adhesive composition according to claim 1, wherein the content of the HDPE grafted with a functional monomer, relative to the total weight of the composition, is from 15 to 18 wt.%.

5. The adhesive composition according to claim 4, wherein the content of the HDPE grafted with a functional monomer, relative to the total weight of the composition, is from 15 to 17 wt.%.

6. The adhesive composition according to claim 1, wherein the content of the elastomer, relative to the total weight of the composition, is from 5 to 15 wt.%.

7. The adhesive composition according to claim 6, wherein the content of the elastomer, relative to the total weight of the composition, is from 5 to 10 wt.%.

8. The adhesive composition according to claim 1, wherein the elastomer is used at a weight ratio to the HDPE grafted with a functional monomer of 1 : 1 to 1 :5.

9. The adhesive composition according to claim 8, wherein the elastomer is used at a weight ratio to the HDPE grafted with a functional monomer of 1 :2 to 1 :3.

10. The adhesive composition according to claim 1, wherein the density of the LLDPE is from 0.916 to 0.920 g/cm³.

11. The adhesive composition according to claim 10, wherein the density of the HDPE grafted with a functional monomer is at least 0.960 g/cm³.

12. The adhesive composition according to claim 1, wherein the MFI 190_/2_.1₆ for the LLDPE and the E1DPE is in the range from 0.9 to 1.1 g/lO min.

13. The adhesive composition according to claim 1, wherein the MFI ratio for the LLDPE and the HDPE is close to or equal to 1.

14. The adhesive composition according to claim 1, wherein molecular weights of the LLDPE and the HDPE grafted with a functional monomer are in the range from 65,000 to 80,000 g/mol.

15. The adhesive composition according to claim 14, wherein molecular weights of the LLDPE and the HDPE grafted with a functional monomer are in the range from 70,000 to 75,000 g/mol.

16. The adhesive composition according to claim 1, wherein the molecular weight distribution for the HDPE grafted with a functional monomer is at least 5.9.

17. The adhesive composition according to claim 16, wherein the molecular weight distribution for the HDPE grafted with a functional monomer is at least 6.2.

18. The adhesive composition according to claim 1, wherein the LLDPE is a copolymer of ethylene with an a-olefm comprising at least four carbon atoms.

19. The adhesive composition according to claim 18, wherein the content of the a- olefin copolymer in the LLDPE is from 2.5 to 8 wt.%.

20. The adhesive composition according to claim 19, wherein the content of the a- olefin copolymer in the LLDPE is from 3 to 6 wt.%.

21. The adhesive composition according to claim 20, wherein the content of the a- olefin copolymer in the LLDPE is from 3.5 to 5 wt.%.

22. The adhesive composition according to claim 1, wherein the LLDPE is a polyethylene characterised by the presence of long-chain branches of hydrocarbon chains, i.e. side branches comprising 100 or more carbon atoms.

23. The adhesive composition according to claim 21, wherein the LLDPE is a polyethylene characterised by the presence of long-chain branches of hydrocarbon chains, i.e. side branches comprising 100 or more carbon atoms, obtainable by reversible chain transfer.

24. The adhesive composition according to claim 1, wherein the HDPE grafted with a functional monomer is a homopolymer of ethylene to the macromolecule of which the functional monomer is grafted.

25. The adhesive composition according to claim 24, wherein the functional monomer is unsaturated carboxylic acids and derivatives thereof.

26. The adhesive composition according to claim 25, wherein the unsaturated carboxylic acids are acids containing from 2 to 20 carbon atoms.

27. The adhesive composition according to claim 25, wherein derivatives of the unsaturated carboxylic acids include ether derivatives and anhydrides of unsaturated carboxylic acids.

28. The adhesive composition according to claim 27, wherein the ether derivatives of the unsaturated carboxylic acids include, in particular, alkyl(meth)acrylate, wherein the alkyl comprises up to 24 carbon atoms.

28. The adhesive composition according to claim 27, wherein the anhydrides of the unsaturated carboxylic acids include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride.

29. The adhesive composition according to claim 1, wherein the functional monomer is maleic anhydride.

30. The adhesive composition according to claim 1, wherein the amount of the functional monomer grafted on the HDPE is from 0.5 to 2 wt.%, relative to the total weight of the HDPE grafted with a functional monomer.

31. The adhesive composition according to claim 30, wherein the amount of the functional monomer grafted on the HDPE is from 1.0 to 1.5 wt.%, relative to the total weight of the HDPE grafted with a functional monomer.

32. The adhesive composition according to claim 1, wherein the HDPE grafted with a functional monomer is produced by reactive extrusion of the HDPE and the functional monomer in the presence or in the absence of a radical initiator.

33. The adhesive composition according to claim 32, wherein the radical initiator is an organic peroxide.

34. The adhesive composition according to claim 33, wherein the amount of the organic peroxide is from 0.01 to 0.4 wt.%, most preferably from 0.05. to 0.15 wt.%, relative to the total weight of the composition.

35. The adhesive composition according to claim 1, wherein the elastomer is a copolymer of ethylene with a-olefms comprising 4 to 8 carbon atoms and/or a copolymer of ethylene with esters of unsaturated carboxylic acids.

36. The adhesive composition according to claim 35, wherein copolymers of ethylene with esters of unsaturated carboxylic acids are random copolymers comprising from 5 to 40 wt.% of an ester comonomer.

37. The adhesive composition according to claim 36, wherein said ester of unsaturated carboxylic acids is selected from alkylacrylate and/or alkyl(meth)acrylate, wherein the alkyl comprises up to 24 carbon atoms.

38. The adhesive composition according to claim 1, wherein the other additives comprise antioxidants, UV-absorbers, antistatic agents, crystallization agents, fillers, lubricants, flame retardants.

39. The adhesive composition according to claim 1, wherein the other additives are used in an amount from 0 to 1 wt.%, preferably from 0.1 to 0.5 wt.%.

40. A process for manufacturing an adhesive composition, comprising the steps of:

providing an HDPE grafted with a functional monomer by blending an HDPE and a functional monomer, and

blending and processing the mixture of the HDPE grafted with a functional monomer obtained in the preceding step, an LLDPE and an elastomer into a homogeneous melt,

wherein said steps are carried out in regard to the following components, taken in the following amount, relative to the total weight of the composition:

C) from 3 to 20 wt.% of an elastomer,

D) up to 100% of optional additives,

41. The process for manufacturing a composition according to claim 40, wherein the content of the LLDPE, relative to the total weight of the composition, is from 70 to 82 wt.%.

42. The process for manufacturing a composition according to claim 41, wherein the content of the LLDPE, relative to the total weight of the composition, is from 75 to 80 wt.%.

43. The process for manufacturing a composition according to claim 40, wherein the content of the HDPE grafted with a functional monomer, relative to the total weight of the composition, is from 15 to 18 wt.%.

44. The process for manufacturing a composition according to claim 43, wherein the content of the HDPE grafted with a functional monomer, relative to the total weight of the composition, is from 15 to 17 wt.%.

45. The process for manufacturing a composition according to claim 40, wherein the content of the elastomer, relative to the total weight of the composition, is from 5 to 15 wt.%.

46. The process for manufacturing a composition according to claim 45, wherein the content of the elastomer, relative to the total weight of the composition, is from 5 to 10 wt.%.

47. The process for manufacturing a composition according to claim 40, wherein the elastomer is used at a weight ratio to the HDPE grafted with a functional monomer of 1 :1 to 1 :5.

48. The process for manufacturing a composition according to claim 47, wherein the elastomer is used at a weight ratio to the HDPE grafted with a functional monomer of 1 :2 to 1 :3.

49. The process for manufacturing a composition according to claim 40, wherein the density of the LLDPE is from 0.916 to 0.920 g/cm³.

50. The process for manufacturing a composition according to claim 40, wherein the density of the HDPE grafted with a functional monomer is at least 0.960 g/cm³.

51. The process for manufacturing a composition according to claim 40, wherein the MFIi9o_/2_.i6 for the LLDPE and the HDPE is in the range from 0.9 to 1.1 g/lO min.

52. The process for manufacturing a composition according to claim 40, wherein the MFI ratio for the LLDPE and the HDPE is close to or equal to 1.

53. The process for manufacturing a composition according to claim 40, wherein molecular weights of the LLDPE and the HDPE grafted with a functional monomer are in the range from 65,000 to 80,000 g/mol.

54. The process for manufacturing a composition according to claim 40, wherein molecular weights of the LLDPE and the HDPE grafted with a functional monomer are in the range from 70,000 to 75,000 g/mol.

55. The process for manufacturing a composition according to claim 40, wherein the molecular weight distribution for the HDPE grafted with a functional monomer is at least 5.9.

56. The process for manufacturing a composition according to claim 40, wherein the molecular weight distribution for the HDPE grafted with a functional monomer is at least 6.2.

57. The process for manufacturing a composition according to claim 40, wherein said LLDPE is a polyethylene characterised by the presence of long-chain branches of hydrocarbon chains, i.e. side branches comprising 100 or more carbon atoms.

58. The process for manufacturing a composition according to claim 40, wherein said LLDPE is a polyethylene characterised by the presence of long-chain branches of hydrocarbon chains, i.e. side branches comprising 100 or more carbon atoms, obtainable by reversible chain transfer.

59. The process for manufacturing a composition according to claim 40, wherein the functional monomer is maleic anhydride.

60. The process for manufacturing a composition according to claim 40, wherein the amount of the functional monomer grafted on the HDPE is from 0.5 to 2 wt.%, relative to the total weight of the HDPE grafted with a functional monomer.

61. The process for manufacturing a composition according to claim 40, wherein the amount of the functional monomer grafted on the HDPE is from 1.0 to 1.5 wt.%, relative to the total weight of the HDPE grafted with a functional monomer.

62. The process for manufacturing a composition according to claim 40, wherein the other additives comprise antioxidants, UV-absorbers, antistatic agents, crystallization agents, fillers, lubricants, flame retardants.

63. The process for manufacturing a composition according to claim 40, wherein the other additives are used in an amount from 0 to 1 wt.%, preferably from 0.1 to 0.5 wt.%.

64. The process for manufacturing a composition according to claim 40, comprising the step of blending the HDPE and the functional monomer in the presence or in the absence of a radical initiator.

65. The process for manufacturing a composition according to claim 64, wherein the HDPE and the functional monomer are blended for a period of time from 1 to 20 minutes, preferably from 2 to 10 minutes at a temperature from 10 to l00°C, preferably from 20 to 50°C.

66. The process for manufacturing a composition according to claim 40, wherein the other optional additives are added before or after the functional monomer has been grafted.

67. The process for manufacturing a composition according to claim 40, comprising the step of blending the HDPE grafted with a functional monomer with the

LLDPE and the elastomer for a period of time from 1 to 20 minutes, preferably from 2 to 10 minutes at a temperature from 10 to l00°C, preferably from 20 to 50°C.

68. The process for manufacturing a composition according to claim 40, wherein the processing into a homogeneous melt is carried out at a temperature from 190 to 240°C, preferably from 220 to 230°C.

69. The process for manufacturing a composition according to claim 40, wherein the blending and processing into a homogeneous melt is carried out using mixing equipment and an extruder.

70. Use of the adhesive polyethylene composition according to any of claims 1 to 39 as an adhesive layer in multilayer coatings.

71. The use according to claim 70, wherein the coating is, in particular, multilayer insulation of tubes for constructing main gas- and oil pipelines.

72. A tube provided with multilayer insulation comprising an adhesive layer including the adhesive polyethylene composition according to any of claims 1 to 39.