RU2799590C2 - Polyethylene-based adhesion composition, method for its production and application - Google Patents

Abstract

FIELD: polymers.

SUBSTANCE: present invention relates to a polyethylene-based adhesive composition for use as an adhesive layer in multilayer products. Adhesive composition characterized by adhesive 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, containing in relation to the total mass of the composition the following components: A) from 59 to 82% wt. of linear low density polyethylene (LLDPE) having a density in the range of 0.915 to 0.925 g/cm³ and characterized by a branched hydrocarbon chain with side branches containing at least 4 carbon atoms; B) from 15 to 20% wt. of high-density polyethylene (HDPE) grafted with a functional monomer - maleic anhydride, having a density of not less than 0.960 g/cm³, characterized by a molecular weight distribution value of not less than 5.9 and weight average molecular weights in the range from 65,000 to 7,0000 g/mol; C) from 3 to 20% wt. elastomer, which is a copolymer of ethylene with α-olefins and/or copolymers of ethylene with esters of unsaturated carboxylic acids; D) optional additives - up to 100%, while LLDPE and HDPE are characterized by an MFR_190/2.16 in the range from 0.8 to 1.2 g/10 min, and the ratios of MFR of polyethylenes: LLDPE and HDPE grafted with a functional monomer is close to or equal to 1. The composition is obtained by mixing and processing components into a homogeneous hot melt using mixing equipment and an extruder. The resulting adhesive composition has high values of adhesive strength, including at elevated temperatures. The invention also relates to the use of an adhesive composition based on polyethylene as an adhesive layer in multilayer coatings, in particular as a multilayer insulation of pipes intended for the construction of gas and oil pipelines.

EFFECT: improving the adhesive strength of the composition based on polyethylene, in particular, improving the adhesion strength to steel at 23°C to values from 41 to 62 N/mm, at 60°C to values from 20 to 45 N/mm, at 80°C to values from 15 to 25 N/mm, as well as in reducing the concentration of polyethylene used in the composition, grafted with a functional monomer, which is attractive in terms of economic indicators.

56 cl, 3 tbl, 30 ex

Description

Field of technology to which the invention relates

The invention relates to a polyethylene-based adhesive composition intended for use as an adhesive layer for application to various metal surfaces for the purpose of anti-corrosion protection, as well as to a method for producing said composition. In particular, the adhesive compositions of the present invention are used to insulate pipes in the construction of gas and oil pipelines. In addition to pipe insulation, the compositions of the present invention find use as an adhesive layer in other multilayer systems, such as coatings, films, plastics, ceramics.

State of the art

From the prior art document US 6855432, 03.08.1990 [1], compositions based on polyethylene suitable for use as adhesive coatings are known. For example, in [1], such a composition is disclosed, used as an adhesive layer between a metal and a polymer, containing polyethylene or its copolymers with α-olefins. The known composition contains: (A) from 20 to 60 wt. hours of polyethylene; (B) 10 to 30 wt. hours of polyethylene grafted with maleic anhydride; (C) 10 to 35 wt. including high-strength polystyrene; (D) 10 to 25 wt. including elastomer. US 6855432 discloses the use of polymer components grafted with various functional monomers in the composition to achieve higher values of adhesive strength, as well as the production of such polymer components using catalysts of different nature. Achievable range of adhesive strength according to [1] is from 16.4 to 36.3 N/mm.

Patent RU 2265618, 10.01.2002, [2], presents a composition suitable for multilayer coatings of metals, glass, plastics, ceramics. The known composition has a multi-component composition based on polyethylene or its copolymers with α-olefins, and includes: in relation to the total mass of the mixture; C) a copolymer of ethylene with an α-olefin in an amount of from 50 to 90% wt. in relation to the total mass of the mixture; C) ethylenically unsaturated dicarboxylic acids and/or their anhydrides. The known invention is directed to the use of polymer components grafted with various functional monomers in the composition to achieve higher values of adhesive strength, as well as to obtain such polymer components using catalysts of different nature. The technical result of the invention described in [2] is the adhesive strength at 23°C at the level of 27.5 N/mm, and at 80°C - 25 N/mm; the specified technical result is achieved as a result of grafting two components A) and B), which are part of the composition, with maleic anhydride in one stage.

In the patent EA 007577, 29.12.2006, [3], a multicomponent composition based on polyethylene for various applications, in particular, for insulating metal pipes, is also disclosed, having the following composition: A) non-elastomeric polyethylene in an amount of from 40 to 97% wt. from the total weight of the composition and B) an elastomer containing an elastomeric ethylene copolymer with polar comonomer groups, where component A) or components A) and B) are grafted using a functional monomer (modifying agent). The composition described in [3] provides for the use of polymer components grafted with various functional monomers in the composition to achieve higher values of adhesive strength, as well as the production of such polymer components using catalysts of different nature. The technical solution described in [3] ensures the achievement of adhesive strength in wider temperature ranges, for example, at the level of 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 95-100°C. These values of adhesive strength are achieved by obtaining polyethylene grafted with maleic anhydride on a catalyst with a single active site, in particular, when using as a catalyst a metallocene component on a porous carrier.

Adhesive compositions used as coatings perform a protective function, they are subject to a number of requirements, first of all, the strongest adhesion of the composition to the surface of the protected material must be realized. Strong adhesion as a property can be characterized by adhesive strength, that is, peel strength to a specific material, in particular, in the context of the present invention, to steel. It should be noted that these values of adhesive strength are insufficient to implement the functions of protecting metal surfaces from mechanical damage and corrosion in a wide temperature range, in particular from 23°C to 80°C.

As can be seen from the prior art, it is a common modification of polyethylene with maleic anhydride, which is used in almost all modern adhesive compositions. It is used both in the form of a finished maleized product, for example, Polybond 3009 (US 5637410, [4], WO 9509212, [5]), and is prepared immediately before use by grafting maleic anhydride onto polyethylenes of various grades during a two-stage process for obtaining an adhesive composition .

The concentration of polyethylene grafted with maleic anhydride has a significant impact on the properties of the composition. Prior art documents [1] - [5] noted the need to reduce the concentration of polyethylene grafted with maleic anhydride, in terms of the attractiveness of such a composition, both from an economic point of view, and from the point of view of reducing the concentration of toxic maleic anhydride in the composition. For example, in patent RU 2265618 [2] the concentration of polymers grafted with functional monomers, in relation to the sum of the components, is from 0.05 to 0.15% wt. However, in none of the documents [1] - [5] there is no information on the effect of reducing the concentration of polyethylene grafted with maleic anhydride on adhesive strength.

The closest in technical essence to the present invention is patent US 8247053 (28.01.2010 SK GLOBAL CHEMICAL KR), [6], which discloses an adhesive composition based on polyethylene, and is selected as a prototype of the present invention. Described in [6] adhesive composition contains from 1 to 40% wt. polyethylene or its copolymers with α-olefins (component A) grafted with a functional monomer, or a mixture of polyethylene (component A1) with a second polymer (component A2) other than Al, in which components A1 and A2 are jointly modified by grafting an unsaturated polar monomer selected from unsaturated carboxylic acids and their anhydrides. The content of unsaturated polar monomer is from 0 to 10,000 parts per million (ppm). Also described in [6] composition contains from 25 to 98% wt. ungrafted polyethylene (component B) obtained on metallocene catalysts, with a density of 0.910-0.930 g/cm ³ , from 1 to 35% wt. an elastomeric product (component C), which is either a copolymer of ethylene with α-olefins having a density of 0.860-0.900 g/cm ³ or copolymers of ethylene with alkyl methacrylate or terpolymers of ethylene, alkyl methacrylates and maleic anhydride, and a peroxide.

From [6] it is also known that in order to improve the processability of the adhesive composition based on polyethylene, sliding additives are used. As such additives, stearamides, oleamides, erucamides, calcium, zinc and aluminum stearates, as well as polyethylene waxes are mentioned in an amount of from 0.01 to 1% wt.

Obtaining an adhesive composition according to US 8247053 is a two-stage process, including the stage of mixing and modifying one or more polyethylene A, with further dilution of the resulting mixture with polymers B and component C. Mixing is carried out in a twin screw extruder. The composition obtained by a known method is used as an adhesive layer in metal pipes coated with an epoxy layer to protect them from corrosion.

A disadvantage of the composition known from [6] is insufficiently high values of adhesive strength, not more than 37 N/mm. In addition, the process for producing the non-grafted polyethylene component (component B) of the known composition is particularly limited to the use of a metallocene catalyst.

Thus, there is a need to create an adhesive composition based on polyethylene with high values of adhesive strength, including at elevated temperatures.

The objective of the present invention is to create an adhesive composition based on polyethylene with high values of adhesive strength, including at elevated temperatures.

Technical result of the present invention is to improve the adhesive strength of the composition based on polyethylene, in particular the improvement of the adhesion strength to steel at 23°C to values from 41 to 62 N/mm, at 60°C to values from 20 to 45 N/mm, at 80° C to values from 15 to 25 N/mm. An additional technical result consists in reducing the concentration of polyethylene grafted with a functional monomer used in the composition, which is attractive in terms of economic indicators.

To achieve the technical result according to the present invention, 1) the values of the densities used in the composition of polyethylenes, 2) the MFI of polyethylenes, and 3) the branched structure of the hydrocarbon chain of LLDPE are essential. The specified technical result is achieved the use of a binary mixture of polyethylenes in the composition, consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), which differ significantly from each other in their density and are characterized by melt flow index (MFR) values_190/2.16) in the range from 0.8 to 1.2 g/10 min.

The inventors of the present invention have unexpectedly found that the adhesive strength of the composition is significantly improved by using a linear low density polyethylene characterized by a branched hydrocarbon chain with side branches containing at least 4 carbon atoms. In this case, the best technical result is achieved when using LLDPE, which is characterized by the presence of long-chain branches of hydrocarbon chains, that is, side branches containing 100 or more carbon atoms.

Description of the invention

In accordance with the present invention, an adhesive composition is claimed containing, in relation to the total mass of the composition, the following components:

A) from 59 to 82% wt. linear low density polyethylene (LLDPE) having a density in the range of 0.915 to 0.925 g/cm ³ and characterized by a branched hydrocarbon chain with side branches containing at least 4 carbon atoms;

B) from 15 to 20% wt. high density polyethylene (HDPE) grafted with a functional monomer having a density of not less than 0.955 g/cm ³ ;

C) from 3 to 20% wt. elastomer,

D) optional additives - up to 100%,

while LLDPE and HDPE are characterized by an MFI _{of 190/2.16} in the range from 0.8 to 1.2 g/10 min.

Hereinafter, linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) are referred to as LLDPE and HDPE, respectively.

As LLDPE, according to the present invention, copolymers of ethylene with an α-olefin containing at least four carbon atoms are used. In particular, an α-olefin selected from the group consisting of butene-1, butene-2, isobutene, pentene-1, cis-pentene-2, trans-pentene-2, 2-methylbutene-1, 3-methylbutene- 1, 2-methylbutene-2, hexene-1, cis-hexene-2, trans-hexene-2, cis-hexene-3, trans-hexene-3, 2-methylpentene-1, 3-methylpentene-1, 4- methylpentene-1, 2-methylpentene-2, cis-3-methylpentene-2, trans-3-methylpentene-2, cis-4-methylpentene-2, trans-4-methylpentene-2, 2-ethylbutene-1, 2, 3-dimethylbutene-1, 3,3-dimethylbutene-1, 2,3-dimethylbutene-2, heptene-1, octena-1 and the like α-olefins. Most preferred is an ethylene-octene-1 copolymer.

The content of α-olefin comonomer in LLDPE is from 2.5 to 8% wt., preferably from 3 to 6% wt., most preferably from 3.5 to 5% wt.

In this case, polyethylene obtained by copolymerization of ethylene with α-olefins on Ziegler-Natta catalysts, or on metallocene catalysts, according to standard industrial technologies, can be used as LLDPE.

The content of LLDPE in 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.

HDPE grafted with a functional monomer is an ethylene homopolymer with a functional monomer grafted onto its macromolecule. Examples of functional monomers are unsaturated carboxylic acids and their derivatives. Unsaturated carboxylic acids according to the invention include acids containing from 2 to 20 carbon atoms, such as acrylic, methacrylic, maleic, fumaric and itaconic acid. Functional derivatives of these acids include, for example, ester derivatives and anhydrides of unsaturated carboxylic acids. An example of esters of unsaturated carboxylic acids is alkyl(meth)acrylate, where alkyl contains up to 24 carbon atoms. Examples of alkyl acrylate and alkyl methacrylate are, in particular, methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate. Examples of unsaturated carboxylic acid anhydrides are, in particular, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride. The most preferred functional monomer of the present invention is maleic anhydride.

The amount of functional monomer grafted onto the HDPE is 0.5 to 2%, preferably 1.0 to 1.5%, based on the total weight of the HDPE grafted with the functional monomer.

As HDPE in the present invention, polyethylene is used, obtained by the anionic-coordination polymerization of ethylene at low pressure on Ziegler-Natta catalysts using standard industrial technologies. The grafting of the functional monomer to HDPE can be done in a batch or continuous manner using a melt agitator, which are techniques well known to those skilled in the art. In accordance with the present invention, grafting is carried out by reactive extrusion in the presence or absence of a radical initiator. Preferably, the grafting of the functional monomer is carried out in the presence of a radical initiator such as an organic peroxide. Examples of organic peroxide include, but are not limited to, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, 1,3-1,4-bis-(tert-butylperoxyisopropyl)benzene, acetyl peroxide, benzoyl peroxide , isobutyryl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, methyl ethyl ketone peroxide, and other organic peroxides. Peroxides can be used both in pure form and applied to a mineral or polymer filler (peroxide concentrate). Examples of suitable peroxides are commercially available products known under trade names such 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 agent in pure form added to the composition is preferably in the range from 0.01 to 0.4% wt., most preferably from 0.05 to 0.15% based on the total weight of the composition.

The content of HDPE grafted with a functional monomer in the adhesive composition according to the invention is from 15 to 20% by weight, preferably from 15 to 18% by weight, most preferably from 15 to 17% by weight. based on the total weight of the composition. The content of HDPE grafted with a functional monomer is less than 15% wt. leads to a decrease in the concentration of functional polar groups in the interfacial zone near the protected material in contact with the adhesive composition and, as a consequence, to a decrease in adhesive strength. An increase in the content of HDPE grafted with a functional monomer by more than 20% wt. leads to a significant deterioration in its compatibility with LLDPE due to the heterogeneity of their structures, which causes negative changes in the morphology of this mixture. Formed at more than 20% wt. content of HDPE grafted with a functional monomer, the coarse and inhomogeneous HDPE phase in the LLDPE matrix causes a deterioration in the structure and properties of the adhesive layer with a polar substrate (protected material), which leads to a corresponding deterioration in adhesive strength.

The use of polyethylenes, which differ significantly from each other in their density, makes it possible to increase the adhesive strength of the composition. In accordance with the invention, as polyethylenes in the composition, LLDPE is used, which is characterized by a density in the range from 0.915 to 0.925 g/cm ³ , preferably from 0.916 to 0.920 g/cm ³ and HDPE grafted with a functional monomer, which is characterized by a density of at least 0.955 g/cm ³ , preferably not less than 0.960 g/cm ³ . Otherwise, convergence of density values for polyethylenes (less than 0.955 g/cm ³ for HDPE and more than 0.25 g/cm ³ for LLDPE) will make it difficult for the HDPE grafted with a functional monomer to diffuse to the surface of the material with which the adhesive composition is in contact , which will lead to deterioration of its adhesive strength.

The key to achieving the technical result of the present invention is also the value of the MFR. It has been found that the MFR _190/2.16 of functional monomer grafted HDPE, like the MFR _190/2.16 LLDPE, should range from 0.8 to 1.2 g/10 min, preferably from 0.9 to 1 .1 g/10 min.

In this case, it is preferable that the ratio of the MFR of polyethylenes: LLDPE and HDPE grafted with a functional monomer be close to or equal to 1.

Without being bound by any theory, the authors of the present invention believe that the important role of the MFR values is associated, among other things, with the optimal values of the molecular weight of polyethylenes, which, under conditions of mixing LLDPE and HDPE of heterogeneous structure, provides the highest adhesive strength of the resulting composition. Reducing the melt viscosity (increase in MFI) and the molecular weight of polyethylenes below the required values leads to an inevitable deterioration in the adhesive characteristics of the composition. With a decrease in the MFI and an increase in the molecular weight of polyethylenes above the required values, the adhesion characteristics of the composition also deteriorate, which is probably associated with an increase in diffusion restrictions and a decrease in the ability to disperse the HDPE phase grafted with a functional monomer in the LLDPE matrix.

Thus, for the implementation of the present invention, the optimal molecular weights of LLDPE and HDPE grafted with a functional monomer 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 HDPE grafted with a functional monomer is at least 5.9, preferably at least 6.2.

Also, the authors of the present invention have unexpectedly found that one of the factors affecting the adhesive strength of the composition, in addition to the density and MFR values, is the branching of LLDPE, that is, the presence of side branches from the main hydrocarbon chain. With an increase in the length of the hydrocarbon chain used in the composition of LLDPE comonomer - α-olefin, there is a monotonous increase in the adhesive strength of the composition. At the same time, the greatest adhesive strength is demonstrated by compositions where LLDPE is a copolymer of ethylene with an α-olefin, preferably octene-1, which is characterized by the presence of long-chain branches of hydrocarbon chains, that is, side branches containing 100 or more carbon atoms, preferably obtained by the mechanism of reversible chain transmission.

In addition to LLDPE and HDPE grafted with a functional monomer, the composition also includes an elastomer in an amount of 3 to 20% wt., preferably 5 to 15% wt., most preferably 5 to 10% wt. in relation to the total weight of the composition; such an amount of elastomer is conventional for such compositions and is disclosed, for example, in the prior art US8247053, WO0118141. In this case, the elastomer is used in a weight ratio to HDPE grafted with a functional monomer equal to from 1:1 to 1:5, preferably from 1:2 to 1:3. According to the authors, the use of an elastomer in the composition improves the compatibility of LLDPE and HDPE grafted with a functional monomer, and also increases the plasticity of the adhesive layer, which in turn increases its strength under external influence.

As elastomers according to the invention, copolymers of ethylene with α-olefins containing from 4 to 8 carbon atoms (for example, brands Engage, Exact and the like) and/or copolymers of ethylene with esters of unsaturated carboxylic acids (for example, manufactured by Du Pont , Exxon Mobil, Dow Chem. under the brands Elvaloy, Lotryl, and the like).

The copolymers of ethylene with esters of unsaturated carboxylic acids used as elastomers are random copolymers with an ester comonomer content of 5 to 40% by weight. Examples of esters of unsaturated carboxylic acids are alkyl acrylate and/or alkyl methacrylate, where alkyl contains up to 24 carbon atoms. Examples of alkyl acrylate and alkyl methacrylate are, in particular, methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate.

The claimed composition may also optionally include various additives, for example, antioxidants, UV absorbers, antistatic agents, crystallizing agents, fillers, sliding additives, flame retardants and other additives, in an amount of 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) sebacate.

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 crystallizing agents include aluminum p-tert-butyl benzoate, dibenzylidene sorbitol, and aluminum hydroxide-p-t-butyl benzoate.

The fillers included in the composition are, in particular, glass fiber, carbon fiber, talc, clay, silicon oxide, calcium carbonate, barium sulfate, magnesium hydroxide, calcium hydroxide and calcium oxide.

Glidants are used to facilitate the manufacture of the composition, in particular its extrusion. Examples of lubricants include stearamides, oleamides, erucinamides, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, polyethylene wax, liquid paraffin.

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

The adhesive composition of the present invention is obtained by mixing all the components, using known methods of mixing thermoplastic materials, for example, extrusion or mixing in mixers of various designs. Indoor mixers with paddles or rotors, open mixers, single screw extruders, extruders with two co-rotating or counter-rotating screws can be used.

In accordance with the present invention, the claimed adhesive composition is obtained in a two-stage method by mixing and subsequent processing of the components into a homogeneous melt using equipment known from the prior art, for example, mixing equipment (paddle mixers, rollers, Banbury mixers, Brabender mixers), single screw, twin screw extruder and other similar mixers. Preferably mixing is carried out in a mixing equipment and further processing into a homogeneous melt is carried out in an extruder, for example, as described below.

1 stage. Obtaining HDPE grafted with a functional monomer

Mix HDPE and functional monomer, which use the compounds described earlier. Grafting of the functional monomer is carried out in the presence or absence of a radical initiator. Preferably, the grafting of the functional monomer is carried out in the presence of a radical initiator such as an organic peroxide.

Other optional additives may be added before or after functional monomer grafting.

These components are loaded into a mixing equipment and mixed for a period of time from 1 to 20 minutes, preferably from 2 to 10 minutes at a temperature of from 10 to 100°C, preferably from 20 to 50°C. Next, the resulting mixture is processed into a homogeneous melt, preferably in an extruder, at a temperature of from 190 to 240°C., preferably from 220 to 230°C. The number of revolutions of the screw is approximately 250 min ^-1 .

2 stage. Getting the adhesive composition

The functional monomer-grafted HDPE obtained in step 1, the LLDPE and the elastomer are charged into a mixing equipment and mixed for a period of 1 to 20 minutes, preferably 2 to 10 minutes, at a temperature of 10 to 100° C., preferably 20 to 50° WITH. Next, the resulting mixture is processed into a homogeneous melt, preferably in an extruder, at a temperature of from 190 to 240°C., preferably from 220 to 230°C. The number of revolutions of the screw is approximately 250 min ^-1 . The adhesive composition thus obtained is granulated and then used for its intended purpose.

The use of the adhesive composition obtained in accordance with the present invention provides for its use as a co-extruded adhesive layer, in multilayer coatings, preferably in insulation to protect, in particular, pipes intended for the construction of gas and oil pipelines.

The present invention also relates to an article that includes an adhesive layer containing the adhesive composition described above. Such products, for example, include pipes, cables, films, products made with the application of an adhesive composition in an extrusion process. The present invention particularly relates to a multilayer pipe, i.e. a pipe provided with a multilayer coating with two, three, four, five or more layers, which includes a polyolefin layer and an adhesive layer adjacent to the polyolefin layer, which contains the adhesive composition described above.

The invention will be further explained by examples, which are given to illustrate the present invention and are not intended to limit its scope.

Examples of the invention

The polyethylenes shown in Table 1 were used as LLDPE.

Table 1 Characteristics of the polyethylenes used in the examples of the invention.

Brand Manufacturer Catalyst type Density, g/cm ³ PTR _190/
2.16 Melting temperature, °С The degree of crystal personality,% Somono-mer Additives Yield strength
MD/TD, MPa Tensile strength Rel. extension at break
MD/TD, % PE XP 9400 Daelim Metallocene. 0.917 3.7-3.0 114 hexene JSC 44/36 470/650 PE XP 9200 Daelim Metallocene. 0.917 1.0 116 44.3 hexene AO, RRA 57/45 580/620 Sabic 318B Sabic C-Natta 0.918 2.8 122 41.6 butene 13/10 30/18.5 470/610 LLDPE 118NJ Sabic C-Natta 0.918 1.0 122 butene JSC 11/11.5 40/32 750/800 Lumicene mPE M3410EP Total Metallocene 0.934 0.9 124 hexene AO, RRA 47/43 630/700 DOWLEX 5056 Dow C-Natta 0.919 1.1 123, 109 39.7 octene JSC 7.5/8 38/37 810/920 DOWLEX 5066 Dow C-Natta 0.934 1.7 125 52.2 octene JSC 14/17 21/23 590/620 DOW ELITE 5400GS * Dow Metallocene. 0.916 1.0 123, 120 36.8 octene JSC 11.3/11.2 54/52 640/660 5118Q NKNKH C-Natta 0.916-0.920 2.5-3.5 122 44.6 butene+
hexene AO, TS, PPA 53/30 500/900

*The microstructure of the ethylene-octene-1 copolymer contains long-chain branches (C ₁₀₀ and more), obtained by the mechanism of reversible chain transfer

Additives: AO (antioxidant), PPA (processing additive), TS (thermal stabilizer)

As HDPE grafted with a functional monomer, the polyethylenes shown in Table 2 were used.

No. HDPE functionalized with maleic anhydride (MA) Content of grafted MA, % wt. PTR _190/2.16 , g/10 min M _W , g/mol Molecular weight distribution (MWD) Density, g/cm ³ 1. Fusabond 100 1.0 2.0 59000 5.0 0.960 2. Bondyram 5108 1.0 8.0 31000 5.5 0.961 3. BYC Scona TSPE 2102 2.0 0.35 37000 6.4 0.950 4. MA-HDPE-1 0.99 1.15 67000 6.1 0.960 5. MA-HDPE-2 1.11 0.65 70000 7.4 0.960 6. MA-HDPE-3 0.90 1.80 67000 6.8 0.960 7. MA-HDPE-4 0.82 4.01 63000 6.9 0.960

Table 2. Characteristics of HDPE functionalized with maleic anhydride.

The elastomer used is a copolymer of ethylene and butyl acrylate Elvaloy AC3427.

Vaseline oil is used as an optional additive.

Example 1 (comparative).

1 stage. As HDPE grafted with maleic anhydride, a product manufactured by Du Pont under the brand name Fusabond 100 with an MFI value of _190/2.16 = 2 and a grafted maleic anhydride content of 1% wt is used. (see Table 2).

Stage 2. In a paddle mixer prepare a mixture containing 15% wt. HDPE grafted with maleic anhydride (Fusabond 100; properties see table. 2), 80% wt. LLDPE (PE 5118Q) (properties see table 1), 5% wt. a copolymer of ethylene and butyl acrylate (for example, Elvaloy AC3427) and mixing is carried out for 2-10 minutes at a temperature of 10-50°C. The resulting mixture of components is processed in a twin-screw extruder LTE-20-44 at a maximum temperature in the cylinder zones of 240°C and a screw speed of 250 min ^-1 .

The resulting composition is characterized by an adhesive strength of 32.9 N/mm against steel at 23°C.

Example 2 (comparative).

Get the composition according to Example 1, except that as LLDPE using Sabic 318B (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 30.9 N/mm against steel at 23°C.

Example 3 (comparative)

Get the composition according to Example 1, except that as LLDPE using Sabic 118NJ (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 36.9 N/mm against steel at 23°C.

Example 4 (comparative)

Get the composition according to Example 1, except that as LLDPE using Daelim XP 9400 (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 29.0 N/mm against steel at 23°C.

Example 5 (comparative)

Get the composition according to Example 1, except that as LLDPE using Daelim XP 9200 (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 36.7 N/mm against steel at 23°C.

Example 6 (comparative)

A composition was prepared according to Example 1, except that DOW ELITE 5400GS was used as the LLDPE (see Table 1 for properties).

The resulting composition is characterized by an adhesive strength of 30.9 N/mm against steel at 23°C.

Example 7 (comparative)

A composition was prepared according to Example 1, except that the maleic anhydride grafted HDPE was Bondyram 5108 (see Table 2 for properties) and Daelim XP 9400 was used as LLDPE (see Table 1 for properties).

The resulting composition is characterized by adhesion adhesive strength of 23.6 N/mm in relation to steel at 23°C.

Example 8 (comparative)

Get the composition according to Example 7, except that as LLDPE using Daelim XP 9200 (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 28.6 N/mm against steel at 23°C.

Example 9 (comparative)

A composition is prepared according to Example 1, except that BIG Scona is used as maleic anhydride grafted HDPE (see Table 2 for properties) and Sabic 118NJ is used as LLDPE (see Table 1 for properties).

The resulting composition is characterized by an adhesive strength of 21.0 N/mm against steel at 23°C.

Example 10 (comparative)

1 stage. Synthesis of MA-HDPE-1 (see properties in Table 2).

In a paddle mixer prepare a mixture of the following components: up to 100% wt. HDPE grade PE2NT22-12 (Kazannefteorgsintez OJSC), 1.0% wt. maleic anhydride, 0.125% wt. organic peroxide Trigonox 301, 0.1% wt. vaseline oil. The resulting mixture is stirred for 2-10 minutes at a temperature of 10-50°C. Next, the finished mixture is processed in a twin-screw extruder LTE-20-44 at a maximum temperature in the cylinder zones of 240°C and a screw speed of 250 min ^-1 . The obtained strands are cooled in a water bath and granulated on the equipment attached to the extruder.

2 stage. In a paddle mixer prepare a mixture containing 15% wt. obtained in stage 1 HDPE, functionalized with maleic anhydride, 80.0% of the mass of LLDPE (PE 5118Q) and 5% wt. copolymer of ethylene and butyl acrylate (Elvaloy AC3427) and mixing is carried out for 2-10 minutes at a temperature of 10-50°C. The resulting mixture of components is processed in a twin-screw extruder LTE-20-44 at a maximum temperature in the cylinder zones of 240°C and a screw speed of 250 min ^-1 .

The resulting composition is characterized by an adhesive strength of 31.3 N/mm against steel at 23°C.

Example 11 (comparative)

Get the composition according to Example 10, except that as LLDPE using Sabic 318B (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 35.1 N/mm against steel at 23°C.

Example 12 (comparative)

Get the composition according to Example 10, except that as LLDPE using Sabic 118NJ (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 41.9 N/mm against steel at 23°C.

Example 13 (according to the invention)

A composition was prepared according to Example 10, except that DOWLEX 5056 was used as the LLDPE (see Table 1 for properties).

The resulting composition is characterized by an adhesive strength of 44.1 N/mm against steel at 23°C.

Example 14 (comparative)

Get the composition according to Example 10, except that as LLDPE using Daelim XP9400 (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 29.9 N/mm against steel at 23°C.

Example 15 (according to the invention)

Get the composition according to Example 10, except that as LLDPE using Daelim XP 9200 (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 42.9 N/mm against steel at 23°C.

Example 16 (according to the invention)

A composition was prepared according to Example 10, except that DOW ELITE 5400GS was used as the LLDPE (see Table 1 for properties).

The resulting composition is characterized by an adhesive strength of 58.7 N/mm against steel at 23°C.

Example 17 (comparative)

1 stage. Synthesis of MA-HDPE-2 (see properties in Table 2).

In a paddle mixer prepare a mixture of the following components: up to 100% wt. HDPE grade PE2NT22-12 (Kazannefteorgsintez OJSC), 1.0% wt. maleic anhydride, 0.20% wt. organic peroxide (Trigonox 301), 0.1% wt. vaseline oil. The resulting mixture is stirred for 2-10 minutes at a temperature of 10-50°C. Next, the finished mixture is processed in a twin-screw extruder LTE-20-44 at a maximum temperature in the cylinder zones of 240°C and a screw speed of 250 min ^-1 . The obtained strands are cooled in a water bath and granulated on the equipment attached to the extruder.

Stage 2. In a paddle mixer prepare a mixture containing 15% wt. obtained in stage 1 HDPE, functionalized with maleic anhydride, 80.0% wt. LLDPE (Daelim XP 9400) and 5% wt. copolymer of ethylene and butyl acrylate (Elvaloy AC3427) and mixing is carried out for 2-10 minutes at a temperature of 10-50°C. The resulting mixture of components is processed in a twin-screw extruder LTE-20-44 at a maximum temperature in the cylinder zones of 240°C and a screw speed of 250 min ^-1 .

The resulting composition is characterized by an adhesive strength of 29.3 N/mm against steel at 23°C.

Example 18 (comparative)

Get the composition according to Example 17, except that as LLDPE using Daelim XP 9200 (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 31.6 N/mm against steel at 23°C.

Example 19 (comparative)

1 stage. Synthesis of MA-HDPE-3 (see properties in Table 2).

In a paddle mixer prepare a mixture of the following components: up to 100% wt. HDPE grade PE2NT22-12 (Kazannefteorgsintez OJSC), 1.0% wt. maleic anhydride, 0.05% wt. organic peroxide (Trigonox 301), 0.1% wt. vaseline oil. The resulting mixture is stirred for 2-10 minutes at a temperature of 10-50°C. Next, the finished mixture is processed in a twin-screw extruder LTE-20-44 at a maximum temperature in the cylinder zones of 240°C and a screw speed of 250 min ^-1 . The obtained strands are cooled in a water bath and granulated on the equipment attached to the extruder.

Stage 2. In a paddle mixer prepare a mixture containing 15% wt. obtained in stage 1 HDPE, functionalized with maleic anhydride, 80.0% wt. LLDPE (Sabic 318B) and 5% wt. copolymer of ethylene and butyl acrylate (Elvaloy AC3427) and mixing is carried out for 2-10 minutes at a temperature of 10-50°C. The resulting mixture of components is processed in a twin-screw extruder LTE-20-44 at a maximum temperature of 240 °C in the cylinder zones and a screw speed of 250 min ^-1 .

The resulting composition is characterized by an adhesive strength of 32.4 N/mm against steel at 23°C.

Example 20 (comparative)

A composition was prepared according to Example 19, except that DOWLEX 5056 was used as the LLDPE (see Table 1 for properties).

The resulting composition is characterized by an adhesive strength of 32.4 N/mm against steel at 23°C.

Example 21 (comparative)

Get the composition according to Example 19, except that as LLDPE using Daelim XP 9400 (properties see table. 1).

The resulting composition is characterized by an adhesive strength of 24.3 N/mm against steel at 23°C.

Example 22 (comparative)

A composition was prepared according to Example 19, except that Daelim XP 9200 was used as the LLDPE (see Table 1 for properties).

The resulting composition is characterized by an adhesive strength of 36.8 N/mm against steel at 23°C.

Example 23 (comparative)

1 stage. Synthesis of MA-HDPE-4 (see properties in Table 2).

In a paddle mixer, a mixture is prepared from the following components: up to 100% wt. HDPE grade PE2NT22-12 (Kazannefteorgsintez OJSC), 1.0% wt. maleic anhydride, 0.02% wt. organic peroxide (Trigonox 301), 0.1% wt. vaseline oil. The resulting mixture is stirred for 2-10 minutes at a temperature of 10-50°C. Next, the finished mixture is processed in a twin-screw extruder LTE-20-44 at a maximum temperature in the cylinder zones of 240°C and a screw speed of 250 min ^-1 . The obtained strands are cooled in a water bath and granulated on the equipment attached to the extruder.

Stage 2. In a paddle mixer prepare a mixture containing 15% wt. obtained in stage 1 HDPE, functionalized with maleic anhydride, 80.0% wt. LLDPE (DOWLEX 5056) and 5% wt. copolymer of ethylene and butyl acrylate (Elvaloy AC3427) and mix for 2-10 minutes at a temperature of 10-50 °C. The resulting mixture of components is processed in a twin-screw extruder LTE-20-44 at a maximum temperature in the cylinder zones of 240°C and a screw speed of 250 min ^-1 .

The resulting composition is characterized by an adhesive strength of 27.2 N/mm against steel at 23°C.

Example 24 (comparative)

Get the composition according to Example 10, except that instead of LLDPE (PE 5118Q) used linear medium density polyethylene (Lumicene mPE) (see properties in table. 1).

The resulting composition is characterized by an adhesive strength of 31.5 N/mm against steel at 23°C.

Example 25 (comparative)

Get the composition according to Example 10, except that instead of LLDPE (PE 5118Q) used linear medium density polyethylene (DOWLEX 5066) (see properties in table 1).

The resulting composition is characterized by an adhesive strength of 30.1 N/mm against steel at 23°C.

Example 26 (according to the invention)

Get the composition according to Example 10, except that in the second stage of obtaining the adhesive composition instead of 15% wt. use 17% wt. MA-HDPE-1, and instead of 80% wt. use 78% wt. LLDPE (DOW ELITE 5400GS).

The resulting composition is characterized by an adhesive strength of 62.2 N/mm against steel at 23°C.

Example 27 (according to the invention)

Get the composition according to Example 16, except that in the second stage of obtaining the adhesive composition instead of 15% wt. use 20% wt. MA-HDPE-1, and instead of 80% wt. use 75% wt. LLDPE (DOW ELITE 5400GS).

The resulting composition is characterized by an adhesive strength of 52.0 N/mm against steel at 23°C.

Example 28 (comparative)

Get the composition according to Example 16, except that in the second stage of obtaining the adhesive composition instead of 15% wt. use 13% wt. MA-HDPE-1, and instead of 80% wt. use 82% wt. LLDPE (DOW ELITE 5400GS).

The resulting composition is characterized by an adhesive strength of 39.5 N/mm against steel at 23°C.

Example 29 (comparative)

Get the composition according to Example 16, except that in the second stage of obtaining the adhesive composition instead of 15% wt. use 23% wt. MA-HDPE-1, and instead of 80% wt. use 72% wt. LLDPE (DOW ELITE 5400GS).

The resulting composition is characterized by an adhesive strength of 35.8 N/mm against steel at 23°C.

Example 30 (comparative)

Get the composition according to Example 16, except that in the second stage of obtaining the adhesive composition does not use the elastomer Elvaloy AC 3427, and instead of 80% wt. use 85% wt. LLDPE (DOW ELITE 5400GS).

The resulting composition is characterized by an adhesive strength of 32.4 N/mm against steel at 23°C.

Table 3 shows the compositions of the PE compositions (Examples 1-30) and the results of determining their adhesive strength.

Table 3. Compositions and properties of adhesive compositions of polyethylene according to examples 1-30.

Components Composition, % wt. Example 1 (compar.) Example 2 (compar.) Example 3 (compar.) Example 4 (compar.) Example 5 (compar.) Example 6 (compar.) Example 7 (compar.) HDPE, grafted func. monomer
% wt. Fusabond 100, MFR _190/2.16 = 2.0 g/10 min 15.0 15.0 15.0 15.0 15.0 15.0 Bondyram 5108, MFR _190/2.16 = 8.0 g/10 min 15.0 BYC Scona, MFR _190/2.16 = 0.35 g/10 min MA-HDPE-1, MFR _190/2.16 = 1.15 g/10 min MA-HDPE-2, MFR _190/2.16 = 0.65 g/10 min MA-HDPE-3, MFR190/2.16= 1.80 g/10 min MA-HDPE-4, MFR190/2.16= 4.01 g/10 min LLDPE: d=0.916-0.919 g/cm3,
% wt. PE 5118Q, ZN, C ₄₊₆ , MFR=3.0 g/10 min 80.0 Sabic 318B, TsN, C ₄ , MFR= 2.8 g/10 min 80.0 Sabic 118NJ, TsN, C ₄ , MFR= 1.0 g/10 min 80.0 DOWLEX 5056, CN, C ₈ , MFR=1.1 g/10 min Daelim XP 9400, MTs, C _6, MFR=3.5 g/10 min 80.0 80.0 Daelim XP 9200, MTs, C _6, MFR=1.0 g/10 min 80.0 DOW ELITE 5400GS, MTs, _S8-100 , MFR=1.0 80.0 PE: d=0.934 g/cm3,
% wt. DOWLEX 5066, CN, C8, MFR=1.7 g/10 min Lumicene mPE, MC, C6, MFR= 0.9 g/10 min Elastomer, % wt. Elvaloy AC3427 (ethylene-butyl acrylate copolymer) 5 5 5 5 5 5 5 Composition properties: Adhesion strength to steel at 23ºС, N/mm 32.9 30.9 39.6 29.0 38.7 33.8 23.6 Adhesion strength to steel at 60ºС, N/mm 15.7 12.4 18.8 18.7 18.5 17.6 9.8 Adhesion strength to steel at 80ºС, N/mm 9.5 5.8 14.9 13.0 11.5 11.1 5.5

Continuation of Table 3

Components Composition, % wt. Example 8 (compar.) Example 9 (compar.) Example 10 (comp.) Example 11 (comp.) Example 12 Example 13 Example 14 (comp.) HDPE, grafted func. monomer
% wt. Fusabond 100, MFR _190/2.16 = 2.0 g/10 min Bondyram 5108, MFR _190/2.16 = 8.0 g/10 min 15.0 BYC Scona, MFR _190/2.16 = 0.35 g/10 min 15.0 MA-HDPE-1, MFR _190/2.16 = 1.15 g/10 min 15.0 15.0 15.0 15.0 15.0 MA-HDPE-2, MFR _190/2.16 = 0.65 g/10 min MA-HDPE-3, MFR190/2.16= 1.80 g/10 min MA-HDPE-4, MFR190/2.16= 4.01 g/10 min LLDPE: d=0.916-0.919 g/cm3,
% wt. PE 5118Q, ZN, C ₄₊₆ , MFR=3.0 g/10 min 80.0 Sabic 318B, TsN, C ₄ , MFR= 2.8 g/10 min 80.0 Sabic 118NJ, TsN, C ₄ , MFR= 1.0 g/10 min 80.0 80.0 DOWLEX 5056, CN, C ₈ , MFR=1.1 g/10 min 80.0 Daelim XP 9400, MTs, C _6, MFR=3.5 g/10 min 80.0 Daelim XP 9200, MTs, C _6, MFR=1.0 g/10 min 80.0 DOW ELITE 5400GS, MTs, _S8-100 , MFR=1.0 PE: d=0.934 g/cm3,
% wt. DOWLEX 5066, CN, C8, MFR=1.7 g/10 min Lumicene mPE, MC, C6, MFR= 0.9 g/10 min Elastomer, % wt. Elvaloy AC3427 (ethylene-butyl acrylate copolymer) 5 5 5 5 5 5 5 Composition properties: Adhesion strength to steel at 23ºС, N/mm 28.5 21.0 31.3 35.1 41.9 44.1 29.9 Adhesion strength to steel at 60ºС, N/mm 14.0 12.2 14.9 13.2 20.3 22.8 16.1 Adhesion strength to steel at 80ºС, N/mm 7.4 10.8 9.2 6.1 15.1 16.7 13.5

Continuation of Table 3

Components Composition, % wt. Example 15 Example 16 Example 17 (comp.) Example 18 (comp.) Example 19 (comp.) Example 20 (comp.) Example 21 (comp.) HDPE, grafted func. monomer
% wt. Fusabond 100, MFR _190/2.16 = 2.0 g/10 min Bondyram 5108, MFR _190/2.16 = 8.0 g/10 min BYC Scona, MFR _190/2.16 = 0.35 g/10 min MA-HDPE-1, MFR _190/2.16 = 1.15 g/10 min 15.0 15.0 MA-HDPE-2, MFR _190/2.16 = 0.65 g/10 min 15.0 15.0 MA-HDPE-3, MFR190/2.16= 1.80 g/10 min 15.0 15.0 15.0 MA-HDPE-4, MFR190/2.16= 4.01 g/10 min LLDPE: d=0.916-0.919 g/cm3,
% wt. PE 5118Q, ZN, C ₄₊₆ , MFR=3.0 g/10 min Sabic 318B, TsN, C ₄ , MFR= 2.8 g/10 min 80.0 Sabic 118NJ, TsN, C ₄ , MFR= 1.0 g/10 min DOWLEX 5056, CN, C ₈ , MFR=1.1 g/10 min 80.0 Daelim XP 9400, MTs, C _6, MFR=3.5 g/10 min 80.0 80.0 Daelim XP 9200, MTs, C _6, MFR=1.0 g/10 min 80.0 80.0 DOW ELITE 5400GS, MTs, _S8-100 , MFR=1.0 80.0 PE: d=0.934 g/cm3,
% wt. DOWLEX 5066, CN, C8, MFR=1.7 g/10 min Lumicene mPE, MC, C6, MFR= 0.9 g/10 min Elastomer, % wt. Elvaloy AC3427 (ethylene-butyl acrylate copolymer) 5 5 5 5 5 5 5 Composition properties: Adhesion strength to steel at 23ºС, N/mm 42.9 58.7 29.3 31.6 32.4 31.7 24.3 Adhesion strength to steel at 60ºС, N/mm 21.8 44.6 15.7 17.1 13.0 12.6 13.4 Adhesion strength to steel at 80ºС, N/mm 15.7 22.0 13.1 14.4 5.9 6.0 5.9

Continuation of Table 3

Components Composition, % wt. Example 22 (comp.) Example 23 (comp.) Example 24 (comp.) Example 25 (comp.) Example 26 Example 27 Example 28 (comp.) Example 29 (comp.) Example 30 (comp.) HDPE, grafted func. monomer
% wt. Fusabond 100, MFR _190/2.16 = 2.0 g/10 min Bondyram 5108, MFR _190/2.16 = 8.0 g/10 min BYC Scona, MFR _190/2.16 = 0.35 g/10 min MA-HDPE-1, MFR _190/2.16 = 1.15 g/10 min 15.0 15.0 17.0 20.0 13.0 23.0 15.0 MA-HDPE-2, MFR _190/2.16 = 0.65 g/10 min MA-HDPE-3, MFR190/2.16= 1.80 g/10 min 15.0 MA-HDPE-4, MFR190/2.16= 4.01 g/10 min 15.0 LLDPE: d=0.916-0.919 g/cm3,
% wt. PE 5118Q, ZN, C ₄₊₆ , MFR=3.0 g/10 min Sabic 318B, TsN, C ₄ , MFR= 2.8 g/10 min Sabic 118NJ, TsN, C ₄ , MFR= 1.0 g/10 min DOWLEX 5056, CN, C ₈ , MFR=1.1 g/10 min 80.0 Daelim XP 9400, MTs, C _6, MFR=3.5 g/10 min Daelim XP 9200, MTs, C _6, MFR=1.0 g/10 min 80.0 DOW ELITE 5400GS, MTs, _S8-100 , MFR=1.0 78.0 75.0 82.0 72.0 85.0 PE: d=0.934 g/cm3,
% wt. DOWLEX 5066, CN, C8, MFR=1.7 g/10 min 80.0 Lumicene mPE, MC, C6, MFR= 0.9 g/10 min 80.0 Elastomer, % wt. Elvaloy AC3427 (ethylene-butyl acrylate copolymer) 5 5 5 5 5 5 5 5 5 Composition properties: Adhesion strength to steel at 23ºС, N/mm 36.8 27.2 31.5 30.1 62.2 52.0 39.5 35.8 32.4 Adhesion strength to steel at 60ºС, N/mm 16.2 11.4 19.4 17.3 44.9 43.0 16.4 19.2 14.2 Adhesion strength to steel at 80ºС, N/mm 11.0 5.0 14.7 14.1 24.8 20.1 13.2 15.1 12.6

Thus, from the presented experimental data it can be seen that the claimed adhesive composition based on polyethylene has increased adhesive strength to steel and other polar substrates (protected materials) in comparison with the prototype and analogues, and has the following indicators: adhesion to steel at a level of 40 up 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 in adhesive strength of the presented composition are demonstrated by the examples given in Table 3.

The examples of the present invention show (examples 12, 13, 15, 16, 26 and 27) that the following conditions are required to achieve a technical result:

1) the densities of the polyethylenes used must differ significantly from each other; thus, the density of LLDPE should be 0.915 to 0.925 g/cm ³ , preferably 0.916 to 0.920 g/cm ³ , while the density of HDPE grafted with a functional monomer should be at least 0.955 g/cm ³ , preferably at least 0.960 g /cm ³ ;

2) MFR _190/2.16 of the polyethylenes should be in the range of 0.8 to 1.2 g/10 min, preferably 0.9 to 1.1 g/10 min;

3) LLDPE should be characterized by a branched structure, that is, the presence of side branches from the main hydrocarbon chain. An increase in the length of the hydrocarbon chain of the α-olefin used in the composition of LLDPE leads to an increase in adhesive strength, while the best technical result is achieved when using LLDPE, which is a copolymer of ethylene with octene-1 containing long-chain branches (C ₁₀₀ or more).

Claims (69)

1. An adhesive composition characterized by an adhesive 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, containing to the total weight of the composition the following components: A) from 59 to 82% wt. linear low density polyethylene (LLDPE) having a density in the range of 0.915 to 0.925 g/cm ³ and characterized by a branched hydrocarbon chain with side branches containing at least 4 carbon atoms; B) from 15 to 20% wt. high-density polyethylene (HDPE) grafted with a functional monomer - maleic anhydride, having a density of not less than 0.960 g/cm ³ , characterized by a molecular weight distribution value of not less than 5.9 and weight average molecular weights in the range from 65,000 to 70,000 g/mol; C) from 3 to 20% wt. an elastomer which is copolymers of ethylene with α-olefins and/or copolymers of ethylene with esters of unsaturated carboxylic acids; D) optional additives - up to 100%, while LLDPE and HDPE are characterized by an MFR _{of 190/2.16} in the range from 0.8 to 1.2 g/10 min, and the ratio of MFR of polyethylenes: LLDPE and HDPE grafted with a functional monomer is close to or equal to 1. 2. Adhesive composition according to claim 1, where the content of LLDPE in relation to the total weight of the composition is from 70 to 82% wt. 3. Adhesive composition according to claim 2, where the content of LLDPE in relation to the total weight of the composition is from 75 to 80% wt. 4. The adhesive composition according to claim 1, where the content of 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, where the content of HDPE grafted with a functional monomer, relative to the total weight of the composition, is from 15 to 17% wt. 6. Adhesive composition according to claim 1, where the elastomer content in relation to the total mass of the composition is from 5 to 15% wt. 7. Adhesive composition according to claim 6, where the elastomer content in relation to the total mass of the composition is from 5 to 10% wt. 8. Adhesive composition according to claim 1, where the elastomer is used in a weight ratio to HDPE grafted with a functional monomer, equal to from 1:1 to 1:5. 9. Adhesive composition according to claim 8, where the elastomer is used in a weight ratio to HDPE grafted with a functional monomer, equal to from 1:2 to 1:3. 10. Adhesive composition according to claim 1, wherein the density of the LLDPE is from 0.916 to 0.920 g/cm ³ . 11. Adhesive composition according to claim 1, wherein the MFR _190/2.16 for LLDPE and HDPE is in the range of 0.9 to 1.1 g/10 min. 12. An adhesive composition according to claim 1, wherein the molecular weight distribution for HDPE grafted with a functional monomer is at least 6.2. 13. The adhesive composition according to claim 1, wherein the LLDPE is a copolymer of ethylene with an α-olefin containing at least four carbon atoms. 14. Adhesive composition according to claim 13, where the content of α-olefin comonomer in LLDPE is from 2.5 to 8% wt. 15. The adhesive composition according to claim 14, where the content of α-olefin comonomer in LLDPE is from 3 to 6% wt. 16. The adhesive composition according to claim 15, where the content of α-olefin comonomer in LLDPE is from 3.5 to 5% wt. 17. Adhesive composition according to claim 1, where LLDPE is a polyethylene, which is characterized by the presence of long-chain branches of hydrocarbon chains - side branches containing 100 or more carbon atoms. 18. Adhesive composition according to claim 1, where LLDPE is a polyethylene, which is characterized by the presence of long-chain branches of hydrocarbon chains - side branches containing 100 or more carbon atoms, obtained by a reversible chain transfer mechanism. 19. The adhesive composition according to claim 1, where the HDPE grafted with a functional monomer is an ethylene homopolymer, to the macromolecule of which a functional monomer, maleic anhydride, is grafted. 20. The adhesive composition according to claim 1, wherein the amount of functional monomer grafted onto the HDPE is 0.5 to 2% by weight, based on the total weight of the HDPE grafted with the functional monomer. 21. Adhesive composition according to claim 20, where the amount of functional monomer grafted onto HDPE is from 1.0 to 1.5% wt. in relation to the total mass of HDPE grafted with a functional monomer. 22. The adhesive composition according to claim 1, wherein the HDPE grafted with the functional monomer is obtained by reactive extrusion of the HDPE and the functional monomer in the presence or absence of a radical initiator. 23. The adhesive composition according to claim 22, wherein the radical initiator is an organic peroxide. 24. An adhesive composition according to claim 23, wherein the amount of organic peroxide is from 0.01 to 0.4% by weight, most preferably from 0.05 to 0.15% by weight, based on the total weight of the composition. 25. Adhesive composition according to claim 1, where the elastomer is a copolymer of ethylene with α-olefins containing from 4 to 8 carbon atoms, and/or a copolymer of ethylene with esters of unsaturated carboxylic acids. 26. The adhesive composition according to claim 25, where the copolymers of ethylene with esters of unsaturated carboxylic acids are random copolymers containing ester comonomer in an amount of from 5 to 40% wt. 27. An adhesive composition according to claim 26, wherein said unsaturated carboxylic acid ester is selected from alkyl acrylate and/or alkyl methacrylate, where alkyl contains up to 24 carbon atoms. 28. Adhesive composition according to claim 1, where other additives include antioxidants, UV absorbers, antistatic agents, crystallizing agents, fillers, lubricants, flame retardants. 29. Adhesive composition according to claim 1, where other additives are used in an amount of from 0 to 1% wt., preferably from 0.1 to 0.5% wt. 30. A method for producing an adhesive composition, characterized by an adhesive 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, including stages: obtaining HDPE grafted with a functional monomer by mixing HDPE and a functional monomer, and mixing and processing into a homogeneous melt mixture obtained in the previous stage of HDPE, grafted with a functional monomer, LLDPE and elastomer, in which these stages are carried out in relation to the following components, taken in relation to the total mass of the composition in the amount of: A) from 59 to 82% wt. linear low density polyethylene (LLDPE) having a density in the range of 0.915 to 0.925 g/cm ³ and characterized by a branched hydrocarbon chain with side branches containing at least 4 carbon atoms; B) from 15 to 20% wt. high-density polyethylene (HDPE) grafted with a functional monomer - maleic anhydride, having a density of not less than 0.960 g/cm ³ , characterized by a molecular weight distribution value of not less than 5.9 and weight average molecular weights in the range from 65,000 to 70,000 g/mol; C) from 3 to 20% wt. an elastomer which is copolymers of ethylene with α-olefins and/or copolymers of ethylene with esters of unsaturated carboxylic acids; D) optional additives - up to 100%, where LLDPE and HDPE are characterized by an MFR _{of 190/2.16} in the range from 0.8 to 1.2 g/10 min, and the ratio of MFR of polyethylenes: LLDPE and HDPE grafted with a functional monomer is close to or equal to 1. 31. The method of obtaining the composition according to p. 30, where the content of LLDPE in relation to the total weight of the composition is from 70 to 82% wt. 32. The method of obtaining the composition according to p. 31, where the content of LLDPE in relation to the total weight of the composition is from 75 to 80% wt. 33. The method of obtaining a composition according to p. 30, where the content of HDPE grafted with a functional monomer, relative to the total weight of the composition is from 15 to 18% wt. 34. The method of obtaining a composition according to p. 33, where the content of HDPE grafted with a functional monomer, relative to the total weight of the composition is from 15 to 17% wt. 35. The method of obtaining a composition according to p. 30, where the elastomer content in relation to the total mass of the composition is from 5 to 15% wt. 36. The method of obtaining a composition according to p. 35, where the elastomer content in relation to the total mass of the composition is from 5 to 10% wt. 37. The method of obtaining a composition according to claim 30, where the elastomer is used in a mass ratio to HDPE grafted with a functional monomer, equal to from 1:1 to 1:5. 38. The method of obtaining a composition according to p. 37, where the elastomer is used in a mass ratio to HDPE grafted with a functional monomer, equal to from 1:2 to 1:3. 39. The method of obtaining a composition according to p. 30, where the density of LLDPE is from 0.916 to 0.920 g/cm ³ . 40. A method for preparing a composition according to claim 30, wherein the MFR _190/2.16 for LLDPE and HDPE is in the range of 0.9 to 1.1 g/10 min. 41. A process for preparing a composition according to claim 30, wherein the molecular weight distribution for HDPE grafted with a functional monomer is at least 6.2. 42. The method of obtaining a composition according to claim 30, where said LLDPE is a polyethylene, which is characterized by the presence of long-chain branches of hydrocarbon chains - side branches containing 100 or more carbon atoms. 43. A method for producing a composition according to claim 30, where said LLDPE is a polyethylene, which is characterized by the presence of long-chain branches of hydrocarbon chains - side branches containing 100 or more carbon atoms, obtained by a reversible chain transfer mechanism. 44. The method of obtaining a composition according to claim 30, where the amount of functional monomer grafted onto HDPE is from 2 to 0.5% by weight, relative to the total weight of HDPE grafted with functional monomer. 45. The method of obtaining a composition according to p. 30, where the amount of functional monomer grafted onto HDPE is from 1.5 to 1.0 wt.%, relative to the total weight of HDPE grafted with functional monomer. 46. The method of obtaining a composition according to claim 30, where other additives include antioxidants, UV absorbers, antistatic agents, crystallizing agents, fillers, lubricants, flame retardants. 47. The method of obtaining a composition according to p. 30, where other additives are used in an amount of from 0 to 1% wt., preferably from 0.1 to 0.5% wt. 48. A method for preparing a composition according to claim 30, including the step of mixing HDPE and a functional monomer in the presence or absence of a radical initiator. 49. The method of obtaining the composition according to p. 30, where the HDPE and the functional monomer are mixed for a period of time from 1 to 20 minutes, preferably from 2 to 10 minutes at a temperature of from 10 to 100°C, preferably from 20 to 50°C. 50. A method for preparing a composition according to claim 30, wherein other optional additives are added before or after functional monomer grafting. 51. The method of obtaining a composition according to p. 30, including the stage of mixing HDPE grafted with a functional monomer with LLDPE and elastomer for a period of time from 1 to 20 minutes, preferably from 2 to 10 minutes at a temperature of from 10 to 100 ° C, preferably from 20 to 50°C. 52. The method of obtaining a composition according to p. 30, where processing into a homogeneous melt is carried out at a temperature of from 190 to 240°C, preferably from 220 to 230°C. 53. The method of obtaining a composition according to claim 30, where mixing and processing into a homogeneous melt is carried out using mixing equipment and an extruder. 54. The use of an adhesive composition based on polyethylene according to any one of paragraphs. 1-29, characterized by adhesion 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, as an adhesive layer in multilayer coatings. 55. Application according to claim 54, where the coating is a multilayer insulation, in particular, pipes intended for the construction of gas and oil pipelines. 56. A pipe provided with a multilayer insulation containing an adhesive layer comprising an adhesive composition based on polyethylene according to any one of paragraphs. 1-29.