RU2792564C1 - Polyethylene powder composition for protection against ice and corrosion of ships' hulls and steel pipelines and method for its production - Google Patents

Abstract

FIELD: thermoplastic powder paint.

SUBSTANCE: method for producing a powder polyethylene composition for protection against icing and corrosion of ship hulls and steel pipelines includes preliminary production of a granular composition and subsequent mechanical grinding of the granulate to a particle size of 150-250 microns. The granular composition includes bimodal high-density polyethylene, high-density cast polyethylene, malleated cast high-density polyethylene, ethylene-octene copolymer, styrene-ethylene-butylene-styrene block copolymer, dye superconcentrate based on cast linear polyethylene, primary phenol-type antioxidant, secondary phosphite antioxidant, light stabilizer and fluoropolymer.

EFFECT: invention makes it possible to increase the rigidity, wear resistance, strength and adhesion of a coating based on a powdered polyethylene composition.

1 cl, 2 dwg, 2 tbl, 7 ex

Description

The invention relates to the creation of a new type of thermoplastic powder paint, which is a multimodal polyethylene composition, and is intended for protection against icing and corrosion of ship hulls, steel gas pipelines and oil pipelines. To date, the protection of ship hulls is carried out with the help of special paint coatings with low surface energy and, accordingly, reduced adhesion to ice. In practice, about 45% of offshore structures have the problem of discontinuity of the paint layer, as a result of which the development of corrosion damage is observed. This is due to the low corrosion resistance of the coating, the minimum thickness of the coating material layer and its low elasticity (brittleness, delamination, etc.). Along with these disadvantages, such coatings have instability of hydrophobicity, which decreases when they are used in water and atmospheric conditions. Thus, the problems of creating stable protective anti-icing coatings for ship hulls are far from being solved.

The problem of icing and corrosion of steel pipelines is qualitatively solved only for straight segments. In the factory, three or two-layer protective coatings based on polyethylene compositions are applied by extrusion. Pipes with a factory coating are delivered to the installation site and connected by welding. Welded joints are protected at the installation site, where it is impossible to use factory technologies for applying protective coatings and, accordingly, materials developed for them. The materials currently used to protect steel pipelines at the installation site are different from those applied at the factory. So the main solution for protecting welded joints at the pipeline installation sites are heat-shrinkable cuffs, which do not provide the required adhesion in the cuff overlap zone to the factory coating of pipes, which leads to premature corrosion and, accordingly, a reduction in the service life of the pipeline. Another aspect in improving the quality of protective coatings for steel pipelines is the application of protective coatings to individual and curly parts of pipelines, such as: fittings, tees, valves, condensate drains, transitions, curved bends, etc. The application of a protective layer on such parts is carried out both in the factory and and in the field. However, the use of factory high-performance technology for continuous application of a protective coating to such parts by extrusion is impossible due to the irregular geometric shape of these parts. Therefore, a different technology is used for protective coatings of shaped products, and other materials are used: polyurethanes and epoxy resins. Due to the heterogeneity of these materials with the nature of the main coating, problems arise at the joints, leading to a decrease in the reliability of the protective coating and, as a result, a reduction in its service life. In addition, the performance of protective coatings made of polyurethanes and epoxy resins is significantly lower than the same properties of the extrusion coating, which reduces the life of the pipeline as a whole. The situation can be significantly improved by creating materials for protective coatings of welded joints and fittings on the same basis as the main factory coating, as well as choosing the appropriate technology.

The prior art method for producing an adhesive coating applied to metal surfaces by plasma spraying of a polymer layer based on secondary polyethylene stabilized with 5(6)-amino-2(4-aminophenyl) benzimidazole (RU 2051986 C1, 10.01.1996). It is noted that the polymer composition additionally contains carbon black and low molecular weight polyethylene.

Patent RU 2387736 C2, 04/27/2010 discloses a powder material for thermal spraying of polymer coatings containing polyethylene as a base and powder of a refractory compound, and it additionally contains Al2O3 with a particle size of 40-50 μm as a filler, polyethylene is a powder of ultra-high molecular weight polyethylene with a viscosity average molecular weight of n⋅106 g/mol, where n is 2 or more, and the powder of the refractory compound is a modifier and is a nanodispersed powder with a particle size of 50-300 nm.

The closest analogue of the invention is a powder composition based on polyethylene known from RU 2757483, 10/18/2021 for coating metal, fiberglass and concrete structures, characterized in that the composition contains component (A), which is an ethylene copolymer with a density of 0.910-0.945 g/cm3, alpha-olefins containing from 3 to 8 carbon atoms in the chain are used as comonomers for the copolymer, the melt flow index of component (A) is 5.0 - 100.0 g/10 min at a temperature of 190 ° C and a load of 2.16 kgf , the content of component (A) is 28-93.9 wt.%, component (B), which is a copolymer of ethylene with a density of 0.930-0.960 g/cm3 with grafted functional groups of carboxylic acids, alpha-olefins containing from 3 to 8 carbon atoms in the chain, the functional groups of carboxylic acids are maleic acid, or fumaric acid, or itaconic acid, or acrylic acid, containing the functional groups of carboxylic acids is 0.1-1.0 wt.%, the melt flow index of the component (B) is 0.1-35 g/10 min at a temperature of 190°C and a load of 2.16 kgf, the content of the component (B ) is 5-38 wt.%, component (C), which is an ethylene-based elastomer with a density of 0.860-0.890 g/cm3, whose comonomer is alpha-olefins containing from 3 to 8 carbon atoms in the chain, the melt flow index component (C) is 5.0-45 g / 10 min at a temperature of 190 ° C and a load of 2.16 kgf, the content of component (C) is 1-32 wt.%, component (D), which is a complex of stabilizers from the classes of hindered phenolic antioxidants and phosphite antioxidants in a ratio of 1:4 to 3:1, respectively, while the content of component (D) is 0.1-2.0 wt.%.

The disadvantage of the known composition is not sufficiently high rigidity, wear resistance and strength characteristics, as well as insufficient resistance of the coating to cracking under the influence of the environment. In addition, the powder composition known from RU 2757483, 10/18/2021 is applied by immersion in a fluidized bed (FB) and it is not applicable for coating by flame spraying.

The present invention solves the problems described above.

The problem to be solved when creating the claimed group of inventions is to obtain a powder polyethylene composition for protection against icing and corrosion of ship hulls and pipelines.

At the same time, the technical result achieved in solving the problem is to create a technology for the production of a powder polyethylene composition for obtaining a protective coating by flame spraying that meets the requirements of OTT-25.220.60-KTN-103-15, STO Gazprom 2-2.3-130-2007 and ND No. 2-020101-124. The coating obtained using the claimed composition has high rates of rigidity, wear resistance, strength and adhesion.

The specified technical result is achieved by creating a multimodal polyethylene composition modified with a special group of elastomers, as well as having a complex of stabilizers and external lubricants, which makes it possible to use this powder composition in flame spraying.

The method for producing a powder polyethylene composition for anti-icing and corrosion protection of ship hulls and steel pipelines includes the following steps:

a) obtaining a composition in granular form by melt mixing in a twin-screw extruder, followed by cooling and granulation of a homogeneous melt of the following raw materials:

• bimodal high density polyethylene with a melt flow rate of 0.28-0.32 g/10 min at a temperature of 190°C and a load of 2.16 kgf;

• molded high-density polyethylene with a narrow molecular weight distribution and a melt flow index of 28.0-32.0 g/10 min at a temperature of 190°C and a load of 2.16 kgf;

• maleized cast high-density polyethylene with a narrow molecular weight distribution, melt flow index 16.0-20.0 g/10 min at a temperature of 190°C and a load of 2.16 kgf and 0.9-1.1 wt.% grafted maleic groups;

• ethylene-octene copolymer with a melt flow index of 4.0-6.0 g/10 min at a temperature of 190°C and a load of 2.16 kgf, hardness of 68-72 Shore A and a melting point of 55-60°C;

• block copolymer "styrene-ethylene-butylene-styrene" (SEBS) with styrene content of 31-34 wt.% and viscosity in toluene solution (10 wt.%) at 25°C - 2000-6000 MPa⋅s;

• dye superconcentrate based on cast linear polyethylene having a melt flow rate of 48.0 - 52.0 g/10 min at a temperature of 190°C and a load of 2.16 kgf;

• primary antioxidant of the phenolic type, which is tetrakismethylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate);

• secondary phosphite antioxidant, which is tris-(2,4-di-tert-butylphenyl)phosphite;

• light stabilizer poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4- piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]];

• fluoropolymer having a melt flow rate of 6.0 - 14.0 g/10 min at a temperature of 265°C and a load of 5.0 kgf and a melting point of 110-126°C;

b) subsequent mechanical grinding of the obtained granules of the composition in a disk mill to an average particle size of 150-250 microns.

The method is also characterized by the fact that these raw materials are taken in the following ratio, wt. %:

bimodal high density polyethylene - 16.9;

molded high-density polyethylene - 59.5-59.9;

maleized cast polyethylene of high density - 4.8-5.2;

ethylene-octene copolymer - 4.9-5.1;

block copolymer "styrene-ethylene-butylene-styrene" - 9.9-10.1;

dye superconcentrate - 1.5-2.0;

primary antioxidant - 0.3-0.4;

secondary antioxidant - 0.6-0.8;

light stabilizer - 0.4-0.6;

fluoropolymer - 0.1.

At any intermediate value of the indicated concentration ranges of the components, the technical result is achieved.

Table 1 shows the formulations of the powder polyethylene composition, which will achieve the final positive technical result.

Table 1. No. Percentage of components in formulations (% wt.) Bimodal high density polyethylene Molded high density polyethylene Maleized high density polyethylene Ethylene-octene copolymer Styrene-ethylene-butylene-styrene Color Masterbatch Primary Antioxidant secondary antioxidant light stabilizer External lubricant (fluoropolymer) 1 16.9 59.9 4.8 5 10 2 0.3 0.6 0.4 0.1 2 16.9 59.9 4.8 5 10 1.5 0.4 0.8 0.6 0.1 3 16.9 59.9 4.8 4.9 10.1 2 0.3 0.6 0.4 0.1 4 16.9 59.9 4.8 4.9 10.1 1.5 0.4 0.8 0.6 0.1 5 16.9 59.9 4.8 5.1 9.9 2 0.3 0.6 0.4 0.1 6 16.9 59.9 4.8 5.1 9.9 1.5 0.4 0.8 0.6 0.1 7 16.9 59.8 4.9 5 10 2 0.3 0.6 0.4 0.1 8 16.9 59.8 4.9 5 10 1.5 0.4 0.8 0.6 0.1 9 16.9 59.8 4.9 4.9 10.1 2 0.3 0.6 0.4 0.1 10 16.9 59.8 4.9 4.9 10.1 1.5 0.4 0.8 0.6 0.1 eleven 16.9 59.8 4.9 5.1 9.9 2 0.3 0.6 0.4 0.1 12 16.9 59.8 4.9 5.1 9.9 1.5 0.4 0.8 0.6 0.1 13 16.9 59.7 5.0 5 10 2 0.3 0.6 0.4 0.1 14 16.9 59.7 5.0 5 10 1.7 0.4 0.8 0.6 0.1 15 16.9 59.7 5.0 4.9 10.1 2 0.3 0.6 0.4 0.1 16 16.9 59.7 5.0 4.9 10.1 1.7 0.4 0.8 0.6 0.1 17 16.9 59.7 5.0 5.1 9.9 2 0.3 0.6 0.4 0.1 18 16.9 59.7 5.0 5.1 9.9 1.7 0.4 0.8 0.6 0.1 19 16.9 59.6 5.1 5 10 2 0.3 0.6 0.4 0.1 20 16.9 59.6 5.1 5 10 1.7 0.4 0.8 0.6 0.1 21 16.9 59.6 5.1 4.9 10.1 2 0.3 0.6 0.4 0.1 22 16.9 59.6 5.1 4.9 10.1 1.7 0.3 0.6 0.6 0.1 23 16.9 59.6 5.1 5.1 9.9 2 0.4 0.8 0.4 0.1 24 16.9 59.6 5.1 5.1 9.9 1.7 0.3 0.6 0.6 0.1 25 16.9 59.5 5.2 5 10 2 0.3 0.6 0.4 0.1 26 16.9 59.5 5.2 5 10 1.5 0.4 0.8 0.6 0.1 27 16.9 59.5 5.2 4.9 10.1 2 0.3 0.6 0.4 0.1 28 16.9 59.5 5.2 4.9 10.1 1.5 0.4 0.8 0.6 0.1 29 16.9 59.5 5.2 5.1 9.9 2 0.3 0.6 0.4 0.1 thirty 16.9 59.5 5.2 5.1 9.9 1.5 0.4 0.8 0.6 0.1

The method for obtaining a powder polyethylene composition according to the invention is illustrated in Fig.1, which shows a diagram of such a method.

The possibility of achieving the desired result lies in the creation of a multimodal composition based on bimodal high-density polyethylene and molded high-density polyethylene with a narrow MWD, modified with maleized molded high-density polyethylene with a narrow MWD, a special group of elastomers and having a complex of stabilizers and external lubricant. In this case, each component performs its role:

- bimodal high-density polyethylene with a melt flow rate of 0.27-0.33 g/10 min (190 ° C, 2.16 kgf) provides the coating with high rigidity, wear resistance, strength characteristics, as well as resistance to cracking under the influence of the environment ;

- cast high-density polyethylene with a narrow molecular weight distribution and a melt flow rate of 27.0-33.0 g/10 min (190 ° C, 2.16 kgf) provides the coating with high rigidity, wear resistance, tensile yield strength, and also high manufacturability in flame spraying of the powder composition;

- maleized cast high-density polyethylene with a narrow molecular weight distribution, melt flow rate of 16.0-20.0 g/10 min (190 °C, 2.16 kgf) and 0.9-1.1% of grafted maleic groups provides without losing the basic properties of the multimodal composition, high adhesion of the coating due to a chemical reaction with an epoxy primer previously applied to the sides of ships or steel pipelines;

- the group of elastomers consists of:

• ethylene-octene copolymer with a melt flow index of 4.0-6.0 g/10 min (190 °C, 2.16 kgf), hardness - 68-72 Shore A and melting point - 55-60 °C;

• - block copolymer "styrene-ethylene-butylene-styrene" (SEBS) with styrene content of 31-34% and viscosity in toluene solution (10% /25 °C) - 2000-6000 MPa⋅s.

Both components provide the required elongation at break at -45 °C, and also give the composition the ability to strengthen in tension and achieve the required tensile strength at room temperature, which is not typical for molded high-density polyethylene grades. The presence of two elastomers in the formulation is due to the fact that they compensate for the negative impact of each elastomer individually. SEBS greatly increases the viscosity of the composition, which is unacceptable for flame spraying, and the ethylene-octene copolymer greatly reduces the Vicat softening point. Properly chosen ratio of these two elastomers minimizes these disadvantages.

- the color of the composition for protecting pipelines is black, and for protecting the sides of ships it is determined by the customer. The coloring of the composition is carried out through superconcentrates based on cast linear polyethylene, which has a melt flow rate (190 ° C, 2.16 kgf) - 48.0 - 52.0 g / 10 min, in order to preserve the properties of the multimodal composition as much as possible;

- a complex of stabilizers consists of a primary phenol-type antioxidant with the chemical formula Tetrakismethylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate), which is responsible both for stabilizing the composition during processing and for long-term operation of the coating, a secondary phosphite antioxidant with chemical formula tris-(2,4-di-tert-butylphenyl)phosphite, which is responsible for stabilizing the composition during processing, as well as a light stabilizer with the chemical formula poly[[6-[(1,1,3,3-tetramethylbutyl)amino]- 1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl- 4-piperidinyl)imino]] needed to protect the coating from the negative effects of UV exposure.

- a fluoropolymer was chosen as an external lubricant, having a melt flow index (265 °C, 5.0 kgf) - 6.0 - 14.0 g/10 min and a melting point - 110-126 °C. On the one hand, it does not worsen the original properties of the multimodal composition, and on the other:

• acts as a processing additive (facilitates the processing of the composition during compounding, reduces the formation of deposits on the screws and the extruder barrel, accelerates the transition from color to color);

• significantly reduces the coefficient of sliding friction on ice due to the formation of a fluoroplastic film on the surface of the coating;

• increases the thermal stability of the polyethylene powder composition, which is especially important for flame spraying.

The salient features of the composition are:

• the basis of the composition is a mixture of bimodal high density polyethylene and molded high density polyethylene with a narrow molecular weight distribution, forming a multimodal composition;

• the presence in the recipe of a group of elastomers, which, on the one hand, give the composition the necessary relative elongation at break at -45°C and strength at break at room temperature, and on the other hand, compensate for the negative effect of each of them on the Vicat softening temperature and the melt flow index ;

• a complex of stabilizers with increased concentrations of primary and secondary antioxidants in the composition to protect the composition from undesirable oxidative effects caused by flame exposure during flame spraying of the coating;

• Fluoroplastic external lubrication to provide the required coefficient of sliding friction on ice and increase the thermal stability of the composition required for flame spraying of the coating.

The process of creating a powder polyethylene composition occurs in two stages. With reference to Figure 1, in the first stage, a composition is obtained in granular form by mixing the initial raw materials in the melt in an extruder. Each component contributes both to the complex of target properties of the finished product and to the technology.

All components must be qualitatively distributed in the mass, so it is important to observe the temperature-shift technological regime during compounding. This goal is served by the requirements for the used compounding equipment, the configuration of its elements.

A mixing extruder for obtaining the claimed composition can be a twin screw extruder with an L/D of at least 48 and a number of zones of at least 12, equipped with systems for dosing components, vacuum degassing, melt cooling and granulation of the finished material. All components are fed into the first loading zone of the extruder at a screw speed of 300÷400 rpm. The temperature profile of the extruder is as follows:

zone number Z0 Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Z9 Z10 Z11 Die T ass. cool. 120 140 150 160 170 180 190 200 200 200 200 200

The quality of mixing is most affected by the configuration (assembly) of the screws. The most optimal screw configuration is shown in Fig. 2.

With reference to Figure 1, in the second stage, mechanical grinding of the granular composition obtained in the first stage is carried out. Grinding can be carried out using a disk mill - a granular polyethylene composition is fed into the grinding chamber into the gap between the rotating and stationary disks, where, due to the cutting effect between the toothed segments of the disks, the material is crushed. When the particles reach the required size, they are carried out of the grinding chamber by the air flow created by the blower. In this case, the air flow, in addition to transporting powder particles, additionally cools the material and grinding discs, which makes it possible to avoid unacceptable softening of the material. The blower sends the crushed material to the cyclone separator, from which air and dust are sent to the dust collector bag for dust removal, and the polyethylene powder composition enters the classifier with meshes having a mesh size of 400 microns. This size provides maximum performance for the average particle size D50 - 150-250 microns. Particles larger than the mesh cells are sent to the grinding chamber for re-grinding.

The claimed method is confirmed by the following examples:

Example 1

Raw component Concentration, % HDPE Sabic CC3054 59.7 HDPE HD03580SB 16.9 Metalen F-10180 5 Lucene LC 670 5 Sinopec YH-503 10 Basco PF1110/01-LP 2 Songnox 1010 0.3 Irgafos 168 0.6 Chimassorb 944 FDL 0.4 Dynamar FX5911 0.1

Example 2

Raw component Concentration, % HDPE Sabic CC3054 59.7 HDPE HD03580SB 16.9 Metalen F-10180 5 Lucene LC 670 5 Sinopec YH-503 10 Basco PF1210/02-LP 2 Songnox 1010 0.3 Irgafos 168 0.6 Chimassorb 944 FDL 0.4 Dynamar FX5911 0.1

Example 3

Raw component Concentration, % HDPE Sabic CC3054 59.7 HDPE HD03580SB 16.9 Metalen F-10180 5 Lucene LC 670 5 Sinopec YH-503 10 Basco PF1310/01-LP 2 Songnox 1010 0.3 Irgafos 168 0.6 Chimassorb 944 FDL 0.4 Dynamar FX5911 0.1

Example 4

Raw component Concentration, % HDPE Sabic CC3054 59.7 HDPE HD03580SB 16.9 Metalen F-10180 5 Lucene LC 670 5 Sinopec YH-503 10 Basco PF1410/08-LP 2 Songnox 1010 0.3 Irgafos 168 0.6 Chimassorb 944 FDL 0.4 Dynamar FX5911 0.1

Example 5

Raw component Concentration, % HDPE Sabic CC3054 59.7 HDPE HD03580SB 16.9 Metalen F-10180 5 Lucene LC 670 5 Sinopec YH-503 10 Basco PF1510/08-LP 2 Songnox 1010 0.3 Irgafos 168 0.6 Chimassorb 944 FDL 0.4 Dynamar FX5911 0.1

Example 6

Raw component Concentration, % HDPE Sabic CC3054 59.7 HDPE HD03580SB 16.9 Metalen F-10180 5 Lucene LC 670 5 Sinopec YH-503 10 Basco PF1810/64-LP 2 Songnox 1010 0.3 Irgafos 168 0.6 Chimassorb 944 FDL 0.4 Dynamar FX5911 0.1

Example 7

Raw component Concentration, % HDPE Sabic CC3054 59.7 HDPE HD03580SB 16.9 Metalen F-10180 5 Lucene LC 670 5 Sinopec YH-503 10 Basco PF1910/22-LP 2 Songnox 1010 0.3 Irgafos 168 0.6 Chimassorb 944 FDL 0.4 Dynamar FX5911 0.1

The obtained powder compositions for examples No. 1-7 are applied to pre-prepared steel plates with a size of 150 mm * 70 mm * 3 mm.

Surface preparation consists of several subsequent stages:

• degreasing;

• sandblasting;

• dedusting;

• passivation;

• application of epoxy primer.

Degreasing of the metal surface is carried out using a soft lint-free cloth or cotton swab dipped in a solvent to a degree of not more than 1 in accordance with GOST 9.402-2004. Tetrachlorethylene, white spirit, nefras-C 50/170 or acetone are used as solvents. After processing, the plate is kept for 15 minutes under forced exhaust ventilation.

Surface cleaning from scale, rust and heavy contaminants is carried out mechanically, namely by air-abrasive method using a sandblaster. The work is carried out in an uninhabited sandblasting chamber with pre-activated ventilation, individual lighting and a cyclone air filtration system. When abrasive processing, either cooper slag or nickel slag is used. After abrasive treatment, the surface must be free of sharp protrusions, burrs, metal spatter, slag and other unacceptable surface defects. The degree of cleaning must be at least Sa 2 1/2 in accordance with GOST R ISO 8501-1-2014, and the surface roughness - 40 ÷ 90 microns in accordance with ISO 8503-4:2012.

After abrasive treatment, the removal of residual dust with compressed air from the surface should be carried out. The dust content class should be no more than the third according to ISO 8502-3:2017.

To increase the adhesion of the coating, chemical treatment (passivation) of the surface is carried out with chromate, phosphate or chromate-phosphate solutions. The applied layer should be uniform without streaks and gaps.

During the entire technological cycle of metal surface preparation and application of a protective coating, the relative humidity of the air should not exceed 80%, and the temperature in the room should be at least 15 °C.

The prepared metal plates are thermostated in a heating cabinet at a temperature of 250 °C for 13 ÷ 15 minutes until the surface temperature of the steel plate reaches 210 ÷ 230 °C.

The heated plates are transferred to the application chamber, where the powder epoxy primer KCC Karumel EX4413-L300 B/Green (II) or its equivalent is applied using an electrostatic application unit. In this case, at the time of application, the surface temperature of the steel plates should be 180 ÷ 220 °C. The minimum thickness of the epoxy primer layer must be at least 60 µm.

The application of a powder polyethylene composition is carried out using a flame spraying unit. The prepared metal plate is placed on a stand in the application chamber. The application of a powder polyethylene composition is carried out by a burner placed at a distance of 500 ÷ 650 mm from the surface. The burner is moved in the plane of the plate at a speed of approximately 20 ÷ 30 mm/sec. At a deposition rate of 20 ÷ 30 mm/sec, the thickness of the coating layer applied in 1 layer is 200 ÷ 250 µm. After obtaining a coating thickness of 3.0 - 3.5 mm on the entire surface of the steel plate, the sample is cooled. Samples are placed in a container with water at room temperature or a thermostat that maintains a water temperature of 20 °C. The test results are shown in Table 2.

table 2 Property Norm Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Average particle size, microns - 225 228 218 220 232 225 220 Color - RAL 3020 RAL 2008 RAL 1016 RAL 6005 RAL 5005 RAL 7046 RAL 9005 Density, g / cm ³ - 0.951 0.951 0.951 0.951 0.951 0.951 0.951 Melt flow rate, g/10 min - 5.4 5.4 5.3 5.4 5.5 5.3 5.4 Shore hardness D, arb. - 55 55 55 55 55 55 55 Brittleness temperature, °С Not higher than -70 Below -70 Below -70 Below -70 Below -70 Below -70 Below -70 Below -70 Vicat softening point, °C At least 105 115 115 115 115 115 115 115 Burst resistance at +23 °С/+60 °С, mm Not more than 0.15 / not more than 0.2 0.05/0.11 0.05/0.11 0.05/0.11 0.05/0.11 0.05/0.11 0.05/0.11 0.05/0.11 Specific volume electrical resistance, Ohm⋅cm At least 10 ¹⁴ 1.25⋅10 ¹⁶ 6.62⋅10 ¹⁶ 1.16⋅10 ¹⁷ 1.10⋅10 ¹⁷ 1.16⋅10 ¹⁷ 6.92⋅10 ¹⁶ 9.85⋅10 ¹⁶ Taber wear resistance (CS-17 wheel), mg/1000 cycles no more than 80 18 18 18 18 18 18 18 Tensile yield strength at +23 °C, MPa At least 18 18.2 18.2 18.3 18.2 18.2 18.3 18.2 Tensile strength at +23 °С/+60 °С, MPa At least 18/at least 15 23.7/15.6 23.5/15.4 23.5/15.4 23.3/15.4 23.4/15.6 23.3/15.4 23.6/15.5 Elongation at break at +23 °С/-45 °С, % Not less than 400/ not less than 100 890/205 872/195 873/195 870/194 872/195 868/196 882/201 Elongation at break at +23°C after thermal aging (100 days at +120°C), % At least 400 656 638 635 635 640 641 648 Change in elongation at break at +23°C after thermal aging (1000 hours at +110°C), % no more than 20 17.21 17.44 16.98 17.22 17.07 17.28 16.72 Reduction in elongation at break at +23°C after exposure in an artificial light weather chamber (500 hours at a radiation intensity of 120 W/ ^m2 ), % No more than 30 5.61 5.52 4.88 5.26 5.32 5.57 4.22 Oxidation induction period at +200 °С and oxygen flow 100 ml/min, min At least 80 212 211 208 210 210 212 209 Change in initial FEC after 500 h of aging in air at +120°C, % No more than 50 36.48 37.03 36.72 36.51 37.14 36.54 35.91 Change in the initial PIO after 30 days of soaking in water at +95 °C, % No more than 50 28.11 28.04 27.79 28.04 27.53 28.01 26.97 Stress cracking resistance at +50 °С, h At least 5000 Resp. Resp. Resp. Resp. Resp. Resp. Resp. Coating impact strength at +60 °С/-45 °С, J/mm At least 6/ at least 10 More than 6/ More than 10 More than 6/ More than 10 More than 6/ More than 10 More than 6/ More than 10 More than 6/ More than 10 More than 6/ More than 10 More than 6/ More than 10 Coating adhesion at +23 °С/+80 °С, N/cm Not less than 250/ not less than 100 298/192 312/190 264/184 280/190 256/167 263/207 276/185 Coating adhesion at +23°С after soaking in water (1000 h at 95°С), N/cm At least 100 186 180 195 175 196 187 194 Decreased coating adhesion at +23°C after soaking in water (1000 h at 80°C), % No more than 50 22.82 8.65 12.12 36.43 11.33 16.35 19.57 Coating resistance to thermal cycling from -60 °С to +20 °С At least 10 cycles Resp. Resp. Resp. Resp. Resp. Resp. Resp. Initial contact resistance of the coating in 3% NaCl aqueous solution at +23 °C, Ohm m ² At least 10 ¹⁰ 4.6⋅10 ¹⁰ 5.0⋅10 ¹⁰ 4.8⋅10 ¹⁰ 1.9⋅10 ¹⁰ 7.8⋅10 ¹⁰ 6.53⋅10 ¹⁰ 5.6⋅10 ¹⁰ Peeling area of the coating at cathodic polarization after exposure for 30 days at +60 °С/ +80 °С, cm ² No more than 10/ no more than 15 2.9/8.0 3.0/9.0 3.7/13.3 1.9/11.3 2.8/9.3 3.7/11.1 2.2/10.5 Coefficient of sliding friction on ice Not more than 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03

Claims (12)

A method for producing a powder polyethylene composition for protection against icing and corrosion of ship hulls and steel pipelines, including preliminary preparation of the composition in granular form by mixing in the melt and granulating the following raw materials in the specified ratio, wt. %: bimodal high-density polyethylene with a melt flow index of 0.28-0.32 g/10 min at a temperature of 190°C and a load of 2.16 kgf - 16.9; cast high-density polyethylene with a melt flow rate of 28.0-32.0 g/10 min at a temperature of 190°C and a load of 2.16 kgf - 59.5-9.9; maleized cast high-density polyethylene with a melt flow rate of 16.0-20.0 g / 10 min at a temperature of 190 ° C and a load of 2.16 kgf and 0.9-1.1 wt.% of grafted maleic groups - 4.8- 5.2; ethylene-octene copolymer with a melt flow index of 4.0-6.0 g/10 min at a temperature of 190°C and a load of 2.16 kgf, a hardness of 68-72 Shore A and a melting point of 55-60°C - 4.9- 5.1; block copolymer "styrene-ethylene-butylene-styrene" (SEBS) with a styrene content of 31-34 wt.% and a viscosity in a solution of toluene (10 wt.%) at 25 ° C - 2000-6000 MPa s - 9.9 -10.1; dye superconcentrate based on cast linear polyethylene, having a melt flow rate of 48.0-52.0 g/10 min at a temperature of 190°C and a load of 2.16 kgf - 1.5-2.0; primary antioxidant of the phenolic type, which is tetrakismethylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate) - 0.3-0.4; secondary phosphite antioxidant, which is tris-(2,4-di-tert-butylphenyl)phosphite - 0.6-0.8; light stabilizer poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidinyl )imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]] - 0.4-0.6; a fluoropolymer having a melt flow index of 6.0-14.0 g/10 min at a temperature of 265°C and a load of 5.0 kgf and a melting point of 110-126°C - 0.1; and subsequent mechanical grinding to an average particle size of 150-250 microns.

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