RU2428443C1 - Complex anti-corrosion polyurea-urethane coating - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: anti-corrosion protective coating consists of the first element - a single-component moisture-hardened isocyanate primer, which contains at least 75 wt % of a nonvolatile residue and 6…8 wt % of isocyanate groups. The second element is a thick-layer external coating, to produce which a double-component polyurea-urethane mastic is used, containing an isocyanate prepolymer on the basis of diphenyl methane diisocyanate with mass portion of NCO-groups making 15…17% and dynamic viscosity at the temperature of (20±3)°C - 3…10 Pa·s, and the component it hardens with active atoms of hydrogen with hydroxyl number making 95…105 mgKOH/g, mass portion of total titrated nitrogen of 4.2…4.5%, containing a mixture of simple or complex polyester diol with molecular weight of 800…1000 c.u., sterically hindered diamine with amine number of 12…16.7%, oxypropylated ethylene diamine with hydroxyl number of 640…800 mgKOH/g and liposoluble organic pigments, at the ratio of isocyanate prepolymer to a component with active atoms of hydrogen, which ensures hardening of a thick-layer external coating until the required level of operational characteristics is produced.

EFFECT: coating ensures high level of adhesion, resistance to cathode lamination with preservation of the main physical-mechanical indices and ecological safety in process of insulation works.

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Description

The present invention relates to integrated anti-corrosion coating systems, including a protective primer layer and an external polymer coating of the barrier type, intended, in particular, to protect metal pipes, shaped fittings, fittings, valves and mounting units of underground gas and oil pipelines against corrosion and underwater (with deepening in the bottom) gaskets, pipelines and fittings of compressor and pump stations, underground gas storage stations and oil storage facilities with a range of tempo Operational temperature is from minus 30 ° С to plus 60 ° С in the conditions of factory (base) or route application during their construction, reconstruction and overhaul.

Complex anti-corrosion coatings include two components:

- a thin-layer primer film obtained on the basis of a primer that protects the metal surface from the effects of an aggressive environment and provides reliable adhesion between the metal and the outer thick-layer polymer coating;

- a thick-layer outer polymer coating of the barrier type, protecting the primer film from mechanical damage associated, in particular, with the movement of the soil, with the influence of groundwater, temperature extremes and determining, ultimately, the general protective anticorrosion properties.

Thus, the operational reliability of complex anti-corrosion coatings depends on the totality of the properties of the primer-external polymer coating system.

According to the requirements of GOST R 51164-98 "Steel trunk pipelines. General requirements for corrosion protection" and "Technical requirements of Gazprom" for external coatings based on thermosetting materials for corrosion protection of pipes, fittings, valves and mounting units of pipelines with temperature operation from minus 20 ° С to plus 100 ° С "(dated August 2, 2005) from 14 regulated quality indicators of external protective coatings of gas and oil pipelines with the most important indicators determining The long-term protective properties of complex coatings operating in corrosive environments when exposed to electric potential are:

- the value of the initial adhesion of the coating to the metal and a decrease in its level after holding metal samples coated in water for 1000 hours at a temperature of (60 ± 3) ° С;

- the resistance of the coating to cathodic peeling, determined after exposure of the samples in a 3% sodium chloride solution at a polarization potential of 1.5 V at a temperature of (20 ± 3) ° C for 30 days;

- the level of physico-mechanical characteristics of the polymer coating (impact strength, potential, penetration and elongation at break).

Other quality indicators, as a rule, do not undergo significant changes during the operation of pipelines.

The first two significant indicators (adhesion and cathodic peeling) are determined by the quality of the primer layer, and the physical and mechanical characteristics are determined by the quality of the thick-layer polymer coating of the barrier type.

Thus, the selection of the optimal combination of primer and components of a thick polymer coating is a complex technical problem that can only be solved on the basis of numerous and lengthy tests.

In addition, the rheological properties and kinetics (speed) of curing both elements of the anti-corrosion coating system, especially the outer layer, should provide the possibility of their application by progressive mechanical methods.

A comprehensive anticorrosion coating is known, developed in Japan (KAWAKAMI Paint Co., Ltd.), satisfying these requirements and consisting of an epoxyisocyanate primer (UP-1000 primer), the composition of which includes a polyisocyanate hardener and epoxy polyol obtained by reacting it epoxy resin with a low molecular weight diol in an organic solvent medium with the addition of a number of technological and functional additives, with a ratio of hardener to epoxy polyol, I provide an excess of hydroxyl (OH) groups: a molar ratio of NCO / OH = 0.6 ... 0.9, and an outer polyurea thick-layer coating (mastic "FRUCS-1000A") containing an isocyanate prepolymer hardener (a product of the interaction of polyisocyanate with diol) and a curable a component with active hydrogen atoms - a mixture of polyoxyalkylene polyol or polyoxyalkyleneamine with a hydroxyl (OH-) and / or amine (NH ₂ -) number not exceeding 170 mgKOH / g, aromatic spatially hindered polyamines and coal tar, taken in an amount of 2.5 ... 50 , 0 parts by weight per 100 parts by weight composition. This composition also includes up to ten different functional and technological additives (1).

Primer "UP-1000" is applied by conventional methods of air and airless spraying. Mastic "FRUCS-1000A" is applied only by the method of "hot" airless spraying by high-pressure apparatuses with separate supply of components with mixing directly in the spray gun, since the pot life of the mixture of components does not exceed 5 seconds.

The disadvantages of the above complex polyureaurethane coating are: complexity (multicomponent) in the composition of both the primer composition and the thick-forming mastic (both are two-pack systems); short pot life of the thick-forming mastic after mixing the components, which limits the choice of the type of spray gun. In addition, coal oil used in the composition of thick-forming mastic has carcinogenic properties in relation to the human body and is environmentally hazardous.

Closest to the claimed technical essence and component composition of the coating elements is the domestic complex anti-corrosion polyurea-urethane coating ("BIURS"), consisting of a two-pack epoxy primer ("Primer-MB"), including component A - a solution of modified epoxy resin and component B - amine hardener, and two-pack polyureaurethane mastic ("BIUR") as a thick-forming outer coating, including an isocyanate prepolymer (prepolymer) hardener with the content of isocyanate (NCO-) groups of 13 ... 14% and the component that it cures with active hydrogen atoms contained in the hydroxyl (OH-) and amino groups (NH ₂ -; -NH-) of epoxy polyols and polyamines dissolved in the middle fraction of coal or shale resin with a viscosity of 18 ... 25 cSt and a basicity of 1.3 ... 1.5 mg · equiv / g HCl (2).

"Primer-MB" is applied by conventional methods of air or airless spraying. BIUR mastic, like FRUCS-1000A mastic, is applied only by the method of "hot" airless spraying with high-pressure apparatuses with separate supply of components (base and hardener) with mixing directly in the spray gun, since the life time of the mixture of components at temperature application (50 ... 70 ° C) does not exceed 10 seconds.

The prototype coating, like the previous similar coating, satisfies the requirements of OAO Gazprom and OAO AK Transneft in terms of a set of characteristics. However, it is multicomponent in the composition of both the primer composition and the thick-forming mastic (both two-pack systems). In addition, the short life time of the BIUR mastic limits the choice of the type of spray device, and the coal or shale oil included in the basis of this mastic has carcinogenic properties and is environmentally harmful. The disadvantages of the coating of the prototype include a rather large amount of drop in adhesion, after its long-term exposure to hot water.

The technical problem solved in the framework of the present invention is the creation of a comprehensive anti-corrosion polymer coating that meets the requirements for external protective coatings of gas and oil pipelines, with a simplified component composition of the coating elements, eliminating carcinogenic coal and shale oils from their compositions, increasing the pot life thick-forming mastic, and with increased adhesion and resistance to cathodic peeling with long-term maintaining basic physical and mechanical characteristics and other protective properties.

The solution to the above goal is achieved due to the fact that, in contrast to the well-known anticorrosive polymer coating-prototype, which consists of two elements: a thin layer of primer, obtained on the basis of a two-pack epoxy primer, and a thick outer protective coating, obtained on the basis of two-component polyurea mastic, proposed complex polyureaurethane coating as a primer layer contains a coating obtained on the basis of a one-component moisture of an isocyanate primer containing at least 75% (by weight) dry residue and with a mass fraction of isocyanate (NCO-) groups of 6 ... 8%, and to obtain an outer thick-layer coating element, a two-component polyureaurethane mastic including an isocyanate prepolymer based on diphenylmethane diisocyanate is used the proportion of NCO groups - 15 ... 17% and a viscosity of 3 ... 10 Pa · s at (20 ± 3) ° С and the mixture composition which he cures with active hydrogen atoms with a hydroxyl number of 95 ... 105 mgKOH / g, mass fraction of total titrated nitrogen 4 , 2 ... 4.5%, including eating ingredients in their mass ratio (wt.%):

- simple or complex polyetherdiol with molecular weighing 800 ... 1000 cu -55 ... 60 - spatially hindered diamine with an amine number of 12 ... 16.7% -35 ... 40 - N, N, N ', N'-hydroxypropylated ethylenediamine with hydroxyl number 640 ... 800 mgKOH / g - 3 ... 4 - organo (fat) soluble pigments - the rest is up to 100

when the ratio of isocyanate prepolymer: composition with active hydrogen atoms, providing the curing of a thick coating to obtain the desired level of physico-mechanical characteristics and long-term protective properties.

The recommended thickness of the primer is 40 ... 80 microns (dry) and 2 ... 4 mm for a thick coating element. The drying time between the coating elements is 3 ... 12 hours at a temperature of (20 ± 3) ° С.

The primer is a moisture-curing coating applied by conventional methods of air or airless spraying using commonly available spray guns, as well as with a roller or brush. Two-pack polyureaurethane mastic with a 100% dry residue is applied by the method of "hot" (temperature of the components 50 ... 70 ° C) airless spraying with separate feeding of the components with their mixing either directly in the spray gun of the "FUSION" system, or in a static mixer with a length of hose 1.5 ... 3 m from it to a sprayer device that is simpler in design, since the formulation of the proposed polyureaurethane mastic provides a pot life after mixing the components at a temperature of 50 ... 70 ° C - 60 ... 120 seconds, as opposed to the 5 ... 10 second vitality of known mastic coatings. As apparatuses for airless spraying, 2-K high-pressure apparatuses of the WIWA firm (Germany) or GRACO (USA) are used.

The recommended molar ratio between the components of the mastic (isocyanate prepolymer: composition with active hydrogen atoms) 1.1 ... 1.3 / 1.0 NCO / COH + NH ₂ ) depending on the required rigidity of the complex coating, which determines the mass ratio between the components as 1 , 2 ... 1.4 / 1.0.

As a polyetherdiol with a molecular weight of 800 ... 1000 cu I use either polyethylene glycol adipate of the PDA-800 brand (TU 38.103287-80), or polyoxypropylene glycol of the Laprol-1052 brand (TU 2226-411-05761784-95) or their imported analogues.

The following diamines can be used as spatially hindered diamines:

Table 1 Name Gross formula Molecular weight Amine number,% 1,3,5-triisopropyl-2,4-diaminobenzene C ₁₅ H ₂₆ N ₂ 234 12.0 Triethyl diaminobenzene C ₁₂ H ₂₀ N ₂ 192 16.7 3,3'-dichloro-4,4 'diamino-diphenylmethane C ₁₃ H ₁₂ N ₂ Cl ₂ 267 12.0 4,4 'diaminodiphenylmethane C ₁₃ H ₁₄ N ₂ 208 13.5

As hydroxypropylated ethylenediamine with a hydroxyl number of 640 ... 800 mgKOH / g, aminotetrols of the brands "Voranol-640", "Voranol-800" (import) or the domestic analogue "Lapromol-294" are used.

Of the fat-soluble pigments, in particular, the following organic dyes can be used:

- organic fat-soluble dark red dye "Zh" (TU 6-14-37-80);

- fat-soluble green dye "Color Index: Solvent Green 3" (import);

- fat-soluble blue dye "Color Index: Solvent Green 36" (import);

- Dye, fat-soluble 9315 black "Iprozin") (import).

The above limits of the ratios between the components of the composition with active hydrogen atoms are determined experimentally and are optimal from the point of view of achieving a positive technical effect, compliance with the requirements of Gazprom and TK Transneft and the minimum cost.

The composition with active hydrogen atoms is made on standard capacitive chemical equipment by mixing all the components at a temperature of 80 ... 110 ° C until a homogeneous solution is obtained.

As an isocyanate prepolymer based on diphenylmethanediisocyanate, which is a hardener of a mastic component with active hydrogen atoms, industrially produced ferro-polymers with a mass fraction of NCO-groups of 15 ... 17% and dynamic viscosity at (20 ± 3) ° C 3 ... 10 Pa · s are used, for example prepolymer "Forpol-NCO" (TU 2458-104-20504464-2006). Moreover, its density lies within 1135 ... 1145 kg / m ³ .

As a one-pack moisture-curing primer, industrially produced primers (primers) with a mass fraction of solids of at least 75% and with a mass fraction of NCO groups of 6 ... 8%, for example, Forpol-Primer primer (TU 2458-114-20504464-2009), are also used. ), primer UR-0446 "Urethane-Anticor" (TU 2313-025-20802364-2005), primer "STEELPAINT-RU-MICA" (import). Moreover, their density and viscosity at (20 ± 3) ° C are respectively 1250 ... 1380 kg / m ³ and 450 ... 550 MPa · s.

Comparison of the proposed complex anticorrosive polyureaurethane coating with known similar coatings allows us to conclude that it meets the “Novelty” criterion, since this case contains a new set of coating elements (one-pack moisture-curing isocyanate primer + two-pack thickness-forming polyurea-urea mastic), isocyanate-based prepolymer mastic is used the content of NCO-groups (15 ... 17% instead of 13 ... 14%) and a new set of ingre Dentin composition with active hydrogen atoms.

The combination of the above innovations led to a new effect - to obtain an anti-corrosion protective coating with increased resistance to cathodic peeling, with higher adhesion to the metal substrate and to its long-term maintenance of a high level. In addition, the range of applied ingredients of polyureaurethane mastic did not allow us to clearly predict the increase in the viability of the mastic by almost an order of magnitude after mixing its components, while maintaining the thixotropy of the mass after its application to both horizontal and vertical metal products. The above indicates that the proposed technical solution meets the criterion of "Inventive step".

The proposed formulations of the coating elements necessary to obtain a comprehensive anti-corrosion protective coating are focused on the use of ingredients of both domestic and foreign production, manufactured on an industrial scale, using standard chemical equipment to produce them. All the constituent elements of the coating are applied to the protected metal surfaces using the existing methods of machine application or manually (primer). This allows you to make a reasonable conclusion about the conformity of the proposed technical solution to the criterion of "Industrial applicability".

Coating samples for testing on metal plates made of steel grade St.3 with a size of 150 × 150 × 6 mm were prepared as follows: the primer was applied by air spraying to obtain a dry layer with a thickness of 40 ... 80 μm, followed by drying at a temperature of (20 ± 3) ° С within 5 ... 6 hours;

- a thick-forming mastic was applied onto the primed surface using a WIWA airless high-pressure apparatus of the DUOMIX-230 brand with a thickness of 2.5 ... 3.1 mm, while the temperature of the mastic components was 50 ... 70 ° C.

A free film of thick-forming mastic for conducting physical and mechanical tensile tests was obtained by spraying the mastic onto a fluoroplastic plate.

Tests were carried out 5 days after coating. All tests were carried out in accordance with the methods of GOST R 51164-98.

The technical essence and advantages of the proposed integrated anti-corrosion polyurea coating are illustrated by the following experimental data.

EXAMPLES

Table 2 shows the formulation of the elements of the coating of the prototype and the proposed integrated coating, and table 3 shows the results of their tests.

Thus, as can be seen from the above data, the claimed complex anticorrosive polyurea coating, due to the simplification of the component composition, the combination of new elements and the use of new ingredients in their formulations, made it possible to provide a higher resistance of the protective polymer coating to cathodic peeling, a higher level of adhesion and its delayed reduction in time while maintaining a high level of physical and mechanical properties and operational characteristics. In addition, the thickening mastic for the outer coating has an increased time for maintaining the viability of the reaction mixture, which simplifies the hardware design of the technological process of applying a protective polymer coating to gas and oil pipelines and their corresponding component parts. And the absence of carcinogenic coal and shale oils in the coating elements ensures the environmental cleanliness of the insulation work.

Information sources.

1. RF patent No. 2072905. IPC ⁶ C09D 175/02. Claim 09/04/1992, application no. 5052945/04; publ. 02/10/1997.

2. RF patent No. 2216561. IPC ⁷ C09D 5/08; C09D 175/04. Claim March 4, 2002, application no. 2002106194/04; publ. 11/20/2003 - prototype).

Claims (1)

Integrated anticorrosive polyureaurethane coating for steel surfaces, designed to protect metal pipes, shaped fittings, valves and mounting assemblies of gas and oil pipelines of underground and underwater laying, pipelines and valves of compressor and pump stations, underground gas storage stations and oil storage tanks from corrosion operating temperature range from minus 30 to plus 60 ° С in the conditions of factory, basic or route application during their construction, river structure and overhaul, consisting of two elements: a thin-layer primer coating and a two-component thick-forming external polyurea-urethane coating, including an isocyanate prepolymer based on diphenylmethanediisocyanate and a component that cures with active hydrogen atoms of hydroxyl and amino groups, characterized in that they are thin-coded isocyanate primer containing not less than 75 wt.% solids and 6 ... 8 wt.% zocyanate groups, and to obtain an outer thick-forming layer, a two-component polyureaurethane mastic is used, including an isocyanate prepolymer with a mass fraction of isocyanate groups of 15 ... 17% and dynamic viscosity at a temperature of (20 ± 3) ° C 3 ... 10 Pa · s, and the composition cured by it with active hydrogen atoms with a hydroxyl number of 95 ... 105 mgKOH / g, mass fraction of total titratable nitrogen of 4.2 ... 4.5%, containing the following ingredients in their ratio, wt.%:
simple or complex polyetherdiol with a molecular weight of 800 ... 1000 cu 55 ... 60 spatially hindered diamine with an amine number of 12 ... 16.7% 35 ... 40 N, N, N ', N'-hydroxypropylated ethylenediamine with a hydroxyl number of 640 ... 800 mgKOH / g 3 ... 4 fat soluble organic pigments the rest is up to 100
when the ratio of isocyanate prepolymer: component with active hydrogen atoms, providing curing of a thick outer coating to obtain the desired level of performance.