RU2225422C2 - Two-component composition for outside protection coating for steel surfaces - Google Patents

Abstract

FIELD: protection coatings. SUBSTANCE: invention relates to protection of steel products, in particular to automatically sprayed coatings applied onto prime layer and intended for protecting tubes, stop equipment, various-type containers operated both in underground and open-air conditions. Composition contains adduct with active hydrogen atoms obtained by reaction of epoxide oligomer or epoxide oligomer mixture with epoxide number 3.1-3.9 mg-equ/g, mixture of aromatic amines with amine number 9.0-10.4 mg-equ/g, and middle fraction of coal or shale resin with viscosity 18-25 cSt and basicity 1.3-1.5 mg-equ/g HCl. Solidification of adduct is accomplished with the aid of any polyurethane oligomer with 12-14% HCO groups. Impact strength of coating within temperature range from -40 C to +40 C is 15-24 J, adhesion after 1000 h holding in water at 50 C is at least 4 MPa, swelling in water at 80 C is 1.3-4%, vitality time 3-12 sec, resistance to cathode peeling after 3-day ageing at 60 C in NaCl solution is 4.5-9.5 sq.cm. EFFECT: optimized chemical analysis of coating composition. 5 cl, 3 tbl, 10 ex

Description

 The invention relates to the field of protection of steel products from corrosion, namely, machine-sprayed coatings applied to the primer layer and designed to protect steel products, in particular pipes, valves, various containers, operating both in underground operation and in the open air .

 A whole set of requirements is imposed on protective coatings, among which one of the main ones is the high insulating ability of the coating, characterized by a low cathodic peeling area with satisfactory physical and mechanical characteristics, as well as the low viscosity of uncured coating components, which makes it possible to spray machine.

A two-component composition of the outer coating (variation) is known that satisfies the specified requirements and contains component A - a polyurethane prepolymer hardener and component B - a mixture of liquid compounds, including a compound with active hydrogen atoms from the group of polyoxyalkylene polyols or polyoxyalkylene amines with a hydroxyl and / or amine number of not more than 170 mg KOH / g, chain extender - aromatic polyamine with an equivalent group ratio of NH ₂ / OH = 60: 40 ÷ 100/0, coal tar in an amount of from 2.5 to 50 wt. hours per 100 wt. including component B, which increases the anticorrosive effect and water resistance of the coating, various functional additives - wetting dispersant, antifoam, organometallic catalyst, as well as a stabilizer, dyes, fillers. A protective coating is formed after mixing components A and B using a spray device (US Pat. Russia 2072905, 05 D 7/22, publ. 10.02).

 However, this composition includes a large number of expensive additives.

 The invention solves the problem of simplifying and reducing the cost of the composition by expanding the raw material base of the components for the external protective coating with the exception of functional additives.

The essence of the invention lies in the fact that an adduct obtained by reacting an epoxy oligomer with an epoxy number of 3.1-3.9 mg eq / g or a mixture of epoxy oligomers with an epoxy number of mixture 3 is taken as a component interacting with a polyurethane hardener; 1-3.9 mg • equiv / g and a mixture of aromatic amines with an amine number of 9.0-10.4 mg • equiv / g and an average 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 in the following ratio, wt.%:
The specified epoxy oligomer or a mixture of epoxy oligomers - 27-44
The specified mixture of aromatic amines - 31.5-50.5 - The average fraction of coal or shale resin - 17.5-31.5
When these ingredients interact, an adduct with high homogeneity and active hydrogen atoms forms in the primary amino groups and the formed groups: hydroxyl and secondary amino groups.

 The resulting adduct reacts with a polyurethane hardener without a catalyst and other functional additives and provides the technological and operational characteristics of the composition that satisfy the requirements.

 For curing the composition, any polyurethane oligomer with isocyanate groups is used, which is suitable for machine spraying by its rheological properties and has a content of NCO groups of 12-14%.

 A distinctive feature is a component with active hydrogen atoms, which is not a mixture of polyoxyalkylene polyol, aromatic amine and coal tar, prone to delamination and requires stabilizing additives, but a uniform adduct obtained by the interaction of an epoxy oligomer, aromatic amines and shale or coal tar.

 All the ingredients of the composition are industrial and affordable products, and the absence of expensive additives reduces the cost of the composition without compromising the technological and operational properties.

 Example 1 to obtain a component with active hydrogen atoms (component 1).

In a vessel with a stirrer, 305 g of diaminodiphenylmethane and 40 g of aminotriethylbenzone are loaded with stirring, laproxide 703-436 g is added. The temperature is maintained in the range of 40-50 ^° C, 219 g of shale resin is introduced and stirred for an hour at a residual pressure of 20-30 mm, then the temperature is raised to 80 ^o and stirred for 3 hours. After cooling, the adduct is ready for use.

 Other compositions of component 1 are obtained in a similar manner, the composition of which is presented in table. 2.

Obtaining a cured composition and test samples
Plates 100x100 mm from steel st-3 are cleaned of rust by sandblasting, blown with compressed air, after which the soil is applied to the plates, obtained by mixing 100 g of the base primer B-EP-0237 (TU-2312-4780-05034239-97), 30 g acetone and 13 g of amine hardener AF-2 (TU-2494-511-00203521-94) to a homogeneous mass. The resulting soil is applied to the prepared plate with a brush or roller with a thickness of 80-100 microns and incubated for 6-8 hours.

 The adduct (component 1) is mixed with the hardener (component 2), the composition is applied to the plates to a thickness of 2.5-3 mm using an installation with separate airless feeding of the components.

 Urethane prepolymer "Freightur" according to TU 38.40.3871-99 or "Surel" -2 M according to TU 2294-002-46898377-01 is taken as a hardener. The volumetric ratio of adduct to prepolymer is 1.34: 1.

 After holding the coated plates for 10 days, the coating is tested for resistance to cathodic peeling. For other tests, the coating is applied to a polyethylene substrate without soil. The test results are presented in table.3.

As can be seen from the above data, the obtained coatings make it possible to obtain a high level of protection of the surface of steel pipes from the action of corrosion factors, as evidenced by the low value of the area of cathodic delamination - 4.5–9.5 cm ² after exposure at 60 ^° in a 3% NaCl solution for 30 days, high mechanical performance - impact strength of the coating from -40 ^o to +40 ^o C - 15-24 J.

The adhesion of the coating after 1000 hours of exposure in water at 50 ^o C - not less than 4 MPa.

Swelling in water at 80 ^o C - 1.3-4%.

 Potlife 3-12 sec.

 The examples given illustrate but do not limit the scope of the invention.

Claims (5)

1. A two-component composition for external protective coating of steel surfaces against corrosion, including an isocyanate hardener and a component cured by it with active hydrogen atoms of hydrosilic groups and amino groups, characterized in that it contains an adduct obtained by the interaction of at least an isocyanate hardener component by interaction , one epoxy oligomer with an epoxy number of 3.1-3.9 mg · equiv / g or a mixture of epoxy oligomers with an epoxy number of a mixture of 3.1-3.9 mg · equiv / g, a mixture of at least at least two aromatic amines with an amine number of the mixture 9.0-10.4 mg · equiv / g and an average 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, taken in the following ratio of these ingredients, wt.%: Epoxy oligomer or a mixture of epoxy oligomers with an epoxy number of 3.1-3.9 mg eq / g 27-44 A mixture of aromatic amines with an amine number of 9.0-10.4 mg equiv / g 31.5-50.5 The average 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 17.5-31.5 at a ratio of said adduct / isocyanate hardener sufficient to cure the adduct. 2. The two-component composition for external protective coating according to claim 1, characterized in that the epoxy oligomer with an epoxy number of 3.1-3.9 mg · eq / g or a mixture of epoxy oligomers with an epoxy number of a mixture of 3.1-3.9 mg · Eq / g are selected from the group consisting of epoxydian oligomers, polyoxypropylene epoxides, active epoxy diluents, polyoxychloropropylene epoxide. 3. A two-component composition for external protective coating according to claims 1 and 2, characterized in that it contains any combination of at least two as a mixture of aromatic amines with an amine number of the mixture 9.0-10.4 mg · equiv / g amines selected from the group consisting of aminobenzylaniline, diaminobenzene, 1,3,5-triisopropyl-2,4-diaminobenzene, triethylaminobenzene, triethyldiaminobenzene. 4. A two-component composition for external protective coating according to claims 1 to 3, characterized in that the isocyanate hardener contains 12-14% -NCO-groups. 5. The two-component composition for the outer coating according to claims 1 to 4, characterized in that the ratio of the adduct specified above to the isocyanate hardener is 1.22 ÷ 1.49: 1.

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