Chemically stable coating composition

FIELD: paint-and-varnish industry.

SUBSTANCE: invention relates to chemically stable coating compositions destined to protect, in a multilayer manner, equipment, metallic structures as well as concrete and reinforced concrete units operation under in-door and out-of-door conditions against action of corrosive chemical production gases and vapors and against prolonged action of spilled concentrated acids and alkali solutions, prolonged action of salt solutions at temperature not higher than 60°C. Composition contains varnish based on perchlorovinyl resins as principal film forming substance, pigments: titanium dioxide and/or graphite, filler: microtalc, sodium nitrite as corrosion inhibitor, organic solvent, and additional film-forming substance: mixture of chlorinated C₁₂-C₃₀-paraffins having general formula: C_nH_2n+2-xCl_x (n=12-30 and x=18-23), containing at least 70 wt % chlorine, in amount 5.52-28 wt %.

EFFECT: enhanced chemical stability and adhesion of coatings.

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The invention relates to a paint and varnish materials, namely, chemically resistant compositions intended for the protection in multilayer coating equipment, metal structures and concrete and reinforced concrete building structures, used indoors and outdoors, from the effects of corrosive gases and vapors chemical industries, prolonged exposure to concentrated acids, alkali solutions in the Straits, from prolonged exposure to salt solution at a temperature not exceeding 60 plus°C.

Currently, the paint industry produces a wide range of materials to protect the equipment of chemical productions. The most resistant coating to the action of solutions of acids and salts get when using paints and varnishes based on chlorine-containing polymers - advanced chlorinated polyvinyl chloride, copolymers of vinyl chloride with vinylidenechloride and phenol Tihomirov. In alkaline solutions the greatest resistance are coatings based on epoxy oligomers, chlorinated rubber and a copolymer of vinylidenechloride with vinyl chloride.

Known perchlorovinyl paint compositions for protective coatings, characterized by low permeability, high water and weather resistance. They are resistant to the action is s solutions of mineral acids, alkalis and salts, and aggressive gaseous products (especially if they contain chemically resistant modifiers, plasticizers and pigments). Perchlorovinyl coatings withstand the action of water, fats, oils, alcohols, aliphatic hydrocarbons (gasoline, white spirit and other). They are not exposed to mildew and is resistant to fire, almost are nonflammable [Livshits, M., Przyjalkowski B. I. Paints. The Handbook. M, Chemistry, 1982, s].

The disadvantages of perchlorovinyl coatings include: lack luster and the propensity for contamination and softening at temperatures above 60°With; low adhesion to metal surfaces; low thermo - and light-fastness, long curing at ambient conditions, a sharp decrease in adhesion when exposed to the coating aggressive environments [Livshits, M., Przyjalkowski B. I. Paints. The Handbook. M, Chemistry, 1982, s].

Part of perchlorovinyl varnishes, enamels, primers and coatings are film-forming resin PSC-PP and PSC-NL entered into a 10-25%solutions, modifiers, plasticizers, pigments and various additives [Livshits, M., Przyjalkowski B. I. Paints. The Handbook. M, Chemistry, 1982, s].

To increase gloss, adhesion, the content of non-volatile substances and to reduce thermoplasticity coverage in the W ill result modifiers. The content of the modifier ranges from 0.15 to 0.5 mass. PM 1 mass. including perchlorovinyl resin. As modifiers apply drying alkyd resin (N 135, PF-077, FL-390 and others), less alkidnoakrilovye resin AC-4.

Plasticizers increase the flexibility of the coating and reduce their permeability. They enter in the quantity of 0.3-0.5 wt. PM 1 mass. including perchlorovinyl resin. The most commonly used tricresylphosphate, dibutyl phthalate, chloroparaffin CP-470, sovol (polychlorvenil) [Livshits, M., Przyjalkowski B. I. Paints. The Handbook. M, Chemistry, 1982, s-191].

The closest to the invention is enamel XB-785 containing moderately viscid perchlorovinyl resin, plasticizer, modifier, pigment, organic solvents [Enamel XB-785 and varnish XB-784. GOST 7313-752. Technical specifications].

The coating on the basis of this enamel has insufficient resistance to concentrated acids, salts, alkalis and weak adhesion to the metal surface.

An object of the invention is to improve chemical resistance and increase adhesion of the coating.

The technical result is achieved due to the fact that chemically resistant composition for coating comprising lacquer XB-784-based perchlorovinyl resin, pigment, filler - micro-talc and organic solvent, characterized in that it contains is the quality of the additional film-forming chloroparaffin CP-T - the mixture chlorinated paraffins with a chain length₁₂-C₃₀with an average empirical formula

C_nH_2n+2-xCl_xwhere x=18-23.

n is the number of carbon atoms in the molecule paraffin,

n=12-30,

containing not less than 70 wt.% chlorine, as pigments - titanium dioxide and/or graphite, and may contain a corrosion inhibitor in the following ratio of components (wt.%):

Use as additional film-forming substance is a mixture of chlorinated paraffins with carbon chain length of C₁₂-C₃₀and mass fraction of chlorine of not less than 70 wt.% (solid chloroparaffin) 5,52-28 wt.% leads to a significant improvement in chemical resistance and coating adhesion, reduced Flammability.

In the proposed chemical-resistant composition is used lacquer XB-784, which is a solution of chlorinated irrigation is nilhloridnyj resin in a mixture of volatile organic solvents with addition of a plasticizer [Enamel XB-785 and varnish XB-784. GOST 7313-75. Technical specifications].

As the plasticizer used conventional chemicals used as plasticizers, paint materials, such as tricresylphosphate, dibutyl phthalate, sovol, chloroparaffin CP-470, dioctylphthalate and other

As the organic solvent is toluene, xylene, butyl acetate. acetone, P-4, P-5 and other

As the micro-talc, as a rule, use the micro-talc content of water soluble salts is not more than 0.1 wt.% and the residue insoluble in hydrochloric acid is not less than 90 wt.%.

As the corrosion inhibitor is sodium nitrite.

Table 1 presents the dependence of the chemical resistance of the composition to cover I to the static action of 35%hydrochloric acid, an aqueous solution of sodium hypochlorite and water from a number of chloroparaffin.

Table 2 presents the dependence of the chemical resistance of the composition for coating II to the static action of 98%sulfuric acid, 46%aqueous sodium hydroxide solution and water from the number of chloroparaffin.

Tests were conducted on metal samples. The composition was applied in 6 layers with a brush. The thickness of layer 1 of the dry coating was 50-60 microns. Before testing the prepared samples was kept at a temperature of (20±2)°C and relative humidity (65±5)% for at least 10 days is K.

The tests were carried out in accordance with GOST 9.403-80, method a, using several parallel samples. During the tests was controlled to change the appearance.

In tables 1 and 2 indicate the time during which the appearance of the coatings remained unchanged.

From table 1 it is evident that the presence of solid chloroparaffin as additional film-forming substance increases chemical resistance of the coating, however, increasing the number of solid chloroparaffin reduced hardness.

From tables 1 and 2 shows that the best result of the tests on the resistance of the film to static action of 35%hydrochloric acid, aqueous sodium hypochlorite solution with a mass concentration of active chlorine 170-190 g/DM³, 46%sodium hydroxide solution, 98%sulfuric acid is achieved when the concentration of solid chloroparaffin - 10-15 wt.%.

In the proposed chemical-resistant composition for coating the main opaque pigments are titanium dioxide and/or graphite. Titanium dioxide has a high hiding power, but not enough racks concentrated in aggressive environments, therefore, the use of titanium dioxide in a concentration of more than 5 wt.% removes chemical resistance of the coating.

Graphite has good hiding power, resistant to acids. alkalis and aggressive gases, but education is the duty to regulate heavy sediment loads. Coatings made from the same graphite, less chemically resistant than coatings made with the use of micro-talc and graphite, so the use of graphite in a concentration of more than 5 wt.% it is impractical.

The micro-talc is a filler with a low hiding power and coloring power, so along with them, you need to use titanium dioxide and/or graphite to impart opacity chemically resistant composition for coating.

Sodium nitrite increases chemical resistance in highly corrosive environments, however, reduces the resistance of the coating, therefore, the use of sodium nitrite in a concentration of more than 0.5 wt.% it is impractical. Sodium nitrite is not used in compositions intended to protect equipment from exposure to aqueous solutions of salts, chemically contaminated wastewater in the sewers.

Resistance to static action of aggressive media increases with the number of layers. The best result is achieved when the coating thickness of 500 microns.

Chemically resistant composition for coating is prepared based on the following technologies:

1. Preparation of solution of solid chloroparaffin in an organic solvent

Preparation of solution of solid chloroparaffin in an organic solvent is made by dissolving under stirring those which begins 1 hour.

2. Preparation of chemically resistant composition for coating

Preparation of pigment paste is made by mixing the solution of chloroparaffin with varnish XB-784 and dry components of the composition (micro-talc, titanium dioxide and/or graphite, sodium nitrite), followed by stirring for at least 1 hour and dispersing the mixture on a bead mill to achieve the degree of milling is not more than 30 μm.

Below is the recipe, explaining the essence of the invention, but not limiting its scope.

Example 1

The most resistant to static action of 35%hydrochloric acid, aqueous sodium hypochlorite solution with a mass concentration of active chlorine 170-190 g/DM³is the composition I received the following ratio of components (wt.%):

The quality of composition I are shown in table 3.

Example 2

Resistant to static action of 35%hydrochloric acid aqueous solution hypochlo the ITA sodium with a mass concentration of active chlorine 170-190 g/DM ³is the composition Ia obtained in the following ratio of components (wt.%):

The quality of composition Ia are shown in table 3.

Example 3

The most resistant to static action of 98%sulfuric acid and 46%aqueous sodium hydroxide solution is composition II obtained in the following ratio of components (wt.%):

The quality of composition II are shown in table 3.

Table 4 presents the test results of the coatings of the proposed compositions and enamel XB-785 resistance to static action of aggressive media.

Tests were conducted on m is a metallic samples. The composition was applied in 6 layers with a brush. The thickness of layer 1 of the dry coating was 50-60 microns. Before testing the prepared samples was kept at a temperature of (20+2)°C and relative humidity (65+5)% for at least 10 days.

The tests were carried out in accordance with GOST 9.403-80, method A. In the tests was controlled to change the appearance.

Note. In table 4 the abbreviation "b/and" means "unchanged".

Method of use

Chemically resistant composition is thoroughly mixed, diluted if necessary with a solvent.

The surface is cleaned from dust, dirt, loosely adhering rust, peeling paint chips, washed with solvent, wipe with a soft cotton cloth, do not leave on the surface of the fibers are dried. Chemically resistant composition is applied to the surface by brush, roller, loading, hydraulic spraying at low pressure without the need for priming in three or six layers, depending on operating conditions, with layer-by-layer drying for 30-60 minutes at a temperature not below 0°C.

The consumption of chemically resistant composition for single-layer coating 120-200 g/m²depending on application methods and structure of the surface.

Chemically resistant composition for coating comprising lacquer XB-784-based perchlorovinyl resin, pigment, filler - micro-talc and organic solvent, characterized in that it contains as additional film-forming chloroparaffin CP-T is a mixture of chlorinated paraffins with a chain length₁₂-C_{30 with an average empirical formula}

_{WithnH2n+2-xClxwhere x=18-23,}

where n is the number of carbon atoms in the molecule paraffin;

n - 12-30,

containing not less than 70 wt.% chlorine, as pigments - titanium dioxide and/or graphite, and may contain a corrosion inhibitor is sodium nitrite in the following ratio, wt.%: