RU2378305C1 - Anticorrosion coating composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to anticorrosion zinc-containing coating compositions for corrosion protection of steel structures, objects and equipment used in average- and highly aggressive media and can be used in industrial and civil engineering, shipbuilding, motor car construction and bridge building for protecting engineering and hydraulic engineering structures, industrial and power installations, equipment of chemical and petrochemical industry, port structures. The anticorrosion composition contains finely dispersed zinc powder, zinc oxide, binder in form of chlorinated rubber, modified with alkyd resin with acidity of not more than 20 mgKOH/g and plasticised with chlorinated paraffin wax in a medium of organic solvent and target additives in form of polymerised amphoteric oil, organophilic bentonite and graphite.

EFFECT: obtaining one-pack anticorrosion composition with good processing characteristics with longer protection of coatings in average- and highly aggressive media.

4 tbl

Description

The invention relates to compositions of anticorrosive zinc-containing paints and varnishes for coatings such as soils, paints and enamels for tread corrosion protection of steel structures, products and equipment operating in medium and highly aggressive environments and can be used in industrial and civil engineering, shipbuilding, automotive and bridge construction for the protection of engineering and hydraulic structures, industrial and energy installations, equipment of chemical and petrochemical industry industry, port facilities.

Film-based zinc-containing formulations used for cold galvanizing a metal surface are widely known. It is also known that not all zinc-containing films on a film-forming basis provide protection of the metal surface by the tread mechanism, because the latter is provided, as a rule, provided that the zinc content in the dry coating is more than 90 wt.%. Moreover, an important condition for the tread protection mechanism is the preservation of the electrical conductivity of the coating. The global objective is to increase the duration of the protective properties of zinc-filled coatings, in order to approximate the duration of the protective effect of hot-dip galvanized coatings. This problem is solved by researchers by using mixed conductive pigments, the selection of powders and fillers with various particle shapes, the use of zinc alloy powders, as well as more active modifying additives to film-forming agents that form conductive complexes with pigments or fillers.

A wide range of zinc-containing compositions based on epoxy, urethane, polystyrene, ethyl silicate, etc., is known in science and technology. binders with a content of zinc powder in a dry coating of more than 90 wt.%. The applied zinc powder in all compositions, as a rule, meets the requirements of ISO 3549: 1995 (E). [A.S.Drinberg, E.F. Itsko, T.V. Kalinskaya. “Anticorrosion primers”, Publishing House of LLC “NIIPROINS LKM and P with OP”, St. Petersburg, 2006, p. 78-86]. The protective properties of zinc-filled coatings are due to the anodic dissolution of metallic zinc, in which only 25% of its mass content in the coating takes part, turning into oxide and (or) hydroxide. When filling the surface of the coating with these reaction products, the anodic dissolution of zinc ceases, and then protection is carried out according to the "barrier" mechanism of isolation from aggressive media.

In the known compositions, a binder is used as a film-forming base, which is individual polymers without special modification, which does not always allow to provide the required adhesion of the coating to the metal and the formation of conductive complexes with a filler. The resulting anti-corrosion compounds are made in the form of one or two packaging compositions.

Zinc-containing formulations based on a modified binder are also known. So, for example, a zinc-based paint based on a chlorine-containing binder is known - a modified thermoplastic polyvinyl chloride resin, where ED-20 or ED-41 diane resin is used as a modifier [RF Patent No. 1657518, IPC C09D 127/06; C09D 5/10; C09D 127/06; C09D 155: 02; C09D 163: 02, 1991].

Known paint is two-pack, while single-pack compositions are more technologically advanced in use. In addition, the known composition does not provide sedimentation stability when it is diluted to a working viscosity, and therefore, the coating is accompanied by unevenness in thickness and uneven distribution of zinc in the coating, which does not allow to provide a tread mechanism for protecting the metal surface.

Closest to the proposed is a single-pack primer containing, wt.%: Zinc powder highly dispersed 55-65; zinc oxide 10-15; a film former, consisting of a skinny alkyd varnish modified with a phenol-formaldehyde resin with an acid number of not more than 15 mg KOH / g 10-15; organophilic bentonite SD ₁ 0.3-0.8; lecithin 0.3-0.8; three-metal desiccant 0.1-0.3; toluene - the rest [RF Patent No. 2304602, IPC C09D 167/08; C09D 5/08; 2007]. As a fine zinc powder, any imported powder with an average particle size of 3-5 microns is used, for example, imported S3 brand (Norway) or EMP, UMP brand (South Korea) that meet the requirements of ISO 3549: 1995 (E).

The known composition is technologically advanced during application, and the resulting coating provides resistance to water and petroleum products. However, the use of an alkyd film former as a binder limits the aggressiveness of the environment in which the material can be used. Modification of the alkyd binder with a more chemically resistant phenol-formaldehyde resin made it possible to provide resistance to water and oil products, while a similar result is usually achieved when using higher quality epoxy and urethane binders. Known coating cannot be used in solutions of acids, alkalis, salts, organic acids, highly aggressive industrial and marine atmosphere. In addition, the known coating dries to degree 3 in 1.5-2.0 hours, which makes the coating process unreasonably long. Moreover, due to the high content of zinc oxide in the coating, it has weak protective properties.

The technical task of the present invention is the creation of a material that provides high technological properties of the process of anticorrosive surface treatment of products made of ferrous metals, while providing increased duration of tread protection in a medium and highly aggressive environment.

The problem is solved in that, in contrast to the known composition containing highly dispersed zinc powder in a binder medium, zinc oxide and target additives, the proposed composition as a binder contains chlorinated rubber modified with an alkyd resin with an acidity of not more than 20 mg KOH / g and plasticized with chloroparaffin wax in an environment of an organic solvent in the following ratio of components wt.%:

Chlorinated rubber 14.0-19.0 Alkyd resin with acidity not more than 20 mg KOH / g 6.0-9.0 Chloroparaffin Wax 7.0-11.0 Organic solvent rest

as target additives it contains a thixotropic additive in the form of polymerized amphoteric oil, a sedimentation additive - organophilic bentonite and additionally graphite in the following ratio of components, wt.%:

Fine Zinc Powder 48.8-69.6 Organophilic bentonite 0.2-0.3 Polymerization amphoteric oil 0.2-0.3 Graphite 4.0-4.5 Zinc oxide 0.9-1.2 Specified Binder rest

As a highly dispersed zinc powder, any of the well-known imported and domestic grades can be used zinc powder obtained by methods known in the industry and corresponding in chemical and particle size distribution to the requirements of ISO 35: 49: 1995 (E), for example, imported powders - S3 grades (Norway), or EMP, UMP (South Korea), or MSU (India), or 4P32 (Belgium), or KFZn625 (China), or domestic production - PCV (manufactured by NPP Uralavtokhim LLC), or brand PCVD (izg Otovitel ZAO NPP "Fine Metal Powders").

As chlorinated rubber, any chlorinated olefin polymer with a chlorine content of at least 50 wt.% Can be used, for example, PERGUT S20 from BAYER with a chlorine content of 64.5 wt.% Or YURON CR20 from YURON CHEMICAL INUSTRY MATERIAL or other similar products materials.

As an alkyd resin with an acidity of not more than 20 mg KOH / g, semi-finished varnish PF-053 can be used, manufactured according to TU 2311-277-05744283-2007 or TU 2311-059-05788576-2005 by modifying the synthesized pentaphthalic resin with unrefined sunflower oil and a mixture of phthalic anhydride with rosin. Other known pentaphthalic alkyd resins with the indicated acidity may be used.

As a chloroparaffin wax, a mixture of C ₁₀ -C ₁₃ Cereclor 54 DP, 52 DP manufactured by BANG & BONSOMER or any other suitable mixture of chloroparaffins can be used.

As zinc oxide, any industrially produced zinc oxide with a basic substance content of 99.0-99.5 wt.%, Satisfying the requirements of GOST 10262-73, can be used.

Derivatives of amphoteric polymer oil are used as a thixotropic additive, for example, Trotix 42 VA grade manufactured by TROY Corporation based on aromatic petroleum distillates or ST, GST grade Tixatroli based on hydrogenated castor oil modified with organic substances, or another known thixotropic similar additive can be used properties.

As a sedimentation additive can be used any known organophilic bentonite, for example, the brand Bentonite SD ₁ company BANG & BONSOMER.

As graphite, natural graphite of the EUT-2 brand according to GOST 10274-79 or the GK-3 brand according to GOST 4404-78 or graphite of other brands, preferably with a scaly structure of particles capable of performing the function of a filler-pigment, can be used.

As an organic solvent, a medium-polar aromatic solvent, for example xylene or an oil solvent, according to GOST 10214-78 or another acceptable solvent, is used.

Comparison of the proposed composition with the known allows us to conclude that the criterion of "novelty", because the proposed composition contains a new binder, in a new qualitative and quantitative ratio of the ingredients in the composition.

The proposed binder provides for the use of chlorinated rubber modified with alkyd resin and plasticized with chlorinated paraffin wax in an organic solvent. As the basis of the zinc-filled material, the proposed binder has not previously been used. Using the inventive composition made it possible to obtain an unobvious technical result - a uniform stable highly filled dispersion of zinc powder in a binder, which provides a drying time of a single-layer coating at 20 ° C until tack - 15-40 minutes. The coating obtained from the claimed composition has a high chemical resistance to aggressive environments and has a long tread action, which ensures the durability of the corrosion protection of the metal surface. The proposed binder forms complex conductive complexes with the proposed fillers, providing a tread mechanism for surface protection. In addition, studies have shown that the plasticization of chlorinated rubber with chloroparaffin wax provides high hardness, ductility, water resistance of the finished coating, fire resistance of the coating, which acquires the quality of “non-spreading and extinguishing flame”.

The release of hydrogen chloride, which is possible during the thermal hydrolysis of a chlorine-containing binder, is compensated by the introduction of zinc oxide, which in the inventive composition performs the function of a heat stabilizer - an acceptor of hydrogen chloride formed during operation of the coating at elevated temperatures.

The introduction of the inventive composition of graphite as a filler leads to an increase in the resistance of the finished coating to abrasive loads, expanding the scope of application. The inventive coating can be used to seal joints, crevice gaps, protect springs and spring sheets experiencing specific physical loads in combination with an aggressive environment. In addition, the joint introduction of the inventive composition of graphite and highly dispersed zinc powder increases the chemical resistance and heat resistance of the finished coating. The mechanism of the indicated action of such a complex filler in the composition is explained by the fact that when the inventive composition is applied to the surface, light graphite plates float to the surface and protect the zinc from direct contact with the aggressive medium, preventing the formation of a continuous impermeable layer of the products of the interaction of zinc with the medium. Due to this, the duration of the tread properties of the finished coating increases at least 2.0-2.5 times, even when filling the coating with zinc less than 90 wt.%.

Introduction to the composition together with the claimed binder and complex filler of the traditional target antisedimentation and thixotropic additives allows to obtain a zinc-filled dispersion that does not delaminate during long-term storage (more than 12 months) and dilution to working viscosity.

The combined use of the inventive binder and complex filler of finely dispersed zinc powder and graphite in the declared amounts allows to obtain a technical result that has no analogues in comparison with the result of known zinc-filled coatings - allows you to get a coating with indicators of anticorrosion resistance, approaching that of hot-dip galvanized coating with a thickness of 60 microns, as well as with a high shelf life and good technological properties.

The above allows us to conclude that the claimed invention meets the criterion of "inventive step".

The inventive composition can be made from well-known materials of domestic and / or imported, manufactured on an industrial scale and widely represented in the domestic market, as well as using standard paint and varnish equipment. The coating is applied by standard methods adopted in the paint and varnish industry. The above allows us to conclude that the claimed invention meets the criterion of "industrial applicability".

The inventive composition is prepared as follows.

An organic solvent, which is used as xylene or an oil solvent in the claimed amount, is mixed in a high-speed dissolver with chlorinated rubber, which is used as a chlorinated olefin polymer with a chlorine content of 64.5 wt.% Brand PERGUT S20. The mixture is heated to a temperature of 40 ° C or slightly higher and stirred until complete dissolution. There, in the declared amounts, a modifying alkyd resin with an acidity of not more than 20 mg KOH / g is used, for which an alkyd varnish of the PF-053 brand and chlorinated paraffin wax are used, as a mixture of chloroparaffins C ₁₀ -C ₁₃ At the same time, the dissolver in the claimed a quantity of sedimentation additive is loaded, which use Bentonite SD ₁ and a thixotropic additive, which use derivatives of amphoteric polymer oil of the Trotix 42 VA brand. The resulting mixture is dispersed at a constant temperature for 15-20 minutes. Then the mixture is cooled to the temperature of the working room and zinc oxide, graphite, which is used as graphite of grade EUT-2 or grade GK-3, and highly dispersed zinc powder, which is used as zinc powder of grade PCV or grade, are successively introduced into it in the claimed amount KFZn625. The resulting mixture is stirred until ready, discharged from the dissolver to a deoxidizer to cool and remove air bubbles, and then poured into a container.

A binder for the claimed composition is obtained by mixing chlorinated rubber, alkyd resin, chlorinated paraffin wax and an organic solvent in the following ratio, wt.%:

Chlorinated rubber 14.0-19.0 Alkyd resin with acidity not more than 20 mg KOH / g 6.0-9.0 Chloroparaffin Wax 7.0-11.0 Organic solvent rest

The inventive composition is obtained in the following ratio of components, wt.%:

Fine Zinc Powder 48.8-69.6 Organophilic bentonite 0.2-0.3 Polymerization amphoteric oil 0.2-0.3 Zinc oxide 0.9-1.2 Graphite 4.0-4.5 Specified Binder rest

Examples of specific binder formulations are shown in table 1. Examples of specific formulations of the claimed compositions are shown in table 2. Properties of the claimed compositions are shown in table 3.

Samples for testing are prepared in accordance with GOST 8832, GOST 9.402 and ISO 12944-4: 1998 and ISO 8501-1: 1998.

As the sample material, low-carbon steel grades 08 ps or 08 kp, STZ with a sheet thickness of 0.8-1.0 mm were used. The surface preparation of the samples was carried out by cleaning with a solvent, which used white spirit, solvent, xylene, R-4, R-5 solvents, as well as by subsequent dry blasting. The surface roughness in terms of Rz was 40-60 microns.

Test samples were prepared according to current GOST. The coating is applied by methods of pneumatic, airless spraying or brush, roller. If necessary, the material before coating was diluted to a working viscosity with xylene or solvent, or with solvents P-4 or P-5. The resulting coating was dried under natural conditions for 15-40 minutes, depending on the thickness of the coating, temperature and humidity. The thickness of a single-layer coating depends on the method of its application and is 30-80 microns. Before testing the physicochemical and mechanical properties, the coating is aged at room temperature for more than 7 days. Drying time is determined in accordance with GOST 19007, adhesion of the coating to a metal surface is determined in accordance with GOST 15140, method 2, impact strength is determined in accordance with GOST 4765, coating elasticity in bending is determined in accordance with GOST 6806. Density of the claimed composition is determined in accordance with GOST 28513, viscosity in accordance with a viscometer VZ-246 with a 4 mm nozzle in accordance with GOST 8420. The mass fraction of non-volatiles was determined in accordance with GOST 17537, the resistance to static exposure to liquid media was determined in accordance with GOST 9.403, method A. The chemical resistance of the coating was tested in 25 and 60% sulfur solutions acid at a temperature of 20 ° C according to GOST 367-73 and sodium hydroxide according to GOST 4328-77. After testing, the condition of the coating is evaluated according to GOST 9.407. The heat resistance of the coating is determined according to OST 6-10-422-78. The tread properties are determined by measuring the kinetics of the change in the electrode potential by direct potentiometry and are practically confirmed by the results of the state of the metal on an artificially created defect - a scratch according to ISO 4623 for the absence of rust and filament corrosion on the scratch, which leads to the occurrence of a dangerous process of sub-film corrosion. The standard potential is determined according to TU 2313-015-50316079-2004. The data obtained for coatings made from the claimed compositions are shown in table 4.

Requirements for coatings according to normative and technical documentation:

lattice adhesion no more than 4 points impact strength no more than 100 cm bending elasticity no more than 10 mm initial stationary potential relative to silver chloride electrode no more - 0.95 V

As can be seen from the data given in table 4, the coating obtained from the claimed composition is characterized by high mechanical, abrasive properties, high impact resistance, ductility and resistance to highly aggressive environments in which all previously known zinc-filled paint materials are not stable.

With an increase in the amount of fine zinc powder introduced above the claimed limit, the applied layers have a greater thickness and, as a result, high porosity, which can lead to chipping of zinc particles from the coating under mechanical stress. With a decrease in the amount of zinc powder introduced below the claimed limit, the protective mechanism of protection is not achieved.

With a decrease in the amount of modifying resin of alkyd and plasticizing chloroparaffin wax in the binder below the stated limits, the corrosion and chemical resistance of the coatings decrease, adhesion to the steel substrate and ductility are reduced. With an increase in the amount of modifying resin of alkyd and chloroparaffin wax in the binder above the upper limit, the drying time increases, and the chemical resistance deteriorates.

With a decrease in the amount of graphite below the lower limit, a substantial increase in the duration of the tread properties of the coating is not achieved, the chemical resistance and heat resistance of the coating are reduced.

The manufacture of compositions in ratios that do not correspond to the claimed amounts, leads to a significant reduction in the technological and protective properties of the coatings.

The inventive composition is a one-pack composition, satisfies the requirements for anticorrosive compositions, and can be used as a paint and varnish coating for tread corrosion protection of products and structures made of ferrous metals, operating in medium and high aggressive environments of category C3-C5-M according to classification ISO 1244-2: 1998 at temperatures up to 150 ° C - salt spray, vapors and aerosols of acids, alkalis, solutions of salts, acids and alkalis, variable exposure to acid-alkali, and the fresh, sea water and soil categories Im1, Im2, Im3 respectively. The coatings of the claimed compositions are also stable when in contact with crude oil and oil products, acetic acid and its anhydride, providing high corrosion and chemical resistance of the treated metal surface.

The inventive composition can be used to obtain an independent coating, as well as to obtain a primer coating in complex protective and decorative systems in combination with coating enamels based on epoxy, chlorovinyl, urethane, chlorinated rubber binders, chlorinated, chlorosulfonated polyethylene, etc.

The inventive composition has high sedimentation stability during long-term storage (more than 12 months) and dilution to working viscosity, the technologically convenient speed of natural drying to a degree of 3 in 15-40 minutes, provides anti-corrosion coatings with increased adhesion, ductility, long-term tread protection in excess of 2.0-2.5 times the duration of the protective properties of conventional anti-corrosion compounds, chemical resistance in environments characterized by pH 3-12.

Table 1
Binder compositions for compositions of the invention No. Name of ingredients Examples of the invention wt.% one 2 3 one Chlorinated rubber Pergut S20 14.0 17.0 19.0 2 Alkyd resin with acidity no more 6.0 7.0 9.0 20 mg KOH / g-varnish brand PF-053 3 Chloroparaffin Wax 7.0 10.0 11.0 Brand Cereclor 54 DP four Organic solvent: - xylene 73.0 66.0 - - oil solvent - - 61.0

table 2
The compositions of the compositions according to the invention Name of ingredients, wt.% Examples of the invention one 2 3 four Binder: - according to example 1 25.0 - - - - according to example 2 - 30,0 36.00 - - according to example 3 - - 45.0 Fine Zinc Powder: - Stamps PCV 69.6 - 57.8 - - Stamps KFZn625 - 64.5 - 48.8 Graphite: - brands EUT-2 4.0 . .. 4,5 - brand GK-3 .. 4.0 4,5 - Bentonite SD ₁ 0.2 0.2 0.3 0.3 Trotiks 42 VA 0.3 0.3 0.2 0.2 Zinc oxide 0.9 1,0 1,2 1,2

Table 3
Properties of the claimed compositions Name of indicator Examples of compositions of the invention one 2 3 four Appearance: - after prolonged storage in stationary conditions Homogeneous plastic viscous dispersion without sediment - after thorough mixing Homogeneous homogeneous suspension of dark gray color without lumps Density, g / cm ³ 2.5 2.5 2,3 2.2 Conditional viscosity on the viscometer B3-246c with a nozzle diameter of 4 mm at 20 ± 0.5 ° C, s fifty 45 40 thirty Mass fraction of nonvolatile substances,% 81 78 73 66 Consumption for a single layer coating, g / m ² 250 200 200 180 Life span, months More than 12 More than 12 More than 12 More than 12

Table 4
Properties of coatings obtained from the claimed compositions Name Examples of compositions of the invention indicator one 2 3 four Color and appearance Dark gray, slightly Gray Gray rough matte semi-gloss Single layer thickness 80 60 fifty 40 (dry) microns Drying time to 40 thirty thirty fifteen degree 3 at 20 ± 2 ° C, min Adhesion points one one one one Impact strength, cm one hundred one hundred one hundred one hundred Elasticity with 2 2 one one bend mm Coating Resistance 20 ± 2 ° C to static exposure, h: - water 540 540 540 540 - crude oil 300 300 300 300 - industrial oil 250 250 250 250 - solution "sea 600 600 600 600 salt" Heat resistance at 8 8 8 8 150 ° C Resistance to coating acid exposure and alkalis at 20 ± 2 ° С, h: - a solution of H ₂ SO ₄ , 25% - 300 300 300 300 ny; 300 300 300 300 - NaOH solution, 25% - ny Resistance of coating with notched with temperature 40 ± 5 ° С and humidity 80 ± 5% in 600 600 600 600 presence of traces NaCl, h Acetic acid 18% - one hundred one hundred one hundred one hundred at 20 ± 2 ° С, h

Claims (1)

Anticorrosive coating composition containing highly dispersed zinc powder in a binder medium, zinc oxide and target additives, characterized in that it contains chlorinated rubber modified with an alkyd resin with an acidity of not more than 20 mgKOH / g and plasticized with chloroparaffin wax in an organic solvent medium in the following the ratio of components, wt.%:
Chlorinated rubber 14.0-19.0 Alkyd resin with acidity not more than 20 mgKOH / g 6.0-9.0 Chloroparaffin Wax 7.0-11.0 Organic solvent Rest,
as target additives it contains polymerized amphoteric oil, organophilic bentonite and, in addition, graphite in the following ratio of components, wt.%:
Fine Zinc Powder 48.8-69.6 Organophilic bentonite 0.2-0.3 Polymerized amphoteric oil 0.2-0.3 Graphite 4.0-4.5 Zinc oxide 0.9-1.2 Specified Binder rest