RU2304602C1 - Composition for production of the antirust coating - Google Patents

Abstract

FIELD: ferrous metallurgy; oil refining industry; building industry; chemical industry; compositions for production of the anticorrosive zinc-containing base coatings.

SUBSTANCE: the invention is pertaining to the compositions for production of the anticorrosive zinc-containing base coatings intended for a sacrificial protection from corrosion of the products, buildings and constructions made out of the ferrous metals exploited in the atmospheric conditions, in the conditions of water-saline mist, in the medium of the oil products vapors and aerosols. The composition for production of the antirust coating includes the fine-dispersive zinc powder, the three-metal desiccant, the toluene, the modified alkyd film-forming substance, in the capacity of which they use the short-alkyd varnish with addition of the tung oil, modified with the phenol-formaldehyde resin in amount of no more than 5.0 % of the mass of the alkyd film-former, with the acid number of no more than 15.0 mgKOH/g of the film-former and the dynamic viscosity after Brunkfild - 2.0-4.5 Pa·s, and the antisediment additive, in the capacity of which use the admixture of zinc oxide, lecithin and the organophilic bentonite of SD-1 brand. The composition has the high sediment stability at storing and at coating, dries faster and ensures production of the antirust coatings with the heightened resistivity to the water and petroleum action.

EFFECT: the invention ensures production of the composition having the high sediment stability at storing and coating, the fast drying and used for application of the antirust coatings with the heightened resistivity to the water and petroleum action.

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Description

The present invention relates to compositions of anticorrosive zinc-containing primers designed for tread protection against corrosion of products, structures and structures made of ferrous metals, operated in atmospheric conditions, in conditions of water-salt fog, as well as in vapors and aerosols of oil products.

The inventive anticorrosive composition can be used both to obtain an independent primer coating, and to obtain multilayer protective and decorative coatings by covering with enamels such as PF, ML, EP, etc.

The scope of metallic zinc in the technique of corrosion protection is quite extensive. Hot dip galvanized metal coatings from zinc melt insulate steel and cast iron products from the atmosphere with an impenetrable layer and have a double effect on protected surfaces. Upon contact with moist air, zinc corrodes and its decomposition products form a barrier that prevents further penetration of aggressive media into the coating. When mechanical defects appear on the coating (chips, pores, scratches, etc.), the zinc coating protects this area locally. In this case, a galvanic pair between iron and zinc, where zinc acts as an anode, is provided by a thin film of water, which always exists on the surface in a humid atmosphere.

A more progressive method of anticorrosion protection of ferrous metal products using metal zinc from an environmental and technological point of view is currently the so-called "cold galvanizing" method - this is applying to the prepared surface by methods used for conventional paints and varnishes, special zinc-containing compounds based on various polymer film formers, as a result of which highly zinc-coated coatings are formed, possessing the same anti-corrosion voystvami like coating obtained by the method of "hot galvanizing".

Existing zinc-containing compositions are available both in a single-pack version and in a two-pack form, that is, part of the constituent components — zinc powder or hardener — are introduced into the composition immediately before painting.

Single-pack compositions are more technologically advanced when used. Known anti-corrosion zinc-rich composition containing the following ingredients (wt.%):

fine zinc powder, obtained by physical deposition from the vapor phase, with a mass fraction of particles size from 4 to 12 microns not less than 55%, mass fraction of particles larger than 20 microns no more than 15%  47.0-87.0 thermoplastic film former high molecular weight polystyrene and / or styrene rubber copolymer 1.3-5.1 an organic solvent is xylene or solvent or mixture of xylene with butyl acetate and / or acetone  the rest is up to 100

The specified composition may additionally contain surfactants in an amount of up to 0.4 wt.% Of the total weight of the ingredients, rheological additives in an amount of up to 3.0 wt.% And fillers - not more than 15.0 wt.% Of the total mass. (RF patent No. 21411984. IPC ⁶ C 09 D 5/08. Anticorrosive composition. Application. 07/01/97, application No. 97111012/04. Publ. 27.11.99).

A disadvantage of the known composition is the low resistance of coatings based on it to the effects of petroleum products and fuels and lubricants, due to the chemical nature of the thermoplastic film former, which limits the scope of its use. In addition, such protective coatings do not withstand shock loads and vibration.

The closest analogue to the claimed technical essence and formulation is a zinc-filled primer containing in its composition the following components (wt.%):

modified pentaphthalic varnish epoxy fatty acid oligomer, a product of interaction low molecular weight epoxy diane resin and taly oil or its fatty acids when their mass ratio of 5: 2, with pentaphthalic varnish weight ratio and epoxy fatty acid oligomer 4: 1 41.5-61.5 zinc powder 30.0-45.0 polymethylurea 6.5-10.0 desiccant 2.0-3.5

(RF patent No. 2068434. IPC ⁶ 09 D 167/08; 5/08. Primer. Application. 20.10.92, application No. 92001217/04. Publish. 27.10.96. Bull. No. 30, prototype).

The prototype composition is technologically advanced during application and allows to obtain anti-corrosion coatings with increased elasticity. However, it has insufficient sedimentation stability (zinc deposition) during storage, as well as during application, when it is used in diluted form to a working viscosity level (15-20 s with a VZ-246 type viscometer with a nozzle diameter of 4 mm at a temperature of 20 ± 2 ° C). This is due to the fact that polymethylurea, although it is a thickening agent, does not impart a thixotropic effect to the composition. In addition, the use of a pentaphthalic (alkyd) film former in the primer does not allow oil and petrol-resistant anti-corrosion coatings to be obtained, and the time of their formation (drying) before obtaining the required physical and mechanical properties exceeds 22 hours, which slows down the painting work.

The technical problem solved in the framework of the present invention is the creation of the formulation of the zinc-filled composition with high sedimentation stability, both during storage and during application, and providing a reduction in drying time and obtaining an oil and petrol-resistant anti-corrosion coating.

The solution to this goal is achieved due to the fact that, in contrast to the known prototype composition, the proposed composition for obtaining an anti-corrosion coating, including highly dispersed zinc powder, a modified alkyd film former, a three-metal desiccant and an anti-sedimentation additive, additionally contains an organic solvent, toluene, as a modified alkyd film former it contains lean alkyd varnish with tung oil, modified phenol-formaldehyde resins minutes in an amount of not more than 5.0% by weight of the alkyd film former, having the following characteristics:

acid number in terms of 100% alkyd film former (i.e. without solvent), mgKOH / g, not more than 15.0 Brunkfield dynamic viscosity at (20 ± 2) ° С, Pa · s  2.0-4.5

and as an anti-sedimentation additive, the claimed composition contains a mixture of zinc oxide, organophilic bentonite grade SD-1 and phosphatide concentrate (lecithin), in the following ratio between the components of the composition (wt.%):

specified modified alkyd film former  10.0-15.0 fine zinc powder  55.0-65.0 organophilic bentonite SD-1  0.3 - 0.8 lecithin  0.3-0.8 three-metal desiccant  0.1-0.3 zinc oxide  10.0-15.0 toluene  rest

As a modified alkyd varnish, 51-61% solutions of AF-033 alkyd-phenolic resin (TU 2311-025-54651722-2002) or AMF 30x60 alkyd-phenolic resin (TU LVUTN-40003245470-10-02) in xylene are used. Varnish AF-033 according to color specifications has not more than 80 mg J _2/100 cm ^3, an acid number of not more than 15.0 mg KOH / g, a dynamic viscosity of 2.0-4.0 Pa · s milk the nonvolatile mass ± 53 2%, the content of the modifier 3-5 wt.%. Nail according AMF 30x60 chrominance specifications has not more than 20 mg J _2/100 cm ^3, an acid number of not more than 15 mgKOH / g, a dynamic viscosity at 20 ° C 3.0-4.5 Pa · s, a mass fraction of non-volatiles 59-61%, the content of the modifier is 1.8-3.0 wt.%. As a finely dispersed zinc powder, any imported metal (with an average particle size of 3-5 microns) is used, for example, S3 (Norway) or EMP, UMP (South Korea).

As a three-metal desiccant, the ZhK-12 (TU 6-21-02041501-90) or LB-2 (TU LV TN 000324547-03) driers are used. Desiccant ZhK-12 according to the technical conditions is a solution in white spirit of a mixture of lead, cobalt and manganese octoates with a mass fraction of metals: Pb 8.0 ± 0.1%, Mn 2.0 ± 0.1%, Co 0.8 ± 0.1%. The metal content of the LB-2 desiccant is as follows: Pb 15.0 ± 0.3%, Mn 0.9 ± 0.1%, Co 1.2 ± 0.1%. Zinc oxide is used in accordance with GOST 202-84 of any brand, oil toluene - in accordance with GOST 14710-78.

The phosphatide concentrate is used in the form of soya lecithin according to TU 9146-203-00334534-97, organophilic bentonite is used SD-1 brands manufactured in the UK.

The indicated limits of the ratios between the components of the composition are determined experimentally and are optimal from the point of view of achieving a positive technical effect and minimal cost.

The decrease in the content of the film-forming agent in the composition below 10.0 wt.% Leads to a coating with low physical and mechanical properties (elasticity, adhesion, resistance to shock). During the operation of such a coating, its chalking is observed - chipping of zinc powder. The use of more than 15.0 wt.% Film former in the composition is impractical from an economic point of view, as well as due to the deterioration of the tread properties of the coating associated with a violation of the contact between the particles of the metal filler. The amount of three-metal desiccant introduced is directly related to the content of the film former in the composition.

Comparison of the claimed composition with the known composition of the primer allows us to conclude that it meets the criterion of "Novelty", as in this case contains a new set of ingredients in a new quantitative ratio.

In the production of anticorrosive zinc-containing coatings, the use of various polymer film-forming agents is known. Our proposed composition for the first time contains as a polymer base a skinny alkyd resin with the addition of tung oil, modified with a phenol-formaldehyde resin. Its use only in conjunction with anti-sedimentation additives - zinc oxide, lecithin and organophilic bentonite SD-1 - led to an unobvious effect - to obtain a low-viscosity zinc-rich composition that does not delaminate during long-term storage (more than 8 months) and has a significantly lower rate of deposition of zinc particles in consumables containers when applied. The drying time of the coating is significantly reduced. It acquires resistance to the effects of petroleum products and fuels and lubricants. The above indicates that the proposed technical solution meets the criterion of "Inventive step".

The introduction of zinc oxide into the composition improves not only antisedimentation properties due to its chemical interaction with the free carboxyl groups of the modified alkyd film former, but also allows to reduce the cost of the composition due to the partial replacement of expensive highly dispersed zinc powder, and by reducing the density of the composition (the latter leads to reduce the consumption of the composition per unit of protected surface). At the same time, the protective treading properties of the formed coating are preserved: this is evidenced by the fact that rust does not form in the artificially created defect-scratch, i.e. anticorrosive protection of steel is carried out by the cathodic mechanism.

The proposed formulation of the anticorrosion composition is focused on the use of ingredients produced on an industrial scale, using standard equipment for paint and varnish production to obtain it. It can be applied to protected surfaces using any of the existing methods: brush, roller, dipping, air or airless spray methods. This allows you to make a reasonable conclusion about the compliance of the proposed technical solution to the criterion of "Industrial applicability".

The composition is obtained by dispersing in a high-speed dissolver fillers and additives in a solution of a modified alkyd film former to the required degree of dispersion (the degree of milling on the Klin device is less than 30 microns), followed by filtering the resulting suspension through a filter with a mesh filter mesh size of 35-40 microns.

Samples of coatings for testing on plates made of steel of grade St.3 with a size of 150 × 70 × 0.8 mm were obtained by air spraying followed by drying at room temperature to degree 6 (GOST 19007-73). The thickness of the formed coatings was 70-80 microns.

The conditional viscosity of the composition was determined by a viscometer of type B3-246 with a nozzle diameter of 4 mm at a temperature of 20 ± 2 ° C according to GOST 8420-74.

The stability of the composition during storage is visual. The delamination of the diluted composition was evaluated according to GOST 25129-82 (Clause 4.11).

The drying time of coatings to degree 3 was evaluated according to GOST 19007-73 at a temperature of 20 ± 2 ° C.

The adhesion of coatings by the method of "trellised notches" was determined according to GOST 15140-78, the strength of the coatings upon impact was determined according to GOST 4765-78, and the bending elasticity was determined according to GOST 6806-73.

The resistance of the coating to the static effects of water and oil products at a temperature of 20 ± 2 ° C was determined according to GOST 9.403-80.

The technical nature and advantages of the proposed zinc-filled composition for producing anti-corrosion coatings are illustrated by the following experimental data.

EXAMPLE

The components of the composition and primer prototype for the particular formulation are weighed (Table 1), dispersed in a laboratory dissolver with a capacity of 1.0 dm ³ , after which samples of anticorrosive coatings are prepared from the obtained materials, the test results of which are shown in Table 2.

Table 1 The compositions of anti-corrosion compositions Components The content in the compositions (wt.%) 1 (prototype) 2 3 four 5 6 7 8 Alkyd varnish, modifi cited epoxy fatty acid oligomer 51.5 - - - - - - - Skinny alkyd varnish with adding tung modified oils phenol formaldehyde resin: AF-033 (mass fraction modifier 4.6%) - - 15.0 - 8.0 17.0 - - AMF 30x60 (mass modifier share 2.9%) - 10.0 - 14.0 - - 12.5 12.5 Fine zinc powder 37.5 55.0 65.0 57.3 60.0 60.0 50,0 70.0 Polymethylurea 8.25 - - - - - - - Three-metal desiccant LCD 12 2.75 - 0.3 - 0.1 0.5 - - LB-2 - 0.1 - 0.2 - - 0.2 0.2 Organophilic bentonite m. SD-l - 0.8 0.3 0.5 0.2 1,0 0.5 0.5 Soya lecithin - 0.8 0.3 0.5 0.2 1,0 0.5 0.5 Zinc oxide - 15.0 10.0 13.5 8.0 8.0 12.5 9.5 Toluene Oil - 18.3 9.1 14.0 23.5 12.5 23.8 6.8

table 2
Properties of compositions and anticorrosion coatings based on them The name of indicators Compositions from table 1 one
(prototype) 2 3 four 5 6 7 8 1. The conditional viscosity of the compositions, s 95.0 22.0 48.0 41.0 28.0 39.0 24.0 35.0 2. The stability of the compositions during storage unchanged, months 4.0 8.0 8.0 8.0 5,0 6.0 8.0 8.0 3. The delamination of diluted compositions, cm ³ 20,0 1,0 3.0 5,0 12.0 6.0 10.0 4.0 4. Drying time to degree 3, h 22.0 1,0 2.0 1,5 1,5 2.5 2.0 1,5 5. Adhesion of the coating to the metal substrate, points one one one one one one one 2 6. The elasticity of the coating in bending, mm one one one one 3 2 2 3 7. The strength of the coating upon impact, J 5,0 5,0 5,0 5,0 3.0 5,0 5,0 2.0 8. Resistance to static exposure to media:   water 72.0 96.0 96.0 96.0 48.0 72.0 48.0 48.0   raw oil 24.0 72.0 72.0 72.0 72.0 60.0 72.0 72.0   industrial oil I-20A 48.0 96.0 96.0 96.0 72.0 60.0 72.0 72.0   diesel fuel 8.0 48.0 48.0 48.0 48.0 36.0 48.0 48.0

Thus, as can be seen from comparative examples, the inventive zinc-enriched composition with comparable viscosity has a higher level of sedimentation stability in both the original and diluted form, as well as a significantly shorter drying time compared to the prototype primer and provides anti-corrosion coatings having comparable indicators of physical and mechanical characteristics (adhesion, elasticity, impact strength), greater resistance to water and oil products.

Claims (1)

The composition for obtaining a corrosion-resistant coating, comprising fine zinc powder, a modified alkyd film former, a three-metal desiccant and an anti-sedimentation additive, which further comprises an organic solvent - toluene, as an alkyd film former contains a skinny alkyd varnish with the addition of tung oil, a modified phenol- formaldehyde resin in an amount of not more than 5.0% by weight of alkyd film former, with an acid number of not more than 15.0 mgKOH / g of film former and with a Brunkfield dynamic viscosity of 2.0-4.5 Pa · s, and as an anti-sedimentation additive it contains a mixture of zinc oxide, organophilic bentonite and lecithin in the following ratio of composition components, wt.%: specified modified alkyd film former 10.0-15.0 fine zinc powder 55.0-65.0 organophilic bentonite SD-1 0.3-0.8 lecithin 0.3-0.8 three-metal desiccant 0.1-0.3 zinc oxide 10.0-15.0 toluene rest