RU2349618C2 - Coating, filled with hollow microspheres, preventing ice-covering of surfaces of different objects - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention pertains to a coating, preventing ice-covering of different surfaces and objects, especially pipes, electrical cables, metal, concrete, plaster etc, and with anticorrosion and heat insulating properties at the same time. The coating is made from a water dispersion composition with viscosity 1-100 Pa·s, containing a polymer binder in form of a 5-95 vol. % polymer latex composition, containing 10-90 vol. % (co)polymer, chosen from a group, comprising acrylate homopolymer, styrene-acryl copolymer, butadiene-styrene copolymer, polystyrene, butadiene polymer, polyvinylchloride polymer, polyurethane polymer, vinyl acetate (co)polymer or their mixture and 5-95 vol. % mixture of hollow microspheres with diameter varying from 10 to 500 mcm and different packed density from 650 to 50 kg/ m³, chosen from a group, comprising hollow glass microspheres, hollow ceramic microspheres, hollow polymer microspheres, hollow technogenic (ash) microspheres or their mixture and from 10 to 90 vol. % mixture of water and a surface active substance, and deposited, at least, in form one layer on the protected surface, with subsequent drying of the coating.

EFFECT: increased effect of the coating.

2 tbl

Description

The invention relates to the chemical industry and relates to the creation of tools used to prevent the icing of the surfaces of various products, especially those requiring simultaneous corrosion protection and thermal protection, i.e. protection of various surfaces from overheating, and from icing, and from corrosion. In particular, it can be used to protect metal surfaces, concrete surfaces, plastered surfaces and other metal and concrete building structures operating at low temperatures in an atmosphere of aggressive environments, in particular for thermal insulation and corrosion protection of pipelines, including thermal insulation of thermal pipelines and water supply, as well as electrical wires, gas and oil pipelines, for thermal insulation and corrosion protection of roofs, walls of houses and other elements in housing construction, about Especially operated in specific and rather severe conditions, in particular in permafrost areas, under water and at large changes in temperature and pressure, as well as when exposed to high temperatures, exposure to superheated steam.

Therefore, the invention can be used in housing and communal services, the construction of various structures, oil, gas and petrochemical industries, the electrical industry and other industries.

Known two-layer anti-icing coating (SU 739080, 06/05/1980) based on tetraethoxysilane containing in the first layer tetraethoxysilane in an amount of 1-30 vol.%, A complex catalyst - 0.18-5.2 vol.% And an organic solvent, and in the second - polyethyl hydrosiloxane liquid in an amount of 5-2 wt.%, an adhesive active catalyst - 0.3-1.2 wt.% and an organic solvent. The composition for the first coating layer is prepared by mixing an organic solvent with a complex catalyst, tetraethoxysilane is added to the resulting solution, and stirred for 24-48 hours. The duration of mixing is determined by the need for "aging" of the solution. The shelf life of such a composition is short and therefore it is prepared immediately before use. The composition for the second layer is prepared by dissolving polyethylsiloxane in an organic solvent, followed by adding an adhesive catalyst to the resulting solution. For the coating thus obtained, the force of separation of ice from the protected surface is 0.04-0.08 kgf / cm ² . The method for determining the adhesive strength is not given, therefore, the data presented cannot be considered absolute. The number of freezing cycles characterizing the durability of the coating is 15-17. In addition, to create layers of the described coating using compositions with a very high content of volatile organic solvents: up to 60-80%. This composition in addition does not provide the necessary thermal insulation properties.

Another composition is known for the preparation of the anti-icing coating Krezan (SU 1386630, 06.24.1986) based on polyorganosiloxane in an amount of 42-49 wt.% In an organic solvent, containing a filler hydrophobized with organosiloxanes or paraffin, or stearic acid in an amount of 2-15 wt. .%, selected from the group comprising silicon dioxide, titanium dioxide, zinc oxide, expanded graphite, basalt fiber and mixtures thereof. Preliminary hydrophobization of the filler requires drying of all components of the composition and prolonged evacuation at an elevated temperature in the range of 290-420 ° C. The adhesion force of ice with the coating does not exceed 0.09 kg / cm ² . The methodology is also not given. The critical angle of water rolling is 25-30 degrees, the hardness of the coating is 0.4 (for the M-3 device). The service life of this anti-icing coating, for example, refrigerators, take-off areas, is 2 years. This composition also does not provide the necessary anti-corrosion and heat-insulating properties.

A known composition for anti-icing coatings (SU 1712388, 02.15.1992). The specified composition contains as a polymeric binder an organosilicon resin in an amount of 25-45 wt.%, A filler selected from the group consisting of zinc oxide, magnesium oxide, titanium dioxide or expanded graphite, while the filler is hydrophobized with organic modifiers, for example methyl chloroform, ethyl silicate resins or organopolysiloxysiloxane liquid in an amount of 16-30 wt.%, and a solvent. The anti-icing properties of the coating known are mainly due to the presence of a hydrophobized filler in the composition, and its hydrophobization is a complex and labor-intensive technological operation. The adhesion of this coating to the substrate is satisfactory, while the service life of the coating is only 3 years. The coating is not intended to simultaneously perform the function of anti-corrosion and thermal insulation coating.

Another anti-icing composition is known from RU 2156786, 09.27.2000, which also includes an organosilicon polymer binder consisting of polydimethylphenylsiloxane and polydimethylsiloxane and toluene; talc or a mixture of it with belite and / or barite is used as a filler; oxides and / or salts of transition metals are used as a pigment. This known invention allows to obtain a coating that combines good anti-icing properties and protective properties, however, the coating has insufficient film strength, low chemical resistance and does not provide the necessary thermal insulation and anti-corrosion properties, in addition, it is not used for coating wires.

So, despite the large number of known compositions for this purpose, the problem of anti-icing by using coatings is still relevant and is not completely solved for the following reasons. Considered known anti-icing coatings have low adhesion to ice, snow and other crystalline forms of water. However, while providing relatively good icing protection over a relatively short period of time, known coatings do not retain anti-icing properties over a long service life. In addition, all of them do not simultaneously provide reliable corrosion protection of various surfaces, especially pipelines and electrical wires, cables, as well as from overheating them, i.e. not used for thermal insulation.

The claimed invention relates to the production of coatings intended for the simultaneous protection of surfaces (various, including painted) products from icing, corrosion and thermal protection.

It is known, in particular, the use of compositions based on liquid glass with various fillers - expanded vermiculite, dolomite (RU 2126776, 02.27.1999) or hollow microspheres in the form of fly ash of thermal power plants (SU 1724524 07.04.1992, GB 1550184, 1979), or a mixture of glass microspheres with microspheres in the form of flue waste from coal combustion with a particle size of 10-300 microns (RU 2098379 12/10/1997) for thermal insulation, but these compositions are not used as anti-icing coatings.

In addition, all of these known compositions are intended to produce heat-insulating materials, but not in the form of coatings, but, for example, in the form of heat-insulating plates, which limits their use. A known composition is used, in particular, to protect the surfaces of metal pipelines against corrosion, including styrene butadiene latex as a binder, water glass, alite cement, quartz sand, latex stabilizer, trisodium phosphate, fiberglass and water (SU 1717580, 03/07/1992) . However, this composition also does not provide the necessary complex of thermal insulation properties of the coating, and also does not simultaneously perform the function of an anti-icing coating.

From RU 2251563, 05/10/2005, an anti-corrosion and heat-insulating coating based on a polymer binder in the form of a polymer latex composition in combination with hollow microspheres is known. As hollow microspheres, it contains a mixture of hollow microspheres with different sizes from 10 to 500 μm and various bulk density from 650 to 50 kg / m ³ , selected from the group of hollow glass microspheres, hollow ceramic microspheres, hollow polymer microspheres, hollow ash (man-made) microspheres or mixtures thereof.

Known anti-corrosion and thermal insulation coating additionally contains various targeted additives.

This claimed invention is a further improvement of the above invention - a well-known coating, the author of which is the author of this claimed invention from the point of view of its previously unknown application.

In the process of using it, it was unexpectedly discovered that this known coating under certain conditions can be used as an anti-icing coating, especially for protection against icing of electrical wires, electric cable.

So the technical task of the claimed invention is the creation of an anti-icing coating having both anti-icing and thermal insulation properties.

The problem is achieved by the use of anticorrosion and thermal insulation coatings as a coating that prevents icing on the surfaces of products operating at low temperatures, and is made of a water-suspension composition with a viscosity of 1 to 100 Pa.s, containing a polymer binder and hollow microspheres, and applied at least at least in the form of one layer on the surface to be protected, followed by drying of the coating, while the composition contains a water-based emulsion (or dispersion) latex composition comprising 10-90 vol.% (co) polymer selected from the group consisting of acrylate homopolymer, styrene-acrylic polymer, styrene butadiene copolymer, polystyrene, butadiene polymer, polyvinyl chloride polymer, polyurethane polymer, (co) a vinyl acetate polymer or mixtures thereof, and 10-90 vol.% a mixture of water and a surfactant and, if necessary, target additives, while the composition contains a mixture of hollow microspheres of different sizes (with different sizes) from 10 to 500 as hollow microspheres μm and with p different bulk density from 650 to 50 kg / m ³ , and selected from the group consisting of hollow glass microspheres, hollow cramic microspheres, hollow polymer microspheres, hollow man-made (or otherwise ash) microspheres or mixtures thereof, in the following ratio of water-suspension components composition, vol.%:

polymer latex composition 5-95 the above hollow microspheres 5-95

This coating, as it was discovered when applying it, in particular, to electric wires, prevents icing of surfaces, performing at the same time the function of anti-corrosion and thermal insulation coating. It may additionally contain various target additives, such as white and colored pigments, corrosion inhibitors (sodium nitrite, sodium benzoate, guanidine derivatives, zinc tetraoxychromate, AKOR-1, NG-203 additives in conventional amounts), flame retardants, such as aluminum trihydrate, ammonium polyphosphate, zinc borate, mica, asbestos and others. As a polymer binder, the composition used to obtain an anti-icing coating contains various polymer latexes, possibly stabilized previously, such as latexes based on copolymers of vinyl acetate with ethylene, methyl methacrylate and methacrylic acid (E-BC-17 paint base), based on polyvinyl acetate dispersion ( 50%) in the form of latex paint E-VA-0112 and others; latex systems based on styrene-butadiene copolymer SKS-65 GP, BS-30, based on acrylic copolymers DMMA-1-65 GP, as well as based on styrene acrylic copolymers from Dow Chem, Primal 219, acrylurethane latexes.

So, the invention consists in the use of a coating filled with hollow microspheres with certain parameters of their size and bulk density, as a multifunctional coating, i.e. as a coating that prevents icing of the surfaces of various products and at the same time protects them from corrosion, as well as a thermal insulation coating.

The application of the claimed invention helps to improve the thermal insulation properties of coatings of various surfaces operating in specific harsh conditions, including at low temperatures, while protecting them from corrosion, improving environmental properties and simplifying the technology for coating.

In the claimed invention, the use of mixtures of hollow microspheres (glass, ceramic, polymer, ash), identical or different in nature, but differing in size in the range from 10 to 500 μm and bulk density in the range from 50 to 650 kg / m ³ allows significantly to increase the efficiency of heat and corrosion protection of surfaces (concrete, plaster, metal, wood), as well as provide protection against icing of surfaces.

Such properties of hollow microspheres, such as low oil absorption, inertness and ease of dispersion, make them very attractive as fillers.

Hollow microspheres of glass, ceramics, polymers are mainly obtained by introducing a blowing agent into the main material, then grinding them to the desired size and heating them to foam. So, for example, hollow microspheres are obtained by passing small particles containing a porophore through a high-temperature zone; the particles melt or soften in the hot zone, and the blowing agent forms a cavity inside the particles, expanding them. When the sphere is cooled in air, its walls harden. Or they are obtained by foaming glass (or ceramic, ash) particles in a burner flame. As hollow glass microspheres use, for example, microspheres such as Glass babez, such as Microballon; globumite, spherulite. Ceramic microspheres are also obtained by burning natural materials and foaming; ash or man-made are obtained, for example, from fly ash.

Polymeric hollow microspheres are obtained, as a rule, either by suspension polymerization of monomers with the addition of a blowing agent (porophore, inert gases, low boiling hydrocarbons), or by physical or chemical foaming of ready-made polymers in the form of ground particles. As the hollow polymer microspheres, the invention uses polystyrene hollow microspheres based on phenol-formaldehyde resins, silicone, urea-formaldehyde, etc.

So, the claimed invention is the use of a composition filled with hollow microspheres, as a coating to prevent icing of surfaces operating at low temperatures, as well as an anti-corrosion and heat-protective coating on various surfaces. One of the main components is hollow glass, ceramic, polymer, ash (technogenic) microspheres filled with rarefied or atmospheric air. The second main component of the applied coating composition is a binder, the function of which is performed by the above polymer latex systems.

An anti-icing coating is prepared as follows.

An aqueous mixture (aqueous dispersion) is prepared on the basis of styrene-acrylic latex, mixing it with hollow microspheres, for example, glass microspheres of three types of sizes (with radiuses of microspheres of 35, 100, 200 microns and with apparent densities of 650, 150, 70 kg / m in proportion to 3: 6: 1, respectively), possibly titanium dioxide or zinc oxide, a surfactant, OP-10, and also a rust inhibitor. The volume ratio of binder to glass microspheres is, in particular, 1:10.

The prepared mixture was applied to the surface of, for example, a metal pipe of heat supply, which was filled with superheated water with a pipe surface temperature of + 115 ° C. The prepared mixture is applied to the surface of the pipe using a roller; the thickness of one coating layer was about 0.4 mm. After a day after applying the first layer (the time required for complete drying of the coating), the next coating layer is applied to the pipe. The number of layers is determined by the operating conditions of the protected surfaces.

Table 1 presents examples of compositions used to obtain anti-icing coatings with anticorrosive and thermal insulation properties.

During the operation of the coating, previously known as anti-corrosion and heat-insulating, at low temperatures and during protection, for example, pipelines, thermal insulation of electric wires - power lines (power lines), a relationship was found between its thermal insulation properties and the formation of ice on their surface. It was found that when this coating is used as an anti-corrosion and heat-insulating coating, the inner surface of the protected products is heated to a temperature exceeding the dew point, as a result of which the formation of ice on the surface of the products coated with such a composition filled with hollow microspheres with different dimensional parameters is prevented. Depending on the type of protected products and their operating conditions, coatings with different thicknesses are applied, which is selected empirically and can, for example, be calculated according to certain methods used in the operation of products at low temperatures. Below, in particular, such a calculation of thermal insulation is given to prevent icing of the protected products.

Table 1 Name of components The content of components in% vol. one 2 3 1. Polymer binder: 20,0 50,0 40,0 - polyvinyl acetate latex 60.0 - 37.0 (50%) - latex dimethyl methacrylate 50,0 - DMMA-1-65-GP - pigments and fillers: - titanium dioxide - 33.0 - - lithopone - - 15.0 - yellow iron oxide pigment - - 2.5 - talc - - 2.5 - a piece of chalk - - - - mummy - - - - thickener (ethyl cellulose) carboxymethyl cellulose - - 3.0 - dispersant (sodium polyphosphate) - 4.0 1,0 - antiseptic (sodium pentachlorophenolate) - - 2.0 - corrosion inhibitor (sodium nitrite) - - 3.0 - coalescing additive - - 1,5 - surfactant (OP-7) 10.0 5,0 5,0 - water 30,0 7.0 27.5 2. A mixture of hollow microspheres: 80.0 50,0 60.0 - a mixture of glass microspheres: - glass microspheres with a size of 35 μm and a density of 650 kg / kg ³ 24.0 - 30,0 - glass microspheres with a size of 100 microns and a density of 150 kg / m ³ 48.0 - - - glass microspheres with a size of 200 microns and a density of 70 kg / m ³ 8.0 - thirty, - a mixture of polymer microspheres: - - polystyrene microspheres with a size of 10 μm and a density of 650 kg / m ³ - 15.0 - - polystyrene microspheres with a size of 500 microns and a density of 50 kg / m ³ - 5,0 - - polystyrene microspheres with a size of 50 microns and a density of 400 kg / m ³ - 30,0 -

table 2 The name of indicators The properties The tensile strength, kgf / cm ² 80.0 Elongation at break,% 5,0 The density in the liquid state, kg / dm ³ 0.50 The density of the finished coating, kg / dm ³ 0.30 Vapor permeability, g / m / hour 50,0 Water permeability, g / m, 24 h less than 30.0 Light reflection,% 82.0 Light scattering,% 92.0 Coefficient of thermal resistance radiation component of thermal conductivity with 2 mm coverage up to 20.0 Thermal conductivity for radiation heat transfer component, V / m · ° С 0.001 Thermal conductivity for contact heat transfer component, V / m · ° С 0,037 Adhesion, kg / cm ² 25.0

Calculation of thermal insulation to prevent icing of power line wires

The methodology for calculating the thickness of heat-insulating equipment operated at low temperatures is based on SNiP 2.04.14-88. The thickness of the insulating coating layer is determined by the formula:

,

,

where δ _k is the thickness of the insulating layer [m]

d is the diameter of the insulated object.

,

,

- соотношение наружного диаметра изоляционного слоя к наружному диаметру изолируемого объекта,Where

- the ratio of the outer diameter of the insulating layer to the outer diameter of the insulated object,

λ _k - thermal conductivity of the insulating layer [W / m · ° C]

- сопротивление теплоотдачи на 1 м длины теплоизоляционной конструкции [Вт/м·°С]

- heat transfer resistance per 1 m of the length of the insulating structure [W / m · ° C]

r _m is the thermal resistance of the non-metallic wall of the cylindrical equipment, in our case r _m = 0

α _e - heat transfer coefficient from the outer surface of the insulation [W / m ² · ° C]

t _w - temperature of equipment, ° С

t _e - ambient temperature, ° С

q _e is the normalized linear heat flux density in 1 m of the length of the cylindrical heat-insulating structure, [W / m]

K = 1 in our case

The initial data for the calculation:

λ _k = 0,037 W / m · ° С

d = 20 mm = 0.02 m

q _e = 3 W / m

α _e = 29 W / m ² · ° C

t _w = 0 ÷ -4 ° C

t _e = 0 ÷ 4 ° C

At t _w -t _e = 1 ° C

=

и

=

and

B = 1,058

At t _w -t = 2 ° C

lnB = 0.23 [0.67-0.09] = 0.13

B = 1.14

δ _k = 0.01 × 0.14 = 0.0014m = 1.4 mm

At t _w -t = 3 ° С

lnB = 0.23 [1-0.09] = 0.21

B = 1.235

δ _k = 0.01 × 0.235 = 0.0023m = 2.3 mm

The condition for the formation of ice on the power lines is the presence of air with high relative humidity - more than 90% and a temperature slightly above 0 degrees and electric wires cooled to freezing temperatures. In order for the process of ice formation to take place, the dew point of the air saturated with moisture should be located about 0 ° C. In this case, the difference in ambient temperature and the surface of the electrical wires is small and reaches several degrees.

The increase in the thickness of the ice will stop as soon as the temperature on the ice surface is equal to the dew point temperature. Thus, by applying 2-3 layers of a liquid-ceramic coating to the electric wires, it is possible to avoid the formation of frost or to significantly reduce the thickness of the frost and to avoid wire breakage.

Claims (1)

The use of an anti-corrosion and heat-insulating coating as a coating that prevents icing of various surfaces operating at low temperatures, and is made of a water-suspension composition with a viscosity of 1 to 100 Pa · s, containing a polymer binder and hollow microspheres, and applied at least in the form of one layer on the surface to be protected, followed by drying of the coating, while the composition as a polymer binder contains an aqueous polymer latex composition containing 10-90 vol. % (co) polymer selected from the group consisting of acrylate homopolymer, styrene-acrylic copolymer, styrene-butadiene copolymer, polystyrene, butadiene polymer, polyvinyl chloride polymer, polyurethane polymer, (co) vinyl acetate polymer or mixtures thereof and from 10 to 90 vol. % of a mixture of water and a surfactant, as hollow microspheres, the composition contains a mixture of hollow microspheres with different sizes from 10 to 500 μm and different bulk density from 650 to 50 kg / m ³ selected from the group comprising hollow glass microspheres, hollow ceramic microspheres, hollow polymer microspheres, technogenic (ash) hollow microspheres or mixtures thereof in the following ratio of components of the water-suspension composition, vol.%:
polymer latex composition 5-95 the above hollow microspheres 5-95