RU2391364C2 - Organosilicon composition for electrically insulating and anticorrosion cold setting coating and method of preparing said composition in aerosol form - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention pertains to cold setting protective coatings for electrically insulating protection of wires, metal structures, metal articles, ceramics and plastic. The proposed organosilicon composition consists of the following (wt %): polymethylphenylsiloxane (15-60) in form of an industrial compound KO-921 or KO-922 or KO-923 or their mixture, fine-grained metal oxides (5-20), solvent (10-30) - toluene or o-xylene and azeotropic extractant (25-50) - tetramethylsilane or a propane-butane mixture. Proposed also is a method of preparing the said composition in form of an aerosol.

EFFECT: design of a composition made from industrial components with easy technical application for making coatings with electrically insulating and anticorrosion properties at temperatures ranging from -70°C to +250°C and having strength and adhesion properties.

2 cl, 2 tbl, 3 ex

Description

The invention relates to the field of protective coatings, in particular, to the production of organosilicon compositions used as heat-resistant coatings for electrical insulation of wires, metal structures, ceramics, metal, plastic, cured in the cold. Such compositions are widely used in various industries and in technology as coatings, gaskets, casting compounds, electrical insulation materials, including those operating under extreme conditions of high and / or low temperatures.

Known polymer composition having dielectric properties (SU No. 1799024, C08L 63/02, publ. 20.12.01). The composition includes an epoxy diane resin, triethanolamine as an amine hardener and a petroleum polymer resin with a softening point of 98-105 ° C with an iodine number of 55-70 g / 100 g, a volatile content of 1.2-1.5 wt.%, Having in its composition copolymerization products mainly, wt.%: isoprene 16-22, piperylene 12-18, dicyclopentadiene 34-43, indene 18-25, unidentified hydrocarbons 4-6, in the following ratio of components, wt.%: epoxy resin 60-80, triethanolamine 10-15, petroleum resin 5-30.

In the known composition, epoxy diane resin, which is a toxic substance, is used as one of the main components. In addition, directly when applying the composition to the substrate, it is necessary to mix the resins and introduce a hardener, which makes it difficult to use.

Known composition for anti-corrosion coating (RU No. 2041906, C09D 183/08, 5/08, publ. 08.20.95). The composition includes chlorinated polymethylphenylsiloxane with a chlorine content of 2.3-8 wt.%, Fillers - Muscovite mica, titanium dioxide and aerosil, and an organic solvent - toluene, in the following ratio, wt.%: Chlorinated polymethylphenylsiloxane 29-35, mica Muscovite 20-25, titanium dioxide 1-5, aerosil 1-5, organic solvent (toluene) 40-47.

The use of the known composition for anticorrosion coating provides a sufficiently high heat resistance (up to 430 ° C) and fairly good electrical insulation properties of the resulting coatings. One of the main components of the composition is chlorinated polymethylphenylsiloxane obtained by chlorination of K-40 industrial resin with molecular chlorine; to obtain it, an additional chemical reaction, scarce additives, additional equipment are necessary, in addition, chlorine is a toxic substance that is harmful to health.

A known composition for a protective coating (RF patent No. 2041905, class C09D 183/04, 5/08, 7/14, prior. 18.10.93, publ. 20.08.95). The composition includes polymethylphenylsiloxane, toluene, tetrabutoxytitanium, silicate, metal oxides and silicon carbide as a filler in the following ratio of components, wt.%: Polymethylphenylsiloxane 25-34, tetrabutoxytitanium 5-11, silicate 42-60, metal oxides 1-5, silicon carbide (filler) 3-10, toluene - the rest. The protective coatings obtained by applying the known composition to the substrate have low electrical insulating properties when exposed to high temperatures (more than 200 ° C).

Known silicone composition for cold curing (RU No. 2231532, C08L 83/04, C09K 5/10, C09K 5/00, publ. 2004.06.27). It contains a linear ladder block copolymer of the general formula

(where y = 205-250) ....... 100 parts by weight,

inorganic filler — silicon or aluminum oxides and / or aluminosilicate fibers 1-26.5 parts by weight, structuring agent — tetraethoxysilane or products of its partial hydrolysis 0–9 parts by weight, curing catalyst — tin dibutyl dilaurate, γ-aminopropyltriethoxysilane or vinyl tris (acetoxyximoxy) silane is 1-20 parts by weight and an additional heat stabilizing agent is introduced — iron, nickel phosphides, iron, copper, cerium oxides or a mixture thereof, applied as an active phase to metals or metal oxides selected from the group of aluminum, iron and titanium, 3-10.6 parts by weight

The composition is prepared by mixing the components in a paddle mixer until a homogeneous mixture is obtained, after which a structuring agent and catalyst are added to it in the required amount. The mixture is cured at ambient temperature until an elastic rubber-like material is formed within 1-3 days.

The disadvantage of this invention is the presence of a curing catalyst and a significant amount of time required to obtain a rubber-like material, namely 1-3 days.

A known composition for a protective coating based on polymethylthenylsiloxanes having electrical insulation properties and not having a curing catalyst (RU No. 2226539, C09D 183/04, publ. 2004.04.10).

The composition includes the following components.

The first component - polymethylphenylsiloxane, which is part of the composition in an amount of 15-60 wt.%, Plays the role of a base, a film-forming component. When using this component in smaller amounts, a significant decrease in the adhesion of the coating to the substrate is observed, the coating becomes brittle, its protective properties deteriorate, and when using excessive amounts, the heat resistance of the resulting coatings worsens, cracks may occur when the temperature changes from -60 to + 500 ° C.

The second component of the composition - metal oxides, which are part of the composition in an amount of 3-20 wt.%, Contribute to the formation of a durable film on the coating surface. As metal oxides, in particular, oxides of chromium, cobalt, copper, titanium and zinc can be used. When this component is introduced in a smaller amount, the protective properties of the coating deteriorate, its strength deteriorates, and when it is introduced in excessive amounts, the adhesion of the coating to the substrate deteriorates.

The third component of the composition is silicate (mica), which in combination with talc or asbestos helps to increase the heat resistance of the resulting coatings and their electrical insulating properties.

The composition for a protective coating was made as follows.

Uralitic balls were loaded into a ball mill with a volume of 5 m ³ (it is possible to use a mill with a volume of 1.63 to 8 m ³ ). After that, all the dry components of the composition were loaded into the mill, and then polymethylphenylsiloxane and toluene, the ratio of the components was selected depending on the example. Within 24 hours, using the uralitic balls, the components were milled, as a result of which the components were mixed, a mechanochemical reaction took place between them. The result is a composition in the form of a suspension.

When testing the composition for compliance with the regulatory document, it was applied to the surface of the sample by various methods: dipping, paint rollers, etc. After applying to the sample, the coating was dried at a temperature of 200 ° C for 3 hours.

This technical solution is made as a prototype for the claimed method and composition of the present invention.

The disadvantage of the prototype is the long drying time, namely 3 hours, and a high exposure temperature, namely 200 ° C.

The objective of the proposed invention is to develop a composition using industrial components with a simple technology of application and cold-cured to obtain materials with electrical insulating and anti-corrosion properties, operable at temperatures from -70 ° C to + 250 ° C and with strength and adhesive properties.

The technical result achieved in this case is to improve the technical and operational properties by providing curing in the cold in a short time and preserving these properties for a long time at temperatures up to 250 ° C.

The specified technical result is achieved in that the composition for electrical insulating and anti-corrosion coatings of cold curing includes toluene or orthoxylene, metal oxides, contains industrially produced polymethylphenylsiloxanes of the grades KO-921, KO-922, KO-923, as well as an azeotropic displacer, which is used as a tetramethylsilane or a propane-butane mixture.

The specified technical result is also achieved by the fact that in the method for manufacturing an organosilicon composition of an electrical insulating and anti-corrosion coating of cold curing in an aerosol version, which consists in mixing the components for 15 minutes until a homogeneous mixture is obtained at room temperature, namely polymethylphenylsiloxane in the form of an industrial compound of the brand KO- 921 or KO-922 or KO-923, fine metal oxides, toluene or o-xylene, and the resulting homogeneous mixture is placed in an aerosol container a can with a metal ball inside to mix the composition; the can is filled with an azeotropic displacer such as tetramethylsilane or a propane-butane mixture in an amount of 25-50% of the total amount of a homogeneous mixture.

These features are significant and are interconnected with the formation of a stable set of essential features sufficient to obtain the desired technical result.

According to the present invention, an organosilicon composition of an electrically insulating and anticorrosive coating of cold curing based on polymethylphenylsiloxane, metal oxides and a solvent and an azeotropic displacer is considered, while the industrial compound of the grades KO-921, or KO-922, or KO-923, or mixtures thereof, is used toluene or o-xylene is used as a solvent, and tetramethylsilane or a mixture of propane-butane in an amount of 25-50% by volume are used as an azeotropic displacer total amount of a homogeneous mixture of the remaining components.

The first component - polymethylphenylsiloxane is used in the form of industrially produced compounds under the brands KO-921, KO-922, KO-923. These compounds are obtained by hydrolytic co-condensation of phenyltrichlorosilane and dimethyldichlorosilane with subsequent polymerization and are polymers with different molecular chains and different contents of active chemical groups in their composition. Compounds are included in the composition in an amount of 15-60 wt.%, Play the role of a base, a film-forming component. When using them in smaller amounts, a decrease in the adhesion of the coating to the substrate is observed, and when using overestimated amounts, the mechanical properties of the resulting film deteriorate in the temperature range from -70 ° C to + 250 ° C.

The second component of the composition - metal oxides, which are part of the composition in an amount of 5-20 wt.%, Contribute to the formation of a durable film on the coating surface. As metal oxides, in particular, oxides of chromium, cobalt, copper, titanium and zinc can be used. When this component is introduced in a smaller amount, the protective properties of the coating deteriorate, its strength deteriorates, and when it is introduced in excessive amounts, the adhesion of the coating to the substrate deteriorates, the composition becomes non-plastic.

The third component, a toluene or orthoxylene solvent, is used in an amount of 10-30% to adjust the viscosity of the working solution.

The fourth component, an azeotropic displacer tetramethylsilane or a propane-butane mixture, is used to accelerate the curing of the composition in the cold due to azeotropic distillation of the solvent and high-boiling components of industrial compounds KO-921, KO-922, KO-923, resulting in an increase in the rate of film formation. Used in amounts of 25-50%. When used in smaller quantities, the drying time of the composition significantly increases. When used in large quantities, an insufficiently strong film is formed that has low adhesion and low electrical insulation properties.

The composition is prepared by mixing the components in a paddle mixer until a homogeneous mixture is obtained, then place it in an aerosol can, which is filled with tetramethylsilane or a propane-butane mixture containing an intrametallic ball. After vigorous shaking for 10-15 seconds, the mixture is sprayed onto the surface to be treated at ambient temperature. After 15-20 minutes, the composition dries and acquires target characteristics in terms of electrical insulating and anticorrosive properties.

The experimental results are illustrated by examples.

Example No. 1

In a two-necked flask with a paddle stirrer, 30 g of polymethylphenylsiloxane (KO-921 compound), 60 g of toluene, 10 g of finely dispersed copper oxide are placed and stirred at room temperature until smooth for 15 minutes. Then the resulting mass is placed in an aerosol can with a metal ball inside with a capacity of 500 ml and using a valve, fill it with 100 g of a mixture of propane-butane. After vigorously shaking the can for 10-15 seconds, spray the composition onto the surface of the material being processed. It is kept at ambient temperature for 15 minutes.

Example No. 2

In a two-necked flask with a paddle stirrer, 120 g of polymethylphenylsiloxane (KO-922 compound) 120 g, toluene 20 g, finely divided chromium oxide are placed 10 g and stirred at room temperature until smooth for 15 minutes. Then the resulting mass is placed in an aerosol can with a metal ball inside with a capacity of 500 ml and using a valve, fill it with 50 g of a mixture of propane-butane. After vigorously shaking the can for 10-15 seconds, spray the composition onto the surface of the material being processed. It is kept at ambient temperature for 15 minutes.

Example No. 3

In a two-necked flask with a paddle stirrer, put polymethylphenylsiloxane (KO-923 compound) 80 g, orthoxylene 20 g, finely divided zinc oxide 40 g and stirred at room temperature until smooth for 15 minutes. Then the resulting mass is placed in an aerosol can with a metal ball inside with a capacity of 500 ml and using a valve, fill it with 100 g of a mixture of propane-butane. After vigorously shaking the can for 10-15 seconds, spray the composition onto the surface of the material being processed. It is kept at ambient temperature for 15 minutes.

Examples for the use of mixtures of compounds of the grades KO-921, KO-922, KO-923 are not presented due to the fact that they repeat examples No. 1, 2 or 3.

The study was carried out in laboratory conditions. The experimental results and compositions are shown in tables No. 1 and No. 2

Table number 1 The composition (% wt.) Component (wt.%) I II III IV V VI Compound KO-921 fifteen 60 40 - - - Compound KO-922 - - - 25 - 45 Compound KO-923 - - - - 35 - Metal oxide 5 5 twenty 10 fifteen fifteen Toluene thirty - 10 25 - - Orthoxylene - 10 - - twenty fifteen Propane-butane mixture fifty 25 fifty - - - Tetramethylsilane - - - 40 thirty 25

Table number 2 Physical characteristics of the compositions Name of characteristic I II III IV V VI Volume resistivity, Ohm · mm 1 · 10 ¹⁰ 1 · 10 ¹² 1 · 10 ¹⁰ 1 · 10 ¹⁰ 1 · 10 ¹⁰ 1 · 10 ¹¹ Dielectric strength, MV · mm 40 70 40 40 40 fifty The dielectric constant four 3 four four four 3 Adhesion, Din / mm ² 17 26 19 fifteen fourteen twenty

The present invention is industrially applicable, can be manufactured using industrially produced inexpensive components.

Claims (2)

1. The organosilicon composition of the electrically insulating and anticorrosive coating of cold curing, made on the basis of polymethylphenylsiloxane, finely dispersed metal oxides and solvent, characterized in that the industrial compound of the brand KO-921, or KO-922, or KO-923, or a mixture thereof, is used as polymethylphenylsiloxane , toluene or o-xylene is used as a solvent, and in addition, tetramethylsilane or a propane-butane mixture in the following ratio of components is used as an azeotropic displacer wt.%:
polymethylphenylsiloxane 15-60 metal oxides 5-20 solvent 10-30 azeotropic displacer 25-50 2. A method of manufacturing an organosilicon composition of an electrical insulating and anti-corrosion coating of cold curing according to claim 1 in an aerosol version, which consists in mixing the components to obtain a homogeneous mixture, characterized in that polymethylphenylsiloxane is mixed for 15 minutes in the form of an industrial compound of the brand KO-921 or KO-922 or KO-923, finely dispersed metal oxide, toluene or o-xylene, and the resulting homogeneous mixture is placed in an aerosol can with a metal ball inside For mixing a composition which is filled with an azeotropic displacer such as tetramethylsilane or a propane-butane mixture in an amount of 25-50% of the total amount of a homogeneous mixture.