RU2492201C1 - Fire-retardant cold-setting coating composition and method for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to fire-retardant silicone coatings meant for fireproofing cable factories having metal structures, ventilation ducts, including at atomic power plants and thermal power plants, as well as fire-resistant and moisture-protective finishing of industrial and building structures, including at atomic power plants and thermal power plants. The coating is obtained from a surface-bulk cold-setting composition which contains low-molecular weight siloxane rubber, low-molecular weight silanes, dibutyltin diacetate, ammonium polyphosphate and technical pentaerythritol, glased at defined ratios. The composition is prepared by bulk mixing of ingredients and is characterised by that the mixing process is supplemented with forced rubbing of granular ingredients in liquid siloxane rubber in a closed container with working volume ranging from 0.1 to 0.5 m³. Rubbing is carried out between movable blades and fixed legs, wherein the movable blades forcefully inject the composition into a grinding zone, thereby causing heating of the working mixture of the composition.

EFFECT: invention provides efficient fireproofing and corrosion protection of materials.

2 cl, 1 tbl, 3 ex

Description

The invention relates to fire-retardant silicone coatings of intumescent type and is intended, for example, for fire protection of cable facilities, including nuclear power plants and thermal power plants, to increase the fire resistance limit of load-bearing metal structures, to increase the fire resistance limit of ventilation ducts, including nuclear power plants and thermal power plants, and to finish fire-resistant structures industrial and construction facilities, including NPPs and TPPs, in order to increase moisture protection in the SPO-E Systems during transportation and storage.

Known silicone sealant based on dimethylsiloxanes, which are mixed with an inorganic filler, and then with alkylhydro-polysiloxane and a catalyst (a solution of tin diethyl dicaprylate in poethylsiloxane). The specified known composition has a very long crosslinking phase from three to eight hours, as well as high viscosity and cannot be filled without a preliminary solution in gasoline, which is unacceptable for flame retardant sealants used in construction and shipbuilding (see AS SSR No. 456819, Cl C08L 83/04, 1975).

Another casting composition based on low molecular weight siloxane rubber is known, used for sealing electronic and radio engineering devices, creating an electrical insulating layer in electric machines and devices. The composition contains components in the following ratio, parts by weight: siloxane rubber 100; filler in the form of aluminum hydroxide 1-100; the product of the incomplete hydrolysis of tetraethokylamine 0.3-2.0; tin octoate 1.5-4 (see ed. St. USSR No. 730762, Cl. C09K 3/10, 1977),

However, the known composition does not provide the required fire resistance.

To reduce the flammability and fire resistance of the material and structure, paints are widely used. The most effective and promising of them are organic coatings of intumescent (intumescent) type. The intumescent technology of protecting products from the effects of flame has appeared relatively recently and consists in a combination of coke formation and foaming of a paint and varnish protective coating under the influence of high temperatures. The resulting foamed cellular coke layer protects the painted surface from exposure to heat flux or flame.

Fire retardant intumescent paints are quite complex multicomponent systems, since their composition, along with the traditional components of conventional paints, includes intumescent systems that include three main components: coke formation catalyst, coke forming and foaming agents (Vandersall HL Flam. 1971 V.2 April. P.97 -140). Phosphorus-containing compounds and most often ammonium polyphosphate (ACE) are usually used as a catalyst. As a raw material for the formation of the carbon skeleton of the foam layer, as a rule, polyalcohols are used, and as polyphores, organic amines or amides that emit non-combustible gases at elevated temperatures - carbon dioxide, nitrogen, ammonia, and foaming systems. The most popular of the polyalcohols in such formulations is pentaerythritol, and of the amines, melamine.

From RU 2174527, 10.10.2001, a fire-retardant intumescent paint is known containing an aqueous dispersion based on an acrylic dispersion or a mixture thereof with a homo- or copolymer dispersion of vinyl acetate, a mixture of pentaerythritol and ammonium polyphosphate, as well as surfactants, defoamer, ethereal cellulose thickener, preservative additive, titanium dioxide, talc, water. The disadvantage of this paint is that it is used only for internal work due to its low resistance to weathering, i.e. provides the necessary protection against corrosion damage.

So, from RU 2244727, 01/20/2005, fire-retardant intumescent paint is known, including a polymeric binder (polymer aqueous dispersions, for example styrene-acrylic, polyvinyl acetate, butadiene styrene), a solvent, an intumescent additive based on ammonium pententerite and ammonium polyphosphate and expanded graphite. Known paint has increased fire resistance and a wider temperature range of expansion.

However, these paints do not provide the necessary level of heat-shielding properties and corrosion protection.

So, the most effective means of thermal protection in conditions of heat exposure in extreme conditions is the use of intumescent fire retardant materials.

Known intumescent fire retardant composition containing intercalated graphite, perlite, methylphenylsiloxane rubber, methylphenylsiloxane resin, silicosilazane, boron nitride and a solvent system (RU 2190649, 04.10.2000). As a non-metallic substrate (as one of the layers), fabrics, tapes, needle-punched materials, felts, mats made of glass, polymer and carbon fibers are used. These materials are located between the intumescent composition and the protected product. The disadvantage is the low fire resistance of the coating.

Known flame-retardant materials of tape type brand Letsar-ZA (TU 38.403612-89) based on siloxane rubbers. However, this material has a low gasoline and fuel resistance (20% swelling in gasoline), as well as low fire retardant properties. Known intumescent fire retardant material according to US patent No. 383082, CL. 260 2.5S, 1976, including 35-75 parts by weight organosilicon resin, 7-8 wt.h. iron oxide. But this material has a low degree of foaming of -3 and insufficient fire retardant properties.

Silicone rubber compositions, including the composition according to the invention consists of three essential ingredients. These ingredients are (i) a silicone polymer, (ii) one or more fillers (filler), and (iii) a curing agent, sometimes called a crosslinking agent.

Silicone rubber compositions are usually prepared by mixing a substantially linear high molecular weight silicone polymer with a filler and other desirable additives to form a starting or raw material mixture. Before use, the base is mixed with the introduction of a curing agent, other fillers and additives, such as pigments, release agents, plasticizers and adhesion promoters; and it can be vulcanized by vulcanization in the press or continuously by extrusion, that is, injection and transfer formation, to obtain the final product in the form of silicone rubber. For example, cable insulation is extruded using special techniques, in which silicone rubber is applied to cable cores using transverse extrusion heads.

Closest to the claimed invention is a known composition based on low molecular weight siloxane rubber used in construction, shipbuilding and installation of process plants for making fireproof partitions when pipe cables pass through walls and ceilings.

The known composition contains a low molecular weight siloxane rubber, aluminum hydroxide, an organotin catalyst and a low molecular weight silane, silicone oil is additionally introduced, and the composition contains a mixture of polyorganosiloxanes as a siloxane rubber: polymethylsiloxane, polydimethylsiloxane, methyl cyclosiprosiloxane, as a tin oleuto-butanol organo-tin oleuto-butanol-organolate methyltrimethoxysilane and tetraethoxysilane (RU 2221000, 01/10/2004).

This composition does not form an intumescent coating and does not provide the necessary protection, as well as corrosion resistance.

The objective of the claimed invention is to increase fire retardant properties due to the effect of the formation of a vulcanized composition of a vulcanite foam under the influence of an elevated temperature (from 300 ° C), having low thermal conductivity and at the same time providing anti-corrosion protection.

The use of selected catalysts and other additives of a mixed method of vulcanization of the system, in which the composition passes from the pasty phase to the rubbery one from the surface in contact with air over the entire thickness of the layer over a period of 3 to 24 hours in a wide range of ambient temperatures. The effect of mixed vulcanization is achieved by additional introduction of tin dibutyl diacetate into the prepared paste at the stage of final preparation of the composition before its use.

The technical task and the specified technical result is achieved by the claimed group of the invention and the method for its preparation.

So, the technical task is achieved by the fire retardant composition of cold surface-volume curing for coatings, including low molecular weight siloxane rubber, low molecular weight silane, dibutyltin diacetate, in which, as a low molecular weight silane, it contains trisbutanone oxime-methylsilane and additional aminosilane-methyl-iroximethane-trimethanes aminopropyltrimethoxysilane in ethanol ammonium polyphosphate and technical pentaerythritol in the following ratio tion of the starting components in parts by weight:

Low molecular weight siloxane rubber fifty Aminopropyltrimethoxysilane 2-8 Tris-butanonoxime-methylsilane 6-14 Dibutyltin diacetate 2-4 The specified ammonium polyphosphate 100-150 Specified pentoerythritol technical 90-120

The technical task is also achieved by the method of obtaining this flame retardant composition of cold surface-volume curing for coating, which consists in first producing a paste containing low molecular weight siloxane rubber, ammonium polyphosphate and technical perthaerythritol, then preparing a catalytic mixture containing Tris-butanone oxime- methylsilane, aminopropyltrimethoxysilane, dibutyltin diacetate, which are further mixed (paste and catalytic mixture), and the paste is obtained by forcing nogo rubbing bulk ingredients - ammonium polyphosphate and pentaerythritol technical into liquid silicone rubber mixer in a closed vessel with a working volume of 0.1 - 0.5 m ³ between the movable blades and the fixed blades of the mixer, wherein the movable blade is pumped paste obtained in the grinding zone in which the heating and homogenization of the working mixture of the paste.

In the claimed group of the invention, for example, low molecular weight rubber is, for example, siloxane type 6712 Silop rubber. E12, which is a siloxane rubber siloprene, organosilicon rubbers of the type SKTN grades A and G, their mixtures in various ratios.

As technical pentaerythritol, micronized and sizing pentaerythritol with a particle size of, for example, 100 μm, saponified with a solution of γ-aminopropyltrimethoxysilane in ethanol is used.

Microlon 93 type pentaerythritol, for example.

As ammonium polyphosphate (ammonium salt of polyphosphoric acid), for example, micronized with a particle size of 100 μm and a soda solution with γ-aminopropyltrimethoxysilane in ethyl alcohol are used.

Ammonium polyphosphate type Exflam APP221.

The following are specific examples of a flame retardant surface-volume curing composition for a coating based on siloxane rubber, which is intumescent under the influence of fire, and a method for producing it.

These examples illustrate the invention without limiting it.

Example 1. (composition of cold surface-volume curing with a vulcanization time of 24 hours at an ambient temperature of -20 ° C), prepare the composition composition, parts by weight:

Siloxane rubber (6712 Silop. E12) fifty Aminopropyltrimethoxysilane (Silane Z-6011) 2 Tris-butanone oxime-methylxylan (Silane VO Z-9075) 6 Tin Dibutyl Diacetate (6696 Catlyst DBTA) 2 Polyphosphoric Ammonium Salt (Exflam APP 221) one hundred Technical Pentaerythritol (Microlon 93) 90

Example 2. (composition of a cold surface-volume curing with a vulcanization time of 10 hours at an ambient temperature of -20 ° C), prepare a composition of the composition by weight:

Siloxane rubber (6712 Silop. E12) fifty Aminopropyltrimethoxysilane (Silane Z-6011) 5 Tris-butanone oxime-methylxylan (Silane BO Z-9075) 10 Tin Dibutyl Diacetate (6696 Catlyst DBTA) 3 Polyphosphoric Ammonium Salt (Exflam APP 221) 120 Technical Pentaerythritol (Microlon 93) 10

Will 3. (composition of cold surface-volume curing with a vulcanization time of 3 hours at an ambient temperature of -20 ° C), prepare the composition composition, parts by weight:

Siloxane rubber (6712 Silop. E12) fifty Aminopropyltrimethoxysilane (Silane Z-6011) 8 Tris-butanone oxime-methylxylan (Silane VO Z-9075) fourteen Tin Dibutyl Diacetate (6696 Catlyst DBTA) four Polyphosphoric Ammonium Salt (Exflam APP 221) 150 Technical Pentaerythritol (Microlon 93) 120

The method for preparing the composition is carried out by mixing the components and is characterized in that the mixing process is supplemented by the forced rubbing of the loose ingredients into the liquid siloxane rubber in a closed container of the mixer with a working volume of 0.1 to 0.5 m3. Rubbing occurs between the system of movable trapezoidal blades and fixed knives, while the movable blades force the composition into the wedge-shaped area between the blade blades, grinding and homogenizing the mixture, thereby causing the mixture to heat up in both directions of the working mixture in the mixer.

The method for preparing the composition includes the following steps:

1. Preparation of the main paste

Step 1.1 Component loading (≈30 min)

Download is carried out by a sequential quantitative and temporary method in accordance with the selected recipe (Example 1 ÷ 3), ensuring the introduction of a large number of dry bulk components into a viscous polymer medium and a uniform distribution throughout the volume of the mixer. First, in the course of 20-30 minutes, the ammonium salt of polyphosphoric acid and technical pentaerythritol in the required proportion are successively added to the siloxane rubber. This loading method allows you to control the process of fast and high-quality distribution of dry bulk components in liquid viscous components, preventing an avalanche-like increase in the viscosity of the working mixture. After the components are fully loaded, the mixing cycle is carried out.

Stage 1.2. Mixing of components (≈6-7 hours).

Mixing is done according to the cyclic algorithm. The working mixture moves in the forward and reverse direction in the working volume of the mixer. Mixing, homogenization and rubbing of loose components into the liquid occurs within 6-7 hours between the moving blades and the fixed knives. In this case, the moving blades force the mixture into the milling zone. The movement of the mixture in both directions of rotation of the shaft ensures continuity of the working cycle and causes heating of the working mixture of the composition. Cooling of the working mixture is ensured by normalizing the amount of technical water of the cooling system over the entire area of the mixer working volume. The effect of heating the working mixture further homogenizes the composition, and causes a reduction in the preparation time of the final product. Homogeneity and invariance of viscosity indices throughout the product volume is a criterion for the end of mixing.

Stage 1.3. Cooling the finished composition (≈60 min)

Cooling of the finished composition is carried out after stopping the drive of the mixing equipment by supplying a normalized amount of process water to the cooling system over the entire area of the mixer working volume. When the mixture reaches the ambient temperature, the final product is filtered and unloaded.

Stage 1.4. Unloading and filtering the composition (≈60 min)

Unloading and filtration is carried out by a screw pump through a system of pipelines and filters, providing a standardized size of dry particles in the finished product, acceptable for the machine method of applying the finished compound. Unloading is carried out in tare units, after which the product is ready for shipment.

2. Preparation of the catalytic system

Step 2.1. Component loading (≈5 min).

Download is carried out by sequential introduction of a liquid catalyst: tin and silanes dibutyl diacetate aminopropyltrimethoxysilane and tris-butanone oximethylsilane in the reactor working volume. After complete shipment, the mixing cycle is carried out.

Stage 2.2. Mixing of components (≈15 min).

Mixing is performed according to the cyclic algorithm in accordance with the selected recipe (Example 1 ÷ 3). Homogeneity and invariance of viscosity indices throughout the product volume is a criterion for the end of mixing.

Stage 2.3. Unloading and volume dosing of the catalytic system (≈30 min).

Unloading and volumetric dosing sequentially in prepared packaging units, after which the cats product for shipment.

Immediately before use, the obtained base paste based on low molecular weight siloxane rubber is mixed with a catalyst mixture (system).

This composition is both one-pack (in cartridge) and two-pack (paste and catalytic system are in different containers).

The following table presents the properties of the composition and the coating based on it.

Properties of the composition and coatings of the invention.

Table The name of indicators Units rev. Example Properties one 2 3 Properties determined immediately after preparation or at the time of coating. 1 Appearance of the finished coating White / gray material, uniform in color and consistency, without impurities 2 Viscosity cp × 10 ³ 29 ± 4 29 ± 4 29 ± 4 3 Viability h > 1.5 > 1.5 > 1.5 4 stickiness disappearance time h <2-3 <2-3 <2-3 5 The rate of vulcanization (time of formation of a solid surface layer with a thickness of 1-1.5 mm) day <1 <1 <1

Parameters determined after vulcanization of the coating 6 Shore A hardness units ≥30 ≥30 ≥30 7 Conditional tensile strength, not less MPa > 1.3 > 1.3 > 1.3 8 Relative elongation under tension, not less % > 100 > 100 > 100 9 Water absorption, no more % <0.5 <0.5 <0.5 10 Operating temperature ° C -60 ++ 250 11 Electric strength SQ / mm > 10 > 10 > 10 12 Expansion coefficient, not less > 5 > 5 > 5 13 Corrosion to known building materials and metals well no no no no 14 Permissible integral radiation dose, not less than Glad > 1.25 × 10 ⁸ > 1.25 × 10 ⁸ > 1.25 × 10 ⁸ 15 Lifetime years > 40 > 40 > 40

The coating should maintain its technical characteristics during continuous operation in an environment with a humidity of 100% and during emergency conditions in an environment with a gas-vapor mixture.

1.5 The coating is resistant to chemical influences during repeated washing with decontamination solutions:

NaOH - 50 g / l, KMnO ₄ - 3 g / l - alkaline,

H ₂ C ₂ O ₄ - 50 g / l, HNO ₃ - 5 g / l - acidic or

H ₂ C ₂ O ₄ - 30 g / l, H ₂ O ₂ -1 g / l - acid.

The coating is repairable, since previously manufactured material has an affinity for freshly prepared material, which provides for the possibility of restoration under mechanical and other damage.

In case of fire, the coating forms a mechanically strong volcanic foam (expansion effect), which serves to protect the cable economy, supporting metal structures, ventilation ducts (performed by Siloterm-EP6V).

The coating is used in places where excessive swelling during a fire can damage the protected structure and form a mechanically less durable vulcanite foam.

Thus, the invention allows to provide fireproof and anti-corrosion protection of metal structures and cables in the winter.

Claims (2)

1. Fire retardant composition of cold surface-volume curing for coating, including low molecular weight siloxane rubber, low molecular weight silane, dibutyltin diacetate, characterized in that it contains tris-butanone oxime methylsilane and aminopropyltrimethoxysilane-aminopropyltrimethoxysilane and, in addition, contains additional molecular weight silane and additionally ethyl alcohol pentaerythritol technical and ammonium polyphosphate in the following ratio of starting components, wt. .:
Low molecular weight siloxane rubber fifty Aminopropyltrimethoxysilane 2-8 Tris-butanonoxime-methylsilane 6-14 Dibutyltin diacetate 2-4 The specified ammonium polyphosphate 100-150 Specified pentaerythritol technical 90-120 2. A method for producing a fire retardant composition of cold surface-volume curing for a coating according to claim 1, comprising preparing a paste containing low molecular weight siloxane rubber, ammonium polyphosphate and technical pentaerythritol, preparing a catalyst mixture containing tris-butanonoxime-methylsilane, aminopropyltrimethoxysilane, dibutyltin tin-ethyltetisolide mixing the prepared paste and the catalytic mixture, the paste being obtained by forcing the loose ingredients — ammonium polyphosphate and ne technical taerythritol into liquid siloxane rubber in a closed container of the mixer with a working volume of 0.1 to 0.5 m ³ between the moving blades and the fixed knives of the mixer, while the moving blades pump the resulting paste into the grinding zone, where the working mixture is heated and homogenized .