RU2185408C2 - Fire-retardant composition for metal structure coatings - Google Patents

Abstract

FIELD: fire protection. SUBSTANCE: invention relates to manufacture of fire-retardant coatings based on polymeric binder and can find use in shipbuilding, oil-and- gas production platforms, and transport. Composition contains perchlorovinyl resin, solvent, and condensation product prepared from, wt. pts: formaldehyde, 16-18; dicyanodiamide, 18-20; sorbitol, 8-10; and oxalic acid, 0.5-1.5. Coating exhibits high fire-retardant properties due to formation of heat-insulation foamed layer when affected by fire or heat at temperature above 140 C on protected surface. Coating is designed to protect metals, wood, cables, etc. EFFECT: improved workability when applying on surface and enabled operation at low temperatures and high humidity. 1 tbl

Description

 The invention relates to the field of production of fire retardant coatings, in particular, coatings based on a polymeric binder having high heat-insulating properties under the action of high temperatures.

 Known fire retardant composition containing melamine-formaldehyde resin, urea-formaldehyde resin, butyl alcohol, hardeners and fillers (ed. Certificate. 452224, CL 09 D 5/18, 1972). This composition has high foaming and heat-insulating properties, but when stored in finished form, it is not viable enough.

 Also known fire retardant foaming composition for the protection of load-bearing metal structures, fire walls, fuel tanks (ed. Certificate. 709654, CL 09 D 5/18, 1980). This composition has good foaming and operational properties, but its heat-insulating characteristics are not high enough.

 Closest to the proposed invention (prototype) is a fire retardant composition for coating metal structures according to the patent of Russia 1804082 (CL 09 D 5/18, 1995). The composition of the prototype consists of the following components in ratios, parts by weight: chlorosulfonated polyethylene - 16-20; toluene - 80-84; magnesium oxide - 2.5-3.0; sucrose - 10-12; ammophos - 40-50; dicyandiamide - 20-30; pentaerythritol - 30-40; urea - 10-12; aqueous sodium tetraborate - 10-15; foamed perlite - 4.5-5.0; Aerosil - 2.5-3.0.

This composition also does not have effective fire protection, since the heating time of the metal substrate to 500 ^o With an initial coating thickness of 2 mm was 0.5 h, which in fire conditions does not protect steel structures from fire, resulting in a quick loss of them structural strength. In addition, the low thermal stability of the resulting carbon layer leads to rapid burnout of the coating. The disadvantages of this composition include the fact that it is possible to apply the coating only with a spatula, which reduces the quality of the coating and increases the consumption of material, as evidenced by the results of tests carried out according to the “Instructions for determining the insulating properties of intumescent coatings for metal” (M. : VNIIPO, 1980).

 When creating a fire-retardant composition, which is the subject of the invention, the task was to increase the fire-retardant properties of the coatings and expand the range of polymer composite materials to protect metal structures.

Improving fire retardant properties is achieved by a composition including:
perchlorovinyl resin, for example PSX-LN - 15 parts by weight;
solvent, for example solvent R-4 - 85 parts by weight;
the product obtained by condensation by mixing formaldehyde, dicyandiamide, sorbitol and oxalic acid - 60-75 parts by weight;
monosubstituted ammonium phosphate - 25-35 parts by weight;
titanium dioxide - 5-10 parts by weight;
Aerosil - 0.5-1.5 parts by weight

Condensation of the product is as follows. In an aqueous solution of formaldehyde (38-40%) 16-18 wt.h. add 0.3 wt.h. potassium hydroxide and 18-20 wt.h. dicyandiamide. The mixture is kept at 50-60 ^o C for 2.5-3 hours, constantly stirring. Then, 8-10 parts by weight are added to the solution. sorbitol and continue the condensation process with stirring, maintaining a temperature of 90-95 ^o With another 2 hours. After this time, 0.5-1.0 wt. including oxalic acid. As the solution cools, the condensation product precipitates, the precipitate is dried and incubated for 4-5 hours at a temperature of 115-125 ^o C. The dried product is crushed in a ball mill to a particle diameter of not more than 70 microns. Then finely ground dry components are mixed with a solution of perchlorovinyl resin in a solvent P-4 - toluene-acetone-ethyl acetate.

 The resulting composition is applied to metal samples using a brush, roller, or by spraying with a layer thickness of 1.1-1.2 mm. Samples coated on them are dried in air for 6-7 days under normal conditions.

Example
To obtain the proposed flame retardant polymer composition 70 wt.h. the condensation product of formaldehyde, dicyandiamide, sorbitol and oxalic acid, 30 wt.h. ammonium phosphate monosubstituted, 8 parts by weight titanium dioxide and 0.5 parts by weight Aerosil is ground in a ball mill to a particle size of not more than 70 microns and mixed with 15 wt.h. perchlorovinyl resin, previously dissolved in 85 wt.h. solvent P-4. Thoroughly mix the composition and apply it to a steel plate.

With a coating thickness of 1.2 mm, it increases in volume during fire tests by 20 times, and the temperature of the metal plate rises to 220 ^o C after 0.5 hours

Tests to evaluate the fire-retardant efficiency of coatings deposited on steel plates with a thickness of 3 mm were carried out under the influence of radiated heat flux in two modes:
1) in the temperature regime of the "standard fire" (GOST 30247.0);
2) under the action of a heat flux with a density of 40 W / cm ² .

The test results were evaluated in the first case by the time of heating the metal plates to 220 ^o C, and in the second - by the temperature of the metal plates 15 minutes after the start of the test. The test results are shown in the table. The table shows that the ratio of the components determines the effectiveness of fire protection. When the content of the components is below the lower limit, the effectiveness of fire protection decreases significantly. When the concentration of ingredients is above the upper limit, the effectiveness of fire protection does not increase, but the viscosity of the composition sharply increases, which creates technological difficulties in applying coatings and leads to a deterioration in the physicomechanical properties of the coating.

 The use of a composition containing components in optimal proportions as a coating provides an increase in fire resistance of metal structures by 30% while reducing the thickness of the initial coating by 1.5 times compared to the prototype.

The main physical and mechanical properties of the coating obtained by using a mixture of components in optimal concentrations are as follows: film elasticity in bending not more than 10 mm (GOST 6806), film strength upon impact not less than 30 cm (GOST 4765), drying time to degree 3 at 20 ⁺ 2 ^o C no more than 3 hours (GOST 19007), adhesion to steel and aluminum no more than 2 points (GOST 15140).

 The data obtained as a result of sanitary-chemical tests (GOST 12.1-005-88, GOST - 12.1.016-79, RD - 52.04-186-89) showed that this coating can be used in closed inhabited premises.

 The coating retains its fire retardant properties with an increase in external pressure up to 500 kPa and with an increase in oxygen concentration up to 25 vol.%.

Claims (1)

Fire-retardant composition for coating metal structures, including a polymeric binder, a foaming filler and a pigment, characterized in that it contains a solution of perchlorovinyl resin as a polymeric binder, and the product of the condensation of formaldehyde, dicyandiamide, sorbitol and oxalic acid in the following ratio of components wt. hours:
Perchlorovinyl Resin - 15
Solvent - 85
Condensation Product, - 60 - 75
derived from
formaldehyde - 16 - 18
dicyandiamide - 18 - 20
sorbitol - 8 - 10
oxalic acid - 0.5 - 1.5
Ammonium phosphate monosubstituted - 25 - 35
Titanium Dioxide - 5 - 10
Aerosil - 0.5 - 1.5

Images