Guangzhou Steel remind you: Fire principle of fireproof coatings and problems
Steel as the main form of modern architecture, at room temperature with a light weight, high strength, good seismic features, short construction period, building high degree of industrialization, large utilization of space, etc., but steel construction characteristics of poor anti-fire function also very obvious. Although steel is a non-combustible material, but it is an excellent heat conduction carriers. Steels at temperatures beyond 300 degrees after the yield point and ultimate strength decreased significantly, reaching 600 degrees intensity is almost zero. Science experiments and examples show that unprotected steel in case of fire, just 15 minutes, the temperature will rise to over itself 540 degrees, resulting in distortion component itself, leading to the destruction of the buildings collapsed, deformed steel use can not be repaired. Therefore, the steel must take fire protection measures. Fireproof protective measures varied, such as the choice of insulation, refractory materials blocking the direct flame burning steel, reduce the speed of heat transfer postpone steel temperature, strength becomes weak time.
Fire approaches the main steel structure coating protection, fire protection board, concrete protection, flexible membrane protection, inorganic fiber protection, within the structure of water cooling protection. Among them, brushing fire retardant coating to facilitate the construction, light weight, low cost, component geometry without limitation, the use of a wide scale, the highest efficiency. Guangzhou Steel
Fireproof coating that is applied to the surface of buildings and structures of steel, fire-resistant insulation protection layer can be formed in order to improve the fire resistance of the steel structure of the coating, the principle is the choice of insulation or heat barrier material direct flame burning steel, slow transfer of heat to the steel, steel postpone temperature rise and weakening of the time. Now, at home and abroad fireproof coatings mainly by matrix resin, catalyst, into carbon agents, blowing agents and other components.
Matrix resin compatible with the other ingredients, both to ensure the paint under normal conditions with a variety of application functions, but also has a flame resistance and excellent foaming swell function in the flame burning or high temperature conditions. Typically, the higher the quality of the acrylic resin carbonized layer fire retardant coating, it is usually used an acrylic resin as the main film-forming material, and it was modified in order to enhance the whole effect of the coating.
A catalyst is a substance that breaks down the acid under certain conditions, the decomposition of the phosphate polyol dehydration, so make it a non-flammable carbonized layer three-dimensional structure. Generally, the more water-soluble melamine phosphate Hangout ammonium phosphate, and both catalytic and foaming double effect, now the main choice of melamine phosphate as catalyst.
A carbon additive is non-flammable material basis of the three dimensional structure of the foam carbide layer coating is formed at high temperatures, charring layer of foam from the skeleton. A carbon agent on the decomposition temperature and the catalyst for a match on the use of high thermal stability containing a carbon-carbon polyol made with poly phosphate agent was elected amine catalyst, such as pentaerythritol, di-amyl alcohol ultra-thin fireproof coatings season Guangdong Daya Bay Nuclear Power Plant for the bare frame houses reached than 10 years ago, can still be used normally. But its drawback is the construction smell great, coating easy to aging, starch. The use made of the carbon agent starch, water resistance of the coating is not easy to solve the problem, but because of its price dipentaerythritol reason, rarely use in the country, and now the country generally choose pentaerythritol as fire retardant coating to carbon agent.
Expansion of large fire-resistant coating only in the role of a foaming agent to the onset of swelling layer at a high temperature flame. In case of fire foaming agent decompose and release ammonia, water, carbon dioxide, hydrogen halide nonflammable gas, the coating in the case reaches the softening point of foaming swell, forming sponge-like structure. Guangzhou Steel
But now there are also fire retardant coating technical problems. The first is the durability. Due to the presence of thick fireproof coating since the major decorative poor, it can only be used in certain of the appearance of the less demanding outdoor steel structures. Widely used is thin and ultra-thin fireproof coatings, particularly ultra-thin. This main raw material by the use of two types of coating ammonium polyphosphate, melamine and pentaerythritol are poor water resistance, there is a follow environment, time dissolution, decomposition, degradation and other issues of aging, therefore, such coatings must be as time goes on fire safety features decline, but not yet to figure out a way to assess the durability of fire retardant coating. Fire Resistance of test reports are given in the paint coating maintenance test results after 1-2 months, but the onset of the fire is unpredictable, fire could be in one year after the paint coating may also be applied after 10 years attack, so expansion is the most important large-scale fire-resistant coating durability.
Followed by security issues. Now the expansion of large steel structure fire in a fire may release ammonia, HCN, hydrogen halide, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide, chlorine, bromine and other poisonous gases. If the concentration of these gases endure beyond the limits of the human body, they will not escape the fire on the officers and firefighters harm.
Production and construction of fireproof coatings are also some problems. Most domestic steel structure fire paint manufacturing company is small, the production process automation level is not high, some companies still in the hands of the workshop type in operation, many products of similar formulation process, dedicated to fire-resistant coating materials research is not enough , detection of raw materials, insufficient control, failure detection means of the production process, improve the construction equipment to be improved, and the rust of not supporting a rigorous test.
In addition, fireproof coatings of test methods, test standards and testing standards difference member and member of the actual project, there are some practical problems, such as how to use the steel components between standard profiles for conversion, how to determine the practical application of the coating thickness steel member countries do not have provisions. Guangzhou Steel
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