Development trend and function of the hottest fire

2022-08-15
  • Detail

In view of the fact that steel structures are widely used in construction projects in recent years, combined with the characteristics and hazards of fire risk, this paper discusses the performance and applicability of several fire-proof coatings, and points out the development direction of fire-proof coatings

0 introduction

building fire protection is an important field of fire science and technology, and fire retardant coating is an important part of fire-proof building materials. Fire retardant coating refers to a kind of coating applied on the surface of the object, which can prevent fire, prevent the spread of fire or isolate the fire source, prolong the ignition time of the substrate or increase the thermal insulation performance to delay the time of structural damage. According to the different uses and objects of use, it can be divided into: decorative fire retardant coating, cable fire retardant coating, steel structure fire retardant coating, prestressed concrete floor fire retardant coating, etc. The development of fire retardant coatings in China is 15 ~ 20 years later than that in foreign industrial developed countries. Although it started late, it developed rapidly. In particular, the fire-proof coating for steel structures has approached or reached the international advanced level in terms of variety, type, technical performance, application effect and degree of standardization. In recent years, its demand has doubled, which is inseparable from the rapid development of steel structure buildings

As a form of high-rise building structure, steel structure has been widely used in the construction industry, especially in super high-rise and long-span buildings, because of its high strength, light weight, good extensibility, seismic resistance and short construction period. By the end of 1990, steel structures accounted for 79% of the 100 super high-rise buildings with a height of more than 200 m in the world. Since the reform and opening up, with the strengthening of international technical exchange and cooperation, the application technology of steel structure has been booming in China, and high-rise and super high-rise buildings have increased rapidly. According to the statistics in 1995, steel structures accounted for 37% of the 100 super high-rise buildings built in China, most of which were built in recent years. With the development of urban scale in our country, the application of steel structure in the construction industry in our country has a very broad prospect. However, because the steel structure itself is non combustible, the problem of fire and heat insulation protection of steel structure has once been ignored. According to the relevant data reports at home and abroad and the tests and statistics of relevant institutions, the fire resistance of steel structure buildings is worse than that of masonry and reinforced concrete structures. The mechanical strength of steel decreases with the increase of temperature. At about 5000 ℃, its strength decreases to 40% - 50%. The mechanical properties of steel, such as yield point, compressive strength, elastic modulus and load capacity, decrease rapidly, and soon lose the support capacity, leading to the collapse of buildings. Therefore, it is imperative to protect the steel structure. The steel structure fireproof coating is brushed or sprayed on the surface of the steel structure, which plays the role of fire prevention and heat insulation, preventing the steel from rapidly heating up in the fire and reducing the strength, and avoiding the collapse of the building caused by the loss of support capacity of the steel structure. As early as the 1970s, foreign countries have carried out active work on the research and application of fire retardant coatings for steel structures and made good achievements, which is still in the ascendant. In the early 1980s, foreign fire-proof coatings for steel structures entered the Chinese market and were applied in engineering. Since the early 1980s, China has also begun to develop fire-proof coatings for steel structures. So far, many excellent varieties have been widely used in all walks of life

2 thick coated steel structure fire retardant coating

thick coated steel structure fire retardant coating refers to the coating thickness of 8 ~ 50m. If the sample is a single 1m of coating, the fire resistance limit of this kind of fire retardant coating can reach 0 5 ~ 3h 。 In case of fire, the coating does not expand, which depends on the non flammability, low thermal conductivity of the material or the heat absorption of the material in the coating to delay the temperature rise of steel and protect steel parts. This kind of fire retardant coating for steel structure adopts appropriate binder, together with inorganic light materials and reinforcing materials. Compared with other types of fire retardant coatings for steel structures, in addition to having some advantages of water-soluble fire retardant coatings, it is low cost because it is inorganic from the base material to most additives. This kind of fireproof coating for steel structures is generally sprayed, and it is mostly applied to indoor steel structures with a fire resistance limit of more than 2 hours. However, due to the thick coating, the appearance and decoration of these products are relatively poor

3 thin coated steel structure fire retardant coating

steel structure fire retardant coating with a coating thickness of 3 ~ 7 mm is called thin coated steel structure fire retardant coating. This kind of coating can expand and foam when exposed to fire. The fire-resistant insulation layer formed by expansion and foam can delay the temperature rise of steel and protect steel components. This kind of steel structure coating is generally polymerized with appropriate latex__ The compound is used as the base material, combined with flame retardants, additives, etc. For this kind of fire retardant coating, it is required that the selected lotion polymer must have good adhesion, durability and water resistance to the steel substrate. Lotion polymers commonly used as the base material of this kind of fire retardant coatings include styrene modified acrylic lotion, polyvinyl acetate lotion, vinylidene chloride lotion, etc. For water-based lotion based fire-retardant coatings, fire-retardant additives, pigments and fillers are dispersed into water, so water actually acts as a dispersion carrier. In order to better disperse various granular additives, dispersants, such as commonly used sodium hexametaphosphate, are also added. The production process of this kind of steel structure fire retardant coating is generally divided into three steps: the first step is to disperse various flame retardant additives in water, and then grind them into slurry with specified fineness; The second step is to prepare paint with base material (lotion); The third step is to mix the slurry with inorganic light materials and reinforcing materials. The coating is generally divided into the bottom layer (thermal insulation layer) and the surface layer (decorative layer). Its decorative property is better than that of the thick coating type. It is sprayed in construction. It is generally used on building steel structures with fire resistance requirements of no more than 2 hours

4 ultra thin steel structure fire retardant coating

various fiber materials are required in the production process of ultra-thin steel structure. Structural fire retardant coating refers to the steel structure fire retardant coating with a coating thickness of no more than 3 mm. This kind of fire retardant coating expands and foams when exposed to fire, forming a dense fire insulation layer. It is a product developed in recent years, and its sales volume will rapidly expand. It can be sprayed, brushed or roller coated, and is generally used on building steel structures requiring a fire endurance of less than 2 hours. Compared with thick coating and thin coating fire retardant coatings for steel structures, Ultra-thin Intumescent Fire Retardant Coatings for steel structures have finer viscosity, thinner coating, convenient construction and better decoration. It can not only meet the fire protection requirements, but also meet the high decorative requirements, especially for exposed steel structures. This kind of coating is currently favored by users. The "SCB" (solvent based) and "SCA" (water-based) Ultra-thin Intumescent Fire Retardant Coatings for steel structures developed by the Fire Research Institute of the Ministry of public security have a coating thickness of 2 69 mm and 1.6mm, with fire endurance of 147 min and 63 min respectively; "LF" (solvent type) and "L6" (solvent type) ultra thin steel structure fire retardant coatings, the coating thickness is 2 mm and 3 mm respectively, and the fire resistance limit is 94 min and 90 min respectively; The "watt base" 38320 type steel structure fire retardant coating (water-based) of Herberts, Germany, has a coating thickness of 2 63 mm, and the fire resistance limit is 63min; 38091 type fireproof coating for steel structure (solvent type), with coating thickness of 2 42 mm, with a fire endurance of 124 min; British "nulfire" fire retardant coating for steel structures (solvent type), with a coating thickness of 2.24 mm and a fire resistance time of 106 min; The "SF" (solvent based) and "ECB" (water-based) ultra-thin fireproof coatings for steel structures made by Jiangsu Lanling company have a coating thickness of 2 07 mm and 1 6 mm, with fire endurance of 150 min and 44min respectively. In a word, because the domestic research on ultra-thin steel structure fire retardant coating is still relatively short, although the research on the fire resistance and physical and chemical properties of the coating film has made rapid progress, it is necessary to further study its weather resistance in order to propose an ultra-thin steel structure fire retardant coating with excellent effect suitable for outdoor application. Foreign fire-proof coatings for steel structures have developed towards ultra-thin, ultra weatherability and excellent decorative performance. The weatherability test has been carried out with reference to the European aging test standard method. The weatherability is excellent, and the weatherability of its coating film meets the requirements of outdoor use. Therefore, in order to catch up with or surpass similar foreign products and meet the needs of the market, the research and development of outdoor ultra-thin steel structure fire retardant coatings with high weather resistance is the future development direction

5 decorative fire retardant coating

in addition to steel structure fire retardant coating, decorative fire retardant coating and cable fire retardant coating are also developing rapidly. Decorative fire-proof coating is a new type of coating integrating decoration and fire prevention. When it is applied on combustible substrate, it can play a certain decorative role at ordinary times; Once a fire occurs, it can prevent the spread of the fire, so as to protect the combustible substrate. It is precisely because of its special use that foreign industrial developed countries appeared fire retardant coatings as early as the 1920s. The development of this coating has gone through two stages. At the initial stage, inorganic fire-proof coatings with silicate salt water glass as binder appear. Such fire-proof coatings do not burn themselves, and can form hollow bubble layer in case of fire, which has a certain protective effect on combustible substrate. The disadvantage is that the thermal insulation performance and weather resistance are poor, and it is easy to whiten, crack and fall off. In the late 1940s, people began to develop organic intumescent fire retardant coatings. The main characteristics of this coating are that its fire resistance and physical and chemical properties are better than inorganic fire retardant coatings. When the coating meets fire, it can form a dense spongy expansion foam layer with good heat insulation performance, which can more effectively protect combustible substrates. Compared with inorganic fire retardant coating, organic intumescent fire retardant coating is a more promising type of fire retardant coating, so it has developed rapidly in the next few decades. By the end of 1970s, the annual sales volume of intumescent fire retardant coating abroad had been more than 7380 tons

the development of decorative fire retardant coatings in China is also divided into two stages. The fire-proof coating appeared in the late 1950s is also an inorganic fire-proof coating with silicate glass as the binder. In the early 1970s, some professional paint factories produced perchloroethylene and chlorinated rubber fire-proof paint. The above two kinds of fire-proof coatings have not formed a market in China because of their unsatisfactory fire-proof effect. It was not until the late 1970s that China began to study organic intumescent fire retardant coatings. The earliest intumescent fire retardant coatings are B60 - 1 acrylic intumescent fire retardant coatings and A60 - 1 modified amino intumescent fire retardant coatings developed by Sichuan Fire Science Research Institute of the Ministry of public security. Since then, China's organic intumescent fire retardant coatings have developed rapidly. So far, China's fire retardant coating production enterprises have grown to more than 200, with sales of__ With a capacity of tens of thousands of tons, a cross departmental research and production system has been formed

decorative intumescent fire-retardant coatings can be divided into solvent-based and water-based coatings. The fire-retardant components of the two types of coatings are basically the same, so it is difficult to say how much difference their fire-retardant properties are. The solvent selected depends on the film-forming material used. Generally, chlorinated rubber, perchloroethylene, amino resin, phenolic resin, etc. are used as film-forming substances of solvent based fire retardant coatings, and the solvents used are No. 200 solvent gasoline, paint thinner, butyl acetate, etc. Generally, the film-forming materials of waterborne fire-retardant coatings are vinyl chloride vinylidene chloride lotion, styrene acrylic lotion, pure acrylic lotion, polyvinyl acetate lotion, etc. these materials are water-soluble

Copyright © 2011 JIN SHI