Application and development of phenolic foam

Phenolic foam is known as the "king of heat preservation", which was used in the heat preservation of missiles and rocket heads in the early days. In recent years, due to the high-rise buildings, transportation, ships, aviation, space technology and other aspects of synthetic foam; The thermal stability and flame resistance of phenolic foam are strictly required, which makes it develop more rapidly. As a new type of multi-purpose foam material, phenolic resin foam is widely valued for its heat resistance, flame resistance, self extinguishing, flame penetration resistance, and no dripping in case of fire.   

Phenolic foam is a foam formed by taking phenolic resin as the main raw material, adding curing agent, foaming agent and other auxiliary components, and dispersing the gas generated by foaming agent into the resin while crosslinking and curing the resin. It has many excellent properties. 1 first, heat-resistant cured phenolic foam has a structure including several phenol rings and connected by methylene bridges. It can be seen from thermodynamics that methylene bridges are one of the stable connections with little temperature influence in organic connection, which makes phenolic foam have excellent thermal stability. It can be used for a long time at 150 ℃, and the instantaneous working temperature can reach more than 200 ~ 300. Its high temperature resistance is obviously superior to other foam plastics. 2 "Flame retardant" is also prominent. Phenol molecule is a good free radical absorber. During the high-temperature decomposition process, the free radicals produced by the broken methylene bridge are quickly absorbed by the phenol molecule, preventing the reaction from continuing. This phenomenon makes it extremely difficult for the phenolic foam to burn. The oxygen index of the phenolic foam is 50, without adding any flame retardant additives, and the flame retardant grade is incombustible grade B1. The oxygen index of the high-density phenolic foam added with inorganic filler can reach 70, and its combustion performance can meet the requirements of incombustible grade A2 of German din4102 building materials. Resistance to flame penetration.

According to experts, under the direct action of flame, phenolic foam has no carbon deposition, no dripping, no curling and no melting. After flame combustion, the foam remains basically, but a layer of "graphite foam" is formed on the surface, effectively protecting the foam structure in the layer. It is also "low toxic and low smoke" - there are only carbon, hydrogen and oxygen atoms in the phenolic molecule, which can only produce these three products during high-temperature decomposition, and there is no other toxic gas except a small amount of CO; The smoke density of phenolic foam is 5.0%, while that of high-density phenolic foam is only 2.3%, which is quite low compared with 74% of flame-retardant PU foam. 3 thermal insulation: phenolic foam has uniform and fine closed cell structure and low thermal conductivity. Its thermal insulation performance is equivalent to that of PU foam and better than that of PS foam. Its thermal insulation performance is about twice that of mineral wool, light cork, perlite, glass wool and other traditional thermal insulation materials. Wide temperature range. The strength of phenolic foam is not significantly affected by temperature. It does not shrink or brittle at low temperature (even - 196 ℃), and its mechanical strength is basically unchanged. Under continuous stress at 130 ℃, it can maintain 90% of the strength at room temperature. The operating temperature range is generally - 150~150 ℃. Corrosion resistance and aging resistance: in addition to being eroded by strong alkali, phenolic foam can resist almost all the corrosion of inorganic acids, organic acids and salts.  

Phenolic foam is also recognized internationally as a new type of thermal insulation material with great development prospects. Because, this new material is essentially different from the material obtained by adding flame retardant to common polymer resin; It does not burn, melt or emit toxic smoke in fire, and has the advantages of light weight, non-toxic, non corrosive, heat preservation, energy conservation, sound insulation, low price, etc. It does not need Freon foam, has no environmental pollution, good processability, and is convenient for construction. Its comprehensive performance is unmatched by various temperature preservation materials at present. It is generally used for thermal insulation of central air-conditioning systems in hotels, apartments, hospitals and other high-grade and high-rise buildings (in recent years, most of the central air-conditioning systems in high-grade buildings in Hong Kong have changed to phenolic foam materials). It has indisputable comprehensive advantages in cold storage and cold storage, as well as thermal insulation of industrial pipelines and equipment used in petrochemical industry, building partitions, external wall composite panels, suspended ceilings, acoustic panels, etc. It solves the problems of poor fire resistance of other organic materials, while inorganic materials have high water absorption, are easy to "dewing", skin itch during construction, etc. It is the third generation of thermal insulation materials for air conditioning systems and various electrical appliances.

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