In unsaturated polyester resins, different ways to participate in different flame retardants, made of flame-retardant unsaturated polyester resin, you can reach the suppression of fire spread, to prevent extinguishing, the purpose of self-extinguishing the fire. Flame retardant unsaturated polyester resin can be divided into two general categories: one is added flame retardant resin, that is, in the unsaturated resin to participate in the physical mixing of additive flame retardants, which is currently the most commonly used A class of flame-retardant resin; one is the reaction of flame-retardant resin, that is, with the reaction of flame retardant polycondensation polyester reaction process as a unit of reaction into the unsaturated polyester chain, such flame retardant resins are often used in On the functional requirements of the products. These are two rare types of flame retardant resins, the recent development of shrinkage fire retardant coatings with unsaturated resin, flame retardant unsaturated polyester resin should be a new type.

1. extinguished and flame retardant mechanism

1.1 extinguishing mechanism

Unsaturated polyester resins, like many polymers, are pyrolyzers that degrade when subjected to a certain amount of heat to form chains that degrade or chain-break, with the consequent occurrence of flammable hydrocarbon gases such as styrene, dimer Styrene, etc., in addition, there are non-volatile residue, with the flammable gas molecules escape, leaving a lot of holes in the resin body, oxygen in the air immediately added into the resin under the action of oxygen and then The onset of oxidative degradation and the release of heat energy, the temperature of the resin matrix increases, with the external radiation is absorbed and oxidative degradation enhanced, the reaction from time to time to carry out, when this effect reaches a certain level, that encounter outside fire , Or the basic temperature accumulation to the critical temperature, will certainly lead to the scene of extinction. Flammable substances, temperature, oxygen is extinguished three elements, one of the three missing, the flame will go out. The response process is as follows:

1.2 flame retardant actual

Unsaturated polyester resin flame retardant, secondary treatment The following results:

(1) make the resin difficult to extinguish, put out the effort to extend

(2) Once the resin is on fire, it can extinguish itself from the fire.

(3) does not occur or rarely occurs when the smoke and toxic gases.

Resin flame retardant is modified polyester composition and structure, or the introduction of non-flammable resin elements into the resin, the resin at low temperature decomposition of non-flammable elements containing volatile gases, high-boiling liquid, etc., cut off One or several baking conditions, changing the resin cracking process, destroy the resin decomposition morphology, to achieve the resin extinguishing difficulties, from the fire self-extinguishing, to prevent the purpose of extinguishing.

Flame retardants are usually compounds containing non-combustible elements, including compounds of halogen elements-iodine, bromine, fluorine, etc., phosphorus and phosphorus-containing compounds, oxides of antimony and boron and their salts, hydrated alumina, Magnesium oxide.

When the unsaturated resin contains halogen, the extinction temperature can be increased from about 375 ℃ to about 465 ℃, and the complete decomposition temperature is about 550 ℃. Obviously, the flame retardant can not be improved.