1.The flame retardant mechanism of PN-based intumescent flame retardants generally includes three parts, that is, a carbon source (often a polyhydroxy compound, such as pentaerythritol), an acid source (such as ammonium polyphosphate, or APP), and a foaming agent (such as melamine). ), They form a carbon layer through the following interactions: ① At a lower temperature (about 150 ° C, the specific temperature depends on the nature of the acid source and other components), an acid source produces an esterified polyol and a Acid as a dehydrating agent; ② at a temperature slightly higher than the acid released, the acid and the polyol (carbon source) undergo an esterification reaction, and the amine in the system serves as a catalyst for this esterification reaction to accelerate the reaction; ③ The system melts before or during the esterification reaction; ④ The water vapor generated during the reaction and the non-combustible gas generated by the gas source expand and foam the system already in the molten state. At the same time, the polyol and ester are dehydrated and carbonized to form inorganic and carbon residues, and the system further expands and foams; ⑤ When the reaction is nearly complete, the system gels and solidifies, and finally forms a porous foamed carbon layer.

2. PN series intumescent flame retardant is composed of three parts: (1) acid source: providing acid required for esterification reaction; (2) carbon source: substance providing hydroxyl group or other groups required for esterification reaction; (3) Gas source: Provide the gas needed for system expansion and foaming.

3. Why do some P-N flame retardants stick to the water when extruding through the water tank?

The sliver sticks easily to water because some components of the flame retardant are more water soluble. When passing through the screw machine outlet, the sliver with a higher temperature contacts the cold water tank, and the powder is easy to precipitate. Therefore, the components in the flame retardant must be insoluble. water. The EPFR-100A and EPFR-100C flame retardants of our company are used in PP, and the above-mentioned sliver sticking phenomenon will not occur.

4. Why do different PPs add the same parts of flame retardants to different flame retardant efficiency?

Due to the difference in PP matrix, such as homo-PP and copolymerized PP, due to the difference in the internal olefin content, this is because the copolymerized PP has a PE side chain, and the H atom in PP is more active than PE; PP has less combustion heat than PE. It works together with the flame retardant at the beginning, and the PE decomposition temperature is high before it will work later; the PP substrate decomposition temperature is between 227-247 degrees, and PE is between 335-450 degrees, and the flame retardant decomposition temperature is between 260 degrees, PP and flame retardant match better.

5. Why is the effect of P-N series intumescent halogen-free flame retardants worse for glass fiber PP?

Generally speaking, as the amount of PP decreases and the amount of flame retardant increases, the flame retardant effect of the material will become better and better. Why is the relative reduction of PP in glass fiber (glass fiber is added), and the number of flame retardants remains the same, but The flame retardancy will be worse or even not flame retardant. This is mainly because the addition of glass fiber destroys the flame retardant mechanism of the PN expansion system. The glass fiber is distributed in various places in the plastic and has a great destructive effect on the closure of the carbon layer. As for not being able to isolate oxygen and achieve the effect of group combustion.

6. Why does P-N series intumescent halogen-free flame retardant lose the flame retardant effect after adding filler or other substances?

In order to reduce costs, many people have added fillers, such as calcium carbonate, barium sulfate, talc, and magnesium hydroxide, to P-N series intumescent halogen-free flame retardants, and found that the flame retardant effect will be lost. It is because the addition of the above filler changes the esterification reaction process, the acid source will partially react with the above filler, and the above filler destroys the formation of a carbon layer on the surface of the material, resulting in the failure of the mechanism.

For the same reason, the addition of certain carbon blacks and toners will also lead to loss of flame retardant effect. Therefore, some recycled PP materials may be partially filled with PP recycled and added to the new material, causing the system to add the aforementioned filling in disguise, making this system lose the flame retardant effect.

  7. Why does some PP produced with P-N flame retardants leave oil or powder on the surface after being left for a period of time (tens of days)?

As we mentioned, the composition of the flame retardant is composed of a carbon source, an acid source, and a gas source. If there is a substance to be precipitated, it must be one or more of the above substances. The water solubility is better. During processing, the material and the powder are dispersed by the strong mechanical force of the screw machine. After being left for a period of time, due to the continuous movement between molecules, substances of different polarities will slowly separate, and the powder will slowly Precipitation from the inside of the material to the surface. But our company EPFR-100A and EPFR-100C will not produce the above situation.