Nowadays, it has gradually become a habit to use flame retardants to reduce the incidence of fire. However, there are many problems in the use of flame retardants. Let me share with you the problems with flame retardants and the specific solutions to each problem.

The precipitation of flame retardants not only often produces mold scale, powder caking and sticky mold in the process of injection molding, but also often occurs in the finished products, resulting in white fog-like substances affecting the appearance of products and resulting in decreased flame retardancy.

A: precipitation causes

1. Compatibility between flame retardant and PP substrate resin

Flame retardants in PP resins are generally in two states: filling the resin in a similar packing form, and the other type is evenly dispersed in the resin in a melting state. Because PP is a non-polar material, the interface compatibility between polar flame retardants and PP will be a problem. The worse the interfacial compatibility is, the easier it is to produce 2

PP is a semi-crystalline substance with a low glass transition temperature. When the ambient temperature is higher than its glass transition temperature, the thermal movement of amorphous chain segment will be accelerated with the increase of temperature, making it easier for small molecule flame retardants with poor compatibility with PP resin to overcome the resistance and migrate to the surface. This is also the reason why the surface of the product will sometimes precipitate after a period of time.

Two: the solution

1. The introduction of strong polar groups (such as amine group, carboxyl group, epoxy group, etc.) to enhance the interface between the flame retardant and PP can effectively reduce the problem of flame retardant precipitation.

2. To improve the migration resistance between flame retardants and resins, and reduce the migration rate of low-molecular weight flame retardants: reducing the temperature to weaken the movement between the chain segments or to improve the polymerization degree of flame retardants and reduce the molecular weight distribution width becomes an effective measure to reduce the precipitation of flame retardants.

Precipitation-free flame retardant PP is not completely free of precipitation, it only greatly reduces the mobility of the flame retardant. The current precipitation-free flame retardant PP is usually built on the high technical cost, so the low cost of anti-precipitation is still a topic that needs to be improved.