How to solve the problem of powdering when adding polypropylene flame retardant to hollow boards?
During the production process of PP hollow sheets, a problem that is often encountered is the precipitation issue of PP flame retardants. Specifically, it manifests as powdering on the surface of the sheets, which affects the adhesiveness and transparency of the sheet surface, among other aspects.
First of all, let's analyze the reasons for the precipitation.
On the one hand, PP is a non-polar material, while commonly used flame retardants are generally polar materials. This leads to compatibility problems at the contact surface between the two. The poorer the interfacial compatibility is, the more likely the precipitation problem will occur.
On the other hand, affected by the ambient temperature, substances inside PP will gradually move to the surface, especially small-molecule flame retardants. This is also the reason why phenomena such as mold sticking and mold fouling occur during the injection molding process. In addition, precipitation may sometimes appear on the surface of the molded parts after they have been stored for a period of time. The migration rate of flame retardants is positively correlated with temperature. Within the decomposition temperature range of flame retardants, their precipitation rate will significantly increase as the temperature rises. At a constant temperature, precipitation is also related to time to some extent.
It should be noted that non-precipitating flame-retardant PP does not mean there is no precipitation at all. It just reduces the migration of PP flame-retardant masterbatch to a great extent. Currently, non-precipitating flame-retardant PP is often based on overly high technological costs. Therefore, low-cost anti-precipitation remains a topic that needs to be improved for current flame-retardant PP materials. After understanding the causes of precipitation, Hangzhou HAFU will tell you how to prevent it:
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Use grafting auxiliaries to increase the compatibility between the flame retardant and PP;
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Increase the migration resistance between the flame retardant and the resin and reduce the migration rate of low-molecular-weight flame retardants. This can be achieved by adjusting the components inside the flame retardant.
