Melt Blown Polypropylene

I received a request for a polypropylene the other day. The customer was looking for a grade that could be used for making “melt blown” fabric. I was not familiar with this process. You can see it in action in the above video. The polypropylene grades that are used for this have melt flows in the 1200-1500 g/10 minutes range (yes, you read that right).

The process uses an ordinary extrusion line but a high pressure gas is injected into the die which aerosol-izes the melted material and sprays it onto a roller.

I have been in this business for a while but this process was new to me.

Condensation and Polypropylene

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A common and frustrating problem with polypropylene materials and especially filled polypropylene materials is surface moisture on the pellets. Polypropylene is not hygroscopic so it does not absorb moisture out of the atmosphere but if the pellets have moisture on the surface, it will cause the same problems as you would experience running wet hygroscopic material like nylon. You will experience splay and loss of physical properties.

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