Carbon Black Effect

[plastilina1979]

We are a company working in extrusion of PVC over a polyester yarn.All our colours work properly ,exceed the black because the adherence with the polyester is not very good. I would like to know if the carbon black this additive has any lubricant effect or any effect which could decrease teh adherence between PVC and PES.
Thanks,
Plastilina

[Len]

plastilina1979

This may be a little off base, but I wonder if your problem is not associated w/ the CB, type; particle size, structure, etc that you are currently using. I'd guess that the difficulty you are having w/ adhesion between the PVC and PES is related to viscosity.

Rheological differences between the two polymers is causing problems w/ extrusion. Find an alternate carbon black w/ easeir dispersion and lower viscosity build up, lower the CB concentration, or use an alternative black pigment in the PVC.

Len

[DwightDixon]

Since you are getting acceptable adhesion when you use other colorants, I wonder if you are using concentrates added to pelletized PVC when you are extruding or are you using particulate color pigments added to the dry blend during mixing? If you are using color concentrates, maybe your concentrate supplier has made a mistake in their black formulation and added something that is getting in the way of the adhesion. If you are using powdered carbon black their ability to be wet out during extrusion and their ability to signifigantly effect the viscosity of the polymer in the liquid state could signifigantly effect how the dry blend should be processed. You may need to reoptimize the process.