Lubricants

[jmteixeira]

Hi! A small question about lubricants:

Is there any incompatibility between metalic stearates (zing e.g.) and PC/ABS? If so, which would be the correct lubricant?

 

[Pud]

I guess you will find there are already metallic stearates in ABS - used as release agents.

Compatibility with some colour pigments may be an issue but I suspect very remote.

Rgds

Harry

 

[jmteixeira]

The problem, I suspect, shouldn't be with the ABS component, as we have processed ABS with no problem in the past, only a decrease in the lubricant perfomance.

But now, the end product shows some strech marks that dissapeared with the substitution of the stearate (metallic for an amide). I see several references for "ester-vulnerable polymers such as PA, PC and ABS" but I'm still looking for the reason.

 

[patprimmer]

Stearates have been used for years as a lubricant , mould release or nylons.

I am about 90% sure it has been used with PC.

Regards

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[Demon3]

Pat is right, there is tons of metallic stearate in ABS from the production process. There is no real incompatibility.

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[jmteixeira]

As I said, I do not believe the problem to be with the ABS component. In our experience with this resin, we never had this kind of problems. We only had this problem when processing PC/ABS, which is why I think the problem is in the conjugation of polycarbonate with metallic stearate.

The fact is that the substitution of zinc stearate for an amide stearate solved completely the problem. The reason behind is still to be found.

 

[Demon3]

Polycarbonate is the most sensitive of all polymers to additives (environmental stress cracking). Having said that, PC/ABS is an extremely common blend so it can work well. I would expect metallic stearates to attack polycarbonate in wet / warm conditions by hydrolysing the polycarbonate. If you are worried then try ABS/polyamide, it has similar properties to PC/ABS.

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell