Safe ceiling on blow molded HDPE filled with Calcium Carbonate......

[sunewu]

All,

What the Calcium Carbonate safe content ceiling (%) blow molded HM HDPE can be filled with? The application is seating, furniture, that required to pass BIFMA tests.

What's the guide line of measurement: volume or weight?
How many re-grind cycles can we go?
How about the colorant?
Is it a good practice to use on living hinged HDPE?

ew

 

[patprimmer]

"What's the guide line of measurement: volume or weight?"

This depends to much on design to possibly answer

"How many re-grind cycles can we go?"

This depends on safety margin in design and processing conditions and %age regrind used, but HDPE is fairly stable and can be reused more than many other materials.

"How about the colorant?"

Some colourants will have a pronounced effect on properties. You need to investigate each colour you will use and test the design in the worst case. The colour that gives the highest mould shrinkage will be more rigid but more brittle with lower elongation.


Regards
Pat
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[patprimmer]

HDPE is not the best for living hinge. fillers have a further bad effect on that performance.

Regards
Pat
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[sunewu]

Pat,

Thanks!

"What's the guide line of measurement: volume or weight?"

>>weight

"How many re-grind cycles can we go?"

>>puzzle is the ash result never stays stable.

"How about the colorant?"

Some colourants will have a pronounced effect on properties. You need to investigate each colour you will use and test the design in the worst case. The colour that gives the highest mould shrinkage will be more rigid but more brittle with lower elongation.

>>there are variuos of 'hot colors' demanded by the marketing

 

[sunewu]

Pet,

The living hinge is 'one-time-deal' to save shipping costs and yet the folded product needs to withstnd human body weight. My concern is if CC degrades the integrity of the livig hinge during its life span even the product may pass the lab test.

ew

 

[patprimmer]

Once only if designed right should be OK.

Regards
Pat
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[patprimmer]

If your ash result never stays stable, either your lab technique is poor or your compounder is doing a poor job.

From my memory, the BIFMA test is quite severe. You will have problems if your methods and material are not consistent.

Regards
Pat
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[Demon3]

I would stick to 40 weight % calcium carbonate. This is standard. You can go higher but sacrifice properties (impact and elongation) quickly above that level.

Calcium carbonate does not degrade polyolefins. The only issue could be some small adsorption of antioxidant and that is overcome by adding more antioxidant or by using surface treated calcium carbonate.

You can reprocess the material many times without loss of properties assuming you add more antioixidant.

Chris DeArmitt - PhD FRSC CChem
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[sunewu]

Is your rule of 40% on single wall applications (bottles)? Can it apply to double walls with tackoff structure?
We tried from 5 to 50% and some projects stay around 20-30%. They range from 5 to 30 lbs parts. The issues in these (10+) years are:
1, tail not consistent
2, tackoff not consistent
3, wall distribution hard to control
4, parts don’t shrink the same way resin and mold vendors provide
5, colors hoard to control.