In short: An antiblock benchmark is decided by the trade-off, not by one property: how much the block force drops against how much haze the film gains. Run both additives at the same loading on the same line, and measure block force, haze and clarity, coefficient of friction, and screen pack pressure over a full run. A film that unwinds beautifully and looks cloudy has failed.
Antiblock works by putting particles at the film surface so that two layers cannot make intimate contact when they are wound together. The same particles that stop the layers sticking also scatter light. Push the loading up and the film separates beautifully and looks cloudy; pull it down and the film is clear and blocks on the reel.
So the question is never "which antiblock gives the lowest block force". It is "which antiblock gives me the block force I need at the least cost in haze", on my resin, at my film thickness, on my line. That ratio is the whole benchmark.
Everything else — feeding behaviour, screen pack life, coefficient of friction on the converting equipment — sits underneath that trade-off and decides whether the winner on the bench is still the winner after a full production run.
Same resin, same masterbatch let-down ratio, same die, same blow-up ratio, same line speed, same winding tension, same day. Antiblock performance is extremely sensitive to line conditions, and a comparison run a week apart on a differently-set line tells you nothing.
Run at two loadings. The trade-off curve is what you are trying to find, and you cannot see a curve from one point. If the candidate gives the same block force at a lower loading, that is the result — lower loading means less haze and less cost.
Let the reel sit before you test it. Block force develops over time and under the pressure of the reel's own weight. Testing straight off the winder flatters every additive equally and tells you nothing about what the converter will find next week.
Block force after conditioning. Use your own method and stick to it, but condition the samples under load and at a defined temperature before testing. Consistency of method matters more than which method, because you are comparing two films, not certifying one.
Haze and clarity. Measure both — they are not the same thing. Haze is wide-angle scatter and reads as cloudiness; clarity is narrow-angle and reads as how sharply you see print or product through the film. Packaging customers reject on clarity more often than the haze number predicts.
Coefficient of friction. Film that will not block but will not slide through the converter's equipment has traded one problem for another. Measure film-to-film and film-to-metal, and involve whoever runs the bag machine before you sign the change off.
Screen pack pressure over a run. This is the property that only shows up at production scale. Log the pressure rise across a full run, not a short trial. A candidate that lifts pressure faster shortens screen life and eventually costs you the line, whatever the film looks like.
Our starting point for clear-film antiblock is CENSIL 773, with CENSIL 779 alongside it, and CENSIL 165GR or CENSIL 185GR where the question is feeding and dust control on the masterbatch line rather than optics in the film. Sending the powder and the granular form together answers two questions in one trial.
Customers commonly benchmark clear-film antiblock against products such as W. R. Grace SYLOBLOC® 250 and Evonik ACEMATT® and SIPERNAT® antiblock grades. Naming them locates a grade; it is not a claim of equivalence, and the decision is made on your line.
If your problem is feeding stability, screen pressure or dust in the compounding area rather than block force, say so at the enquiry stage — the grade we would send is different, and so is the test plan.
No, and matching it exactly is the wrong target anyway. What matters is hitting your block-force requirement at an acceptable haze on your resin and line. We send the candidates and the test plan; your line decides.
It reflects how the additive disperses and what survives into the melt. It is a property of the combination — additive, carrier resin, let-down, screw and screen — which is why it has to be logged over a full run rather than inferred.
Sometimes, by moving along the trade-off curve rather than off it: a different particle population can reach the same block force at a lower loading, which buys back haze. Whether that works on your film is what the two-loading trial establishes.
Both, if the masterbatch line is part of the question. The granular forms exist for feeding stability and dust control; the powder forms for optics. One trial can cover both.
Third-party product and brand names are the trademarks of their respective owners and are used here only to identify the reference points customers benchmark against. No equivalence, affiliation or endorsement is claimed or implied.
The material you use now, the formulation or resin, the equipment and the target you need to hit. That is enough for us to say whether we have something worth testing.
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