askralph

Jeff asks,

I have a client who is asking for specific information about corrugated performance at low temperatures (-20 degrees Celsius) for extended periods of time (up to 6 months).  I have not been given specific information about the contents of the boxes, but I suspect it to be clinical trial materials or something similar.  I expect them to be looking for some sort of performance guarantee.  Current board grade is 32 ECT C Flute.  Outside liner would be virgin paper.  The remainder of the box (medium and inside liner) is recycled paper.

Anything you can provide to help me with this?  Or can you direct me to the right place?  Thanks in advance for any help you can offer.

There just is not much out there, but here are a few things that we do know. Cold temperatures can cause strength degradation in corrugated packaging and other corrugated paperboard products. Moisture introduced from the repeated opening and closing of refrigerated units can also affect the strength of the corrugated container. Aqueous and UV coatings will certainly provide extended resistance to moisture on the boxes’ surface. However, what generally happens is the glue line is attacked by changes in atmospheric conditions. This is where we often see failure to the board itself.

Manufacture’s joints and/or flaps that are glued can also be subject to strength degradation at low temperatures. The same problem may be seen in boxes sealed with tape as the adhesives can become less tacky. There are tapes and glues that are marketed to offer better performances in both extreme low and high temperatures. While they may not help with the overall strength of the box, they contribute to the overall survivability and protection of the enclosed content.

Here is a link to the last industry wide study on freezer storage that we are aware of. It’s a bit over 70 years old, but still relevant. Note the added box strengths in the chart.

I’ll also include this link to the most recent report from the PMMI on the storage of Corrugated Packaging.

Does any of our other followers have any knowledge they care to share on their experience with long term or short term low temperature storage of products protected by corrugated containers?

— Ralph

Bobs asks,

Is burst testing and puncture testing done on triple-wall boards? I’m having trouble interpreting the minimum fiberboard requirements issued by NMFC Item 22 and UFC Rule 41. Specifically 1100 triple-wall, does the 1100 represent minimum burst strength of 1100 lbs. per square inch? Or does 1100 represent a puncture test value?

That’s a really good question. It is Mullen burst and not a Beach puncture. It is really based on the additive Mullen values of the liners. So if you were experimenting with low Mullen yet high SCT liner and strong mediums, it would be better to go to an ECT standard.

— Ralph

UPDATE

Miranda comments,

TAPPI T810 Section 1.2 states mullen burst is not applicable to triplewall board. If the test is being performed on triplewall it would not be clear what the results would mean.