PVC and its MONOMERS

Hi,
Please help me with the following problem as I am not chemically wise :-( A spec of aluminium foil used for packaging of food stuff indicates
that there is 2 g of PVC per 1 sq m. The EU directive puts a limit of 1 milligram of PVC MONOMER per 1 kg of foil. So, is that foil OK or it exceeds the allowable limit of PVC monomer ?
I know that even up to 80% of PVC can be in form of additives and only 20% could be actual monomers. So, even if it is assumed that there is 20% of monomers in the 2g of PVC does it mean that the foil does or does not exceed the EU requirement.
Many thanks in advance,
George
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
You need to be more clear and precise here. The EU directive most likely refers to the residual amount of vinyl chloride monomer on the coating not the amount of PVC polymer. PVC is poly(vinyl chloride) and is relatively inert as long as it is below 150 C. PVC is made by polymerizing vinyl chloride. Typically, the amount of residual vinyl chloride monomer is measured in the parts per million or even billion level. You'll need to ask your supplier for that information. Referencing the exact EU standard will aid them in helping you determine if you are in compliance.
Larry Effler

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Many thanks for your answer :-))))

It does not seem so...
http://europa.eu.int/comm/food/food/chemicalsafety/foodcontact/leg_files/78_142_en.pdf

The construction of the foil is as follows :
a. aluminum layer b. primer ( PVC) c. glue d. lacquer
When they make the foil it is heated to temperature over 150 C (curing the lacquer coat). In this temperature the layer PVC breaks down to some toxic compounds. In Germany they banned foils like that some 6 yeras ago.
Many thanks again,
George

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@interia.pl (Jerzy Zi?ba) wrote in message

http://europa.eu.int/comm/food/food/chemicalsafety/foodcontact/leg_files/78_142_en.pdf
Time is just as important as temperature. The lacquer most likely cures quickly at 150 C, so the exposure time is short and unlikely to cause the PVC to degrade. Even so, it is impossible to predict the amount of monomer in the foil so you will have to have a sample analyzed.
John
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The reg calls for maximum extractable vinyl cloride monomer. Don't confuse this with the amount of PVC polymer. You should get a compliance statement from the manufacturer. Frank
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Frank is right. The regulation states that the for food packaging, maximum amount of residual vinyl chloride monomer is 1 mg of monomer per kg of PVC polymer. In other words, 1 part per million of vinyl chloride monomer (1.0E-06 g of monomer for every 1 g of polymer).
You'll either need to get a compliance statement from your supplier or submit a sample of your adhesive to a certified outside laboratory for testing. I'm not familar with any of the compliance labs in Europe. Does anyone else know?
Larry Effler

confuse
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Who cares what a bunch of crybaby eurowhiners worry about anyway?-Jitney
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@yahoo.com (jitney) wrote in message

If your business (or your employer) is trying to sell products in Europe, they certainly care.
I've worked for 5 different companies in 7 different industries over my 14 year career. The companies have always sold products globally and have always had foreign competition. The days of the US not worrying about the what the rest of the world thinks are gone - with the notable exception of unilaterally enforced regime change.
John
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Heh.
The (other) funny part is, the US is actually ahead of Europe on this particular regulatory curve. Content limits in the US, while recognized, are not formally legislated as they are in the EU. Residual vinyl monomer content of items for direct food contact in the US is recognized as safe at levels <10 ppb (billion) for rigid packaging, <5 ppb for flexible packaging. (Source: http://www.packaginglaw.com/index_Ask_PastQuestions.cfm?id#7 )
The EU actually allows more vinyl monomer (up to 1 ppm), so long as the manufacturer shows that it is non-migratory (no more than 10 ppb migrating to the packaged food).
Vinyl for infant chew toys is another matter.
Regards, R. David Zopf
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hmm... Looking at the definitions at the beginning of this document I interpreted it as 1 mg of monomer per 1 kg of foil...

?? One g of one substance has a different number of molecules than one g of any other substance. Hence there is no relation between PPM and mg of monomer in kg of polymer. Another thing is : does it mean that in one kg of PVC is just one mg of its monomer ?? If yes, what is the rest of this stuff i.e. the remaining 999 g of polymer ?
I am getting lost here ...

I think it is in Germany... the name of the city sounds like : Neeren
George
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ok. let's see if I can clear this up for you. What the regulation is concerned about is how much unreacted monomer is left in the final polymer. The whole idea is to minimize the amount of highly reactive small molecules from the relatively inert large molecules.
The polymer poly(vinyl chloride) is made by polymerizing the monomer vinyl chloride. Just like bread is made from flour. The regulation you have cited requires that any unreacted vinyl chloride monomer left in the final polymerized PVC must be less than 1 ppm (1 mg of monomer per 1 kg of polymer). If this regulation applied to bread, this would mean that you could have 1 mg of unreacted flour per 1 kg of polymer. Don't confuse the monomer, vinyl chloride, with the polymer, PVC. That's like confusing flour with bread.
Is that clear?
Larry Effler

maximum
PVC
Does
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jerzy Zi?ba wrote:

In polymer analysis, parts per million is usually interpreted to mean mass per unit mass, not molecules per molecule. Molecules per molecule is a useful figure when comparing molecules of similar sizes, but not so useful when for comparing monomer (tiny molecule) vs. polymer (giant molecule).
The average length of the polymer chains (molecules) in two samples of a given polymer are not necessarily equal. Also, the distribution of chain lengths may not be equal, even when the average is the same, but in order to keep it simple, let's ignore that fact for now. We'll assume that a given polymer sample consists of a certain number of molecules of residual monomer, plus a certain number of polymer chains of length N.
Greater chain length implies greater molar mass, so greater N implies fewer polymer "molecules" (chains) per 1 kg.
Completely neglecting the residual monomer content and any additives which may be present, 1 kg of a given PVC may very well contain a different number of molecules than 1 kg of another PVC if the chain lengths are not the same.
Now, suppose we are comparing two PVC samples, which both contain the same number of residual vinyl chloride monomer molecules, but which contain polyvinyl chloride chains of different lengths. Let each sample have a total mass of 1 kg. Count the number of molecules of monomer and polymer in each sample.
If the average length of the polymer chains in sample A is greater than the average length of the polymer chains in sample B, then there will be "more" vinyl chloride monomer in sample A than in sample B -- on a molecule per molecule basis -- when in fact the total monomer content in each sample is equal!
Compare mass to mass, and this problem goes away.

Probably significantly less than 1 mg, assuming the polymerization was reasonably efficient. These days, the amount of free vinyl chloride monomer in PVC is extremely low indeed. 1 mg/kg is the maximum allowed in Europe, but I would be very suprised to come across any PVC which contained that much.
If you want to know for sure, a good test method is headspace gas chromatgraphy. If you are concerned about how much vinyl chloride monomer will present at elevated temperatures, simply perform the analysis at elevated temperatures.
Hope this is helpful.
Dave Palmer
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@midway.uchicago.edu (Dave Palmer) wrote in message

VERY !! :-))) many thanks to you and all other guys who were kind to answer.. :-)))
It is quite clear that unless it is thorughly tested it will be impossible to come to any definite conclsions.
Thank you again...
George
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

In fact, since that european legistlation came into play, it is nearly impossible (for the resin manufacturers) to sell PVC resin if VCM levels are not below that mentioned ppm level. Further more - consider two aspects of PVC article manufacture: 1) PVC is not used neat but compounded to enhance its processability (mostly with stabilizers and lubricants) and its properties or lower it's cost. Of that, plasticized PVC contain 15%-45 % plasticizer, reducing the resin presence in a compound significantly. Some formulations can contain large amounts of CaCO3 filler. VMC theoretical level would drop, as now it is diluted by all the additives. 2) Any article needs to be formed, which requires heating to soften or melt the compound - VCM is volatile, much of it (of the residual level in the resin) would escapeduring that phase. It is often drops below detection levels in the final article, though mass spectrometry is becoming ever more sensitive...

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.