The New EU Directive.
In the coming 6th amendment to EU Directive 90/128EEC there will for the first time be limits for primary aromatic amines in laminates. The limit is expected to be 20 ppb/100 ml test liquid for aromatic isocyanate-based adhesives.
This has confused many converters to believe that the new regulation will replace the limit of 1 mg Free NCO/1 kg laminate (qm(t) = 1 mg mg/kg). This is not correct and the previous regulation for 1 mg Free NCO will still be valid.
It has now been confirmed by Government authorities that in the future laminates has to meet both regulated limits.
This is perhaps logic because the aromatic amines limits regulate aromatic isocyanate adhesives, while the limits for 1 mg Free NCO regulate some isocyanates in plastic - both aromatic and aliphatic.
Some aliphatic laminating adhesives may need months to meet the limit of 1 mg Free NCO unless various cure-accelerating measures are taken.
The standard EU-test for establishing compliance with 1 mg Free NCO/1 kg laminate (qm(t) = 1 mg mg/kg) is slow and costly while the BgVV test for aromatic amines is much faster and less costly.
There are perhaps a theoretical way to establish compliance with the EU Limits for Free NCO by measuring the levels of aromatic amines, provided that an aromatic isocyanate-based laminating adhesive is used.
As the regulation for aromatic amines is related to the surface, and the regulation for Free NCO is related to the thickness of a laminate (1 mg Free NCO/1 kg laminate), it is theoretically possible, by the BgVV test to ensure compliance also with the EU regulation for Free NCO level.
The first condition is that a fully aromatic isocyanate adhesive is used as the BgVV test only measures aromatic amines. The second condition is that the limit for Free NCO is calculated based on the thickness of a laminate as suggested by CSL Food Science Laboratory, UK. (See below.)
The theoretical safety limits for aromatic amines are:
25 gr/m2 Laminate 0,195 mg/100 ml test-liquid.
50 gr/m2 Laminate 0,388 mg/100 ml test-liquid.
75 gr/m2 Laminate 0,583 mg/100 ml test-liquid.
100 gr/m2 Laminate 0,775 mg/100 ml test-liquid.
By meeting the limits on the above-mentioned conditions, a converter will be able to ensure that his laminates comply with valid EU regulation for 1 mg Free NCO/1 kg laminate.
CSL Food Science Laboratory at the Ministry of Agriculture, Fisheries and Food, Norwich, UK has issued a discussion document on this issue. To open the document from Dr. Laurence Castle, CSL, MAFF, UK
COMPLICATED LAMINATE COMBINATIONS.
Some film-combinations are more difficult than others. Usually, Nylon/polyethethylene combinations give the highest aromatic amine values. Particularly CPA or OPA laminated to WHITE Polyethylene, as well as CPA , or OPA laminated to LDPE with 2-4% EVA, are likely to have very high aromatic amine values. Also Alufoil/LDPE, and Alufoil/Metalocene based PE may give too high aromatic amine values. For example CPA laminated to WHITE LDPE with some adhesives may never attain a result below 4-5 mygr/100 ml unless special cure-accelerating measures are taken.