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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. |