Inks, additives residues

Lamination Inks. This class of ink is a specialized group. In addition to conforming to the constraints described for flexo and gravure inks, these inks must not interfere with the bond formed when two or more films, eg, polypropylene and polyethylene, are joined with the use of an adhesive in order to obtain a stmcture that provides resistance properties not found in a single film. Laminations are commonly used for food applications such as candy and food wrappers. Resins used to make this type of ink caimot, therefore, exhibit any tendency to retain solvent vapor after the print has dried. Residual solvent would contaminate the packaged product making the product unsalable. 

Arsenical or mercury compounds are detected by evaporating a quarter of a litre of the ink and heating the extract with 1-2 c.c. of concentrated sulphuric acid and 5-10 c.c. of fuming nitric acid until nitrous vapours are eliminated, the addition of nitric acid and the heating being repeated until a perfectly colourless liquid is obtained (Rothe). The sulphuric add is then expelled and the residue tested for arsenic and mercury by the ordinary analytical methods. 

Three case studies have been selected in order to draw out some of the principles and considerations described above. They are (i) the migration of a residual monomer from a can coating (ii) the migration of an additive from a plasticised plastic film (iii) the migration of a photoinitiator used in a printing ink. 

Compound 14 may be isolated from the urine of patients with Sand-hoff s disease (GM2-gangliosidosis variant O).62 Fundamentally, it is a diantennary oligosaccharide bearing an additional, so-called intersecting GlcNAc residue (9), /3-(l—>4)-l inked to Man-3. The 500-MHz, H-n.m.r. spectrum of 14 is given in Fig. 15, and the n.m.r. data are presented in Table VII. 

Reported volume resistivities for printed patterns formed from commercial silver-based inks are higher than that of bulk silver. This occurrence reflects the fact that sintered ink patterns contain non-ideal defects such as incomplete particle-to-particle contact, incomplete sintering between contacting particles, residual porosity, and the presence of non-conductive additives. The morphology and extent of void formation in two representative sintered silver nanoparticle inkjet inks are illustrated in Fig. 1. 

After curing, the fully reacted polyurethane resin formed is no longer chemically active and is not a hazard to health unless heated to the point of decomposition. Handling materials containing prepolymers is not likely to give rise to an inhalation hazard from the isocyanate unless they are heated, sprayed or distributed into the air as dust before the curing process has had time to go to completion. This could happen in some printing processes where the characteristics of the ink and the process can lead to the production of spray. In addition, solvents are used in some ink formulations and these are dried by the application of heat, which would drive off any residual isocyanate as vapour. 

Castle L, Damant AP, Honeybone CA et al (1997) Migration studies from paper and board food packaging materials. Part 2 survey for residues of dialkylamino benzophenone UV-cure ink photoinitiators. Food Addit Contam 14(l) 45-52 Centers for Disease Control (CDC) (2013) Fourth national report on human exposure to environmental chemicals, updated tables. Sept 2013, urinary benzophenone-3, downloadable as PDF at http //www.cdc.gov/exposurereport/pdf/FourthReport UpdatedTables Sep2013. pdf. (Centers for Disease Control and Prevention, http //www.cdc.gov/exposureteport/. Accessed 18 Feb 2014... 

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