Adipic migration

Raw Materials. PVC is inherently a hard and brittle material and very sensitive to heat it thus must be modified with a variety of plasticizers, stabilizers, and other processing aids to form heat-stable flexible or semiflexible products or with lesser amounts of these processing aids for the manufacture of rigid products (see Vinyl polymers, vinyl chloride polymers). Plasticizer levels used to produce the desired softness and flexibihty in a finished product vary between 25 parts per hundred (pph) parts of PVC for flooring products to about 80—100 pph for apparel products (245). Numerous plasticizers (qv) are commercially available for PVC, although dioctyl phthalate (DOP) is by far the most widely used in industrial appHcations due to its excellent properties and low cost. For example, phosphates provide improved flame resistance, adipate esters enhance low temperature flexibihty, polymeric plasticizers such as glycol adipates and azelates improve the migration resistance, and phthalate esters provide compatibiUty and flexibihty (245). 

Plasticizers soften the film and increase the adhesion and the setting speed. The most common are phthalates, adipates and benzoates. The amount added can be in a broad range of 10-50%. They affect the swelling and softening of the PVAc emulsion particles, ensure film formation at room temperature, and the tack of the still wet adhesive. They also provide improved moisture resistance of the bond. Disadvantages are the lower resistance of the bond line against heat, possible migration of the plasticizers and enhanced cold flow. 

Polymeric plasticisers have been used as partial or total replacements for di(2-ethylhexyl)adipate (DEHA) in PVC cling film to reduce levels of plasticiser migration when used for food contact. Castle et al. [792] used SEC in combination with H 1-NMR and MS for the isolation and identification of seven individual oligomers in the most commonly employed polymeric plasticiser, poly(butylene adipate) (Reoplex R346). Both mass (RI) and specific ester moiety (UV) were being monitored (Figure 4.21). The oligomers were identified... 

The enforcement in Denmark of EU Directives on food packaging materials is discussed. Enforcement activities considered include studies of total migration from food contact materials, migration from kitchen-and tableware made of melamine plastics and migration of di(2-ethylhexyl)adipate from plasticised PVC films. Activities which need to be undertaken to increase the effectiveness of enforcement activities in the field of migration are described, including development of selfinspection programmes in industry, European network of enforcement, more rapid analysis and provision of information to the consumer. 2 refs. 

Castle, L., Mercer, A.J., Startin, J.R. and Gilbert, J. (1987). Migration from plasticized films into foods. 2. Migration of di(2-etylhexyl) adipate from PVC films used for retail food packaging, Food Addit. Contain., 4, 4, 399 06. 

Food is the major source of exposure of the general population to di(2-ethylhexyl) adipate because of its migration, particularly to fatty foods such as cheese and meat, from PVC films used for packaging that have been plasticized with di(2-ethylhexyl) adipate (lARC, 1982 Castle et al., 1987 Startin et al., 1987 Page Lacroix, 1995 WHO, 1996). 

Badeka and Kontominas (1996) reported the efifect of microwave heating on the migration of di(2-ethylhexyl) adipate from food-grade PVC into olive oil and water. Migration was dependent on heating time, microwave power setting, the nature of the food simulant and the initial concentration of the plasticizer in the film. 

Petersen et al. (1997) reported that, compared with a specific migration limit of 3 mg di(2-ethylhexyl) adipate/dm from PVC cling films used in Denmark, 77% of the films used for fatty foodstuffs sampled from importers, wholesalers and retail shops... 

Mercer, A., Castle, L., Comyn, J. Gilbert, J. (1990) Evaluation of a predictive mathematical model of di-(2-ethylhexyl) adipate plasticizer migration from PVC film into foods. Food Add. Contam., 7, 497-507... 

Petersen, J.H., Lillemark, L. Lund, L. (1997) Migration from PVC cling films compared with their field of application. Food Add. Contam., 14, 345-353 Reddy, J.K., Reddy, M.K., Usman, M.L, Lalwani, N.D. Rao, M.S. (1986) Comparison of hepatic peroxisome proliferative effect and its implication for hepatocarcinogenicity of phthalate esters, di(2-ethylhexyl) phthalate, and di(2-ethylhexyl) adipate with a hypolipidemic drag. Environ. Health Perspect., 65, 317-327 Reisenbichler, H. Eckl, P.M. (1993) Genotoxic effects of selected peroxisome proliferators. Mutat. Res., 286, 135-144... 

Primary exposure to dibutyl adipate is from skin contact with cosmetics and sunscreens containing this compound. It can also migrate from resins using this material as a plasticizer during the life cycle of the product and after disposal. 

Complex esters like glycerol adipate stearate or pentaerythritol adipate oleate (Loxiol G 70 series) have been fully assessed by EFSA for the use in food-contact materials. These esters still function as lubricants but due to higher molecular weight migration from food-contact material to food is crmsiderably reduced. 

Migration from PVC/Poly(butylene Adipate) Blends. 175... 

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