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WeT STrengTh InnovaTIonS world pulppaper40 to minimise epi hydrolysis and to minimise chloride ion formation. After the initial alkylation step the reaction mixture is heated to 60-80oC . This step results in further conversion of ACH functionality to azetidinium AZE functionality Figure 2 and further crosslinking to build a PAE resin of the desired molecular weight. The reaction is quenched with acid typically sulfuric acid at the target viscosity and cooled to less than 25oC before pumping to storage. Initial concerns about epi by-products in Pae technology were related to the potential hazard to human health when handling the product and the impact they had on the environment Pae reSInS ePI By-ProDuCTS In PaPer Initial concerns about epi by-products in PAE technology were related to the potential hazard to human health when handling the product and the impact they had on the environment. The focus in recent years has been the potential for these epi by-products to enter the food chain by migration from various food contact grades. After much review and assessment of such risks the German Federal Institute of Risk Assessment Bundesinstitut fr Risikobewertung BfR provides a series of recommendations XXXVI for the levels of 13-dichloro-2-propanol 13- DCP and 3-monochloro-12-propandiol 3-MCPD that may be extracted with water from a paper sample or product manufactured for different types of food contact grades of paper. For all food contact paper grades the recommendation states that the 13-dichloro-2-propanol must not be detectable in water extract of the finished product detection limit 2gl. The transfer of 3-monochloro-12- propanediol into the water extract of the finished product must be as low as technically achievable a limit of 12gl must not be exceeded in any case. While the BfR recommendation for the water extract is the same for all the different types of paper grades the sample size and the method of aqueous extraction must be considered to appreciate what this means in terms of levels of the allowable 13-DCP and 3-MCPD in paper. Figure 1. Polycondensation of adipic acid and diethylenetriamine DETA Figure 2. Typical PAE Resin Manufacture and Formation of Epi By-products.