The Effect of Coating Process and Additives on EVA Coated Tyvek® for Gas Sterilizable Medical Packaging Applications

Tyvek (R), as an ethylene oxide (EtO) gas sterile medical packaging material with a high-gas permeation and serving as an excellent microbial barrier, must be coated with heat-sealable adhesives to thermally seal various plastic packaging trays or films. Tyvek (R) sheet coated with heat-sealable adhesives must have both porous structure and good sealing strength to various substrates. In this study, an acid pre-coating method was distinctively introduced to minimize reactions between the blowing agent and acid during mixing, to resultantly generate ethyl vinyl acetate (EVA) layers with porous structure on Tyvek (R) sheets. To determine the feasibility of applying the as-prepared coated Tyvek (R) as a sterile medical packaging material, we investigated the properties of the coating solution and coated Tyvek (R) as a function of process and additive composition. Finally, EtO gas sterilization tests were performed, and property changes in the coated Tyvek (R) were investigated. Properties of the coated Tyvek (R) were strongly dependent on the pre-coating process and the composition of various additives. Pre-coating with citric acid led to less of a reaction between citric acid and ammonium carbonate as a blowing agent during mixing and resulted in both good seal strength and air permeation for the coated Tyvek (R) sheets. The coated Tyvek (R) sheets, composed of a water-based EVA emulsion solution with various additives, were not affected by the EtO sterilization process and yielded good resistance to humidity, EtO gas and vacuum cycles. The coated Tyvek (R) sheets prepared by applying an acid pre-coating may be a promising candidate for gas sterilizable medical device packaging materials. Copyright (C) 2017 John Wiley & Sons, Ltd.