Patent ID: 7337709

Claim:
A preservative gas generating device comprising: a carrier sheet; a layer of a matrix forming plastic polymer material having a preservative gas generating compound dispersed therein, the layer of matrix forming material being adapted to permit generation of a preservative gas under operative conditions when moisture is present by the preservative gas generating compound at a controlled rate and to permit the gas to permeate out of the matrix formed by the matrix forming material, the matrix forming material being adhered to the carrier sheet in the form of a layer covering an area of the carrier sheet so as to form at least one discrete zone with a peripheral area of the carrier sheet surrounding the discrete zone(s) being substantially free of the matrix forming material; and a cover sheet secured to said peripheral area to enclose the layer of matrix forming material between the carrier sheet and the cover sheet; wherein either one of the carrier sheet and the cover sheet is permeable to the said preservative gas and the other sheet is impermeable to the preservative gas.