Moisture Scavenging Packaging For Diagnostic Test Strips, Pharmaceuticals, And Other Moisture Sensitive Products

Moisture barrier packaging is used to protect a wide range of products from damaging levels of humidity. Desiccant sachets are often used to enhance the moisture protection by absorbing any initial moisture in the package headspace and any moisture that permeates through the barrier packaging. An alternative to the use of desiccant sachets is to make the desiccant material an integral part of the packaging, preferably blended with the sealant or product contact material. This prevents contamination of the package contents in the event of desiccant leakage from a sachet and eliminates the risk of accidental ingestion of the sachet when used with food products. Any conventional desiccant including silica gel, molecular sieves, magnesium sulfate or calcium sulfate can be used. However, calcium oxide is preferred because it reacts with moisture to form calcium hydroxide. This produces very low moisture levels and is not reversible at temperatures normally encountered by packaging. Magnesium sulfate can be used when it is desired to control humidity above about 32% RH.

Background
It is widely known that atmospheric moisture and oxygen may cause food to become spoiled and inedible or otherwise undesirable. In addition, many medical products such as pharmaceutical and test strip products may be damaged by atmospheric moisture. Typically, moisture-sensitive products are placed in barrier packaging containing polymeric materials such as High Density Polyethylene (HDPE), Saran® (PVdC-MA copolymer), oriented polypropylene (OPP), metallized OPP, or metallized polyester (met-PET). In addition, aluminum foil will prevent the transmission of moisture through packaging.

Although these moisture barrier polymers restrict the transmission of moisture into a package, some moisture will slowly permeate into the package to; eventually, adversely affect the product. Even when aluminum foil blocks the transmission of water through package structure, the sealed edges of the package will provide a transmission path for moisture into the package interior.