Adsorptive composite barriers for packaging applications

#The invention broadly relates to packaging materials, more specifically to adsorptive composite barriers for packaging applications, and even more particularly to a method for selecting the materials and composition thereof for adsorptive composite barriers for packaging applications.

#Polymer-based composites filled with inorganic particulates have long been used for improving mechanical properties of thermoplastic and thermoset polymers. Composites loaded with moisture absorbers have been also proposed for the purpose of making desiccating liners and other internal parts of thermoplastic containers and controlling humidity in such containers, e.g., U.S. Pat. No. 6,130,263. Multiple electronic, automotive, pharmaceutical, diagnostic, and food packaging applications require very low humidity levels inside the package or encapsulated enclosure to protect moisture-sensitive products or components from exposure to environmental humidity. Increasingly, electronics and automotive electronics are shifting from the use of metal die castings for housings and components to the use of thermoplastics. This transition is fueled by the need to reduce weight and cost in an ever increasing competitive environment. Resulting from the rapid development pace of these applications, the selection process of thermoplastic resins often does not give consideration to the water vapor transport properties of such resins which directly impact the service life of the components or device. In conjunction with this trend is the miniaturization of components or devices which leaves little or no space for enclosed sorbents which results in inadequate or no moisture protection whatsoever. Currently, the selection and use of thermoplastics exhibiting the best passive moisture barrier characteristics often falls short of providing protection from moisture ingress over the desired service life of the component or device. Heretofore, enclosures of this type have essentially failed to provide a sufficient performance regarding prevention of moisture ingress.

#Several U.S. Patents focus on improving moisture transport into the desiccant-loaded composite in order to accelerate the desiccating effect of such composites by rapidly removing moisture from inside the package, especially when used as an interior part of the container. See, for example, U.S. Pat. Nos. 5,911,937; 6,130,263; 6,194,079; and, 6,214,255. The devices are inadequate for many described needs as they fail to prevent moisture ingress, but merely absorb moisture after it has entered an enclosure during packaging operations, during service time of a device or after opening of resealable containers.

#The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which:

#FIG. 1 is a graph of a water vapor pressure profile in a passive membrane for a reference (solid line) and steady-state (dashed line) permeation conditions;

#FIG. 2 is a graph of a reference time lag in a passive membrane;

#At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred aspects, it is to be understood that the invention as claimed is not limited to the disclosed aspects.

#Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims.

#Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. It should be appreciated that the term “enclosure” is synonymous with terms such as “packaging”, “container”, etc., and such terms may be used interchangeably as appearing in the specification and claims. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described.