Multilayer composite films and articles prepared therefrom

Abstract

The present invention is an optically transparent laminate film comprising: at least three layers of film, wherein at least two of the at least three layers comprise ionomeric films, and wherein the film can be suitable for use in a photovoltaic cell or in packaging.

Description

[0001] This application claims the priority from U.S. Application No. 60 / 634,421, filed Dec. 7, 2004.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to laminate films useful in packaging in general and as encapsulants in photovoltaic modules in particular. The invention particularly relates to transparent packaging films comprising ethylene acid copolymer ionomers. [0004] 2. Description of the Related Art [0005] Good optical properties are important in packaging materials in general and solar cell modules in particular because good performance requires that light incident to the cell be transmitted efficiently and effectively to the voltage-generating layer. Poor light transmission reduces the efficiency and / or productivity of the photovoltaic generation process. [0006] For example, a common form of solar cell module is made by interconnecting individually formed and separate solar cells made for example of crystalline silicon, and then mec...

AI Technical Summary

Benefits of technology

[0012] The present inventors have made the surprising discovery that one or more physical properties of a polymer can be significantly improved when the polymer is sandwiched as a core layer in a laminate between ionomer layers.

[0015] (2) at least one core layer unit; wherein each of the outer layers is in direct contact with opposing surfaces of at least one surface of a core layer unit, and wherein the at least one core layer unit is a single or multiple layer polymeric film or sheet that comprises at least one non-ionomeric polymer layer and wherein the optical clarity, as measured by the transmittance, and the dimensional stability of the laminate are each respectively enhanced over the expected values of said properties for the individual laminate layers.

Problems solved by technology

Poor light transmission reduces the efficiency and / or productivity of the photovoltaic generation process.

However, EVA may have certain limitations or deficiencies, such as its tendency to discolor.

Also, it can decompose and release acetic acid.

EVA used as an encapsulant material usually contains 33% (by weight) of vinyl acetate, and thus is a very soft and tacky material that makes handling EVA in a manufacturing environment somewhat troublesome.