Patent ID: 8338539

Claim:
A process for preparing a transparent solar cell encapsulant film layer material, the process comprising the steps of: A. providing a blend composition comprising a zinc ionomer of a first ethylene copolymer ionomer and a zinc ionomer of a second ethylene copolymer ionomer, wherein 1) each of said first ethylene copolymer zinc ionomer and said second ethylene copolymer zinc ionomer is selected from the group consisting of zinc ionomers of copolymers consisting of copolymerized units of ethylene and from 8 wt. % to 20 wt. % of copolymerized units of a C 3 -C 8 ethylenically unsaturated carboxylic acid, based on the weight of the copolymer, and 2) said first ethylene copolymer zinc ionomer and said second ethylene copolymer zinc ionomer have comonomers of different distinct chemical identities or different weight percentages of the comonomers in the polymer chains; B. determining the secant modulus of a film obtained from said first ethylene copolymer zinc ionomer alone and a film obtained from said second ethylene copolymer zinc ionomer alone according to ASTM D882-01, wherein the film obtained from said first zinc ionomer has a secant modulus of less than 15,000 psi and the film obtained from said second zinc ionomer has an optical transmission of at least 88%; C. selecting the proportion of said first ethylene copolymer zinc ionomer and said second ethylene copolymer zinc ionomer such that they are present in said blend composition in amounts within the range of from 50 to 75 wt. % of said first ethylene copolymer zinc ionomer and from 25 to 50 wt. % of said second ethylene copolymer zinc ionomer, based on the total weight of said first and second ethylene copolymer zinc ionomers in the blend composition to form an encapsulant composition; and D. forming said encapsulant composition into a film layer wherein a) the film obtained from said encapsulant composition has a secant modulus less than 15,000 psi as measured according to ASTM D882-01, and the measured value of the secant modulus of the film is less than that predicted from a composition weighted average of the secant moduli of a film obtained from said first ethylene copolymer zinc ionomer alone and a film obtained from said second ethylene copolymer zinc ionomer alone and b) the film obtained from said encapsulant composition transmits at least 88% of incident visible light and has a haze value of equal to or less than 3% as determined according to ASTM D1003-00.