Patent ID: 7857931

Claim:
A method for preparing a plastic substrate having a multi-layer structure comprising the steps of: a) forming a first organic-inorganic hybrid buffer layer on one side of a plastic film by coating a buffer composition in a sol state thereon and curing the buffer composition, wherein the plastic film having a thickness of 10 to 1,000 microns (μm) is made of at least one selected from the group consisting of a homopolymer, at least one polymer blend, and a polymer composite material including organic or inorganic additives; b) forming a gas barrier layer on the first organic-inorganic hybrid layer by coating an inorganic material thereon, wherein the gas barrier layer having a thickness of 5˜1000 nm is made of at least one inorganic material selected from the group consisting of SiO x (where x is an integer of 1-4), SiO x N y (where each of x and y is an integer of 1-3), Al 2 O 3 , and ITO; c) forming a second organic-inorganic hybrid buffer layer on the gas barrier layer by coating the buffer composition of the step a) and curing the buffer composition to prepare a multi-layer film; d) preparing another multi-layer film having the same structure as that obtained in the step c); and e) attaching the plastic film of the step c) and the step d), so that sides with no multi-layer film contact each other, and then each layer forms a symmetrical arrangement centering around the plastic films, wherein each of the first organic-inorganic hybrid buffer layer and the second organic-inorganic hybrid buffer layer having a thickness of 0.5˜20 micron(μm) is prepared from partial hydrolysis of a buffer composition comprising 20-99.99 wt % of at least one organic silane selected from the group consisting of the compounds represented by Chemical Formula 1 below and 0.01-80 wt % of at least one metal alkoxide selected from the group consisting of the compounds represented by Chemical Formula 2: (R 1 ) m —Si—X (4−m) (1) where X, which may be identical or different, is hydrogen, halogen, C 1-12 alkoxy, acyloxy, alkylcarbonyl, alkoxycarbonyl, or —N(R 2 ) 2 (where R 2 is H or C 1-12 alkyl); R 1 , which may be identical or different, is C 1-12 alkyl, alkenyl, alkynyl, aryl, arylalkyl, alkylaryl, arylalkenyl, alkenylaryl, arylalkynyl, alkynylaryl, halogen, substituted amino, amide, aldehyde, keto, alkylcarbonyl, carboxy, mercapto, cyano, hydroxy, C 1-12 alkoxy, C 1-12 alkoxycarbonyl, sulfonate, phosphate, acryloxy, methacryloxy, epoxy, or vinyl; oxygen or —NR 2 (where R 2 is H or C 1-12 alkyl) may be inserted between R 1 and Si to give —(R 1 ) m —O—Si—X (4−m ) or (R 1 ) m —NR 2 —Si—X (4−m ); and m is an integer of 1-3; and M-(R 3 ) z (2) where M is a metal selected from the group consisting of aluminum, zirconium, and titanium: R 3 , which may be identical or different, is halogen, C 1-12 alkyl, alkoxy, acyloxy, or hydroxy; and Z is an integer of 3 or 4.