Patent ID: 8268227

Claim:
A method for forming optical compensating films, comprising: (a) providing a suspension containing clay, wherein the particle size of the clay is a diameter of about 1-100 nm and a thickness of about 0.1-10 nm; (b) adding a mono-functional acrylic oligomer of formula (I) in the suspension, wherein n 1 is 2-25, R 1 is C 1-10 alkyl or H and R 2 is H or CH 3 ; (c) adding a water-soluble polymer in the suspension; (d) adding a bi-functional acrylic oligomer of formula (II) in the suspension, wherein, n 2 is 3-50, R 3 and R 4 independently are H or CH 3 ; (e) after the step (d), drying the suspension to form a film; (f) exposing the film under UV light to cure the film, wherein the UV light exposing condition comprises using UV light of 200-450 nm, single exposure of UV light energy of 1-10 J/cm 2 , exposing rate of 1-2 m/min, and exposing two sides of the film under UV light for 1-3 times; and (g) stretching the film, wherein the film has only a negative C-plate property before the stretching and has both negative C-plate and positive A-plate properties after the stretching.