| 摘要 |
PROBLEM TO BE SOLVED: To enable uniform compensation of phase difference and to improve productivity by heating a film by a vacuum heating method to volatilize a plasticizer in at least either a preheating zone or a stretching zone in a stretching process. SOLUTION: For example, a film injected from a die 4 is cooled in the nip part between a rubber roll 5 and a metal roll 6 at 140 deg.C surface temp. The stretching process includes a vacuum heating room 1 as a preheating zone and a roll stretching machine 2 as a stretching zone. The film before stretched is passed through the vacuum preheating room 1 at 1 Pa vacuum degree and 100 deg.C room temp. for 10 min, then uniaxially stretched in the longitudinal direction by the roll stretching machine 2 at 175 deg.C stretching temp. with 1.4 time magnification of stretching, and then passed through a cooling and annealing zone 3 to obtain a film having 68μm average thickness. Although the production equipment is inexpensive, the obtd. phase difference plate shows uniform phase difference and excellent productivity. By the vacuum heating method, the plasticizer can be volatilized at lower temp. to suppress diffusion of the plasticizer in the film.
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