Development of a new evaluation method for gelatin film sheets

Gelatin film sheets are often used to form the shell in soft capsules prepared using the rotary die method. Examination of the film sheet properties is extremely important when materials other than gelatin are used. We examined the relationship between the width and the tensile strength of the gelatin film sheet in order to establish the required indexes of the gelatin film sheets. The coefficients of correlation (R) of the linear regressions 4 and 15 min after preparation of the gelatin film sheets were 0.9858 and 0.9167, respectively. These results suggest that the tensile strength decreased when the width of the gelatin film sheet increased. Subsequently, we examined the relationship between time and the tensile strength. We observed new phenomenon: the tensile strength of the gelatin sheets increased with time, following two phases. The first phase corresponded to over phase transition point at 4, 8, and 15 min and the second phase corresponded to under transition point at 15, 30, and 60 min. The R values were 0.9952 (4, 8, 15 min) and 0.9494 (15, 30, 60 min).