Patent ID: 7820263

Claim:
A volume hologram laminate, comprising a transparent protective film formed on a front surface of a volume hologram layer via a transparent hot-melt adhesive layer having a glass transition point within the range not exceeding a heat sealing temperature of 90-180° C., wherein: (1) a half-width of diffraction light in the volume hologram layer is no greater than 30 nm; (2) a glass transition point of a resin forming the volume hologram layer is 30-70° C.; (3) the resin forming the volume hologram layer has a dynamic storage elastic modulus of 10 8 -10 10 Pa at 25° C., or a dynamic storage elastic modulus of 5×10 5 -5×10 7 Pa at 50° C., when measured at 6.28 rad/sec; and (4) said volume hologram laminate has a spotty hologram level of 3 or less according to the following conditions: the volume hologram laminate is stored for 3 days under conditions of 50° C. and 0.12 kg/cm 2 , the stored volume hologram laminate is visually examined in a triple-beam fluorescent tube at an angle where flaws appeared darkest, and a flaw level is judged from a scale of 0 with absolutely no spotty hologram flaws, and the size (mm) and density (relative value of 1-10) of the spots are multiplied to define the spotty level.