Abstract: An information recording medium comprising a pair of disk substrates at least one of which has an optical recording layer on one surface thereof, wherein the substrates are bonded to each other by using a silicone type adhesive, directly or by the medium of a spacer, so that the recording layer may be disposed inside of the substrates. Platinum is incorporated in the above-mentioned silicone type adhesive by using a platinum type crosslinking catalyst, without using the conventional benzoyl peroxide type crosslinking catalyst. Accordingly, there is provided the information recording medium excellent in mechanical strength, reliability and durability.

Abstract: A spacer holder arrangement includes a support sheet of a self-supporting nature, at least one side of the support sheet having a low adhesive-bonding ability. A pair of concentric inner and outer spacer elements of an annular shape are disposed on the one side of the support sheet to provide a performed spacer, each of the inner and outer spacer elements having adhesive layers formed respectively on opposite sides thereof. One of the adhesive layers is interposed between each of the inner and outer spacer elements and the support sheet to bond them releasably together. The inner spacer element has a central hole therethrough which is coaxial with an aperture formed through the support sheet so that a guide rod can be passed through the aperture and the central hole.

Abstract: An optical disk comprising a pair of substrates, each having a recording surface and a reflective layer in super-position on one side, is disclosed. Such an optical disk has satisfactory shear adhesive strength and peeling strength under high temperature and high moisture conditions.

Abstract: A center hub holder tape includes a generally nonstretchable carrier tape having a series of apertures formed therethrough and spaced at an equal interval from one another along the length of the carrier tape. A series of center hubs for use in a recording disc are carried by the carrier tape, with their tubular bodies removably inserted in the apertures in the carrier tape, respectively. An adhesive layer is interposed between one side of the carrier tape and a flange around the body of the center hub to adhesively bond them together. The adhesive layer is releaseably bonded to the one side of the carrier tape so that center hub can be removed from the carrier tape together with the adhesive layer.