Hermetically sealed container for large-sized precision sheet (semi-) product
A relatively light resinous hermetically sealed container for a large-sized precision sheet (semi-)product, such as a photomask, is provided so as to accommodate, support and transport the precision sheet (semi-)product safely and in an airtight manner. The hermetically sealed container includes a main body and a lid member respectively having peripheral flange portions abutted to each other so as to accommodate a precision sheet (semi-)product therein. Each of the main body and the lid member is formed as a vacuum or air-pressure formed thermoplastic resin sheet equipped with a reinforcing rib.
1 . A hermetically sealed container for a large-sized precision sheet (semi-)product, comprising a main body and a lid member respectively having peripheral flange portions abutted to each other so as to accommodate a precision sheet (semi-)product therein, wherein each of the main body and the lid member comprises a vacuum or air-pressure formed thermoplastic resin sheet equipped with a reinforcing rib.
2 . A container according to claim 1 , wherein each of the thermoplastic resin sheets forming the main body and the lid member comprises an antistatic resin.
3 . A container according to claim 1 , wherein at least one of the peripheral flange portions of the main body and the lid member is provided with a groove for receiving an O-ring for hermetic sealing.
4 . A container according to claim 1 , wherein a plurality of holding members for holding the precision sheet (semi-)product are disposed at plural positions adjacent to the peripheral flange portions of the main body and the lid member, respectively.
5 . A container according to claim 4 , wherein each holding member on one of the main body and the lid member comprises a tapered portion and an abutting side wall having a height smaller than the thickness of the precision sheet (semi-) product, and each holding member on the other of the main body and the lid member has a tapered portion longer than the tapered portion of the holding member on said one of the main body and the lid member.
6 . A container according to claim 4 , wherein the holding members are integrally captured with the vacuum or air-pressure formed thermoplastic resin sheet and held therewith.
7 . A container according to claim 6 , wherein the holding members comprise a thermoplastic resin which is softer and richer in slidability than the thermoplastic resin sheet.
8 . A container according to claim 4 , wherein the vacuum or air-pressure formed thermoplastic resin sheet is provided with aprons adjacent to the holding members for providing a reinforced strength for supporting the weight of the precision sheet (semi-)product.