Package making – Methods – Forming a cover adjunct or application of a cover adjunct to...
Patent
1994-04-05
1996-03-05
Culver, Horace M.
Package making
Methods
Forming a cover adjunct or application of a cover adjunct to...
53449, 53453, B65B 502, B65B 4704, B65B 6100
Patent
active
054957052
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a package for objects that ought to be protected from moisture and gas permeation, such as pharmaceuticals, foodstuffs, cosmetics, in tablet, capsule, liquid, cream, or ointment form, and a method of manufacturing such a package.
BACKGROUND ART
A package called a Press Through Pack (PTP) is widely known as packaging for accommodating pharmaceuticals in the form of a plurality of tablets or capsules. A PTP, as will be described later in detail, is configured of a molded sheet formed of a thermoplastic synthetic resin having on one surface thereof a plurality of pocket-shaped molded portions, and a sealing sheet connected to the other surface of the molded sheet in such a manner that it closes off the openings of the pocket-shaped molded portions and protects a pharmaceutical accommodated within each of the pocket-shaped molded portions from the outer atmosphere.
A material such as a polyvinyl chloride resin, polypropylene resin, or polyethylene resin is used as the thermoplastic synthetic resin material that forms the molded sheet of this type of PTP, and aluminum foil coated with a heat-sealing agent or laminated with a heat-sealing film is typically used as the material of the sealing sheet.
In such a PTP, the water vapor and gas permeability of the molded sheet of a synthetic resin affects the stability of the object to be packaged, such as a pharmaceutical. Therefore, if a PTP is used to package an object that is readily affected by water vapor and gases, a layer of polyvinylidene chloride, which has an excellent barrier capability, is laminated over the molded sheet, in order to provide an even greater barrier effect.
Thus, a method of increasing the barrier capabilities of the molded sheet having pocket-shaped molded portions by laminating another layer over it has been proposed, but it is inevitably expensive and, in addition, unexpected problems have been cited as described below. The pocket-shaped molded portions of the molded sheet protrude out of one surface of that sheet and have a peripheral wall and a top wall, and the space therewithin opens outward into the other surface thereof, but the mold used during the molding processing stretches the material of a pocket-shaped molded portion of this type, which causes the top wall and also the peripheral edge between the top wall and the peripheral wall to thin. Since the pocket-shaped molded portions are inherently thinned locally by the molding processing, it is inevitable that there will remain some thinner portions in the top wall and peripheral edge after the molding operation, even if the barrier capabilities are increased by laminating a layer of polyvinylidene chloride thereover. Therefore, thickening the molded sheet by laminating it will not increase the barrier capability by much, but it will increase the cost and it will also increase the thickness of the molded sheet away from the pocket-shaped molded portions, where it is not necessary to have a barrier capability, while making it more difficult to push the packaged object out from within the pocket-shaped molded portions by a finger.
In addition, if the above polyvinylidene chloride layer with its high barrier capability is used as a partial laminate sheet, the inherently brittle polyvinylidene chloride will be unable to accommodate stretching of the material due to the molding processing, and fine cracks may occur. If cracking of this sort occurs, the barrier capabilities will deteriorate.
Further, although polyvinylidene chloride has excellent barrier capabilities, it is liable to discolor, so that, if the molded sheet is transparent, the discoloration can be seen from the outside in an unpleasant manner. In addition, when the molded sheet and the sealing sheet are heat-sealed together to form the package, there is a problem that bubbles are likely to occur.
It has been considered to apply the polyvinylidene chloride by coating instead of lamination, but, in this case too, problems similar to those described above occur. Further, i
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Miura Hideo
Sumimoto Mitsuhiro
Watanabe Yoshiaki
Culver Horace M.
Dai Nippon Printing Co. Ltd.
Sankyo Company Limited
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