Plastic and nonmetallic article shaping or treating: processes – With severing – removing material from preform mechanically,... – Flash or sprue removal type
Patent
1991-07-29
1993-06-08
Woo, Jay H.
Plastic and nonmetallic article shaping or treating: processes
With severing, removing material from preform mechanically,...
Flash or sprue removal type
264241, 264250, 264255, B29C 4314, B29C 4318
Patent
active
052176681
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method for producing a rubber stopper for a vial, and more particularly to a method for producing a rubber stopper for a vessel for medicine, which is covered with a synthetic resin film.
2. Background Art
Generally, medicine in a vial is badly affected by a stopper which is used for a vessel for medicine, where a vulcanization-accelerator and other compounded ingredients contained in the rubber stopper exude in a liquid medicine in the vial, and ingredients contained in the liquid medicine are adsorbed to the rubber.
In order to prevent the rubber from affecting the liquid medicine in the vial, a rubber stopper of which surface being contacted with a liquid medicine is laminated with a synthetic resin film having a chemical resistance has conventionally been sometimes used as disclosed in Japanese Examined Patent Publication No. 9119/1979, Japanese Unexamined Patent Publication No. 47637/1982 and so on.
Several methods for producing such a covered rubber stopper have been proposed.
For instance, as disclosed in the above-mentioned Japanese Examined Patent Publication No. 9119/1979, there is a method wherein a fluorocarbon resin film is formed and cut so as to give a shape corresponding to the shape of a leg portion of a rubber stopper, a mold for forming a rubber stopper is charged with the formed film having a shape corresponding to the shape of the leg portion, moreover a rubber material is poured into the mold, and a rubber stopper is produced by forming and vulcanization.
As disclosed in Japanese Examined Patent Publication No. 53184/1982, there is a method wherein a leg portion made of a rubber which is covered with a synthetic resin film is formed and cut, then inserted into the other mold, and the top surface is integratedly formed and bonded with the upper part of the leg portion.
However, in these methods, it is necessary that firstly a formed article of a resin film having a shape corresponding to the shape of the leg portion of the rubber stopper is formed or the leg portion made of a rubber which is covered with a film is formed, then cut to pieces one by one, and moreover these pieces are inserted into a mold for forming a final product. Therefore, there is a problem that the process for producing a covered rubber stopper is complicated as a whole.
The present invention provides a method for producing these covered rubber stoppers more efficiently and economically.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, there is provided a method for producing a rubber stopper for a vial comprising:
(i) a primary forming step for obtaining a primary formed article by piling a synthetic resin film resistant to medicines or medical chemicals onto an unvulcanized rubber sheet, and pressing and heating them by means of molds comprising a first mold having a cavity being adapted to the shape of a leg portion of a rubber stopper and a second mold having a cavity being adapted to the shape of a head portion of the rubber stopper,
(ii) a secondary forming step for obtaining a secondary formed article by covering the primary formed article with a half-vulcanized rubber sheet having a hole of which diameter is the same as that of a root portion of the leg portion of the primary formed article or a little more larger than that of the root portion, and pressing and heating it by means of a pair of molds being adapted to the shape of the final product to give a secondary formed article of which under face of a head portion or portion except for the leg portion is covered with a rubber layer, and
(iii) a cutting process for cutting and removing a flash from the secondary formed article.
As a material of the synthetic resin film resistant to a medicine or a ethical drug, which is used in the method of the present invention, fluorocarbon resin, nylon, polyethylene, polypropylene and the like are given, and these materials are suitably selected in accordance with chemicals which are contained in a vial. It is necessary that th
REFERENCES:
patent: 4397903 (1983-08-01), Allen et al.
patent: 4915243 (1990-04-01), Tatsumi et al.
patent: 5078941 (1992-01-01), Tatsumi et al.
Aoki Yoshihide
Matsuzaki Masaru
Mackey James P.
Nissho Corporation
Woo Jay H.
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