Patented Sept. 15, 1953
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`2,652,182
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`UNITED STATES‘ PATENT OFFICE
`
`2,652,182
`COATED RUBBER STOPPER AND PROCESS
`FOR PREPARING SAME
`Robert R. Umbdenstock, Brooklyn, N. Y., assignor
`to Chas. P?zer & Co., Inc., New York, N. Y., a
`corporation of Delaware
`No Drawing. Application September 15, 1949,
`Serial No. 115,957
`2 ‘Claims. (Cl. 226-89)
`
`1
`This invention relates to a rubber stopper hav
`ing improved properties which is adapted for use
`in machines for automatically and mechanically
`stoppering vials or bottles. In particular, th1s
`invention relates to rubber stoppers having im
`proved properties and which are adapted for
`use in packaging certain drugs and therapeutic
`materials in bottles or vials under sterile con
`ditlons.
`In the past considerable difficulty has been en
`countered in the operation of automatic stopper
`ing machines using sterile, dry stoppers. After
`sterilization, the stoppers tend to adhere to each
`other in masses preventing proper feeding, jam
`ming the machines, and causing expensive de
`lays in operation. Once the stoppers have passed
`from the feed hopper into that section of the
`machine leading to the mechanism which inserts
`them into the vials or bottles, they continue to
`cause dif?culty. They do not roll or slide read
`ily over the metal guiding surfaces, but rather
`tend to adhere to them instead of moving into
`the section of the machine which positions the
`stoppers just prior to insertion. Even momen
`tary adherence to the metal surfaces causes dif
`?culty. Thus, it can be seen that any method of
`preventing such adherence of stoppers both to
`one another and to the metal surfaces of ma
`chines in which they are utilized is of great im
`portance, and constitutes a valuable contribu
`tion to the art.
`Various methods have been resorted to in
`order to overcome these difllculties. Rubber
`stoppers have been washed, sterilized and dried
`in a variety of manners but with little improve
`ment in the properties needed to provide a
`trouble-free operation in the automatic machines.
`Paraf?n has been incorporated in rubber stoppers
`during their manufacture in such a manner that
`a surface coating slowly forms. This assists in
`making the stoppers free flowing, but there is a
`marked tendency for ?akes of para?in to become
`detached from the stoppers, particularly when a
`hypodermic needle is passed through the stopper
`in a vial in order to withdraw a solution there
`from. This is particularly undesirable when the
`solution is to be used for parenteral administra
`tion.
`Lubrication of the metal surfaces of the ma
`chines over which the rubber stoppers must roll
`or slide with such materials as castor oil or
`mineral oil makes a temporary improvement in
`this operation, but it does not prevent the ad
`herence of the stoppers to one another. In ad
`dition, contact of the rubber stoppers with the
`
`2
`lubricated surfaces during continued operation
`of the machine soon removes the lubricants.
`It has now been found that an improved rubber
`stopper which is suitable for use as a bottle or vial
`closure and which is admirably adapted for use
`in automatic stoppering machines without en
`countering the above-mentioned disadvantages
`can be prepared by coating the stopper with a
`thin ?lm of a high boiling (that is, essentially
`non-volatile at normal temperature and atmos
`pheric pressure) rubber lubricant, liquid at room
`temperature, which is stable to steam at 20 lbs.
`pressure for at least 1/2 hour and which has a
`viscosity of from 50 to 500 centistokes at room
`temperature. ‘Rubber stoppers so coated. can be
`sterilized and dried in the customary manner.
`The sterile stoppers may then be fed into the
`machine used in inserting the stoppers in vials
`or bottles. The stoppers do not adhere to one
`another, they do not obstruct the mechanism
`for feeding them from the hopper into the oper
`ating section of the machine. They do not ad
`here to the metal surfaces of the machine, but
`rather slide or roll readily into position where
`they are picked up and inserted in the mouth of
`the bottle or vial. No jamming of the machines
`by the stoppers involving costly delays is en
`countered. In addition to the above advantages
`the stoppers prepared by the disclosed process
`may be inserted into bottles and vials with much
`greater ease than is the case with untreated,
`sterilized and dried stoppers. The pressure re
`quired to insert the treated stoppers is less, and
`there is less tendency for them to pop out once
`inserted. This is true no matter what machine
`or method is used for placing the stoppers in the
`mouth of the bottle or vial.
`'
`Rubber stoppers which may be used in the
`7 process of this invention consist of natural rubber
`compounded in the usual manner, reclaimed rub
`ber or synthetic rubber, e. g. neoprene. The
`treatment may be applied to, rubber stoppers of
`various sizes, operating successfully with large
`or small stoppers. The lubricants which may be
`used in this invention include the silicone oils.
`The silicone oils are mixtures of methyl poly
`siloxanes of various molecular weights and vary
`in viscosity. I prefer to use a silicone oil hav
`ing a viscosity of about 100 centistokes, but those
`of somewhat higher or lower viscosity, that is,
`from 50 to 500 centistokes are operable. In ad
`dition certain vegetable oils such as sesame or
`peanut oil which are stable to sterilization and
`Bass and Spangenberg
`possess suitable viscosity and low vapor pressure
`v.
`can be used. Certain esters, such as tributyl
`Fresenius Kabi USA, LLC
`U.S. Patent No. 8,476,010
`Exhibit 1036
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`2,652,182
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`time, the solution wasremoved from the beaker
`and the stoppers were allowed to drain. The
`coated stoppers were then placed in a covered
`metal tray in a clinical autoclave and sterilized
`for one-half hour at 20-pounds per square inch
`steam pressure. The tray‘ was then placed in a
`dryer where they were subjected to a tempera
`ture of 108° F. for four hours. Inspection of the
`stoppers showed them to be perfectly free-?owing
`‘adhering .neither .to one another nor to any
`smooth, v slanted surface. The stoppers were
`placed in the hopper of an automatic vial stopper
`ing- machine (that-of the Afotex Products Com
`pany)_ and the machine was started. ‘The stop
`pers fed faultlessly from the hopper into the
`slotted annular ring of the machine, down the
`grooved chute to the lower end where they were
`picked~up by the vacuum operated head which
`inserted them in the glass bottles. There was no
`adhesion of the stoppers in the hopper; there was
`no adhesion to the metal walls of the hopper, to
`those of the annular ring or to those of the chute.
`The stoppers fed steadilyand as rapidly as they
`were required to the point at which they were
`picked up for insertion. There was no jamming
`of. the machine and no shut-downs as had been
`encountered with - stoppers not treated by the
`process of this invention.
`This invention is not restricted to natural, re
`claimed or synthetic rubber stoppers, but maybe
`applied to any type of bottle or vial closure which
`because of its composition and the manner in
`which it must be handled in automatic stopper
`ing machines causes di?iculty due to adhesion to
`one another or to parts of the machine.
`As many apparently widely different embodi
`ments of this invention may be made without de
`parting from the spirit and scope hereof, it is to
`be understood that this invention is not limited
`to the speci?c embodiments hereof, except as de
`?ned in the appended claims.
`_
`I claim:
`1. A rubber stopper suitable for use as a closure
`for pharmaceutical containers, and particularly
`adapted for use in conjunction, with an auto
`matic stoppering' machine, which stopper is
`coated with a thin ?lm of a silicone oil having a
`viscosity of from 50 to 500 centistokes at room
`temperature and is heat-sterilized.
`2. A’ process for stoppering pharmaceutical
`containers which comprises coating ‘rubber stopl
`pers with a thin ?lm of a silicone oil, sterilizing
`the-coated stopperwith steam at elevated pres
`sure, drying the sterilized stoppers and inserting
`the same under aseptic conditions in the mouths
`of said pharmaceutical containers.
`'
`'
`'
`ROBERT R. UMBDENSTOCK. .
`
`3
`citrate and tributyl phthalate also possess suit
`able properties for use in this invention.
`In a preferred method of applying the thin ?lm
`of lubricant to the rubber stoppers for use in the
`automatic stoppering machine a silicone oil hav
`ing a viscosity of from 50 to 500 centistokesis
`dissolved in a solvent, for example chloroform
`or carbon tetrachloride, and the stoppers are
`dipped in the lubricant and are drained, dried
`10
`and sterilized. The concentration of silicone-oil
`in the solvent may vary considerably.- rlThus, a
`solution of from 0.1% to 5% of silicone oil in a
`solvent may be used. It is preferred, however,
`to use a solution containing ‘from 0.2 to 1.5% of
`silicone oil. Other lubricants in the same con
`centrations in suitable solvents. can be similarly
`employed for coating the stoppers.
`<
`-
`'
`The manner of application of the selectedlub
`ricant can be varied considerably. The stoppers
`can be dipped directly in‘ the lubricant and the
`excess removed. This method is not recom
`mended, however, since it tends to leave exces
`sive amounts of the liquidon the surface of the
`stopper. The lubricating liquid can also be ap
`plied to the stoppers by subjecting them to, a ?ne
`spray of the liquid in a device suitable for agi
`tating the stoppers so that they are coated evenly
`on all surfaces. The silicone oils may be applied
`in the form of an emulsion in water, such as
`“Silicone Emulsion 35A” (a stable emulsion of a
`silicone oil in water, manufactured by the Dow
`Corning' Corporation).
`The selectedlubricant can be applied batch
`wise as by agitation in a_ suitable vessel or it may
`35
`be applied in a continuous manner, as by passage
`of the stoppers on a continuous conveyance
`through a zone in which the lubricant is applied
`in the form of the pure liquid, a solution, or a
`spray of either of these.
`Rather than apply the silicone oils as such to
`the rubber stoppers, it is possible to form a suit
`able lubricating coating of a polymeric silicone
`on the surface of the rubber by exposing, the latter
`to a precursor for the silicones. Thus, if rubber
`stoppers, bearing a thin ?lm of water normally
`present on suchsuriaces, are exposed to the va
`pors of such a productlasrDrieFilm (a mixture of
`methylchlorosilanes manufactured by General
`Electric Corp.) for sufficient time a ?lm of" the
`silicone will be formed by reaction with water.
`Anotherjmaterial suitable for use in ‘suchrtreat
`ment is ‘dimethyl-dichlorosilane,manufactured by
`the Dow-Corning Corporation.
`_
`>
`The product of these various methods of treat
`ment is a rubber stopper which may be sterilized
`with steam in the usual manner, dried and is
`then suitable foruse in automatic bottle stopper
`ing machines of’ various types. One ,such device
`is the automatic vial stoppering machine manu
`factured by the Afotex Products Company of New
`Brunswick, New ‘Jersey.
`I
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`The following example is given by way of illus
`tration and is not intended to limit in any way
`‘ the scope or spirit of the invention. .
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`Example '
`
`vA. batch of approximately one hundred red,
`virgin rubber stoppers (standard size to ?t 20 cc.
`penicillin bottles) was, placed in, a beaker and
`covered with a 1.5% solution‘of Dow-Corning
`Corporation 100 centistokes silicone oil in chloro
`form. After agitating the stoppers for a short
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`
`References Cited in the ?le of this patent
`UNITED STATES PATENTS
`
`Number
`65,533
`I726,629
`“811,876
`2,386,466
`2,442,059
`2,470,772
`2,471,224
`2,474,704
`2,494,920
`2,573,637
`
`»
`Date
`Name
`Bishop __________ __ June 11, 1867
`Brown __'_‘__ ______ __'~_ Apr. 28,1903
`Schroeder ____’_______ Feb. '6, 1906
`Hyde '_' ___________ __\__ Oct. 9,‘ 1945
`Safford ___________ __ May 25, 1948
`Haas ____________ __ May 24,1949
`Loughborough ____ __ May 24, 1949
`rlfhayer ____ _'_ ____ __ June 28, 1949
`Warrick __________ __ Jan. 17, 1950
`Bender __________ __ Oct. 30, 1951