A vial for housing hygroscopic materials such as tableted chemicals
contains a desiccant canister secured to the inside at its base.
The desiccant canister is punctured immediataly prior to use. The
vial containing hygroscopic materials is sealed with a lid that
resists the entrance of water vapor into the vial.
What is claimed is:
1. A method of protecting hygroscopic materials, comprising:
a) filling a package with desiccant;
b) sealing the package to prevent the entrance of moisture into
c) placing the sealed package in the base of a container;
d) puncturing the desiccant package immediately prior to placing
the hygroscopic material in the container;
e) placing the hygroscopic material in the container;
f) placing a lid over the container such that the container is
substantially sealed against moisture.
2. The method of claim 1 further comprising after step e) attaching
a moisture or tamper resistant seal to the lip of the container.
3. The package of claim 1 further comprising a moisture-proof tamper-evident
seal attached to the open end of the container, the seal providing
increased protection against moisture entering the package or evidence
of tampering if the seal is broken.
4. The package of claim 1 containing hygroscopic materials in the
form of tablets.
BACKGROUND OF THE INVENTION
Desiccants are widely used in connection with hygroscopic chemicals
to prevent or retard the problem of degradation of these chemicals.
Typically the problem is solved by building very expensive humidity
controlled rooms in which tablets or powders are packaged into vials
which are then sealed against moisture. The problem may also be
solved by providing a desiccant canister which is permanently open
to expose it to the surrounding air in a vial containing tablets.
The canister itself must be protected from moisture until it is
placed in the vial either at a packaging facility or at the pharmacy.
The desiccant could also be incorporated into the closure (lid)
such as is done in the U.S. with certain chemicals. This method
is widely used in Europe for effervescent products using friction-type
closures. In either case, the desiccant can become separated from
the product, exposing the product to moisture. The desiccant itself,
prior to use, must be carefully packaged to avoid moisture exposure
that would diminish its effectiveness.
DE 3622773 discloses a plastic stopper closure with a dryer insert
that may be pressed into the opening of a container such as a tube
or bottle. This stopper seals to the inner surface of the container
and is filled with a drying agent which is held in place by a disk.
DD 148749 discloses a plastic closure for medication bottles consisting
of a hollow elastic stopper containing an elastic telescoping insert
filled with stabilizer.
SUMMARY OF THE INVENTION
The present invention solves the problem of protecting hygroscopic
chemicals by providing a desiccant canister which is filled with
fresh desiccant and immediately sealed against moisture. The sealed
canister is placed in the base of the tablet container. Immediately
before the tablets are placed in the container the desiccant canister
is punctured to expose the desiccant to the air in the container.
Tablets are then placed in the container and the container is sealed
against the ambient air. This method provides excellent protection
for hygroscopic chemicals. At the same time it avoids the necessity
of expensive humidity control in the packaging facility, and the
necessity of protecting a porous desiccant canister until it is
placed in use and sealed. This method has the added advantage over
containers having desiccant canisters in the lid, that an additional
moisture seal or tamper evident seal may be placed over the lip
of the container before the lid is put in place.
The containers of this invention are useful for containing hygroscopic
materials such as agricultural or medicinal compositions, ensuring
both moisture resistance and tamper evidence to the contents of
This invention pertains to a container or package containing sealed
This invention also pertains to a container or package in which
a desiccant (drying agent) canister is attached to the inside in
such a way that any water in the product or water vapor in the container
can diffuse into the desiccant. This invention also pertains to
a process for making this container or package.
The container can be any shape or size such as a jar, vial, bottle,
tube, etc. The material of construction can be anything that is
relatively impermeable to water vapor such as glass, plastic, metal,
foil-lined paperboard, etc.
The drying agent can be anything that is approved for use with
the product. Adsorbants such as montmorillonite clay, silica gel,
molecular sieves, CaO, CaSO.sub.4 CaCl.sub.2 can all be used.
The desiccant is secured to the inside of the container in such
a way that it stays with the container when the product is removed.
The desiccant could be put in a cylindrical container or canister
and pressed or glued into the bottom of the container. It could
be a doughnut-shaped piece or it could be made an integral part
of the container.
The value of the invention is increased by protecting the desiccant
from ambient air until just before the product is put into the container.
The drying agent can be sealed with a metal foil or plastic lid
which can be punctured just before use to expose the desiccant.
The contents need to be protected from humid air leaking into the
container. A moisture-proof lid (closure) could be heat sealed to
the top of the container. Another way would be to use a closure
that was essentially air tight. This could be done by using several
threads, fine threads, soft closure liner, external seal, etc.
This invention pertains to a package comprised of the following:
1. a vial;
2. a covered or packaged desiccant attached to the inside of the
3. an optional moisture-resistant and tamper-resistant seal attached
to the lip of the vial to protect the contents; and
4. a lid closing the vial.
DESCRIPTION OF FIGURES
FIG. 1 is a side view of the container.
FIG. 2 is a plain view of the desiccant canister showing holes
after being punctured.
DETAILED DESCRIPTION OF THE INVENTION
This invention puts a drying agent (desiccant) in a container so
that: the desiccant will not fall out; the container can have a
moisture-proof tamper-evident seal; and the desiccant is exposed
to the air only just before use.
As shown in FIG. 1 the container may be a cylindrical vial (1)
having a closed end (bottom) (2) and an open end (top) (3). The
container may be of glass, metal, plastic, foil-lined paperboard
or any material suitable for the purpose. A desiccant canister (4)
is secured to the inside of the cylinder (1). The desiccant canister
may be of any material that forms a barrier to water vapor. The
entire canister may be foil or polymer material, or may be a rigid
material with a foil or polymer film seal. The desiccant canister
(4) contains a desiccant (drying agent) material (5), usually in
the form of beads or granules. Desiccant materials are well known
in the art. Among the typical desiccants are montmorillonite clay,
silica gel, molecular sieve, CaO, CaSO.sub.4 and CaCl.sub.2. The
choice of desiccant material is not critical to this invention.
The amount of desiccant is determined by the needs of the user.
The desiccant canister (4) of this invention is closed with a seal
(6) immediately after the desiccant (5) is placed in it. The seal
(6) prevents the entrance of water vapor before the desiccant (5)
is intended to be used. The seal (6) may be of any material that
will prevent the passage of water vapor across it. Polymer films
and metal foils are commonly used. The canister (4) remains sealed
until immediately prior to placing contents in the container (1).
The contents may be tablets or other material which must be dried
or kept dry. Such materials are usually pressed dried chemicals
or mixtures. They may be pharmaceutical or over-the-counter drugs
in tablet form. They may also be herbicides or pesticides.
Immediately prior to placing the tablets in the container (1) the
seal (6) on the canister (4) is punctured (perforated) to expose
the desiccant (5) (FIG. 2). The only requirement is that the holes
(7) made by the puncture are large enough to allow water vapor to
pass through, but smaller than the desiccant granules.
"Immediately prior" means specifically that under the
conditions of humidity in the packaging facility during packaging
the performance of the desiccant capacity will not be substantially
reduced between the time the canister is punctured and the time
the container is filled and sealed.
The container is closed with a lid (8) immediately after the contents
are placed into it. The lid (8) can be any lid which provides a
reliable closure. The lid (8) may be a friction fit or it may be
threaded to match threads on the container. An optional seal (9)
may be placed over the open end (3) of the container (1) to provide
additional protection against water vapor entering the container
(1). The seal (9) also may provide evidence of tampering with the
contents. A broken seal (9) evidences that the container (1) has
been opened and (3) may give evidence that contents have been removed
or that the contents may be unreliable at the point of purchase.
The seal (9) may be any water barrier material such as polymer film
or a metal foil. The seal (9) can be heat sealed to the open end
(3) of the container (1) before the lid (8) is put on. The seal
(9) can also be put on with the lid (8) and induction sealed to
the open end (3) of the container (1) later. The seal (6) and the
seal (9) are understood to have the ability to prevent water vapor
from passing across them. Therefore, they may be made of a foil
or a film or a combination of materials known to one skilled in
the art for the purpose of forming a barrier against water vapor.
The configuration and size of the container, the placement of the
desiccant canister, the amount of desiccant, the size of the holes
in the desiccant seal, and other factors may change with the contents
to be housed without departing from this invention.
The preferred embodiment is a vial for housing effervescent herbicide
A cylindrical vial (1) is illustrated in FIG. 1. It is 65 mm high
and has an inside diameter of 45 mm. Such vials are slightly larger
at the top (3) than at the bottom (2). Polypropylene is preferred
for making the vial.
A standard 43 mm polypropylene cap is used as a desiccant canister
(4). The canister (4) is filled with 7 grams of molecular sieves
(5). The sieves are type 4A and are 8-12 mesh (1.7-2.4 mm) beads.
The lip of the canister is sealed with a foil/polymer film. The
seal (6) is made by heat and the outer edges of the film are sealed
to the top circumference of the canister (4).
The sealed desiccant canister (4) is pressed into the bottom (2)
of the vial (1). Because of the tightness of the fit the desiccant
cannot be removed unless the vial (1) is broken.
Just before the vial (1) is filled with effervescent tablets the
foil seal (6) is punctured. The tool used makes 17 holes (7) that
are 1.0 mm in diameter. The holes (7) are small enough to prevent
the desiccant (5) from falling out, but provided enough area to
allow water vapor from the product housed in the vial or from the
space inside the vial to diffuse into the desiccant (5). The advantage
of preparing a sealed, packaged desiccant (5) is that moisture levels
in the ambient air are not a concern during vial (1) storage or
at any time before the desiccant canister (4) is punctured. Commonly
available desiccant canisters have openings and must be carefully
stored in dry conditions so that their value isn't lost before the
desiccant is used.
The effervescent tablets are put into the vial (1) immediately
after the desiccant canister (4) is punctured and the lid (8) is
immediately attached. The lid (8) assembly includes a polymer/foil/polymer
piece that is 0.38 mm thick. The lid (8) is screwed on tightly and
the seal (9) is sealed by induction heating. The seal (9) is moisture-proof
and provides tamper evidence.
The present invention provides the advantages of a canister containing
that fresh desiccant has been stored without the need for special
dehumidification of the packaging facility or storage room; the
desiccant is not separatable from the container; and in the case
of effervescent tablets, the desiccant dries the tablets during
storage, prolonging the shelf life of the tablets.
The first step is to fill the desiccant canister (4) with the desiccant
(5). The amount of desiccant to be used will depend on the diameter
and depth of the canister. The desiccant should almost fill the
cavity, but not be above the edge of the canister. The desiccant
can be weighed out or measured by volume with a measuring spoon
or cup. The desiccant used must be greater in diameter than the
holes that will be punched in the canister lid later.
The desiccant will be exposed to ambient relative humidity during
this step. If the relative humidity is less than 30-40% there is
little concern with speed in assembly. If the relative humidity
is greater than 40% the time that the desiccant is exposed will
have been kept down to just a few minutes so that the desiccant's
capacity is not reduced by picking up water from the air.
The canister is tapped lightly to make sure the desiccant is level.
The seal is placed on top of the canister. This is easiest to do
if the seal is formed with a lip on it so that it will be automatically
centered on the canister. The seal is made preferably with a conduction
heat sealer. The time and temperature will depend upon the polymer
that is used on the seal. In the preferred embodiment the heat sealer
was held in direct contact with the seal for 2-3 seconds at a temperature
of 220.degree. C.
The canister is placed into the top of the vial (1). It is gently
pushed down by hand until resistance is met. Care must be taken
to be sure the desiccant canister is kept level. The canister is
then pushed to the bottom of the vial with a cylindrical tool. The
tool can be made of any relatively hard material such as wood, plastic,
or metal. The tool can be mounted in a leveraged device such as
a drill press.
The vial/desiccant combination can be stored for a long period
of time (years). It need not be stored in any particular environment.
Immediately prior to placing the tablets in the container the desiccant
canister seal is punctured with a tool that has needle-like protrusions.
When possible this step should be done within a few minutes of filling
the vial. Again the time will depend on the relative humidity and
the desiccant type. If the room had a relative humidity of only
15% the canister seal could be pierced 24 hours before the vial
is filled. If the relative humidity were 60% it would be best if
the seal were punctured no more than 5 minutes before adding the
tablets. The tool can have from 1 to 100 spikes, with 15-25 being
preferred. The diameter of the spikes has to be smaller than the
size of the desiccant used, with 1 mm being preferred. The outside
diameter of the tool should be smaller than the inside diameter
of the vial. A drill press type machine (as described above for
inserting the canister into the vial) can be used to put the holes
in the top of the desiccant canister.
The tablets are counted out and placed into the vial one on top
of another. The top tablet must be below the top of the vial. A
circular foam spacer can be inserted if the empty space is so large
that the tablets will move around when the cap is put on.
The vial closure (cap) preferably has the tamper-evident, moisture
resistant seal (9) inside. The cap is screwed on to the vial as
tightly as possible.
The most convenient way to seal (9) to the vial is by induction
sealing. This kind of sealer uses radio frequency energy to melt
the polymer on the seal. The frequency used and the time it is on
will depend on the polymer used. In the preferred embodiment 275
kHz and 300 watts were used. The load cell is placed on top of the
assembled vial for 2 seconds. The vial is allowed to cool at room
temperature for 5 minutes before handling it further.
Effervescent tablets packaged by the method of the preferred embodiment
and stored in the sealed container showed no degradation after one
From the foregoing description, one skilled in the art can easily
ascertain characteristics of this invention, and without departing
from the spirit and scope thereof, can make various modifications
of the invention to adapt it to various uses and conditions.